Electronic device

Abstract

To provide an electronic device in which a connection defect of a solder ball is suppressed.SOLUTION: A BGA chip 10 comprises a semiconductor chip 13, a BGA substrate 11 in which the semiconductor chip 13 is mounted on a mounted surface S1 and which is mounted on a module substrate 21m via a plurality of solder balls 22, and a lid member 14 which is joined to the mounted surface while covering the semiconductor chip. In the BGA substrate, a plurality of BGA lands 12 to which the solder balls are connected is arrayed on an opposite surface S2 of the mounted surface S1. The lid member 14 is joined to the mounted surface S1 in an opposed region of a BGA land pole to which a deformable connection member in which distortion caused by a thermal cycle becomes large among the plurality of solder balls is connected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to electronic devices. [Background technology]

[0002] An example of an electronic device is a ball grid array package having a plurality of solder balls, as described in Patent Document 1. The ball grid array package is mounted on a circuit board. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-228458 Summary of the Invention [Problem to be solved by the invention]

[0004] An electronic device may include a circuit component having a plurality of electrodes arranged thereon, a component substrate on which the circuit component is mounted, and a cover member mounted on the component substrate and covering the circuit component. Such an electronic device is mounted on the circuit substrate via a plurality of connecting members. However, there is a risk that a connection failure may occur in the connecting members due to deformation of the component substrate or the like.

[0005] One disclosed object is to provide an electronic device in which connection failures of connection members are suppressed. [Means for solving the problem]

[0006] The electronic device disclosed herein comprises: Circuit components (13;20) and a component board (11; 21m) having circuit components mounted on one surface (S1; S21) and mounted on a substrate (21m; 61) via a plurality of connecting members; a cover member (14; 31) that covers the circuit components and is bonded to one surface of the component board; The component substrate has a plurality of electrodes (12; 22b) arranged on the opposite surface (S2; S22) of the one surface to which the connection member is connected, The cover member is joined on one surface to a region facing the electrode to which the deformable connection member, which is one of the plurality of connection members and which is subject to large distortion due to thermal cycling, is connected.

[0007] According to the electronic device disclosed herein, when the component board is mounted on the substrate, deformation of the component board away from the substrate at the location where the lid member is joined is suppressed, thereby suppressing connection failure of the deformed connecting member.

[0008] The various aspects disclosed in this specification employ different technical means to achieve their respective objectives. The reference numerals in parentheses in the claims and in this section are intended to exemplify correspondences with the following embodiments and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by reference to the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a plan view showing the electronic control device in the first embodiment. [Figure 2] FIG. 2 is a plan view seen from the direction of arrow II in FIG. [Figure 3] FIG. 2 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a plan view seen from the direction of arrow IV in FIG. [Figure 5] FIG. 4 is a plan view seen from the direction of arrow V in FIG. [Figure 6] FIG. 10 is a cross-sectional view of an electronic control device according to a first modified example. [Figure 7] FIG. 10 is a plan view of the housing space side of the cover member in the first modification. [Figure 8] FIG. 10 is a plan view of the housing space side of the cover member in Modification 2. [Figure 9]FIG. 11 is a plan view of the housing space side of the cover member in Modification 3. [Figure 10] FIG. 13 is a plan view of the housing space side of the cover member in Modification 4. [Figure 11] FIG. 10 is a cross-sectional view of an electronic control device at room temperature in Modification 5. [Figure 12] FIG. 13 is a cross-sectional view of an electronic control device at a low temperature in Modification 5. [Figure 13] FIG. 10 is a cross-sectional view of an electronic control device according to a second embodiment. [Figure 14] FIG. 13 is a cross-sectional view of an electronic control device according to a sixth modified example. [Figure 15] FIG. 10 is a cross-sectional view of an electronic control device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment may be assigned the same reference numerals, and duplicated explanations may be omitted. In each embodiment, when only a part of the configuration is described, other parts of the configuration can be applied by referring to the other embodiments described earlier. Each embodiment corresponds to Modifications 1 to 6, the second embodiment, and the third embodiment, which will be described later. In the following, three mutually orthogonal directions are referred to as the X direction, the Y direction, and the Z direction.

[0011] (First embodiment) An electronic control device 100 according to a first embodiment will be described with reference to Figures 1 to 5. The electronic control device 100 is configured to be mountable on, for example, a mobile body. Examples of mobile bodies include vehicles such as electric cars, hybrid cars, and fuel cell cars, flying bodies such as electric vertical take-off and landing aircraft and drones, ships, construction machinery, and agricultural machinery. However, the electronic control device 100 can be mounted on objects other than mobile bodies.

[0012] <Overall structure> As shown in Figures 1, 2, and 3, the electronic control device 100 mainly includes a module substrate 21m, a BGA chip 10 mounted on the module substrate 21m, and a case 30 that houses the module substrate 21m on which the BGA chip 10 is mounted. The electronic control device 100 also includes solder balls 21 for electrically connecting the module substrate 21m and the BGA chip 10. The solder balls 21 correspond to connecting members. In this embodiment, the solder balls 21 are used as an example of connecting members. However, the connecting members are not limited to the solder balls 21, and silver paste, conductive adhesive, etc. can also be used. Note that, hereinafter, electrical connection will also be simply referred to as connection. BGA is an abbreviation for Ball Grid Array.

[0013] Furthermore, the electronic control device 100 is provided with a second heat transfer member 42 for reducing the thermal resistance between the case 30 and the BGA chip 10. In other words, the electronic control device 100 is provided with a second heat transfer member 42 for increasing the thermal conductivity between the case 30 and the BGA chip 10. In other words, the second heat transfer member 42 is a member for improving the heat dissipation performance of the BGA chip 10. Therefore, the heat of the BGA chip 10 is dissipated to the case 30 via the second heat transfer member 42.

