JP2000114433A - Mounting structure of ball-grid-array package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of the conductive connection of a BGA with a printed circuit board, by mounting on the printed circuit board as a relaxation member one layer made of a core material having an enough area to cover the cover surface of the BGA, and by mounting the BGA on the relaxation member, and further, by mounting parts other than the BGA directly on the printed circuit board. SOLUTION: A ball-grid-array package(BGA) 1 is mounted on a printed circuit board 3 via a relaxation member 2. Then, a first wiring layer 4 is formed on the bottom surface of the printed circuit board 3, and a third wiring layer 6 is formed on its top surface. Lands are provided on the first and third wiring layers, 4, 6 to mount parts other than the BGA 1 thereon. The ball grid array of the BGA 1 is soldered 11 to the respective corresponding lands of a fourth wiring layer 7 which is provided on the top surface of the relaxation member 2, and the respective lands are connected with the third wiring layer 6 via through holes. Also, a second wiring layer 5 connects the first and third wiring layers 4, 6. Thereby, even when the printed circuit board 3 is deformed, any conductive-connection failure can be prevented from occurring between the BGA 1 and the printed circuit board 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ball grid array package (hereinafter referred to as BG).
A) (abbreviated as A) on a printed wiring board.

[0002]

2. Description of the Related Art In recent electrical products, particularly portable electrical products, semiconductor chips (chips) have been highly integrated and densified in order to realize high functionality and miniaturization. In order to mount such a semiconductor chip on a printed circuit board, the semiconductor chip is packaged in a packaging form called BGA and then mounted on the printed circuit board.

[0003] Since BGA is well known in the art, its general description is omitted, but its prior art is described in, for example, "Semiconductor Device and Mounting Structure" disclosed in JP-A-8-250553. (Hereinafter referred to as Prior Document 1), an invention entitled "Semiconductor Packaging Structure and Method for Forming Semiconductor Packaging" disclosed in JP-A-9-205163, and JP-A-10-5
There is an invention entitled "Semiconductor Package" disclosed in Japanese Patent No. 0877.

For example, the BGA proposed in Prior Document 1 is:
It is composed of three main parts, a semiconductor chip, a frame material, and a carrier substrate. A ball grid array is formed on the lower surface of the carrier substrate. The conductive connection between the semiconductor chip and the printed circuit board is made via the ball grid array. A conductive connection from the semiconductor chip to the ball grid array is made through the frame material. That is, the frame material has a surface made of an insulator, wiring is formed on the insulator, and a thermal stress at the time of mounting caused by a difference in thermal expansion coefficient between the semiconductor chip and the carrier substrate while maintaining a spring shape due to rigidity. The conductive connection between the semiconductor chip and the ball grid array of the carrier substrate is performed via a wiring pattern formed on the frame material.

[0005]

However, prior art document 1
However, there is a problem in that the above-mentioned device does not take measures for the case where the surface of the printed wiring board itself is curved. When the semiconductor chip is a lead terminal type LSI, since the lead terminals themselves are flexible and flexible, the product may be dropped or the product may be pushed into a bag or the like, resulting in stress on the product. In addition, the strength of terminal soldering is maintained even if the printed wiring board is deformed instantaneously or temporarily. In the BGA, since the ball grid array of the carrier substrate has no flexibility or flexibility, when the printed wiring board is deformed, stress is applied to a soldering portion between the ball grid array and a land on the printed wiring board. This causes problems such as weak soldering and loss of conduction in the connection portion.

FIG. 3 is a perspective view showing a conventional mounting structure of a BGA. In the drawing, reference numeral 1 denotes a BGA, 11 denotes a soldered portion between a ball grid array provided on a carrier substrate of the BGA 1 and a land on the printed wiring board, and 3 denotes a printed wiring board. The printed wiring board 3 is configured by laminating a first core material 31 and a second core material 32.
FIG. 5 is a sectional view showing a case where the printed wiring board 3 is curved in the mounting structure shown in FIG. 3, and the same reference numerals as those in FIG. 3 indicate the same parts. As is clear from FIG. 5, stress is applied to the soldering portion 11 due to the curvature of the printed wiring board 3, and the BGA
Failure may occur in the conductive connection between the first and the printed wiring board.

