Electronic component module

Abstract

An electronic component module (101) comprise:s a substrate (1) that has a first surface (1a); a first electronic component (3a) that is mounted on the first surface (1a); a first sealing resin layer (6a) that seals the first surface (1a) and the first electronic component (3a); and a first plate (5) that covers the surface of the first sealing resin layer (6a) on the side away from the first surface (1a). The linear expansion coefficient of the substrate (1) is greater than the linear expansion coefficient of the first plate (5), and when the combination of the first sealing resin layer (6a) and the first electronic component (3a) is a first composite layer (41), the linear expansion coefficient of the first composite layer (41) is greater than the linear expansion coefficient of the substrate (1).

Description

Electronic component module

[0001] The present invention relates to an electronic component module.

[0002] An electronic component module including a substrate, an electronic component mounted on the substrate, and a sealing resin for sealing the electronic component is known. Terminals are provided on the back surface of the substrate. The electronic component module is used in a state of being mounted on a motherboard. The mounting of the electronic component module on the motherboard is performed by soldering the terminals provided on the back surface of the substrate to the motherboard.

[0003] In Japanese Patent Application Laid-Open No. 2017-168701 (Patent Document 1), paying attention to the problem that the upper surface of the sealing resin layer becomes concave and warps during heating, in order to solve this problem, a configuration in which a warp adjustment film is disposed so as to cover the upper surface of the sealing resin layer is disclosed. This warp adjustment film is formed of zinc, aluminum, manganese, etc. In Patent Document 1, by setting the elastic modulus of the warp adjustment film to be higher than that of the sealing resin layer, the thermal expansion of the sealing resin layer during heating is suppressed. Further, by forming the warp adjustment film of a material having a larger coefficient of thermal expansion than Cu, it is said that the warp in which the upper surface of the sealing resin layer is deformed into a concave shape is suppressed.

[0004] In US Patent Application US2018 / 0102342A1 (Patent Document 2), a configuration in which a three-layer reinforcing plate is disposed on the upper surface of the sealing resin to prevent warping is disclosed.

[0005] Japanese Patent Application Laid-Open No. 2017-168701 US Patent Application US2018 / 0102342A1

[0006] When the electronic component module is repeatedly exposed to temperature changes in a state of being joined to the motherboard, there is a problem that the solder joining the terminals and the motherboard causes fatigue failure due to the difference in the linear expansion coefficients of the electronic component module and the motherboard.

[0007] While Patent Document 1 may resolve the problem of warping where the upper surface of the sealing resin layer becomes concave when the temperature rises, it does not change the fact that the coefficient of thermal expansion of the electronic component module is smaller than that of the motherboard. The coefficient of thermal expansion of the sealing resin layer is smaller than that of the substrate, and the warp adjustment film can only provide enough expansion force to eliminate the warping of the electronic component module itself. If the warp adjustment film provides more expansion force than that, the electronic component module will bend in the opposite direction, and the objective stated in Patent Document 1 cannot be achieved. Since the coefficient of thermal expansion of the electronic component module is still smaller than that of the motherboard, it is not possible to resolve the problem of solder fatigue failure caused by the difference in the coefficients of thermal expansion between the electronic component module and the motherboard.

[0008] In Patent Document 2, the reinforcing plate only suppresses warping that occurs in the electronic component module itself. Simply providing a reinforcing plate on the upper surface of the sealing resin cannot eliminate the difference in the coefficient of thermal expansion between the electronic component module and the motherboard. In the configuration of Patent Document 2, the coefficient of thermal expansion of the electronic component module is inevitably smaller than that of the motherboard, and the problem of solder fatigue failure caused by the difference in the coefficients of thermal expansion between the electronic component module and the motherboard cannot be resolved.

[0009] Therefore, the present invention aims to provide an electronic component module that can suppress solder fatigue failure caused by the difference in the coefficient of thermal expansion between the electronic component module and the motherboard.