[0014] As shown in FIG. 3, the second heat transfer member 42 is disposed in contact with both the case 30 and the BGA chip 10. More specifically, the second heat transfer member 42 is disposed in contact with the opposing surface S12 of the case 30 (cover 31) and the top surface S11 of the BGA chip 10. The opposing surface S12 is the surface of the cover 31 that faces the BGA chip 10. The top surface S11 is the surface of the lid member 14 that faces the cover 31, which will be described later. The top surface S11 and the opposing surface S12 are disposed opposite each other. Therefore, it can be said that the second heat transfer member 42 is crushed by the top surface S11 and the opposing surface S12. In other words, the second heat transfer member 42 is disposed between the lid member 14 and the cover 31, compressed by the cover 31.

[0015] The second heat transfer member 42 may be made of a TIM such as silicone gel. TIM is an abbreviation for Thermal Interface Material. However, the second heat transfer member 42 may also be made of an adhesive or the like.

[0016] <Case> As shown in FIGS. 1 and 2, the case 30 includes a cover 31, a base 32, and screws 33. When the cover 31 and the base 32 are assembled together, a space is formed in the case 30 to accommodate the BGA chip 10 and the module substrate 21m. In addition, the cover 31 and the base 32 are fixed to each other in an assembled state by the screws 33. The screws 33 are provided, for example, at the four corners of the cover 31 and the base 32. The case 30 corresponds to a housing.

[0017] The fixing member for fixing the cover 31 and the base 32 is not limited to the screw 33. The cover 31 and the base 32 may be fixed to each other by a press-fit mechanism, a claw member, or the like.

[0018] 3, the cover 31 has a base 31a and a pressing portion 31b protruding from the base 31a. The pressing portion 31b is provided at a position facing the BGA chip 10. The pressing portion 31b is a portion that protrudes from the base 31a toward the BGA chip 10. The pressing portion 31b is disposed opposite the lid member 14, which will be described later. The pressing portion 31b corresponds to the portion disposed opposite the lid member 14.

[0019] The pressing portion 31b is provided to apply a compressive load to the second heat transfer member 42. The compressive load is applied to the second heat transfer member 42 in the direction of the white arrow in FIG. 3. The compressive load is applied to the second heat transfer member 42 in order to thin the second heat transfer member 42 and improve the heat dissipation performance of the BGA chip 10. Therefore, the pressing portion 31b applies a compressive load to thin the second heat transfer member 42. The cover 31 is fixed to the base 32 by the screws 33 as described above. Therefore, a compressive load is continuously applied to the second heat transfer member 42. Note that the white arrow here is an arrow superimposed on the cover 31.

[0020] <Module board> The module substrate 21m has conductive wiring formed on an electrically insulating substrate. The module substrate 21m is a so-called wiring substrate. As shown in FIG. 3, the module substrate 21m has a mount surface S21 on which the BGA chip 10 is mounted. Although not shown, the module substrate 21m also has a back surface that is the surface opposite to the mount surface S21. In this embodiment, the module substrate 21m corresponds to the mount substrate.

[0021] The module substrate 21m has conductive mounting surface lands 22a connected to wiring. The mounting surface lands 22a are exposed on the side of the mounted surface S21. The mounting surface lands 22a are the portions to which the solder balls 21 are connected. Therefore, the mounting surface lands 22a can be said to be electrodes of the module substrate 21m.

[0022] The module substrate 21m has a plurality of mounting surface lands 22a arranged. By "arranged," we mean that the lands are arranged two-dimensionally. In other words, the module substrate 21m has a plurality of mounting surface lands 22a arranged so that a BGA chip 10 can be mounted thereon. Naturally, the module substrate 21m may have mounting surface lands 22a other than the arranged mounting surface lands 22a.

[0023] 3 and other figures show only a portion of module substrate 21m on which one BGA chip 10 is mounted. However, module substrate 21m may have circuit elements other than BGA chip 10 mounted thereon. Circuit elements include switching elements such as MOSFETs, resistor elements, capacitor elements, and coils. Furthermore, module substrate 21m may have multiple BGA chips 10 mounted thereon.

[0024] <BGAチップ> As shown in Figures 3, 4, and 5, the BGA chip 10 includes a BGA substrate 11, BGA lands 12, a semiconductor chip 13, and a lid member 14. The BGA chip 10 can be applied to, for example, an SoC (System on a Chip). In this embodiment, the semiconductor chip 13 corresponds to a circuit component, the BGA substrate 11 corresponds to a component substrate, and the BGA lands 12 correspond to electrodes. In this embodiment, the BGA chip 10 corresponds to an electronic device. In Figure 5, the solder balls 21 are shown with dashed lines and two-dot chain lines to show the relationship between the bonding areas of the lid member 14 and BGA substrate 11 and the state of the solder balls 21.

[0025] The BGA substrate 11 has a surface S1 to be mounted and an opposite surface S2. The BGA substrate 11 also has a rectangular shape. Therefore, the surface S1 to be mounted and the opposite surface S2 also have a rectangular shape.

[0026] The BGA substrate 11 is mounted on a module substrate 21m via a plurality of solder balls 21. A semiconductor chip 13 is mounted on the mounting surface S1. A plurality of BGA lands 12 to which the solder balls 21 are connected are arranged on the opposite surface S2. The plurality of BGA lands 12 are arranged two-dimensionally, similar to the mounting surface lands 22a. Each BGA land 12 is connected to a semiconductor chip 13. The mounting surface S1 corresponds to one surface.

