JPS6192797A - Sn-sb alloy solder - Google Patents

Abstract

PURPOSE:To improve the joining strength and fluidity of solder by incorporating specific weight % of Sb, Ni and P into the solder. CONSTITUTION:The Sn-Sb alloy solder coantg. 5-10wt.% Sb, 0.55-5wt.% Ni and consists of the balance Sn is formed. The alloy solder consisting of 5-10wt.% Sb, 0.55-5wt.% Ni, <=0.5wt.% P and the balance Sb is constituted as the other method. The addition of Sb is essential for high-temp. strength and the addition of P prevents the decreases in the fluidity owing to the addition of Ni. The formation of the intermetallic compd. Cu3Sn at the solder joint faces is effectively suppressed by the addition of Ni alone or the addition of both Ni and P. The joint strength is thus improved by the above-mentioned method and the solder fluidity is improved by the addition of P.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the improvement of Sn-Sb alloy solder, and in particular to the improvement of Sn-Sb alloy solder, in particular the intermetallic compound Cu3Sn, which is harmful to the joint strength of the solder joint surface.
In addition to suppressing the formation of solder and improving bonding strength, it also facilitates the formation of ribbon-shaped solder.

2. Description of the Related Art In general, Sn--Sb alloy solder is used as a high-temperature solder for joining various electrical and electronic parts. For example, in the case of a semiconductor such as a transistor, a preform material made of a ribbon-shaped Sn-3b alloy solder is used to bond the semiconductor I; onto a lead frame. Sn-
Although the high-temperature strength and creep properties of 3b alloy solder improve depending on the Sb content, it becomes hard and brittle depending on the Sb content m, so solder with an Sb content of 10 wt% or less is usually used.

(Problems to be Solved by the Invention) CLI or Cu alloys are mainly used for electrical and electronic parts in terms of heat dissipation characteristics, conductivity, and cost (A3S, these are Sn-3B based alloys on Qu based bases). When soldering is performed using alloy solder, the Cu base material (
1) and solder (2), an intermetallic compound Cu 3
Sn (3) and CLIsSn5 (4) are generated, reducing bonding strength. Especially Cu3Sn is Cu6
Vf compared to Sn s! Cu is highly durable, brittle, and has high electrical resistance, so Cu
Suppression of 3Sn production is strongly desired. Furthermore, if such a joint is left under high temperature, the Cu 3Sn phase will gradually grow and become thicker, deteriorating the joint strength over time.

To prevent this, conventionally, A
A method of forming a barrier by plating IJ, A(1, Ni, etc.) has been used, but it not only complicates the manufacturing process of the base material, but also has the disadvantage of being time-consuming and high cost. Furthermore, a preform material formed by molding ribbon-shaped solder is often used, but manufacturing ribbon-shaped solder has the drawback of being extremely labor-intensive and expensive.

[Means and effects for solving the problems] In view of this, the present invention has been made as a result of various studies, and the present invention has been made to have an Sb' content of 5 to iowt% (hereinafter wt% is simply abbreviated as %).

Ni 0.1-0.5%, P 0.005-0.5
% and the balance being Sn can effectively suppress the formation and growth of the intermetallic compound Cu 3 Sn, which is harmful to the strength of the joint surface, and has previously proposed this. After that, further studies revealed that in Sn-Sb alloy solder with a Ni content of 5% or less, the addition of Sb or Sb and P suppresses the formation of the intermetallic compound Cu 3 Sn and shows good bonding strength. As can be seen, the Sn-Sb alloy solder of the present invention has been developed.

One of the alloy solders of the present invention has 5 to 10% Sb.

It is characterized by containing 0.55 to 5% of Ni, with the remainder being Sn.

Another alloy solder of the present invention contains 5 to 10% Sb.

Contains Ni 0.55-5%, P5% or less, the balance is Sn
It is characterized by consisting of.

That is, the present invention uses the previously proposed Sn-Sb alloy solder to reduce the intermetallic compound Cu on the joint surface with the Cu base material.
3 As a result of a detailed study of the formation status of Sn, it was found that by adding Sb or Sb and P, Sn-3 containing 5% or less Ni
Even in b-based alloys, the formation of intermetallic compounds C1,13Sn is effectively suppressed, and a Sn-Sb-based alloy solder is obtained which has excellent bonding strength at high temperatures and is easily formed into a ribbon-shaped solder.

However, the reason why the composition of the Sn-3b alloy solder of the present invention is limited as described above is as follows.

The addition of 3b is an essential additive element to obtain high-temperature strength, and conventional Sn-Sb alloy solder (3bs ~ 10%)
In , the formation of the intermetallic compound Cu 3Sn was effectively suppressed by the addition of Ni or Ni and P, and the reason why the Ni content was limited to 0.55 to 5% was that the Ni content was 5%.
This is because, although the content is effective up to 5%, the viscosity increases and the spreadability not only deteriorates, but also makes it difficult to manufacture the solder. That is, in the production of Sn-Sb alloy solder, a Sn-Ni master alloy or an Sb-Ni master alloy is used to add Ni, so increasing Niff1 results in a master alloy with a high melting point, which not only results in the melting of the master alloy. It is also difficult to melt alloy solder.

