JPH07284983A - Solder material and production thereof - Google Patents

Abstract

PURPOSE:To provide a tape- or wire-shaped solder material of an Sn-Sb system having excellent ductility at a high temp. and excellent cold workability as a solder material for joining parts of a semiconductor device which entails heat generation. CONSTITUTION:The solder material which contains 5 to 15wt.% Sb and 2 to 15wt.% Ag and consists of the balance substantially Sn exclusive of inevitable impurities is melted in an inert atmosphere and the molten solder material is cast to form an ingot. This ingot is subjected to extruding and is further to cold working by rolling or drawing, by which the ingot is finished to a tape or wire of a specified shape and size. The surface roughness of such tape or wire is confined to <=Ra=10mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape or wire-shaped solder material and a method for producing the same, and more specifically, a Sn-Sb alloy solder material for joining components used at high temperatures,
In particular, the present invention relates to a tape-like or wire-like solder material having a small surface roughness for joining components of a semiconductor device which is used at high temperature because it is accompanied by heat generation.

[0002]

2. Description of the Related Art Generally, high temperature solder has a solidus temperature of Pb.
-Sn is a eutectic temperature (183 ° C) or higher. Usually, Sn is the main component, and Pb, In, Ag, S
It contains b, Cu, Ni and the like. In this, S
A solder containing Sb as the main component of n is preferable as a solder for high temperature because the high temperature strength and the creep characteristics are improved.
On the other hand, when a semiconductor element is bonded to a lead frame by using a solder containing Sn as a main component and containing only Sb, the heat generated by the semiconductor chip causes Sn-S.
There is a problem that cracks easily occur in the solder member.
Further, a tape or wire-shaped solder material having excellent surface roughness is required in order to prevent operational troubles during semiconductor mounting. In order to prevent cracks due to this heat generation and to obtain a tape or wire having excellent surface roughness, cold working such as rolling or wire drawing is generally performed.

Conventionally, Sn, Sb type solder is used for Ni, Cu, B.
Attempts have been made to incorporate i and the like, but they have the drawbacks of not being sufficiently effective in preventing cracks at high temperatures due to heat generation of semiconductor chips and making cold working difficult. Therefore, in Sn-Sb type solder, a solder material that is effective in preventing cracks at high temperatures and has good cold workability has not been obtained, so it is limited to applications such as ribbon solder and cream solder by direct rapid cooling of molten metal. However, its excellent high temperature strength and creep properties have not been fully utilized.

Here, the crack prevention at high temperature will be described in detail. Considering from the environment where the semiconductor device is practically exposed,
It is required to have excellent ductility at a temperature of 170 ° C. In addition, when describing cold workability in detail, segregation is likely to occur during casting when performing cold working through melting and casting processes to adjust to a predetermined shape and size, which also contributes to the fragility of the material. There is a phenomenon that hot working becomes difficult.

Japanese Unexamined Patent Publication No. 61-86091 discloses a ribbon solder in which Ni and P are added to Sn-Sb type solder to directly solidify it in a ribbon shape from a molten metal having improved high temperature bonding strength at 150 ° C. is doing. However, the environment to which semiconductor devices are exposed in practice is more severe, and higher temperatures (1
It is insufficient as a solder material having excellent ductility at 70 ° C. Further, since it contains Ni and P, it has a drawback that segregation during casting is likely to occur for cold working, which makes cold working difficult.

Japanese Unexamined Patent Publication (Kokai) No. 5-50286 discloses Sn-Ag-C.
Compared to the case where the u-based composition contains Bi or Pb, the temperature is -5 ° C to 1
Disclosed is a solder cream that provides a solder excellent in a thermal shock test at 25 ° C. And in this, 2% by weight of S
The example which added b is shown. However, even this composition system is insufficient as a solder material having excellent ductility at a higher temperature of 170 ° C. Further, since it contains Cu, it has a drawback that segregation during casting is apt to occur during cold working, which makes cold working difficult.