[0027] For example, multiple solder balls 21 are arranged as shown in FIG. 5. The BGA lands 12 are connected to the solder balls 21. That is, the BGA lands 12 are arranged opposite the solder balls 21. Therefore, the multiple BGA lands 12 are arranged in the same manner as the solder balls 21. The solder balls 21 in FIG. 5 can also be considered as multiple BGA lands 12. In this way, the solder balls 21 are connected to each BGA land 12. Therefore, the solder balls 21 can also be considered as part of the BGA chip 10.

[0028] 3, 4, and 5, lid member 14 is bonded to mounting surface S1 of BGA substrate 11 while covering semiconductor chip 13. Lid member 14 is mainly composed of a metal such as aluminum. Lid member 14 is provided to improve the heat dissipation of semiconductor chip 13.

[0029] The lid member 14 includes a lid base 14a and annular legs 14b protruding from the lid base 14a. The lid base 14a and the legs 14b of the lid member 14 form an accommodation space 14c for accommodating the semiconductor chip 13. In this embodiment, as an example, a lid member 14 having a step formed between the lid base 14a and the legs 14b is used. However, the lid member 14 does not necessarily have to have a step formed therein.

[0030] The leg portion 14b has a pressing surface 14d facing the mounting surface S1. An adhesive 50 is provided between the pressing surface 14d and the mounting surface S1. In other words, the BGA chip 10 is provided with the adhesive 50.

[0031] The lid member 14 is bonded to the BGA substrate 11 with an adhesive 50. By bonding the lid member 14 to the BGA substrate 11, the semiconductor chip 13 can be housed in a closed space. Note that the lid member 14 and the BGA substrate 11 may be bonded together by a method other than the adhesive 50.

[0032] As shown in FIG. 5, the adhesive 50 is provided in a ring shape. The adhesive 50 is provided only on a portion of the pressing surface 14d. That is, the adhesive 50 is provided only on the pressing surface 14d at the location where the BGA substrate 11 is to be bonded. The area of the lid member 14 where the adhesive 50 is provided is bonded to the BGA substrate 11. The area of the pressing surface 14d where the adhesive 50 is provided can also be referred to as the lid-side bonding area. On the other hand, the area of the mounting surface S1 where the adhesive 50 is provided can also be referred to as the board-side bonding area. The lid-side bonding area faces the board-side bonding area.

[0033] In this embodiment, as an example, substrate-side bonding regions are provided in regions facing the BGA lands 12 provided at the four corners of the BGA substrate 11 and in regions facing a plurality of BGA lands 12 provided on the outermost periphery of the BGA substrate 11. The regions facing the BGA lands 12 include not only the regions facing the BGA lands 12 but also the facing regions around the BGA lands 12.

[0034] The BGA lands 12 provided at the four corners of the BGA substrate 11 can also be called four-corner lands. The four-corner lands are the BGA lands 12 provided at each of the four corners on the opposite surface S2. On the other hand, the multiple BGA lands 12 provided at the outermost periphery of the BGA substrate 11 can also be called outermost lands. The outermost periphery lands are the multiple BGA lands 12 provided on the annular edge on the opposite surface S2. Furthermore, the solder balls 21 connected to the four corner lands can also be called four-corner solders. The solder balls 21 connected to the outermost periphery lands can also be called outermost solders.

[0035] Each of the four corner lands may include one BGA land 12 provided at the corner and three BGA lands 12 adjacent to that BGA land 12. The BGA lands 12 other than the four corner lands and the outermost periphery lands are also referred to as peripheral lands. Similarly, the solder balls 21 other than the four corner solders and the outermost periphery solders are also referred to as peripheral solders.

[0036] The multiple solder balls 21 have a different coefficient of linear expansion from the BGA substrate 11 and the module substrate 21m. Therefore, the multiple solder balls 21 may be distorted by thermal cycles. The magnitude of distortion of the multiple solder balls 21 varies depending on the location. The four corner solder and the outermost peripheral solder are more distorted by thermal cycles than the peripheral solder. The BGA chip 10 is subjected to thermal cycles when it is actually used and during durability tests. Thermal cycles are when the temperature repeatedly changes between high and low temperatures.

[0037] It can be said that the cover member 14 is bonded to the areas of the mounting surface S1 facing the four corner lands and the outermost lands. The four corner lands are BGA lands 12 to which the four corner solders of the multiple solder balls 21 that are subject to greater distortion due to thermal cycling are connected. Similarly, the outermost lands are BGA lands 12 to which the outermost solders of the multiple solder balls 21 that are subject to greater distortion due to thermal cycling are connected. The four corner solders and the outermost solder correspond to deformable connection members. Furthermore, the solder balls 21 connected to the four corner lands and the outermost lands are more likely to become deformable connection members than the other solder balls 21.

[0038] As described above, in this embodiment, the four corner lands and the outermost periphery lands are used as examples of BGA lands 12 to which the deformed connecting member is connected. However, the present disclosure is not limited to this. The BGA lands 12 to which the deformed connecting member is connected are provided at least one of the four corners of the BGA substrate 11, the outermost periphery of the BGA substrate 11, and a position facing the outer periphery of the semiconductor chip 13. Furthermore, the deformed connecting member can be considered a solder ball 21 connected to at least one of the four corner lands, the outermost periphery lands, and the peripheral lands described later.

