Advice please making PCBs using Press n Peel film

[ljcox]

I have successively used Press n peel to make at least 2 double sided PCBs several years ago.
But over the last few days, I have been trying without success to do another PCB & don't know why it is not working.

I followed the Press n Peel instructions.
i.e. I rubbed the bare copper with steel wool, then washed it with soap & water, then washed the soap off and dried it with a lint free cloth.
But after much ironing, only a few slight traces of tracks were visible.

I also used a procedure I found on an electronics forum which is essentially the same but it uses isopropyl alcohol rather than soap & water. The result was slightly better, but certainly not adequate.

I really don't know why it worked previously but not this time. I used the same HP Laser printer.

I also heard that the PCBs can be made by simply printing the image of paper rather than the P n P film. But apparently it takes a lot of work to remove the paper. However, if it works, I will do it that way.

Any assistance will be appreciated.

 

[betwixt]

I have tried test boards using that method and never got anything good from it. If you invest in a UV exposure box and some chemicals you will get professional results every time and the artwork can be reused over and over again.

Brian.

 

[ljcox]

Thanks Brian.
How do you clean the copper before exposing it to the UV? Or do you buy a PCB with a photosensitive coating?
Len

 

[betwixt]

I normally buy prepared boards with the resist paint already on them. On a few occasions the production has been aborted due to last minute design changes after the board has been exposed. When that happens I clean the board with 'Ultrasolv' (from Electrolube) to take it back to clean copper then spray it with a new layer of resist paint to start over again. Its messy but it saves a PCB that would otherwise be scrapped.

Brian.

 

[ljcox]

Thanks Brian. I live in Australia so I don't know if we have that product here. I'll do a search.
I think my problem with using Press n Peel is due to me not cleaning the copper properly.
As I wrote in the initial post, I followed the Press n Peel instructions, i.e. used steel wool, then washed it with soap & water, then washed the soap off and dried it with a lint free cloth.

Then I tried isopropyl alcohol rather than soap & water.

Would Ultrasolv do the job with or without the steel wool?

Len

 

[betwixt]

I doubt the problem is the cleanliness of the PCB, more likely the film has 'dried out' (aged) and lost some adhesion or the temperature is wrong.

You can get ULS here: https://au.element14.com/search?st=uls It is expensive but I find a 1L bottle lasts at least a year.

Brian.

 

[RushPCBUSA]

Try using scotchbrite (eg. nylon pan scourer) rather than steel wool - that may be roughening the surface of the copper too much?
Also try kitchen towel for drying, in case the cloth has some residue such as fabric conditioner.

Be careful not to touch the copper surface at all after cleaning it, just a fingerprint can make a mess of a degreased surface.