JPH11251726A - Method for mounting grid array type semiconductor package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a terminal from rising and causing short-circuit and also to correctly align a package. SOLUTION: With at least a package 1 where a recessed part 11 is provided at least at three points, a printed board 3 where a recessed part 13 is provided at a position corresponding to each recessed part 11, and at least three balls 10 used, the ball 10 is inserted in the recessed part 13 of the printed board 3, the package is so placed on the printed board that each recessed part 11 is positioned on the ball 10, and the package is applied with a load F when the printed board is heated. Here, with the melting point of the ball 10 higher than the solder used for soldering, the size of the ball 10, the recessed part 11, and the recessed part 13 is so adjusted that, before the printed board is heated, a terminal 2 contacts a land 4 while each ball 10 detaches from the recessed part 11 of the package, and, after heating, the solder is collapsed under the load F for each ball 10 to contact the recessed part 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for mounting a grid array type semiconductor package on a printed circuit board.

[0002]

2. Description of the Related Art Grid array type semiconductor packages are:
Terminals are arranged in a grid shape (lattice shape) on the back surface of the package, and BGA packages, LGA packages, and PGA packages are mainly used. The outline is shown below. (1) BGA package: As shown in FIG.
In the GA package 101, ball-shaped terminals 102 are arranged in a grid portion (a portion of a grid point). JP-A-8-3
As disclosed in US Patent No. 16628, generally,
Each ball-shaped terminal 102 of the BGA package 101 is soldered to a flat land 104 of a printed circuit board 103. Reference numeral 112 denotes solder. Normally, solder balls are used for the ball terminals 102. (2) LGA package: As shown in FIG.
In the GA package 105, flat land-like terminals 106 are arranged in a grid portion, and each land-like terminal 106 is soldered to a flat land 104 on a printed circuit board 103. (3) PGA package: As shown in FIG.
In the GA package 107, the pin-shaped terminal 1
08 are arranged, and each pin-shaped terminal 108 is connected to the printed circuit board 3.
Are inserted into the through holes 109 and soldered to the lands 110 around the through holes 109. The diameter of the through-hole 109 is much larger than that of the pin-shaped terminal 108.

When the BGA package 101 or the LGA package 105 is mounted on the printed circuit board 103, the terminals 102 and 106 and the lands 104 are hidden behind the package, so that the mounting positions of the terminals 102 and 106 and the corresponding lands 104 are determined. It is not easy to confirm and correct the deviation.

In the case of the PGA package 107, the pin-shaped terminals 108 can be seen on the back surface of the substrate through the through-holes 109, so that the displacement of the mounting position can be confirmed. However, the diameter of the through-holes 109 is much larger than that of the pin-shaped terminals 108. Therefore, it is not easy to correct the mounting position so that the pin-shaped terminal 108 is disposed at the center of the through hole 109.

Japanese Patent Application Laid-Open No. Hei 9-162527 discloses a BG
Confirmation of displacement of mounting position when mounting A package, and
Techniques that can make that correction are described. In this position control technique, as shown in FIG. 5, a concave portion 111 is formed in advance on a land 104 of a printed circuit board 103 to which a BGA package 101 is to be soldered.
1, the ball-shaped terminals 102 of the BGA package 101 are put in and soldered.

On the other hand, Japanese Patent Application Laid-Open No. Hei 8-316628 discloses a technique for controlling the height so that terminals do not float when a BGA package is mounted. In this height control technique, although not shown, the spacing between the BGA package and the printed circuit board is maintained by solder balls having a higher melting point than the solder balls of the BGA package.

However, the position control technology described in Japanese Patent Application Laid-Open No. 9-162527 and the height control technology described in Japanese Patent Application Laid-Open No. 8-316628 can be implemented only in separate steps.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a mounting method of a grid array type semiconductor package which can prevent floating and short-circuit of terminals by performing height control and can also perform alignment at the same time. To provide.