[0039] Furthermore, the BGA chip 10 has a first heat transfer member 41 provided between the semiconductor chip 13 and the lid member 14. The first heat transfer member 41 is provided in a state compressed from the lid member 14 in the direction of the white arrow in FIG. 3 by joining the lid member 14 to the BGA substrate 11. Note that the white arrow here is an arrow illustrated superimposed on the lid base 14a. The first heat transfer member 41 may also be provided between the semiconductor chip 13 and the lid member 14 in a state compressed from the lid member 14 by a compressive load on the second heat transfer member 42.

[0040] Furthermore, leg portion 14b presses BGA substrate 11 by a compressive load on second heat transfer member 42. That is, leg portion 14b presses BGA substrate 11 in the direction of the white arrow in Fig. 3. In this case, leg portion 14b presses BGA substrate 11 in the region bonded to BGA substrate 11. The white arrow here is an arrow superimposed on leg portion 14b.

[0041] The first heat transfer member 41 can be made of the same material as the second heat transfer member 42. Here, TIM is used as an example of the first heat transfer member 41 and the second heat transfer member 42. However, the first heat transfer member 41 and the second heat transfer member 42 may be made of different materials. For example, the first heat transfer member 41 may be an adhesive, and the second heat transfer member 42 may be a silicone gel. In this embodiment, the first heat transfer member 41 also corresponds to the heat transfer member.

[0042] The state of the solder balls 21 will now be described with reference to Figures 3 and 5. The BGA chip 10 is subjected to a compressive load as described above. In this state, the multiple solder balls 21 include compressed solder 21c subjected to a compressive load and tension solder 21t subjected to a tensile load. In Figure 3, the compressed solder 21c and tension solder 21t are hatched differently to distinguish them.

[0043] A compressive load is applied to the BGA substrate 11 at the locations where the legs 14b are joined and at the locations where the semiconductor chip 13 is mounted. In other words, when the BGA substrate 11 is housed in the case 30, the locations where the legs 14b are joined and the locations where the semiconductor chip 13 is mounted are pressed by the cover 31 and a compressive load is applied. On the other hand, no compressive load is applied to the BGA substrate 11 around the locations where the legs 14b are joined and the locations where the semiconductor chip 13 is mounted. Note that the locations where no compressive load is applied can also be considered to be locations where the compressive load is smaller than the locations where the compressive load is applied.

[0044] In other words, BGA substrate 11 has portions where a compressive load is applied and portions where no compressive load is applied. Therefore, portions of BGA substrate 11 where a compressive load is applied tend to deform toward module substrate 21m, while portions where no compressive load is applied tend to deform away from module substrate 21m. Furthermore, because lid member 14 is bonded to the portions of BGA substrate 11 where lid member 14 is bonded, deformation away from module substrate 21m is suppressed.

[0045] As described above, the four corner solders and the outermost solder are provided on the surface S2 opposite to the portion where the leg portion 14b is joined. Therefore, a compressive load is applied to the four corner solders and the outermost solder. Therefore, the four corner solders and the outermost solder can be considered as compressed solder 21c. Furthermore, as shown by the two-dot chain line in FIG. 5, the solder ball 21 in the area where the adhesive 50 is provided becomes compressed solder 21c.

[0046] On the other hand, solder balls 21 (peripheral solder) other than the peripheral solder and the outermost solder are provided on the opposite surface S2 where no compressive load is applied. Therefore, a tensile load is applied to the peripheral solder. Therefore, the peripheral solder can be considered to be tensile solder 21t. Also, as shown by the dashed line in FIG. 5, the solder balls 21 in the area where no adhesive 50 is provided are tensile solder 21t.

[0047] 3, a compressive load is applied to the compression solder 21c toward the module substrate 21m, as indicated by the dashed arrow. On the other hand, a tensile load is applied to the tension solder 21t in a direction away from the module substrate 21m, as indicated by the dashed arrow. It can also be said that stress is applied to the compression solder 21c toward the module substrate 21m. It can also be said that stress is applied to the tensile solder 21t in a direction away from the module substrate 21m.

[0048] <Effects> As described above, the BGA chip 10 has a configuration in which the lid member 14 is bonded to the BGA substrate 11. The lid member 14 is bonded to the area facing the BGA lands 12 to which the four corner solders and the outermost peripheral solder are connected. Therefore, when the BGA substrate 11 is mounted on the module substrate 21m, deformation away from the module substrate 21m at the location where the lid member 14 is bonded is suppressed. Therefore, the BGA chip 10 can suppress connection failures in the four corner solders and the outermost peripheral solder. In other words, although distortion of the four corner solders and the outermost peripheral solders due to thermal cycling increases, connection failures can be suppressed. In other words, the BGA chip 10 can improve the lifespan of the four corner solders and the outermost peripheral solder.

[0049] Furthermore, compressive load is applied to the solder at the four corners and the outermost periphery of the BGA chip 10 when it is housed in the case 30. Therefore, the BGA chip 10 can further prevent poor connection of the solder at the four corners and the outermost periphery.

[0050] The preferred embodiments of the present disclosure have been described above. However, the present disclosure is not limited to the above embodiments, and various modifications are possible within the scope of the present disclosure. The present disclosure is not limited to the combinations shown in the embodiments, and can be implemented using various combinations.

[0051] (Variation 1) The BGA chip 10 of Modification 1 will be described with reference to Figures 6 and 7. In Modification 1, the configuration of the lid member 141 differs from that of the above embodiment. Figure 6 is a cross-sectional view corresponding to Figure 3. Figure 7 is a plan view corresponding to Figure 5.

