neighbor@csd4.milw.wisc.edu (Jeffrey Alan Ding) (07/02/87)
References: Hello. Does anybody out there etch PC boards? I have a kit from GC electronics that uses chemicals to transfer a pattern onto the PC board. The artwork for the pattern is done on transparent plasic. The artwork is placed onto a PC board which is photo sensitized and exposed to Ultra Violet light. Then the PC board is developed and the pattern appears on the PC board. This method is very useful if multiple PC boards are wanted having the same circuit design. I'm wondering if anybody out there has used this stuff. I'm having a bit of trouble photo sensitizing my own PC boards. I've tried the process with PRE-sensitized boards and it works great. But the boards that I sensitize do not work at all. If any of you have any experience doing this I would appreciate any info on how to make it work. Oh one more thing, I'm using POSITIVE method. There are both positive and negative methods. Thanks in advance...... Neighbor
neighbor@csd4.milw.wisc.edu (Jeffrey Alan Ding) (07/02/87)
Opps.......wrong newsgroup. sorry something went screwy!!! I was on sci.electronics Neighbor
jeffr@sri-spam.istc.sri.com (Jeff Rininger) (07/02/87)
In article <2392@uwmcsd1.UUCP> neighbor@csd4.milw.wisc.edu.UUCP (Jeffrey Alan Ding) writes: > [. . .] >I'm wondering if anybody out there has used this stuff. I'm having a bit >of trouble photo sensitizing my own PC boards. I've tried the process >with PRE-sensitized boards and it works great. But the boards that I >sensitize do not work at all. [. . .] I've had problems with sensitizing my own boards; the problems were caused by spraying the photo-resist on the board too thick. For one-offs, why not use Stahler mills (which I've hyped on this newsgroup before) and spare yourself all the etching hassle ?
jpexg@mit-hermes.AI.MIT.EDU (John Purbrick) (07/05/87)
Re how to make usable PC boards: Cleanliness is next to godliness!! Put on rubber gloves. Take the board to a sink (not a heat sink, dolt!) and scrub it with Ajax or a similar abrasive cleaner. Get it so that the board has a little "tooth", that is, a uniformly rough surface. It has to be so clean that water won't bead up on it. Then shake off as much water if you can--blasting it with compressed air is better, the idea being to stop the impurities in the water from drying on the surface. Let the board dry in a dust-free location, resting on an edge, not flat. From now on I can only speak of negative resist, but yours should be similar. Handling the board by its edges, pour a uniform coating of resist over it. Tip it back and forth, and let as much of the resist drip off as you can, the idea now being to get a very thin coating. It helps to warm the board (with a heat gun if you have one) as this makes the resist flow better, but use some caution as the resist may well be flammable. Again, dry on edge away from dust. After 24 hours you should be able to use the board. Make sure that your artwork is clamped firmly to its surface. We used a setup of glass sheets on both sides of the board, clamping it with bulldog paper clips--the artwork must be flat! Then expose, develop and etch. The last stages are the easiest.
ornitz@kodak.UUCP (barry ornitz) (07/08/87)
In article <2392@uwmcsd1.UUCP> neighbor@csd4.milw.wisc.edu.UUCP (Jeffrey Alan Ding) writes: > >Hello. Does anybody out there etch PC boards? I have a kit from >GC electronics that uses chemicals to transfer a pattern onto the PC board. >The artwork for the pattern is done on transparent plasic. The artwork is >placed onto a PC board which is photo sensitized and exposed to Ultra Violet >light. Then the PC board is developed and the pattern appears on the >PC board. This method is very useful if multiple PC boards are wanted having >the same circuit design. > >I'm wondering if anybody out there has used this stuff. I'm having a bit >of trouble photo sensitizing my own PC boards. I've tried the process >with PRE-sensitized boards and it works great. But the boards that I >sensitize do not work at all. If any of you have any experience doing >this I would appreciate any info on how to make it work. Oh one more thing, >I'm using POSITIVE method. There are both positive and negative methods. Jeff, I sensitize my own boards most of the time with consistently good results using Kodak KPR resist which unfortunately Kodak recently sold the rights to another company. Resist of this type has a definite shelf life and is quite sensitive about how it is stored. I have rarely had any luck using the spray- on resists sold by GC, etc. This products rarely sells quickly and is useless if overheated in the can. You might consider the Photo-Blue or Photo-Green (tm ?) presensitized boards which develop in a non-solvent developer which is much safer to use. If you really want the high definition needed for complex PC boards, you will probably have to go with the KPR type resists. Now for a plug - especially since Kodak sold off their interests. Buy the book, "Electronic Prototype Construction" by Stephen D. Kasten. This book is published by Howard W. Sams (ISBN 0-672-21895-X) and can be ordered through most major electronic distributors. The cost is about $18 and your money will be very well spent. Steve