Homebrew PCBs

when you say "burn it off with a laser'  what laser are you using?


maybe a cnc machine?


dave






On 9/19/2016 10:59 AM, 'Tony Smith' ajsmith1968@... 
[Homebrew_PCBs] wrote:
>
> You don\u2019t need high temp paint, I think anything will work.  I recall 
> reading a recommendation to use water-based polyurethane (clear top 
> coat) as it apparently burns off without leaving a residue.  I\u2019ll give 
> that a try one of these days.
>
> There\u2019s no problem repainting the board after etching and using that 
> as a solder mask, all depends in how enthusiastic you want to be.  
> You\u2019d need to prepare another image so the laser can clear the pads.
>
> One page (or maybe Youtube video) that I can\u2019t find did talk about 
> using the laser to drill the holes after etching.  The conclusion was 
> that it wasn\u2019t worth the effort as the holes were of poor quality.  
> Pretty sure that was in FR4.  And of course that\u2019s another image 
> you\u2019ll need to prepare.
>
> Surface mount means you don\u2019t need many holes anyway, but a solder 
> mask would still be handy.  You could burn the component layout into 
> it as well.
>
> Might need to try this one of these days.
>
> Tony
>
> *From:*Homebrew_PCBs@yahoogroups.com 
> [mailto:Homebrew_PCBs@yahoogroups.com]
> *Sent:* Tuesday, 20 September 2016 3:09 AM
> *To:* Homebrew_PCBs@yahoogroups.com
> *Subject:* [Homebrew_PCBs] Re: Cermark Laser marking for PCB resist?
>
>
>
> Hang on... I don't think everyone understand the idea here, which is 
> already working just fine for at least some members (who I would 
> REALLY love to see pictures from, BTW Tony).
>
> 1. Clean PCB blank and spray with high temp black / dark paint.
>
> 2. Laser at low power / high speed to burn away paint around traces 
> (isolation) or raster for removal of larger areas.
>
> 3. Etch.
>
> 4. Leave the paint / melt in place over the traces (as soldermask) and 
> Laser again at higher power, to burn away paint / melt from solder 
> pads. In fact... spray the etched board again with green paint (or 
> whatever color) and laser that clear off the pads.
>
> 5. If you etched out a hole in the center of each through hole pad, 
> and have a high enough power laser, you might be able to laser cut 
> your holes through the FR4.
>
> Now you have a nicely protected PCB. Don't tell me the paint can't 
> manage the solder heat because there are very high temp paints.
>
> This REALLY sounds to me like something worth trying.
>
>
>
>
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