JP7559471B2 - Optical Element Module - Google Patents

Description

The present invention relates to an optical element module.

In recent years, optical element modules have been put to practical use in which a side-view type optical element package that emits light horizontally relative to the mounting surface is mounted on a mounting substrate. Such optical element packages typically include a first surface that is coupled to the light-emitting element and a second surface that is parallel to the first surface, and are provided with a body substrate that is substantially rectangular and has electrodes on the first and second surfaces. In addition, the electrodes on the second surface are connected to the mounting substrate by solder.

In such optical element modules, when mounting the optical element package, the surface tension of the molten solder as it solidifies can cause the optical element package to stand up from the mounting substrate (the so-called Manhattan phenomenon).

Conventionally, optical element modules have been disclosed that attempt to suppress this phenomenon of the optical element package rising up. Patent Document 1 discloses a side-view LED module (optical element module) that minimizes the exposed area of the solder that joins the side-view LED package (optical element package) and the mounting substrate by providing a concave electrode on the second surface. Patent Document 2 discloses a side-view type light emitting device in which solder is also formed on the mounting substrate in a through hole provided by cutting out the long side of the substrate (body substrate) of the light emitting device (optical element package).

JP 2019-176133 A JP 2018-49953 A

However, in the configuration described in Cited Document 1, it is necessary to provide an opening on the second surface of the body portion (body substrate) so that the concave electrode has a concave space. Also, in the configuration described in Cited Document 2, it is necessary to provide a through hole in the substrate so that the cross-sectional shape of the through hole in the substrate long side direction matches the land pattern in which the solder is formed. Thus, in the conventional technology, in order to prevent the optical element package from standing up, it is necessary to process the body substrate to provide an opening or through hole, etc., which causes a problem of a complicated manufacturing process for the body substrate.

One aspect of the present invention was made in consideration of the above problems, and its purpose is to provide an optical element module that can suppress the phenomenon of the optical element package standing up with a simpler configuration, without complex processing of the body substrate.

In order to solve the above problem, an optical element module according to one aspect of the present invention includes a mounting substrate, and a side-view type optical element package (chip) mounted on the mounting substrate, the optical element package including an optical element, a body substrate including a first surface bonded to the optical element, a second surface parallel to the first surface, and a third surface perpendicular to the first and second surfaces and facing the mounting substrate, the body substrate having electrodes on the first and second surfaces, and a solder portion connecting a pad of the electrode on the second surface to a pad formed on the mounting substrate, where h is the height of the body substrate from the third surface and h is the height of the pad of the electrode on the second surface from the third surface, and h≦1/2·H.

The above configuration effectively prevents the optical element package from standing up due to the surface tension generated when the molten solder in the solder portion solidifies during the reflow process.

The body substrate of the optical element module may include a fourth surface and a fifth surface that are perpendicular to the first surface, the second surface, and the third surface and parallel to each other, and the pad formed on the mounting substrate may have a first region formed along an edge of the second surface that faces the third surface, and a second region connected to the first region and formed along an edge of the fourth surface or the fifth surface that faces the third surface.

According to the above configuration, a portion of the melted solder in the reflow process flows into the second region of the mounting board side pad. This temporarily reduces the amount of melted solder in the first region, and reduces the surface tension in the direction in which the optical element package stands up when the melted solder solidifies. This makes it possible to more effectively suppress the phenomenon in the reflow process in which the optical element package stands up due to the surface tension when the melted solder solidifies. The solder that has flowed into the second region eventually returns to the first region 101a where the electrode pad is located, and then solidifies. Therefore, electrical continuity is established between the electrode pad and the mounting board side pad through a sufficient amount of solder.

The first region of the optical element module may have an overlapping portion that overlaps with the body substrate in a plan view. According to the above configuration, the solder on the pad formed on the mounting substrate melts in the reflow process, and the flux contained in the solder penetrates into the overlapping portion where the first region and the body substrate overlap. This allows the optical element package to adhere closely at the overlapping portion, making it possible to more effectively suppress the phenomenon of the optical element package standing up.

The pad formed on the mounting substrate of the optical element module may be L-shaped in a plan view. This makes it easy to realize a mounting substrate side pad having a first region and a second region.

