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.
randys@mipon3.intel.com (Randy Steck) (07/10/87)
In article <2868@mit-hermes.AI.MIT.EDU> jpexg@mit-hermes.AI.MIT.EDU (John Purbrick) writes: >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. Another method that gives very good results is to mount the board on a rotating platform while pouring/spraying the resist on. This gives a thin coating of resist, depending on the viscosity of the resist and how fast you are spinning it. An electric drill with variable speed works well here. -- Randy Steck Intel Corp. ...intelca!mipos3!omepd!mipon3!randys
gwyn@brl-smoke.ARPA (Doug Gwyn ) (07/13/87)
I just recalled that someone had suggested drying a cleaned board with compressed air. Be advised that some (maybe most) sources of compressed air add a non-negligible amount of oil to the air.