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

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SMT electronics assembly manufacturing forum.


Sn43Pb43Bi14 Solder

Gary Bremer

#20657

Sn43Pb43Bi14 Solder | 12 July, 2002

Does anyone have experience using Sn43Pb43Bi14 solder on high performance circuit boards that are subjected to temperatures from -55� Celsius to +85� Celsius and vibration requirments at 6g? What companies/industries do you know that are using this solder?

Thanks

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#20727

Sn43Pb43Bi14 Solder | 16 July, 2002

We don't use Sn43Pb43Bi14 solder.

We don't make high performance circuit boards that are subjected to temperatures from -55� Celsius to +85� Celsius and vibration requirments at 6g.

We don't like bismuth solder alloys, because: * 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 [Bi52Pb32Sn16] is 95�C. * Overall result is a large decrease in the strength of the joint. * Fillet lifting of PTH due to pasty range * Avoid any lead!!

We don't like Sn43Pb43Bi14 solder, because: * Very wide [~35�F] pasty range. * Bismuth naturally makes it low temperature [~50�F lower liquidus] than what we're used to using. * Lower temperature liquidous temperature lowers service temperature to ~160�F, a little lower than you 85�C. [without considering effect of eutectic alloy - Bi52Pb32Sn16].

While you are waiting for other replies here on SMTnet, consider contacting Sn43Pb43Bi14 solder suppliers [ie, Kester, Promosol, Sasaki, etc] and asking: * Their technical sales types for more information. * For a list of contacts at customers that use Sn43Pb43Bi14 solder.

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