JP2016057567A - Optical module, optical transmission/reception module, and flexible substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module, optical transmission/reception module and flexible substrate capable of suppressing the occurrence of disconnection.SOLUTION: In a surface of an end part of a flexible substrate 11 of an optical module, in order from a left side to a right side, a grounding surface terminal 41L, a pair of signal surface terminals 42A and 42B, a grounding surface terminal 41S and a pair of signal surface terminals 42A and 42B, and a grounding surface terminal 41L are arranged side by side. Both ends of a plurality of surface terminals lined in a lateral direction are the grounding surface terminals 41L. A plurality of surface terminals extend from a bottom end of the flexible substrate 11, and the grounding surface terminals 41L located at opposite ends are equal in a length along a lengthwise direction. The signal surface terminals 42A and 42B, and the grounding surface terminal 41S all are equal in a length, and a length of the grounding surface terminal 41L located at opposite ends is configured to be longer than a length of other surface terminals.SELECTED DRAWING: Figure 3A

Description

  The present invention relates to an optical module, an optical transceiver module, and a flexible substrate.

  The optical module includes optical high frequency components. A high-frequency electrical signal is input to and / or output from the optical high-frequency component. Therefore, an electrical signal input to the optical high frequency component and an electrical signal output from the optical high frequency component propagate through the transmission line. Then, two substrates are overlapped and connected at the connection point between the transmission line and the transmission line, or at the connection point between the optical high-frequency component and the transmission line. The two substrates are referred to as an upper substrate and a lower substrate. For example, consider a case where an optical high-frequency component and a wiring board are connected. A wiring substrate such as a flexible substrate is the upper substrate, and a ceramic substrate provided in the optical high-frequency component is the lower substrate.

  A microstrip line is formed on the upper substrate in order to propagate a high-frequency electric signal. The upper substrate is further formed with a terminal portion (hereinafter referred to as an upper substrate end portion) connected to one end portion of the microstrip line. Here, the microstrip line is a transmission line for propagating a high-frequency electric signal, a ground conductor layer that is a ground potential is formed on the back side of the substrate, and a linear signal wiring pattern is formed on the front side of the substrate. Is done. A terminal portion (hereinafter referred to as a lower substrate terminal portion) is formed at an end portion of the lower substrate provided in the optical high frequency component. Both the upper substrate terminal portion and the lower substrate terminal portion include a ground terminal and a signal terminal. The upper substrate terminal portion and the lower substrate terminal portion are connected in physical contact (overlapping) via a conductive bonding material such as solder. Patent Document 1 discloses an optical module that uses a resonance frequency component of a substrate that transmits a high frequency as a use band due to the structure of the flexible printed circuit board.

JP 2009-94390 A

  7A and 7B are a plan view and a bottom view, respectively, of an end portion of an upper substrate 111 (for example, a wiring substrate) according to the related art. 7A shows the surface (upper surface) of the upper substrate 111, and FIG. 7B shows the back surface (lower surface) of the upper substrate 111, respectively. FIG. 8 is a plan view of an end portion of a lower substrate 112 (for example, a ceramic substrate of an optical high-frequency component) according to the prior art, and shows a surface (upper surface) of the lower substrate 112. Here, as an example, a case where two pairs of differential transmission lines 120 are formed on the upper substrate 111 is shown. One differential transmission line includes a pair of signal wirings 121A and 121B formed on the front surface side of the upper substrate 111 and a ground conductor layer 122 formed on the back surface side of the substrate.

  An upper substrate terminal portion 131 is formed at the end of the upper substrate 111. The upper substrate terminal portion 131 includes a plurality of grounding terminals and a plurality of signal terminals. Each terminal includes a front surface terminal formed on the front surface side of the upper substrate 111 and a back surface terminal formed on the rear surface side of the upper substrate 111, and forms a pair. The pair of front surface terminals and back surface terminals overlap in plan view and are electrically connected via via holes 123 (via holes). As shown in FIG. 7A, a ground surface terminal 141 and a pair of signal surface terminals 142A and 142B are repeatedly arranged on the surface of the end portion of the upper substrate 111 in order from the left side of the drawing. Both ends of the surface terminal are ground surface terminals 141. As shown in FIG. 7B, on the back surface of the end portion of the upper substrate 111, a grounding back surface terminal 151 and a pair of signal back surface terminals 152B, 152A are repeatedly arranged in order from the left side of the drawing. Both ends of the group of back terminals are ground back terminals 151.

  A lower substrate terminal portion 132 is formed at an end portion of the lower substrate 112. The lower substrate terminal portion 132 includes a plurality of ground terminals and a plurality of signal terminals. Each terminal includes a surface terminal formed on the surface side of the lower substrate 112. As shown in FIG. 8, a ground surface terminal 161 and a pair of signal surface terminals 162A and 162B are repeatedly arranged in order from the left side of the figure on the surface of the end portion of the lower substrate 112. Both ends of the group of surface terminals are ground surface terminals 161.

  As described above, the upper substrate terminal portion 131 of the upper substrate 111 and the lower substrate terminal portion 132 of the lower substrate 112 are physically connected via solder. Here, a connection region in which the upper substrate back surface terminal of the upper substrate terminal portion 131 overlaps with the lower substrate surface terminal of the lower substrate terminal portion 132 through solder is shown by hatching in FIG. 7B. The signal wiring 121A (121B) and the signal surface terminal 142A (142B) are formed of a continuous metal foil, and a transition region 124 in which the wiring width changes is provided between them. Note that cover lays 125 are formed on both surfaces (front surface and back surface) of the upper substrate 111, respectively.

  Due to requests for integration of optical high-frequency components, the number of transmission lines formed on the upper substrate may increase. Along with this, the width of the upper substrate 111 increases. The inventors have found that when the width of the upper substrate 111 is increased and the upper substrate 111 is hardened, disconnection occurs more frequently at the connection portion between the upper substrate 111 and the lower substrate 112. There has been a problem that the failure occurrence rate of the optical module is increased due to occurrence of disconnection at a high frequency. The inventors examined the cause of the disconnection. As a result, when an external force is applied to the upper substrate 111, the bending applied to the upper substrate 111 near the upper end of the connection region diagram (cross section shown as B in FIG. 7A) in plan view with respect to the bending of the upper substrate. Stress is concentrated. As a result, the inventors have found that disconnections frequently occur in the vicinity of the transition region 124 located between the signal wiring 121A (121B) and the signal surface terminal 142A (142B). The upper end of the connection region of each upper substrate back surface terminal coincides in the vertical direction of the figure (the position where the arrow B penetrates), and even when multiple external forces are applied to the upper substrate 111, it is near the upper end of the connection region. The bending stress related to the upper substrate 111 is concentrated.