An optical element package according to one aspect of the present invention is a side-view type optical element package mounted on a mounting substrate, and includes an optical element, a body substrate including a first surface coupled to the optical element, a second surface parallel to the first surface, and a third surface perpendicular to the first and second surfaces and facing the mounting substrate, the body substrate having electrodes on the first and second surfaces, the pads of the electrodes on the second surface are connected to pads formed on the mounting substrate by solder parts, and where the height of the second surface from the third surface is H and the height of the pads of the electrodes on the second surface from the third surface is h, h≦1/2·H.

As a result, as already explained for the optical element module, even if the surface tension of the molten solder solidifying during the reflow process acts on the optical element package, it is less likely to stand up.

A manufacturing method of an optical element module according to one aspect of the present invention is a manufacturing method of an optical element module in which a side-view type optical element package is mounted on a mounting substrate, the optical element package comprising an optical element, a body substrate having electrodes on the first and second surfaces, the body substrate including an optical element, a first surface bonded to the optical element, a second surface parallel to the first surface, and a third surface perpendicular to the first and second surfaces and facing the mounting substrate, the body substrate including electrodes on the first and second surfaces, the body substrate including a height H from the third surface and a height h from the third surface of the pad of the electrode on the second surface, the body substrate including a pad of the electrode on the second surface so that h≦1/2·H, the pad of the electrode on the second surface is formed on the mounting substrate, the pad of the electrode on the second surface is formed on the mounting substrate, the pad of the electrode on the second surface is formed on the mounting substrate, the pad of the electrode on the second surface is aligned with the pad of the mounting substrate in a plan view, and the solder is melted by heat treatment, and the pad of the electrode on the second surface is connected to the pad of the mounting substrate by the solder.

According to one aspect of the present invention, it is possible to suppress the phenomenon of the optical element package standing up with a simpler configuration without performing complex processing on the body substrate.

1 is a plan view of an optical element module according to an embodiment of the present invention; FIG. 2 is a perspective view of a portion of the optical element module where an optical element package is mounted; 4 is a rear view of a portion of the optical element module where an optical element package is mounted. FIG. 4 is a schematic cross-sectional view of a portion of the optical element module where an optical element package is mounted. FIG. 13 is a top view of an optical element package mounting portion in an optical element module according to another embodiment of the present invention. FIG. 5A to 5C are process diagrams illustrating a method for manufacturing the optical element module. FIG. 11 is a top view of an optical element package mounting portion in an optical element module according to still another embodiment of the present invention.

Below, an embodiment of one aspect of the present invention (hereinafter also referred to as "the present embodiment") will be described with reference to the drawings. However, the present embodiment described below is merely an example of the present invention in every respect. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention. In other words, in implementing the present invention, a specific configuration according to the embodiment may be appropriately adopted.

§1 Application Example The optical element module 1, optical element package 20, and mounting substrate 10 according to this embodiment can be applied to a toner concentration sensor used in image forming devices such as copiers, printers, facsimiles, etc. In the toner concentration sensor, an optical element package 20 including a light-emitting element and an optical element package 20 including a light-receiving element are mounted on a mounting substrate.

The optical element module 1, optical element package 20, and mounting substrate 10 can suppress the phenomenon in which the optical element package 20 stands up from the mounting substrate due to the surface tension when the molten solder solidifies during mounting. Therefore, by applying the optical element module 1, optical element package 20, and mounting substrate 10 to a toner concentration sensor, it is possible to prevent an increase in the manufacturing cost of the toner concentration sensor due to the phenomenon in which the optical element package 20 stands up.

§2 Configuration Example [Embodiment 1]
(Configuration of Optical Element Module 1)
Fig. 1 is a plan view of an optical element module 1 according to this embodiment. Fig. 2 is a perspective view of a portion of the optical element module 1 according to this embodiment where an optical element package 20 is mounted. As shown in Figs. 1 and 2, the optical element module 1 includes a mounting substrate 10, a plurality of optical element packages 20, and a solder portion 30.

