--- In
Homebrew_PCBs@yahoogroups.com, "jberghout" <jberghout@...> wrote:
>
> Hi. I'm new to the group. I was recently bitten by homebrew PCB bug. But I've been scratching my head, wondering why it so hard to find the solder resist film in the US. I realize that a solder resist is no necessarily necessary for DIY boards that don't use surface mount components. But it's something that I would still like to use to make my boards look more professionally, and to protect it from the environment.
>
> The ink they sell from china on ebay is primarily used for silk screening. and I might end up going this route, but it sure would be nice to have film available for one off designs.
>
> Is there just not enough demand? Are there any other reasons?
>
> Thanks in advance...
>
I have some DuPont Dry Film Soldermask if there is any interest. It takes quite a bit of pressure to laminate this film and you would also need a very powerful UV lamp to expose it. I used a DuPont vacuum laminator and a 5 kW exposure unit to process this material. It develops in a 1% sodium carbonate aqueous solution, same as the dry film used for primary circuit imaging although the development cycle is longer.
The newer liquid photo imaged soldermask materials are probably better to use in a hobby setting. You can apply these liquid materials with a blank silk screen, bake until "tack free", expose, develop and final thermal cure. Not a lot of expensive equipment is needed unlike the dry film soldermask.
The only advantage I can think of when using dry film soldermask is that it will readily tent over almost any size hole. One job I did years ago with dry film soldermask required tenting over 0.250" holes and this film worked with almost zero rejects. Other than for tenting applications I wouldn't use this stuff now days.