  The present invention has been made in view of such a problem, and an object thereof is to provide an optical module, an optical transceiver module, and a flexible substrate in which occurrence of disconnection is suppressed.

  (1) In order to solve the above problems, an optical module according to the present invention is electrically connected to one or a plurality of transmission lines and the one or a plurality of transmission lines, and is first in plan view. A plurality of upper substrate back surface terminals arranged in the direction and formed on the back surface side, and a plurality of lower substrate surfaces formed on the front surface side that are connected to and overlap each of the plurality of upper back surface terminals. A plurality of upper substrate rear surface terminals that are adjacent to each other and have a second direction intersecting the first direction from the lower substrate side. The first back surface terminal and the second back surface terminal that extend together toward the transmission line side, the first back surface terminal has a first connection region that is a region overlapping with the corresponding lower substrate surface terminal, The second back terminal is A second connection region which is a region overlapping with a lower substrate surface terminal, and a position of a second tip on the transmission line side of the second connection region is on the transmission line side of the first connection region It is characterized by being on the transmission line side along the second direction from the position of the first tip.

  (2) In the optical module according to (1), the upper substrate is formed on the front surface side so as to overlap with at least a part of the first back surface terminal in plan view, and the first back surface. A first surface terminal electrically connected to the terminal and a first signal wiring of the transmission line formed on the surface side and electrically connected to the first surface terminal may be further included.

  (3) In the optical module according to (2), the width of the first signal wiring may be narrower than the width of the first surface terminal.

  (4) In the optical module according to any one of (1) to (3), the upper substrate is formed on the surface so as to exclude at least the first connection region in plan view. The protective layer further includes the protective layer further than the second tip of the second connection region along the second direction in plan view with respect to the first tip of the first connection region. It may extend to the lower substrate side.

  (5) The optical module according to any one of (1) to (4), wherein the second back surface terminal is one of the plurality of upper substrate back surface terminals arranged in the first direction. The plurality of upper substrate back surface terminals are arranged at ends, and include a third back surface terminal and a fourth back surface terminal that extend in the second direction from the lower substrate side to the transmission line side, and A back terminal is disposed at an end on the other side of the plurality of upper substrate back terminals, and the third back terminal is a region overlapping with the corresponding lower substrate surface terminal. A fourth tip having a connection region, wherein the fourth back surface terminal has a fourth connection region that overlaps the corresponding lower substrate surface terminal, and is located on the transmission line side of the fourth connection region. The position of the third tip is located on the transmission line side of the third connection region. More may be in the transmission line side along the second direction.

  (6) In the optical module according to any one of (1) to (5), the upper substrate is formed on the front surface side so as to overlap with at least a part of the second back surface terminal in plan view. And a second surface terminal that is electrically connected.

  (7) In the optical module according to (6), the upper substrate has a back surface from a surface of the upper substrate to a region where the second back surface terminal and the second surface terminal overlap in plan view. It may further include a via hole penetrating through.

  (8) The optical module according to any one of (1) to (7), wherein the upper substrate further includes a ground conductor layer of the transmission line formed on a back surface side, and the second back surface The terminal may be electrically connected to the ground conductor layer.

  (9) In the optical module according to any one of (1) to (7), the upper substrate further includes a DC voltage wiring, and the second back terminal is electrically connected to the DC voltage wiring. May be connected.

  (10) An optical transceiver module according to the present invention is an optical transceiver module comprising the optical module according to any one of (1) to (9) above and another optical module, wherein the optical module and the optical module One of the other optical modules may be an optical transmitter, and the other may be an optical receiver.

  (11) The flexible substrate according to the present invention is electrically connected to one or a plurality of transmission lines and the one or a plurality of transmission lines, arranged in a first direction in plan view, and formed on the back surface side A plurality of upper substrate back surface terminals, wherein the plurality of upper substrate back surface terminals are connected to overlap each of a plurality of lower substrate surface terminals formed on the surface side of another substrate. The plurality of upper substrate back surface terminals are adjacent to each other and extend in a second direction intersecting the first direction from the other substrate side to the transmission line side, The first back surface terminal includes a first connection region that overlaps the corresponding lower substrate surface terminal, and the second back surface terminal corresponds to the corresponding lower substrate surface terminal. Is a region that overlaps The second connection region has a second connection region, and the second connection region has a second tip position that is closer to the transmission line than the first connection point in the first connection region. Along the transmission line side.

  The present invention provides an optical module, an optical transceiver module, and a flexible substrate in which occurrence of disconnection is suppressed.

1 is a plan view of an optical transceiver module according to a first embodiment of the present invention. It is a schematic diagram which shows the connection of the flexible substrate and ceramic substrate which concern on the 1st Embodiment of this invention. It is a top view of the flexible substrate end concerning a 1st embodiment of the present invention. It is a bottom view of the flexible substrate end part concerning a 1st embodiment of the present invention. It is a top view of the ceramic substrate end part concerning a 1st embodiment of the present invention. It is a top view of the flexible substrate edge part concerning a 2nd embodiment of the present invention. It is a bottom view of the flexible substrate end part concerning a 2nd embodiment of the present invention. It is a top view of the ceramic substrate edge part which concerns on the 2nd Embodiment of this invention. It is a top view of the upper-side board | substrate edge part which concerns on a prior art. It is a bottom view of the upper-side board | substrate edge part which concerns on a prior art. It is a top view of the lower board | substrate edge part which concerns on a prior art.

  Hereinafter, embodiments of the present invention will be described specifically and in detail based on the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof will be omitted. In addition, the figure shown below demonstrates the Example of embodiment to the last, Comprising: The magnitude | size of a figure and the reduced scale as described in a present Example do not necessarily correspond.

[First Embodiment]
FIG. 1 is a plan view of an optical transceiver module 100 according to the first embodiment of the present invention. FIG. 1 schematically shows components housed in the housing of the optical transceiver module 100. Specifically, a state in which the upper plate of the housing 1 (a plate-like member on the side where the optical receiving component 3, the optical transmitting component 4 and the like are mounted with respect to the printed circuit board 2) is removed is shown. The optical transmission / reception module 100 of this embodiment has an external dimension conforming to the CFP2 standard, but is an optical module conforming to another standard or an optical transceiver module of a unique size not conforming to the standard. Also good.