[0052] As shown in Figures 6 and 7, the lid member 141 is provided with a lid protrusion 14e. The lid protrusion 14e is an annular protrusion that protrudes from the lid base 14a. The lid protrusion 14e is provided in the housing space 14c. The lid protrusion 14e is also disposed on the outer periphery of the semiconductor chip 13. In other words, the lid protrusion 14e is disposed in a position that surrounds the semiconductor chip 13. In this way, the outer periphery of the semiconductor chip 13 refers to the periphery of the semiconductor chip 13. Hereinafter, the outer periphery of the semiconductor chip 13 will also be referred to as the chip periphery.

[0053] The lid protrusion 14e is bonded to the BGA substrate 11 by the adhesive 50. That is, the lid member 141 is bonded to the BGA substrate 11 not only by the leg portions 14b but also by the lid protrusion 14e. For this reason, the adhesive 50 is provided in two ring shapes.

[0054] The BGA lands 12 provided in positions facing the chip periphery on the BGA substrate 11 can also be called peripheral lands. The peripheral lands are multiple BGA lands 12 adjacent to the facing area of the semiconductor chip 13. The solder balls 21 connected to the peripheral lands can also be called peripheral solder.

[0055] The semiconductor chip 13 has a different linear expansion coefficient from the BGA substrate 11. Therefore, the peripheral solder, like the four corner solder and the outermost periphery solder, is subject to large distortion due to thermal cycling. Therefore, the peripheral solder corresponds to a deformable connecting member.

[0056] However, the lid member 14 is bonded to the area of the BGA land 12 opposite to where the peripheral solder is connected. In other words, the peripheral solder is provided on the surface S2 opposite to the area where the lid protrusion 14e is bonded. Therefore, a compressive load is applied to the peripheral solder. Therefore, the peripheral solder can be considered as compressed solder 21c.

[0057] Therefore, when BGA substrate 11 is mounted on module substrate 21m, deformation away from module substrate 21m is suppressed at the location where lid member 14 is joined, and therefore poor connection of the peripheral solder of BGA chip 10 can be suppressed.

[0058] (Variation 2) A BGA chip 10 of Modification 2 will be described with reference to Fig. 8. Modification 2 differs from the embodiment described above in the joining location between the cover member 14 and the BGA substrate 11. Fig. 8 is a plan view corresponding to Fig. 5.

[0059] The cover member 14 is partially bonded to the outermost periphery of the BGA substrate 11. Therefore, as shown in Fig. 8, an adhesive 50 is provided on the pressing surface 14d so as to form a passage 51. The area surrounded by the adhesive 50 is connected to the outside by the passage 51. The outside refers to the space outside the area surrounded by the adhesive 50. The solder balls 21 facing the passage 51 become tensile solder 21t.

[0060] This allows the BGA chip 10 to release gas generated when the adhesive 50 hardens to the outside. The passage 51 can also be considered as a gas exhaust path. The BGA chip 10 can achieve the same effects as the above-described embodiment.

[0061] The discharge path may be configured to connect the area surrounded by the adhesive 50 to the outside. Therefore, the discharge path may be provided in the BGA substrate 11 or the lid member 14. In this case, the adhesive 50 may be provided in a ring shape.

[0062] (Variation 3) The BGA chip 10 of the third modified example will be described with reference to Fig. 9. In the third modified example, the area where the adhesive 50 is formed is different from that of the above embodiment. Fig. 9 is a plan view corresponding to Fig. 5.

[0063] 9, the adhesive 50 is applied to the entire pressing surface 14d. The solder balls 21 facing the adhesive 50 become compressed solder 21c. This allows the BGA chip 10 to increase the number of compressed solder 21c. This allows the BGA chip 10 to reduce the number of solder balls 21 that may result in poor connection.

[0064] (Variation 4) The BGA chip 10 of the fourth modification will be described with reference to Fig. 10. In the fourth modification, the configuration of the lid member 142 differs from that of the above embodiment. Fig. 10 is a plan view corresponding to Fig. 5.

[0065] 10, the shape of the pressing surface 14d1 of the cover member 142 differs from that of the above embodiment. The pressing surface 14d1 has a shape similar to that of the area where the adhesive 50 is applied in the above embodiment. Furthermore, the adhesive 50 is applied, for example, over the entire pressing surface 14d1. Therefore, the BGA chip 10 can achieve the same effects as the above embodiment.

[0066] (Variation 5) The BGA chip 10 of the fifth modification will be described with reference to Figures 11 and 12. In the fifth modification, the configuration of the lid member 143 differs from that of the above embodiment. Figures 11 and 12 are cross-sectional views corresponding to Figure 3.

[0067] As shown in FIG. 11, the lid member 143 includes a first lid base 14a1 and a second lid base 14a2. The first lid base 14a1 is an upper member in the vertical direction of the mounting surface S1. The second lid base 14a2 is a lower member in the vertical direction of the mounting surface S1. Here, the terms "upper" and "lower" refer to the relative positional relationship between the first lid base 14a1 and the second lid base 14a2. The second lid base 14a2 is a portion disposed closer to the BGA substrate 11 than the first lid base 14a1. The lid base is formed by the first lid base 14a1 and a portion of the second lid base 14a2. The leg 14b is formed by the second lid base 14a2. The first lid base 14a1 corresponds to the first lid portion. The second lid base 14a2 corresponds to the second lid portion.

[0068] The first lid base 14a1 and the second lid base 14a2 are made of different materials. The first lid base 14a1 has a smaller linear expansion coefficient than the second lid base 14a2. The first lid base 14a1 is made primarily of copper, for example. On the other hand, the second lid base 14a2 is made primarily of aluminum, for example. In this way, the lid member 143 has a bimetal structure.

[0069] 11, the lid member 143 does not deform at room temperature, and therefore the top surface S11 of the first lid base portion 14a1 is flat.

