Be nice to figure out what caused the cracking, since that would give an indication as to whether the underlying laminate is at risk.
But solder mask's job is to prevent solder wetting, and a cracked mask can still do a fine job with that. Matter of fact, I often don't even put mask down in places which don't need it to block solder flow (like across a dielectric which won't wet anyway). Solder mask is not intended as an electrical insulator (yes, I wear that t-shirt regularly).
If the cracks mean that the soldermask is poorly cured or poorly adhered, then it probably won't block solder well, so it may be no good. But your pictures are of reflowed boards, so who really cares whether it has mask covering dielectric or not?
Moisture ingress blocking has been brought up, but I doubt soldermasks, which are typically loaded with completely acceptable pinholes AND have generous clearances around pads, are much use there anyway.
Wayne Thayer
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey
Sent: Thursday, March 22, 2012 12:04 PM
To: [log in to unmask]
Subject: Re: [TN] EXTERNAL: [TN] Acceptability of Cracked Solder Mask
You looking at pate 10-46 in revE?
Cracking of Solder mask: A1, A2, D3.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gumpert, Ben
Sent: Wednesday, March 21, 2012 3:39 PM
To: [log in to unmask]
Subject: Re: [TN] EXTERNAL: [TN] Acceptability of Cracked Solder Mask
Bill,
Looking again at your images, you could say that the cracks don't actually
bridge non-common circuits since you have non-solder mask defined pads - the
crack ends before it reaches another circuit.
Ben
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gumpert, Ben
Sent: Wednesday, March 21, 2012 3:30 PM
To: [log in to unmask]
Subject: Re: [TN] EXTERNAL: [TN] Acceptability of Cracked Solder Mask
Bill,
I see the confusion; 610 mentions a target condition for cracks, but then
doesn't follow up with an acceptable or defect condition for cracks.
But later in the document, a solder mask scratch that bridges non-common
circuits is indicated as a defect for all classes, so I would have to say a
crack bridging non-common circuits is also a defect for all classes.
Ben
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of William Clark
Sent: Wednesday, March 21, 2012 3:03 PM
To: [log in to unmask]
Subject: EXTERNAL: [TN] Acceptability of Cracked Solder Mask
It is not clear to me from IPC 610-E if a crack in a solder mask constitutes
a Class 1 or Class 2 defect. Pictures of the typical cracks we are seeing
are at the link below. The crack in picture 3 repeats at the same feature
on every board in the array. The cracks were not visible on the bare board
and the boards passed the tape test. I'm looking for input on the
suitability of these boards.
Thanks
Bill
http://s1066.photobucket.com/albums/u408/clarkerg/
Bill Clark
Manufacturing Engineering and Quality Manager
ERG, <http://www.ergpower.com/> Inc. 2601 Wayne Street, Endicott, NY
13760
607-754-9187
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