Electronic component package and electronic circuit board comprising same

Abstract

[Problem] To provide an electronic component package that makes it possible to extend service life by suppressing breakage of solder bumps without increasing the package size. [Solution] An electronic component package 1 comprises a rectangular wiring board 10, and a plurality of pad electrodes 30 that are arranged in a grid on a bottom surface 10b of the wiring board 10. The plurality of pad electrodes 30 include circular standard pad electrodes 31 that are provided at positions other than the four corners of the wiring board 10, and almond-shaped or teardrop-shaped deformed pad electrodes 32 that are provided at the four corners of the wiring board 10. The longitudinal direction of each deformed pad electrode 32 is oriented in a diagonal direction from the corner portion to which the deformed pad electrode 32 belongs toward the center of the wiring board 10.

Description

Electronic component package and electronic circuit board using the same

[0001] The present invention relates to an electronic component package and an electronic circuit board on which the electronic component package is mounted.

[0002] When electronic component packages using pads arranged in a grid pattern, such as LGA (Land Grid Array), are continuously subjected to the effects of temperature shrinkage and the like, stress is applied to the corners, which can lead to breakage of the solder bumps connecting the electronic component package to the circuit board.

[0003] As a measure to prevent solder bump breakage, for example, Patent Document 1 describes a method of increasing the size of the bumps at the four corners of an electronic component package, while Patent Document 2 describes a method of employing square lands at the four corners of the package and tilting the orientation of the square lands in the diagonal direction of the electronic component package.

[0004] Japanese Patent Laid-Open No. 11-097569 Japanese Patent Laid-Open No. 2001-127202

[0005] However, the method described in Patent Document 1, which increases the bump size at the four corners of the package, makes it difficult to layout large bumps within a limited area, and the planar size of the package also increases.In addition, there is a risk of package mounting defects occurring due to the difference in solder volume compared to normal-sized bumps other than those at the four corners.

[0006] Furthermore, in the method described in Patent Document 2, in which the square lands are tilted in the diagonal direction of the package, the clearance between adjacent lands becomes insufficient, increasing the probability of package mounting defects.

[0007] Therefore, an object of the present invention is to provide an electronic component package that can suppress breakage of solder bumps and achieve a longer life without increasing the package size, and to provide a highly reliable electronic circuit board on which such an electronic component package is mounted.

[0008] In order to solve the above problem, the electronic component package according to the present invention comprises a rectangular wiring board and a plurality of pad electrodes arranged in a grid pattern on the bottom surface of the wiring board, the plurality of pad electrodes including circular standard pad electrodes provided at locations other than the four corners of the wiring board and almond-shaped or teardrop-shaped deformed pad electrodes provided at the four corners of the wiring board, and the longitudinal direction of the deformed pad electrodes is oriented diagonally from the corner portion to which the deformed pad electrodes belong toward the center of the wiring board.

[0009] According to the present invention, even when the electronic component package is subjected to thermal stress while surface-mounted on a motherboard, breakage of the solder bumps can be suppressed, thereby extending the life of the electronic component package and providing a highly reliable electronic component package.

[0010] The deformed pad electrode preferably has a circular portion and a sharp portion that protrudes from the center of the circular portion toward the center or corner of the wiring substrate. This allows the solder bump connected to the deformed pad electrode to be elongated in the diagonal direction of the wiring substrate. This prevents the solder bump from breaking and extends its lifespan.

[0011] In this case, the deformed pad electrode preferably has a circular portion, a first sharp portion protruding from the center of the circular portion toward the center of the wiring substrate, and a second sharp portion protruding in the opposite direction from the first sharp portion. Furthermore, it is preferable that the length of the first sharp portion is equal to the length of the second sharp portion. This allows the solder bump connected to the deformed pad electrode to be elongated in the diagonal direction of the wiring substrate, thereby preventing breakage of the solder bump and extending its lifespan.

