Solder alloy

An alloy and process technology, applied in the field of alloys

Active Publication Date: 2008-02-27
爱尔发加热有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] However, there are issues associated with some conventional lead-free eutectic or near eutectic solder compositions used in wave soldering, reflow soldering, hot air leveling processes and ball grid arrays

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0124] The alloy was prepared by melting Sn in a cast iron crucible (as an alternative a ceramic crucible could be used). Sn-3 wt% Cu alloy, elemental Bi and alloys of Sn-5 wt% Ag and Sn-0.6 wt% Ni were added to the molten Sn. These additions were made at an alloy bath temperature of 350°C. The bath was cooled to 300°C so that phosphorus was added in the form of alloy Sn-0.3%P.

[0125] Alloys were sampled to verify the following compositions:

[0126] Ag 0.3wt%

[0127] Cu 0.7wt%

[0128] Bi 0.12wt%

[0129] Ni 0.04wt%

[0130] P 0.005wt%

[0131] and balance tin.

[0132] Alloys are cast into ingots. It is later remelted into a solder bath as a wave soldering machine. The molten alloy at a bath temperature of 260°C was pumped to create two solder waves close to each other.

[0133] The machine is used to create joints between board terminations and components on a range of single and double sided printed circuit boards. The incidence of defects requiring repair is...

Embodiment 2

[0135] The alloy according to example 1 can also be used in a hot air solder leveling bath. The temperature was set to 260°C and the machine was set so that the contact time with the solder plate ranged from 2.5 seconds at the top of the PCB board to 5 seconds at the bottom of the board. The air knife temperature was 295°C. Excellent tinning results with a clean surface finish and consistent tinning thickness are achieved.

Embodiment 3

[0137] Prepare the following alloy compositions (units are wt.%)

[0138] Ag 0.3

[0139] Cu 0.6

[0140] Bi 0.13

[0141] Ni 0.03

[0142] Co 0.02

[0143] P 0.004

[0144] Sn margin

[0145] This alloy was prepared in a similar manner to Example 1. Cobalt was added in the form of a master alloy of Sn-0.3 wt% Co. Fill the solder into the wave solder bath, melt it, and set the temperature to 260°C. The solder boards were fluxed with AlphaFry EF6000 flux and the boards were then wave soldered. Joints formed cleanly, the level of bridging was low, and hole filling was excellent.

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PUM

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Abstract

An alloy suitable for wave soldering process, reflow soldering process, hot air leveling process or ball grid array, the alloy comprises: 0.08-3wt.% bismuth; 0.15-1.5wt.% copper; 0.1-1.5wt.% 0-0.1wt.% of phosphorus; 0-0.1wt.% of germanium; 0-0.1wt.% of gallium; 0-0.3wt.% of one or more rare earth elements; 0-0.3wt.% .% indium; 0-0.3wt.% magnesium; 0-0.3wt.% calcium; 0-0.3wt.% silicon; 0-0.3wt.% aluminum; 0-0.3wt.% zinc; and at least one of the following elements: 0.02-0.3wt.% nickel; 0.008-0.2wt.% manganese; 0.01-0.3wt.% cobalt; 0.01-0.3wt.% chromium; 0.02-0.3wt.% % of iron; and 0.008 to 0.1 wt. % of zirconium; and the balance of tin and inevitable impurities.

Description

technical field [0001] This invention relates to alloys, particularly lead-free solder alloys. The alloy is particularly, but not exclusively, suitable for applications such as wave soldering, reflow soldering, hot air leveling and ball grid array and chip scale package ) for electronic welding applications. Background technique [0002] For environmental reasons, there is an increased demand for lead-free alternatives to lead-containing conventional alloys. Many conventional solder alloys are based on the tin-copper eutectic composition Sn-0.7 wt.% Cu. EP-A-0336575 describes low toxicity alloy compositions for joining and sealing, in particular lead-free alloys for use as pipe brazing filler metals. [0003] Wave soldering (or pour soldering) is a widely used method for mass soldering electronic assemblies. It can be used, for example, in through-hole circuit boards where the board is passed over a wave of molten solder that surrounds the bottom of the board to wet the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K35/26C22C13/00
CPCB23K35/262C22C1/06B23K35/26C22C13/00C22C13/02
Inventor 安东尼·英厄姆格拉尔德·坎贝尔布赖恩·刘易斯巴瓦·辛格约翰·劳克林兰吉特·潘赫尔
Owner 爱尔发加热有限公司
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