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Removing Green Masking on PCB's

plopez

#6874

Removing Green Masking on PCB's | 14 June, 2001

Hello.

We are a contract manufacturer that requires the removal of the green making layer on a PCB board. What we need to do is expose some of the conductive trace (estimated .025 length) to create a solder joint to a SMD. It sounds ridiculous, but were asked to do so. What my question is, does anyone know of a solution that'll remove the green masking layer? I'd like to avoid scraping process. Your response would really be appreicated.

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#6896

Removing Green Masking on PCB's | 14 June, 2001

See, now you know how you got the job!!! ;-)

Assuming you mean solder mask, that stuff is designed to be tough to remove. It�s an epoxy meant to protect the board features from the ravages of board fabrication and everyday life. Your choices are: * Chemicals [unfortunately any chemical aggressive enough to remove the mask will also go a long ways towards destroying the board. Tough sell to most customers. Umm, umm] * Mechanical [tried it don�t like it, but then again, with the choices yagot, X-Acto knives and Drummel tools might not be so bad � ] * Microblasting [ But, be aware of potential ESD problems. And can be a bit messy. So, you�ll be running a ground wire and other utilities out to the picnic bench out back.]

IPC-7721 [http://www.ipc.org] covers microblasting as a method for removing solder mask. Look also at: http://www.circuittechctr.com/guides/2-3-6.htm [Thanks to Denny Ferry and Circuit Technology Center, Inc. 45 Research Drive, Haverhill, MA 01832 978-374-5000 � Fax: 978-372-5700 for posting this great repair guide.] On the ESD thing, look at: http://epims.gsfc.nasa.gov/tva/Pkggen/Coatings/microabr.htm.

If it�s not solder mask, but some other coating, root around the above Circuit Technology link for some tips on removing other coating materials.

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CPI

#6915

Removing Green Masking on PCB's | 15 June, 2001

Are you exposing so you can solder and SMD component directly to it? If not are there ant vias near by that connect to the area you are trying to expose? If not I have done as Dave suggested using a dremal tool. Messy but it works.

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