[0007]

In recent years, a solder material having a high ductility measured at 170 ° C. is required as an effective solder material for preventing cracks at a high temperature due to heat generation of a semiconductor chip. Further, a tape or wire-shaped solder material having excellent surface roughness is required in order to prevent operational troubles during semiconductor mounting. In order to obtain this tape or wire-shaped solder material having excellent surface roughness, it is required to have excellent cold workability. Here, the object of the present invention is to obtain a temperature 1
An object of the present invention is to provide a Sn-Sb-based tape or wire-shaped solder material having excellent ductility at 70 ° C and excellent cold workability.

[0008]

As a result of intensive studies by the present inventor, it was thought that the ductility decreases because the strength tends to increase as Sb in the Sn--Sb system increases, but unexpectedly. It was also found that when Sb is contained in a relatively high region of 5 to 15% by weight and 2 to 15% by weight of Ag is contained, excellent ductility at 170 ° C. is exhibited due to the synergistic effect. Further, since the cold working can be satisfactorily performed within this range, the surface roughness can be sufficiently satisfied, and the present invention has been completed. The present invention is as follows. (1) A tape or wire-shaped solder containing 5 to 15% by weight of Sb and 2 to 15% by weight of Ag, the balance being substantially Sn except for unavoidable impurities, and having a surface roughness Ra of 10 μm or less. material. (2) A tape or wire-like solder, which contains 6 to 11% by weight of Sb and 6 to 12% by weight of Ag, and the balance is substantially Sn except for unavoidable impurities and has a surface roughness Ra of 10 μm or less. material. (3) A tape or wire-shaped solder material comprising 5 to 15% by weight of Sb and 2 to 15% by weight of Ag, the balance being a solder material substantially composed of Sn except for unavoidable impurities and cold-worked. Manufacturing method. (4) A tape or wire-shaped solder material, which is obtained by cold-processing a solder material containing 6 to 11% by weight of Sb and 6 to 12% by weight of Ag, with the balance being substantially Sn except for unavoidable impurities. Manufacturing method.

[0009]

In the present invention, the reason why the composition of the solder material is limited as described above will be explained. Regarding solder containing Sn as a main component, Sb is effective in improving ductility at 170 ° C. in synergistic effect with Ag. The Sb content needs to be 5 to 15% by weight, and within this range, an effect of improving ductility at 170 ° C is produced. The content is more preferably 6 to 11% by weight, and in this range, the improvement of ductility at 170 ° C. shows a more excellent effect. And cold workability is favorable in these ranges. If the Sb content is less than 5% by weight, the effect of improving ductility at 170 ° C is insufficient. On the other hand, the Sb content is 15
If the content exceeds 10% by weight, the effect of improving ductility is insufficient and cold working becomes impossible.

Ag has a synergistic effect with Sb at 170 ° C.
It is effective in improving ductility. The content of Ag needs to be 2 to 15% by weight, and within this range, an effect of improving ductility at 170 ° C. occurs. More preferably 6 to 12% by weight
In this range, the improvement of ductility at 170 ° C. shows a more excellent effect. Cold working is possible within these ranges. If the Ag content is less than 2% by weight, the effect of improving ductility at 170 ° C is insufficient. On the other hand, the Ag content is 1
If it exceeds 5% by weight, cold working becomes impossible.

In the Sn-Sb type solder, the lower the Sb content, the lower the normal strength and the higher the ductility. Therefore, when the Sb content is as small as 3% by weight, the temperature is 170 ° C.
Although it is expected that the ductility in
It is not clear why a higher b content of 5 to 15% by weight has an excellent effect of improving ductility at 170 ° C.
It is considered to be due to a synergistic effect with n, Sb, and Ag.

