Hi David,

Indeed, PCBs need to be consideredsomething like MSL 2 or 2a; thicker PCBs more like MSL 3 or worse.

Also, for lead-free the MSL levels for both components and PCBs drop at least one level.

Werner


-----Original Message-----
From: David Tremmel <[log in to unmask]>
To: [log in to unmask]
Sent: Sat, 16 Feb 2008 5:55 pm
Subject: [TN] 'MSL' of PCBs




Hello TechNet Gurus,
 
 
If there any of you out there that have to do BGA or large QFP rework on
lass 2 assemblies at lead free temperatures, what general rule do you
ollow to bake the moisture out of the board?
 
Even if the component has an MSL of 2a, 2 or 1, that does not mean that the
CB does not have an equivalent MSL so to speak.  I generally shoot for 8
ours at 105°C but sometimes in a pinch will shorten it to 4 hours at 105°C
or a standard 1.0 mm (or so) PCB.
 
I am sure that 'it depends' will come up but I was wondering if I should
onsider the board itself as a 'BGA' with an MSL of 2a or 2.
 
 
If anyone would like to share their experience, I thank you in advance.
 
 
Thank you,
 
David Tremmel
847 858-5540 - Cell
847 557-9574 - Office
847 557-9573 - Fax
 

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