Circuit module

Abstract

To provide a circuit module capable of reducing the length of the bonding wires that electrically connect the integrated circuit to the substrate.SOLUTION: A circuit module 1 includes a substrate 2, a heat sink 4, and an integrated circuit 5. The substrate 2 has a mounting surface 21 and a mounting surface 22 facing in the thickness direction, and a through hole 3. The heat sink 4 is attached to the mounting surface 22. The integrated circuit 5 is attached by adhesive 6 to the attachment portion 42 of the heat sink 4, which faces the through hole 3 in the thickness direction. The substrate 2 includes an electrode 23 formed on the mounting surface 21. The integrated circuit 5 is electrically connected to the electrode 23 via a bonding wire W1. The through-hole 3 has a first opening 3a formed in the mounting surface 21 and a second opening 3b formed in the mounting surface 22. The first opening 3a is smaller than the second opening 3b.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a circuit module. [Background technology]

[0002] In the hybrid integrated circuit of Patent Document 1, the IC chip is mounted on a heat sink by die bonding, and the substrate is attached to the heat sink with an adhesive. The IC chip and the surface pattern of the substrate are electrically connected by bonding wires. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-78919 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the bonding wires that electrically connect the IC chip (integrated circuit) and the substrate tend to be long, resulting in a large inductance of the bonding wires.

[0005] An object of the present disclosure is to provide a circuit module that can shorten the bonding wires that electrically connect an integrated circuit to a substrate. [Means for solving the problem]

[0006] A circuit module according to one aspect of the present disclosure includes a substrate, a heat sink, and an integrated circuit. The substrate has a mounting surface and an attachment surface that face each other in a thickness direction, and a through hole. The heat sink is attached to the attachment surface. The integrated circuit is attached with an adhesive to an attachment portion of the heat sink that faces the through hole in the thickness direction. The substrate includes electrodes formed on the mounting surface. The integrated circuit is electrically connected to the electrodes by bonding wires. The through hole has a first opening formed on the mounting surface and a second opening formed on the attachment surface. The first opening is smaller than the second opening. [Effects of the Invention]

[0007] The present disclosure has the effect of shortening the bonding wires that electrically connect the integrated circuit and the substrate. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a side cross-sectional view showing a circuit module according to an embodiment. [Figure 2] FIG. 2 is a plan view showing the circuit module of the same. [Figure 3] FIG. 3 is a side cross-sectional view showing a main part of the circuit module. [Figure 4] FIG. 4 is a side cross-sectional view showing a circuit module of a comparative example. [Figure 5] FIG. 5 is a side cross-sectional view showing a circuit module of the first modified example. [Figure 6] FIG. 6 is a plan view showing the main part of the same. [Figure 7] FIG. 7 is a side cross-sectional view showing a circuit module of the second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present disclosure relates generally to a circuit module, and more particularly to a circuit module that electrically connects an integrated circuit and a substrate by bonding wires.

[0010] Circuit modules according to embodiments will be described below with reference to the drawings. However, the following embodiment is merely one of various embodiments of the present disclosure. The following embodiment can be modified in various ways depending on the design, etc., as long as it can achieve the object of the present disclosure and does not deviate from the technical concept of the present disclosure. Furthermore, each diagram described in the following embodiments is a schematic diagram, and the ratios of the sizes and thicknesses of the components in the diagrams do not necessarily reflect the actual dimensional ratios.

[0011] (Embodiment) (1) Overview 1 and 2 show a circuit module 1 of this embodiment.

[0012] The circuit module 1 includes a substrate 2, a heat sink 4, and an integrated circuit 5. The substrate 2 has a mounting surface 21 and an attachment surface 22 that face each other in the thickness direction, and a through hole 3. The heat sink 4 is attached to the attachment surface 22. The integrated circuit 5 is attached with an adhesive 6 to an attachment portion 42 of the heat sink 4 that faces the through hole 3 in the thickness direction. The integrated circuit 5 is electrically connected to an electrode 23 formed on the mounting surface 21 by a bonding wire W1. The through hole 3 has a first opening 3a formed on the mounting surface 21 and a second opening 3b formed on the attachment surface 22. The first opening 3a is smaller than the second opening 3b.

