Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

storan4wd wrote:

> --- In Homebrew_PCBs@yahoogroups.com, Kerry Wentworth <kwentworth@...> wrote:
>
>> storan4wd wrote:
>>
>>> I've been playing with some UV curable green solder mask (Mechanic Brand from China eBay - comes in a 10ml syringe for £1-2).
>>>
>>> I get a really even coating by applying it through a silk screen mesh.
>>>
>>> You're supposed to lay the artwork over the top and expose it. Then wash away the non-cured parts with solvent. This doesn't work because it is impossible to lay the artwork over the mask without getting bubbles / large voids; if you try lifting the artwork to try again it instantly wrecks the nice even layer. To add insult to injury, if you do get it right then the mask sticks to the artwork like cement after curing.
>>>
>>> I tried an intermediate layer of florists cellophane over the mask; this again is virtually impossible to apply without bubbles but it separates easily after curing.
>>>
>>> I'd give up because it takes such a lot of faffing except for the fact that when I get a large bubble free area the mask looks really good and it's possible to incorporate legend with the track mask which can be scrubbed over with a chinagraph pencil to look like a real silk screen.
>>>
>>> Any thoughts/techniques please?
>>>
>>> Bob
>>>
>>>
>> As long as you are applying it with a silkscreen, why not block out the
>> parts where you don't want masking?
>>
>> Kerry
>>
>>
> Hi Kerry,
> I use a silk screen mesh but there's no image on it - it's only to ensure and even coating.
> Bob
>

But you COULD put an image on it, and have the soldermask only placed
where you want it. Then just expose the whole board. Wouldn't that be
easier?

Kerry