JPS6186091A - Sn-sb alloy solder - Google Patents

Abstract

PURPOSE:To improve joint strength and to form easily ribbon-shaped solder by adding a specific ratio of Ni and P to Sn-Sb alloy solder thereby suppressing the formation of a harmful intermetallic compd. CONSTITUTION:The Sn-Sb alloy solder is composed of 5-10wt% Sb, 0.1-0.15wt% Ni, 0.005-0.5wt% P and the balance Sn. The formation of the intermetallic compd. Cu3Sn harmful for the joint strength of solder joint surfaces is thus suppressed and the joint strength is improved. The fluidity of the solder is further improved and the formation of the ribbon-shaped solder is made easy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the improvement of Sn-3b alloy solder, and in particular, the intermetallic compound Cu 3 which is harmful to the joint strength of the solder joint surface.
This suppresses the formation of Sn to improve bonding strength and facilitates the formation of ribbon-shaped solder.

[Conventional technology]

Generally, 5n-8b alloy solder is used as a high-temperature solder for joining various electrical and electronic parts. For example, in semiconductors such as transistors, a preform material made of ribbon-shaped 5n-8b alloy solder is used to bond a semiconductor element onto a lead frame. Sn-3
Although the high-temperature strength and creep properties of b-based alloy solder improve depending on the Sb content, it becomes hard and brittle depending on the Sb content, so solder with an Sb content of 10 wt% or less is usually used.

[Problem that the invention seeks to solve]

Cu or Qu gold alloys are mainly used for electrical and electronic parts due to their heat dissipation properties, conductivity, and cost, and electrical and electronic parts are soldered onto these base materials using 5n-8b alloy solder. Then, as shown in Figure 1, an intermetallic compound Cu is formed on the joint surface of the CLI base material (1) and the solder (2)
5Sn(3) and CueSns(4) are generated, and the bonding strength decreases. In particular, C5Sn is Ctl s Sn s
Compared to Cu 3 Sn, Cu 3 Sn production is strongly desired to be suppressed because it has a high altitude, is brittle, and has a large electrical resistance. Furthermore, if such a joint is left at a relatively high temperature, the CD
3 The Sn phase gradually grows and becomes thicker, causing deterioration over time.

In order to prevent this, conventionally, aluminum was applied to the joint surface of the Cu base material.
A method of forming a barrier by plating I, A+It, Ni, etc. has been used, but this method has the disadvantage that not only the manufacturing process of the base material is complicated but also the cost is high.

[Means and effects for solving the problems] In view of this, as a result of extensive research, the present invention suppresses the formation of the intermetallic compound Cu33n, which is harmful to the joint strength of the solder joint surface, and improves the joint strength. We have developed a 5n-8b alloy solder that improves solder fluidity and can be easily formed into ribbon-shaped solder, containing 5 to 10 wt% of Sb (hereinafter wt% is simply abbreviated as %), Nio, 4 to 0. 5%.

It is characterized by consisting of P 09005-0.5% and the balance Sn.

That is, the present invention uses conventional 5n-8 containing 5 to 10% sb.
Regarding b-based alloy solder, in order to suppress the formation of intermetallic compound Cu 3 Sn on the joint surface with CLI base material,
As a result of examining various additive elements, we found that the addition of Ni and P was effective, and as a result of further frugality, we created a 5n-5b alloy that has excellent bonding strength at high temperatures and is easily formed into ribbon-shaped solder. It is something that

However, the reason why the composition of the Sn-8b alloy solder of the present invention is limited as described above is as follows.

The addition of N1 mainly suppresses the formation of the intermetallic compound CLI s Sn at the joint surface with the Cu base material, and the addition of P mainly increases the fluidity of the solder to facilitate the formation of the solder ribbon. The bonding strength at high temperatures is improved due to the additive effect, and the Ni content is 0.1 to 0.
．． The reason for limiting it to 5% is that if it is less than 0.1%, the effect of suppressing the formation of the intermetallic compound CU 3Sn on the bonding surface with the Cu-based substrate will be insufficient, and if it exceeds 5%, the viscosity of the solder will increase and the solder This is because it impairs the spreadability and furthermore, it becomes difficult to manufacture the solder. That is, Sn-8b
In the production of alloy solder, Sn-Ni is used to add Ni.
A mother alloy is used, but increasing the amount of Nil results in a mother alloy with a high melting point, making it difficult not only to melt the mother alloy but also to melt the alloy solder.

The P content is limited to 0.005 to 0.5% because if the P content is less than 0.005%, the fluidity of the solder is insufficient, and if it exceeds 0.5%, the solder becomes somewhat brittle. This is because it not only corrodes Cu.