[0013] In the circuit module 1 having the above-described configuration, the first opening 3a of the through-hole 3 is smaller than the second opening 3b. Therefore, the circuit module 1 can shorten the distance between the integrated circuit 5 and the periphery of the first opening 3a while ensuring space for the adhesive 6 to flow out (adhesive pool) at the attachment site 42. As a result, the circuit module 1 can shorten the bonding wire W1 that electrically connects the integrated circuit 5 and the substrate 2.

[0014] (2) Details The circuit module 1 shown in FIGS. 1 and 2 includes a substrate 2, a heat sink 4, and an integrated circuit 5.

[0015] In the following description, the direction in which the substrate 2 and heat sink 4 are aligned in Fig. 1 is defined as the up-down direction, the side of the substrate 2 viewed from the heat sink 4 is defined as the top, and the side of the heat sink 4 viewed from the substrate 2 is defined as the bottom. Also, the direction along the long sides of the substrate 2 in Fig. 2 is defined as the left-right direction, and the direction along the short sides of the substrate 2 is defined as the front-rear direction. However, these definitions are intended to make the circuit module 1 easier to understand and are not intended to define the direction in which the circuit module 1 is used.

[0016] (2.1) Substrate The substrate 2 is a rectangular plate having a pair of long sides and a pair of short sides, and includes a mounting surface 21 and an attachment surface 22 that face each other in the thickness direction. In FIG. 1, the thickness direction corresponds to the up-down direction. In FIG. 1, the mounting surface 21 corresponds to the upper surface, and the attachment surface 22 corresponds to the lower surface. The mounting surface 21 and the attachment surface 22 are each rectangular. However, the substrate 2 may be shaped other than a rectangular plate, and may be, for example, a circular plate, an elliptical plate, or a polygonal plate.

[0017] Electrical components G1 such as resistors, capacitors, coils, IC (Integrated Circuit) chips, and connectors are mounted on the mounting surface 21. A pattern portion 24 is also formed on the mounting surface 21. The pattern portion 24 forms an electrical path including conductors that electrically connect the electrical components G1 mounted on the mounting surface 21. Furthermore, an electrode 23 electrically connected to the pattern portion 24 is formed on the mounting surface 21. The electrode 23 is electrically connected to the electrical component G1 or the pattern portion 24. In the example of FIG. 1, the electrode 23 is electrically connected to the pattern portion 24. The electrode 23 is also connected to a bonding wire W1. The electrode 23 and the pattern portion 24 are formed of a conductive metal such as copper.

[0018] The mounting surface 22 does not have the pattern portion 24 or the electrode 23 formed thereon, and functions as a surface for mounting the heat sink 4 .

[0019] The substrate 2 has a through-hole 3 formed therein, which penetrates the substrate 2 in the thickness direction (vertical direction). The through-hole 3 will be described in detail later.

[0020] (2.2) Heat sink The heat sink 4 is made of a metal such as aluminum or copper. The top surface 41 of the heat sink 4 is a rectangular flat surface. The top surface 41 of the heat sink 4 faces the mounting surface 22 of the substrate 2 and is attached to the mounting surface 22 of the substrate 2 by an adhesive 7. In other words, the adhesive 7 is sandwiched between the mounting surface 22 and the top surface 41, physically connecting the substrate 2 and the heat sink 4.

[0021] A through hole 3 is formed in the substrate 2, and if a portion of the upper surface 41 that fits into the through hole 3 in the thickness direction of the substrate 2 (opposing the second opening 3b of the through hole 3) is defined as an attachment portion 42, no adhesive 7 is applied to the attachment portion 42, and the upper surface 41 of the heat sink 4 is exposed at the attachment portion 42. The attachment portion 42 forms the bottom surface of the through hole 3.