[0012] The electronic component package according to the present invention further includes a plurality of solder bumps connected to the plurality of pad electrodes, and the planar shape of the solder bumps is preferably the same as the planar shape of the pad electrodes to which the solder bumps are connected, thereby preventing breakage of the solder bumps at the four corners of the wiring substrate and achieving a longer lifespan.

[0013] Furthermore, an electronic circuit board according to the present invention comprises a motherboard having a plurality of land electrodes and the above-described electronic component package according to the present invention mounted on the motherboard, wherein the pad electrodes are connected to the land electrodes via solder bumps, and the planar shape of the land electrodes is the same as the planar shape of the pad electrodes to which the land electrodes are connected.

[0014] According to the present invention, the solder bumps can be elongated in the diagonal direction of the package, and the fracture distance of the solder bumps can be increased, thereby providing an electronic circuit board with high connection reliability between the electronic component package and the motherboard.

[0015] According to the present invention, it is possible to provide an electronic component package that can suppress breakage of solder bumps and achieve a longer life without increasing the package size, and a highly reliable electronic circuit board on which the electronic component package is mounted.

[0016] FIGS. 1(a) and 1(b) are schematic perspective views showing the configuration of an electronic component package according to an embodiment of the present invention, with (a) being a view from the top side and (b) being a view from the bottom side. FIG. 2 is a schematic plan view showing the electrode layout on the bottom surface of the electronic component package. FIG. 3 is an enlarged view of a corner portion of the bottom surface of the electronic component package, particularly showing the shape of the deformed pad electrode. FIGS. 4(a) and 4(b) are schematic plan views showing the shape of the deformed pad electrode. FIG. 5 is a diagram showing the shape of a solder bump, with (a) showing the state mounted on the deformed pad electrode 32 and (b) showing the state separated from the deformed pad electrode. FIG. 6 is a schematic cross-sectional view showing the configuration of an electronic circuit board including an electronic component package, showing the state in which the electronic component package is mounted on a motherboard. FIG. 7 is an explanatory diagram of cracks that occur in solder bumps.

[0017] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0018] 1A and 1B are schematic perspective views showing the configuration of an electronic component package according to an embodiment of the present invention, in which (a) is a view from the top side and (b) is a view from the bottom side, and FIG. 2 is a schematic plan view showing the electrode layout on the bottom surface of the electronic component package.

[0019] As shown in Figures 1(a) and (b), this electronic component package 1 includes a wiring substrate 10, various electronic components 20 mounted on a top surface 10a of the wiring substrate 10, a plurality of pad electrodes 30 formed on a bottom surface 10b of the wiring substrate 10, and a plurality of solder bumps 40 provided on each of the plurality of pad electrodes 30.

[0020] The wiring board 10 is preferably a multilayer wiring board (semiconductor-embedded board) with a semiconductor IC chip built in. The wiring board 10 is preferably rectangular, with each side preferably having a length of 4.5 to 5.0 mm.

[0021] Various electronic components 20 are mounted on the upper surface 10a of the wiring board 10. The electronic components 20 include peripheral circuit components such as chip resistors, chip capacitors, chip inductors, and oscillators.

[0022] A plurality of pad electrodes 30 are arranged in a grid pattern on the bottom surface 10b of the wiring substrate 10. In this embodiment, pad electrodes 30 are provided at all pad electrode formation positions defined in the grid pattern, but this is not necessarily required; they may be provided at any necessary positions. The pad electrodes 30 come in two shapes: circular standard pad electrodes 31 provided at pad electrode formation positions other than the four corners of the wiring substrate 10, and almond-shaped (or teardrop-shaped) modified pad electrodes 32 provided at pad electrode formation positions at the four corners of the wiring substrate 10. The diameter of the standard pad electrodes 31 is preferably 200 to 400 μm.

