Chet,

There was some discussion a few months ago on Technet, you may want to
search the archives.  The thru-hole may be trickier.

Here's one post:

Subject: Re: Solder Mask Question 
From: Ahne Oosterhof <[log in to unmask]> 
Reply-To: [log in to unmask] 
Date: Fri, 25 Sep 2009 22:43:37 -0700 
Content-Type: text/plain 

You can remove the solder mask from pads using laser ablation. Check
with
Bob Dervaes of A-Laser (503-641-9428). To reduce the thickness is a
rather
tricky thing with unpredictable results.

Have fun,
Ahne. 


Regards,
Mike
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Harner, Chester
Sent: Monday, February 22, 2010 1:14 PM
To: [log in to unmask]
Subject: [TN] Removal of Solder Mask from CU pads

IPC7711 provides methods for removal of "Conformal Coating" and epoxy
coating is included in the discussion. However, could it apply to the
removal of epoxy solder mask?

 

I have some boards that made it into pick and place with a few SMT pads
covered with solder mask, and four through hole components with no
solder mask openings around the pads. It wasn't discovered till the SMT
parts (0603 caps) fell off the assembly and the through hole diodes
would not solder.

 

The Question - Is there a way to remove the solder mask from the pads
and still meet IPC-600/610 requirements.

 

Chet Harner   Sr. Engineer   Crane Hydro-AirePO Box 7722 Burbank Ca -
91510  818-526-2600 x3557

 


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