  As shown in FIG. 1, a flat printed board 2 is fixed inside the housing 1, and on the printed board 2, an optical receiving component 3 (ROSA) that is a main optical component, and an optical transmitting component 4. (TOSA) are mounted, and these optical components are fixed on the printed circuit board 2 by a component tray 5. The optical receiving component 3 and the optical transmitting component 4 are examples of optical high frequency components.

  An optical signal input from the optical receiving side of the optical receptacle 6 of the optical transceiver module 100 passes through the optical fiber 92, passes through the optical fiber tray 7 that holds the optical fiber 92, and is electrically supplied by the optical receiving component 3. Converted to a signal. A flexible substrate 11 (FPC: Flexible Printed Circuit) is connected to the optical receiving component 3, and a high-frequency electric signal output from the optical receiving component 3 propagates through a transmission line on the flexible substrate 11. The optical receiving component 3 includes a ceramic substrate 12 (not shown). An upper substrate terminal portion 31 (not shown) is formed at the end of the flexible substrate 11 (upper substrate), and a lower substrate terminal portion 32 (at the end of the ceramic substrate 12 (lower substrate)). (Not shown) is formed, and the upper substrate terminal portion 31 and the lower substrate terminal portion 32 are connected via solder. The electric signal output from the optical receiving component 3 is amplified by the electric high frequency component 8 (amplifier) through the flexible substrate 11 and output to the device connected to the card edge connector 9. In the optical transceiver module 100, from the optical receiving portion of the optical receptacle 6 to which an optical signal is input to the optical receiving portion of the card edge connector 9 that includes the optical receiving component 3 and outputs an electrical signal. Is an area (function) corresponding to the optical receiving module.

  In addition, an electrical signal input from a device connected to the card edge connector 9 of the optical transceiver module 100 is amplified by an electrical high-frequency component 10 (amplifier), converted into an optical signal by the optical transmission component 4 via the flexible substrate 91. Is done. The optical signal converted by the optical transmission component 4 is output from the optical receptacle 6 via the optical fiber 92 and the multiplexer. In the optical transceiver module 100, from the optical transmission part of the card edge connector 9 to which an electrical signal is input to the optical transmission part of the optical receptacle 6 that includes the optical transmission component 4 and that outputs the optical signal. Is an area (function) corresponding to the optical transmission module.

  The main feature of the present invention is the configuration of the upper substrate terminal portion 31 of the flexible substrate 11. This will be described below. In this specification, an optical module refers to either an optical transmission module (optical transmitter) or an optical reception module (optical receiver). The optical transmission / reception module includes an optical transmission module and an optical reception module.

  FIG. 2 is a schematic diagram showing the connection between the flexible substrate 11 and the ceramic substrate 12 according to the embodiment, and shows the side surfaces of the flexible substrate 11 and its peripheral components. As shown in FIG. 2, the flexible substrate 11 is disposed between the optical receiving component 3 and the printed circuit board 2, and one end of the flexible substrate 11 is connected to the ceramic substrate 12 of the optical receiving component 3. . In practice, the optical receiving component 3 is fixed to the component tray 5 on the printed circuit board 2 as described above. However, for the sake of simplicity, the optical receiving component 3 and the printed circuit board 2 are shown apart from each other. ing. The present invention can be applied even when the optical receiving component 3 (or the optical transmitting component 4) is not fixed on the printed circuit board 2 and is not superimposed on each other.

  3A and 3B are a plan view and a bottom view, respectively, of the end portion of the flexible substrate 11 (upper substrate) according to the embodiment. 3A shows the front surface (upper surface) of the flexible substrate 11, and FIG. 3B shows the back surface (lower surface) of the flexible substrate 11. FIG. 4 is a plan view of the end portion of the ceramic substrate 12 (lower substrate) according to this embodiment, and shows the surface (upper surface) of the ceramic substrate 12. One or a plurality of transmission lines are formed on the flexible substrate 11. Here, as an example, a case where two pairs of differential transmission lines 20 are formed is shown. One differential transmission line includes a pair of signal wirings 21 </ b> A and 21 </ b> B formed on the front surface side of the flexible substrate 11 and a ground conductor layer 22 formed on the back surface side of the flexible substrate 11.

  An upper substrate terminal portion 31 is formed at an end portion of the flexible substrate 11. Here, the upper substrate terminal portion 31 is electrically connected via two pairs of differential transmission lines 20 and a transition region 24. It is connected. The upper substrate terminal portion 31 includes a plurality of grounding terminals and a plurality of signal terminals. Each terminal includes an upper substrate front surface terminal formed on the front surface side of the flexible substrate 11 and an upper substrate rear surface terminal formed on the back surface side of the flexible substrate 11 and forms a pair. Each pair of front surface terminals and rear surface terminals overlap in plan view, and a plurality of via holes 23 penetrating from the front surface to the rear surface of the flexible substrate 11 are formed in the overlapping region. The inner wall of the via hole 23 is subjected to metal plating or the like, and the front surface terminal and the back surface terminal are electrically connected via the plurality of via holes 23. As shown in FIG. 3A, on the surface of the end portion of the flexible substrate 11, a ground surface terminal 41 </ b> L and a pair of signal surface terminals in order from the left side to the right side in the horizontal direction (first direction) in the drawing in plan view. 42A, 42B, a ground surface terminal 41S, a pair of signal surface terminals 42A, 42B, and a ground surface terminal 41L are arranged side by side. Both ends of the plurality of surface terminals arranged in the horizontal direction are ground surface terminals 41L. In this embodiment, the plurality of surface terminals are all extended from the lower end of the flexible substrate 11, and the ground surface terminals 41L at both ends are equal in length along the vertical direction, and other surface terminals (signal surface terminals) 42A, 42B and the grounding surface terminal 41S) are equal in length, and the length of the grounding surface terminal 41L at both ends is longer than the length of the other surface terminals. As shown in FIG. 3B, the back surface of the end portion of the flexible substrate 11 has a ground back surface terminal 51L and a pair of signal back surfaces in order from the left side to the right side in the horizontal direction (first direction) in the drawing in plan view. Terminals 52B and 52A, grounding back surface terminal 51S, a pair of signal back surface terminals 52B and 52A, and grounding back surface terminal 51L are arranged side by side. Both ends of the plurality of back terminals arranged in the horizontal direction are ground back terminals 51L.