The purpose of adding P is to improve the decrease in fluidity caused by the addition of N1, and the reason why the content is limited to 0.5% or less is to improve fluidity according to the amount of P added and to have a synergistic effect with the addition of N1. Although the high-temperature strength is improved by the content, if the content exceeds 0.5%, the solder not only becomes brittle but also corrodes the Cu-based base material.

The solder of the present invention is S melted in advance in an inert gas atmosphere.
n-Ni master alloy or 5b-Ni master alloy is used, and S
n and Sb are blended into a desired composition, melted in the atmosphere, and when P is added, P or a Sn-P master alloy is added to the molten metal.

The ingot thus melted and cast is formed into a desired wire or tape shape by conventional extrusion, rolling, wire drawing, or the like. If the preform material is to be molded into a thin ribbon, a C-shaped crucible (6) with a nozzle (7) at its lower end is placed on a cooling roll (5) that rotates in the direction of the arrow, as shown in Figure 2. Then, the above alloy is melted in the crucible (6), or the molten metal (8) is inserted, and the molten metal surface in the crucible (6) is pressurized to cause the molten metal to flow from the nozzle (7) onto the roll (5). (
By jetting out 8) and solidifying it directly from the molten metal into a ribbon (9), it is extremely easy to obtain 1'C.

In this case, especially if the alloy solder of the present invention to which P is added is used, surface oxidation can be reduced and connection failures due to oxidation can be prevented. Furthermore, compared to alloy tan solder that does not contain P, a ribbon with a smoother free surface can be obtained.

〔Example〕

Example (1) Sn-Ni master alloy and S melted in advance in a Δr atmosphere
The n-Pff1 alloy, Sn and Sb were blended into the composition shown in Table '1, and melted in an Elema furnace using a carbon crucible in the air. As shown in Fig. 3, the molten metal in the crucible (12) is maintained at a temperature of 280 to 300°C, and the Cu wire (11) with a diameter of 1 mm is inserted into the solder melt 1 (10) with a thickness of 0.2 mtn. Bend it into a hairpin shape in the gap and insert it.
It was dipped for 10 seconds and soldered. 2 per second for this
A pulling test was carried out using a mIn fastener, and the state of formation of the intermetallic compound CIJ 3Sn on the joint surface was investigated. In addition, after the above soldering, after holding at a temperature of 150°C for 110 hours, an intermetallic compound (CIJ 3 S) was formed on the joint surface.
Check the generation status of n. These results are also listed in Table 1.

Example (2) Using a part of the alloy solder having the composition shown in Table 1, as shown in Fig. 2, the molten solder was jetted from a nozzle onto a rotating cooling roll, and the molten metal was directly poured into a 12#, thick A ribbon with a thickness of 50 μm was prepared. Regarding this, we compared the fluidity of the solder and the surface condition. The results are shown in Table 2.

Table 2 [Note] ◎mark: Extremely good liquidity.

O mark: Good fluidity.

× Mark: Poor fluidity.

As is clear from Tables 1 and 2, conventional solder N02
Sample No. 7 produced an intermetallic compound CU 3 Sn on the joint surface, had a low soldering strength of 0.5 to 9, and had poor fluidity, making it impossible to create a thin ribbon. On the other hand, the present invention solders No. 1 to 20 did not produce the intermetallic compound Cu3Sn on the bonding surface and had an excellent drawing strength of 0.79 Kg or more, and especially those containing P had good fluidity. Therefore, it is extremely easy to create a thin ribbon, and compared with the comparison solder No. 26 proposed earlier, the t
It can be seen that there is almost no damage.

On the other hand, comparative solder Nα with Sb content exceeding 10%
Comparative solders No. 23 to 24 and Comparative solder No. 25 with a P content exceeding 0.5% all showed a significant drop in drawing strength, while comparative solder No. 21, 23, and 24 had poor fluidity and caused clogging in the nozzle. It was not possible to make it into a thin ribbon shape.

(Effects of the Invention) As described above, according to the solder of the present invention, it is possible to suppress the formation of intermetallic compounds at the joint surface with the Cu-based base material and improve the joint strength. In addition, the addition of P not only improves the fluidity of the solder and prevents oxidation, but also improves the joint strength and makes it easier to form thin ribbons, especially when the joints are left at high temperatures for long periods of time. This has remarkable industrial effects such as no deterioration in electrical connectivity even when the temperature is low.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the formation of the intermetallic compound CLI 3 Sn on the bonding surface between Sn-Sb alloy solder and Cu base material. Figure 2 is an explanatory diagram of the ribbon manufacturing method for thin ribbon-shaped solder. FIG. 3 is an explanatory diagram of the test method for tensile strength. 1, Cu base material 2, solder 3, intermetallic compound CLI 3 Sn 4, intermetallic compound CLI s Sn s5, rotating cooling roll 6.12. Crucible 7, nozzles a, io, molten metal 9. Ribbon 11, Cu wire Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) Sn-Sb alloy solder containing 5 to 10 wt% of Sb and 0.55 to 5 wt% of Ni, with the balance being Sn. (2) Sb5-10wt%, Ni0.1-5wt%, P
1. A Sn--Sb alloy solder comprising 0.5 wt% or less, with the remainder being Sn.