[0009]

According to a first aspect of the present invention, there is provided a method of mounting a grid array type semiconductor package, comprising: a grid array type semiconductor package having at least three concave portions except for at least three other portions; , A package), using a printed board provided with recesses in at least three positions corresponding to the recesses of the package, and at least three spheres, and using each sphere in each recess of the printed board. Inserting, placing the package on the printed circuit board so that each concave portion of the package is located on each of these spheres, applying a load to the package on the printed circuit board when heating and soldering the printed circuit board, Each of the spheres has a higher melting point than the solder used to solder the terminals of the package and the lands of the printed circuit board. Before heating the printed circuit board, the size of each of the recessed portions of the printed circuit board and the size of each of the recessed portions of the printed circuit board are such that the terminals of the package are in contact with the lands of the printed circuit board, but each sphere is separated from each of the recessed portions of the package, After heating, the solder is crushed by a load and each sphere is adjusted so as to be in contact with each concave portion of the package.

According to a second aspect of the present invention, there is provided the grid array type semiconductor package mounting method according to the first aspect of the present invention, wherein a load is applied to the package by pressing the plurality of rollers on the lower surface thereof with a pressing tool. It is characterized by the following.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, FIGS. 1 to 3 and FIGS.
A method for mounting a grid array type semiconductor package according to an embodiment of the present invention will be described with reference to FIG. FIG.
Shows an example of a mounting method of a BGA package, FIG. 2 shows a principle of height control and position control, and FIG. 3 shows an example of a pressing tool. FIG. 6 shows an example of a method of forming a recess on the printed circuit board side, and FIG. 7 shows an example of a method of forming a recess on the grid array type semiconductor package.

(Embodiment 1) An example of a mounting method of a BGA package will be described with reference to FIG. Here, BGA
In addition to the package 1 and the printed circuit board 3 on which the BGA package 1 is mounted, an appropriate number of high melting point solder balls 10 having a higher melting point than the solder ball terminals 2 of the BGA package 1 are prepared. The high melting point solder ball 10 is a sphere having a uniform outer diameter and is different from the BGA package 1.

As shown in FIG. 1B, solder ball terminals 2 are arranged on each grid portion on the back surface of the BGA package 1, and four locations, for example, 4
Outside the corner grid portion, a concave portion 11 large enough to receive a part of the high melting point solder ball 10 is formed. This recess 1
The shape of 1 is spherical (bowl-shaped) or conical (tapered). A spherical or conical land 12 is formed inside the recess 11.

As shown in FIG. 1B, a flat land 4 is formed on the printed board 3 at a position corresponding to each ball-shaped terminal 2 of the BGA package 1. Are formed at four positions corresponding to the recesses 13 in such a size that a portion of the high-melting-point solder ball 10 can be accommodated. In the printed circuit board 3 of this example, concave portions 13 are formed at four corners of a region where the BGA package 1 is mounted. The shape of the recess 13 is also spherical (bowl-shaped) or conical (tapered). Hung from the inside of the recess 13 to the periphery,
A spherical or conical land 14 with a flange is formed.

Before mounting the BGA package 1 on the printed circuit board 3, first, as shown in FIG.
The high melting point solder balls 10 are inserted into the recesses 13 of the printed circuit board 3.

Next, as shown in FIG. 1B, the BGA package 1 is mounted on the printed circuit board 3 such that each recess 11 of the BGA package 1 just covers each solder ball 10 on the printed circuit board 3.

At this time, cream solder or flux is usually applied to the printed circuit board 3 before mounting the BGA package 1.
Are applied to the lands 4 and 14, and after the cream solder or flux is applied, the high melting point solder ball 10 is inserted into the concave portion 12 so that the cream solder or flux becomes an adhesive and the high melting point solder ball 10 is released. Completely block. Even when an adhesive is not used, each high-melting-point solder ball 10 is hard to separate from the concave portion 13 of the printed circuit board 3 even if a slight vibration or inclination occurs.

The printed circuit board 3 on which the BGA package 1 is mounted is placed in, for example, a reflow furnace (not shown), and a load is applied from above the BGA package 1 by a pressing tool 15 or the like as shown in FIG. While adding F, the printed circuit board 3 is heated and soldered.

