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PB-FREE Spec for PCBs

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aj

#50312

PB-FREE Spec for PCBs | 21 May, 2007

Hi all,

Can anyone share the revised spec that they now recommend for PB-FREE Processing ?

I have been told to request High TG rating ? should this suffice.

any replies appreciated.

aj...

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#50313

PB-FREE Spec for PCBs | 21 May, 2007

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

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#50314

PB-FREE Spec for PCBs | 21 May, 2007

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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#50365

PB-FREE Spec for PCBs | 24 May, 2007

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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#50407

PB-FREE Spec for PCBs | 28 May, 2007

Boundary Scan

Used PCB Equipment - ECM