The present invention has been made to solve such a problem, and even if the printed wiring board is deformed for some reason, a failure occurs in the conductive connection between the BGA and the wiring of the printed wiring board. B without doing
It is intended to provide a mounting structure of a GA.

[0008]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for printing by inserting a relaxation member composed of at least one layer of a core material similar to a core material of a printed wiring board between a BGA and a printed wiring board. The influence of the curvature of the wiring board is prevented from affecting the BGA.

That is, the mounting structure of the ball grid array package of the present invention is such that the BG is mounted on a printed wiring board.
At least one layer of a core material having a sufficient width to cover the bottom surface of A is mounted on a printed circuit board as a relaxation member, and a BGA is mounted on the relaxation member. Components other than the BGA are directly mounted on the printed circuit board. I attached it. With such a structure, if the entire surface of the printed wiring board is curved for some reason, the degree of curvature of the portion where the relief member is present is significantly reduced as compared with other portions. Specifically, in a mounting structure of a ball grid array package when a ball grid array package, which is a packaging structure of a semiconductor chip, is mounted on a printed wiring board, the ball grid array package has a sufficient width to cover the bottom surface of the ball grid array package. At least one of the core material layers is mounted on the printed circuit board as a relief member, and the ball grid array package is mounted on the relief member.

[0010] In addition, parts other than the ball grid array package are directly mounted on the printed circuit board. Further, when the entire surface of the printed circuit board is curved, the curvature of the surface of the portion where the relief member exists is lessened than the curvature of the surface of the portion where the relief member does not exist. Further, when the printed board is composed of a first core material layer and a second core material layer superimposed on the upper surface of the first core material layer, the relaxation member is formed of the second core material layer. And a third core material layer superposed on the upper surface of the core material layer. Further, the first core material, the second core material, and the third core material are all made of the same material.

The relief member has an upper surface (a lower surface of the ball grid array package facing the ball grid array) on each land (lan) electrically connected to each ball grid in the ball grid array.
d) and each through hole for conductively connecting each land to each land provided at a corresponding position on the lower surface (surface opposite to the upper surface) of the relief member. . Further, the relief member is provided on its upper surface with each land electrically connected to each ball grid in the ball grid array, and each land is electrically conductive with each land provided at a corresponding position on the lower surface of the relief member. And the second core material has, on its upper surface, lands that are conductively connected to lands on the lower surface of the relaxing member, respectively.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the present invention. 1, the same reference numerals as those in FIG. 3 indicate the same or corresponding parts, and reference numeral 2 indicates a relaxation member. That is, the BGA 1 is mounted on the printed wiring board 3 via the relaxing member 2, and therefore, the reference numeral 11 denotes a BG in the case of FIG.
A soldering portion between the ball grid array provided on the carrier substrate A1 and the land on the upper surface of the relaxation member 2 is shown.

FIG. 2 is a sectional view showing the conductive connection in the embodiment shown in FIG. 2, the same reference numerals as those in FIG. 1 denote the same parts, reference numeral 4 denotes a first wiring layer, reference numeral 5 denotes a second wiring layer, reference numeral 6 denotes a third wiring layer, and reference numeral 7 denotes a fourth wiring layer. It is. The first wiring layer 4 is a wiring layer formed on the lower surface of the printed wiring board 3, and the third wiring layer 6 is a wiring layer formed on the upper surface of the printed wiring board 3;
Components other than the GA 1 are mounted with lands (or pads) provided on the third wiring layer 6 and the first wiring layer 4. BGA
Numeral 1 indicates that the ball grid array is soldered to each corresponding land of the fourth wiring layer 7 provided on the upper surface of the relaxing member 2 (reference numeral 11), and from each land to the third wiring layer 6 through a through hole. Connected. The second wiring layer 5 connects the third wiring layer 6 and the first wiring layer 4.

