JPH02179387A - 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 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 1% >=1 kinds among Cu, In and Ga thereto. 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.

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.

[Conventional technology]

Solder is generally a 5n-Pb alloy, and is widely used in the electronic industry to connect electrical circuits and to join some ceramics and metals.

[Problem to be solved by the invention]

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

Furthermore, when bonding ceramics and metals, MO-Mn or the like is metallized on the ceramic side to ensure compatibility with solder (brazing material), and Ag-Cu-based Ag brazing material is sometimes used; In the ceramic substrate of
There is a problem in that the ceramic substrate may crack due to the difference in thermal expansion with the bonding metal.

[Means to solve problems]

The present invention comprises 10 to 30% by weight of Ag, 70 to 90% by weight of Sn, and 0.05 to 5% by weight of one or more of Cu, In, and Ga. The presence of Ag-5n, a eutectic alloy, as a basic component lowers the melting point, the presence of Ag improves corrosion resistance and electrical and thermal conductivity, and the presence of one or more of Cu, In, and Ga improves solderability. The purpose is to improve the mechanical strength of the material itself.

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%, it will be difficult to The processability of the solder decreases, and the liquidus temperature increases, making it difficult to call it a solder.

In addition, one or more of Cu, In, and Ga is added at a weight ratio of 0.0
The reason why it is limited to 5 to 5% is that if it is less than 0.05%, no improvement in mechanical strength can be expected, and if it exceeds 5%, it is difficult to form a solid solution and may cause segregation, which may actually impair the properties of the material. This will lead to a decrease in

〔Example〕

1st Example 500 g of Ag, 445 g of Sn, and 5 g of Cu
After melting g in a Tanman furnace and forging and cutting an ingot,
By repeating rolling and annealing, a thin plate with a thickness of 0.1 was processed.

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 is as shown in the figure, thickness 0.5 am, width 6 mm
A 511III square brazing metal with a thickness of 0.1 mm was sandwiched between two Cu strips of 200 m in length, 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 of
The condition was observed after holding at a high temperature for 5 minutes.

Second Example AAg30g5Sn425. Cu24g, In0.25
A total of 500 g of 0.75 g of Ga and 0.75 g of Ga was melted in a Tammann furnace, and after forging and cutting the ingot, rolling and annealing were repeated to process a thin plate with a thickness of 0.1 M.

This thin plate was cut to a width of 5 mm and a length of 200 mm, and annealed to prepare samples 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, a 5 mm square piece of wax with a thickness of 0.1 mm was placed between two Cu strips with a thickness of 0.5 tm, a width of 61II11, and a length of 200 m. The material was sandwiched, and the brazing was measured later and shown in the table.

In addition, the spreadability (wettability) is also the same as in the first embodiment.
N! using i board and Cu board! The temperature was maintained at 40°C higher than the melting point (liquid phase) for 5 minutes in a mixed gas of +Ht, 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 CuS In and Ga to the basic components of Ag and Sn, it has the effect of excellent corrosion resistance and improved electrical and thermal conductivity. It has the effect of being free of harmful ingredients such as.

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) (]r) 7゜Contents of amendment l. [The drawing is] on page 7, line 12 of the specification is amended to read ``Figure 1 dated May 22, 1989.'' 2゜(1) (n) of the drawing is amended as shown in the attached sheet.

Claims (1)

[Claims] 1. Ag 10-30% by weight, Sn 70% by weight
A low melting point Ag solder characterized by comprising ~90% and 0.05~5% by weight of one or more of Cu, In, and Ga.