[0022] The integrated circuit 5 is attached to the attachment portion 42 with an adhesive 6. The heat sink 4 has a function of dissipating heat generated by the integrated circuit 5. The heat generated by the integrated circuit 5 is transferred to the heat sink 4, for example, via the adhesive 6, and dissipated from the heat sink 4. The heat generated by the integrated circuit 5 is also transferred to the heat sink 4, for example, via the bonding wires W1, the substrate 2, and the adhesive 7, and dissipated from the heat sink 4. The heat sink 4 preferably has a plurality of fins.

[0023] By mounting the heat sink 4 on the attachment surface 22 of the substrate 2, it is possible to increase the contact area between the heat sink 4 and the substrate 2. As a result, the circuit module 1 can improve the heat dissipation efficiency of the integrated circuit 5.

[0024] (2.3) Integrated Circuits The integrated circuit 5 is an IC (Integrated Circuit) chip in which an integrated circuit is formed on a substrate. The integrated circuit 5 has an end face 51 corresponding to the upper face and an adhesive face 52 corresponding to the lower face as upper and lower faces that face each other in the vertical direction. The end face 51 and the adhesive face 52 are each rectangular. The integrated circuit 5 is mounted on the attachment portion 42 of the upper face 41 of the heat sink 4 so that the adhesive face 52 faces the upper face 41. However, the integrated circuit 5 may have a shape other than a rectangular plate, and may be, for example, a circular plate, an elliptical plate, or a polygonal plate.

[0025] The integrated circuit 5 is attached to the attachment portion 42 on the upper surface 41 of the heat sink 4 by die bonding using an adhesive 6. That is, the adhesive 6 is sandwiched between the attachment surface 52 of the integrated circuit 5 and the attachment portion 42, physically connecting the integrated circuit 5 and the heat sink 4. The adhesive 6 used for die bonding is lead, resin (which may contain a metal filler), solder, or the like.

[0026] The integrated circuit 5 is an IC that performs high-speed signal processing or an IC that processes a large number of signals, and therefore consumes relatively large amounts of power and generates relatively large amounts of heat. The heat generated by the integrated circuit 5 is transferred to the heat sink 4, for example, via the adhesive 6, and is dissipated from the heat sink 4. The heat generated by the integrated circuit 5 is also transferred to the heat sink 4, for example, via the bonding wires W1, the substrate 2, and the adhesive 7, and is dissipated from the heat sink 4.

[0027] The integrated circuit 5 attached to the attachment portion 42 is fitted in the through-hole 3 of the substrate 2. The integrated circuit 5 is electrically connected to electrodes 23 formed on the mounting surface 21 of the substrate 2 by bonding wires W1. The bonding wires W1 are thin wires made of metal such as gold, silver, copper, or aluminum. Specifically, a plurality of electrodes 53 are provided on the left and right sides of the end surface 51 of the integrated circuit 5. First ends of the bonding wires W1 are connected to the electrodes 53 of the integrated circuit 5, and second ends of the bonding wires W1 are connected to the electrodes 23 of the substrate 2. The integrated circuit 5 receives driving power and signals from the substrate 2 via the bonding wires W1. The integrated circuit 5 transmits signals to the substrate 2 via the bonding wires W1.

[0028] (2.4) Through holes FIG. 3 is an enlarged view of the through-hole 3. As shown in FIG.

[0029] The through hole 3 has a first opening 3a formed in the mounting surface 21 of the substrate 2 and a second opening 3b formed in the attachment surface 22 of the substrate 2. The first opening 3a is smaller than the second opening 3b. The first opening 3a and the second opening 3b are larger than the integrated circuit 5 (in terms of length in the left-right direction and length in the front-rear direction).

[0030] Specifically, the through hole 3 is a through hole with a rectangular cross section (see FIG. 2). The through hole 3 is formed between the mounting surface 21 and the attachment surface 22. The upper end of the through hole 3 is a rectangular first opening 3a formed in the mounting surface 21. The lower end of the through hole 3 is a rectangular second opening 3b formed in the attachment surface 22. The length in the front-to-rear direction of the first opening 3a is equal to the length in the front-to-rear direction of the second opening 3b. The length in the left-to-right direction of the first opening 3a is shorter than the length in the left-to-right direction of the second opening 3b.

