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HMP Lead free solder?

Views: 2058

Slaine

#36421

HMP Lead free solder? | 31 August, 2005

I have a through hole product that is currently built with HMP solder(93.5Pb,5Sn,Ag1.5). We then dip it in 60/40 SnPb to give a solderable finish as HMP tends to oxidise. We need the HMP as our Customers solder through reflow ovens. Some customers want to change to SAC alloys and a RoHS complient product. Although HMP is RoHS complient on its own, if you dip it in a SAC alloy to give it a solderable finish the SAC will alloy with the HMP to give a non-RoHS complient finish. I cant find another HMP solder thats lead free except high Au,Cd or Zn which are undesiarable. One thought we had was to dip in an OSP. Any recomendiation where i can get an OSP for this application.

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dougs

#36423

HMP Lead free solder? | 31 August, 2005

i must be missing something, the HMP has 93.5% lead content but is RoHS compliant? How does that work?

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Slaine

#36424

HMP Lead free solder? | 31 August, 2005

if a solder has over 85% lead its classed as RoHS complient because its difficult to achive the same melting point with anything else (298degrees). a few other alloys with a similar range are ; % % 266E266 82.6 Cd 17.4 Zn 271MP 100 Bi 280E280 80 Au 20 Sn 382E382 95 Zn 5 Al none of which are anywhere near acceptable 82%cad speaks for its self, 100%Bisimuth (it soft and if it mixes with lead at the customer the PbBi metls at 110degrees our products are spec'd to 125. 80%gold, er no, and 95% zinc gives off zinc oxide. So its classed as complient, but if its then soldered to with SAC its less than 85% lead and thus non complient.

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dougs

#36450

HMP Lead free solder? | 1 September, 2005

learn something everyday, thanks for the explanation.

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Clampron

#36458

HMP Lead free solder? | 1 September, 2005

Hi Slaine,

Actually, HMP Leaded solder is not complient, it is exempt only when the specific application requires this temp.

Sorry for the intrusion but I am working on something very similar currently.

Thanks

Chris

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James

#36469

HMP Lead free solder? | 1 September, 2005

What is the total Pb after dip? If it is above 85% you should still be fine as you have created a homogenous material.

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