  A lower substrate terminal portion 32 is formed at the end of the ceramic substrate 12. The lower substrate terminal portion 32 includes a plurality of ground terminals and a plurality of signal terminals. Each terminal includes a lower substrate surface terminal formed on the surface side of the ceramic substrate 12. Each of the plurality of upper substrate rear surface terminals of the flexible substrate 11 is connected to overlap with the plurality of lower substrate surface terminals of the ceramic substrate 12. As shown in FIG. 4, the surface of the end portion of the ceramic substrate 12 has a ground surface terminal 61L, a pair of signal surface terminals 62A and 62B, and a ground in order from the left side to the right side in a plan view. A front surface terminal 61S, a pair of signal surface terminals 62A and 62B, and a ground surface terminal 61L are arranged side by side.

  As shown in FIGS. 3A and 3B, the upper substrate front surface terminal and the upper substrate rear surface terminal of the upper substrate terminal portion 31 are all from the lower end of the drawing of the flexible substrate 11 in the vertical direction (second direction) from the lower side to the upper side. It is stretched in a band shape (rectangular shape). Here, the first direction (horizontal direction in the figure) and the second direction (vertical direction in the figure) intersect each other. The first direction and the second direction preferably cross each other within a range of 90 ° ± 5 °, and more preferably are orthogonal. Similarly, as shown in FIG. 4, all the lower substrate surface terminals of the lower substrate terminal portion 32 extend the surface of the ceramic substrate 12 in a band shape from the upper side to the lower side.

  As shown in FIG. 3A, the signal surface terminal 42 </ b> A (42 </ b> B) has a predetermined width (for example, the first width), extends from the end (edge) of the flexible substrate 11 into a band shape, and in the transition region 24. The signal wiring 21A (21B) is further extended in a straight line with another predetermined width (for example, the second width) while narrowing the width. Further, as shown in FIG. 3B, the grounding back terminals 51 </ b> S and 51 </ b> L have a predetermined width, extend from the end (edge) of the flexible substrate 11 in a band shape, and are connected to the grounding conductor layer 22. Here, the terminal formed on a board | substrate is a metal terminal, and is formed with metal foil, such as copper foil. Similarly, the signal wiring and the ground conductor layer are similarly formed of a metal foil such as a copper foil. The signal wiring 21A (21B) and the signal surface terminal 42A (42B) shown in FIG. 3A are formed of a continuous metal foil. Similarly, in the ground conductor layer 22 shown in FIG. 3B, the grounding back terminals 51S and 51L are formed of a continuous metal foil. However, the terminal, the signal wiring, and the ground conductor layer are not limited to the metal foil, and may be other materials as long as sufficient conductivity is obtained. Further, as shown in FIGS. 3A and 3B, a resist 26 and a cover lay 25 are sequentially formed so as to cover the front surface and the back surface of the flexible substrate 11. Note that the resist 26 and the cover lay 25 are not formed in the region where the terminals are formed.

  The flexible substrate 11 and the ceramic substrate 12 are in physical contact (overlapping) between the upper substrate back surface terminal of the flexible substrate 11 and the lower substrate surface terminal of the ceramic substrate 12 via a conductive bonding material such as solder. Connected). Here, the upper substrate back surface terminal has a region overlapping with the corresponding lower substrate surface terminal, and this region is defined as a connection region. The connection area of the upper substrate back terminal is shown as a shaded area in FIG. 3B. In the present embodiment, the plurality of back terminals are extended from the lower end of the flexible substrate 11 like the front terminals, and the connection regions of the ground back terminals 51L at both ends are equal in length along the vertical direction. The connection areas of the back terminals (signal back terminals 52A and 52B and grounding back terminal 51S) are equal in length, and the length of the connection area of the grounding back terminal 51L at both ends is the connection of the other back terminal. It is longer than the length of the area. As shown in FIG. 3B, since the grounding back terminals 51S and 51L are connected to the ground conductor layer 22, even if the connection region connected to overlap with the lower substrate surface terminal is defined as the region of the upper substrate back surface terminal. Good. Further, the shape of the lower substrate front surface terminal of the ceramic substrate 12 is determined corresponding to the connection region of the upper substrate rear surface terminal.

  The main feature of the present invention is the structure of the first back surface terminal and the second back surface terminal that are included in the plurality of upper substrate back surface terminals and arranged adjacent to each other. Specifically, the connection of the second back surface terminals The position of the tip (second tip) of the second connection region that is the region is transmitted along the second direction from the position of the tip (first tip) of the first connection region that is the connection region of the first back terminal. It is on the track side. Here, although the first back terminal and the second back terminal extend along the second direction, the lower side of FIG. 3B is the lower substrate along the second direction (vertical direction of FIG. 3B). The upper side is the transmission line side. Considering the propagation direction of the electric signal, for example, it propagates from the lower board terminal of the lower board to the transmission line through the upper board terminal of the upper board. Or vice versa. That is, the first tip (second tip) is the end on the transmission line side of both ends in the second direction of the first connection region (second connection region). In general, when an external force is applied to the upper substrate from the outside, the vicinity of the tip of the connection region, that is, the boundary between the portion connected to the lower substrate and the portion not connected, is a location where the upper substrate is mainly bent. . However, in the present invention, when the second tip of the second back terminal is located closer to the wiring side in the second direction than the first tip of the first back terminal, an external force is applied to the upper substrate. Even in this case, it is possible to prevent stress from being concentrated as a bent portion of the upper substrate near the first tip of the first back surface terminal. When the tips of the connection regions of the plurality of upper substrate back surface terminals are at the same position (B shown in the figure) in the vertical direction (second direction) as in the upper substrate 111 according to the prior art shown in FIGS. 7A and 7B The bending portion of the upper substrate 111 is applied to the cross section passing through the tip of the connection region (B shown in the figure), and when a plurality of external forces S are applied, the bending stress concentrates linearly at the same position every time. Easy to break. In the upper substrate according to the present invention, when the external force S is applied a plurality of times, the positions of the fixed first tip (P1) and second tip (P2) are different, and how bending stress is applied. Due to the curved shape, when the external force S is applied a plurality of times, the stress is less likely to be concentrated and can be dispersed in a curved shape. Therefore, it is possible to realize a highly reliable optical module that suppresses disconnection of signal wiring and has a low failure rate.

  In the present embodiment, the second back terminal is, for example, the grounding back terminal 51L located at the left end shown in FIG. 3B among the plurality of upper substrate back terminals arranged in the horizontal direction, and the first back terminal is from the left end. This is the second signal rear surface terminal 52B. The position of the tip (second tip) of the connection area of the grounding back terminal 51L is shown as P2, and the position of the tip (first tip) of the connection area of the signal back terminal 52B is shown as P1.

