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| Reply To: | TechNet E-Mail Forum. |
| Date: | Wed, 26 Apr 2000 13:03:42 -0700 |
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Chemical removal in a specific shape will be difficult to achieve even if
you can get ahold of the chemical to locally dissolve the soldermask (20
years ago, I used methylene chloride, but this is no longer considered safe).
Mechanical methods are currently used with varying results.
Grinding with a dremel tool works on bare boards but it is poorly
controlled and might abrade into the copper to far.
My preferred mechanical method is to use a microsandblaster, walnut shells,
and a piece of a stainless steel stencil corresponding to the shape needed.
It works great but you have to own a microblaster unfortunately.
Most likely, the method you should use is to lightly scrape with a
soldering iron tip shaped like a chisel. The soldermask will soften with
heat and at that point, it can be pushed aside provided there is copper
below it. If you don't want to tin the copper below, however, this might
also not work for you.
Phil
At 12:38 PM 4/26/00 -0700, Larry W. Burgess wrote:
>Ivan,
>
>One method is to use a laser for this Soldermask removal. I have done it
>several time recently for smaller areas where we used a mask made from thin
>core copper.
>
>Larry
>
>----- Original Message -----
>From: Ivan Barrios <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: Wednesday, April 26, 2000 12:14
>Subject: [TN] Removal of Solder mask
>
>
>> We need to remove a small area (0.120" x 0.100") of soldermask from the top
>> layer, without removing any of the copper underneath. Is there a chemical
>> used to "etch" out this soldermask, and not compromise the copper layer
>> underneath? As always, your responses are most welcome
>>
>> Ivan Barrios
>>
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