PB-FREE Spec for PCBs

Higher Tg (180) and possibly thicker board material for the larger ones if you have them...

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For more on Tg, look here: http://www.smtnet.com/Forums/Index.cfm?CFApp=1&Message_ID=32422

Also, search the fine SMTnet Archives for Td or Decomposition Temperature (the temperature that the epoxy actualy starts to break down). For instance: http://www.smtnet.com/forums/Index.cfm?CFApp=1&Message_ID=39471

In his courses, W Engelmaier urges the use on 4101 laminate slash sheets of a Soldering Temperature Impact Index, STII, to address the effects of Tg, Td & TE (thermal expansion), which are independent of each other, where: STII = (Tg+Td)/2 - [% thermal expansion 50 to 260*C]x10. For LF PCB with thickness of 0.06 inches (1.5 mm) or more, he would specify a STII>=215. Look here: http://www.trafalgar2.com/content/view/1184/106/

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Hi Aj,

We like it called out like this.

Nelco 4000-29 or equivalent lead free assembly capable material Min. 170 tg. / 340 td.

We like to have the OEM or CM call out thier prefered material first and then the equivalent notation afterwards to cover thier offshore manufactures that do not use standard state side material> (ISOLA/Nelco) they would typically use Iteq, TUC or Nanya.

Regards,

Board House

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You can refer to this link. http://www.merix.com/files/Lead%20Free%20Material%20Tech%20Bulletin%20Rev%20C.pdf

Hope this will help.

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