The solder of the present invention uses a 5n-Ni master alloy or a 5b-Ni master alloy melted in advance in an inert gas atmosphere, blends Sn and sb into the desired composition, and melts it in the atmosphere. It is made by adding P or 5n-P master alloy to the molten metal. In order to form it into a desired shape such as a stranded wire or tape, ordinary extrusion processing, rolling processing, wire drawing processing, etc. may be applied. In addition, in order to make a thin ribbon for molding the preform material, a cooling roller (5-5
), a crucible (6) provided with a nozzle (7) at the lower end is arranged, and the above-mentioned alloy is melted in the crucible (6), or the molten metal (8) is charged, and the crucible (6) is It can be obtained very easily by pressurizing the surface of the molten metal, jetting the molten metal from the nozzle (7) onto the roll (5), and directly solidifying the molten metal (8) into a ribbon (9).

〔Example〕

Example (1) 5n-Ni master alloy melted in advance in an Ar atmosphere, 5n
-p master alloy, Sn and sb were blended into the composition shown in Table 1, and melted in the atmosphere using a carbon crucible and an Elema furnace. As shown in Fig. 3, the molten metal (1o) is maintained at a temperature of 280 to 300°C,
Cul with a diameter of 1M inside o>! (11) to 0.2#l#+
(7) It was bent into a hairpin shape in the gap, inserted, immersed for 10 seconds, and soldered. A pulling test was conducted on this at a speed of 2 mm/sec, and the formation of the intermetallic compound Cu3Sn on the joint surface was investigated.

In addition, after the above soldering, after holding at a temperature of 150'Q for 110 hours, an intermetallic compound Cu s was formed on the joint surface.
The generation status of Sn was investigated. These results are also listed in Table 1.

The X mark indicates Cu 3Sn generation thickness at the bonding interface of 0.2μ or more Example (2) Each solder shown in Table 1 of Example (1) is charged into the crucible shown in Figure 2 and placed on a rotating cooling roll. Spray on the width 1
After forming a ribbon of 2 m and a thickness of about 507 FL and examining its surface condition, a 1# square test piece was punched out from the ribbon and cut on a block made of 845 C heated to 500°C. Raised on a Cu plate of 0.3IWR, N280
%, Hz 20% mixed gas 10λ/10 8! The fluidity of the solder was investigated by soldering with moving spray.

The results are shown in Table 2.

Table 2 [Note] ○ indicates extremely good fluidity Δ indicates good fluidity X indicates poor fluidity As is clear from Tables 1 and 2, conventional solder N11
In Nos. 13 and 14, an intermetallic compound Cussn is generated at the bonding interface, and the bonding strength is around 0.5K9, whereas the present invention solders Nα1 to 14, in which Ni and P are added, have a bonding strength of around 0.5K9.
9, intermetallic compound CD 3 at the bonding interface
The generation and growth of Sn is extremely low, and the bonding strength is 0.9.
It can be seen that the weight is 6 kg or more, which is excellent, and the fluidity is also good. It is also seen that the solder of the present invention can be easily formed into ribbons, and all the ribbons obtained have a silvery white color and the free surface of the ribbon is smooth.

On the other hand, in the comparative alloy NQ10, which has a low Ni content and does not contain P, the intermetallic compound Cu 3 is present at the bonding interface.
Generates Sn, has low bonding strength, poor fluidity, and
Comparative alloy Nci1 with high i content and no P
1, the gold mI! at the bonding interface! I compound Q u33
Although the generation of u is small and a certain degree of bonding strength can be obtained, the fluidity is poor. Furthermore, even if the sb and Ni-containing forts are within the range of the present invention, Comparative Alloy 12 with a high P content has superior fluidity and is easier to form into ribbons, but it is found that the bonding strength is significantly inferior.

〔Effect of the invention〕

As described above, according to the solder of the present invention, in solder joints using CLI base materials, the intermetallic compound Cu3S at the joint interface
It suppresses the formation of AU, A!n on the base material. +, N
Although plating such as i is omitted, a highly reliable solder joint can be obtained.

In particular, in the production of ribbons, it is possible to produce ribbons with good surface conditions semi-continuously without causing troubles such as cutting, which brings about remarkable industrial effects.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the state of formation of intermetallic compound Cu 3Sn at the bonding interface during soldering of CLI base materials, FIG. 2 is an explanatory diagram showing an example of ribbon production of the solder of the present invention,
FIG. 3 is an explanatory diagram showing a method for measuring soldering strength. 1, CLI base material 2, solder 3, intermetallic compound CLI3Sn 4, intermetallic compound Cu63 n4 5, cooling roll 6, crucible 7, nozzle 8, molten metal 9, ribbon 10, molten metal 11, Quli

Claims (1)

[Claims] Sb5-10wt%, Ni0.1-0.5%wt%, P
A Sn-Sb alloy solder comprising 0.005 to 0.5 wt%, the balance being Sn.