JP2009099855A - Electric circuit and capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily connect a bypass capacitor, an external transmission line, and a ground potential by a wire. <P>SOLUTION: An electric circuit includes a capacitor, and includes a circuit board, a dielectric with its lower surface opposed to the circuit board, a first counter electrode formed on an upper surface of a dielectric, a second counter electrode formed on the lower surface of the dielectric, a surface electrode formed on the upper surface of the dielectric, and a connection portion electrically connecting the second counter electrode to the surface electrode. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric circuit and a capacitor. The present invention particularly relates to a bypass capacitor provided between a transmission path and a ground potential in an electric circuit, and an electric circuit including the bypass capacitor.

A bypass capacitor is used for the purpose of suppressing transmission / radiation noise from the printed circuit board to an electronic component such as an IC mounted on the printed circuit board. As such a bypass capacitor, a single plate capacitor in which a dielectric layer and an electrode layer sandwiching the dielectric layer are stacked on a printed circuit board is known (see, for example, Patent Document 1). In addition, a capacitor in which electrodes are provided on the upper and lower surfaces of a dielectric layer and bonded to a printed board may be used as a bypass capacitor.
International Publication No. 99/052337 Pamphlet

  When such a capacitor is used as a bypass capacitor, both the electrodes provided on the upper surface and the lower surface of the dielectric layer in the capacitor must be connected to the wiring pattern of the printed board by wire bonding or the like. In addition, when the capacitor is arranged in the very vicinity of other components on the printed circuit board, it is difficult to connect the electrode provided on the lower surface and the wiring pattern through the gap between the component or the like and the capacitor by wire bonding. is there.

  In order to solve the above-described problems, in a first embodiment of the present invention, an electric circuit including a capacitor, a circuit board, a dielectric provided with a lower surface facing the circuit board, and an upper surface of the dielectric A first counter electrode formed, a second counter electrode formed on the lower surface of the dielectric, a surface electrode formed on the upper surface of the dielectric, and a connection portion for electrically connecting the second counter electrode and the surface electrode An electrical circuit is provided.

  According to a second aspect of the present invention, there is provided a capacitor formed on the circuit board, the dielectric having a lower surface facing the circuit board, and a first counter electrode formed on the upper surface of the dielectric. A capacitor is provided that includes a second counter electrode formed on the lower surface of the dielectric, a surface electrode formed on the upper surface of the dielectric, and a connection portion that electrically connects the second counter electrode and the surface electrode. .

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 shows a top view of a portion of an electrical circuit 10. FIG. 2 is a side view of the part of the electric circuit 10 as viewed from the direction “A” shown in FIG. As shown in FIGS. 1 and 2, the electric circuit 10 includes a circuit board 20, an insulating layer 30 formed on a part of the upper surface of the circuit board 20, and a wiring 40 patterned on the upper surface of the insulating layer 30. 50. In the electric circuit 10, the wiring 40 is a transmission path, and the wiring 50 is a ground potential.

  The electric circuit 10 further includes a capacitor 100 formed at a position different from the insulating layer 30 on the upper surface of the circuit board 20. The capacitor 100 includes a first counter electrode 110, a second counter electrode 120, and a dielectric layer 130. The dielectric layer 130 may have a substantially rectangular thin plate shape, and one surface (hereinafter referred to as “lower surface”) is provided to face the circuit board 20. The first counter electrode 110 is formed on a surface opposite to the lower surface of the dielectric layer 130 (hereinafter referred to as “upper surface”). The second counter electrode 120 is formed between the lower surface of the dielectric layer 130 and the upper surface of the circuit board 20.

  The capacitor 100 may be formed by sequentially stacking the second counter electrode 120, the dielectric layer 130, and the first counter electrode 110 on the upper surface of the circuit board 20. The second counter electrode 120 is preferably formed at least partially along the edge of the lower surface of the dielectric layer 130. In this example, the side facing the insulating layer 30 on the lower surface of the dielectric layer 130 is used. Is formed along. As another example, the second counter electrode 120 may be formed along all sides on the lower surface of the dielectric layer 130.