presents some of the most practical information I have seen on the subject. The book is well suited to beginners as well as more experienced users. The book is full of photographs and illustrations and is a storehouse of useful tips. Even if you value your time at next to nothing, this book will save you money. All hams and electronic experimenters should have a copy. If this sounds like a blatant ad, it is. Steve is a coworker and close personal friend. I feel as if I have created a monster because I was the one to introduce Steve to hamfests as a source of electronic goodies and junque. It seems that on every occasion, he is working on a new project with parts he bought at a hamfest. Buy his book - he needs the royalties to buy more parts and supplies. Seriously, his book is every bit as good as I said it was! Barry ----------------- | ___ ________ | | | / / | | Dr. Barry L. Ornitz UUCP:...!rochester!kodak!ornitz | | / / | | Eastman Kodak Company | |< < K O D A K| | Eastman Chemicals Division Research Laboratories | | \ \ | | P. O. Box 1972 | |__\ \________| | Kingsport, TN 37662 615/229-4904 | | -----------------
hoffman@pitt.UUCP (Bob Hoffman) (07/08/87)
In article <885@kodak.UUCP> ornitz@kodak.UUCP (barry ornitz) writes: >In article <2392@uwmcsd1.UUCP> neighbor@csd4.milw.wisc.edu.UUCP (Jeffrey Alan Ding) writes: >> >>Hello. Does anybody out there etch PC boards? I have a kit from >>GC electronics that uses chemicals to transfer a pattern onto the PC board. ... >>I'm wondering if anybody out there has used this stuff. I'm having a bit >>of trouble photo sensitizing my own PC boards. I've tried the process >>with PRE-sensitized boards and it works great. But the boards that I >>sensitize do not work at all. If any of you have any experience doing >>this I would appreciate any info on how to make it work. Oh one more thing, >>I'm using POSITIVE method. There are both positive and negative methods. ... >I have rarely had any luck using the spray- >on resists sold by GC, etc. This products rarely sells quickly and is useless >if overheated in the can. I have used the GC negative-acting photoresist with excellent results, but I had a fresh can. I guess I was lucky! What Barry says is true about its aging properties. I have learned that if the spray comes out a dark purple color, then it's OK. If it comes out yellowish, it's shot. Another important thing is extreme cleanliness of the board being sensitized -- this means taking scouring powder to clean any oxidation and oil off the board. Use 600-grit wet emery paper or steel wool if necessary. I don't like steel wool for the bits of steel it leaves behind. That board should positively GLEAM when you're done. Then, handle it only by the edges -- the oil on your fingers is enough to screw up the photoresist. -- Bob Hoffman, N3CVL {allegra, bellcore, cadre, idis, psuvax1}!pitt!hoffman Pitt Computer Science hoffman%pitt@relay.cs.net
deann@auscso.UUCP (DeAnn Kiser) (07/10/87)
Just a note to say "Hi" from a fellow Kodaker down in Austin, Texas.
Les G. Kiser
Field Service Rep.
(Ektaprint)dale@amc-vlsi.UUCP ( AMC Staff) (07/10/87)
In article <5775@pitt.UUCP>, hoffman@pitt.UUCP (Bob Hoffman) writes: > thing is extreme cleanliness of the board being sensitized -- this means taking > scouring powder to clean any oxidation and oil off the board. Use 600-grit > wet emery paper or steel wool if necessary. I don't like steel wool for the > bits of steel it leaves behind. That board should positively GLEAM when you're > done. Then, handle it only by the edges -- the oil on your fingers is enough > to screw up the photoresist. In my most recent employment I was involved in P.W.B. prototype fabrication both single and double sided. The problems with steel wool pieces are solved using 600-grit emery paper, however this is still too abrasive and you remove more cladding than you should. The best cleaning method that we developed is as follows: - Cut appropiate size board, and debur edges. -Hot water, Comet (household cleanser), and Scotch-Brite. The hot water and comet remove the oxidization with the aid of the synthetic material scotch-brite. I don't know the commercial usage of the stuff but it will rip your skin off if you miss the pwb as your doing your work. The scotch-brite has added advantages, its cheap doesn't leave any residue etc. - Rinse board in clean hot water, towel dry and immediately rinse with isopropal and allow to air dry on edge. We found that the board would positively "GLEAM" after these steps were taken. Also process your cards as soon as you can as oxidization has no concience. If you can't, leave them in a isopropal bath until your ready. Try it! Dale K. Wlasitz
lars@sdcsvax.UCSD.EDU (Lars Poulsen) (07/25/87)
In article <371@amc-vlsi.UUCP> dale@amc-vlsi.UUCP ( AMC Staff) writes: > ... the synthetic material scotch-brite. I don't > know the commercial usage of the stuff but it will rip > your skin off if you miss the pwb as your doing your > work. The scotch-brite has added advantages, its cheap ... The manufacturer's intended use of Scotch-Brite is to clean sinks, pots and pans. Yes, it is often used in conjunction with "the commercial cleaner Comet". Available in every Grocery store .... Cheers for reality. / Lars Poulsen