On the mounting substrate 10, a pair of mounting substrate side pads 11 (pads formed on the mounting substrate) is formed for one optical element package 20. The mounting substrate side pads 11 are provided at the location where the optical element package 20 is mounted. The mounting substrate side pads 11 are provided at both ends along the lower side (side on the third surface side) 21f of the second surface 21b of the body substrate 21, which will be described later, in correspondence with the electrode pads 25a, which will be described later. In this embodiment, the mounting substrate side pads 11 are rectangular in shape.

The optical element package 20 is a side-view type package mounted on the mounting substrate 10. The optical element package 20 is, for example, a CSP (Chip-Size Package) that is approximately the same size as the semiconductor chip contained therein. The optical element package 20 includes a body substrate 21, an optical element 22, and a molded resin 27.

The body substrate 21 is a member having a substantially rectangular shape. The body substrate 21 includes a first surface 21a that is bonded to the optical element 22, a second surface 21b that is parallel to the first surface 21a, and a third surface 21c that is perpendicular to the first surface 21a and the second surface 21b and faces the mounting substrate 10. In the following description, the side of the optical element package 20 on which the first surface 21a is located is referred to as the front, the side on which the second surface 21b is located is referred to as the rear, the left side facing the rear is referred to as the left side, and the right side is referred to as the right side.

The body substrate 21 also has two through holes 23 arranged in parallel in the left-right direction, penetrating between the first surface 21a and the second surface 21b. The body substrate 21 also includes a fourth surface 21d and a fifth surface 21e that are perpendicular to the first surface 21a, the second surface 21b, and the third surface 21c and parallel to each other. In the example of FIG. 2, the fourth surface 21d is located on the left and the fifth surface 21e is located on the right. The body substrate 21 is, for example, a glass epoxy substrate.

A pair of first electrodes 24 (electrodes on the first surface) is provided on the first surface 21a. A pair of second electrodes 25 (electrodes on the second surface) is provided on the second surface 21b. The first electrodes 24 and the second electrodes 25 are connected via third electrodes 26 provided in each of the two through holes 23. In addition, on the first surface 21a, the pair of first electrodes 24 and the electrodes of the optical element 22 are connected. Furthermore, on the second surface 21b, the pair of second electrodes 25 and the pair of electrodes of the mounting substrate 10 are connected. Specifically, the electrode pads 25a (pads of the electrodes on the second surface) of the pair of second electrodes 25 and the mounting substrate side pads 11 of the pair of electrodes on the mounting substrate 10 side are connected via the solder parts 30. The detailed configuration of the electrode pads 25a will be described later with reference to Figures 2 and 3.

The optical element 22 is, for example, a light-emitting element such as a light-emitting diode. The optical element 22 also includes a light-receiving element such as a phototransistor or a photodiode.

The molded resin 27 is provided to cover the optical element 22. The molded resin 27 provides physical and chemical protection to the optical element 22.

Figure 3 is a rear view of the portion of the optical element module 1 where the optical element package 20 is mounted. As shown in Figure 3, the pair of electrode pads 25a are rectangular pads located at both the left and right ends of the second surface 21b. The electrode pads 25a are also provided on the lower part of the second surface 21b. The electrode pads 25a are rectangular areas to which solder, which will be described later, is attached.

Figure 4 is a schematic cross-sectional view of the optical element module 1 where the optical element package 20 is mounted. With reference to Figure 4, the relationship between the height H from the third surface 21c of the body substrate 21 and the height h of the electrode pad 25a from the third surface 21c will be described. Note that in this embodiment, the height H from the third surface 21c of the body substrate 21 is also the height of the second surface 21b from the third surface 21c.

The solder portion 30 is formed when the solder formed on the mounting board pad 11 melts, becomes fluid, and finally solidifies during the reflow process. Typically, cream solder containing an alloy and flux is used as the solder formed on the mounting board pad 11. As shown in FIG. 4, the solder portion 30 forms a curved surface (fillet portion) from the rear end of the mounting board pad 11 to the upper end of the electrode pad 25a.

