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June 2009

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Subject:
From:
John Burke <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, John Burke <[log in to unmask]>
Date:
Fri, 19 Jun 2009 09:28:55 -0700
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text/plain (115 lines)
I have used this process a number of times and it works. 

It is a two step etch process for the stencil manufacturer, but like I said
I have used this on similar issues about 6 - 8 years ago and had good
results.

John Burke
(408) 515 4992

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Braddock, Iain (UK)
Sent: Thursday, June 18, 2009 12:35 AM
To: [log in to unmask]
Subject: Re: [TN] SolderMask Question

One option may be that you identify in your Gerber file the areas
causing problems ie. raised  and have your solder stencil relieved on
the bottom side to allow clearance in these areas, that way the stencil
would lie flush when printing.....just a thought! 

	Iain. 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Vargas, Stephen M
Sent: 17 June 2009 17:22
To: [log in to unmask]
Subject: [TN] SolderMask Question

               *** WARNING ***

This mail has originated outside your organization, either from an
external partner or the Global Internet. 
     Keep this in mind if you answer this message. 

All:

 

We have a Class III PCB, that we are building using leaded technology
(non-RoHS), HASL finish, where my customer is specifying double masking
over vias for "via protection". Dry film is initially being placed over
the vias only, then the board is covered by LPI. Our problem is that it
creates problems with the solder stencil not properly gasketing to the
PCB during screen-printing resulting in solder defects. We are seeing
raised solder mask as high as .003". Is this (double masking)
commonplace? Are there more "manufacturing friendly" options for optimum
via protection? I've asked about possibly using dry film mask only (no
LPI on top), but was told that the mask feature sizes are too small for
dry film. Any insight would be appreciated. 

 

Regards,

Steve Vargas

 

Polaris Contract Mfg Inc


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