JPH098166A - Package equipment - Google Patents

Abstract

(57) [Summary] [Object] The present invention is most characterized in that it is possible to reduce the occurrence of solder bridges in a BGA package without lowering the reliability of bonding. [Structure] For example, a large area ball mounting pad 12a having a diameter of 0.5 mm and a small area ball mounting pad 12b having a diameter of 0.3 mm are alternately arranged on the lower surface of a package body 11 on which a semiconductor chip 15 is mounted. Arrange in a grid pattern. Then, 0.7 is applied to each of the pads 12a and 12b.
The solder balls 13 having a diameter of mm are fixed by the solder paste 14. At this time, the pitch interval of the solder balls 13 is 1.0
The pads 12a and 12b are arranged so as to have a size of mm. In this way, the gap between the pads 12a and 12b is widened to prevent the generation of solder bridges, and at the same time, the solder paste 14 necessary for holding is sufficiently secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called ball grid array (Ball Grid Ar) in which ball electrodes are fixed to a package body through pads.
ray) type package device.

[0002]

2. Description of the Related Art In recent years, a BGA package in which spherical ball electrodes are arranged in a grid pattern on the upper surface or the lower surface of a package body has been put into practical use as a multi-pin small package device. This BGA package is a PGA (Pin
Compared to Grid Array) packages, they are superior in packaging cost and mountability, and are expected to expand the scope of application.

FIG. 7 schematically shows the structure of a conventional BGA package. It should be noted that FIG. 7A is a top view showing the inside of the BGA package as seen through, and FIG.
A bottom view of the GA package and FIG. 7C are schematic sectional views taken along the line AA of FIG.

That is, in the BGA package, a plurality of disc-shaped ball mounting pads 2 are arranged in a grid on the lower surface of a package body (land grid array) 1 formed by laminating ceramics or plastics, for example. Solder balls 3 of the same size are brought into contact with each of the pads 2 and fixed by a solder paste 4, and a semiconductor chip 5 is mounted on the package body 1.
The upper surface is covered with the ridge portion 6.

Each chip electrode (not shown) arranged on the upper surface of the semiconductor chip 5 is wire-bonded to each of the wiring patterns 7 arranged so as to surround the chip mounting portion. , And is electrically connected to each of the solder balls 3 via the internal wiring 8 such as a through hole.

As a BGA package having such a structure, for example, as shown in FIG. 8, for example, a ball mounting pad 2 having a diameter of 0.5 mm is spaced by 0.5 mm from a package body 1 of about 20 mm square. Place the solder balls 3 with a diameter of 0.7 mm on each pad 2 and 1.0 mm.
They are fixed at a pitch interval of 324 to realize a 324 multi-pin small package.

However, in the above-mentioned conventional BGA package, there is a problem that it is difficult to achieve both the solderability and the solder strength in consideration of the distance between the adjacent pads 2.

That is, in the BGA package, since the solder balls 3 are spherical, the holding force may be weak, and the balls 3 move when the paste 4 is melted (during solder reflow), whereby the pads 2 are connected to each other by the solder paste. However, there is a drawback that the solder bridge 9 that is electrically connected by 4 is likely to occur. This is because the space between the adjacent pads 2 is 0.
It is difficult to prevent even in the case of 5 mm, and it is difficult to correct and repair it due to the large number of pins.

As a countermeasure against this, in order to improve the holding power,
It is possible to increase the area of the pad 2 and increase the amount of the solder paste 4. However, increasing the area of the pads 2 narrows the interval between the pads 2, so that the holding force is increased, while the solder bridge 9 is more likely to be generated as the amount of the paste 4 is increased.

As another measure for preventing the generation of the solder bridge 9, it is conceivable to reduce the size (area) of the pads 2 to further increase the mutual spacing.
However, simply reducing the size of the pad 2 leads to a decrease in the amount of the solder paste 4 for holding the solder ball 3, and thus the holding force is lowered, resulting in deterioration of the reliability of the bonding.

[0011]

As described above, in the related art, there is a problem that the spacing between the pads is narrow and a solder bridge is apt to occur. To prevent this, if the size of the pad is reduced, the holding force is reduced. However, there is a drawback in that the reliability of the bond is deteriorated due to the decrease of.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a package device capable of reducing the occurrence of defects such as solder bridges without deteriorating the reliability of coupling.

[0013]

In order to achieve the above object, in a package device of the present invention, a land grid array for mounting a semiconductor chip is mounted on a printed wiring board. In the ball grid array type in which solder balls are fixed, the land
At least two types of pads for fixing the solder balls to each other are arranged in a grid array in a grid array.

[0014]

According to the present invention, the above-mentioned means makes it possible to effectively expand the pad interval while securing the absolute amount of solder required for holding, so that the solderability and soldering strength of the solder ball can be improved. It is possible to achieve both.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a BGA (Ball) according to the present invention.
Grid Array) package structure is schematically shown. Note that FIG. 7A is a top view showing the inside of the BGA package as seen through, FIG. 7B is a bottom view of the BGA package, and FIG. 7C is along the line AA in FIG. It is a schematic sectional drawing.

That is, this BGA package has a package main body (land grid array) 11 formed by laminating ceramics or plastics, for example,
A plurality of large and small ball mounting pads 12a and 12b having different areas are alternately arranged in a grid pattern, and the solder balls 1 of the same size are provided on the pads 12a and 12b, respectively.
3 is abutted and fixed by the solder paste 14, and the semiconductor chip 1 is mounted on the package body 11.
5 is mounted and the upper surface thereof is covered with the ridge portion 16.

