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 solder

Views: 3502

#60484

Lead Free solder | 19 November, 2009

Can anyone tell me if there is a volume difference between a pound of lead vs. lead free solder? Does lead free solder attack stainless or castiron when it's not molten? Thanks.

Jay

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#60496

Lead Free solder | 19 November, 2009

Density. There is a difference between lead (.410 lbs. per cubic inch) and tin (.254 lbs. per cubic inch). The same volume of tin-based solder, therefore, weighs approximately 1/4 less than a lead-based material. This adds up to more joints per pound of solder. Cost calculations should include the effect of density and the advantages of a lower weight product. [Fry Metals]

Liquid tin is very corrosive. It will make most metals run home to their mama crying like little school-girls after getting their lunch money taken by a bad girl with a mustache.

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#60517

Lead Free solder | 21 November, 2009

In addition to Dave’s response Yes tin dissolves (corrodes) other metals even at room temperature, just a whole lot slower. The affinity of tin to dissolve other metals is most effectively neutralized with the addition of lead.

It is not by accident that lead has been used in soft soldering for a half a century.

Nuff said

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#60519

Lead Free solder | 21 November, 2009

Isn't it more like 20 centuries, at least? 8-)

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#60520

Lead Free solder | 21 November, 2009

You are technically correct eutectic Sn/Pb was discovered by the ancient Egyptians in (XXX) BC much longer then 20 centuries.

I was just referring to soft soldering in the electronics assembly industry :-).

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#60521

Lead Free solder | 21 November, 2009

There is evidence of lead being used in soldering 5000 years ago in Mesopotamia.

Not a big issue for most people doing SMT but the poster should also understand why percent metal is adjusted for different solder paste alloys. You print by volume but purchase solder paste by weight. A volume X of 80/20 Au/Sn paste is heavier than volume X of 63/37 Sn/Pb paste of equal percent metal content by weight. Thus you need to increase metal percent by weight of solder pastes with a higher density than the paste used previous. If you don't do this, your solder joints will have lower volume.

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#60549

Lead Free solder | 24 November, 2009

Some companies claimed their lead free solders wouldnt attack stainless steel, frankly they do and they should not be allowed to get away with these claims. Lead Free does not attack Cast iron

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#60569

Lead Free solder | 27 November, 2009

Would i be able to use the cast iron pot from my electrovert with out any problems? I thought the tin would dissolve the iron in the pot? This lead free thing is a headache!

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