[0070] On the other hand, as shown in Figure 12, the lid member 143 deforms when the ambient temperature is low. This is because the linear expansion coefficients of the first lid base 14a1 and the second lid base 14a2 are different. Therefore, the lid member 143 deforms in the direction of the white arrow so that the center of the top surface S11 becomes convex. As a result, the lid member 143 applies stress to the solder balls 21 in the direction of the white arrow. In other words, the lid member 143 applies stress to the solder balls 21 toward the module substrate 21m.

[0071] Therefore, in addition to the compressive load, stress due to deformation of the cover member 143 is applied to the four corner solder and the outermost peripheral solder. Therefore, the BGA chip 10 can prevent poor connection of the four corner solder and the outermost peripheral solder more effectively than the above embodiment. Note that room temperature is about 25°C. Low temperature is a temperature lower than room temperature, at which solder distortion occurs.

[0072] (Second embodiment) An electronic control device 100 according to a second embodiment will be described with reference to Fig. 13. The second embodiment differs from the above-described embodiment in that it includes an MCM 20 and a motherboard 61. Fig. 13 is a cross-sectional view corresponding to Fig. 3. MCM is an abbreviation for Multi Chip Module.

[0073] 13, the electronic control device 100 includes an MCM 20 and a motherboard 61 on which the MCM 20 is mounted. The electronic control device 100 also includes a case 30, similar to the above-described embodiment.

[0074] The MCM 20 includes the BGA chips 10 and 10a and a module substrate 21m on which the BGA chips 10 and 10a are mounted. The MCM 20 is mounted on a motherboard 61.

[0075] The BGA chip 10a has a similar configuration to the BGA chip 10. That is, the BGA chip 10a includes a BGA substrate 11a having BGA lands 12a and a semiconductor chip 13a mounted on the BGA substrate 11a. However, the BGA chip 10a is provided with a sealing member 14f instead of the lid member 14. The sealing member 14f is a member that protects the semiconductor chip 13a. The sealing member 14f contacts the semiconductor chip 13a and covers the semiconductor chip 13a.

[0076] The BGA chip 10a is mounted on the mounting surface S21 of the module substrate 21m. The BGA chip 10a is connected to the mounting surface lands 22a via solder balls 22. The solder balls 22 are also connected to the BGA lands 12a. The solder balls 22 can also be considered as part of the BGA chip 10a.

[0077] The module substrate 21m has a back surface that is the surface opposite to the mounted surface S21. The back surface is an opposing surface S22 that faces the mother substrate 61. The module substrate 21m has back surface lands 22b in addition to the mounting surface lands 22a. The back surface lands 22b are connected to the wiring of the module substrate 21m and exposed on the opposing surface S22 side. The multiple back surface lands 22b are arranged on the opposing surface S22. The back surface lands 22b are portions to which solder balls 23 are connected. The module substrate 21m is mounted on the mother substrate 61 via the multiple solder balls 23.

[0078] In this embodiment, the module substrate 21m corresponds to the mounted substrate. In this embodiment, the BGA chip 10, the plurality of solder balls 21, and the module substrate 21m can be considered to be included in the electronic device. In other words, the electronic device in this embodiment includes the BGA chip 10, the plurality of solder balls 21, and the module substrate 21m.

[0079] The motherboard 61 is an electrically insulating substrate on which conductive wiring is formed. The motherboard 61 includes conductive mother lands 62 connected to the wiring. The motherboard 61 includes a plurality of mother lands 62. The mother lands 62 are exposed on the surface of the motherboard 61 on which the module substrate 21m is mounted. The plurality of mother lands 62 are arranged on the surface on which the module substrate 21m is mounted. The mother lands 62 are portions to which the solder balls 23 are connected. The motherboard 61 corresponds to a base substrate. The solder balls 23 correspond to base connecting members.

[0080] In particular, at least some of the solder balls 23 are provided in the area facing the outermost solder. In other words, the solder balls 23 are provided directly below the outermost solder.

[0081] As a result, a reaction force is applied to the outermost solder against the compressive load applied by the lid member 14. In other words, even if a compressive load is applied, the outermost solder is less likely to move toward the solder balls 23. This prevents the compressive load on the outermost solder from being released from the BGA chip 10. Therefore, the compressive load is more likely to be applied to the outermost solder of the BGA chip 10. Note that the solder balls 23 directly below the outermost solder become compressed solder 23c.

[0082] The solder balls 23 may be provided in the areas facing the four corner solders or the peripheral solders. This makes it easier for the BGA chip 10 to apply a compressive load to the four corner solders and the peripheral solders. The BGA chip 10 can achieve the same effects as the above embodiment.

[0083] In this embodiment, only a portion of the motherboard 61 on which one MCM 20 is mounted is shown. However, the motherboard 61 may also have circuit elements other than the MCM 20 mounted thereon. Furthermore, the motherboard 61 may also have multiple MCMs 20 mounted thereon.

[0084] (Variation 6) An electronic control device according to Modification 6 will be described with reference to Fig. 14. Modification 6 differs from the second embodiment in the configuration of a cover member 144. Fig. 14 is a cross-sectional view corresponding to Fig. 3.

[0085] 14, the lid member 144 is configured as an integral part with the case 30 (cover 31). The lid member 144 can be considered as part of the case 30. The first heat transfer member 41 is provided between the lid member 144 and the semiconductor chip 13 in a state of being compressed by the lid member 144.

[0086] This allows the BGA chip 10 to apply a compressive load to the four corner solders and the outermost peripheral solder from the case 30 without going through the lid member 14 or the second heat transfer member 42, which are separate from the case 30. As a result, the BGA chip 10 can improve the lifespan of the four corner solders and the outermost peripheral solder compared to the second embodiment. The lid member 144 can also be applied to Modifications 1 to 4.

