I suspect a lot since all of the work on solderability/reliability in regard
to wetting angles was done many years ago.
Is Werner on the forum?
John
John Burke
(408) 515 4992
-----Original Message-----
From: Paymon Sani [mailto:[log in to unmask]]
Sent: Friday, March 30, 2007 10:15 AM
To: TechNet E-Mail Forum; John Burke
Subject: RE: [TN] Solder Resist Encroachment onto BGA pads
Thank you John, is there any studies on this?
Paymon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Burke
Sent: March 30, 2007 12:45 PM
To: [log in to unmask]
Subject: Re: [TN] Solder Resist Encroachment onto BGA pads
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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