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Old 2nd May 2007, 01:44 PM   #1
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Default photoresist

Hi to everybody,

i would like to know where can i get a good photoresist....but not for an astronomical price...i would say for about 20$ here ?
I have never made any board so i'm totally clueless.
I have just build my machine for the photoprinting with UV bulbs.

I would like to know if the photoresist is a very issue for this process.

I would be inclined to think that spry photoresist is worse.

Hope to receive some hints about this.

Best,
Stefano.
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Old 2nd May 2007, 02:31 PM   #2
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Just buy board ready coated, it's a lot more reliable and less hassle.
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Old 2nd May 2007, 02:47 PM   #3
GeeVee is offline GeeVee  Australia
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Hi Stefano.

Several years ago, i used the Electrolube PRP photo resist spray for PCB manfacture, and i gave very good results, but was very expensive ($35.00 here in Australia)

However, I dont use this anymore.

I now use the precoated boards by KINSTEN, which is excellent, and they are available all over the world.

Do a search on google, and you will find many sites explaining how to do it.

The only tricky part is to work out the exposure.
It can vary from 30min with a flood lamp to as low as 30 seconds with a proper UV lamp.

I use a face tannning lamp that I bought from ebay for $60.00, and it exposes a board in 2min at a distance of 250mm.

One of the best ways to determine the exposure time, is to purchase the cheap phenolic type board, and expose at 1min increments.

If you ever did photograpy, it is the identical procedure to when test strips were done.

The only this to remember that exposure time is also governed by the distance the lamp is away from the board.

Once you ave found the correct exposure / distance record it for future reference.

Hope this helps.

Regards,
George.
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Old 2nd May 2007, 02:53 PM   #4
GeeVee is offline GeeVee  Australia
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Hi Stefano.

Several years ago, i used the Electrolube PRP photo resist spray for PCB manfacture, and i gave very good results, but was very expensive ($35.00 here in Australia)

However, I dont use this anymore.

I now use the precoated boards by KINSTEN, which is excellent, and they are available all over the world.

Do a search on google, and you will find many sites explaining how to do it.

The only tricky part is to work out the exposure.
It can vary from 30min with a flood lamp to as low as 30 seconds with a proper UV lamp.

I use a face tannning lamp that I bought from ebay for $60.00, and it exposes a board in 2min at a distance of 250mm.

One of the best ways to determine the exposure time, is to purchase the cheap phenolic type board, and expose at 1min increments.

If you ever did photograpy, it is the identical procedure to when test strips were done.

The only this to remember that exposure time is also governed by the distance the lamp is away from the board.

Once you ave found the correct exposure / distance record it for future reference.

Hope this helps.

Regards,
George.
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Old 2nd May 2007, 09:18 PM   #5
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i have checked kinsten on the following website:

http://computronics.com.au/kinsten/prices/

the prices seem to be fine.
This business is on Australia so i don't know if they will ship here on Italy.
It's too late for me now...and i'm tired...so i 'll check this tomorrow.

Before to turn off th computer, i want to post and ask some hints on the PCB quality.
I don't know if anybody could explaint to me the different type of PCB available.
i don't know if there are different board with different quality of copper and thickness of copper.
If there are board with silver instead of copper or gold indeed.



Since i'm making this project for myself and i really want to obtain the maximum and consider all the minimum detail i would ike to pick the best board available.

Hope to learn something new...
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Old 2nd May 2007, 11:34 PM   #6
dangus is offline dangus  Canada
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There must be some local source; shipping photoresist could be a problem. It might have to go as hazardous cargo or something.

I think some engravers and lithographers use photoresists. Maybe if you check with dealers in engraving supplies you can find a source for photoresist. Or, just possibly, if you talk to someone who uses photoresist, they might let you have some dregs or leftovers.

If you can get your hands on the photoresist, it _can_ work out much cheaper than buying presensitized boards. But, getting the coating on evenly and not too thick is very tricky. With positive photoresist, I thinned it about 50%, spread it with a disposable foam brush, allowed it to dry, then baked it. I'm not sure how necessary baking was; I think I started doing that because I was impatient.

Thicker board stock is nicer to work with, and thicker copper looks better and obviously conducts better. Glass-epoxy board is stronger than phenolic.

I'm currently using UV fluorescent tubes, F15T8BL (if I remember correctly).
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Old 3rd May 2007, 02:04 AM   #7
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Hi Stefanoo !

You should be able to get "Positiv 20" in Italy and I think it should be less then 20 euro. I remember some nice electronics shops in Trieste, when I was there visiting, that might have something like that. Here's a link to some Positiv 20 info, perhaps you can go from there. http://www.crceurope.com/csp/web/Pro...ECTRONIC&lng=3

Dangus: Where do you get photo resist in BC?


Frank
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Old 3rd May 2007, 09:00 PM   #8
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i would prefere to find a photoresist that is not spray; i read that with the brush yu can spread it better.

I still as your help to figure out the differet type of pcb available.

FR4...thiket copper....silver plated....gold plated....

where can i find good quality pcb board to print with photoresist-UV bulb-acid?
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Old 3rd May 2007, 09:35 PM   #9
sek is offline sek  Germany
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Hi,

Bungard and Isel are some renowned local brands of precoated board material that I've had good results with.

Sebastian
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Old 4th May 2007, 06:45 AM   #10
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i found very interesting the first brand that you mentioned.
Did you order a small quantity from them?
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