Perhaps if the vendor is not the party at fault?
In a previous life I had to do a smallish change on a telephone line
switch. My boss did not want to invest the time for a full design
review on the PCB since it was just a small change, despite the fact the
neither myself or the designer were familiar with the design (it was
done out of house by a contractor), the software the PCB was done in, or
the original drawing package.
At risk buy, 5,000 pcb's, from a local (local is ALWAYS better, right?)
board house. Soldermask and silkscreen all over the board. The
original designer decided not to use the default layers but some weird
combination of note and fab layers for the mask and screen
3 weeks later, management finally decided to scrap the lot after a poor
tech spent 120 hours with a dremel tool and various solvents.
-----Original Message-----
From: Stadem, Richard D. [mailto:[log in to unmask]]
Sent: Wednesday, August 29, 2007 7:18 AM
Subject: Re: Solder Mask Solvent?
Why would anyone use any of these methods (laser ablation, burning away
with solder iron, etc.) to remove extraneous solder mask over the pads?
Any method used to remove soldermask from the pads is going to
compromise the solderability and reliability of the assembly.
Simply return the PWBs to the vendor and tell them they do not comply
with IPC standards. Demand a new lot of boards, and tell them to do it
right next time.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Paul Edwards
Sent: Tuesday, August 28, 2007 2:17 PM
To: [log in to unmask]
Subject: Re: [TN] Solder Mask Solvent?
Tim,
Try cranking up the heat on your Pb-free soldering iron and gently
rubbing the solder mask from the area on top of the Cu pads... The
solder mask adhesion to the Cu as well as the solder mask should start
breaking down... Be careful because the heat will also cause the
adhesive holding the Cu pad to the laminate to weaken...Once you get the
hang of it you can do this all day.... We sometimes have to... Oh, say
good bye to the tip or designate it your "solder mask scrapping" tip
Paul
Paul Edwards
Process/Quality Engineering
[log in to unmask]
Tel: 408-433-4700
FAX: 408-433-9988
Surface Art Engineering
81Bonaventura Dr.
San Jose, CA 95134
DUNS: 944740570
CAGE/NCAGE: 1XZ48
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tim Mack
Sent: Tuesday, August 28, 2007 11:25 AM
To: [log in to unmask]
Subject: [TN] Solder Mask Solvent?
All,
I have run into an issue with a board that has solder mask covering some
pads. Is there a product/solvent that can remove the solder mask easily
with out etching the copper? I would rather chemically remove it than
manually scrap it off with a razor blade.
Thanks in advance,
Tim Mack
Research Engineer
NDSU CNSE
www.ndsu.edu/cnse
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