> But I said several days before that is possible to apply the photoresist by using blank screen mesh and I though was better using the RC reference. Am I right ?.
>
> By the way...
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> How do you do to match the trasnparencies for expossing a double sided PCB.. do you have any web site where It is explained using pictures or something ?
>
>
> Thanks for your help
>
> Sincerely
>
> Ingeniero Andres F. Hernandez
> Pontificia Universidad Javeriana
We were talking about solder mask and legend ink for the blank screen mesh. However, someone sended me an email just a few days ago to tell me that AQ3000 is available now and ready for sale in SP composition (screen printing). I did not verified that information, but in that case, yes, you can apply photoresist with a blank screen mesh (but better to read the product datasheet first). I still feel that DC has more consistent results and yields than screen printing for photoresist only (not for solder mask and legend ink).
To match transparencies in a double sided board is a big problem, since normally you are matching not two, but five transparencies (top overlay, top soldermask, top layer, bottom layer, bottom soldermask).
I am assuming that you are talking about real phototools (laser photoplotted film) and no laser-printing over paper. You can build some punch and die device trimmed with cnc-machining which punch the phototools where the pcb-guides are (an area of the pcb that is not used for artwork, just only for adjustment drilled holes). You can see the process in the Bungard site video sections. Look for "laser plotting or photoplotter" and the look for "punch device" or so.