David

If you have to conformally coat, then you have certain needs of
reliability. I honestly don't think that any wax I know of could be
guaranteed to offer this, especially on one side. If the wax is soft at
operating temp, its protection will be minimal. If it hard, it will chip
off with your test probes, as adhesion will be poor.

I believe there are in-line coaters available and a low-cost PU or PMMA
coating will do the job properly (consult Graham Naisbitt for advice).
You can automatically spot-mask your test points, too.

Brian

David Hannick wrote:
>
> hi.
>
> Has anyone experienced or heard of using wax as a type of cheap conformal
> coating. Our company is looking at conformal coatings at the moment but
> equipment costs are high, our product has low margins and our manufacturing
> process would have to change from a cell / line (one piece flow) set up to a
> batch setup.
> We were thinking that we may just have to coat one side of the boards only
> and so wax could be applied using wave soldering type equipment.
> Our main problem with using regular conformal coatings is that our final
> functional tests are carried out via test pads while the PCBs are in their
> plastic enclosures. Wax would allow us to continue doing this as the test
> pins could pierce through the wax to contact the test pads and afterwards
> these pin holes would be minimal as wax has a small degree of reflow /
> creep. Otherwise we would have to selectivily spray the conformal coatings,
> missing the test pads but leaving them more vunerable to damage / corrosion
> while is service.
> Has anyone any experience of wax coating PCBs.
>
> Best regards
>
> David Hannick
>
> Ei Electronics
> Shannon
> Ireland.
>
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