[0031] The first opening 3a has a left side 3c and a right side 3d (see FIG. 2) extending in the front-rear direction. The left side 3c and the right side 3d face each other in the left-right direction. On the mounting surface 21 of the substrate 2, three electrodes 23 are arranged side by side along the left side 3c, and three electrodes 23 are arranged side by side along the right side 3d. At least a portion of each electrode 23 is located inside the second opening 3b in a plan view in the thickness direction. In this case, a portion of each electrode 23 may be located inside the second opening 3b in a plan view in the thickness direction, or the entirety of each electrode 23 may be located inside the second opening 3b in a plan view in the thickness direction. In FIG. 2, a portion of each electrode 23 is located inside the second opening 3b in a plan view in the thickness direction.

[0032] At the bottom of the through hole 3, the integrated circuit 5 is attached to the attachment portion 42 of the heat sink 4 with an adhesive 6. An end face 51 of the integrated circuit 5 is located inside the first opening 3a of the through hole 3 in a plan view in the thickness direction of the substrate 2.

[0033] The inner surface of through hole 3 has a step portion 32 formed on left inner surface 31 extending downward from left side 3c. Step portion 32 has a single-step shape and is formed so that the lower part of left inner surface 31 is located to the left of the upper part of left inner surface 31. Specifically, step portion 32 has a rectangular upper step surface 321 extending downward from left side 3c, a rectangular connecting surface 322 extending leftward from the lower end of upper step surface 321, and a rectangular lower step surface 323 extending downward from the left end of connecting surface 322. The lower end of lower step surface 323 corresponds to left side 3e of second opening 3b.

[0034] Furthermore, the inner surface of the through hole 3 has a step portion 34 formed on the right inner surface 33 that is formed downward from the right side 3d. The step portion 34 has a one-step staircase shape, and is formed so that the lower part of the right inner surface 33 is located further to the right than the upper part of the right inner surface 33. Specifically, the step portion 34 has a rectangular upper step surface 341 extending downward from the right side 3d, a rectangular connecting surface 342 extending rightward from the lower end of the upper step surface 341, and a rectangular lower step surface 343 extending downward from the right end of the connecting surface 342. The lower end of the lower step surface 343 corresponds to the right side 3f of the second opening 3b.

[0035] A dimension L1 between the upper surface 321 and the upper surface 341 in the left-right direction is smaller than a dimension L2 between the lower surface 323 and the lower surface 343 in the left-right direction.

[0036] That is, the through hole 3 has step portions 32, 34 formed on the inner surface of the through hole 3 at least partially in the circumferential direction of the inner surface. The step portions 32, 34 make the cross-sectional area of the through hole 3 on the side of the first opening 3a smaller than the cross-sectional area of the through hole 3 on the side of the second opening 3b in the thickness direction (vertical direction) of the substrate 2. The step portions 32, 34 are formed on the inner surface of the through hole 3 partially in the circumferential direction.

[0037] Here, the adhesive 6 used to attach the integrated circuit 5 to the attachment portion 42 of the heat sink 4 spills out from the adhesive surface 52 of the integrated circuit 5 and flows out onto the periphery of the lower end of the integrated circuit 5. In the circuit module 1, the size (length in the left-right direction, length in the front-back direction) of the second opening 3b is made larger than the size (length in the left-right direction, length in the front-back direction) of the integrated circuit 5, taking into account the amount of the flowing out adhesive 6. As a result, the adhesive 6 flowing out onto the periphery of the lower end of the integrated circuit 5 is prevented from coming into contact with the vicinity of the lower end of the through hole 3.

[0038] On the other hand, on the left inner surface 31 of the through hole 3, the step portion 32 causes the upper surface 321 to protrude more inward than the lower surface 323, and in the left-right direction, the left side 3c of the first opening 3a is closer to the left side of the end face 51 of the integrated circuit 5. Therefore, the length of the bonding wire W1 that electrically connects the electrode 23 along the left side 3c of the first opening 3a and the electrode 53 on the left side of the integrated circuit 5 can be shortened.

