PCB photoresist method fail

[MacIntoshCZ]

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?

 

[MacIntoshCZ]

 

[MacIntoshCZ]

I cant develop it longer. Traces will be destroyed.

 

[Nigel Goodwin]

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Presumably, and fairly obviously, it's long out of date?.

 

[MacIntoshCZ]

Presumably, and fairly obviously, it's long out of date?.

Honestly i dont know. Bought like 3 years ago from china. When it cames it already has dark blue color.

 

[MacIntoshCZ]

 

[gophert]

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]

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.

 

[Pommie]

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]

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.