Electronic component package and electronic circuit substrate using the same

Abstract

Provided is an electronic component package that can suppress breakage of solder bumps and achieve long life without increasing the size of the package. An electronic component package (1) includes a rectangular wiring substrate (10) and a plurality of pad electrodes (30) arranged in a lattice pattern on a bottom surface (10b) of the wiring substrate (10). The plurality of pad electrodes (30) includes circular standard pad electrodes (31) provided at positions other than the corners of the wiring substrate (10) and almond-shaped or tear-drop-shaped deformed pad electrodes (32) provided at the corners of the wiring substrate (10). The length direction of the deformed pad electrodes (32) is oriented in a diagonal direction from the corner portion to which the deformed pad electrodes (32) belong toward the center of the wiring substrate (10).

Description

Technical Field

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

[0002] If an electronic component package using LGA (Land Grid Array) or other grid-like pads is continuously subjected to temperature shrinkage or other factors, stress will be applied at the corners, causing the solder bumps that connect the electronic component package to the circuit board to break.

[0003] As a countermeasure to prevent solder bump breakage, Patent Document 1 describes a method for increasing the size of the bumps at the four corners of the electronic component package. Patent Document 2 describes a method in which square connecting pads are used at the four corners of the package, and the orientation of the square connecting pads is tilted along the diagonal of the electronic component package.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 11-097569

[0007] Patent Document 2: Japanese Patent Application Publication No. 2001-127202 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] However, in the method for increasing the size of the bumps at the four corners of the package as described in Patent Document 1, it is difficult to arrange large bumps within a limited area, and the planar dimensions of the package also become larger. In addition, due to the difference in solder amount between the bumps and the bumps of normal size outside the four corners, poor package mounting may occur.

[0010] Furthermore, in the method described in Patent Document 2, which tilts the orientation of the square connecting disc along the diagonal of the package, the gap between the connecting disc and the adjacent connecting disc is insufficient, increasing the probability of improper installation of the package.

[0011] Therefore, the object of the present invention is to provide an electronic component package that can suppress solder bump breakage and achieve a long lifespan without increasing the package size. Furthermore, the present invention provides a highly reliable electronic circuit board on which such an electronic component package is mounted.

[0012] Solution for solving the problem

[0013] To solve the above problems, the electronic component package of the present invention is characterized in that the electronic component package comprises: a rectangular wiring substrate; and a plurality of pad electrodes arranged in a grid pattern on the bottom surface of the wiring substrate, wherein the plurality of pad electrodes comprises: a circular standard pad electrode disposed at a position other than the four corners of the wiring substrate; and an almond-shaped or teardrop-shaped deformable pad electrode disposed at the four corners of the wiring substrate, wherein the length direction of the deformable pad electrode is directed diagonally from the corner to the center of the wiring substrate.

[0014] According to the present invention, even when the electronic component package is subjected to thermal stress while being surface-mounted on a motherboard, solder bump breakage can be suppressed, thus achieving a long lifespan. Therefore, a highly reliable electronic component package can be provided.

[0015] Preferably, the deformable pad electrode has: a circular portion; and a sharp portion that protrudes toward the center or corner of the wiring substrate relative to the center of the circular portion. This allows the solder bump connected to the deformable pad electrode to become longer diagonally along the wiring substrate. Therefore, solder bump breakage can be suppressed, resulting in a longer lifespan.

[0016] In this case, it is preferable that the deformable pad electrode has: a circular portion; a first sharp portion protruding toward the center of the wiring substrate relative to the center of the circular portion; and a second sharp portion protruding in the opposite direction to the first sharp portion relative to the center of the circular 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 deformable pad electrode to become longer in the diagonal direction of the wiring substrate, suppressing solder bump breakage and achieving a longer lifespan.

[0017] Preferably, the electronic component package of the present invention further includes a plurality of solder bumps respectively connected to the plurality of pad electrodes, wherein the planar shape of the solder bumps is the same as the planar shape of the pad electrodes connected to the solder bumps. This enables the suppression of breakage of the solder bumps at the four corners of the wiring substrate, thereby achieving a longer lifespan.

[0018] Furthermore, the electronic circuit board of the present invention is characterized in that it comprises: a motherboard having a plurality of connection pad electrodes; and the electronic component package of the present invention described above, which is mounted on the motherboard, wherein the pad electrodes are connected to the connection pad electrodes via solder bumps, and the planar shape of the connection pad electrodes is the same as the planar shape of the pad electrodes connected to the connection pad electrodes.

[0019] According to the present invention, the solder bumps can be lengthened in the diagonal direction of the package, thereby extending the breakage distance of the solder bumps. Therefore, an electronic circuit board with high reliability of connection between the electronic component package and the motherboard can be provided.

