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PCB photoresist method fail

MacIntoshCZ

Member
Hello everyone,
I am failing to get decent quality pcb. Biggest problem is that foil is not removed correctly. As you can see in image there are spots where you can see cuprexit layer, but honestly that was done by my finger. I am using negative photoresist film. Its old one and its really blue even before UV light exposure. I dont know what can cause this. Any ideas? IMG_20200813_113156.jpgIMG_20200813_113442.jpg
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Hello everyone,
I am failing to get decent quality pcb. Biggest problem is that foil is not removed correctly. As you can see in image there are spots where you can see cuprexit layer, but honestly that was done by my finger. I am using negative photoresist film. Its old one and its really blue even before UV light exposure. I dont know what can cause this. Any ideas?
Presumably, and fairly obviously, it's long out of date?.
 

gophert

Well-Known Member
Most Helpful Member
This last photo looks like it worked perfectly - you just need to put it back in ferric chloride etch solution for another few minutes. It will look great after that.
 

MacIntoshCZ

Member
This last photo looks like it worked perfectly - you just need to put it back in ferric chloride etch solution for another few minutes. It will look great after that.
It tooks around 30mins to etch in hcl + peroxide.
 
Last edited:

Pommie

Well-Known Member
Most Helpful Member
I use Amonium persulphate for etching but gave up making my own about 8 years ago. When I did make them I found that edge burrs can stop things working properly.

Mike.
 

gophert

Well-Known Member
Most Helpful Member
It tooks around 30mins to etch in hcl + peroxide.
That's pretty typical for 1oz copper if you are not agitating it. It tends to go faster if you put the board copper-side down and slowly move the dish. Also, if the copper stops dissolving, it means you've run out of active peroxide in your mix. Peroxide is an unstable material and is constantly decomposing - even in the bottle. So, you can assume the concentration is lower than the label says.
 

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