[0087] (Third embodiment) An electronic control device 100 according to a third embodiment will be described with reference to Fig. 15. In the third embodiment, the configuration of the cover 31 differs from that of the above-described embodiments. Fig. 15 is a cross-sectional view equivalent to Fig. 3.

[0088] As shown in FIG. 15, the cover 31 is provided with a cover protrusion 31c. The cover protrusion 31c is a member that protrudes from the base 31a. The cover protrusion 31c is in contact with the mounting surface S21 of the module substrate 21m. The cover protrusion 31c may be bonded to the mounting surface S21 with an adhesive 50. The cover protrusion 31c presses against the mounting surface S21 by a compressive load applied to the second heat transfer member 42. Here, the state in which the cover protrusion 31c presses against the mounting surface S21 is also considered to be bonded.

[0089] Incidentally, the electronic control device 100 can be considered to correspond to an electronic device. In this case, in the electronic control device 100, the MCM 20 corresponds to a circuit component, the module substrate 21m corresponds to a component substrate, the cover 31 corresponds to a lid member, and the back surface lands 22b correspond to electrodes. The solder balls 23 correspond to connecting members, and the motherboard 61 corresponds to a mounted substrate. The mounted surface S21 corresponds to one surface, and the opposing surface S22 corresponds to the opposite surface. Furthermore, the cover protrusion 31c corresponds to a portion (leg portion 14b) of the lid member 14 that is joined to the BGA substrate 11.

[0090] Therefore, the semiconductor chip 13, BGA substrate 11, lid member 14, and BGA lands 12 of the first embodiment can be replaced with the MCM 20, module substrate 21m, cover 31, and backside lands 22b, respectively. Also, the solder balls 21 and module substrate 21m of the first embodiment can be replaced with the solder balls 23 and motherboard 61, respectively. And the mounted surface S1 and the opposite surface S2 of the first embodiment can be replaced with the mounted surface S21 and the opposing surface S22, respectively.

[0091] Furthermore, the legs 14b joined to the BGA substrate 11 in the first embodiment can be replaced with the cover protrusion 31c. That is, the cover protrusion 31c is joined to an area on the mounting surface S21 facing the back surface land 22b to which a deformable connecting member that is subject to large distortion due to thermal cycling is connected among the multiple solder balls 23.

[0092] The solder balls 23 corresponding to the four corner solders are also referred to as "board four corner solders." The solder balls 23 corresponding to the outermost periphery solders are also referred to as "board outermost periphery solders." The solder balls 23 corresponding to the periphery solders are also referred to as "board periphery solders." Therefore, the board four corner solders, the board outermost periphery solders, and the board periphery solders correspond to deformed connecting members.

[0093] The electronic control device 100 can achieve the same effects as the BGA chip 10 of the first embodiment. However, the solder balls that are the target for lifespan improvement are solder balls at the four corners of the board, solder balls at the outermost periphery of the board, solder balls around the periphery of the board, etc.

[0094] In this embodiment, the electronic control device 100 is considered to be provided with a BGA chip 10, which is also an electronic device. Specifically, the case 30 houses the BGA substrate 11 (BGA chip 10) on which the semiconductor chip 13 is mounted and the lid member 14 is joined, and the module substrate 21m on which the BGA substrate 11 is mounted. The module substrate 21m has the BGA substrate 11 mounted on a mounting surface S21, and is mounted to a motherboard 61 via a plurality of solder balls 23. The module substrate 21m has an array of a plurality of backside lands 22b, to which the solder balls 23 are connected, on an opposite surface S2 that faces the motherboard 61. The case 30 is joined to the mounting surface S21 in an area facing the backside lands 22b, to which a deformable base connecting member, which is subject to large distortion due to thermal cycles, is connected, among the plurality of solder balls 23.

[0095] In this case, the mounted surface S21 corresponds to the front surface, and the opposite surface S2 corresponds to the back surface. The solder balls 23 correspond to the base connecting members, the motherboard 61 corresponds to the base substrate, and the back surface lands 22b correspond to the base electrodes. The solder at the four corners of the board, the solder at the outermost periphery of the board, and the solder around the board correspond to the deformed base connecting members.

[0096] The electronic control device 100 can achieve the same effects as the BGA chip 10 of the first embodiment. Furthermore, the electronic control device 100 can also apply a compressive load to the solder balls 23. This can improve the lifespan of the solder balls 23. In other words, in this case, the solder balls whose lifespan is to be improved are the solder balls at the four corners of the solder balls 22 and the solder balls at the four corners of the board of the solder balls 23.

[0097] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, although various combinations and forms are shown in the present disclosure, other combinations and forms including only one element, more, or less than one element are also within the scope and spirit of the present disclosure.

[0098] (Disclosure of technical ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be written in a multiple dependent form, with the subsequent clause referring to the preceding clause as an alternative. Furthermore, some clauses may be written in a multiple dependent form, referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0099] (Technical thought 1) Circuit components (13;20) and a component board (11; 21m) on one surface of which the circuit components are mounted and which is mounted on a substrate (21m; 61) via a plurality of connecting members; a cover member (14; 31) that covers the circuit components and is bonded to the one surface of the component board; The component substrate has a plurality of electrodes (12; 22b) arranged on a surface (S2; S22) opposite to the one surface, to which the connection member is connected, The electronic device has the cover member joined on the one surface to an opposing region of the electrode to which a deformable connecting member, which is one of the plurality of connecting members and which is subject to large distortion due to thermal cycling, is connected.