[0010] To achieve the above objective, an electronic component module according to the present invention comprises a substrate having a first surface, a first electronic component mounted on the first surface, a first sealing resin layer that seals the first surface and the first electronic component, and a first plate that covers the surface of the first sealing resin layer furthest from the first surface. The coefficient of thermal expansion of the substrate is greater than that of the first plate. If the first sealing resin layer and the first electronic component are combined to form a first composite layer, the coefficient of thermal expansion of the first composite layer is greater than that of the substrate.

[0011] According to the present invention, by sandwiching a first composite layer with a large coefficient of thermal expansion between a substrate and a first plate with small coefficients of thermal expansion, it is possible to increase the coefficient of thermal expansion of the entire electronic component module while suppressing the warping of the entire module. Therefore, the coefficient of thermal expansion of the entire electronic component module can be brought closer to that of the motherboard. Since the difference in coefficients of thermal expansion can be reduced in this way, fatigue failure of the solder caused by the difference in coefficients of thermal expansion between the electronic component module and the motherboard can be suppressed.

[0012] This is a cross-sectional view of the electronic component module in use according to Embodiment 1 of the present invention. This is a cross-sectional view of the electronic component module in use according to Embodiment 2 of the present invention. This is a cross-sectional view of the electronic component module in use according to Embodiment 3 of the present invention. This is a cross-sectional view of the electronic component module in use according to Embodiment 4 of the present invention. This is a cross-sectional view of the electronic component module in use according to Embodiment 5 of the present invention. This is a cross-sectional view of the electronic component module in use according to Embodiment 6 of the present invention. This is a graph showing how much the solder fatigue life differs between the electronic component module in Embodiment 1 of the present invention with and without the first plate.

[0013] The dimensional ratios shown in the drawings do not necessarily accurately reflect reality, and may be exaggerated for illustrative purposes. In the following explanation, the concepts of "up" or "down" do not necessarily refer to absolute up or down, but rather to relative up or down within the illustrated orientation.

[0014] (Embodiment 1) Referring to Figure 1, an electronic component module in Embodiment 1 according to the present invention will be described. Figure 1 shows a cross-sectional view of the electronic component module in use in this embodiment. The electronic component module 101 is mounted on the motherboard 501 via solder 9.

[0015] The electronic component module 101 comprises a substrate 1, a first electronic component 3a, a first sealing resin layer 6a, and a first plate 5. The substrate 1 has a first surface 1a. The substrate 1 has a second surface 1b opposite to the first surface 1a. The first electronic component 3a is mounted on the first surface 1a. The substrate 1 is a general circuit board that has the function of electrically connecting the mounted electronic component and electrically connecting to the outside of the module. The structure of the substrate 1 is not limited. The materials constituting the substrate 1 are also not limited. The first sealing resin layer 6a seals the first surface 1a and the first electronic component 3a. The first plate 5 covers the surface of the first sealing resin layer 6a that is farther from the first surface 1a. The first plate 5 is sometimes called the "top plate". The coefficient of thermal expansion of the substrate 1 is greater than that of the first plate 5. If the first encapsulating resin layer 6a and the first electronic component 3a are combined to form the first composite layer 41, then the coefficient of thermal expansion of the first composite layer 41 is greater than the coefficient of thermal expansion of the substrate 1. The relationship between the magnitudes of the coefficients of thermal expansion of each part can be expressed as an inequality as follows.

[0016] First plate 5 < Substrate 1 < First composite layer 41 In order to increase the coefficient of thermal expansion of the first composite layer 41, the coefficient of thermal expansion of the first sealing resin layer 6a should be increased. In order to increase the coefficient of thermal expansion of the first sealing resin layer 6a, the mixing ratio of silica filler included in the material of the first sealing resin layer 6a should be decreased. Adjusting the coefficient of thermal expansion of the sealing resin by changing the mixing ratio of silica filler can be done based on known techniques. The first plate 5 may be formed from a material with a high Young's modulus. By increasing the Young's modulus of the first plate 5, the electronic component module can be made less prone to distortion. The first plate 5 is not limited to a single plate of a single material. The first plate 5 may be, for example, a composite plate formed by laminating multiple plates. If the first plate 5 is a composite plate, the multiple laminated plates may include plates of multiple different types of materials.

