Hi, thanks for adding me to the group.
I've just done a quick trial etch, with fair results for my first attempt in years. A scan of this board is at https://www.sendspace.com/file/5yy3qw , or if that's broken I can repost it again or somewhere else.
I used a 600dpi inkjet transparency (ok I know not great), Mega UV exposure box for 2.5 mins after a 5min pre-heat, sodium metasilicate developer at 20'C for about 3 mins, rinsed, etched with fresh sodium peroxidisulfate at 50'C for about 8 mins, rinsed, then wiped clean with resist stripper.
The main problem I have is that there are fine vertical
streaks of copper remaining on the board, and some track pitting. I can
only think that I should have exposed the board for longer, as perhaps
there was some resist still remaining when I etched the board.
(The bottom of the TQFP footprint got accidentally rubbed
away while I was trying to check if any resist was still clinging, oops!)
I think that the streaking problem is from the resist clinging due to underexposure/underdevelopment, but tell me what you think.
I think that the streaking problem is from the resist clinging due to underexposure/underdevelopment, but tell me what you think.
In any case, please would you kindly take a look at the results and give me your opinions?
Many thanks,Matt.