[0100] (Technical thought 2) The electronic device described in Technical Idea 1, wherein the electrodes to which the deformed connecting members are connected are provided at at least one of the four corners of the component substrate, the outermost periphery of the component substrate, and a position facing the outer periphery of the circuit component.

[0101] (Technical Thought 3) The electronic device according to Technical Idea 1 or 2 further comprises an adhesive (50) that bonds the component substrate and the lid member.

[0102] (Technical Thought 4) The electronic device according to any one of Technical Ideas 1 to 3, wherein the lid member is partially joined to the outermost periphery of the component substrate.

[0103] (Technical Thought 5) The lid member has an upper first lid portion and a lower second lid portion in the vertical direction of the one surface, the upper first lid portion and the lower second lid portion being made of different materials, The electronic device according to any one of Technical Concepts 1 to 4, wherein the first lid portion has a linear expansion coefficient smaller than that of the second lid portion.

[0104] (Technical Thought 6) a plurality of the connection members and the mounted substrate; the mounted substrate is mounted on a base substrate via a plurality of base connecting members, The electronic device according to any one of Technical Concepts 1 to 5, wherein at least some of the plurality of base connecting members are provided in an opposing region to the deformable connecting member.

[0105] (Technical Thought 7) a housing (30) that houses the component board on which the circuit components are mounted and to which the lid member is joined, and the mounted substrate on which the component board is mounted; the mounted substrate has the component substrate mounted on a front surface thereof, and is mounted on a base substrate via a plurality of base connecting members, and has a back surface thereof facing the base substrate, on which a plurality of base electrodes to which the base connecting members are connected are arranged; An electronic device described in any one of technical ideas 1 to 6, wherein the housing is joined on the surface to an opposing region of the base electrode to which a deformed base connecting member, among the plurality of base connecting members, that is subject to greater distortion due to thermal cycling is connected.

[0106] (Technical Thought 8) The electronic device according to Technical Idea 7, wherein the cover member is integral with the housing.

[0107] (Technical Thought 9) The electronic device according to any one of Technical Ideas 1 to 8, further comprising a heat transfer member (41; 42) disposed between the circuit component and the cover member in a state compressed by the cover member.

[0108] (Technical Thought 10) the housing includes a portion disposed opposite the cover member, a first heat transfer member (41) disposed between the circuit component and the cover member in a state compressed by the cover member; The electronic device according to Technical Idea 7 further comprises a second heat transfer member (42) disposed between the cover member and the housing in a state compressed from the housing. [Explanation of symbols]

[0109] 10...BGA chip, 11...BGA substrate, 12...BGA land, 13...semiconductor chip, 14, 141, 142, 143, 144...lid member, 14a, 14a1, 142...lid base, 14b...leg portion, 14c...accommodation space, 14d, 14d1...pressing surface, 14e...lid protrusion, 20...MCM, 21, 22, 23...solder ball, 30...case, 31...cover, 32...base, 41...first heat transfer member, 42...second heat transfer member, 50...adhesive, 61...motherboard, 100...electronic control device

Claims

1. Circuit components (13; 20); a component board (11; 21m) on one surface of which the circuit components are mounted and which is mounted on a substrate (21m; 61) via a plurality of connecting members; a cover member (14; 31) joined to the one surface of the component substrate while covering the circuit components, The component substrate has a plurality of electrodes (12; 22b) arranged on a surface (S2; S22) opposite to the one surface, to which the connection member is connected, The electronic device has the cover member joined on the one surface to an opposing region of the electrode to which a deformable connecting member, which is one of the plurality of connecting members and which is subject to large distortion due to thermal cycling, is connected.

2. 2. The electronic device according to claim 1, wherein the electrodes to which the deformable connecting members are connected are provided at least at one of the four corners of the component substrate, the outermost periphery of the component substrate, and a position facing the outer periphery of the circuit component.

3. 3. The electronic device according to claim 1, further comprising an adhesive (50) for bonding the component substrate and the lid member together.

4. 3. The electronic device according to claim 1, wherein the lid member is partially joined to the outermost periphery of the component substrate.

5. The lid member has a first lid portion on an upper side and a second lid portion on a lower side in a vertical direction of the one surface, the first lid portion and the second lid portion being made of different materials, The electronic device according to claim 1 , wherein the first lid portion has a linear expansion coefficient smaller than that of the second lid portion.

6. a plurality of the connection members and the mounted substrate; the mounted substrate is mounted on the base substrate via a plurality of base connecting members, The electronic device according to claim 1 or 2, wherein at least some of the plurality of base connection members are provided in an area facing the deformed connection member.

7. a housing (30) that houses the component board on which the circuit components are mounted and to which the lid member is joined, and the mounted substrate on which the component board is mounted; the mounted substrate has the component substrate mounted on a front surface thereof, and is mounted on a base substrate via a plurality of base connecting members, and has a back surface thereof facing the base substrate, on which a plurality of base electrodes to which the base connecting members are connected are arranged; 3. The electronic device according to claim 1, wherein the housing is joined on the surface to an opposing region of the base electrode to which a deformed base connecting member, among the plurality of base connecting members, that is subject to greater distortion due to thermal cycling, is connected.

8. The electronic device according to claim 7 , wherein the cover member is integral with the housing.

9. 3. The electronic device according to claim 1, further comprising a heat transfer member (41; 42) disposed between the circuit component and the cover member in a state compressed by the cover member.

10. the housing includes a portion disposed opposite the cover member, a first heat transfer member (41) disposed between the circuit component and the cover member in a state of being compressed by the cover member; The electronic device according to claim 7, further comprising a second heat transfer member (42) disposed between the cover member and the housing in a state compressed from the housing.

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