Photoresist PCB's - Electronic Circuits Projects Diagrams Free

Boomslang · 30th July 2008, 06:41 AM

Hi

I've always been using toner transfer on magazine paper to make PCB's, but that's hard work. I decided to give photo resist a try.

Attached are 2 pics of small test boards I made. The circuit was printed on 120gsm tracing paper using a laser printer. The thinnest tracks are T8 size (the smallest Proteus will do). Exposure was done with good old sunlight @ 1 minute 10 seconds. Very happy with the results.

The 3rd picture is of the UV LED board I made, still waiting for the 200 LED's I ordered before I can give it a go.

Boomslang · 30th July 2008, 06:44 AM

PS: Making the UV board was also the first time I used carbide drill bits, and after 750 X 0.8mm holes the same bit is still going strong, only slightly starting to lift the copper on the edges of the holes... think it is still good for at least another 200 or so holes... worth the money.

Boomslang · 30th July 2008, 06:50 AM

Attached is a pic of the UV board I made using toner transfer. The pic was taken just before the board was etched.

picbits · 30th July 2008, 07:45 AM

I love photoresist PCB. Apart from one board where I had a faulty coating on it, I've always had good results.

Don't keep your developer for more than a couple of days (1 week at the most) as it tends to deteriorate very quickly and in some cases will just remove your photoresist straight off irrespective of how much you've exposed it (I learnt that the hard way).

**3v0** · 30th July 2008, 11:15 AM

Quote:

Originally Posted by Boomslang

Hi

I've always been using toner transfer on magazine paper to make PCB's, but that's hard work. I decided to give photo resist a try.

Photo resist is great.

Toner transfer can be faster and less work the photo resist. But you need better stuff then old magazine paper. See Pulsar link in signature.

jpanhalt · 30th July 2008, 01:56 PM

I have used photoresist for more than 10 years. My best results are obtained with an inkjet printer; however, since I use a laser printer for everything else, my inkjet cartridges would dry out. I tried an HP LaserJet on clear transparency (3M CG3300). The toner was not very dense. I found that I could go over the toner with black dry erase marker, let it dry thoroughly, then wipe it off with a soft tissue. The transparency was much denser after that treatment and worked better for the photoresist method. One image shows the treated transparency before wiping off the dry erase. The other image shows the untreated and treated transparencies. The untreated transparency, when used to expose a board, resulted in tiny holes in the copper from its lack of uniform opacity.

My preferred method for making transparencies is still inkjet, but the treated laserjet image works almost as well.
John

picbits · 30th July 2008, 02:00 PM

Thats a good tip about using the dry wipe marker.

I've found that using a Laser printer on transparency is just about adequate - I get small pinholes and larger areas aren't brilliant but ok for prototyping.

Will have to give the marker idea a go next time I'm passing a place that sells them.

jpanhalt · 30th July 2008, 02:12 PM

@picbits

As a hint, don't scrub back and forth either the marker or the tissue. You can scratch the resist. The solvent in the dry erase seems to soften the resist a little. I just lay on an even coat with he marker. Let it dry well ( >5 min), then wipe the excess off. If I need to wipe more than once, I turn or fold the tissue to get a fresh surface. The little curls of dry resist can also scratch the image.

I think any marker color will work, but my best results have been with black. It is more crumbly and comes off cleaner. The colors seem to contain dye and pigment.

John

Boomslang · 30th July 2008, 08:31 PM

Thanks, I will try the the dry marker as well when I get hold of one.

As a test I put a solid piece of laser printed sheet on a PCB, and let it sit in the sun for +-4 minutes.. which is about 4 times longer that needed and it still came out good when developed.

One thing I noticed while making toner transfers is the printer+toner you use. I have access to about 20 different printers at work, and some of the laser prints came out very bad/ full of pinholes.
ATM I am using a Lexmark X642 with toner density set to max, "transparency" chosen in paper options and "Enhance fine lines" selected.
It is allot darker than the 3 inkjets I tried. The tracing paper also holds the toner down better than tracparency paper on the test prints I did.

jpanhalt · 30th July 2008, 09:03 PM

Quote:

Originally Posted by Boomslang

One thing I noticed while making toner transfers is the printer+toner you use.

That is quite true. I always mention my brand of printer, because there are significant differences. My HP4101 mfp is great for documents, but lousy for transparencies, and I suspect for toner transfer too. My old LJ4 was better for transparencies, and I hear some of the other brands (Lexmarks) are quite good.

John

Boomslang · 30th July 2008, 09:20 PM

True... for toner transfers a LJ5 Plus worked well for me, but a LJ1100 was worthless.

whiz115 · 30th July 2008, 10:14 PM

Quote:

Originally Posted by Boomslang

I've always been using toner transfer on magazine paper to make PCB's, but that's hard work.

can you tell me about that? what you do and how you do it?

Boncuk · 30th July 2008, 11:35 PM

Hi All,

I've made PCBs using photoresist material since I don't know when. (started out with asphalt laquer

) Using transparencies of the thinnest possible thickness and as clear as a mountain creek is best.

If the 'film' is not all the way black where it should be there is the possibility to make a contact copy using photofilm (offered in many electronics shops) or touch up using an EDDING400 for thick traces and an EDDING800 for fine traces. That kind of film has a different pixel solution which covers most of the pinhead sized blind spots without influence on the edges of traces and pads.

Photoresist may be very much different using different brands. The best I know of is BUNGARD (http://www.bungard.de) which always has the same and EQUAL consistence of the photo layer. Exposure times will always be the same.