[0023] The shape of the solder bump 40 is the same as the shape of the pad electrode 30 on which the solder bump 40 is mounted. That is, a circular standard solder bump 41 is mounted on the standard pad electrode 31, and an almond-shaped (or teardrop-shaped) deformed solder bump 42 is mounted on the deformed pad electrode 32.

[0024] 3A to 3C are enlarged views of the vicinity of the corner portion of the bottom surface of the electronic component package (area M in FIG. 2), and in particular show the shape of the deformed pad electrode.

[0025] As shown in FIGS. 3A to 3C, the modified pad electrode 32 is almond-shaped and has a circular portion 32a of the same size as the standard pad electrode 31, and two sharp portions 32s protruding in opposite directions from the circular portion 32a. １ , 32s ２ Specifically, the deformed pad electrode 32 has a circular portion 32 a and a first sharp portion 32 s protruding from the circular portion 32 a toward the center of the wiring substrate 10. １ and the first sharp portion 32s １ A second sharp portion 32s protruding in the opposite direction to the ２ The center of the deformed pad electrode 32 is located at the corner portion 10c to which the deformed pad electrode 32 belongs. １ and the corner portion 10c １ and the diagonal line DL connecting the opposite corner １ The first and second sharp points 32s are provided on the １ , 32s ２ is the diagonal DL １ are provided on both sides in the extending direction of the

[0026] At least one deformed pad electrode 32 is always provided at the pad formation positions at the four corners of the wiring substrate 10, and is not provided at any other positions. １ The second sharp portion 32s faces the center of the wiring substrate 10. ２ Therefore, the longitudinal direction of the deformed pad electrode 32 is a diagonal line DL that runs from the corner to which the deformed pad electrode belongs through the center of the wiring substrate 10 to the opposite corner. １ The extension direction of the

[0027] The shape of the deformed pad electrode 32 is determined in consideration of the clearance 30c between two adjacent pad electrodes. １ and the second sharp portion 32s ２ This shows the case where the lengths of

[0028] As shown in FIG. 3B, when the clearance 30c is large, the second sharp portion 32s of the deformed pad electrode 32 ２ 3C, when the clearance 30c is narrow, the first sharp portion 32s can be extended diagonally outward, thereby widening the width of the solder bump 40 in the diagonal direction of the wiring substrate 10. １ The first sharp portion 32s can be extended in the diagonal inward direction, thereby widening the width of the solder bump 40 in the diagonal direction of the wiring substrate 10. １ and the second sharp portion 32s ２ The lengths of the may be different from each other or may be the same.

[0029] First sharp portion 32s １ and the second sharp portion 32s ２ It is desirable that the width of the tip of the sharp portion is within the clearance range, but it may protrude slightly. The pointed portion may have a pointed tip, and the degree of change in width toward the tip is not particularly limited. In other words, the change in width may be constant toward the tip, may decrease toward the tip, or may increase toward the tip.

[0030] 4A and 4B are schematic plan views showing the shape of the teardrop-shaped modified pad electrode 32. FIG.

[0031] As shown in Figures 4(a) and (b), the teardrop-shaped deformed pad electrode 32 has a circular portion 32a and one sharp portion 32s protruding from the circular portion 32a. In Figure 4(a), the sharp portion 32s is formed from the circular portion 32a toward the center of the substrate. In Figure 4(b), the sharp portion 32s is formed from the circular portion 32a toward the corner of the substrate. In this way, the deformed pad electrode 32 has the sharp portion 32s formed on the diagonal line DL. １ It may be provided on only one side of the direction.

[0032] As described above, solder bumps 40 are pre-connected to each pad electrode 30. The planar shape of the solder bumps 40 is preferably approximately the same as that of the underlying pad electrode 30 on which they are mounted. That is, if the planar shape of the pad electrode is circular, the solder bumps will also be circular; if it is almond-shaped, the solder bumps will also be almond-shaped; and if it is teardrop-shaped, the solder bumps will also be teardrop-shaped. There is no particular method for forming the solder bumps 40, and they can be formed by well-known methods such as plating or screen printing.

