MG Chemicals now uses a white protective cover on its positive-resist boards. It appears that Ever-Muse (Circuit Specialists) also has a white protective cover. Injectorall has no protective cover. They come in black bags. The dry film, negative resist from MG Chemicals has a transparent-blue protective film on it. I believe the actual product is made by DuPont. Your boards could be pre-laminated with a negative-resist. At this point, I think it is futile to try to make a PCB without knowing whether your resist is positive or negative acting. If you can take your board and cut it into smaller pieces, you can determine that basic fact by experiment. Make a very dense exposure mask with two broad (1 cm), dark lines with a narrow space (3 to 6 mm) between. Lay the image on a board, press it tightly with your exposure frame, and expose to sunlight for 3 to 5 minutes (just guessing). Then develop it. If the broad lines remain with resist on them, you have positive resist. If the narrow line remains with resist on it, you have negative resist. You can test for the presence of resist, if it is not obvious by looking at it, by adding a little of your etchant.Okey so:
1) Board brand is unknown, but it has a blue protective film on it.
Please give a link to that webpage. MG sells mostly liquids that need to be diluted. I use a solid (NaOH or KOH). I doubt what you have is solid NaOH or KOH. They absorb water from the air and look wet if left exposed for any lengthy period. So, I suspect your solid is either sodium silicate, sodium carbonate, or a mixture.2) As well unkown, it looks like salt, a bit bigger. On 10 grams I used 1 liter of water, like it says on webpage)
Did an image appear? If so, was it positive or negative?3) I put the board in developer and waited for image to appear.
What did you print onto, clear transparency or paper? If paper, did you treat it in any manner before using it as the mask?5) I use laser printer at my fathers office, don't know the brand.
That should be fine. The weight of the glass should be enough. I use small spring clips, as that allows me to handle the sandwich and flip it for double-sided boards.6) I use photo frame to keep it pressed togeather. I think it's regular glass, it's a cheep photoframe you can find everywhere. Glass is 2 mm thick.
That should be OK.7) I did it at 7 inches.
If it is fluorescent (spiral shaped), that is probably OK. They do come in different color temperatures nowadays. You want a high color temperature, if possible. Be sure to let it warm up and reach its full brightness.9) I used 15W energy saving light bulb. It dosen't says the brand but It's regular one you can find everywhere.
That is OK, but probably not necessary. Don't change now, though. Get the system working first.I work under red light.
OK, it sounds like you have a positive resist.
The way I found my exposure time was to print 4 or 5 copies of the same design on a transparency. Apply that to the blank PCB in the usual manner and cover all but one with opaque plastic (a piece of black trash bag works well). Expose one image, which will be your longest exposure, slide the shield to reveal the next one, so both will be exposed, and so forth. For example, if the exposure you initially used was 6 minutes and you have 4 patterns, I would expose the first pattern for 3 minutes, then each successive pattern for an additional 3 minutes. The longest exposure would then be 12 minutes (3 + 3x3 or twice the failed-run time) and shortest would be 3 minutes or half the failed run time. Of course, any timing sequence can be used. You simply want to bracket the time you used in the first run with exposure times that are sufficiently longer and shorter to tell whether your result was due to under or over exposure. My PCB's typically take 12 to 14 minutes of exposure.
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