[0039] Furthermore, on the right inner surface 33 of the through hole 3, the step portion 34 causes the upper surface 341 to protrude more inward than the lower surface 343, and in the left-right direction, the right side 3d of the first opening 3a is closer to the right side of the end face 51 of the integrated circuit 5. Therefore, the length of the bonding wire W1 that electrically connects the electrode 23 along the right side 3d of the first opening 3a to the electrode 53 on the right side of the integrated circuit 5 can be shortened.

[0040] FIG. 4 shows a circuit module 100 of a comparative example.

[0041] The circuit module 100 has a through hole 300 instead of the through hole 3 in the configuration of the circuit module 1. The through hole 300 is a through hole with a rectangular cross section. The upper end of the through hole 300 is a rectangular first opening 300a formed in the mounting surface 21. The lower end of the through hole 300 is a rectangular second opening 300b formed in the attachment surface 22. The size (length in the left-right direction and length in the front-to-rear direction) of the first opening 300a is the same as the size (length in the left-to-right direction and length in the front-to-rear direction) of the second opening 300b. The first opening 300a has a left side 300c and a right side 300d extending in the front-to-rear direction.

[0042] The left side 300c of the through hole 300 in this comparative example is farther from the end face 51 of the integrated circuit 5 than the left side 3c of the above-described through hole 3. Therefore, the bonding wire W100 that electrically connects the electrode 23 along the left side 300c of the first opening 300a and the electrode 53 on the left side of the integrated circuit 5 is longer than the above-described bonding wire W1.

[0043] In this comparative example, the right side 300d of the through hole 300 is farther from the end face 51 of the integrated circuit 5 than the right side 3d of the above-described through hole 3. Therefore, the bonding wire W100 electrically connecting the electrode 23 along the right side 300d of the first opening 300a and the electrode 53 on the right side of the integrated circuit 5 is longer than the above-described bonding wire W1.

[0044] That is, the bonding wire W1 of the circuit module 1 is shorter than the bonding wire W100 of the comparative example. Therefore, the inductance component of the bonding wire W1 is smaller than the inductance component of the bonding wire W100. As a result, the frequency band of the signal transmitted through the bonding wire W1 is wider than the frequency band of the signal transmitted through the bonding wire W100, improving the signal quality (signal waveform).

[0045] Furthermore, a configuration for making the first opening 3a smaller than the second opening 3b can be easily realized by using the step portions 32 and 34. The step portions 32 and 34 in the through hole 3 can be formed relatively easily.

[0046] (3) First Modification FIG. 5 shows a circuit module 1A of a first modified example.

[0047] The circuit module 1A includes a protrusion 43 having an attachment site 42 on its tip surface. As shown in Fig. 6, the protrusion 43 is located inside the second opening 3b when viewed from above in the thickness direction of the substrate 2. The protrusion 43 has a rectangular shape, and the upper surface of the protrusion 43 is the attachment site 42, to which the integrated circuit 5 is attached with adhesive 6.

[0048] The integrated circuit 5 has an adhesive surface 52 attached to the heat sink 4 with the adhesive 6, and an end surface 51 facing the adhesive surface 52. In the thickness direction of the substrate 2, the end surface 51 of the integrated circuit 5 is located between the mounting surface 21 and the attachment surface 22 of the substrate 2. In the thickness direction of the substrate 2, the end surface 51 of the integrated circuit 5 is preferably flush with the mounting surface 21 of the substrate 2.

[0049] In this case, end face 51 (see FIG. 5) of integrated circuit 5 in circuit module 1A is located higher than end face 51 (see FIG. 3) of integrated circuit 5 in circuit module 1. In the vertical direction, dimension Lc (see FIG. 5) between end face 51 of integrated circuit 5 in circuit module 1A and the upper end of bonding wire W1A is smaller than dimension Ld (see FIG. 3) between end face 51 of integrated circuit 5 in circuit module 1 and the upper end of bonding wire W1. In other words, bonding wire W1A in circuit module 1A is shorter than bonding wire W1 in circuit module 1.