Next, the manufacturing method of the present invention will be described.
The solder material of the present invention is prepared by mixing a predetermined amount of Sn, Sb, and Ag, melting it in an inert atmosphere, and casting this to form an ingot. The ingot is extruded and then cold-worked by rolling or wire drawing to finish a tape or wire having a predetermined shape and size. The surface roughness of the material thus rolled or drawn is Ra = 1 μm.
Although it was sufficiently smaller than a = 10 μm, the wire obtained by the ultra-quenching method had a surface roughness Ra of about 70 μm and had poor cold workability. Incidentally, in the production method of the present invention, if necessary, it is used in the state of so-called grain-containing solder that has been subjected to cold working by mixing particles in the tape or wire, or pellets from the tape thus produced. It can be punched out and used.

[0013]

【Example】

(Examples 1 to 14, Comparative Examples 1 to 8) Each metal element in the solder wire was blended so as to have the composition shown in Table 1 and Table 2, melted and cast in a nitrogen atmosphere, and the diameter was 70 mm x length. 10
A 0 mm ingot was created. This was heated to 150 ° C. and extruded into a wire having a diameter of 1 mm. Further, wire drawing was performed to finish a wire having a diameter of 0.3 mm. The cold workability at that time is shown in the table. Next, this wire drawn material is heated to 170 ° C.
A tensile test was carried out in the state of being heated to measure elongation (%) and surface roughness. The results are shown in the table.

Example 15 Each metal element in the solder tape was blended so as to have the composition shown in Table 1, melted and cast in a nitrogen atmosphere to prepare an ingot having a diameter of 30 mm and a length of 100 mm. This is heated to 150 ° C and the thickness is 1mm x
It was extruded to a width of 20 mm. Further rolling is performed to a thickness of 0.3
The tape was finished to have a size of mm × width 20 mm. The cold workability at that time is shown in the table. Next, this rolled material was subjected to a tensile test while being heated to 170 ° C., and the elongation rate (%) and the surface roughness were measured. The results are shown in the table.

Comparative Example 9 Each metal element in the solder wire was blended so as to have the composition shown in Table 2 and melted in a nitrogen atmosphere. 7 liters of water was injected into a cylindrical drum rotating at 250 rpm to form a water layer, and the molten metal was upwardly directed to a water layer in the rotating cylindrical drum from a quartz nozzle having a hole diameter of 1 mm by argon gas pressure. It was jetted and rapidly solidified. The wire obtained was tried to be drawn, but Table 2
As shown in, the wire drawing workability was extremely poor. Therefore, for Comparative Example 9, the elongation percentage (%) and the surface roughness in the state of a wire having a diameter of 1 mm were measured and shown in the table.

[0016]

[Table 1]

[0017]

[Table 2]

Here, cold workability means, in the case of a wire,
Weight 1k when drawing wire from diameter 1mm to 0.3mm
The number of wire breakages per g was measured and evaluated as follows. ◯: When the number of wire breaks is 2 or less Δ: When the number of wire breaks is 3 to 4 ×: When the number of wire breaks is 5 or more Not possible: When wire drawing is not possible Also, in the case of tape, rolled from 1 mm to 0.3 mm in thickness The size of the maximum edge crack in the tape width direction at the time of processing was measured, and the ratio to the tape width was defined as the edge crack rate, and evaluated as follows. ◯: When the cracking rate is 5% or less Δ: When the cracking rate is more than 5% and less than 25% ×: When the cracking rate is 25% or less No: When rolling is not possible

As is apparent from Table 1, a solder material containing 5 to 15% by weight of Sb and 2 to 15% by weight of Ag, the balance being substantially Sn except for unavoidable impurities, is subjected to cold working. All of Examples 1 to 15 are excellent in cold workability, the elongation rate at 170 ° C is 25% or more, and the Sb content is 6 to 11% by weight and the Ag content is 6 to 12%. Examples 2 to 6, 10 to 12, 1% by weight
It can be seen that in No. 5, the elongation at 170 ° C. is 38% or more, which is even better.

