JP2636779B2 - Structure of ball-shaped external connection terminal and method of forming the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection structure for a semiconductor device on which a semiconductor element is mounted, and more particularly to a ball-shaped external connection provided on the semiconductor device for electrically connecting the semiconductor device and a mother board by solder melting. It relates to a terminal connection structure.

[0002]

2. Description of the Related Art A multi-chip module (M) in which one or a plurality of semiconductor elements and electronic components are mounted on a mounting board.
Numerous methods have been proposed as a method of mounting a CM) on a motherboard and electrically connecting them. Among them, as a most common method, a ball-shaped metal projection serving as an external connection terminal is formed on a surface of the MCM to be joined to the motherboard. The ball-shaped metal projections are generally formed of solder, and after the metal projections of the MCM and the connecting portions of the motherboard are aligned and mounted, the metal projections are heated and melted and joined to each other. There is. A ball grid array (BG) in which the metal protrusions are arranged in a grid pattern
Regarding A), the structure and connection method of a conventional BGA will be described with reference to the drawings.

FIG. 10A shows a cross-sectional structure of an external connection terminal of a conventional semiconductor device. This figure shows a general B
4 is a cross-sectional structure of a GA. In such a conventional structure of the BGA, the semiconductor chip 3 is mounted face-up on the first surface (front surface) of the wiring substrate 7 of the MCM, and the semiconductor chip electrode 8 and the bonding pad 2 of the wiring substrate 7 9 are electrically connected. Further, the connection is made from the bonding pad 2 to the through hole 1 by a wiring pattern. Then, through the through hole 1, it is electrically connected to a solder pad 6 for forming an external connection terminal provided at a position remote from the through hole 1 on the second surface (back surface) by a wiring pattern. On this solder pad 6, a solder ball 4 as an external connection terminal is formed. A general method for forming the solder balls 4 on the solder pads 6 is to use a metal mask having an opening of a pattern corresponding to the solder pads 6 and apply cream solder to the solder pads 6 by a printing method.
Supply a fixed amount on top. Thereafter, the cream solder is melted by reflow to form a hemispherical solder ball 4 with surface tension. The connection structure of the ball-like external connection terminals is obtained by such a method. Still another method is to print and supply a predetermined amount of cream solder or high-viscosity flux on the solder pad 6 and then use the tackiness of the cream solder or flux to attach solder balls and then reflow to obtain a height. There is little variation, and a higher structure of the external connection terminal is obtained. As conventional examples of such a structure, "Electronic Materials Issued May, 1994-page 22", "Nikkei Electronics Issued February 14, 1994-page 61", and "USP
-5, 241, 133 ".

FIG. 10 (b) shows a bare chip mounted face-down, and the other parts have the same structure.
In these conventional structures, a solder pad is provided at a position away from the through hole to form a solder ball.
This is because when a solder ball is formed in the through hole part,
This is because the molten solder at the time of reflow is sucked into the through holes, and the formed solder balls vary in height. However, this causes a problem that the wiring length of the pattern becomes longer, and the degree of freedom of the pattern drawing is reduced, and the design is restricted.

[0005] In addition, there is a structure described in Japanese Utility Model Laid-Open No. 2-102738 as a structure in which an external connection terminal is provided immediately below a through hole. FIG. 11 shows a cross-sectional structure of this example. This is one in which a metal pin 12 protruding from the lower surface side of the circuit board is planted in a through hole forming an external connection terminal, and a solder ball is formed so as to wrap the protruding portion of the metal pin 12. . However, when a solder ball having such a structure is formed, a specially-designed metal pin corresponding to the diameter of the through hole is required, and there is no versatility.
Further, a dedicated facility for quickly and accurately implanting the metal pin in the through hole is required, which increases the cost.

[0006]

SUMMARY OF THE INVENTION In order to meet the demand for high performance, high functionality and further miniaturization of a device using a semiconductor element, an MCM is used as a method of high-density mounting on a motherboard.
However, in the conventional MCM, as described in the conventional example, it is necessary to provide a solder pad for forming a BGA ball at a distance from the through hole. Therefore, there is a problem that the wiring length becomes longer and it is difficult to further improve the performance. Further, there is a problem that expensive equipment having high-precision and high-speed functions is required to form a BGA ball directly under the through hole.