[0050] As a result, the frequency band of the signal transmitted through the bonding wire W1A of the circuit module 1A is wider than the frequency band of the signal transmitted through the bonding wire W1 of the circuit module 1, improving the signal quality (signal waveform).

[0051] (4) Second Modification 7 shows a circuit module 1B according to a second modification example, which is configured as the circuit module 1, but with a through-hole 3B instead of the through-hole 3.

[0052] Through hole 3B has tapered surface 36 formed on the lower part of left inner surface 35 extending downward from left side 3c of through hole 3B. Tapered surface 36 is an inclined surface that slopes leftward as it extends downward, and the lower end of tapered surface 36 forms left side 3e of second opening 3b.

[0053] Through hole 3B has tapered surface 38 formed on the lower part of right inner surface 37 extending downward from right side 3d of through hole 3B. Tapered surface 38 is an inclined surface that slopes to the right as it extends downward, and the lower end of tapered surface 38 forms right side 3f of second opening 3b.

[0054] The dimension L3 in the left-right direction between the tapered surface 36 and the tapered surface 38 gradually increases downward.

[0055] That is, through hole 3B has tapered surfaces 36, 38 formed on at least a portion of the circumferential direction of the inner surface of through hole 3B. Tapered surfaces 36, 38 make the cross-sectional area of through hole 3B on the side of first opening 3a smaller than the cross-sectional area of through hole 3B on the side of second opening 3b in the thickness direction of substrate 2.

[0056] In this modification, the size (left-right length, front-rear length) of second opening 3b is also made larger than the size (left-right length, front-rear length) of integrated circuit 5, taking into consideration the amount of adhesive 6 that will flow out. As a result, adhesive 6 that has flowed out to the periphery of the lower end of integrated circuit 5 is prevented from coming into contact with the periphery of second opening 3b.

[0057] On the other hand, on the left inner surface 35 of the through hole 3, the tapered surface 36 brings the left side 3c of the through hole 3 closer to the left side of the end face 51 of the integrated circuit 5. Therefore, the length of the bonding wire W1 that electrically connects the electrode 23 along the left side 3c of the first opening 3a and the electrode 53 on the left side of the integrated circuit 5 can be shortened.

[0058] Furthermore, on the right inner surface 37 of the through hole 3, the tapered surface 38 brings the right side 3d of the through hole 3 closer to the right side of the end face 51 of the integrated circuit 5. Therefore, the length of the bonding wire W1 that electrically connects the electrode 23 along the right side 3d of the first opening 3a and the electrode 53 on the right side of the integrated circuit 5 can be shortened.

[0059] Furthermore, the substrate thickness Le (see FIG. 7) directly below the electrode 23 in the circuit module 1B is thicker than the substrate thickness Lf (see FIG. 3) directly below the electrode 23 in the circuit module 1. Therefore, in the circuit module 1B, the load caused by the ultrasonic waves applied to the electrode 23 during wire bonding is less likely to escape, improving the reliability of the wire bonding.

[0060] Therefore, as shown in FIG. 7, each electrode 23 can be positioned close to the periphery of the first opening 3a of the through hole 3B, further shortening the length of the bonding wire W1. That is, at least a portion of each electrode 23 is located inside the second opening 3b in a planar view in the thickness direction. In this case, a portion of each electrode 23 may be located inside the second opening 3b in a planar view in the thickness direction, or the entire electrode 23 may be located inside the second opening 3b in a planar view in the thickness direction. In FIG. 7, a portion of each electrode 23 is located inside the second opening 3b in a planar view in the thickness direction.

[0061] Furthermore, tapered surfaces 36, 38 in through hole 3 create a space within through hole 3 for the adhesive 6 to flow out. In this case, since the shape of adhesive 6 is a fillet, tapered surfaces 36, 38 can be shaped to follow the fillet of adhesive 6. As a result, the area of the inner surface of through hole 3 that is cut away for tapered surfaces 36, 38 can be reduced, thereby improving the rigidity of substrate 2.