Here, the high melting point solder ball 10, the concave portion 11 of the BGA package 1, and the concave portion 13 of the printed circuit board 3
Are set as follows (1) to (3). (1) The melting point of the high melting point solder ball 10 is, as described above,
It is higher than the ball-shaped terminals (solder balls) 2 of the BGA package 1. (2) Before heating the printed circuit board 3 in a reflow furnace or a repair jig, etc., the ball-shaped terminals 2 of the BGA package 1
Are in contact with the lands 4 of the printed circuit board 3, but the high melting point solder balls 10, the recesses 11 of the BGA package 1 and the recesses 13 of the printed circuit board 3 are separated from the respective recesses 11 of the BGA package 1. The size of has been adjusted. (3) After the printed board 3 is heated in a reflow furnace or a repair jig, the ball-shaped terminal (solder ball) 2 is crushed by the load F, and the high-melting-point solder ball 10 is placed in each recess 11 of the BGA package 1. High melting point solder ball 1
The size of the concave portion 11 of the BGA package 1 and the concave portion 13 of the printed circuit board 3 are adjusted.

Therefore, if the BGA package 1 is simply placed on the printed circuit board 3, there is a possibility that a portion that is not mounted may occur due to a variation in the size of the terminal 2. However, when the printed circuit board 3 is heated in a reflow furnace or the like, When a load is applied to the package 1, the ball-shaped terminals 2 are crushed by heat and load, and the concave portions 21 of the BGA package 1 and the high-melting-point solder balls 10 come into contact with each other. 2 is prevented from floating.

If the load is applied too much, the solder of the terminals 2 may be excessively crushed and protrude, and the terminals 2 may be short-circuited. The collapse, and thus the height, stops at the height of the high melting point solder ball 10. That is, the BGA package 1 is formed by the high melting point solder balls 10.
, That is, the space between the BGA package 1 and the printed circuit board 3 to prevent the solder from protruding and short-circuiting.

Further, even if the position of the BGA package 1 is slightly shifted when the BGA package 1 is mounted on the printed circuit board 3, as shown by an arrow 16 in FIG.
The concave portion 11 is guided by the high melting point solder ball 10 and is positioned at an optimum position.

(Embodiment 2) Referring to FIG.
An example will be described. The pusher 15 shown in FIG. 3 includes a plurality of spherical rollers 17 on a lower surface in contact with the BGA package 1.
It is provided.

When the load 17 is applied by pressing the roller 17 against the upper surface of the BGA package 1, the BGA package 1 can be easily moved to an optimum position.

As described above, by forming the concave portion 11 on the BGA package 1 side and the concave portion 13 on the printed board 3 side into a spherical shape or a conical shape, the positioning of the BGA package 1 and the printed board 3 by the high melting point solder balls 10 is extremely possible. Done exactly.

Only the concave portion on the BGA package 1 side is spherical, and only the concave portion on the printed circuit board 3 side is conical.
Only the concave portions on the BGA package 1 side may be conical and only the concave portions on the printed circuit board 3 side may be spherical. Further, the shape of each of the concave portions 11, 13 is not necessarily required to be spherical or conical, and even if other shapes such as cylindrical are used,
The intended purpose of performing positioning easily and easily can be achieved.

In the above embodiment, four recesses 11 of the BGA package 1 are formed. However, considering that a load F is stably applied to the BGA package 1, three or more recesses 11 may be used.

Although the recesses 11 are formed at corners other than the grid portion of the BGA package 1, the terminals of the grid portions at the four corners of the grid array type semiconductor package usually have the internal I terminals.
In many cases, non-contact (non-contact) with the C chip is used.
May be formed. Further, since the center of the back surface of the package is usually empty without any space, the recess 11 may be formed here. As described above, when the concave portion 11 is formed by using the grid portion at the corner or the central portion of the back surface of the package, the degree of freedom of the concave portion forming place is increased.

In any case, since electrical connection is not required between the concave portion 11 of the BGA package 1 and the concave portion 13 of the printed circuit board 3, if the melting point is higher than that of the ball-shaped terminal 2, in addition to the high melting point solder ball 10, Any sphere can be used.

Further, in the above embodiment, the BGA package 1
Although the mounting method has been described, the same can be applied to the LGA package.

Here, the spherical or conical recess 11,
An example of a method for forming the semiconductor device 13 will be described with reference to FIGS.

