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Re: Photo postive method

7/9/2000 10:52 PM
Re: Photo postive method
"Not so...P-N-P... is easy to goof unless pressure, heat and time are exactly right when you iron it on, not to mention that the pcb material must be absolutely sparkling clean...  
The P-n-P lines tend to spread with too much pressure or heat, and too little will keep it from sticking. "
True - but several hundred beginners of all stripes have made and been quite happy with PNP from GEO's toner transfer packages, by following the directions. Yes, some care is needed, but it's fairly forgiving. At the worst, you wipe off the messed up transfer and try again. Yeah, resolution is limited, as I said; but most beginners don't need or want the resolution, as I said. And NO PCB etching should be done with less-than-sparkling-clean stock. The advantage with pre-coated stuff is that the cleaning is part of what you bought.  
And, to paraphrase a wise man I once knew; to each his own, and good results can be had with both, but beginners should not be put off from trying PNP methods. A good laser print on blue PNP with reasonable attention to the instructions often gives a quality first-time PCB, and no equipment needed other than an iron and an etch pan.  
But back to the photo stuff. You get OK results with Evermuse even with lighter stripes and less dense pinholes in the black on your transparencies? Maybe I'm exposing too long. I made an exposer with two unfiltered blacklight tubes and a vacuum frame (sheet of glass on a piece of plywood with masking tape around the edge and a vacuum pump hauling the air out). Seems to work great with real photo stuff but not for inkjet.  
Good trick with the minimal-developer stuff.
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