On Mon, 13 May 2013 13:50:15 +1200, you wrote:
>I'll assume you're using the cheap readily available negative exposure
>dry film.
>
>As others have said, 15 seconds, sounds too short. I use about 2m30s
>with doubled tracing paper and UV leds, I think last time I used the sun
>(too big a board for my box) I put it out for about 5 minutes.
Take a strip of board, use a file or knife to score the board at about
half inch intervals. Put your image on top. Put a piece of cardboard
or something guaranteed opaque on top of the board covering all but
the last piece as marked by the scoring on the board.
Expose for half a minute. Move the cardboard over a notch, expose for
half a minute. Do this until you have the last notch on the board
exposed for half a minute. Each successive notch will be exposed for
30 seconds more.
You should get an idea of what the best exposure is fairly easily.
There's a piece of special film made for enlarging photographs with a
pie pattern on it. Each segment is a different shade of gray, letting
in progressively less light. One long exposure with that would do the
trick as well. Make sure you have detail as fine as you want for the
process.
Harvey
>
>You should be using Washing Soda (Sodium Carbonate) to develop somewhere
>in the region of 20g/Litre - 5 minutes and a bit of a rub. In fact I
>use it to strip as well (just warm up a stronger solution for stripping,
>soak 1/2 an hour, and the resist will float away), it takes longer but
>it's safer in all respects. Sodium Carbonate is available at your
>nearest supermarket, look in the laundry aisle for "natural" products,
>read the label, there'll be one there that is probably 100% Sodium
>Carbonate for sure.
>
>For hobbiest purposes, there is piles of lee-way with long exposures, if
>your artwork is sufficiently high contrast. When exposed, the traces
>are clearly visible. I'd suggest doing some small test pieces
>(something that has traces about as thin and closely spaced as you would
>want to use, like a SO16 breakout or something) to see how long an
>exposure you can get away with before you start seeing trouble. You're
>a hobbiest right so no need to be crazy precise, mark-one-eyeball it.
>Start with say 3 minutes, if it looks too-far-gone, try the next one 2
>minutes, if it looks ok, try one at 4 minutes. I think you'll be
>surprised just how long an exposure you can "get away with".
>
>Also, try using the doubled-tracing paper artwork. Way cheaper than
>acetate.
>
>
>
>On 13/05/13 02:07, dave_donlan wrote:
>>
>> Hi guys
>> I am using UV exposure method on clear acetate
>>
>> 15 secs exposure caustic soda developer about a 60 secs
>>
>> hydrochloric acid / peroxide etchant no bubbler just sloshing about
>> but the problem is the protective layer is coming off after a few
>> minuets of etching
>>
>> hydrochloric is 30%
>> peroxide is 9%
>>
>
>
>
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