  The signal back surface terminal 52B, which is the first back surface terminal, is electrically connected to the signal surface terminal 42B (first surface terminal) located second from the right end in FIG. The front surface terminal 42B is connected to the signal wiring 21B (first signal wiring). In order to stably obtain physical and electrical connection, it is necessary to secure a connection width of the upper substrate back surface terminal with a predetermined width or more. In contrast, the width of the signal wiring of the differential transmission line is determined by the wiring impedance, but is generally narrower than the width of the connection region (terminal). Therefore, as shown in FIG. 3A, the width of the transition region 24 is narrower than the width of the signal surface terminals 42A and 42B, and the signal wirings 21A and 21B are narrow. Further, the ground conductor layer 22 is provided on the back surface of the flexible substrate 11. However, since the signal terminal needs to be electrically insulated from the ground conductor layer 22, the ground conductor layer 22 is provided on the back surface for signal. A gap area where no conductor layer is provided exists between the tips of the signal back terminals 52A and 52B and the ground conductor layer 22 along the vertical direction of FIG. 3B. .

  Further, the vicinity of the tip of the signal surface terminals 42A and 42B (transition region 24) is a place where the possibility of disconnection is high, but in this embodiment, the second back terminal (the ground back terminal 51L) is the first. 2 The tip (P2) is at a position farther (further above) than the end (lower end) of the flexible substrate 11 compared to the first tip (P1) of the first back terminal (signal back terminal 52B). Therefore, when an external force is applied to the flexible substrate 11, the bending stress is suppressed from concentrating near the first tip, and disconnection in the signal wiring 20 and the transition region 24 near the upper substrate surface terminal portion in plan view is prevented. It is suppressed.

  Conversely, a greater bending stress is applied near the second tip of the second back terminal, but the positions of the fixed first tip (P1) and second tip (P2) are different. Since the bending stress is applied in a curved line, the stress is less concentrated and can be distributed in a curved line compared to the upper substrate 111 according to the prior art. Further, in the case of this embodiment, the grounding back surface terminal 51L is connected to the grounding conductor layer 22, and not only the tip of the second connection region but also a part of the right side of FIG. 22 is in contact. Therefore, even when an external force is applied to the flexible substrate 11 and a bending stress is applied to the vicinity of the tip, the possibility that the ground conductor layer 22 and the grounding back terminal 51L are disconnected is extremely suppressed. In addition, since there are a plurality of ground terminals connected to the ground conductor layer 22, the stability of the connection is ensured also from this viewpoint. Therefore, by selecting the second back terminal as the ground terminal, occurrence of disconnection at the connection location is suppressed.

  In the present embodiment, the second back terminal is a grounding terminal, but it goes without saying that the present invention is not limited to this. Compared with the signal wiring of the transmission line, the DC voltage wiring such as the power supply wiring has no restriction such as impedance matching, so that the wiring width can be sufficiently secured. Therefore, the upper wiring may include a DC voltage wiring, and the second back surface terminal may be a terminal electrically connected to the DC voltage wiring. The second back terminal may be a dummy terminal that is not connected to a wiring (such as a signal wiring) on the flexible substrate 11. In that case, the lower substrate surface terminal corresponding to the second back terminal is a dummy terminal.

  Of the upper substrate surface terminals of the flexible substrate 11, the signal surface terminals 42A and 42B play a role of electrically connecting the signal back terminals 52A and 52B and the signal wirings 21A and 21B. However, although the grounding surface terminals 41S and 41L are electrically connected to the grounding backside terminals 51S and 51L through the via holes 23, they do not play a role of being electrically connected to the grounding conductor layer 22. . However, in the embodiment, the upper substrate back surface terminal and the lower substrate surface terminal are joined by solder. At the time of joining, it is necessary to apply heat to dissolve the solder. However, by heating the upper substrate surface terminal, the upper substrate back surface terminal can be heated via the via hole 23. That is, the upper substrate front surface terminal also plays a role of transferring heat to the upper substrate rear surface terminal. Therefore, the length of the grounding back surface terminal 51L (second back surface terminal) is such that the grounding surface terminal 41L (second surface terminal) overlaps the grounding back surface terminal 51L (second back surface terminal) in plan view. It is desirable to make it longer corresponding to the thickness. In addition to electrical connection, from the viewpoint of heat conduction, the grounding surface terminal 41L (second surface terminal) and the grounding back surface terminal 51L (second back surface terminal) overlap with each other in plan view. The via hole 23 is preferably provided. Therefore, the upper substrate terminal portion 31 according to the embodiment has a desirable structure for transferring heat to the upper back surface terminal, for example, when connecting by solder or the like.

  In addition, each connection area | region of the some upper substrate back surface terminal which concerns on the said embodiment is extended in the 2nd direction from the lower end (edge) of the flexible substrate 11, and is long along the 2nd direction of a connection area | region. However, the tip of the connection region (end on the transmission line side) is located closer to the transmission line side. However, the position of the other end (end on the lower substrate side) of the connection region is different within a range in which electrical and physical connection between the upper substrate back surface terminal and the lower substrate surface terminal is ensured. Also good.

  Moreover, although the said embodiment has shown about the case where the one printed circuit board 2 and the one optical receiving component 3 are connected by the upper board | substrate terminal part 31 of the one flexible substrate 11, it is not limited to this. In order to connect a plurality of optical components (the optical receiving component 3 or the optical transmitting component 4) and one printed circuit board with one flexible substrate 11, a plurality of optical components corresponding to each of the plurality of optical components are provided on one flexible substrate 11. There may be a plurality of upper substrate terminal portions. Both the 1st back terminal and the 2nd back terminal concerning the present invention shall belong to one upper substrate terminal part connected to one optical component or a plurality of wirings extended from the optical component. On the contrary, the first back terminal belongs to a certain optical component or a certain upper substrate terminal connected to a plurality of wirings extending from the optical component, and the second back terminal is derived from another optical component or the other optical component. When belonging to another upper substrate terminal connected to a plurality of other extending wirings, even if the first back terminal and the second back terminal are arranged next to each other, they are not included in the present invention And

  In the embodiment, as shown in FIGS. 3A and 3B, coverlays 25 are formed on the front surface and the back surface of the flexible substrate 11. The coverlay 25 is a protective layer that protects the front surface (back surface) of the flexible substrate, and a resin such as polyimide is used as a material. The cover lay 25 not only electrically cuts off the electrical wiring (ground conductor layer and signal wiring) on the substrate from the outside, but can also physically protect the flexible substrate 11 against bending. In this embodiment, the cover lay 25 is formed on each of the front and back surfaces of the flexible substrate 11, but is formed except for the region where the upper substrate front surface terminal and the upper substrate back surface terminal are formed. In the embodiment, the plurality of upper substrate front surface terminals and the plurality of upper substrate rear surface terminals (connection regions thereof) overlap each other in plan view. Therefore, the coverlay 25 formed on the surface of the flexible substrate 11 is formed on the surface excluding at least the first connection region in plan view.

