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Posts posted by ThemisD

  1. Hey everybody.

    I'm trying to make my own homemade PCBs using one layer copper clad PCBs with pre-applied photoresistive film(and protective cover). I'm having problems making the film appear correctly. Here is the process I follow from the begining:

    I use 1 15W UV lamp for about 3 mins. I have printed the circuit twice on tranparent paper and place them on top of each other to avoid unwanted gaps.
    Then I dip the PCB in worm water (50C-70C, 300ml) with about 1g of Sodium hydroxide (NaOH) and i leave it there for 1 min .

    I tried different "UV exposure times" from 1-6 mins and I changed the NaOH amount of the water, 0,5g-2g.

    Sometimes once I dip the PCB in the water-NaOH solution the traces appear (blackish) on the board and then they desolve in the water in seconds. Also when I go to the actual etching there is either no traces (all copper gets etched) or the film is intacted (no copper gets etched).Is that because I left the pcb too long under the UV light and it "burned" all the film, or is the solution to strong and disolve all the film?

    Once I managed to get good results but I didn't write down the exact "recipe" since then I tried half a dozen of PCBs but nothing. :-\

    PS I use a modified scanner with 1 UV lamp, the distance between the glass where I place the PCB and the lamp is about 2cm.

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