JPH11307683A - Semiconductor device, printed wiring board mounted therewith and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device provided with a land, capable of enhancing a joint between the semiconductor device and a printed wiring board, when the semiconductor device is mounted on the printed wiring board. SOLUTION: In this semiconductor device a CSP 5 has a land 7 welded to a printed wiring board 1 with a solder 9, when the CSP 5 is mounted on the wiring board 1, and a projection 7a is provided to the surface of the land 7. In the printed wiring board, a motherboard 1 has a land 3 welded to the CSP 5 with the solder 9 when the CSP 5 is mounted on the motherboard 1, and a projections are provided to the surface of the land 3. Consequently, a joint between a semiconductor device and a printed wiring board can be improved in mechanical strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device, a printed wiring board on which the semiconductor device is mounted, and a method for manufacturing the same. In particular, the present invention relates to a semiconductor device having a land capable of improving the strength of a joint between the semiconductor device and the printed wiring board when the semiconductor device is mounted on the printed wiring board, a printed wiring board, and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIG. 8 is a cross-sectional view showing a state in which a semiconductor device is bonded on a conventional printed wiring board. This semiconductor device is constituted by a CSP (Chip Sized Package) 105, for example. Land 1 on the surface of mother substrate 101
03 is formed. CSP on mother board 101
The CSP 105 has a land 107 formed on the lower surface thereof. The mounting of the CSP 105 on the motherboard 101 is performed by joining the lands 107 of the CSP and the lands 103 of the motherboard with solder 109. In addition, the lands 103 and 107 have a columnar shape, and their main surfaces are formed flat.

[0003]

The CSP 10
Since there is a difference in the coefficient of thermal expansion between 5 and the mother board 101, a stress in the lateral direction is generated at the solder joint 109 joining the CSP and the mother board. The solder of the joint 109 is hard, and the lands 103 and 107 and the solder 109
Since the strength of the joint is not always sufficient, the stress in the lateral direction often causes a failure such as "crack" or "break" at the joint.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and has as its object to improve the strength of a joint between a semiconductor device and a printed wiring board when the semiconductor device is mounted on the printed wiring board. It is an object of the present invention to provide a semiconductor device, a printed wiring board, and a method for manufacturing the same, which have lands that can be operated.

[0005]

In order to solve the above-mentioned problems, a semiconductor device according to the present invention is a semiconductor device having a land joined by solder when mounted on a printed wiring board. A convex portion or a concave portion is formed on the surface.

Further, a printed wiring board according to the present invention is a printed wiring board having a land joined by soldering when mounting a semiconductor device, and a projection or a depression is formed on the surface of the land. It is characterized by the following.

Further, a method of manufacturing a printed wiring board according to the present invention is a method of manufacturing a printed wiring board having lands joined by solder when mounting a semiconductor device, wherein a cylindrical land is formed on the surface. Preparing a substrate,
A step of forming a resist film having a predetermined pattern on the main surface of the land; and a step of etching the land using the resist film as a mask.

In the semiconductor device, the printed wiring board on which the semiconductor device is mounted, and the method for manufacturing the same, the contact area between the land and the solder can be increased by forming a convex or a concave on the surface of the land, and the solder bonding The strength of the part can be improved. Therefore, for example, even when a stress is generated in the bonding portion in the lateral direction (XY direction) at the time of thermal expansion due to a difference in thermal expansion coefficient between the semiconductor device and the printed wiring board,
The occurrence of failures such as "cracks" or "ruptures" at the joints can be reduced and suppressed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a state where a semiconductor device is bonded on a printed wiring board according to an embodiment of the present invention. FIG. 2A is a plan view of the land shown in FIG. 1, and FIG. 3A is a perspective view of the land shown in FIG.

As shown in FIG. 1, this semiconductor device is constituted by a CSP (Chip Sized Package) 5, for example. The land 3 is formed on the surface of the mother substrate 1. A CSP 5 is mounted on the mother board 1, and a land 7 is formed on a lower surface of the CSP 5. The mounting of the CSP 5 on the mother board 1 is performed by joining the lands 7 of the CSP and the lands 3 of the mother board with solder 9.

The land 7 of the CSP is shown in FIGS.
As shown in (a), it has a columnar shape, and has a projection 7a formed on its main surface. The projection 7a has a projection on its main surface (a stepped shape).
When viewed from above, the main surface has the shape of "one character."

According to the above embodiment, the contact area between the land 7 and the solder 9 is made larger than that of the conventional land by forming the land 7 of the CSP into a shape having the convex portion 7a on its main surface. Thus, the mechanical strength of the solder joint 9 can be improved. Thus, for example, C
When a stress in the lateral direction (XY direction) is generated in the bonding portion 9 during thermal expansion due to a difference in the thermal expansion coefficient between the SP5 and the mother substrate 1, the conventional land 107 shown in FIG. In many cases, a failure such as "crack" or "break" occurs, but the land 7 according to the present embodiment can reduce and suppress the occurrence of the failure. In other words, the stress in the lateral direction caused by the difference in the coefficient of thermal expansion is increased, and the life at the solder joint 9 between the mother board 1 and the CSP 5 can be extended.

In the above embodiment, a land having a convex portion 7a on the main surface is used as the land 7 of the CSP, and a land having a flat main surface is used as the land 3 of the mother substrate. The land of the CSP may be a land having a flat main surface, and the land of the mother substrate may be a land having a convex portion formed on the main surface, and the land of the CSP and the land of the mother substrate may be used. Alternatively, a land having a convex portion formed on the main surface may be used.