  Since the cover lay 25 is affixed and fixed with an adhesive or the like, in consideration of manufacturing errors, the outer edge of the cover lay 25 and the upper substrate surface terminal (tip) which is a region to which heat is applied during solder connection. And are separated from each other. Therefore, in the present embodiment, as shown in FIG. 3A, the lower end of the cover lay 25 (outer edge, the lower end shown in the figure) is predetermined from the left end of the left side of FIG. The upper side (transmission line side) is extended to the right with a width of 1 mm, bent at a right angle between the grounding surface terminal 41L at the left end and the adjacent signal surface terminal 42A, and a predetermined length from the tip of the signal surface terminal 42A. Extends downward to the upper side with a width. Such a portion is located below the front end of the grounding surface terminal 41L along the vertical direction, and is indicated by A in FIG. 3A. Then, it is bent at a right angle at such a location, and is further extended rightward with a predetermined width from the tips of the signal surface terminals 42A and 42B and the ground surface terminal 41S. Bent at a right angle between the signal surface terminal 42B (first surface terminal) second from the right end and the ground surface terminal 41L (second surface terminal) at the right end, and a predetermined value is applied from the tip of the ground surface terminal 41L. It extends upward to a location that is on the upper side with a width, bends at a right angle, and extends upward on the right side with a predetermined width from the tip of the grounding surface terminal 41L on the right end. Here, in plan view, when attention is paid to the position in the lateral direction (first direction) of the lower end of the cover lay 25, the portions of the ground surface terminal 41L at both ends are more than the portions of the other upper substrate surface terminals. It is on the upper side (transmission line side). Then, in plan view, the portion of the lower end of the cover lay 25 at the other upper substrate surface terminal is the tip (second tip) of the ground surface terminal 41L at both ends along the vertical direction (second direction). It is on the lower side (lower substrate side).

  Therefore, the cover lay 25 is lower than the tip of the right-side grounding surface terminal 41L (second surface terminal) in plan view with respect to the second signal surface terminal 42B (first surface terminal) from the right end. It extends to the side (the lower substrate side along the second direction). Here, since the upper substrate front surface terminal overlaps with the upper substrate rear surface terminal (connection region thereof) in a plan view, the coverlay 25 is a second connection in a plan view with respect to the first connection region. It extends from the second tip of the region to the lower side (the lower substrate side along the second direction). According to the present invention, in the vicinity of the first tip of the first back terminal, the portion where the flexible substrate 11 is actually bent moves further upward (on the transmission line side) than the first tip, but this portion is covered with the cover lay 25. I can do it.

  In the above embodiment, the left end grounding back surface terminal 51L shown in FIG. 3B has been described as the second back surface terminal, and the second signal back surface terminal 52B from the left end has been described as the first back surface terminal. Never happen. It goes without saying that the grounding back terminal 51L at the right end may be the second back terminal, and the second signal back terminal 52B from the right end may be the first back terminal. Further, the grounding back terminal 51L disposed at the left end (one end) is used as a second back terminal, and the ground back terminal 51L disposed at the right end (one end is the other end) is the fourth back terminal. With the back terminal as the back terminal and the second signal back terminal 52A from the right end adjacent to this as the third back terminal, the position of the tip (fourth tip) of the connection area (fourth connection area) of the fourth back terminal is It is desirable to be on the upper side (transmission line side along the second direction) from the position of the connection region (third connection region) of the three back terminals.

  Further, like the plurality of upper substrate back surface terminals according to the embodiment, the positions (P2 shown in FIG. 3B) of the connection regions of the upper substrate back surface terminals (grounding back surface terminals 51L) at both ends are both on the other upper side. It is more desirable to be above the entire tip of the connection region at the tip position (P1 shown in FIG. 3B) of the connection region of the substrate back surface terminal. By adopting such a structure, disconnection in all signal wirings arranged on the flexible substrate 11 can be suppressed. When the external force S shown in FIG. 2 is applied to the flexible substrate 11, an approximate location where the bending stress of the flexible substrate 11 is applied is shown as a curve B in FIG. 3A. As described above, the bending stress applied to the flexible substrate 11 is easily dispersed by the external force S applied to the flexible substrate 11 a plurality of times.

  3A, in the region between the ground surface terminals 41L at both ends, the lower end of the cover lay 25 is at the position indicated by A in FIG. 3A, and the bent portion of the flexible substrate 11 indicated by curve B in FIG. Of these, all portions crossing the signal wiring are covered with the coverlay 25. That is, in the flexible substrate 11 according to the present embodiment, the bent portion (B of the flexible substrate 11 is located on the transmission line side (the right side of FIG. 2, the upper side of FIGS. 3A and 3B) from the lower end of the cover lay 25 shown in FIG. ) Has occurred. In the upper substrate 111 according to the prior art shown in FIG. 7A, a cover lay 125 is formed, but the lower end of the cover lay 125 is at the position indicated by A in FIG. 7A and is above the tip of the connection region, The coverlay 125 does not cover the bending place (B in FIG. 7A) of the upper substrate 111. The position A which is the lower end of the cover lay 125 is indicated as (A) in FIG.

  Here, the cover lay 25 formed on the front surface of the flexible substrate 11 has been described, but the same applies to the cover lay 25 formed on the back surface of the flexible substrate 11. Further, it is more desirable that cover lays 25 are formed on both sides. The protective layer according to the present invention is not limited to the cover lay 25, and is a protective film that covers the surface of the substrate, and physically protects electrical wiring and the like formed on the substrate against bending of the substrate. Anything is acceptable. In consideration of manufacturing errors, the outer edge of the cover lay 25 cannot be extended to the vicinity of the plurality of upper substrate front surface terminals (upper substrate back surface terminals), and a gap region must be provided between the cover lay 25 and the terminals. I don't get it. A resist 26 is provided to protect a part of the gap area. The resist 26 is an insulating film, and can electrically shield the electrical wiring (ground conductor layer and signal wiring) on the substrate surface from the outside. However, the resist 26 hardly contributes to physically protecting the flexible substrate 11 against bending. However, since the fabrication accuracy of the resist 26 is better than that of the cover lay 25, a part of the gap region between the cover lay 25 and the terminal can be further electrically protected. 3A and 3B show a resist 26 formed in a part of a gap area between the cover lay 25 and the terminal as a shaded area.