FIG. 6 shows an example of a method for forming a spherical concave portion or a conical concave portion on the printed circuit board 3. First, FIG.
As shown in FIG. 2A, a solder resist 20 is formed on the printed circuit board 3 while leaving the lands 4, and a copper foil 21
Then, an etching resist 23 is formed on the copper foil 21 by making a hole 22 above the land 4 where a spherical concave portion or a conical concave portion is to be formed. Next, FIG.
As shown in (b), the whole is put into an etching bath 24, and the copper foil other than where the etching resist 23 is mounted is corroded and removed. Next, as shown in FIG. 6C, the etching resist 23 is removed, and a solder resist 25 is formed while leaving the land and the spherical or conical concave portion 13. Thereby, the spherical or conical recess 13 is formed.
The printed circuit board 3 having the following is obtained. Since the copper foil 21 is corroded in a tapered shape by the etching, a conical concave portion is formed by etching until the copper foil 21 passes through the copper foil 21 and reaches the land 4.
By stopping the etching in the middle of the process, a substantially spherical concave portion is formed. At the same time, the spherical or conical recess 13
A flanged spherical or conical land 14 is formed inside and around.

FIG. 7 shows an example of a method of forming a spherical or conical recess in the BGA package 1 or the like. First, a spherical or conical concave portion 11 and a flanged spherical or conical land 12 inside and around the concave portion 11 are formed on a printed circuit board 26 of a semiconductor package by a method similar to that shown in FIG. Next, as shown in FIG. 7A, the bare chip 27 of an IC (semiconductor integrated circuit) is mounted on the printed board 36, and the printed board 26 and the electrodes of the bare chip 27 are connected by bonding wires 28. Next, as shown in FIG. 7B, the printed circuit board 26 having the bare chip 27 is put into the package molding die 29, and the resin injection port 30 of the package molding die 29 is used.
As shown in (c), the resin 31 is injected into the bare chip 27 side. Then, as shown in FIG. 7D, the printed board 26 having the bare chip 27 is
Take out. Thereby, the spherical or conical concave portion 1 is formed.
1 and the like. A flanged spherical or conical land 12 is formed inside and around the spherical concave or conical concave 11.

[0034]

According to the first aspect of the present invention, it is possible to prevent the floating and short-circuiting of the terminals and to align the grid array type semiconductor package.

According to the second aspect of the present invention, the grid array type semiconductor package can be easily moved to an optimum position by the roller of the pressing tool.

[Brief description of the drawings]

FIG. 1 is a view showing an example of a mounting method of a BGA package according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the principle of height control and position control.

FIG. 3 is a diagram showing an example of a pressing tool.

FIG. 4 shows BGA packages, LGA packages, and PGs as main components of a grid array type semiconductor package.
The figure which shows A package.

FIG. 5 is a diagram showing a mounting method of a conventional BGA package.

FIG. 6 is a diagram illustrating an example of a method of forming a printed board side recess.

FIG. 7 is a diagram showing an example of a method of forming a concave portion on the side of a grid array type semiconductor package.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 BGA package 2 Ball-shaped terminal 3 Printed board 4 Flat land 10 High-melting-point solder ball 11, 13 recess 12 Land 14 Land 15 Pusher 16 Arrow 17 Roller

Claims (2)

[Claims] 1. A grid array type semiconductor package (hereinafter referred to as a package) having at least three concave portions, a printed board having at least three concave portions corresponding to each of the concave portions of the package, Using at least three spheres, inserting each sphere into each recess of the printed circuit board, mounting the package on the printed circuit board such that each recess of the package is positioned on each of these spheres, Applying a load to the package on the printed board when performing soldering by heating, each of the spheres has a higher melting point than the solder used for soldering the terminals of the package and the lands of the printed board, and each of the spheres, The size of each recess of the package and each recess of the printed board is such that the terminals of the package are It is adjusted so that the spheres are in contact with the lands of the plate, but each sphere separates from each recess of the package, and after heating the printed circuit board, the solder is crushed by the load and each sphere comes into contact with each recess of the package. Characteristic mounting method of grid array type semiconductor package. 2. The method according to claim 1, wherein a load is applied to the package by applying a load to the package by a pusher having a plurality of rollers on a lower surface.