A plurality of wiring patterns 17 are arranged on the package body 11 so as to surround the chip mounting portion on which the semiconductor chip 15 is mounted. And
Each of the wiring patterns 17 is individually connected to an internal wiring 18 such as a through hole or a laminated wiring arranged inside the package body 11, and the ball mounting pad 12 is formed.
a, 12b.

Therefore, each chip electrode (not shown) arranged on the upper surface of the semiconductor chip 15 is
By wire bonding connection with each of the wiring patterns 17 on the package body 11, the solder balls 13 are electrically connected.

In the case of this embodiment, for example, 20 mm
This is a multi-pin small package in which 324 solder balls 13 are fixed to the package body 11 having a corner size.

The arrangement pattern of the ball mounting pads 12a and 12b and the solder balls 13 will be specifically described below by taking this multi-pin small package as an example.
FIG. 2 shows an arrangement pattern of the ball mounting pads 12a and 12b in the package body 11.

That is, on the lower surface of the package body 11, for example, a disc-shaped mounting pad 1 having a diameter of 0.5 mm.
2a and the disk-shaped mounting pads 12b having a diameter of 0.3 mm are arranged alternately and in a grid pattern. The mounting pads 12a and 12b are arranged with a pitch interval of 1.0 mm to the centers thereof, and the mutual distance (spacing) in the vertical and horizontal directions is expanded to 0.6 mm.

In this way, the mounting pad 12a having a large area is formed.
By arranging the mounting pads 12b having a small area with each other, the distance between the pads 12a and 12b can be expanded to 0.6 mm, and compared with the conventional device in which all the pad areas are the same, It becomes possible to suppress the occurrence of solder bridges.

3 and 4 show layout patterns of the solder balls 13 in the BGA package.
3 is a perspective view showing a main part of the BGA package, and FIG. 4 is a side view of the main part.

That is, the pads 1 arranged in a grid pattern.
Spherical solder balls 13 having the same size, for example, a diameter of 0.7 mm, are fixed onto the solder paste 2a and 12b by solder pastes 14, respectively.

In this case, two types of mounting pads 12a and 12b having different areas of 0.5 mm diameter and 0.3 mm diameter are used.
By alternately arranging the solder paste, the solder paste 1 required for holding is smaller than the case where all the pads are uniquely made small.
It is possible to secure a sufficient amount of 4.

Particularly, by arranging the pads 12a having a large area at the key points of the package main body 11, for example, at the corners of the package main body 11 to which the largest external force is applied, the reliability of bonding at the time of mounting is increased. It will not be damaged.

As described above, the space between the ball mounting pads can be effectively expanded while ensuring the absolute amount of the solder paste required for holding. That is, the ball mounting pads having different diameters (areas) are alternately arranged in a grid pattern. As a result, the distance between the pads can be widened, and the amount of solder paste required for holding can be sufficiently secured. Therefore, the solderability and the soldering strength of the solder balls can be made compatible, so that the occurrence of defects such as bridges can be reduced without impairing the reliability of bonding.

In the above embodiment, the BGA package in which the ball mounting pads of different sizes are alternately arranged has been described, but the present invention is not limited to this.
For example, as shown in FIG. 5, the size of the ball mounting pad may be changed depending on the main part of the package body 11 and other parts.

In this case, for example, as shown in FIG. 6, the large area ball mounting pads 1a are provided only at the positions corresponding to the respective corners of the package main body 11 to which an external force is applied, and the small area balls are provided at other positions. By arranging the mounting pads 12b, substantially the same effect as that of the above-described embodiment can be expected.

The size of the package body and the number of solder balls are not limited to those in the above embodiment. Of course, various modifications can be made without departing from the scope of the present invention.

[0031]

As described above in detail, according to the present invention, it is possible to provide a package device capable of reducing the occurrence of defects such as solder bridges without deteriorating the reliability of coupling.

[Brief description of drawings]

FIG. 1 is a configuration diagram schematically showing a BGA package according to an embodiment of the present invention.

FIG. 2 is a plan view of an essential part for explaining a layout pattern of ball mounting pads in the BGA package.

FIG. 3 is a perspective view of an essential part for explaining an arrangement pattern of solder balls in a BGA package.

FIG. 4 is a side view of the main part shown for explaining the arrangement pattern of solder balls in the BGA package.

FIG. 5 is a schematic configuration diagram of a BGA package according to another embodiment of the present invention.

FIG. 6 is a plan view of an essential part for explaining an arrangement pattern of ball mounting pads in the BGA package.

FIG. 7 is a B shown for explaining the related art and its problems.
The schematic block diagram of GA package.

FIG. 8 is a schematic cross-sectional view of an essential part for explaining a solder ball arrangement pattern in a conventional BGA package.

[Explanation of symbols]

11 ... Package body (land grid array),
12a, 12b ... Ball mounting pad, 13 ... Solder ball, 14 ... Solder paste, 15 ... Semiconductor chip, 16 ...
Ridge portion, 17 ... Wiring pattern, 18 ... Internal wiring.

Claims (3)

[Claims] 1. A ball grid array type package device in which a solder ball for mounting on a printed wiring board is fixed to a land grid array on which a semiconductor chip is mounted. A package device, wherein at least two kinds of pads having different sizes for fixing the solder balls respectively are arranged in a grid on the array. 2. The package device according to claim 1, wherein the pads are formed by alternately arranging wide pads and narrow pads. 3. The pad is the land grid.
2. The package device according to claim 1, wherein a pad having a large area is arranged only at a key portion of the array.