[Second Embodiment]
5A and 5B are a plan view and a bottom view, respectively, of the end portion of the flexible substrate 11 (upper substrate) according to the second embodiment of the present invention. FIG. 6 is a plan view of an end portion of the ceramic substrate 12 (lower substrate) according to the embodiment. Although the structure of the edge part of the flexible substrate 11 which concerns on the said embodiment, and the edge part of the ceramic substrate 12 differs from 1st Embodiment, it is the same about other than that. Specifically, the structure of the ground terminal located between the two pairs of transmission lines in the flexible substrate 11 is different from that of the first embodiment, and accordingly, the structure of the ground terminal of the ceramic substrate 12 is the first. This is different from the embodiment. As shown in FIGS. 5A and 5B, the grounding surface terminal 41L and the grounding back surface terminal 51L located at the center of the drawing extend to the same length as the grounding terminals at both ends. Accordingly, as shown in FIG. 6, the grounding surface terminal 61L located at the center of the drawing extends to the same length as the grounding surface terminals 61L at both ends. Accordingly, the lower end of the resist 26 and the lower end of the cover lay 25 formed on both surfaces of the flexible substrate 11 are moved upward so as not to be formed on the terminals.

  By making all the grounding terminals of the flexible substrate 11 longer than the signal terminals, the physical connection as well as the electrical connection between the flexible substrate 11 and the ceramic substrate 12 can be further stabilized. In addition, when an external force S is applied to the flexible substrate 11, the bending stress generated in the terminal portion of the flexible substrate 11 can be concentrated at the tip of the connection region of the back terminal for grounding. It can be further suppressed. In the flexible substrate 11 according to the second embodiment, not only the grounding back terminal 51L at both ends but also the central grounding back terminal 51L is the second back terminal, and any of the adjacent signal back terminals is the first. It can be a back terminal. Thus, the second back terminal is not limited to both ends, and the effect of the present invention can be obtained. Moreover, four back terminals arranged in order from the left end (right end) among the plurality of upper substrate back terminals shown in FIG. 5B are sequentially designated as a second back terminal, a first back terminal, a third back terminal, and a fourth back terminal. Also good.

  The optical transceiver module 100 and the flexible substrate 11 according to the embodiment of the present invention have been described above. The present invention is not limited to the above embodiment and can be widely applied. In the above embodiment, the front surface terminal and the back surface terminal of the upper substrate overlap each other. That is, in the plan view, the area of the front surface terminals corresponds to the area of the back surface terminals. In plan view, the area of each back terminal of the upper substrate and the area of the corresponding front surface terminal of the lower substrate coincide. However, it is not limited to these. The front surface terminal only needs to be electrically connected to the rear surface terminal, and the front surface terminal only needs to overlap at least a part of the rear surface terminal in plan view in order to secure a connection means such as a via hole.

  Moreover, in the said embodiment, although all the shapes of the terminal are made into strip | belt shape (rectangular shape), it is not limited to this, A several surface terminal (back surface terminal) is located in a line along the 1st direction in order. Any shape that extends in the second direction (in short, an elongated shape) may be used so that it can be arranged. Even in such a case, if the width of the terminal is the widest length along the direction (for example, the first direction) orthogonal to the second direction of the shape extending in the second direction, The terminal tip may be the position closest to the transmission line along the second direction.

  The upper substrate according to the present invention is optimally a flexible substrate, but is not limited to this, and may be another wiring substrate. When the upper substrate 111 according to the related art shown in FIGS. 7A and 7B is a flexible substrate, the flexibility of the flexible substrate is reduced as the number of transmission lines formed on the upper substrate 111 is increased. Becomes more concentrated, and the signal wiring is less likely to break. In order to solve such a problem, the flexibility of the flexible substrate may be improved, and it is conceivable to reduce the width of the flexible substrate and to reduce the thickness of the flexible substrate. However, since it is necessary to ensure the terminal width and pitch at a predetermined value or more from the viewpoint of desired characteristics and manufacturing accuracy, there is a limit to narrowing the width of the flexible substrate. Further, if the thickness of the flexible substrate is reduced, the wiring width of the signal wiring is reduced in order to achieve a desired impedance. However, there is a limit in manufacturing accuracy. Therefore, when increasing the number of transmission lines to be formed while ensuring the width and thickness of the flexible substrate necessary for production, the present invention has a special effect.

  In the above embodiment, the case where two pairs of differential transmission lines are formed on the flexible substrate 11 has been described. However, the present invention is not limited to this. Instead of the differential transmission line, another transmission line, for example, a single transmission line may be used. In that case, one signal line is formed on the surface of the flexible substrate 11 in one transmission line. The number of transmission lines formed on the flexible substrate 11 is not limited to two, and the effect of the present invention is enhanced when many transmission lines are formed on the upper substrate.

  The upper substrate and the lower substrate according to the present invention are respectively a flexible substrate and a ceramic substrate of an optical component, but the present invention is not limited to these, and the present invention is not limited to a connection point between a transmission line and a transmission line. The present invention can be widely applied to connection points between transmission lines and optical components. For example, you may apply this invention to the connection location of the flexible substrate 11 and the printed circuit board 2 which are shown in FIG. Further, both the upper substrate and the lower substrate may be wiring substrates such as flexible substrates. Here, for the sake of simple explanation, the two substrates are referred to as an upper substrate and a lower substrate in view of the fact that the two substrates are connected by overlapping. The vertical relationship between the two substrates is merely defined for convenience. More strictly, two substrates may be used as the first substrate and the second substrate regardless of the vertical direction. In addition, in the microstrip line, of the two surfaces of the dielectric layer, the surface on which the signal wiring is formed is conventionally the front surface (upper surface) and the surface on which the ground conductor layer is formed is the back surface (lower surface). For convenience, of the two surfaces of the upper substrate, the surface on which the signal wiring is formed is the front surface, and the surface on which the ground conductor layer is formed is the back surface. More strictly, regardless of the definition of the front and back surfaces, of the two surfaces of the upper substrate, the side facing the lower substrate may be the first surface and the opposite side of the second surface may be the second surface. The same applies to the two surfaces of the lower substrate.

