Hi all,
a while ago I had a batch of PCBs produced by Gold Phoenix and they looked really great. But when I now look at them, they look tarnished (hope this is the right word). Some of the soldering pads changed the color.
A couple of boards produced by BatchPCB are still looking like the first day.
Could it come from ROHS-free finishing? I selected OSP, which was the cheapest? Should I use silver for the next batch?
Cheers,
Alex
Silver will tarnish, of course, but it shouldn’t have any effect on solderability. Gold is best, but costs more. Assembly companies prefer it.
Perhaps they had a problem with their OSP finishing. It’s a good idea to use boards fairly soon after they have been made, they absorb moisture which can affect soldering.
Leon
Hi Leon,
thanks for your answer. Scanning through my email conversation again, I think it’s actually silver.
This is is from the quote they send me:
FR4 1oz Immersion silver 1.7"X0.9"
Cheers,
Alex
9600baud:
Hi all,a while ago I had a batch of PCBs produced by Gold Phoenix and they looked really great. But when I now look at them, they look tarnished (hope this is the right word). Some of the soldering pads changed the color.
Most of my GP boards still look brand new after sitting on the shelf, but this has happend to me a couple of times. I found some good isopropyl alcohol and a lint free pad cleaned the pads right up.
Googling a bit I found this post, maybe it’s helpful to others too:
http://www.robotroom.com/PCBTarnishEraser.html
He uses a rubber eraser for detarnishing his PCBs. Very detailed and in depth information on the process and the result.
A little bathroom cleanser (like Comit), gently applied, will clean your boards right up, and then a little wax will protect them from further corrosion. Aesthetics aside though, copper oxide is a good conductor and hasn’t effected the functionality of my home-made, un-plated boards.
I’ve used spray acrylic on a few boards after assembly to good effect, although the approach makes boards very hard to repair.
curtcarpenter:
copper oxide is a good conductor and hasn’t effected the functionality of my home-made, un-plated boards.I’ve used spray acrylic on a few boards after assembly to good effect, although the approach makes boards very hard to repair.
My understanding is that most off-the-shelf electronics devices have a thin, rubbery, transparent film of conformal coating sprayed or dipped on after all the components have been soldered on.
I’m not sure what exactly the stuff is, but it vaporizes pretty quickly when I touch it with a soldering iron – it’s no harder to repair than a board without the stuff.
It is polyurethane. But if once sprayed, tough to remove for servicing.DavidCary:
curtcarpenter:
copper oxide is a good conductor and hasn’t effected the functionality of my home-made, un-plated boards.I’ve used spray acrylic on a few boards after assembly to good effect, although the approach makes boards very hard to repair.
My understanding is that most off-the-shelf electronics devices have a thin, rubbery, transparent film of conformal coating sprayed or dipped on after all the components have been soldered on.
I’m not sure what exactly the stuff is, but it vaporizes pretty quickly when I touch it with a soldering iron – it’s no harder to repair than a board without the stuff.
I think the coatings are hard on soldering tips too. No proof, just general impression. Especially the really thick coatings on old boards.
I've replaced components on conformal coated boards.mvs sarma:
It is polyurethane. But if once sprayed, tough to remove for servicing.DavidCary:
My understanding is that most off-the-shelf electronics devices have a thin, rubbery, transparent film of conformal coating sprayed or dipped on after all the components have been soldered on.I’m not sure what exactly the stuff is, but it vaporizes pretty quickly when I touch it with a soldering iron – it’s no harder to repair than a board without the stuff.
Using my soldering iron to vaporize the coating – at the perimeter of the component I’m trying to take off – seemed pretty easy.