Could it be a peel able mask - used on selective coatings

-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Mike Hill
Sent: Monday, December 05, 2011 10:21 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Solder mask cure on SMDs

Chris,

Usually gummy is tape adhesive not mask.   It might even have blue tent
from the mask.

Are you sure it's mask?

Mike Hill

-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Chris
Mahanna
Sent: Monday, December 05, 2011 9:29 AM
To: [log in to unmask]
Subject: [IPC-600-6012] Solder mask cure on SMDs

Hello all,
A customer has 1.0mm BGA SMD lands with gummy mask and ~0.4%
solderability skips when edge dip tested.
By skip, I mean all surrounding lands solder beautifully, while the
subject land takes no solder at all.
By gummy, I mean that pushing with hypodermic needle yields piled-up
mask, not chipping mask.  Away from the SMD area, we get chipping mask.

Finish is ENIG, mask is BLUE.

I'm looking for comments on root cause, and maybe how to cost
effectively collect more evidence.

We've got bitten by the uncertainty of FTIR testing before.
Differential solubility in mask stripper?

Thanks a million,
Chris

Chris Mahanna
Robisan Laboratory Inc.
317-353-6249


______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud
service.
For more information please contact helpdesk at x2960 or
[log in to unmask]
______________________________________________________________________

This communication is for use by the intended recipient(s) only and may
contain information that is privileged, confidential, proprietary and
exempt from disclosure under applicable law.  You are hereby notified
that any dissemination, distribution, forwarding or copying hereof is
strictly prohibited without the express written consent of DDi.  If you
have received this communication in error or are not the intended
recipient, you should destroy the message and any attachments or copies,
and you are prohibited from retaining, distributing, disclosing, or
using any information contained herein.  Please inform us of the
erroneous delivery by return e-mail. Thank you for your cooperation.

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud
service.
For more information please contact helpdesk at x2960 or
[log in to unmask]
______________________________________________________________________

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________