[0033] 5A and 5B are diagrams showing the shape of the solder bump 40, in which (a) shows the state where the solder bump 40 is mounted on the deformed pad electrode 32, and (b) shows the state where the solder bump 40 is separated from the deformed pad electrode 32.

[0034] 5(a) and 5(b), the deformed solder bump 42 preferably has the same shape as the deformed pad electrode 32. The deformed pad electrode 32 is connected to a land electrode 50 on the motherboard side via the solder bump 40, and the land electrode 50 also preferably has the same shape as the deformed pad electrode 32. The planar size of the solder bump 40 is preferably slightly smaller than that of the deformed pad electrode 32.

[0035] FIG. 6 is a schematic perspective view showing the configuration of an electronic circuit board 100 including the electronic component package 1. As shown in FIG.

[0036] 6 , the electronic circuit board 100 includes a motherboard 2 and an electronic component package 1 mounted on the motherboard 2. A plurality of land electrodes 50 are provided on the upper surface 2 a of the motherboard 2, facing a plurality of pad electrodes 30 of the electronic component package 1, and the pad electrodes 30 are connected to the corresponding land electrodes 50 via solder bumps 40.

[0037] The shape of the land electrode 52 connected to the deformed pad electrode 32 is preferably the same as that of the deformed pad electrode 32. That is, in the land matrix within the mounting area of ​​the electronic component package 1, the land electrodes 51 other than those at the four corners are preferably circular, and the land electrodes 52 at the four corners are preferably teardrop-shaped (or almond-shaped). This allows the solder bump 40 to be elongated in the diagonal direction, thereby increasing the fracture distance of the solder bump 40.

[0038] FIG. 7 is an explanatory diagram of a crack occurring in the solder bump 40. As shown in FIG.

[0039] As shown in Figures 7(a) and (b), the direction of stress applied to the electronic component package 1 due to thermal expansion and contraction is large in the diagonal direction connecting the center and corner of the package, and it is known that cracks 45 in the solder bumps 40 occur in this direction.

[0040] 7A, in the case of a circular solder bump 40, its length is the same in all directions, and the length in the direction in which cracks 45 occur is short, making the solder bump 40 prone to fracture. However, as shown in FIG. 7B, the solder bump 40 according to this embodiment is long in the direction in which cracks 45 occur, making it possible to suppress the occurrence of cracks 45, and even if cracks 45 do occur, it is possible to buy time before the cracks 45 propagate and the solder bump 40 completely fractures.

[0041] As described above, the electronic component package 1 according to this embodiment includes a wiring substrate 10 on which an electronic component 20 is mounted, a plurality of pad electrodes 30 formed on the bottom surface 10b of the wiring substrate 10, and a plurality of solder bumps 40 provided on each pad electrode 30. The plurality of pad electrodes 30 include circular standard pad electrodes 31 provided at locations other than the four corners of the wiring substrate 10, and deformed pad electrodes 32 provided at the four corners of the wiring substrate 10. The deformed pad electrodes 32 have an almond or teardrop shape in plan view, and the longitudinal direction of the deformed pad electrodes 32 is oriented diagonally across the wiring substrate 10. This prevents breakage of the solder bumps 40 connected to the deformed pad electrodes 32, thereby extending the life of the solder bumps 40. This improves the reliability of the connection with the motherboard 2.

[0042] The above describes a preferred embodiment of the present invention, but the present invention is not limited to the above embodiment, and various modifications are possible within the scope of the present invention, and it goes without saying that these modifications are also included within the scope of the present invention.

[0043] For example, the initial shape of the solder bumps 40 before the reflow process for surface-mounting the electronic component package 1 on the motherboard 2 does not necessarily have to be the same as the pad electrodes 30, and they may have a circular planar shape (a cylindrical or spherical three-dimensional shape). Whatever the shape, the solder bumps 40 fit the shape of the pad electrodes 30 after the reflow process, so they can be made to have approximately the same shape as the pad electrodes 30. However, if the initial shape of the solder bumps 40 is the same as the pad electrodes 30, there is less deformation after the reflow process, and the probability of connection failure can be reduced.