[0062] (5) Third Modification In the above-described embodiment and first modification, the step portion may be formed around the entire circumferential circumference on the inner surface of the through-hole 3. In this case, the electrode 23 can be disposed around the entire circumference of the first opening 3a.

[0063] In the above-described embodiment and first modification, a step portion having multiple steps may be provided.

[0064] In the second modified example described above, the tapered surface may be formed around the entire circumferential circumference of the inner surface of the through-hole 3. In this case, the electrode 23 can be disposed around the entire circumference of the first opening 3a.

[0065] The configurations described in the above-described embodiment and modifications can be combined as appropriate.

[0066] (6) Summary A circuit module (1, 1A, 1B) according to a first aspect of the present embodiment includes a substrate (2), a heat sink (4), and an integrated circuit (5). The substrate (2) has a mounting surface (21) and an attachment surface (22) facing each other in a thickness direction, and through holes (3, 3B). The heat sink (4) is attached to the attachment surface (22). The integrated circuit (5) is attached with adhesive (6) to an attachment portion (42) of the heat sink (4) facing the through hole (3) in the thickness direction. The substrate (2) includes an electrode (23) formed on the mounting surface (21). The integrated circuit (5) is electrically connected to the electrode (23) by a bonding wire (W1, W1A). The through holes (3, 3B) have a first opening (3a) formed in the mounting surface (21) and a second opening (3b) formed in the attachment surface (22). The first opening (3a) is smaller than the second opening (3b).

[0067] The above-described circuit modules (1, 1A, 1B) can shorten the bonding wires (W1, W1A) that electrically connect the integrated circuit (5) and the substrate (2).

[0068] In the circuit module (1, 1A) of the second aspect of the embodiment, in the first aspect, the through hole (3) preferably has a step (32, 34) formed on at least a portion of the circumferential direction of the inner surface of the through hole (3). The step (32, 34) makes the cross-sectional area of the through hole (3) on the side of the first opening (3a) smaller than the cross-sectional area of the through hole (3) on the side of the second opening (3b) in the thickness direction.

[0069] The above-described circuit module (1, 1A) can easily be configured so that the first opening (3a) is smaller than the second opening (3b).

[0070] In the circuit module (1, 1A) of the third aspect according to the embodiment, in the second aspect, the step portion (32, 34) is preferably formed on a part of the inner surface of the through hole (3) in the circumferential direction.

[0071] The circuit module (1, 1A) described above can reduce the processing area for the through-hole (3).

[0072] In the circuit module (1, 1A) of the fourth aspect according to the embodiment, in the second aspect, the stepped portion (32, 34) is preferably formed on the inner surface of the through hole (3) all around in the circumferential direction.

[0073] The above-described circuit module (1, 1A) can increase the number of electrodes (23).

[0074] In the circuit module (1B) of the fifth aspect of the embodiment, in the first aspect, the through hole (3B) preferably has a tapered surface (36, 38) formed on at least a portion of the circumferential direction of the inner surface of the through hole (3B). The tapered surface (36, 38) makes the cross-sectional area of the through hole (3B) on the side of the first opening (3a) smaller than the cross-sectional area of the through hole (3B) on the side of the second opening (3b) in the thickness direction.

[0075] The circuit module (1B) described above can improve the rigidity of the substrate (2).

[0076] In the circuit module (1B) of the sixth aspect according to the embodiment, in the fifth aspect, the tapered surfaces (36, 38) are preferably formed on a part of the inner surface of the through hole (3B) in the circumferential direction.

[0077] The circuit module (1B) described above can reduce the area required for processing the through-holes (3).

[0078] In the circuit module (1B) of the seventh aspect according to the present embodiment, in the fifth aspect, the tapered surfaces (36, 38) are preferably formed on the inner surface of the through hole (3B) over the entire circumferential direction.

[0079] The above-described circuit module (1B) can increase the number of electrodes (23).

