Hi,

just confirm Soldering Temperature Impact Index  > 215 for lead free, not only Tg.

STII = (Tg+Td)/2 - (CTE z below Tg*(Tg-50)+ CTE z below Tg *(260-Tg)) * 10

Best Regards

KRISTRONICS GmbH

Dipl.Ing. (FH) Torsten Hagge
team leader HW development  
Gewerbegrund 5-9
24955 Harrislee
Telefon +49 (0) 461 7741-624
Telefax +49 (0) 461 7741-642
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www.kristronics.de
Place of jurisdiction: Flensburg, commercial register: HRB 1433 FL
CEO Dipl.-Ing. oec. Thormod Ohm
VAD-Id DE 811182059
Bank account: Deutsche Bank AG Flensburg, account 4216610, bank number 21570011
IBAN: DE32 2157 0011 0421 6610 00, BIC: DEUT DE HH 215
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-----Ursprüngliche Nachricht-----
Von: TechNet [mailto:[log in to unmask]] Im Auftrag von James Head
Gesendet: Mittwoch, 13. April 2016 16:25
An: [log in to unmask]
Betreff: Re: [TN] Material Tg for RoHS

For RoHS compliant PCBs we were advised that the T(288), rather than the Tg, was a more appropriate figure to specify, but that a Tg greater than 140C should be suitable. After consulting with a couple of PCB fabricators we specify boards thus:

"Laminate: Tg > or = 140C, T(288) > 5 minutes"

We also have state on the fabrication drawing "RoHS COMPLIANT This is a RoHS compliant product. Use only RoHS compliant PCB materials".

Having said that, our particular product range has a deferral before it needs to become RoHS compliant but we've been endeavouring to meet the requirements wherever possible since just before 2013.

Regards,

James

James Head BEng CID+ MIIE MIET 
Senior PCB CAD Engineer
Crowcon Detection Instruments Limited
172 Brook Drive
Milton Park
OX14 4SD
Telephone: +44 (1235) 557700 ext. 7885
E-mail: [log in to unmask]





-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
Sent: 13 April 2016 15:09
To: [log in to unmask]
Subject: [TN] Material Tg for RoHS

Way back when we were making changes to meet RoHS requirements, we were advised to use bare board materials with 170 Tg or higher. So we changed our Fabrication Drawing Notes and everything has been fine.

But recently I've noticed that the default material for several different suppliers is around 155 Tg. Has the thinking "relaxed" in this regard? Or should I stick with my 170 ?

Jack


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