Fixing pin-holes on lasered PCB transparencies

[Pat Pending]

http://www.caseyspm.com/cgi-bin/casey/Fixative

FYI - Some of you might find this useful.

Caseys' Ultra Black uses solvents to reflow the toner.

[robrenz]

I would try regular clear lacquer from the hardware store at $3.00 to $4.00 per can instead of $13.00.  I would bet that the ultra black is just that, especially since they say it smells like lacquer thinner.

[nukie]

Rob I do believe in what you said and I will definitely try it the next time I make a PCB. But I keep wondering, how does aerosol dissolve the plastic toner and does it change the width of my tracks? I am doing DFN packages mostly nowadays.

[robrenz]

IMO the amount of volatile solvent left in the lacquer droplets when they hit the page is just enough to disolve the toner particles to the point they melt in to each other.  If you spray a thick layer on all at once so the toner can swim for a while you probably will get a mess.  As with most fixative type spraying situations a light even coat is probably best and if you want heavier coverage do it in multiple light coats.

[nukie]

During the ironing/laminating process, does the clear lacquer get transferred as well? If the clear lacquer gets transferred, then wouldnt the exposed areas to be etched get masked by the lacquer?

I use pulsarfx transfer papers, expensive but it is a very predictable and excellent consistency compared to magazine papers and etc. It saves me a lot of time. My problem is my Canon printer, its fine printing text, the quality is great but not when printing large area it will be uneven and it pits. The settings are at darkest toner output.

I have access to a huge Canon laser copier??? at one of my work place the printout is amazingly thick and black. But most prototyping is done in my cottage.

I don't think I want to invest in another printer since the old one is still working fine. So any kind of toner darkening agent is real helpful for me. Pulsarfx greentrf doesn't work for me, it doesn't work well for very fine tracks.

[robrenz]

I think you are right. In a toner transfer situation (which I was not even considering in my previous comments  ) the lacquer would probably bond everywhere making it useless for etching.  In re-reading the OP product info it is sold as a fixative only, it is not some magic stuff for toner transfer method.  I only chimed in because I was pretty sure the stuff was just lacquer, not because I have any great knowledge of toner transfer method.

[nctnico]

I print my layouts on tracing paper (60gr/m2 Glama basic from Schoellershammer) for use with UV sensitive PCBs. Works excellent even when the layout does not appear fully black. There is enough toner to block the UV.

[nukie]

Regardless, I am still going to try it for once to witness myself. I will report back when I have results.