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Subject: Re: [Homebrew_PCBs] Question about dry film negative photoresist...

From: James <bitsyboffin@...>
Date: 2013-09-05

The points I gave still apply, they are the reasons for easy to remove resist. 

Although I wonder if you may be doing something a bit weird, no need to "let the board dry overnight", if you're leaving it wet with developer, that would be a problem ("developer" works as a stripper too, given time), rinse with water and dry it off with a paper towel as soon as you have developed it.

To give you an idea...

Clean blank PCB: 3 minutes
Attach film: 5 minutes
Dark Rest: until cooled (5-10 minutes)
Setup for exposure: 3 - 5 minutes
Expose: 2.5 minutes
Dark Rest: 3 - 5 minutes (if you bother, I don't)
Develop: 2 - 5 minutes in 20g/L warm Sodium Carbonate solution
Etch: depends on etchant
Strip: 10 minutes - 30 minutes in hot strong Sodium Carbonate solution

from a dirty blank PCB, to an etched board ready to drill, it takes about an hour including messing around with artwork etc...




On 05/09/13 13:30, twgray2007@... wrote:
 

No, after developing and letting the board dry...usually overnight...the resist just flakes off in some spots.