Actually yes.

If you put solder resist over the lands for the BGA you have by definition a
joint defined by the resist system.

Effectively this will give you a 90 degree wetting angle which is - you
guessed it a stress riser.

So a joint with solder mask defined joints will be more liable to crack
under stress.

John
 
 
John Burke
 
(408) 515 4992

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Paymon Sani
Sent: Friday, March 30, 2007 9:02 AM
To: [log in to unmask]
Subject: [TN] Solder Resist Encroachment onto BGA pads

Hello All,

 

Does anybody know why IPC does not allow any solder resist encroachment
onto the BGA copper defined lands for PCBs?


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