I will second David's comments on the photo process. I too have been making boards, both 1 and 2 sided, since about 1980 using the photo process; and like David, I highly recommend it. You can -easily- achieve 6-8 mil traces/spaces; unlike the toner-transfer method where you must use the greatest care to achieve a -clean and solid- 10 mils, let alone anything finer than that. In fact, with some careful attention, you can achieve -2 mils- with a dryfilm/photo process; which you simply -cannot- do with toner transfer, no matter what. I used an old hot-roll laminator found surplus; a surplus box of Dupont Riston dry-film; and made my own exposure frame using "germicidal" UV flourescent tubes (about 6-8 of them, as I recall). These lamps WILL hurt your eyes; as they are entirely UNfiltered; unlike so-called "blacklight" tubes, which ARE still filtering out the shortest and strongest UV. Exposure times with 6-8 of these 18" long tubes is in the range of just 1-2 minutes. I used regular washing-soda for developer and regular sodium hydroxide for stripper. I would pre-laminate half a dozen 12" square sheets of board; and store them in a cool place. When I needed to make a board or two, I'd simple shear these pre-laminated sheets to size; and within 10 minutes I'd have a fully developed board, with razor-sharp and 100% complete traces EVERY time; ready to drop into the spray-etcher. Artwork was generally laser-print on transparency film; unless I was doing a chem-milling job or something, where I needed the ultimate resolution; in which case I'd have my Gerber files photoplotted for 7 bucks at the local plotting-service. Again, this method gives HIGH quality results EVERY time, with EASE. To me, this -consistent- quality was WELL worth the few hundred bucks in parts and surplus equipment to set it up. Richard -- ============================ Please do NOT add or "subscribe" my name to ANY lists/databases.
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Re: Photolithography
2006-02-21 by Richard
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