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| Dry film photoresist developing |
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| sleemanj:
Still overexposed in your second attempt. Don't overestimate how exposed you need it, you really only need it "just visible" when you develop it. You probably only need like 40 seconds, perhaps a minute going by your images (of course sunlight exposure is rather imprecise, but there's plenty of margin). See page 13 of my tips https://sparks.gogo.co.nz/dry-film-tips.pdf Look how the exposed areas are only a little darker. In short, expose just-long-enough to develop cleanly, it will be a bit soft and fragile but hard enough to withstand light rubbing or vibration from an electric toothbrush (gently, not scrubbing!), after developing put it in the sun for a few minutes and the resist will get much darker and harder to withstand the etching and handling better. |
| Jwillis:
One thing I forgot to mention is the laminating temperature.Don't get to high or that can caused premature polymerization of the film.This can cause difficulty at the development stage. This happened to me when I got started and had similar problems. I had also received film that looked darker than normal and didn't work very well. Wonder if X-rays may have been the problem passing customs.Noway of really knowing. |
| rcbuck:
When you laminate the dry film to the copper clad board are you working in a yellow light environment? That is recommended, or at least a very dimly lit room. Taping the tracing paper to the board material will not create a close enough contact with the dry film. You need to use a piece of glass as JackJones suggested to hold the tracing paper against the board. Also, tracing paper is not the best material to use for your negative. Clear mylar laser jet film is best. I mirror the image when I print mine so I can press the printed side of the mylar against the board. This ensures the tightest fit. |
| ZeroResistance:
--- Quote from: rcbuck on April 01, 2019, 06:41:34 am ---When you laminate the dry film to the copper clad board are you working in a yellow light environment? That is recommended, or at least a very dimly lit room. Taping the tracing paper to the board material will not create a close enough contact with the dry film. You need to use a piece of glass as JackJones suggested to hold the tracing paper against the board. Also, tracing paper is not the best material to use for your negative. Clear mylar laser jet film is best. I mirror the image when I print mine so I can press the printed side of the mylar against the board. This ensures the tightest fit. --- End quote --- While working on the film I tried to keep light at a minimum. But not yellow light. By yellow light would you mean a low wattage incandescent bulb? I had to go for tracing paper because the transparencies that I had were not laser compatible and there were lot of holes in it. So I printed on tracing paper because the toner tends to bind better on these. |
| beanflying:
--- Quote from: ZeroResistance on April 02, 2019, 05:43:39 am --- While working on the film I tried to keep light at a minimum. But not yellow light. By yellow light would you mean a low wattage incandescent bulb? I had to go for tracing paper because the transparencies that I had were not laser compatible and there were lot of holes in it. So I printed on tracing paper because the toner tends to bind better on these. --- End quote --- It is getting fairly difficult to get hold of Photographic Incandescent bulbs so I roilled my own LED one. https://www.eevblog.com/forum/projects/homemade-pcb-exposure-units/msg1477465/#msg1477465 Also that thread is my Scanner hack for an Exposure unit. Works well and reminded I should go add a few more posts to it sometime :palm: |
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