[0020] The effects of the invention

[0021] According to the present invention, it is possible to provide an electronic component package that can suppress solder bump breakage and achieve long life without increasing the package size, and an electronic circuit board with high reliability on which the electronic component package is mounted. Attached Figure Description

[0022] Figure 1 (a) and (b) are schematic perspective views showing the structure of an electronic component package according to an embodiment of the present invention. (a) is a view viewed from the top surface side, and (b) is a view viewed from the bottom surface side.

[0023] Figure 2 It is a schematic plan view showing the electrode layout on the bottom surface of the electronic component package.

[0024] Figure 3 This is an enlarged view of the corner of the bottom surface of the electronic component package, and it shows the shape of the deformable pad electrode in particular.

[0025] Figure 4 (a) and (b) are schematic plan views representing the shape of the deformable pad electrode.

[0026] Figure 5 The diagram shows the shape of the solder bump, (a) showing the state on the deformable pad electrode 32, and (b) showing the state separated from the deformable pad electrode.

[0027] Figure 6 It is a schematic cross-sectional view showing the structure of an electronic circuit board containing electronic component packages, indicating the state in which the electronic component packages are mounted on the motherboard.

[0028] Figure 7 This is an illustration of cracks caused by solder bumps. Detailed Implementation

[0029] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0030] Figure 1 These are schematic perspective views showing the structure of an electronic component package according to an embodiment of the present invention, (a) being a view viewed from the top surface side and (b) being a view viewed from the bottom surface side. Figure 2 It is a schematic plan view showing the electrode layout on the bottom surface of the electronic component package.

[0031] like Figure 1 As shown in (a) and (b), the electronic component package 1 includes: a wiring substrate 10; various electronic components 20 mounted on the upper surface 10a of the wiring substrate 10; a plurality of pad electrodes 30 formed on the bottom surface 10b of the wiring substrate 10; and a plurality of solder bumps 40 respectively disposed on the plurality of pad electrodes 30.

[0032] The wiring substrate 10 is preferably a multilayer wiring substrate (semiconductor-embedded substrate) with a built-in semiconductor IC chip. The wiring substrate 10 is rectangular in shape, and the length of one side is preferably 4.5 mm to 5.0 mm.

[0033] Various electronic components 20 are mounted on the upper surface 10a of the wiring substrate 10. Examples of electronic components 20 include peripheral circuit components such as chip resistors, chip capacitors, chip inductors, and oscillators.

[0034] 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, the pad electrodes 30 are disposed at all the pad electrode formation positions specified in the grid pattern, but this is not necessarily required; they can be disposed at the desired positions. The pad electrodes 30 have two shapes: circular standard pad electrodes 31 disposed at pad electrode formation positions other than the four corners of the wiring substrate 10, and almond-shaped (or teardrop-shaped) deformed pad electrodes 32 disposed 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 μm to 400 μm.

[0035] 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.

[0036] Figure 3 (a) to (c) are near the corners of the bottom surface of the electronic component package. Figure 2 An enlarged view of region M is a diagram that specifically shows the shape of the deformed pad electrode.

[0037] like Figure 3As shown in (a) to (c), the deformable pad electrode 32 is almond-shaped, having a circular portion 32a of the same size as the standard pad electrode 31 and two sharp portions 32s1 and 32s2 protruding from the circular portion 32a in opposite directions. Specifically, the deformable pad electrode 32 has a circular portion 32a, a first sharp portion 32s1 protruding from the circular portion 32a toward the center of the wiring substrate 10, and a second sharp portion 32s2 protruding from the circular portion 32a in the opposite direction to the first sharp portion 32s1. The center of the deformable pad electrode 32 is located on the diagonal DL1 connecting the corner portion 10c1 to which the deformable pad electrode 32 belongs and the corner portion on the opposite side of the corner portion 10c1. The first and second sharp portions 32s1 and 32s2 are respectively located on both sides of the extending direction of the diagonal DL1.

[0038] At least one deformable pad electrode 32 must be provided at the four corners of the wiring substrate 10 where pads are formed; none are provided outside the four corners. The first sharp portion 32s1 of the deformable pad electrode 32 faces the center of the wiring substrate 10, and the second sharp portion 32s2 faces the corner portion 10c. Therefore, the length direction of the deformable pad electrode 32 extends along the diagonal DL1 extending from the corner portion to which the deformable pad electrode belongs, through the center of the wiring substrate 10, towards the opposite corner portion.

[0039] The shape of the deformable pad electrode 32 is determined by taking into account the gap 30c between two adjacent pad electrodes. Figure 3 (a) shows the case where the first sharp portion 32s1 and the second sharp portion 32s2 protruding from the circular portion 32a of the deformable pad electrode 32 have equal lengths.

