Les_Garten Posted November 5, 2009 Report Posted November 5, 2009 I just got a PCB that has a void in the solder mask on top of the board. It is not a scratch, the mask is kinda piled up around the void. It looks like a contaminant may have kept the mask off that area. There are some epoxies online to fix this. I was wondering if you guys know of something locally obtainable to fix this?
luvdunhill Posted November 5, 2009 Report Posted November 5, 2009 I just got a PCB that has a void in the solder mask on top of the board. It is not a scratch, the mask is kinda piled up around the void. It looks like a contaminant may have kept the mask off that area. There are some epoxies online to fix this. I was wondering if you guys know of something locally obtainable to fix this? finger nail polish, or uber-cryo-milspec conformal coating (conveniently available at Fry's)
guzziguy Posted November 5, 2009 Report Posted November 5, 2009 You can use the "Singlepower method", which is to solder a paper clip across the void.
Les_Garten Posted November 5, 2009 Author Report Posted November 5, 2009 finger nail polish, or uber-cryo-milspec conformal coating (conveniently available at Fry's) There are some Solder mask epoxies, but the price is high. Fingernail polish doesn't seem like it would resist temp very well?
Les_Garten Posted November 5, 2009 Author Report Posted November 5, 2009 You can use the "Singlepower method", which is to solder a paper clip across the void. My problem is the opposite. The missing mask exposes the ground plane. I'm trying to seal it up. It's within about 3mm of an output pad on an amp board. Seems my options are to ignore and be careful around it, or try to seal it with something resistant to high temp. Hmmm, what is the voltage carrying capability and resistance of a paper clip. Can't honestly say that solution hasn't crossed my mind n the past. I have a call into Loktite to see if they have a high temp epoxy that is reasonably priced.
Pars Posted November 5, 2009 Report Posted November 5, 2009 Can you send the PCB back as defective? Conformal coatings are usually solder thru for repairs, so yes, their thermal protection is low by design. I would think it would be enough unless you get stubborn with misapplication of your soldering iron
Les_Garten Posted November 5, 2009 Author Report Posted November 5, 2009 Can you send the PCB back as defective? Conformal coatings are usually solder thru for repairs, so yes, their thermal protection is low by design. I would think it would be enough unless you get stubborn with misapplication of your soldering iron I don't think it needs to be sent back if I can seal it. On the KGSS boards, what is the arc potential at the outputs? It would have to jump 1.40 mm from the R- output Pad. I thought it was about 3mm but it's closer than that. I mic'd it at 1.40mm.
Pars Posted November 5, 2009 Report Posted November 5, 2009 I think it is MG chemicals that makes Q-dope or Corona dope, both of which are HV insulators. Might be another option.
Les_Garten Posted November 5, 2009 Author Report Posted November 5, 2009 I think it is MG chemicals that makes Q-dope or Corona dope, both of which are HV insulators. Might be another option. Hey Pars, Thanx! The Q-Dope it looks like was DC'd. I did find the Corona dope and it looks like it should work! It's only $11:00 a bottle. I just got a call back on this Loktite product: Hysol 0151 is is supposed to be able to go through a solder wave process and act as a solder mask. http://tds.loctite.com/tds5/docs/HYSA0151-EN.PDF
Les_Garten Posted November 6, 2009 Author Report Posted November 6, 2009 Can you post a picture? Just for you! Click It!
nattonrice Posted November 7, 2009 Report Posted November 7, 2009 If you're putting a terminal block on top of that just give it a lick of nail polish.
justin Posted November 7, 2009 Report Posted November 7, 2009 i thought i was picky if you're ever relying on soldermask on an electrostatic amp pcb to prevent a short you're already in trouble
nattonrice Posted November 7, 2009 Report Posted November 7, 2009 In the theme of the above two and just incase you missed Spritzer's warning.~ Remember don't mount the heat-sinks flush to the board.
Les_Garten Posted November 7, 2009 Author Report Posted November 7, 2009 If you're putting a terminal block on top of that just give it a lick of nail polish. Was going to solder, not use terminal blocks.
Les_Garten Posted November 7, 2009 Author Report Posted November 7, 2009 i thought i was picky if you're ever relying on soldermask on an electrostatic amp pcb to prevent a short you're already in trouble I'm just trying to fix the void on the board. I'll be soldering to that pad next to it. The hole in the solder mask is 1.4mm from the edge of the pad. How much potential exists between that output and the ground plane? I thinkl I'm going to use the Locktite product. Ohh, and you guys didn't start out "all seeing and all knowing". I've read your old posts!
justin Posted November 7, 2009 Report Posted November 7, 2009 I'm not sure why it matters. It's not going to arc because a small section of soldermask is missing. And that distance would have to be like 100x smaller to see arcing assuming there were no contaminants on the board
peranders Posted November 9, 2009 Report Posted November 9, 2009 Just for you! Click It! I would worry a thing about this if we talk in electrical terms. BTW: The copper seems thick.
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