JPH0799385A - Solder ball, manufacture thereof and connection structure - Google Patents

Abstract

PURPOSE:To connect reliably connection terminals opposing to each other without causing a short-circuit between the adjacent connection terminals by a method wherein a solder layer of a melting temperature lower than that of a metal nucleus is applied on the surface of the metal nucleus. CONSTITUTION:A. solder layer 20 is applied on the surface of a metal nucleus 10 at a temperature lower than the melting temperature of the metal nucleus 10 and a solder ball 100 is formed. In the case where the ball 100 is connected between connection terminals 41, if the layer 20 is melten and the ball 100 is connected between the terminals 41 through this molten solder layer 20, a gap between the terminals 41 can be reliably secured by the nucleus 10. Moreover, the whole ball 10 can be prevented from crushing by the nucleus 10 interposed between the terminals 41 and the adjacent terminals 41 are not short- circuited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder ball, a method for manufacturing the same, and a connection structure, and more specifically, a solder ball for electrically connecting connection terminals of a printed wiring board, electronic parts, etc., and a method for manufacturing the same. And a connection structure for electrically connecting the connection terminals with solder balls.

[0002]

2. Description of the Related Art Conventionally, for example, when a plurality of printed wiring boards are stacked, the connecting terminals of each printed wiring board are electrically connected, or when the electronic parts are mounted on the printed wiring board, the connecting terminals of the printed wiring board are connected. There is a solder ball as a means for electrically connecting the connection terminal of the electronic component and the connection terminal of the electronic component. Here, the conventional solder ball has, for example, a composition of S.
So-called 6/4 solder with n / Pb = 6/4, composition is Sn / P
So-called 9/1 solder with b = 9/1, composition is Sn / Pb = 1
It was formed of a single composition solder such as a so-called 1/9 solder of / 9.

[0003]

However, in the conventional solder balls, since the solder balls for connecting the connection terminals are formed by the solder having a single composition,
There is a problem that the entire solder ball may be melted and crushed, and the crushed solder balls may contact each other and short-circuit in the adjacent connection terminal. In particular, when a plurality of connection terminals are finely formed, a short circuit is likely to occur due to the collapse of the solder balls.

Further, when a plurality of printed wiring boards are stacked or when electronic components are mounted on the printed wiring board, a gap is provided between the stacked printed wiring boards or between the printed wiring board and the electronic components. In some cases, a gap may be provided to efficiently release heat generated from the electronic component or to easily remove dust and the like on the surface of the printed wiring board. However,
In the case of the conventional solder balls, there are cases where the entire solder balls are crushed by melting and the aforementioned gap cannot be formed.

Each of the present inventions has been made to solve such a problem. An object of the invention is, first, in the invention of claim 1 that the adjacent connection terminals are not short-circuited. An object of the present invention is to provide a solder ball having a simple structure that can reliably connect the opposing connection terminals and can reliably secure a gap between the opposing connection terminals.

Next, in a second aspect of the invention, a solder ball manufacturing method capable of easily and reliably manufacturing the high-quality solder ball according to the first aspect of the invention is described. Is to provide.

Finally, in the third aspect of the invention, there is provided a connection structure capable of reliably ensuring a gap between opposing connection terminals without causing a short circuit in the adjacent connection terminals.
It is to provide by a simple structure.

[0008]

Means for Solving the Problems In order to solve the above problems, the means adopted by the present invention will be described with reference to the reference numerals used in the drawings. 1
The solder layer 2 having a lower melting temperature than the metal core 10 on the surface of
Solder ball 10 characterized by being coated with 0
It is 0 ".

Next, the invention of claim 2 is a method for manufacturing a solder ball 100 according to claim 1, which includes the following steps: (1) A step of putting a metal ball 10a serving as the metal nucleus 10 and a solder ball 20a serving as the solder layer 20 formed of a solder having a melting temperature lower than that of the metal ball 10a into a container 30; (2) melting the metal ball 10a The solder ball 20a is melted at a temperature lower than the temperature to melt the solder on the surface of the metal ball 10a, and the solder layer 2 is formed on the surface of the metal core 10.
Forming a solder ball 100 covered with 0. "
Is.

[0010] Finally, the invention of claim 3 is a "connection structure for electrically connecting the connection terminals 41 facing each other by the solder balls 100, and the metal core 10 interposed between the connection terminals 41, The melting temperature is lower than that of the metal core 10 and the surface of the metal core 10 is covered and the connecting terminals 4
1 and a solder layer 20 welded to the No. 1 connection structure.

[0011]

The solder ball 100, the method for manufacturing the same and the connection structure according to the present invention thus configured are
It works as follows.

