Hullo Somtawan,
Is is all over the board or just around a specific component? It seems that
possibly your paste was contaminated with water or some solvent. If a
no-clean flux was used, then IPA and/or deionised-water will only worsen the
colour - the white is the discolouration of the flux residue still on the
boards when mixedf with IPA/solvent. Not sure in your instance, but it could
just be cosmetic or if the board is to be coated, then you may have adhesion
problems. Also not sure what method of cleaning was used, but if you really
need to get this off, then only mechanical (brush, agitation) is required,
then a deionised rinse afterwards may help. Which solder brand did you use?
With respect to IPC-610 criteria, white carbonates and contaminates may be
acceptable, but only at the discretion of the customer/designer.
Regards
-----Original Message-----
From: Somtawin Pornpottanamas [mailto:[log in to unmask]]
Sent: Thursday, March 18, 2004 12:15 PM
To: [log in to unmask]
Subject: [TN] White residue
Has anyone ever seen white contaminate ( like a crystal) on assembly
boards , between IC lead? I found white residue on some board after
reflow . I try to clean by used IPA, flux removal solvent and also DI
water. But could not remove it. I also found that after we used the
solvent to clean, the white residue increase more.
Our process used no clean . What is this residue? What type of solvent
that should be use to clean flux residue when we have to rework or
Dedug?
Thanks & Regards,
Somtawin Pornpottanamas
Material Engineer
Kimball Electronics (Thailand)
Tel. 038-401566 ext. 211
Fax. 038-495029
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