  The optical module according to the embodiment is an optical receiver module, and the optical transceiver module 100 according to the embodiment is an optical transceiver module including the optical receiver module according to the embodiment and a known optical transmitter module. It is not limited to. The optical module according to the present invention may be either a single unit of an optical transmitter or an optical receiver, or the optical transmission / reception module according to the present invention includes the optical transmission module according to the present invention and a known optical reception module. The optical transmission module according to the present invention and the optical reception module according to the present invention may be provided.

  Furthermore, in the optical module according to the above-described embodiment, the case where the lengths of the grounding surface terminals 41L at the both ends are aligned has been described, but the end of the grounding surface terminal 41L on the transmission line side in a plan view As long as the surface terminals 41A and 42B are located closer to the transmission line than the transmission line side ends, the length of the grounding surface terminal 41L at both ends and the position of the grounding surface terminal 41L on the transmission line side are different. The effects of the invention can be obtained.

  DESCRIPTION OF SYMBOLS 1 Case, 2 Printed circuit board, 3 Optical receiving component, 4 Optical transmitting component, 5 Component tray, 6 Optical receptacle, 7 Optical fiber tray, 8, 10 Electric high frequency component, 9 Card edge connector, 11, 91 Flexible substrate, 12 ceramic substrate, 20 differential transmission line, 21A, 21B, 121A, 121B signal wiring, 22, 122 ground conductor layer, 23, 123 via hole, 24, 124 transition region, 25, 125 coverlay, 26 resist, 31, 131 Upper board terminal section, 32, 132 Lower board terminal section, 41L, 41S, 61L, 61S, 141 Ground surface terminal, 42A, 42B, 62A, 62B, 142A, 142B Signal surface terminal, 51L, 51S, 151 Ground Back terminal, 52A, 52B, 152A, 152B Signal back terminal 92 optical fiber, 100 optical transceiver module.

Claims (11)

One or a plurality of transmission lines, and a plurality of upper substrate rear surface terminals formed on the back surface side, which are electrically connected to the one or more transmission lines, arranged in a first direction in plan view, and Including an upper substrate;
A plurality of lower substrate surface terminals connected to overlap each of the plurality of upper back terminals, and formed on the front surface side; a lower substrate; and
An optical module comprising:
The plurality of upper substrate back surface terminals are adjacent to each other, and extend in a second direction intersecting the first direction from the lower substrate side to the transmission line side, and a first back surface terminal and a second back surface Including terminals,
The first back surface terminal has a first connection region that is a region overlapping with the corresponding lower substrate surface terminal,
The second back surface terminal has a second connection region that is a region overlapping with the corresponding lower substrate surface terminal,
The position of the second tip on the transmission line side of the second connection region is closer to the transmission line side along the second direction than the position of the first tip on the transmission line side of the first connection region. It is in,
An optical module characterized by that. The optical module according to claim 1,
The upper substrate is
A first surface terminal that is formed on the front surface side to overlap with at least a portion of the first back surface terminal in plan view and electrically connected to the first back surface terminal;
A first signal line of the transmission line formed on the front side and electrically connected to the first surface terminal;
Further including
An optical module characterized by that. The optical module according to claim 2,
A width of the first signal wiring is narrower than a width of the first surface terminal;
An optical module characterized by that. An optical module according to any one of claims 1 to 3,
The upper substrate further includes a protective layer formed on the surface excluding at least the first connection region in plan view,
The protective layer is further on the lower substrate side than the second tip of the second connection region along the second direction in plan view with respect to the first tip of the first connection region. ,
An optical module characterized by that. An optical module according to any one of claims 1 to 4,
The second back terminal is disposed at one end of the plurality of upper substrate back terminals arranged in the first direction,
The plurality of upper substrate back surface terminals include a third back surface terminal and a fourth back surface terminal, both extending the second direction from the lower substrate side to the transmission line side,
The fourth back terminal is disposed at an end on the other side of the plurality of upper substrate back terminals, the one side,
The third back surface terminal has a third connection region that is a region overlapping with the corresponding lower substrate surface terminal,
The fourth back surface terminal has a fourth connection region that is a region overlapping with the corresponding lower substrate surface terminal,
The position of the fourth tip on the transmission line side of the fourth connection region is closer to the transmission line side along the second direction than the position of the third tip on the transmission line side of the third connection region. It is in,
An optical module characterized by that. An optical module according to any one of claims 1 to 5,
The upper substrate is
A second surface terminal that is formed on the front surface side and overlapped with at least a part of the second back surface terminal in plan view, and is electrically connected;
An optical module characterized by that. The optical module according to claim 6,
The upper substrate is
In the region where the second back surface terminal and the second surface terminal overlap in plan view, further includes a via hole penetrating from the surface of the upper substrate to the back surface,
An optical module characterized by that. An optical module according to any one of claims 1 to 7,
The upper substrate is
Further including a ground conductor layer of the transmission line formed on the back side,
The second back terminal is electrically connected to the ground conductor layer;
An optical module characterized by that. An optical module according to any one of claims 1 to 7,
The upper substrate is
DC voltage wiring further,
The second back terminal is electrically connected to the DC voltage wiring;
An optical module characterized by that. An optical transceiver module comprising the optical module according to any one of claims 1 to 9 and another optical module,
Either one of the optical module and the other optical module is an optical transmitter, and the other is an optical receiver.
An optical transceiver module characterized by the above. One or more transmission lines;
A plurality of upper substrate rear surface terminals that are electrically connected to the one or more transmission lines, arranged in a first direction in plan view, and formed on the rear surface side;
A flexible substrate comprising:
The plurality of upper substrate rear surface terminals are connected to overlap each of a plurality of lower substrate surface terminals formed on the surface side of another substrate,
The plurality of upper substrate back surface terminals are adjacent to each other, and extend in a second direction intersecting the first direction from the other substrate side to the transmission line side, and a first back surface terminal and a second back surface Including terminals,
The first back surface terminal has a first connection region that is a region overlapping with the corresponding lower substrate surface terminal,
The second back surface terminal has a second connection region that is a region overlapping with the corresponding lower substrate surface terminal,
The position of the second tip on the transmission line side of the second connection region is closer to the transmission line side along the second direction than the position of the first tip on the transmission line side of the first connection region. It is in,
A flexible substrate characterized by the above.

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