[0007]

The structure of the ball-shaped external connection terminal according to the present invention is a ball-shaped external connection terminal of a semiconductor device in which one or a plurality of semiconductor elements or electronic components are mounted on a printed wiring board. in structure, the flop
Formed on a printed wiring board and electrically connected to the semiconductor element.
The connected through-hole and the through-hole
The semiconductor device is mounted directly on the motherboard.
Ball-shaped external connection terminals for mounting and electrical connection
Comprising a part or all of the inside of the through-hole,
It is sealed with cream solder or resin
It is. Further, the formation of the ball-shaped external connection terminal of the present invention
The method consists of one or more semiconductors on a printed circuit board.
Elements or semiconductor devices with electronic components
The semiconductor element formed on the printed circuit board and
Ball directly under the through through hole
A method of forming an external connection terminal, comprising:
Resin or cream solder as sealing material inside the hole
Supplying, and utilizing the adhesiveness of the encapsulant
A terminal is attached immediately below the through hole and mounted.
And the step of performing.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. Embodiment 1 FIG. 1A shows an MC according to a first embodiment.
It is sectional drawing of M. This figure shows a state before the reflow when the solder ball 14 is mounted. In order to obtain this structure, a certain amount of resin of the sealing material 13 is supplied by a printing method or a dispenser to the through hole of the entire wiring board 7 of the MCM or the through hole 1 forming a ball-shaped external connection terminal. The solder balls 14 are attached and mounted using the adhesiveness of the material 13. There are various methods for attaching and mounting a solder ball at a predetermined location, but a simple example is a method using a transfer plate jig. The transfer plate is provided with a hemispherical or cylindrical hole at a predetermined position where the solder ball can enter, and the solder ball is dropped into this hole. Then, after removing the excess solder balls, the wiring board 7 is put on from above, and the wiring board 7 and the transfer plate jig are turned over at the same time without dislocation. After that, the transfer plate jig is inverted at the same time so as not to be displaced. After that, the solder ball is mounted at a predetermined position by removing the transfer plate jig. The substrate on which the solder balls are mounted by such a method is reflowed (230 ° C. to 2 ° C.
40.degree. C.) to obtain the structure of the solder balls 16 connected to the lands 15 in FIG. The MCM having the ball-shaped external connection terminals thus obtained is mounted on the motherboard 18 and reflowed to obtain a structure connected to the pad 19 in FIG. With this connection structure, MCM
The wiring between the semiconductor element 3 mounted on the first surface and the motherboard 18 can be shortened, and electric signals can be transmitted efficiently. Embodiment 2 FIG. 1B shows a second embodiment, and FIG.
This is a state before reflow, as in the state of (b). This is almost the same as the first embodiment, and the differences will be described here. In this structure, after a certain amount of resin of the sealing material 13 is supplied to a through hole of the entire wiring board of the MCM or a through hole 1 forming a ball-shaped external connection terminal by a printing method or a dispenser, the resin is heated to 120 to 150 ° C.
And curing for 2 hours and 3 hours. Thereafter, a certain amount of the flux 11 is supplied to the land 15 on the outer periphery of the through hole by a printing method or a dispenser. Then, by utilizing the adhesiveness of the flux 11, the solder ball 14 is attached and mounted, and the state shown in FIG. 1 (b) is obtained.
2 similar to the embodiment of FIG. Although the flux is used as an example here, a similar structure can be obtained by using a cream solder. According to this embodiment, a more reliable connection structure having better solder wettability than that of the first embodiment was obtained. Third Embodiment FIG. 4 is a sectional view of a third embodiment. The feature of this structure is that high melting point solder balls 2
0 is used. As the high melting point solder ball, for example, Pb65 / Sn35 solder (melting point 248)
C.) and Pb70 / Sn30 solder (melting point: 258 ° C.) having a higher melting point than eutectic solder (melting point: 183 ° C.) used for soldering general electronic components.
As the sealing material 13, a conductive resin or cream solder is used. As a method of obtaining the structure of this embodiment, a fixed amount of the sealing material 13 is supplied to the through hole 1 in the same manner as in the first and second embodiments, and the high melting point solder balls 20 are attached and mounted on the supplied sealing material 13. . Thereafter, when a conductive resin is used, the resin is cured at a predetermined temperature. In the case of the cream solder, the MC of the structure in FIG.
M was obtained. FIG. 5 is a sectional view showing a state where the MCM is mounted on the motherboard 18 and connected. In this example, the external connection terminal could be formed as it was without melting the solder ball during reflow, and a height having less variation in height was obtained. As a result, components such as semiconductor elements could be mounted on the surface of the MCM on which the external connection terminals were to be formed. Embodiment 4 FIG. 6 shows a fourth embodiment. After the through hole 1 is sealed with a resin 23 and cured, cream solder is supplied onto the land 15 by a printing method. Then the third
The same high-melting-point solder balls as those of Example 1 were attached and reflowed, and external connection terminals were formed. In this embodiment, it was possible to reduce the cost by using a general resin instead of a conductive resin as the sealing material for the through hole. Fifth Embodiment FIG. 7A shows a fifth embodiment. This embodiment is characterized in that a ball having a metal core plated with solder is used. The solder plating ball has, for example, a metal core made of a copper ball and has its surface plated with solder. The connection structure of this embodiment is such that the flux 11 is applied to the entire surface of the wiring board 7 on which the external connection terminals are formed, or only to the pad 15 of the through hole 1, and the solder plated ball is attached and reflowed to reflow the ball. The solder plating on the surface is melted and connected to the through hole 1 and the pad 15 to form an external connection terminal.
The height of the external connection terminal has little variation, and is approximately the height of a copper ball which is a metal core. This state is shown in FIG.
(B). FIG. 8 shows a state in which the MCM is mounted on a motherboard and connected. This embodiment is inexpensive because no resin or cream solder is used, and is excellent in productivity because it involves fewer steps. Sixth Embodiment FIG. 9A is an embodiment of the MCM of the external connection terminal 25 formed in the first to fifth embodiments and the external connection terminal 26 partially formed by the conventional technique. . FIG. 9B is almost the same, except that the wiring board 7 is formed by a method called build-up in a portion where the external connection terminal is formed in the related art. . According to this method, it is possible to form a solder pad 6 having a depressed shape, and in this embodiment, an external connection terminal 26 is formed by a conventional technique. By employing such a structure in combination with the conventional technology, more external connection terminals could be provided.