First, in the solder ball 100 according to the invention of claim 1, the surface of the metal core 10 is coated with the solder layer 20, and the solder layer 20 has a melting temperature lower than that of the metal core 10. Is. Therefore, when the solder ball 100 is melted to connect the connection terminals 41, the solder layer 20 is melted at a temperature lower than the melting temperature of the metal core 10, and the melted solder layer 20 connects the connection terminals 41. Then, the metal core 10 is surely interposed between the connection terminals 41. Therefore, a gap is reliably secured by the metal core 10 between the opposing connection terminals 41. Further, the metal core 10 interposed between the connection terminals 41
Since the crushing of the entire solder ball 100 is prevented by the crushed solder ball 100, the adjacent connection terminals 41 are not short-circuited.

Next, in the method for manufacturing the solder ball 100 according to the second aspect of the present invention, the metal ball 10 which becomes the metal core 10 is formed.
a and a solder ball 20a formed of solder having a melting temperature lower than that of the metal ball 10a are placed in a container 30, and the solder ball 20a is melted at a temperature lower than the melting temperature of the metal ball 10a to be soldered on the surface of the metal ball 10. The solder balls 100 according to the above-mentioned invention of claim 1 are formed by welding.
According to such a method, the metal nuclei 10 are surely left,
The surface of the metal core 10 is surely covered with the solder layer 20, so that the high quality solder ball 100 can be easily and surely manufactured.

Finally, the connection structure according to the invention of claim 3 is the solder ball 100 according to the invention of claim 1 described above.
The connection terminals 41 facing each other are electrically connected to each other, the metal core 10 is interposed between the connection terminals 41 facing each other, and the solder layer 20 is welded to each connection terminal 41. Therefore, the gap formed by the metal core 10 is reliably secured between the opposing connection terminals 41. In addition, the metal core 10 causes the solder ball 100
Since the crushing of the entire solder ball 100 is prevented, the crushing of the entire solder ball 100 does not short-circuit the adjacent connection terminal 41. Further, since the solder layer 20 is welded to each connection terminal 41, the connection layer 41 is electrically and reliably connected, and the connection reliability between the connection terminals 41 is not deteriorated.

[0015]

Embodiments of the solder ball 100, the method of manufacturing the same and the connection structure according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the solder ball 100 according to the invention of claim 1. In this solder ball 100, a solder ball formed of 9/1 solder having a melting temperature of about 215 ° C. is used as a metal core 10, and the surface of the metal core 10 is formed of 6/4 solder having a melting temperature of about 185 ° C. The coated solder layer 20 is coated. Not limited to this embodiment, the metal core 10 may be formed of a metal such as gold (melting temperature of about 1064 ° C.) or silver (melting temperature of about 962 ° C.) having excellent conductivity and higher melting temperature than solder.

When manufacturing such a solder ball 100, the surface of the metal core 10 may be coated with the solder layer 20 by electrolytic plating or electroless plating. When the solder layer 20 is formed by the above method, not only a long-time plating process is required to obtain the solder layer 20 having a sufficient thickness, but also the solder layer 20 varies and a high quality solder ball 100 is formed. Have difficulty. In addition, complicated processes such as a pretreatment process for plating are required. Therefore, it is preferable to manufacture the solder ball 100 according to the second aspect of the invention.

Next, an embodiment of the method for manufacturing the solder ball 100 according to the invention of claim 2 will be described with reference to the process diagram shown in FIG.

First, a container 30 having a hole with a diameter of 0.9 mm and a depth of 1.5 mm, the surface temperature of which is controlled to 183 ± 2 ° C., is formed with 9/1 solder and has a diameter of 0.6 mm.
The metal ball 10a and the solder ball 20a formed by 6/4 solder are put in (a). In addition, the inner surface of the container 30 is subjected to Teflon processing, chrome plating processing, or the like. Therefore, the inner surface of the container 30 has poor solder wettability, and the solder balls 100 are difficult to weld.

Next, the surface temperature of the container 30 is 200 ± 2 ° C.
To melt the solder balls 20a (b). Here, the time for which the surface temperature of the container 30 is 183 ° C. or higher is 1 minute. Then, the solder of the solder ball 20a is welded to the surface of the metal ball 10a, and the surface of the metal core 10 is covered with the solder layer 20.
00 is formed (c).

If the surface temperature of the container 30 is 195 ° C. or lower, the solder balls 20a will not be completely melted, and
If the temperature is 10 ° C or higher, the metal balls 10a are also melted and mixed with each other, so that the surface temperature of the container 30 is 195 to 195.
It is preferable to heat to 210 ° C. Further, when the surface temperature of the container 30 is 200 ° C., the solder balls 20 a are completely melted, and at 205 ° C., the surface of the metal balls 10 a starts to be melted, so that the surface temperature of the container 30 is 200 to 205.
It is particularly preferable to heat so that the temperature becomes ℃.