[0040] like Figure 3 As shown in (b), when the gap 30c is wider, the second sharp portion 32s2 of the deformable pad electrode 32 can be extended diagonally outward, thereby widening the width of the solder bump 40 in the diagonal direction of the wiring substrate 10. Furthermore, as... Figure 3 As shown in (c), when the gap 30c is narrow, the first sharp portion 32s1 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. Thus, the lengths of the first sharp portion 32s1 and the second sharp portion 32s2 can be different from each other or the same.

[0041] Ideally, the first pointed portion 32s1 and the second pointed portion 32s2 should be located within the gap, but they may also extend slightly. The pointed portions only need to have a pointed tip; the degree of variation in width towards the tip is not particularly limited. That is, the width variation towards the tip can be constant, the width variation can be smaller towards the tip, or the width variation can be larger towards the tip.

[0042] Figure 4 (a) and (b) are schematic plan views representing the shape of the teardrop-shaped deformable pad electrode 32.

[0043] like Figure 4 As shown in (a) and (b), the teardrop-shaped deformable pad electrode 32 has a circular portion 32a and a sharp portion 32s protruding from the circular portion 32a. Figure 4 Figure (a) shows a sharp portion 32s formed from the circular portion 32a toward the center of the substrate. Additionally, Figure 4 (b) shows a diagram in which a sharp portion 32s is formed from the circular portion 32a toward the corner of the substrate. In this way, the deformable pad electrode 32 may also have a sharp portion 32s only on one side of the diagonal DL1 direction.

[0044] As described above, solder bumps 40 are pre-attached to each pad electrode 30. The planar shape of the solder bump 40 is preferably substantially the same as that of the pad electrode 30 on which it is mounted. That is, if the planar shape of the pad electrode is circular, the solder bump is also circular; if the planar shape of the pad electrode is almond-shaped, the solder bump is also almond-shaped; if the planar shape of the pad electrode is teardrop-shaped, the solder bump is also teardrop-shaped. The method of forming the solder bump 40 is not particularly limited and can be formed by known methods such as plating or screen printing.

[0045] Figure 5 The diagram shows the shape of the solder bump 40. (a) shows the state where it is mounted on the deformable pad electrode 32, and (b) shows the state where it is separated from the deformable pad electrode 32.

[0046] like Figure 5 As shown in (a) and (b), the deformable solder bump 42 is preferably of the same shape as the deformable pad electrode 32. The deformable pad electrode 32 is connected to the motherboard-side connection pad electrode 50 via the solder bump 40, and preferably, the connection pad electrode 50 is also of the same shape as the deformable pad electrode 32. The planar dimensions of the solder bump 40 are preferably slightly smaller than those of the deformable pad electrode 32.

[0047] Figure 6 This is a schematic perspective view showing the structure of an electronic circuit board 100 containing an electronic component package 1.

[0048] like Figure 6As shown, the electronic circuit board 100 includes a motherboard 2 and an electronic component package 1 mounted on the motherboard 2. A plurality of connection pad electrodes 50 are provided on the upper surface 2a of the motherboard 2, which are opposite to a plurality of pad electrodes 30 of the electronic component package 1. The pad electrodes 30 are connected to the corresponding connection pad electrodes 50 via solder bumps 40.

[0049] The shape of the connecting pad electrode 52 connected to the deformed pad electrode 32 is preferably the same as that of the deformed pad electrode 32. That is, the connecting pad electrodes 51 other than the four corners in the connecting pad matrix within the mounting area of ​​the electronic component package 1 are preferably circular, and the connecting pad electrodes 52 at the four corners are preferably teardrop-shaped (or almond-shaped). This allows the solder bump 40 to be lengthened in the diagonal direction, thereby increasing the breakage distance of the solder bump 40.

[0050] Figure 7 This is an illustration of the cracks that occur at solder bump 40.

[0051] like Figure 7 As shown in (a) and (b), it is known that the direction of the stress applied to the electronic component package 1 due to thermal expansion and contraction is greater in the diagonal direction connecting the center of the package to the corner, and cracks 45 of the solder bumps 40 are generated in this direction.

[0052] Here, as Figure 7 As shown in (a), in the case of a circular solder bump 40, its length is the same in all directions, and its length is shorter in the direction where cracks 45 occur, therefore the solder bump 40 is prone to breakage. However, as Figure 7 As shown in (b), the solder bump 40 of this embodiment is longer in the direction of crack 45, so the generation of crack 45 can be suppressed. In addition, even if crack 45 is generated, time can be allowed before the crack 45 develops and causes the solder bump 40 to completely break.