[0017] In this embodiment, the coefficient of thermal expansion of the first composite layer 41 is greater than that of the substrate 1. Therefore, if the first plate 5 were not present, the electronic component module 101 would tend to warp convexly when the temperature rises. However, since the first plate 5 is positioned to cover the surface of the first sealing resin layer 6a that is farther from the first surface 1a, the warping of the electronic component module 101 can be suppressed. The coefficient of thermal expansion of the first plate 5 is smaller than that of the substrate 1, but the coefficient of thermal expansion of the first plate 5 can be appropriately set within a range that satisfies this condition. By sandwiching the first composite layer 41, which has a large coefficient of thermal expansion, between the substrate 1 and the first plate 5, which have small coefficients of thermal expansion, the overall coefficient of thermal expansion of the electronic component module 101 can be increased while suppressing the warping of the entire electronic component module. Therefore, the overall coefficient of thermal expansion of the electronic component module 101 can be brought closer to that of the motherboard 501. In this way, the difference in coefficients of thermal expansion can be reduced, which can suppress solder fatigue failure.

[0018] In this embodiment, while suppressing the warping of the electronic component module 101 on its own, it is also possible to suppress the warping of the entire electronic component module 101 mounted on the motherboard 501.

[0019] (Embodiment 2) Referring to Figure 2, an electronic component module in Embodiment 2 of the present invention will be described. Figure 2 shows a cross-sectional view of the electronic component module 102 in use in this embodiment. The electronic component module 102 is mounted on the motherboard 501 via solder 9. The electronic component module 102 has a so-called double-sided mounting structure.

[0020] The electronic component module 102 comprises a substrate 1 having a first surface 1a and a second surface 1b that are opposite each other, a first electronic component 3a mounted on the first surface 1a, a first sealing resin layer 6a that seals the first surface 1a and the first electronic component 3a, a first plate 5 that covers the surface of the first sealing resin layer 6a that is farther from the first surface 1a, a second electronic component 3b mounted on the second surface 1b, a second sealing resin layer 6b that seals the second surface 1b and the second electronic component 3b, and a connecting conductor 7 that penetrates the second sealing resin layer 6b in the thickness direction. The first sealing resin layer 6a and the first electronic component 3a together form the first composite layer 41. The second sealing resin layer 6b, the second electronic component 3b and the connecting conductor 7 together form the second composite layer 42. The substrate 1 and the second composite layer 42 together form the third composite layer 43. The coefficient of thermal expansion of the third composite layer 43 is greater than that of the first plate 5. The coefficient of thermal expansion of the first composite layer 41 is greater than that of the third composite layer 43. The relationship between the magnitudes of the coefficients of thermal expansion of each part can be expressed as an inequality as follows.

[0021] First plate 5 < Third composite layer 43 < First composite layer 41 In this embodiment, the third composite layer 43 can be considered to correspond to the substrate 1 in Embodiment 1. If considered in this way, the same thing as described in Embodiment 1 can be said, and the same effects as in Embodiment 1 can be obtained in this embodiment as well.

[0022] In the manufacturing process of a double-sided mounting structure product such as the electronic component module 102, there is a step in which the third composite layer 43 is handled in its entirety. It is desirable to suppress the occurrence of warping even at this stage. To achieve this, it is preferable to make the coefficient of thermal expansion of the second composite layer 42 the same as that of the substrate 1. If the coefficient of thermal expansion of the second composite layer 42 and the substrate 1 are the same, the combined third composite layer 43 can be considered as a single unit.

[0023] (Embodiment 3) Referring to Figure 3, an electronic component module in Embodiment 3 of the present invention will be described. Figure 3 shows a cross-sectional view of the electronic component module 103 in use in this embodiment. The electronic component module 103 is mounted on the motherboard 501 via solder 9.

[0024] The basic configuration of the electronic component module 103 is the same as that of the electronic component module 102 described in Embodiment 2. In the electronic component module 103, the first plate 5 includes a first plate body 50 and a shielding film 8 that covers the side of the first plate body 50 that is farther from the substrate 1. The shielding film 8 further covers the side of the first plate 5, the side of the first sealing resin layer 6a, the side of the substrate 1, and the side of the second sealing resin layer 6b.

