Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Lead free soldering

pablowe

#26843

Lead free soldering | 13 January, 2004

We have done some trials with Lead free which appear to have gone well. We will be introducing a number of new products over the coming months and it is an opportune time to begin using lead free on these products which will be required by law in the near future anyway. My question is this, are the any issues in using Lead free solder with components and pcbs which are not lead free. I have heard that there is an issue with Bismuth in paste with non lead free components but I dont know the reason or what problems it causes, any one else got knowledge of this

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Loz

#26844

Lead free soldering | 13 January, 2004

check out http://www.aimsolder.com it has a good report on it. Report is called Lead-Contamination in Lead-Free Electronics Assembly.

Loz

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#26878

Lead free soldering | 13 January, 2004

Bismuth Solder alloys * Fatigue life is reduced when soldered to hot air solder leveled (HASL) boards. * Lead from Hot Air Leveling (HAL) coatings can diffuse through the grain boundaries of alloy. * Lead is bismuth alloys can form a eutectic composition of Bi52Pb32Sn16 in the grain boundaries. * Melting point of the eutectic alloy is 95 *C. * Overall result is a large decrease in the strength of the joint. * Fillet lifting of PTH due to pasty range (206-213 *C) * Avoid any lead!!

Search the fine SMTnet Archives for more background on lead-free / no-lead /etc.

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