[0053] As described above, the electronic component package 1 of 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 disposed on each pad electrode 30. The plurality of pad electrodes 30 have: circular standard pad electrodes 31 disposed at positions other than the four corners of the wiring substrate 10; and deformable pad electrodes 32 disposed at the four corners of the wiring substrate 10. The planar shape of the deformable pad electrodes 32 is almond-shaped or teardrop-shaped, and the length direction of the deformable pad electrodes 32 is oriented towards the diagonal direction of the wiring substrate 10. Therefore, breakage of the solder bumps 40 connected to the deformable pad electrodes 32 can be suppressed, and the lifespan of the solder bumps 40 can be extended. Thus, the connection reliability with the motherboard 2 can be improved.

[0054] The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. Various modifications can be made without departing from the spirit of the present invention, and these modifications are of course included within the scope of the present invention.

[0055] For example, the initial shape of the solder bump 40 before the reflow soldering process, which mounts the surface of the electronic component package 1 onto the motherboard 2, does not necessarily need to be the same as the shape of the pad electrode 30. It can also be circular in planar shape (cylindrical or spherical in three-dimensional shape). Regardless of the shape, after the reflow soldering process, the solder bump 40 matches the shape of the pad electrode 30, thus becoming approximately the same shape as the pad electrode 30. However, if the initial shape of the solder bump 40 is the same as the pad electrode 30, there is less deformation after the reflow soldering process, thus reducing the probability of poor connection.

[0056] Example

[0057] Thermal fatigue simulations were performed on the electronic component modules of the embodiments and comparative examples. In the electronic component module of the embodiment, the corner pad electrodes and solder bumps are almond-shaped, and almond-shaped connection pad electrodes are also used on the motherboard side. The planar shape of the pad electrodes and solder bumps outside the corners is set to circular. On the other hand, the electronic component module of the comparative example uses circular pad electrodes and solder bumps throughout, and all bumps are set to the same shape.

[0058] 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 used to apply the thermal stress were: heating from 25°C to 85°C, holding at 85°C for 5 minutes, cooling from 85°C to -40°C, holding at -40°C for 5 minutes, and then restoring from -40°C to 25°C, which constituted one cycle. The heating and cooling rates were set to 18°C / minute.

[0059] The simulation results show that in the comparative example's electronic component module, cracking of the solder bumps at the corners develops with increasing thermal cycling, leading to solder bump breakage at an early stage. In contrast, in the embodiment's electronic component module, even after thermal cycling that caused breakage in the comparative example, the central portion of the solder bump remains connected and does not break. Compared to the comparative example's electronic component module, the embodiment's electronic component module exhibits a durability improvement of more than 5%.

[0060] This application claims the benefit of Japanese Patent Application No. 2024-048380, filed on March 25, 2024, the entire disclosure of which is incorporated herein by reference.

[0061] Explanation of reference numerals in the attached figures

[0062] 1. Electronic component package; 2. Motherboard; 2a. Upper surface of motherboard; 10. Wiring board; 10a. Upper surface of wiring board; 10b. Bottom surface of wiring board; 10c, 10c1. Corner; 20. Electronic component; 30. Pad electrode; 30c. Gap; 31. Standard pad electrode; 32. Deformed pad electrode; 32a. Circular portion; 32s. Sharp portion; 32s1. First sharp portion; 32s2. Second sharp portion; 40. Solder bump; 41. Standard solder bump; 42. Deformed solder bump; 45. Crack; 50, 51, 52. Connecting pad electrode; 100. Electronic circuit board; DL1. Diagonal.

Claims

1. An electronic component package, characterized in that, The electronic component package includes: a rectangular wiring substrate; and multiple pad electrodes arranged in a grid pattern on the bottom surface of the wiring substrate. The plurality of pad electrodes includes: standard circular pad electrodes disposed outside the four corners of the wiring substrate; and almond-shaped or teardrop-shaped deformed pad electrodes disposed at the four corners of the wiring substrate. The length direction of the deformable pad electrode is oriented diagonally from the corner to which the deformable pad electrode belongs toward the center of the wiring substrate.

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

3. The electronic component package according to claim 1, wherein, The deformable pad electrode has: a circular portion; and a first sharp portion that protrudes toward the center of the wiring substrate relative to the center of the circular portion; And a second pointed portion, which protrudes in the opposite direction to the first pointed portion relative to the center of the circular portion.

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

5. The electronic component package according to claim 2, wherein, The electronic component package also includes multiple solder bumps that are respectively connected to the plurality of pad electrodes. The planar shape of the solder bump is the same as the planar shape of the pad electrode connected to the solder bump.

6. An electronic circuit board, characterized in that, The electronic circuit board has the following features: Mother plate, which has multiple connecting disk electrodes; and The electronic component package according to any one of claims 1 to 5, which is mounted on the motherboard, The pad electrode is connected to the connector pad electrode via solder bumps. The planar shape of the connecting pad electrode is the same as the planar shape of the solder pad electrode connected to the connecting pad electrode.

Images