In the reflow process, the surface tension γ acts on the optical element package 20 when the molten solder solidifies. The surface tension γ acting on the optical element package 20 acts in the tangent direction of the fillet portion (the direction forming the fillet angle α backward with respect to the second surface 21b) at the upper end (position of height h) of the electrode pad 25a. That is, the horizontal component of the surface tension γ is expressed as γ·sinα. Here, due to the surface tension γ, a rotational moment M acts in the direction in which the optical element 22 stands up, with the lower side 21f of the second surface 21b as the fulcrum P. Therefore, the higher the height h of the electrode pad 25a, the larger the rotational moment M becomes, since the horizontal component γ·sinα of the surface tension γ acts at a position farther away from the fulcrum P. That is, the higher the height h of the electrode pad 25a, the easier it is for the optical element package 20 to stand up.

Therefore, in the optical element package 20, the electrode pads 25a are provided so that the height h of the electrode pads 25a is 50% or less (h≦1/2·H) of the height H of the second surface 21b, which is the height of the body substrate 21. This effectively prevents the optical element package 20 from rising due to the surface tension γ when the molten solder in the fillet portion (solder) solidifies during the reflow process. Furthermore, taking into account the balance between strength and moment, it is preferable that the electrode pads 25a are provided so that the height h of the electrode pads 25a is 30% or less of the height H of the second surface 21b. This effectively prevents the optical element package 20 from rising, and ensures the connection strength of the fillet portion.

[Embodiment 2]
Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals are given to members having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

Figure 5 is a top view of the mounting portion of the optical element package 20 in an optical element module 100 according to another embodiment of the present invention. The optical element module 100 differs from the optical element module 1 in that it includes mounting board side pads 101 instead of mounting board side pads 11.

As shown in FIG. 5, the pair of mounting board side pads 101 are located at both ends along the lower edge (edge on the third surface side) 21f of the second surface 21b. The pair of mounting board side pads 101 have a first region 101a formed along the lower edge 21f of the second surface 21b, and a second region 101b connected to the first region 101a and formed along the lower edge (edge on the third surface side) 21g or 21h of the fourth surface 21d or fifth surface 21e. In this embodiment, the mounting board side pad 101 has an L-shape in a plan view.

The solder formed on the mounting board side pad 101 melts in the reflow process and flows to the second region 101b of the mounting board side pad 101. That is, the solder flows in the direction indicated by the arrow A in FIG. 5. This reduces the surface tension γ in the direction in which the optical element package 20 stands up. Therefore, the phenomenon in which the optical element package 20 stands up due to the surface tension γ of the solder in the reflow process can be more effectively suppressed. In addition, the solder that has flowed to the second region 101b solidifies after returning to the first region 101a where the electrode pad 25a is located. Therefore, the electrode pad and the mounting board side pad are electrically connected by a sufficient amount of solder.

At this time, the mounting board side pad 101 is arranged so that there is a gap between the lower edge 21g or 21h of the fourth surface 21d or the fifth surface 21e and the second region 101b. This makes it possible to prevent the solder that has flowed into the second region 101b from adhering to the fourth surface 21d or the fifth surface 21e.

In addition, only one of the pair of mounting board side pads may be configured to have the first region 101a and the second region 101b.

[Embodiment 3]
Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals are given to members having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

In this embodiment, a method for manufacturing the optical element module 1 will be described. FIG. 6 is a process diagram showing the method for manufacturing the optical element module 1. With reference to FIG. 3 to FIG. 5, a method for manufacturing the optical element module 1 in which a side-view type optical element package 20 is mounted on a mounting substrate 10 will be described.

As shown in FIG. 3, in the optical element package 20, the electrode pad 25a is provided on the second surface 21b (P1 in FIG. 6). Here, the electrode pad 25a is provided on the second surface 21b so that the height h of the electrode pad 25a is 50% or less of the height H of the body substrate 21 (h≦1/2·H).

Furthermore, mounting board side pads 11 (101) that are connected to electrode pads 25a are formed on the mounting board 10 (P2). Here, the mounting board side pads 11 (101) are formed so that the mounting board side pads 11 (101) are provided at least in positions that correspond to the electrode pads 25a on the mounting board 10. For convenience, process P2 is described after process P1, but since processes P1 and P2 are each performed in separate processes, this does not dictate the order of the processes.