On the other hand, Comparative Examples 1 to 6 in which the contents of Sb and Ag are out of the range of the present invention, Comparative Example 7 in which the composition of Sn—Sb—Ni system, and Sn—Sb—Ag—Cu composition were used. In Comparative Example 8 in which the elongation rate at 170 ° C. is 21%
It is understood that the following is true, and in Comparative Examples 3, 5 and 6, wire drawing is impossible, and in Comparative Examples 7 and 8, wire breakage frequently occurs during wire drawing.

Further, as in Comparative Example 9, Sn, Sb, A
It can be seen that even if the blending amount of g is within the range of the present invention, the wire produced by the rapid solidification method has extremely poor wire drawing workability and the surface roughness in the wire state is about Ra = 70 μm. .

Next, the experimental example shown in FIGS. 1 and 2 will be described. FIG. 1 shows a tape or wire-shaped solder material obtained by cold-processing a solder material having an Sb content of 8.5% by weight, an Ag content of 0 to 25% by weight, and the balance being substantially Sn except for unavoidable impurities. It is the graph which measured the elongation rate in 170 degreeC of. FIG. 2 is a tape or wire-shaped solder material obtained by cold-processing a solder material that has an Ag content of 7.5% by weight, an Sb content of 0 to 15% by weight, and the balance is substantially Sn except unavoidable impurities. It is the graph which measured the elongation rate in 170 degreeC of.

As is clear from FIG. 1, the Ag content is 2
It can be seen that the elongation rate is as good as 25% or more in the range of ˜15% by weight, and the elongation rate is even better in the range of Ag content of 6 to 12% by weight. See also FIG.
As is clear from the above, the elongation percentage is as good as 25% or more in the Sb content range of 5 to 15% by weight, and the S
It can be seen that the elongation is even better when the b content is in the range of 6 to 11% by weight.

[0024]

As described above, the tape or wire-shaped solder material according to the present invention has a remarkably excellent elongation in a tensile test at 170 ° C. and good cold workability. Therefore, it has excellent surface roughness. Therefore, it is possible to suppress the occurrence of cracks in the Sn—Sb solder member due to the heat generation of the semiconductor chip and to improve the surface roughness of the S-Sb solder member.
An n-Sb-based tape-shaped or wire-shaped solder material can be provided, and exhibits extremely suitable effects when used for connection between a semiconductor chip and a lead frame substrate, for example.

[Brief description of drawings]

FIG. 1 Sb content is 8.5% by weight, Ag content is 0 to 2
It is a graph which measured the elongation rate in 170 ° C of the tape or wire-like solder material which carried out cold processing of the solder material which consists of 5 weight% and the balance except Sn inevitable impurities, and consists essentially of Sn.

FIG. 2 Ag content of 7.5% by weight, Sb content of 0 to 1
It is a graph which measured the elongation rate in 170 ° C of the tape or wire-like solder material which carried out cold processing of the solder material which consists of 5 weight% and the balance except Sn inevitable impurities, and consists essentially of Sn.

Claims (4)

[Claims] 1. A tape or wire containing 5 to 15% by weight of Sb and 2 to 15% by weight of Ag, the balance being substantially Sn except for unavoidable impurities, and having a surface roughness Ra of 10 μm or less. Solder material. 2. A tape or wire comprising 6 to 11% by weight of Sb and 6 to 12% by weight of Ag, the balance being substantially Sn except for unavoidable impurities, and having a surface roughness Ra of 10 μm or less. Solder material. 3. A tape or wire shape, which is obtained by cold working a solder material containing 5 to 15% by weight of Sb and 2 to 15% by weight of Ag, the balance being substantially Sn except for unavoidable impurities. Solder material manufacturing method. 4. A tape or wire shape, which is obtained by cold working a solder material containing 6 to 11% by weight of Sb and 6 to 12% by weight of Ag, the balance being substantially Sn except for unavoidable impurities. Solder material manufacturing method.