FIGS. 2B to 2D are plan views showing modified examples of the land shown in FIG. 2A. FIG. 3B is a perspective view showing a modified example of the land shown in FIG. 3A and showing a land having a concave portion formed on the main surface.

As shown in FIG. 2B, in the first modified example, the planar shape of the convex portion 17a formed on the main surface of the land 17 is a cross-shaped shape.

As shown in FIG. 2C, in the second modification, the planar shape of the convex portion 27a formed on the main surface of the land 27 has a constant thickness extending radially from the center of the main surface. It is in the form of a line.

As shown in FIG. 2D, in the third modification, the planar shape of the convex portion 37a formed on the main surface of the land 37 is changed to a "maru" shape (a circular shape having a certain thickness). ).

As shown in FIG. 3B, the fourth modification does not form a convex portion on the main surface of the land but forms a concave portion 47a on the main surface of the land 47 as described above. (Conversely, it is recessed). This recess 47
The planar shape of “a” is the same as the “cross-shaped” shape shown in FIG.

The same effects as those of the embodiment can be obtained in the first to fourth modifications.

The shapes of the convex portions or concave portions of the lands shown in FIG. 2 and FIG. 3 are representative examples, and other shapes are possible. That is, as long as a convex portion or a concave portion is formed on the main surface of the land, it is possible to use various shapes for the shape of the convex portion or the concave portion. Obtainable.

FIGS. 4 to 7 are views showing a method of forming a land according to the present embodiment. First, as shown in FIG. 4, a printed wiring board 22 having a land 20 formed on the surface is prepared.

Next, as shown in FIGS. 5 (a) and 5 (b),
On the main surface (front surface) of the land 20, the planar shape is "one character"
Is formed.

Thereafter, as shown in FIGS. 6A and 6B, the land 20 is etched by using the resist film 24 as a mask, so that the projection 26 is formed on the main surface of the land 20.
To form At this time, the height of the convex portion 26 is adjusted according to the length of the etching time.

Next, as shown in FIGS. 7A and 7B,
By removing the resist film 24, a land (convex land) 20 having a one-letter convex is completed.

The other lands are formed in the same manner as described above.

In the above-mentioned land forming method, the conventional substrate processing technology can sufficiently cope. For this reason, there is no demerit in the production cost of the land.

In the above embodiment, the present invention is applied to a CSP.
5, the present invention is applied to an LGA (Land Grid Array).
package).

Although the present invention is applied to the solder joint 9 between the CSP 5 and the mother board 1, the present invention can be applied to the solder joint between the interposer and the mother board. .

[0029]

As described above, according to the present invention, a projection or a depression is formed on the surface of a land. Therefore, it is possible to provide a semiconductor device, a printed wiring board, and a method of manufacturing the semiconductor device having a land capable of improving the strength of a joint between the semiconductor device and the printed wiring board when the semiconductor device is mounted on the printed wiring board. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a state in which a semiconductor device is mounted on a printed wiring board according to an embodiment of the present invention.

2A is a plan view of a land shown in FIG. 1, and FIGS. 2B to 2D are plan views showing a modification of the land shown in FIG. 2A. .

FIG. 3A is a perspective view of a land shown in FIG. 2A, and FIG. 3B is a perspective view showing a modification of the land shown in FIG. 3A.

FIG. 4 is a cross-sectional view showing a method of forming a land according to the embodiment.

5A and 5B show a method of forming a land according to the present embodiment. FIG. 5A is a cross-sectional view showing a step subsequent to that of FIG. 4, and FIG. FIG. 2 is a plan view of the land shown in FIG.

6A and 6B illustrate a method of forming a land according to the present embodiment. FIG. 6A is a cross-sectional view illustrating a step subsequent to that of FIG. 5, and FIG. FIG. 2 is a plan view of the land shown in FIG.

7A and 7B show a method of forming a land according to the present embodiment. FIG. 7A is a cross-sectional view showing a step subsequent to FIG. 6, and FIG. FIG. 2 is a plan view of the land shown in FIG.

FIG. 8 is a cross-sectional view showing a state in which a semiconductor device is mounted on a conventional printed wiring board.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Mother board, 3 ... Land, 5 ... CSP, 7 ... Land, 7a ... Convex part, 9 ... Solder joint part, 17 ... Land, 1
7a: convex portion, 20: land, 22: printed wiring board, 24
... Resist film, 26 ... Convex, 27 ... Land, 27a ... Convex, 37 ... Land, 37a ... Convex, 47 ... Land, 47
a: recess, 101: mother board, 103: land, 10
5 CSP, 107 land, 107a side surface, 109
... Solder.

Claims (5)

[Claims] 1. A semiconductor device having a land joined by solder when mounted on a printed wiring board, wherein a projection or a depression is formed on the surface of the land. 2. The semiconductor device according to claim 1, wherein the planar shape of the convex portion or the concave portion is one-character, cross-shaped, radial or round. 3. A printed wiring board having a land to be joined by solder when mounting a semiconductor device, wherein the land has a convex portion or a concave portion formed on a surface thereof. 4. The printed wiring board according to claim 3, wherein the planar shape of the convex portion or the concave portion is one-character, cross-shaped, radial or round. 5. A method for manufacturing a printed wiring board having lands joined by solder when mounting a semiconductor device, the method comprising: preparing a board having cylindrical lands formed on a surface thereof; A method of manufacturing a printed wiring board, comprising: a step of forming a resist film having a predetermined pattern on a main surface; and a step of etching the land using the resist film as a mask.