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Lead-free solder

A lead-free solder and brazing technology, applied in the direction of welding/cutting media/materials, welding media, welding equipment, etc., can solve the problems of high melting temperature of solder, limited use, etc., achieve improved wettability, excellent impact resistance, The effect of high reliability

Active Publication Date: 2011-05-18
SENJU METAL IND CO LTD
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  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

Therefore, the melting temperature of solder is high, and its use is limited

Method used

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Examples

Experimental program
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Effect test

Embodiment

[0043] Using lead-free solders having the compositions shown in Table 1, tin pest, impact resistance and diffusion were tested in the following manner. The Pb content in the used alloy raw materials is all 300ppm or less. The alloys of sample Nos. 1 to 3 in the table have compositions of the present invention. The test results are also shown in Table 1.

[0044] Table 1

[0045]

[0046] Tin pest test

[0047] Lead-free solder of each composition was cast into an open mold (boat shape) with a long side of 30 mm, a short side of 20 mm, and a length of 200 mm to obtain a rod-shaped casting. The outer periphery of the casting was cut with a rotary disc to obtain a rod-shaped solder sample with a diameter of 8 mm and a length of 110 mm. After leaving this rod-shaped sample in a refrigerator at -40° C. for 10,000 hours, it was taken out from the refrigerator, and its surface was visually observed.

[0048] The evaluation that the surface of the rod-shaped sample has not cha...

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PUM

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Abstract

Disclosed is a low-cost lead-free solder having good wettability and impact resistance, wherein occurrence of tin pest is prevented at extremely low temperatures. The lead-free solder has a composition consisting of, in mass%, 0.5-0.8% of Cu, not less than 0.1% but less than 1% of Bi, 0.02-0.04% of Ni and the balance of Sn.

Description

technical field [0001] The present invention relates to a Sn-Cu-based lead-free solder suitable for soldering electronic devices, which does not generate tin pest even at an extremely low temperature of -40°C or lower, and is excellent in diffusivity and impact resistance. Background technique [0002] Pb—Sn solder has been used for joining metals from ancient times. Pb—Sn solder has been widely used in recent years for soldering of electronic devices, especially for soldering of electronic components to printed circuit boards. The melting point of Pb-Sn solder eutectic composition (Pb-63Sn) is 183°C, and soldering can be performed at a temperature below 240°C, so it does not cause thermal influence on electronic components and printed circuit boards. In addition, Pb—Sn solder near the eutectic composition has excellent wettability, has excellent characteristics such as no soldering defects, and contributes to ensuring the reliability of electronic equipment. [0003] Howe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K35/26C22C13/00
CPCB23K35/262H05K3/3463C22C13/02C22C13/00
Inventor 大西司田口稔孙
Owner SENJU METAL IND CO LTD
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