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Lead-free solder alloy

A lead-free solder alloy, high-quality technology, applied in the direction of welding/cutting media/materials, welding media, welding equipment, etc., can solve the problems of soldering reliability damage, adverse effects of drop impact resistance, etc., to prevent solder alloys Yellowing, improvement of drop impact resistance, pore suppression effect

Active Publication Date: 2008-06-25
SENJU METAL IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If there is an error in the quality inspection of solder bumps, the reliability of soldering will be significantly impaired
In addition, since In is easily oxidized, a solder alloy containing a large amount of In increases the amount of oxidation with heating during solder bump formation or soldering, and a large number of pores are generated in the solder bump or solder joint, which improves the drop resistance. Impact has adverse effects

Method used

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  • Lead-free solder alloy

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0042] Solder balls having a diameter of 0.3 mm were fabricated using the solder alloys having the compositions shown in Table 1. Among the solder alloys shown as comparative examples in Table 1, Comparative Examples 1 and 2 exemplify solder alloys having typical compositions described in Patent Documents 1 and 23, respectively. Comparative Examples 3 and 5 exemplify the solder alloy described in Patent Document 3.

[0043] Using these solder balls, the drop impact resistance before and after thermal aging, the thickness of the alloy layer after thermal aging, yellowing due to heating, and generation of voids were investigated by the method described below. These results are combined and shown in Table 1. The heating in the reflow furnace or the constant temperature bath in each test was implemented in air atmosphere.

[0044] (drop impact resistance)

[0045] (1) On electrodes of a CSP having a size of 12×12 mm having 192 electrodes (copper-plated on the surface), flux was...

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Abstract

Disclosed is a lead-free solder alloy exhibiting improved drop impact resistance even after thermal aging while being good in soldering properties, void formation and discoloration. Specifically disclosed is a solder alloy consisting essentially of, in mass %, (1) 0.8-2.0% of Ag, (2) 0.05-0.3% of Cu, (3) one or more elements selected from not less than 0.01% and less than 0.1% of In, 0.01-0.04% of Ni, 0.01-0.05% of Co and 0.01-0.1% of Pt, and if necessary (4) one or more elements selected from Sb, Bi, Fe, Al, Zn and P in an amount of not more than 0.1% in total, and the balance of Sn and unavoidable impurities.

Description

technical field [0001] The present invention relates to a lead-free solder alloy that does not contain lead, and particularly relates to a lead-free solder alloy suitable for forming minute solder portions such as solder bumps. Background technique [0002] Solder bumps are often used to assemble ultra-small multifunctional packages such as BGA (Ball Grid Array) and CSP (Chip Size Package) to printed circuit boards. In this case, solder bumps are previously formed on the electrodes of the package, and the solder bumps are brought into contact with soldering portions (lands) of the printed circuit board to configure the package. Thereafter, when the printed circuit board is heated using a heating device such as a reflow oven to melt the solder bumps, the package is soldered to the printed circuit board, ensuring electrical conduction between the two. [0003] Solder bumps are also utilized for assembly of bare chips to printed circuit boards. This assembly method is also ca...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K35/26C22C13/00H05K3/34
CPCB23K35/262H05K3/3463C22C13/00
Inventor 大西司八卷得郎相马大辅
Owner SENJU METAL IND CO LTD
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