[0025] In the electronic component module 103, the first electronic component 3a includes a plurality of component elements 3a1 and 3a2. The substrate 1 includes a plurality of conductor patterns arranged inside. Although not shown in Figure 3, a second electronic component 3b may be mounted on the second surface 1b of the first board 5.

[0026] In this embodiment as well, the same effects as those described in Embodiments 1 and 2 can be obtained. The force with which the first plate 5 bends the electronic component module is proportional to the product of the difference in the coefficients of thermal expansion between the first plate 5 and the first composite layer 41 and the cross-sectional area of ​​the first plate 5. The cross-sectional area of ​​the first plate 5 referred to here means the cross-sectional area when cut by a plane perpendicular to the plane of the paper in Figure 3.

[0027] On the other hand, the force with which the substrate 1 bends the electronic component module is proportional to the product of the difference in the coefficients of thermal expansion between the substrate 1 and the first composite layer 41 and the cross-sectional area of ​​the substrate 1. Here, the cross-sectional area of ​​the substrate 1 refers to the cross-sectional area when cut by a plane perpendicular to the plane of the paper in Figure 3.

[0028] In this embodiment, the difference in the coefficient of thermal expansion between the first plate 5 and the first composite layer 41 is greater than the difference in the coefficient of thermal expansion between the substrate 1 and the first composite layer 41. Therefore, the thickness of the first plate 5 can be set to be thinner than the thickness of the substrate 1. Table 1 shows an example of the values ​​for the thickness, coefficient of thermal expansion, and Young's modulus of each part of the electronic component module 103.

[0029]

[0030] Here, the relative magnitudes of the linear expansion coefficients of each part are set to satisfy the following inequality.

[0031] First plate 5 < Third composite layer 43 < First composite layer 41 (Embodiment 4) Referring to Figure 4, an electronic component module in Embodiment 4 according to the present invention will be described. Figure 4 shows a cross-sectional view of the electronic component module 104 in use in this embodiment. The basic configuration of the electronic component module 104 is the same as that of the electronic component module 101 described in Embodiment 1.

[0032] In the electronic component module 104, a plurality of recesses 5e are provided on the surface of the first plate 5 facing the first sealing resin layer 6a, and the first sealing resin layer 6a is formed to fit into the plurality of recesses 5e. The fact that a plurality of recesses 5e are provided means that the parts of the surface of the first plate 5 facing the first sealing resin layer 6a that are not recesses 5e can also be considered as protrusions. Therefore, it can also be said that the surface of the first plate 5 facing the first sealing resin layer 6a has irregularities. Focusing on the protrusions among the irregularities, it can also be said that a plurality of protrusions are provided on the surface of the first plate 5 facing the first sealing resin layer 6a. In Figure 4, the plurality of recesses 5e are depicted as being of the same size and formed regularly, but this is merely an example. The plurality of recesses formed on this surface may be formed irregularly.

[0033] In this embodiment as well, the same effects as those described in Embodiment 1 can be obtained. Furthermore, in this embodiment, since the interface between the first plate 5 and the first sealing resin layer 6a is not flat, the adhesion between the first plate 5 and the first sealing resin layer 6a is improved. Therefore, delamination between the first plate 5 and the first sealing resin layer 6a becomes less likely.

[0034] (Embodiment 5) Referring to Figure 5, an electronic component module in Embodiment 5 according to the present invention will be described. Figure 5 shows a cross-sectional view of the electronic component module 105 in use in this embodiment. The basic configuration of the electronic component module 105 is the same as that of the electronic component module 101 described in Embodiment 1.

[0035] In the electronic component module 105, the first plate 5 has a through hole 5f, and the first sealing resin layer 6a is formed to fit inside the through hole 5f.

[0036] In this embodiment as well, the same effects as those described in Embodiment 1 can be obtained. Furthermore, in this embodiment, the first plate 5 has through holes 5f, and the first sealing resin layer 6a is embedded inside the through holes 5f, so the adhesion between the first plate 5 and the first sealing resin layer 6a is improved. Therefore, delamination between the first plate 5 and the first sealing resin layer 6a becomes less likely.