[0009]

As described above, according to the present invention, the ball-shaped external connection terminals are provided immediately below the through holes, whereby the degree of freedom of the wiring pattern is increased, and the wiring length can be shortened. Therefore, the signal transmission efficiency was improved. Further, a ball-shaped external connection terminal could be easily and inexpensively formed without using expensive equipment.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are cross-sectional views showing first and second embodiments of the present invention.

FIG. 2 is a sectional view showing an example of use of the present invention.

FIG. 3 is a sectional view showing an example of use of the present invention.

FIG. 4 is a sectional view showing a third embodiment of the present invention.

FIG. 5 is a sectional view showing a usage example of the present invention.

FIG. 6 is a sectional view showing a fourth embodiment of the present invention.

FIG. 7 is a sectional view showing a fifth embodiment of the present invention.

FIG. 8 is a sectional view showing an example of use of the present invention.

FIGS. 9A and 9B are cross-sectional views showing sixth and seventh embodiments of the present invention.

FIGS. 10A and 10B are cross-sectional views showing first and second conventional examples.

FIG. 11 is a sectional view showing a third conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Through hole 2 Bonding pad 3 LSI chip 4 Solder ball 5 Solder resist 6 Solder pad 7 Wiring board 8 LSI electrode 9 Wire 10 Bump 11 Flux 12 Metal pin 13 Sealing material 14 Solder ball 15 Land 16 Solder ball 17 Connection part 18 Motherboard 19 Pad 20 High melting point solder ball 21 Solder plating ball 22 Connection part 23 Resin 24 Cream solder 25 Terminal for external connection 26 Terminal for external connection

Claims (8)

(57) [Claims] In a structure of a ball-shaped external connection terminal of a semiconductor device having one or a plurality of semiconductor elements or electronic components mounted thereon on a printed wiring board, the semiconductor element is formed on the printed wiring board, and is electrically connected to the semiconductor element.
A through-hole that is pneumatically connected, and formed immediately below the through-hole;
Ball shape for mounting on the motherboard and electrically connecting
External connection terminals, and a part or all of the inside of the through-hole is cream.
A structure of a ball-shaped external connection terminal, which is sealed with solder or resin . 2. The structure of a ball-shaped external connection terminal according to claim 1 , wherein said resin is a conductive resin . 3. The ball-shaped terminal for external connection has a high melting point.
2. The structure of the ball-shaped external connection terminal according to claim 1, which is formed by solder . 4. The ball terminal for external connection is a metal core.
2. The structure of a ball-shaped external connection terminal according to claim 1, wherein the ball-shaped external connection terminal is a ball having a solder plated surface. 5. A printed circuit board comprising one or a plurality of
Semiconductors or semiconductors with electronic components mounted on them
The semiconductor element formed on the printed circuit board of the device;
Directly below the through-hole electrically connected to the
A method of forming a metal external connection terminal, wherein a resin or a resin is used as a sealing material inside the through-hole.
Supplying a solder ball, and utilizing the adhesiveness of the sealing material to pass the ball-shaped terminal through the through-hole.
Attaching and mounting directly below the through hole
A method of forming a ball-shaped external connection terminal, characterized in that: 6. The ball-shaped terminal, wherein the ball-shaped terminal is
High melting point that does not melt when the mounted board is reflowed
6. The ball-shaped outside according to claim 5, which is formed by solder.
The method of forming the connection terminal. 7. One or a plurality of printed circuit boards
Semiconductor element Oh semiconductor Rui is equipped with them and the electronic component
The semiconductor element formed on the printed circuit board of the device;
Directly below the through-hole electrically connected to the
Forming a sealing material inside the through-hole, and supplying the sealing material to the inside of the through-hole.
Curing and supplying flux to the land on the outer periphery of the through-hole.
Supplying the ball-like terminal by utilizing the adhesiveness of the flux.
Step of attaching and mounting directly under the through hole
Method of forming ball-shaped external connection terminal characterized by including
Law. 8. A substrate on which the ball-shaped terminals are mounted is removed.
8. The ball-shaped exterior of claim 7 including the step of flowing.
How to form connection terminals.