Stephan,
Thank you for the reply.
Yes, two types. LPI (Liquid Photo Imageable) and dry film.
LPI cannot "tent" (bridge) vias, which could mean you have solder
under a SOIC--in the via. It's strength is that being liquid,
it "fills" the entire "terrain" of the pcb very well.
Which is the downside of the dry film soldermask. Unless
sophisticated techniques are used to bring it into full contact with
the board, it can fail rather easily. It also may suffer during hot
oil reflow operations, and wrinkle or rupture.
Both of these SM's are photoimageable, and process much like etch
resist, with the added step of baking required for full soldermask
standards compliance.
As I said, we've got a couple of really decent ways to get the
artwork image onto the board. And a couple decent ways to THP. And
the toaster oven technique for part mounting works well, if care is
used in the process.
Screen printing is cheap and easy to setup for component id, and bd
legends...
But lack of decent techniques/materials for soldermask is what
separates our HB PCB's from the "real" ones, IMO...
Ballendo
--- In
Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:
> I have read about soldermask that is exposed and developed like
> resist. sorry do not remember urls or names.
> there was one german company making it also i think.
>
> ST