Further, in this embodiment, an example in which the individual solder balls 100 are formed in the container 30 is shown, but the present invention is not limited to this, and the solder balls 100 can be directly connected to the connection terminals 41 of the printed wiring board 40 or the like. May be formed. In this case, for example, as shown in FIG. 3, the container 30 is placed on the printed wiring board 40 or the like so that the connection terminals 41 are exposed, and the metal balls 10a and the solder balls 20 are placed in the container 30.
and (a), and the solder ball 20a is melted at a melting temperature lower than that of the metal ball 10a (b), and the connection terminal 41
Solder ball 100 in which a part of the solder layer 20 is welded
May be formed.

Next, FIG. 4 shows an embodiment of a connection structure according to the invention of claim 3. In this connection structure, when a plurality of printed wiring boards 40 are stacked, the connection terminals 41 facing each other of the printed wiring boards 40 are connected by the solder balls 100. In this connection structure,
The metal core 10 is interposed between the connecting terminals 41 facing each other, and the surface of the metal core 10 is covered with the solder layer 20.
Are welded to the upper connection terminal 41 and the lower connection terminal 41, respectively. The metal core 10 reliably secures a gap between the connection terminals 41, and the solder layer 20 electrically reliably connects the connection terminals 41. The connection terminal 4 of the printed wiring board 40 is not limited to the case of stacking a plurality of printed wiring boards 40 as in the present embodiment, but may be, for example, when an electronic component is mounted on the printed wiring board 40.
1 may be connected to the connection terminal 41 of the electronic component.

[0024]

As described in detail above, first, the solder ball according to the invention of claim 1 has a surface of a metal core coated with a solder layer having a melting temperature lower than that of the metal core. When connecting the two, it is possible to prevent the entire solder ball from being crushed due to melting.

Next, in the invention of claim 2, a metal ball and a solder ball having a melting temperature lower than that of the metal ball are placed in a container, and the solder ball is melted at a temperature lower than the melting temperature of the metal ball to form a metal core. Is a method for manufacturing a solder ball according to the invention of claim 1 in which the surface of the metal core is coated with a solder layer, and the metal core can be surely left by a simple method, and the surface of the metal core can be reliably coated with the solder layer. It was done like this.

Finally, the connection structure according to the invention of claim 3 comprises a metal core interposed between the opposing connection terminals, and a solder layer coated on the surface of the metal core and welded to each connection terminal. The metal core reliably secures a gap between the connection terminals, and the solder layer electrically securely connects the connection terminals.

Therefore, first, according to the invention of claim 1,
To provide a solder ball having a simple structure, which can reliably connect the connecting terminals facing each other without short-circuiting the adjacent connecting terminals and can surely secure the gap between the connecting terminals facing each other. be able to.

Next, according to the invention of claim 2, a high-quality solder ball according to the invention of claim 1 can be easily and surely manufactured by a simple method. Can be provided by.

Finally, according to the third aspect of the present invention, a connection structure is provided with a simple structure in which a short circuit does not occur in the adjacent connection terminals and a gap can be reliably secured between the opposing connection terminals. Can be provided.

[0030]

[Brief description of drawings]

FIG. 1 is a sectional front view showing an embodiment of a solder ball according to the invention of claim 1. FIG.

FIG. 2 is a process drawing showing an embodiment of a method of manufacturing a solder ball according to the invention of claim 2;

FIG. 3 is a process drawing showing another embodiment of the method for manufacturing a solder ball according to the invention of claim 2;

FIG. 4 is a sectional front view showing an embodiment of the connection structure according to the invention of claim 3;

[Explanation of symbols]

 10 Metal Nucleus 10a Metal Ball 20 Solder Layer 20a Solder Ball 30 Container 40 Printed Wiring Board 41 Connection Terminal 100 Solder Ball

Claims (3)

[Claims] 1. A solder ball comprising a surface of a metal core coated with a solder layer having a melting temperature lower than that of the metal core. 2. A method of manufacturing a solder ball according to claim 1, comprising the following steps: (1) a metal ball serving as the metal core and the metal A step of putting a solder ball formed of a solder having a melting temperature lower than that of the ball and forming the solder layer into a container; (2) melting the solder ball at a temperature lower than the melting temperature of the metal ball to solder the surface of the metal ball To form a solder ball in which the surface of the metal core is covered with a solder layer. 3. A connection structure for electrically connecting opposing connection terminals with solder balls, wherein metal nuclei interposed between the respective connection terminals and a melting temperature lower than the metal nuclei and a surface of the metal nuclei. And a solder layer welded to each of the connection terminals.