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SMT electronics assembly manufacturing forum.


Lead Free Component on solder paste (lead)

Visionlight

#18539

Lead Free Component on solder paste (lead) | 2 January, 2002

What are the implication of using lead free components on lead content solder paste.

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#18551

Lead Free Component on solder paste (lead) | 3 January, 2002

You're correct. There's a range of issues. Two perspectives are: * TI and other suppliers has been shipping lead-free solderability protected leads on components for years. We have discussed, here on SMTnet, a need to adjust the reflow profile to obtain adequate connections. TI has documented the acceptability of these connections. * When you alloy metals, the combination of the metals determines the reliability of the solder connection. In "Lead-Free Solder - Technology & Applications For Environmentally Friendly Manufacturing" [Electrochemical Publications 2001 ISBN 0901150401], the author, Dr JS Hwang, devotes a chapter to lead contamination of lead free solders.

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monkey

#18573

Lead Free Component on solder paste (lead) | 4 January, 2002

There are several implications: - some lead free alloys do not form an acceptable solder joint when used with lead contaning paste. (ie. Bismuth) - if you use both lead free and lead containing components, you will have different solder joint compositions on the pcb - quality would have a field day with this. - you would need to modify your reflow profile according to the vendor's specifications - an increase in temperature may cause problems with other components, also an increase in energy costs

Good luck! N

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Kris

#22440

Lead Free Component on solder paste (lead) | 19 November, 2002

does anyone have concrete data on the reliability of lead free components-SN/Bi used with tin lead paste

thanks

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#22446

Lead Free Component on solder paste (lead) | 20 November, 2002

There's a fair number of issues with lead and bismuth solder alloys: * Lead and bismuth alloys can form a eutectic composition of Bi52Pb32Sn16 in the grain boundaries. Melting point of the eutectic alloy is 95�C [~96�C?]. * Fillet lifting of PTH due to pasty range (206-213�C) * Published data seems be conficted about strength loss due to intermetaalic compounds.

You need to keep bismuth below 3% by weight.

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Kris

#22449

Lead Free Component on solder paste (lead) | 20 November, 2002

Does any body know how many US or europe based component manufacturers have decided not to use Sn/Bi on lead plating. Most of far east manufacturers seem to have selected Sn/Bi on their component finish. Intresting articles on Samsung,Epson and OKI websites about it . check if you guys are intrested

thanks

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