  Capacitor 100 further includes a surface electrode 140 formed on the upper surface of dielectric layer 130 and a connecting portion 150 that electrically connects second counter electrode 120 and surface electrode 140. The surface electrodes 140 are formed on the upper surface of the dielectric layer 130 so as to be separated from the first counter electrode 110 and are electrically insulated from each other. The connection part 150 is formed on a side surface (including the side) extending from the side where the second counter electrode 120 is formed in the dielectric layer 130 and is electrically connected to the second counter electrode 120. The connecting portion 150 may be formed on at least a part of the side surface of the dielectric layer 130 or may be formed on the entire side surface.

  Part of the surface electrode 140 is preferably formed along the edge of the upper surface of the dielectric layer 130. In this example, the surface electrode 140 corresponds to the side surface on which the connection portion 150 is formed on the upper surface of the dielectric layer 130. It is formed along a side that intersects (intersects with the side surface). Therefore, the surface electrode 140 is electrically connected to the connection part 150 and is also electrically connected to the second counter electrode 120 via the connection part 150.

  The first counter electrode 110 is connected to the wiring 40 through the wire 60, and the surface electrode 140 is connected to the wiring 50 through the wire 70. The wires 60 and 70 may be bonding wires that electrically connect electrodes or wirings connected to both ends by aerial wiring, and the wires 60 and 70 may be connected as described above by wire bonding. preferable.

  By connecting the wires 60 and 70 in this way, the first counter electrode 110 is electrically connected to the wiring 40 which is a transmission path, and is electrically connected to the surface electrode 140 via the connection portion 150. The two counter electrodes 120 are electrically connected to the wiring 50 that is at the ground potential. Thereby, in the electric circuit 10, the capacitor 100 functions as a bypass capacitor provided between the wiring 40 that is a transmission path and the wiring 50 that is a ground potential.

  Here, in the electric circuit 10 of the present embodiment, the distance between the insulating layer 30 and the capacitor 100 is, for example, 0.1 mm, whereas the height of the insulating layer 30 and the capacitor 100 is, for example, 0.3 mm. Yes, the height is larger than the interval. Therefore, by connecting the wire 70 to the surface electrode 140, the wire 70 is passed through the narrow gap as compared with the case where the wire 70 is directly connected to the second counter electrode 120 formed on the lower surface of the dielectric layer 130. The wire 70 can be easily connected to the second counter electrode 120 without being connected to the second counter electrode 120.

  Further, when the electric circuit 10 is manufactured by bonding the capacitor 100 to the upper surface of the circuit board 20, the adhesive may protrude between the insulating layer 30 and the capacitor 100 on the upper surface of the circuit board 20. . However, in the electric circuit 10 of the present embodiment, the wire 70 can be connected to the surface electrode 140 regardless of the presence or absence of the protruding adhesive, so that the connection between the wire 70 and the second counter electrode 120 can be more reliably performed. Can be implemented.

  Further, the length of the necessary wire 70 can be shortened as compared with the case where the second counter electrode 120 formed on the lower surface of the dielectric layer 130 is directly connected. The resistance value per unit length in the transmission direction of the connecting portion 150 is preferably smaller than the resistance value per unit length in the transmission direction of the wire 70. Thereby, compared with connecting the wire 70 to the 2nd counter electrode 120 directly, the 2nd counter electrode 120 can be made into a grounding potential with a sufficient precision. That is, the length of the wire 70 having a constant resistance value per unit length is shortened, and the resistance value per unit length of the connection portion 150 connecting the surface electrode 140 and the second counter electrode 120 is the wire. By being smaller than 70, the potential difference generated between the second counter electrode 120 and the wiring 50 due to the influence of the resistance value of the wire 70 can be further reduced.