[0037] (Embodiment 6) Referring to Figure 6, an electronic component module in Embodiment 6 of the present invention will be described. Figure 6 shows a cross-sectional view of the electronic component module 106 in use in this embodiment. The basic configuration of the electronic component module 106 is the same as that of the electronic component module 101 described in Embodiment 1.

[0038] In the electronic component module 106, an adhesive layer 15 is interposed between the first plate 5 and the first sealing resin layer 6a.

[0039] In this embodiment as well, the same effects as those described in Embodiment 1 can be obtained. Furthermore, in this embodiment, since the adhesive layer 15 is interposed between the first plate 5 and the first sealing resin layer 6a, the bonding force between the first plate 5 and the first sealing resin layer 6a is increased. Therefore, delamination between the first plate 5 and the first sealing resin layer 6a becomes less likely.

[0040] The electronic component modules in each embodiment described so far are each equipped with a first board 5. As an example, Figure 7 shows the results of a simulation showing how much the solder fatigue life of the electronic component module 101 is extended by providing the first board 5 compared to when the first board 5 is not provided. In Figure 7, "top board" refers to the first board 5. As is clear from this graph, it can be said that providing the first board 5 significantly extends the solder fatigue life compared to when the first board 5 is not provided.

[0041] Furthermore, multiple embodiments of the above-described embodiments may be used in appropriate combinations. The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, including all modifications within the meaning and scope of the claims.

[0042] 1 Substrate, 1a First surface, 1b Second surface, 3a First electronic component, 3a1, 3a2 Component elements, 3b Second electronic component, 5 First board, 5e Recess, 5f Through hole, 6a First sealing resin layer, 6b Second sealing resin layer, 7 Connecting conductor, 8 Shielding film, 9 Solder, 10 Uneven surface, 15 Adhesive layer, 41 First composite layer, 42 Second composite layer, 43 Third composite layer, 50 First board body, 101, 102, 103, 104, 105, 106 Electronic component modules, 501 Motherboard.

Claims

1. An electronic component module comprising: a substrate having a first surface; a first electronic component mounted on the first surface; a first sealing resin layer sealing the first surface and the first electronic component; and a first plate covering the surface of the first sealing resin layer furthest from the first surface, wherein the coefficient of thermal expansion of the substrate is greater than that of the first plate, and when the first sealing resin layer and the first electronic component are combined to form a first composite layer, the coefficient of thermal expansion of the first composite layer is greater than that of the substrate.

2. An electronic component module comprising: a substrate having a first surface and a second surface that are opposite to each other; a first electronic component mounted on the first surface; a first sealing resin layer that seals the first surface and the first electronic component; a first plate that covers the surface of the first sealing resin layer that is farther from the first surface; a second electronic component mounted on the second surface; a second sealing resin layer that seals the second surface and the second electronic component; and a connecting conductor arranged to penetrate the second sealing resin layer in the thickness direction, wherein the first sealing resin layer and the first electronic component together constitute a first composite layer; the second sealing resin layer, the second electronic component and the connecting conductor together constitute a second composite layer; and the substrate and the second composite layer together constitute a third composite layer, wherein the coefficient of thermal expansion of the third composite layer is greater than that of the first plate, and the coefficient of thermal expansion of the first composite layer is greater than that of the third composite layer.

3. The electronic component module according to claim 1 or 2, wherein the first plate includes a first plate body and a shielding film covering the surface of the first plate body that is farther from the substrate.

4. The electronic component module according to claim 1 or 2, wherein a plurality of recesses are provided on the surface of the first plate facing the first sealing resin layer, and the first sealing resin layer is formed to fit into the plurality of recesses.

5. The electronic component module according to claim 1 or 2, wherein the first plate has through holes, and the first sealing resin layer is formed to penetrate into the interior of the through holes.

6. The electronic component module according to claim 1 or 2, wherein an adhesive layer is interposed between the first plate and the first sealing resin layer.

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