JPH02179388A - Low melting point ag solder - Google Patents

Abstract

PURPOSE:To improve the mechanical strength of the solder itself by consisting the solder of specific weight ratios of Ag and Sn as its basic components and adding >=1 kinds among Cu, In and Ga and >=1 kinds of Fe and Ni thereto. CONSTITUTION:The low melting point Ag solder is composed by adding, by weight, 10 to 30% Ag, 70 to 90% Sn, and further 0.05 to 5% >=1 kinds among Cu, In and Ga thereto and further, adding 0.05 to 1% >=1 kinds of the Fe and Ni. The m. p. of the solder is, therefore, lowered by using the Ag-Sn of the eutectic type alloy as the basic components and the corrosion resistance and electrical and thermal conductive characteristics are improved by the presence of the Ag. Further, the mechanical strength of the solder itself is improved by the presence of >=1 kinds among the Cu, In and Ga and >=1 kind of the Fe and Ni.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a low melting point solder containing Ag as a main component.

[Prior Art] Solder is generally a 5n-Pb alloy, and is widely used in the electronic industry for connecting electric circuits and for joining some ceramics and metals.

[Problem to be solved by the invention]

However, 5n-Pb solder has low corrosion resistance.
There is a problem that electrical and thermal conductivity is low, and there is also a problem that Pb vapor and powder are harmful to engineers.

In addition, when joining ceramics and metals, Mo-Mn or the like is metallized on the ceramic side to ensure compatibility with the solder (brazing material), and Ag-CU-based Ag solder is sometimes used, but thin plate Ceramic substrates have the problem of causing cracks in the ceramic substrate due to the difference in thermal expansion between the ceramic substrate and the bonding metal.

[Means to solve problems]

The present invention contains 10 to 30% by weight of Ag, 70 to 90% by weight of Sn, 0.05 to 5% by weight of at least one of CuS In and Ga, and 0.05 to 5% of at least one of Fe and Ni. By using Ag-3n, a eutectic alloy, as the basic component, the melting point is lowered, and the presence of Ag improves corrosion resistance and electrical/thermal conductivity. The mechanical strength of the solder itself is improved by the presence of one or more of Cu, In, and Ga.

The reason why Ag is limited to 10 to 30% by weight in the present invention is that if it is less than 10%, the corrosion resistance and electrical/thermal conductivity will not reach the desired values, and if it exceeds 30%, the Processability decreases and the liquid phase point increases, making it difficult to call it solder.

In addition, one or more of Cu, In, and Ga are added at a weight ratio of 0.05.
The reason why it is limited to ~5% is that if it is less than 0.05%, no improvement in mechanical strength can be expected, and if it exceeds 5%, the liquidus point will increase and it will cause segregation.

In addition, 0.05 to 1% by weight of one or more of Fe and Ni
The reason for limiting the amount is that if it is less than 0.05%, no improvement in mechanical strength can be expected, and if it is added more than 1%, it will be difficult to form a solid solution, which will actually lead to a decrease in the properties.

〔Example〕

1st example Ag50g, 5n442.5g, Cu5g, Ni2.5
A total of 500g of g is melted in a Tamman furnace, and after forging and cutting an ingot, rolling and annealing are repeated until the ingot has a thickness of 0.1
The thin plate of the plate was processed.

This thin plate was cut to a width of 5 m and a length of 200 mm, and annealed to obtain a sample for measuring tensile strength, elongation, and hardness.

The shear strength is as shown in the figure (thickness: 0.5 mm, width: 6 m)
m, a thickness of 0.1 between two Cu strips of length 200 plates.
A 5ff II 11 square brazing material was sandwiched between the cylinders, and the brazing was measured afterward and shown in the table.

In addition, the spreadability (wettability) was determined using Ni plates and Cu plates.
z +H, 40°C above the melting point (liquid phase) in a mixed gas
The condition was observed after holding at a high temperature for 5 minutes.

Second Example Ag50g, SSn425g5Cu24. In0.25
500g, total of 0.5g Ni, 0.25g Fe
was melted in a Tammann furnace, the ingot was forged and cut, and rolled and annealed repeatedly to produce a thin plate with a thickness of 0.1M.

This thin plate was cut to a width of 5 mm and a length of 200 mm, and annealed to prepare a sample for measuring tensile strength, elongation, and hardness.

The shear strength was also the same as in the first embodiment, and as shown in the figure, 5 dish squares with a thickness of 0.1 mm were placed between two Cu strips with a thickness of 0.5 mm, a width of 6 mm, and a length of about 200 mm. A brazing material was sandwiched between the two, and the brazing was measured afterwards and shown in the table.

In addition, the spreadability (wettability) is also the same as in the first embodiment.
Using an i plate and a Cu plate, the temperature was maintained at 40°C higher than the melting point (liquid phase) for 5 minutes in a mixed gas of N2 moH2, and the state was observed.

The third to eighth examples were carried out in the same manner, and the results are shown in the table.

For comparison, as a conventional example, 60wt%5n-P
The b alloy and the 40 wt % 5n-Pb alloy were processed into the same dimensions as in the example, and the same measurements were performed.

〔Effect of the invention〕

According to the present invention described above, by adding one or more of Cu, In, and Ga and one or more of Fe and Ni to the basic components of Ag and Sn, it has excellent corrosion resistance and has improved electrical and thermal conductivity. It also has the effect of being free of harmful components such as Pb.

In addition, compared to conventional 5n-Pb solder, it has higher tensile strength and
Mechanical properties such as shear strength and hardness are approximately twice as high, and significant effects are recognized in these areas.

[Brief explanation of the drawing]

The drawing is a perspective view of a measurement sample for conducting a shear strength test. Patent applicant Toku Chikara Co., Ltd. Head office agent
Patent attorney Chikane Kura Takashi (I) (II) Procedural amendment method (method) Amend "The drawing is" on page 7, line 13 of the specification to read "Drawing 1 dated May 22, 1989." 2゜Amend (1) (n) of the drawing as shown in the attached sheet.

Claims (1)

[Claims] 1. Ag 10-30% by weight, Sn 70% by weight
~90%, one or more of Cu, In, and Ga at a weight ratio of 0.
05 to 5%, and one or more of Fe and Ni in a weight ratio of 0.05 to 5%.
A low melting point Ag solder characterized by comprising 0.05 to 1%.