  In the electric circuit 10, the first counter electrode 110 may be connected to the wiring 50 through the wire 60, and the surface electrode 140 may be connected to the wiring 40 through the wire 70. In this case, the resistance value per unit length in the transmission direction of the connecting portion 150 is preferably smaller than the resistance value per unit length in the transmission direction of the wire 60.

  As described above, the electric circuit 10 includes the surface electrode 140 that is formed along the edge of the upper surface of the dielectric layer 130 and is electrically connected to the second counter electrode 120 through the connection portion 150. Accordingly, the wire 70 and the second counter electrode 120 are not directly connected to the second counter electrode 120 but connected to the surface electrode 140 connected to the second counter electrode 120 via the connection portion 150. Can be easily connected by wire bonding.

  FIG. 3 shows a top view of a part of the electric circuit 11. 4 shows a side view of the part of the electric circuit 11 as seen from the direction of “B” shown in FIG. In the electric circuit 11, about the same structure as the said electric circuit 10, the same code | symbol as the said structure of the said electric circuit 10 is attached | subjected to FIG. 3 and FIG. 4, and description is abbreviate | omitted. As shown in FIGS. 3 and 4, the electric circuit 11 includes a circuit board 21, a plurality of insulating layers 30 formed on the upper surface of the circuit board 21, and wiring 40 patterned on the upper surface of each insulating layer 30. 50. In the electric circuit 11, each wiring 40 is a transmission path, and each wiring 50 is a ground potential.

  The electric circuit 11 further includes a plurality of capacitors 101 formed at positions different from the plurality of insulating layers 30 on the upper surface of the circuit board 21. The plurality of capacitors 101 are provided with a substantially rectangular dielectric whose one side surface (hereinafter referred to as “lower surface”) faces the circuit board 21 and faces the plurality of insulating layers 30 on one side in the longitudinal direction on the upper surface. Share layer 131. Each of the plurality of capacitors 101 includes a second counter electrode 120 formed between the lower surface of the dielectric layer 131 and the upper surface of the circuit board 21, and a surface opposite to the lower surface of the dielectric layer 131 (hereinafter, 1) each having a pair of first counter electrodes 110 arranged substantially parallel to the one side of the upper surface of the dielectric layer 131.

  In each of the capacitors 101, the first counter electrode 110 and the second counter electrode 120 are preferably formed to face each other with the dielectric layer 131 interposed therebetween. Further, in this example, each of the plurality of capacitors 101 has the second counter electrode 120 separately, but is not limited to such a form. For example, the plurality of capacitors 101 may share the second counter electrode 120 formed on the entire lower surface of the dielectric layer 131.

  Each of the plurality of capacitors 101 further includes a surface electrode 141 formed on the upper surface of the dielectric layer 131, and a connection portion 151 that electrically connects the second counter electrode 120 and the surface electrode 141. In this example, the surface electrode 141 is integrally formed along the one side of the upper surface of the dielectric layer 131, and the connection portion 151 is integrally formed on the side surface of the dielectric layer 131 including the one side. Therefore, each of the plurality of capacitors 101 shares the surface electrode 141 and the connection portion 151. As another example, each of the capacitors 101 may have the surface electrode 141 and the connection portion 151 separately.

  Each of the plurality of first counter electrodes 110 is connected to the wiring 40 via the wire 60. Further, the surface electrode 141 is connected to the wiring 50 through a plurality of wires 70 having one ends connected to the facing region 161 at a position facing each of the plurality of first counter electrodes 110. By connecting the wires 60 and 70 in this way, each of the plurality of first counter electrodes 110 is electrically connected to the wiring 40 that is a transmission path, and is electrically connected via the surface electrode 141 and the connection portion 151. The second counter electrode 120 connected to is electrically connected to the wiring 50 having the ground potential. Thereby, in the electric circuit 11, each of the plurality of capacitors 101 functions as a bypass capacitor provided between the corresponding wiring 40 that is a transmission path and the wiring 50 that is a ground potential.

