>----------------------------------------------------- I encountered a similar problem with a previous employer some years ago. I procured some basic paint stripper from a major home repair retailer. It was the the "super thick" formulation. I masked-off the to-be-stripped area with kapton tape (masked slightly undersized, as I recall, as some stripper will inevitably sneak under the tape). Applied the stripper sparingly with a swab or other suitable applicator. Observed the LPI, and when it began to bubble/blister, easily removed the softened mask with a swab. I remember approx. 5-10 minutes for the stripper to do its job. Stubborn bits may require a poke with an orange stick, toothpick, etc. Really stubborn bits, or especially thick coatings, may require a second stripper application. Generously cleaned & rinsed the area with IPA and DI. Dried & tinned the exposed copper plane. Of course, this was all done in a properly ventilated area, wearing all pertinent safety gear. This worked quite well, as an engineering-controlled process. Hope this helps. => ells >--------------------------------------------------- On Wed, 30 Mar 2005 13:42:27 -0600, Genny Gibbard <[log in to unmask]> wrote: >Another thing along the same lines - but doesn't do it as neat as what you >did, Steve, is apply some solder to some solder wick and rub the solderwick >back and forth on the board, using a soldering iron - removes mask and tins >the underlying copper in one step... > >Similar to Ramon's suggestion - heat is applied, and the abrasiveness of the >wick scrapes the soldermask off, but might be slightly less abusive to the >iron tip than the suggestion below. > >-----Original Message----- >From: Dehoyos, Ramon [mailto:[log in to unmask]] >Sent: 30-Mar-05 1:17 PM >To: [log in to unmask] >Subject: Re: [TN] Selective LPI soldermask removal... > > > Hi Steve: > I have used on green LPI, a heat gun and a somewhat >sharp wide solder iron tip. Move the heat around the area and scrap the >masking with the tip. It comes off very fast. > Regards, > Ramon > >-----Original Message----- >From: TechNet [mailto:[log in to unmask]]On Behalf Of Stephen Gregory >Sent: Wednesday, March 30, 2005 1:59 PM >To: [log in to unmask] >Subject: Re: [TN] Selective LPI soldermask removal... > > >I messed up the URL in my email, some may have figured that >out. But it's: http://www.stevezeva.homestead.com > > >Kind regards, > >-Steve Gregory- >Senior Process Engineer >LaBarge Incorporated >Tulsa, Oklahoma >(918) 459-2285 >(918) 459-2350 FAX > > >|---------+-----------------------------> >| | Jeffrey Bush | >| | <Jeffrey.Bush@VTCI| >| | RCUITS.COM> | >| | Sent by: TechNet | >| | <[log in to unmask]> | >| | | >| | | >| | 03/30/2005 12:39 | >| | PM | >| | Please respond to | >| | TechNet E-Mail | >| | Forum; Please | >| | respond to Jeffrey| >| | Bush | >| | | >|---------+-----------------------------> > >>--------------------------------------------------------------------------- >-----------------------------------| > | >| > | To: [log in to unmask] >| > | cc: >| > | Subject: Re: [TN] Selective LPI soldermask removal... >| > >>--------------------------------------------------------------------------- >-----------------------------------| > > > > >We could do this for you with laser. > >Jeffrey Bush >Director, Quality Assurance and Technical Support > >VERMONT CIRCUITS INCORPORATED > 76 Technology Drive - POB 1890 > Brattleboro, Vermont 05302 > Voice: 802.257.4571.21 Fax: 802.257.0011 > http://www.vtcircuits.com > > >-----Original Message----- >From: Stephen Gregory [mailto:[log in to unmask]] >Sent: Wednesday, March 30, 2005 12:25 PM >To: [log in to unmask] >Subject: [TN] Selective LPI soldermask removal... > >Happy "Hump-day"! > >I might have asked the list about this over a year ago, I can't >remember. >But I have this >assembly that goes into a Radar system. There's a device on the assembly >that has to >be sitting over the metal of the top layer plane, with no solder mask on >the board beneath >the footprint of the device for it to work properly. Unfortunately, the >solder mask file in the >gerbers didn't reflect this. So at the time (over a year ago), I >reworked >the boards that we >had to correct the problem...and let me tell you, it's a REAL PIA! > >Go to: http://www.stevzeva.homestead.com and look at "Mask Removal", and >"After Tinning" >to see what I'm trying to do. > >I did this over a year ago, and we got an order for these assemblies >again...but the gerber never >got corrected, and I get to do this again. WHOOPEE! > >I have to remove the solder mask beneath where the device is going to be >installed, and then >I solder coat the area to cover the exposed copper. I'm removing the >solder >mask very, very >carefully with a Dremel and a very fine abrasive tip, and I'm using an >exacto knife with various >blades. This is all being done tediously under a microscope to prevent >the >copper from being >removed from the plane. We have a micro-blaster here to remove conformal >coating, but it can't >get down to the bare copper. That's why I'm using the Dremel and exacto >knife. This time when >the board house did their micro-etch or pumice scrub just prior to >applying >the solder mask, they >really did a good job! That mask is on there, and meant to stay put! I'm >really having a hell of a >time doing this on these latest fabs. > >Is there any other way to remove this coating in the area that I need >to? >I'm thinking maybe a >laser. Does anybody know where I would go to get this done, and about >what >it would cost? >There's only 5-boards that I need this done to, but it takes me a couple >of >hours with each board >to complete the job. > >Kind regards, > >-Steve Gregory- >Senior Process Engineer >LaBarge Incorporated >Tulsa, Oklahoma >(918) 459-2285 >(918) 459-2350 FAX >__________________________________________________________________ >This message may contain information that is privileged and confidential >to >LaBarge, Inc. It is for use only by the individual or entity named >above. >If you are not the intended recipient, you may not copy, use or deliver >this message to anyone. In such event, you should destroy the message >and >kindly notify the sender by reply e-mail. > >--------------------------------------------------- >Technet Mail List provided as a service by IPC using LISTSERV 1.8e >To unsubscribe, send a message to [log in to unmask] with following text >in >the BODY (NOT the subject field): SIGNOFF Technet >To temporarily halt or (re-start) delivery of Technet send e-mail to >[log in to unmask]: SET Technet NOMAIL or (MAIL) >To receive ONE mailing per day of all the posts: send e-mail to >[log in to unmask]: SET Technet Digest >Search the archives of previous posts at: >http://listserv.ipc.org/archives >Please visit IPC web site >http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional >information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 >ext.2815 >----------------------------------------------------- > >--------------------------------------------------- >Technet Mail List provided as a service by IPC using LISTSERV 1.8e >To unsubscribe, send a message to [log in to unmask] with following text in >the BODY (NOT the subject field): SIGNOFF Technet >To temporarily halt or (re-start) delivery of Technet send e-mail to >[log in to unmask]: SET Technet NOMAIL or (MAIL) >To receive ONE mailing per day of all the posts: send e-mail to >[log in to unmask]: SET Technet Digest >Search the archives of previous posts at: http://listserv.ipc.org/archives >Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 >for additional information, or contact Keach Sasamori at [log in to unmask] or >847-615-7100 ext.2815 >----------------------------------------------------- > > > > >__________________________________________________________________ >This message may contain information that is privileged and confidential to >LaBarge, Inc. It is for use only by the individual or entity named above. >If you are not the intended recipient, you may not copy, use or deliver >this message to anyone. In such event, you should destroy the message and >kindly notify the sender by reply e-mail. > >--------------------------------------------------- >Technet Mail List provided as a service by IPC using LISTSERV 1.8e >To unsubscribe, send a message to [log in to unmask] with following text in >the BODY (NOT the subject field): SIGNOFF Technet >To temporarily halt or (re-start) delivery of Technet send e-mail to >[log in to unmask]: SET Technet NOMAIL or (MAIL) >To receive ONE mailing per day of all the posts: send e-mail to >[log in to unmask]: SET Technet Digest >Search the archives of previous posts at: http://listserv.ipc.org/archives >Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 >for additional information, or contact Keach Sasamori at [log in to unmask] or >847-615-7100 ext.2815 >----------------------------------------------------- > >--------------------------------------------------- >Technet Mail List provided as a service by IPC using LISTSERV 1.8e >To unsubscribe, send a message to [log in to unmask] with following text in >the BODY (NOT the subject field): SIGNOFF Technet >To temporarily halt or (re-start) delivery of Technet send e-mail to >[log in to unmask]: SET Technet NOMAIL or (MAIL) >To receive ONE mailing per day of all the posts: send e-mail to >[log in to unmask]: SET Technet Digest >Search the archives of previous posts at: http://listserv.ipc.org/archives >Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 >for additional information, or contact Keach Sasamori at [log in to unmask] or >847-615-7100 ext.2815 >----------------------------------------------------- > >--------------------------------------------------- >Technet Mail List provided as a service by IPC using LISTSERV 1.8e >To unsubscribe, send a message to [log in to unmask] with following text in >the BODY (NOT the subject field): SIGNOFF Technet >To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) >To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest >Search the archives of previous posts at: http://listserv.ipc.org/archives >Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------