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| Dry film photoresist developing |
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| ZeroResistance:
Photoresist newbie here So I purchase some dry film photoresist its unbranded and the website I bought it from doesn't have any specific instructions of developing. However I found a instructable at this link https://www.instructables.com/id/Dry-Film-Photopolymer-for-making-circuit-boards/ So I went thu the usual steps of first printing a negative of my artwork on tracing paper with a laser printer. One sheet was not providing me high contrast So I printed on 2 tracing paper sheets and overlapped them. The I stuck the photoresist film on the copper side of the pcb and laminated it with a hot iron Then I kept my tracing paper over this with the printed side closest to the photoresist film. 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. I have attached the picture of the pcb. What did I do wrong here 1. Did I overexpose the film, so its difficult to develop now. 2. Is my developing solution too mild and do I need to do 3% concentration of sodium carbonate. Because I used distilled water at around 30 deg. |
| JackJones:
How did you place the tracing paper on it while developing? Because it really needs to be flat, I use a piece of glass and some clamps to keep it nice and firm on top of the pcb. I don't know how well developing it in sunlight works, but I'd wager it's not the optimal method and probably the source of your problems. You can buy a nail polish curer for about €10 and they work quite well. That's how I expose my photoresist. |
| ZeroResistance:
--- Quote from: JackJones on March 31, 2019, 08:04:11 am ---How did you place the tracing paper on it while developing? Because it really needs to be flat, I use a piece of glass and some clamps to keep it nice and firm on top of the pcb. I don't know how well developing it in sunlight works, but I'd wager it's not the optimal method and probably the source of your problems. You can buy a nail polish curer for about €10 and they work quite well. That's how I expose my photoresist. --- End quote --- After appling the photoresist film and laminating it. I stuck the pcb on a piiece an wood and then stuck the tracing paper an top of this with tape taking care that it was streched tightly over the pcb. The I kept this whole contraption in the sun. I don't understand how you expose with nail poilsh curer? Does it have uv or fluorescent lights inside them? |
| JackJones:
Nail polish curers use UV lamps to harden the polish. Luckily that is also what cures photoresist so you can use them for exposing photoresist. It only takes about a minute to expose photoresist through a piece of glass. You can get very fine details too, I regularly do 0.5mm pitch stuff. |
| ZeroResistance:
--- Quote from: JackJones on March 31, 2019, 08:20:16 am ---Nail polish curers use UV lamps to harden the polish. Luckily that is also what cures photoresist so you can use them for exposing photoresist. It only takes about a minute to expose photoresist through a piece of glass. You can get very fine details too, I regularly do 0.5mm pitch stuff. --- End quote --- Ok I guess is a sure shot way to get it to work unfortunately I will have to wait for it because I don't have one handy at the momont. Would fluorescent bulbs work. I can buy a few as they are readily available. |
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