[0080] In the circuit module 1A according to an eighth aspect of the present invention, in any one of the first to seventh aspects, the heat sink 4 preferably has a protrusion 43 having an attachment portion 42 on its tip surface. The protrusion 43 is located inside the second opening 3b in a plan view in the thickness direction.

[0081] The circuit module (1A) described above allows the bonding wires (W1A) that electrically connect the integrated circuit (5) and the substrate (2) to be further shortened.

[0082] In a circuit module (1, 1A, 1B) according to a ninth aspect of the present embodiment, in any one of the first to eighth aspects, the integrated circuit (5) has an adhesive surface (52) attached to the heat sink (4) with an adhesive (6) and an end surface (51) facing the adhesive surface (52). In the thickness direction of the substrate (2), the end surface (51) of the integrated circuit (5) is preferably located between the mounting surface (21) and the attachment surface (22) of the substrate (2).

[0083] The above-described circuit modules (1, 1A, 1B) allow the bonding wires (W1, W1A) that electrically connect the integrated circuit (5) and the substrate (2) to be further shortened.

[0084] In the circuit module (1, 1A, 1B) of the tenth aspect of the embodiment, in any one of the first to ninth aspects, it is preferable that at least a portion of the electrode (23) is located inside the second opening (3b) when viewed in a plane in the thickness direction.

[0085] The above-described circuit modules (1, 1A, 1B) allow the bonding wires (W1, W1A) that electrically connect the integrated circuit (5) and the substrate (2) to be further shortened. [Explanation of symbols]

[0086] 1, 1A, 1B circuit module 2 boards 21 Mounting surface 22 Mounting surface 23 electrodes 3, 3B through hole 3a 1st opening 3b 2nd opening 32, 34 Step 36, 38 Tapered surface 4 Heatsink 42 mounting location 43 Convex part 5. Integrated Circuits 51 End face 52 Adhesive surface 6. Adhesive W1, W1A Bonding Wire

Claims

1. a substrate having a mounting surface and an attachment surface facing each other in a thickness direction, and a through hole; a heat sink attached to the mounting surface; an integrated circuit attached by an adhesive to an attachment portion of the heat sink facing the through hole in the thickness direction, the substrate includes an electrode formed on the mounting surface, the integrated circuit is electrically connected to the electrodes by bonding wires; The through hole is a first opening formed in the mounting surface; a second opening formed in the mounting surface, The first opening is smaller than the second opening. Circuit module.

2. The through hole has a step portion formed on an inner surface of the through hole at least in a part of the circumferential direction of the inner surface, The step portion makes the cross-sectional area of the through hole on the side of the first opening smaller than the cross-sectional area of the through hole on the side of the second opening in the thickness direction. The circuit module of claim 1 .

3. The step portion is formed on a part of the inner surface of the through hole in the circumferential direction. The circuit module of claim 2.

4. The step portion is formed on the inner surface of the through hole over the entire circumference in the circumferential direction. The circuit module of claim 2.

5. The through hole has an inner surface of the through hole that has a tapered surface formed on at least a portion of the inner surface in a circumferential direction, The tapered surface makes the cross-sectional area of the through hole on the side of the first opening smaller than the cross-sectional area of the through hole on the side of the second opening in the thickness direction. The circuit module of claim 1 .

6. The tapered surface is formed on a part of the inner surface of the through hole in the circumferential direction. The circuit module of claim 5.

7. The tapered surface is formed on the inner surface of the through hole over the entire circumference in the circumferential direction. The circuit module of claim 5.

8. the heat sink has a protrusion having the attachment portion on a tip surface thereof, The protrusion is located inside the second opening in a plan view in the thickness direction. The circuit module according to any one of claims 1 to 7.

9. The integrated circuit comprises: an adhesive surface attached to the heat sink by the adhesive; an end surface facing the adhesive surface; In the thickness direction of the substrate, the end face of the integrated circuit is located between the mounting surface and the attachment surface of the substrate. The circuit module according to any one of claims 1 to 8.

10. At least a portion of the electrode is located inside the second opening in a plan view in the thickness direction. The circuit module according to any one of claims 1 to 9.

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