  In the electric circuit 11, the surface electrode 141 has a width in a direction orthogonal to the one side of the upper surface of the dielectric layer 131 in the portion other than the facing region 161 than in the facing region 161. Thereby, it is possible to reduce a capacitance component generated between a portion of the surface electrode 141 other than the counter region 161 and the plurality of first counter electrodes 110.

  In place of the electric circuits 10 and 11 of the present embodiment, the capacitors 100 and 101 may be arranged on the bottom surfaces of the depressions provided on the upper surfaces of the circuit boards 20 and 21. In this case, the first counter electrode 110 and the second counter electrode 120 of the capacitors 100 and 101 are connected to the wirings 40 and 50 formed on the upper surfaces of the circuit boards 20 and 21 via the wires 60 and 70, respectively. Also good. In place of this, the first counter electrode 110 and the second counter electrode 120 of the capacitors 100, 101 are replaced with pads and wires provided on components such as IC, LSI, or SiP mounted on the circuit boards 20, 21. 60 and 70 may be connected to each other.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

A top view of a portion of the electrical circuit 10 is shown. The side view which looked at a part of electric circuit 10 from the direction of "A" shown in FIG. 1 is shown. A top view of a portion of the electrical circuit 11 is shown. The side view which looked at a part of electric circuit 11 from the direction of "B" shown in FIG. 1 is shown.

Explanation of symbols

10, 11 Electrical circuit 20, 21 Circuit board 30 Insulating layer 40, 50 Wiring 60, 70 Wire 100, 101 Capacitor 110 First counter electrode 120 Second counter electrode 130, 131 Dielectric layer 140, 141 Surface electrode 150, 151 Connection Part 161 opposite region

Claims (8)

An electrical circuit including a capacitor,
A circuit board;
A dielectric provided with a lower surface facing the circuit board;
A first counter electrode formed on the top surface of the dielectric;
A second counter electrode formed on the lower surface of the dielectric;
A surface electrode formed on the upper surface of the dielectric;
An electrical circuit comprising: a connection portion that electrically connects the second counter electrode and the surface electrode. The second counter electrode is formed along a predetermined side of the lower surface of the dielectric,
The connecting portion is formed on a side surface of the dielectric extending from the predetermined side,
The electric circuit according to claim 1, wherein the surface electrode is formed along a predetermined side of the upper surface of the dielectric corresponding to a side surface of the dielectric on which the connection portion is formed. The capacitor is a bypass capacitor provided between a transmission path in the electric circuit and a ground potential;
The first counter electrode is connected to the transmission path;
The electric circuit according to claim 1, wherein the surface electrode is connected to the ground potential. The electric circuit according to claim 3, further comprising a wire that connects the surface electrode and the ground potential with an air wiring. The electric circuit according to claim 4, wherein a resistance value per unit length in the transmission direction of the connection portion is smaller than a resistance value per unit length in the transmission direction of the wire. A plurality of the first counter electrodes arranged substantially parallel to one side of the upper surface of the dielectric on which the surface electrode is formed;
The electric circuit according to claim 2, wherein the surface electrode includes a plurality of opposing regions at positions facing the plurality of first opposing electrodes, and is integrally formed along the side of the upper surface of the dielectric. The surface electrode is formed so that a width of a region other than the opposing region in a direction orthogonal to the one side of the upper surface of the dielectric is smaller than a maximum width in the direction of the opposing region. Electrical circuit as described in. A capacitor formed on a circuit board,
A dielectric provided with a lower surface facing the circuit board;
A first counter electrode formed on the top surface of the dielectric;
A second counter electrode formed on the lower surface of the dielectric;
A surface electrode formed on the upper surface of the dielectric;
A capacitor comprising: a connection portion that electrically connects the second counter electrode and the surface electrode.

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