FIG. 4 is a cross-sectional view showing the shape of the printed wiring board 3 when the surface of the printed wiring board 3 is curved in the mounting structure shown in FIG. 1. When FIG. 4 is compared with FIG. 5, the relief member 2 is mounted. It can be seen that the curved portion has a reduced degree of curvature as compared with the portion where the relaxation member 2 is not mounted. That is, a portion having a large number of layers of the core material has a greater rigidity against bending than the other portions, and the degree of bending is reduced.
Therefore, the reliability of the conductive connection between the BGA 1 and the printed wiring board can be significantly improved by the mounting structure of the present invention.

In the above-described embodiment, the third core material used as the relaxation member uses the same material as the first and second core materials in one layer. However, the number of layers is increased to further increase the number of layers. The rigidity can be increased, and a relaxation member having high rigidity may be used.

[0016]

[Detailed description of the invention]

FIG. 1 is a perspective view showing one embodiment of a mounting structure of the present invention.

FIG. 2 is a cross-sectional view of the mounting structure of FIG.

FIG. 3 is a perspective view showing a conventional mounting structure.

FIG. 4 is a cross-sectional view showing a state where the surface of the printed wiring board is curved in the mounting structure of FIG. 1;

FIG. 5 is a cross-sectional view showing a state where the surface of the printed wiring board is curved in the mounting structure of FIG. 3;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 BGA 2 relaxation member 3 printed wiring board 4 first wiring layer 5 second wiring layer 6 third wiring layer 7 fourth wiring layer 11 soldering part 31 first core material 32 second core material

[Procedure amendment]

[Submission date] September 20, 1999 (1999.9.2)
0)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (7)

[Claims] 1. A packaging method for a semiconductor chip.
ing) ball grid array package (ba
In a mounting structure of a ball grid array package when the ll grid array package is mounted on a printed wiring board, at least one layer of a core material having a sufficient width to cover the bottom surface of the ball grid array package is provided with a relaxation member. The ball grid array package is mounted on the printed circuit board, and the ball grid array package is mounted on the relief member. 2. The mounting structure for a ball grid array package according to claim 1, wherein components other than the ball grid array package are directly mounted on the printed circuit board. 3. The mounting structure of the ball grid array package according to claim 1, wherein when the entire surface of the printed circuit board is curved, the surface of the portion where the relief member exists is curved by the presence of the relief member. A mounting structure of a ball grid array package, characterized in that the curvature is reduced from the curvature of the surface of the portion that does not. 4. The mounting structure of a ball grid array package according to claim 1, wherein said printed circuit board is overlaid on a layer of a first core material and an upper surface of said layer of said first core material. Wherein the relief member comprises a third core material layer superimposed on an upper surface of the second core material layer. Construction. 5. The mounting structure of a ball grid array package according to claim 4, wherein said first core material, said second core material, and said third core material are all made of the same material. The mounting structure of the ball grid array package characterized by the above. 6. The mounting structure of the ball grid array package according to claim 1, wherein the relief member has an upper surface (a lower surface of the ball grid array package facing the ball grid array).
Lands that are conductively connected to the ball grids in the ball grid array, and the lands are provided at corresponding positions on the lower surface (the surface opposite to the upper surface) of the relief member. What is claimed is: 1. A mounting structure of a ball grid array package, comprising: a through hole for electrically connecting to a land. 7. The mounting structure of a ball grid array package according to claim 4, wherein the relief member has on its upper surface each land electrically connected to each ball grid in the ball grid array, and each land. And each through hole for conductively connecting to each land provided at a corresponding position on the lower surface of the relief member. The second core material has an upper surface on each land on the lower surface of the relief member. A mounting structure of a ball grid array package having lands that are electrically connected to each other.