Actually, Revision E of SM-840 is the current one.
Doug Pauls
From: "Amol Kane (Asteelflash,US)" <[log in to unmask]>
To: <[log in to unmask]>
Date: 02/07/2012 12:36 PM
Subject: Re: [TN] Soldermask adhesion test
Sent by: TechNet <[log in to unmask]>
I think so too. I am trying to get my hands on the IPC-SM-840C standard
to read in detail. Thank you for the excerpt from IPC-610
Regards,
Amol
-----Original Message-----
From: Guy Ramsey [mailto:[log in to unmask]]
Sent: Tuesday, February 07, 2012 1:28 PM
To: 'TechNet E-Mail Forum'; Amol Kane (Asteelflash,US)
Subject: RE: [TN] Soldermask adhesion test
IPC-A-610E
10.7 Solder Mask Coating: This section covers the acceptability
requirement
for solder mask coatings on electronic assemblies after assembly.
Additional information on solder mask is available in IPC-SM-840.
10.7.2
During solder assembly operation, the mask prevents solder bridging.
Blistering and loose particles of solder mask material are acceptable
after
the completion of the assembly provided they will not affect other
functions
in the assembly.
Process Indictor - Class 2,3
Blisters / flaking expose base conductor material.
Defect - Class 2, 3
Coating blisters / scratches / voids allow film to flake in critical
assemblies after a tape test.
Solder fluxes, oil or cleaning agents are trapped under coating.
So, not really sure how to distinguish the difference between the PI and
Defect condition.
Let's presume your condition is a Defect. Does the defect condition
suggest
a problem with the board or the assembly processing? My experience
suggest,
a board fabrication problem. Really, the mask should stick to the
copper.
However, J-STD-001, IPC-A-610, IPC-6012 and IPC-A-600 are not
troubleshooting tools. They will not point you back to the supplier.
Guy
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Amol Kane
(Asteelflash,US)
Sent: Tuesday, February 07, 2012 9:59 AM
To: [log in to unmask]
Subject: [TN] Soldermask adhesion test
Dear Technetters,
We have soldermask flaking off from the traces on a PWB after the wave
process (LF NC process). The same date code in stock passes the tape
test per IPC-TM-650 Test Method 2.4.28.1. For non melting materials (Cu
traces), is there another test I can do after assembly to test adhesion
of the mask? If the board fails the tape test after assembly, is that a
valid use of the test method to reject the bare board? The boards in
stock are over a year old (in dry pack condition), but moisture or age
should not affect the function of correctly processed soldermask, should
it?
My take is that Soldermask applied to a clean Cu substrate and fully
cured should not flake off even after assembly, but I am searching for a
standard or a clause I can use.
Thanks,
Amol
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