[0044] A thermal fatigue simulation was performed on electronic component modules according to an example and a comparative example. The electronic component module according to the example employed almond-shaped pad electrodes and solder bumps in the corners, and also employed almond-shaped land electrodes on the motherboard side. The planar shapes of the pad electrodes and solder bumps other than those in the corners were circular. On the other hand, the electronic component module according to the comparative example employed circular pad electrodes and solder bumps throughout, with all bumps having the same shape.

[0045] In the thermal fatigue simulation, thermal stress was applied to the electronic component module by repeatedly changing the temperature from low to high. The temperature conditions for applying thermal stress were to increase the temperature from 25°C to 85°C, hold at 85°C for 5 minutes, decrease the temperature from 85°C to -40°C, hold at -40°C for 5 minutes, and return from -40°C to 25°C, which was one cycle. The temperature increase and decrease rates were 18°C / min.

[0046] As a result of the above simulation, in the electronic component module according to the comparative example, cracks in the solder bumps at the corners progressed as the thermal cycle increased, leading to early fracture of the solder bumps. In contrast, in the electronic component module according to the example, the center portions of the solder bumps remained connected even after the thermal cycle that led to fracture in the comparative example, and no fracture occurred. The durability of the electronic component module according to the example was improved by 5% or more compared to the electronic component module according to the comparative example.

[0047] This application claims the benefit of Japanese Patent Application No. 2024-048380, filed March 25, 2024, the entire disclosure of which is incorporated herein by reference.

[0048] REFERENCE SIGNS LIST 1 Electronic component package 2 Motherboard 2a Top surface of motherboard 10 Wiring board 10a Top surface of wiring board 10b Bottom surface of wiring board 10c, 10c １ Corner portion 20 Electronic component 30 Pad electrode 30c Clearance 31 Standard pad electrode 32 Deformed pad electrode 32a Circular portion 32s Sharp portion 32s １ First sharp part 32s ２ Second sharp portion 40 Solder bump 41 Standard solder bump 42 Deformed solder bump 45 Crack 50, 51, 52 Land electrode 100 Electronic circuit board DL １ diagonal

Claims

1. An electronic component package comprising a rectangular wiring board and a plurality of pad electrodes arranged in a grid pattern on the bottom surface of the wiring board, the plurality of pad electrodes including circular standard pad electrodes provided at all but the four corners of the wiring board and almond- or teardrop-shaped deformed pad electrodes provided at the four corners of the wiring board, the longitudinal direction of the deformed pad electrodes being oriented diagonally from the corner portion to which the deformed pad electrode belongs toward the center of the wiring board.

2. The electronic component package according to claim 1, wherein the deformed pad electrode has a circular portion and a sharp portion that protrudes from the center of the circular portion toward the center or the corner of the wiring substrate.

3. The electronic component package of claim 1, wherein the deformed pad electrode has a circular portion, a first sharp portion protruding from the center of the circular portion toward the center of the wiring substrate, and a second sharp portion protruding in the opposite direction from the first sharp portion.

4. The electronic component package according to claim 3, wherein the length of said first sharp portion is equal to the length of said second sharp portion.

5. The electronic component package according to claim 2, further comprising a plurality of solder bumps connected to each of the plurality of pad electrodes, the planar shape of each of the solder bumps being the same as the planar shape of the pad electrodes to which the solder bumps are connected.

6. An electronic circuit board comprising: a motherboard having a plurality of land electrodes; and an electronic component package according to any one of claims 1 to 5 mounted on said motherboard, wherein said pad electrodes are connected to said land electrodes via solder bumps, and the planar shape of said land electrodes is the same as the planar shape of the pad electrodes to which said land electrodes are connected.

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