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nisios
Joined: Sep 02, 2006
Posts: 49
Location: Lisboa - Portugal
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 Posted: Mon Nov 27, 2006 2:32 pm Post subject:
PCB protection |
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Hi everyone.
What is the best method to protect pcbs from oxidation?
I think your answers will be spray coating but that raises another question......do i spray it before or after soldering? is it possible to solder throu the coating? And what about brands?
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State Machine
Janitor
Joined: Apr 17, 2006
Posts: 2810
Location: New York
Audio files: 24
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| Posted: Wed Nov 29, 2006 10:32 am Post subject:
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| Quote: | | I think your answers will be spray coating but that raises another question......do i spray it before or after soldering? is it possible to solder throu the coating? And what about brands? |
Normally you really don't need to conformal coat a board unless you are in a VERY high humidity environment. Otherwise, your boards will last years without coating, especially if they incorporate solder mask.
If you DO conformal coat the boards, with spray or brush on type, you generally do it after you solder all you components. First, clean the board with degreasing agent or denatured alcohol. If there are IC's that are socketed, then pull the IC's from their sockets. If you have any connectors, then mask them. You don't want coating in those areas. Mask the sockets with masking tape also. Spray your coating, let dry throughally then reinstall the socketed IC's.
Bill |
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nisios
Joined: Sep 02, 2006
Posts: 49
Location: Lisboa - Portugal
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| Posted: Wed Nov 29, 2006 12:24 pm Post subject:
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Thanks for the tips.
I dont know, but i made a couple of boards and after 2 weeks they were clearly oxidating.....nothing very serious but in a couple of years there would be a problem. Now imagine i do as you told and a a component needs to be replaced. Is there any problem....unsoldering with coating?
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jksuperstar
Joined: Aug 20, 2004
Posts: 2503
Location: Denver
Audio files: 1
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| Posted: Wed Nov 29, 2006 12:39 pm Post subject:
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| If you are using thru-hole parts, you shouldn't have any problem at all. Some very small surface mount devices may give you a bad solder joint if replaced, but you should'nt have a problem if you can flux & re-tin those areas before dropping in a new part. |
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toppobrillo
Joined: Dec 10, 2005
Posts: 766
Location: oakland, ca
G2 patch files: 1
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| Posted: Wed Nov 29, 2006 2:18 pm Post subject:
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you can tin plate the boards which is easy and works well. another alternative is to wick solder over all the traces, easy to do a light coating..
also you can use clear spray lacquer. |
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State Machine
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Joined: Apr 17, 2006
Posts: 2810
Location: New York
Audio files: 24
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| Posted: Thu Nov 30, 2006 7:28 am Post subject:
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| Quote: | | Is there any problem....unsoldering with coating? |
No, not a big problem BUT I personally strip the coating off the bad part with using alcohol first, then remove and replace the defective part, then touch up the coating with a small brush. If you replace the part with coating on the pads, it gets messy. You want a CLEAN solder joint.
ALSO, ONE THING ABOUT COATING, YOU HAVE TO BAKE THE BOARD TO COMPLETELY DRY THE CIRCUIT CARD OR ELSE YOU WILL JUST TRAP MOISTURE IN THE BOARD WITH THE COATING ....
SO, CLEAN, BAKE DRY THEN COAT THE BOARD ....
I hope these tip help you ....
I am curious though, how or where were these boards that had the oxidation build up so quickly?
Bill |
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