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


______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________