| Electronics > Beginners |
| Dry film photoresist developing |
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| beanflying:
Have a good scan through some of Big Clives Videos from this search too https://www.youtube.com/user/bigclivedotcom/search?query=pcb lots to be learned with a few different exposure devices including the nail curing lamps. |
| Jwillis:
Its over exposed. Higher intensity UV at shorter periods works best.5 minutes in the box I made https://www.eevblog.com/forum/projects/diy-dry-film-uv-exposure-box/msg2036233/#msg2036233 Even considering trying shorter exposure time. Theirs also a period of holding time between laminating ,between exposing and between developing. Approximately 30 min between each stage.Each holding to be done with board covered from light and at room temperature. This PDF explains it well and when followed the process works much better.https://ir.nctu.edu.tw/bitstream/11536/74691/7/851507.pdf They mention DI water which is de ionized water but not really necessary.Just good clean low mineral water is fine.I have high sodium tap water but the difference is minimal to bottled distilled. Hope this helps |
| jmelson:
--- Quote from: ZeroResistance on March 31, 2019, 07:55:11 am --- I exposed it in bright sunlight for 10min. The I tried developing it in 1% sodium carbonate solution. (5gm of soda ash in 500ml of distilled water) but after 3 min I washed the pcb in water and say than only a few small spots had exposed copper. I did developing for another 3min and just a little most copper got uncovered. --- End quote --- The stuff I use is exposed by a bank of fluorescent black light bulbs (405 nm) for one minute. I use high-contrast silver film, but still have problems if the exposure is much longer than 1 minute. My developer is 35 g per US gallon, so your solution sounds about right. Jon |
| jmelson:
OK my method is to heat the developer solution to about 35 - 40 C, and then drop the board in. I wipe the board continuously with my fingertips which removes the softened layer, allowing the devloper to attack the layer underneath. I generally have full development in under 2 minutes. If your skin is sensitive to the devloper, then you can try using the softest brushes. After development is complete, wash the board for at least a minute in flowing water, and again wipe the entire surface very gently to remove any remaining resist "slime" so it doesn't dry back onto the copper. Jon |
| beanflying:
This Just in. Talking about issues with applying the film. From about 4.30 for the PCB part. https://youtu.be/ZE5JASv3XyY |
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