Next, solder is formed on the mounting board pads 11 (P3). Next, the optical element package 20 is placed by aligning the electrode pads 25a and the mounting board pads 11 (101) in a plan view (P4). Next, the solder is melted by heat treatment (reflow process), and the electrode pads 25a and the mounting board pads 11 (101) are connected by the solder (P5). In this way, the optical element package 20 is mounted on the mounting board 10.

[Embodiment 4]
Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals are given to members having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

Figure 7 is a top view of the portion of the optical element module where the optical element package 20 is mounted. The optical element module 102 differs from the optical element module 100 in that it includes mounting board side pads 103 instead of mounting board side pads 101.

As shown in FIG. 7, the pair of mounting board side pads 103 are provided such that the first region 103a corresponding to the first region 101a has an overlapping portion 103aa that overlaps with the body substrate 21. The solder is formed on the mounting board side pad 103 in a location other than the overlapping portion 103aa. The flux contained in the solder melts before the alloy. Therefore, when the solder formed on the mounting board side pad 103 melts in the reflow process, the flux penetrates into the overlapping portion 103aa. As a result, the optical element package 20 is in close contact at the overlapping portion 103aa, so that the phenomenon of the optical element package 20 standing up can be more effectively suppressed.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. The technical scope of the present invention also includes embodiments obtained by appropriately combining the technical means disclosed in different embodiments.

1 Optical element module 10 Mounting substrate 11 Mounting substrate side pad (pad formed on the mounting substrate)
20 Optical element package 21 Body substrate 21a First surface 21b Second surface 21c Third surface 21d Fourth surface 21e Fifth surface 22 Optical element 24 First electrode (electrode on the first surface)
25 Second electrode (electrode on second surface)
25a Electrode pad (pad for electrode on second surface)
30 Soldering section

Claims (4)

A mounting board;
a side-view type optical element package mounted on the mounting substrate, the optical element package comprising: an optical element; and a body substrate including a first surface coupled to the optical element, a second surface parallel to the first surface, and a third surface perpendicular to the first surface and the second surface and facing the mounting substrate, the body substrate having electrodes on the first surface and the second surface;
a solder portion connecting a pad of the electrode on the second surface and a pad formed on the mounting substrate,
Let H be the height of the body substrate from the third surface, and h be the height of the pads of the electrodes on the second surface from the third surface, and h≦1/2·H.
the body substrate includes a fourth surface and a fifth surface that are perpendicular to the first surface, the second surface, and the third surface and parallel to each other;
the pad formed on the mounting substrate has a first region formed along a side of the second surface on the third surface side, and a second region connected to the first region and formed along a side of the fourth surface or the fifth surface on the third surface side,
an optical element module , wherein the pad formed on the mounting substrate is provided such that there is a gap between the second region and an edge of the fourth surface or the fifth surface on the third surface side ; The optical element module according to claim 1 , wherein the first region has an overlapping portion that overlaps with the body substrate in a plan view. The optical element module according to claim 1 , wherein the pad formed on the mounting substrate is L-shaped in a plan view. A manufacturing method for an optical element module in which a side-view type optical element package is mounted on a mounting substrate, comprising the steps of:
the optical element package includes an optical element, and a body substrate including a first surface coupled to the optical element, a second surface parallel to the first surface , a third surface perpendicular to the first and second surfaces and facing the mounting substrate , and fourth and fifth surfaces perpendicular to the first, second, and third surfaces and parallel to each other , the body substrate having electrodes on the first and second surfaces, wherein the height of the body substrate from the third surface is H and the height of the pad of the electrode on the second surface from the third surface is h, the body substrate includes a pad of the electrode on the second surface so that h≦1/2·H;
a step of forming a pad on the mounting board to be connected to a pad of an electrode on the second surface, the pad having a first region formed along an edge of the second surface on the third surface side, and a second region connected to the first region and formed along an edge of the fourth surface or the fifth surface on the third surface side, the pad being formed such that there is a gap between the edge of the fourth surface or the fifth surface on the third surface side and the second region;
forming solder on the pads of the mounting substrate;
a step of arranging the optical element package such that pads of electrodes on a second surface are aligned with pads of the mounting substrate in a plan view;
and melting the solder by heat treatment to connect the pads of the electrodes on the second surface and the pads of the mounting substrate with the solder.

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