Using laser printers you might run into a problem just because of the kind of engineering. Many of those printers have a toner saving circuit which cuts back the toner if the software encounters large black areas. This results in pinholes within the copper area or even areas which might get overexposed since they are transparent.

Until now I used two different laser printers with best results even for double sided PCBs. (Scratching or cutting with a scalpel after development might damage the photoresist, resulting in a junk PCB)

The Epson EPL5700 had the toner saving option. It must be disabled printing PCB layouts using the highest possible resolution of 1,600X1,600 pixels.

Now using a FujiXerox DocuPrint203A it doesn't have that fancy option and prints clear deep black sheets of DINA4 format. (Its resolution is 1,200X1,200 pixels)

For a test make a small board sized 2X2 inches all filled with copper. The printed "layout" should be a solid black area. If there are still "clouds" visible try to reconfigure the printer setup or refer to the printer customer service for advise.

An excellent print is as black as an a..h... in a dark tunnel. (Fill the blanks

)

Regards

Hans

Boomslang · 31st July 2008, 06:15 AM

Quote:

Originally Posted by whiz115

can you tell me about that? what you do and how you do it?

If you google "magazone paper toner tranfer" you will get allot of hits.
Here is one: http://www.riccibitti.com/pcb/pcb.htm

Hero999 · 31st July 2008, 05:21 PM

How much did all those UV LEDs cost you?

I still think tubes are the most efficient and cost effective option at the moment.

The only good thing about the LEDs is that they last for longer but since they aren't used for very long periods of time this isn't much of a advantage.

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30th July 2008, 06:44 AM	(permalink)
Boomslang	PS: Making the UV board was also the first time I used carbide drill bits, and after 750 X 0.8mm holes the same bit is still going strong, only slightly starting to lift the copper on the edges of the holes... think it is still good for at least another 200 or so holes... worth the money. __________________ How To Ask Questions The Smart Way Last edited by Boomslang; 30th July 2008 at 06:45 AM.

30th July 2008, 07:45 AM	(permalink)
picbits	I love photoresist PCB. Apart from one board where I had a faulty coating on it, I've always had good results. Don't keep your developer for more than a couple of days (1 week at the most) as it tends to deteriorate very quickly and in some cases will just remove your photoresist straight off irrespective of how much you've exposed it (I learnt that the hard way).

30th July 2008, 02:00 PM	(permalink)
picbits	Thats a good tip about using the dry wipe marker. I've found that using a Laser printer on transparency is just about adequate - I get small pinholes and larger areas aren't brilliant but ok for prototyping. Will have to give the marker idea a go next time I'm passing a place that sells them.

30th July 2008, 02:12 PM	(permalink)
jpanhalt	@picbits As a hint, don't scrub back and forth either the marker or the tissue. You can scratch the resist. The solvent in the dry erase seems to soften the resist a little. I just lay on an even coat with he marker. Let it dry well ( >5 min), then wipe the excess off. If I need to wipe more than once, I turn or fold the tissue to get a fresh surface. The little curls of dry resist can also scratch the image. I think any marker color will work, but my best results have been with black. It is more crumbly and comes off cleaner. The colors seem to contain dye and pigment. John

30th July 2008, 08:31 PM	(permalink)
Boomslang	Thanks, I will try the the dry marker as well when I get hold of one. As a test I put a solid piece of laser printed sheet on a PCB, and let it sit in the sun for +-4 minutes.. which is about 4 times longer that needed and it still came out good when developed. One thing I noticed while making toner transfers is the printer+toner you use. I have access to about 20 different printers at work, and some of the laser prints came out very bad/ full of pinholes. ATM I am using a Lexmark X642 with toner density set to max, "transparency" chosen in paper options and "Enhance fine lines" selected. It is allot darker than the 3 inkjets I tried. The tracing paper also holds the toner down better than tracparency paper on the test prints I did. __________________ How To Ask Questions The Smart Way

30th July 2008, 09:20 PM	(permalink)
Boomslang	True... for toner transfers a LJ5 Plus worked well for me, but a LJ1100 was worthless. __________________ How To Ask Questions The Smart Way

30th July 2008, 11:35 PM	(permalink)
Boncuk	Photoresist Hi All, I've made PCBs using photoresist material since I don't know when. (started out with asphalt laquer ) Using transparencies of the thinnest possible thickness and as clear as a mountain creek is best. If the 'film' is not all the way black where it should be there is the possibility to make a contact copy using photofilm (offered in many electronics shops) or touch up using an EDDING400 for thick traces and an EDDING800 for fine traces. That kind of film has a different pixel solution which covers most of the pinhead sized blind spots without influence on the edges of traces and pads. Photoresist may be very much different using different brands. The best I know of is BUNGARD (http://www.bungard.de) which always has the same and EQUAL consistence of the photo layer. Exposure times will always be the same. Using laser printers you might run into a problem just because of the kind of engineering. Many of those printers have a toner saving circuit which cuts back the toner if the software encounters large black areas. This results in pinholes within the copper area or even areas which might get overexposed since they are transparent. Until now I used two different laser printers with best results even for double sided PCBs. (Scratching or cutting with a scalpel after development might damage the photoresist, resulting in a junk PCB) The Epson EPL5700 had the toner saving option. It must be disabled printing PCB layouts using the highest possible resolution of 1,600X1,600 pixels. Now using a FujiXerox DocuPrint203A it doesn't have that fancy option and prints clear deep black sheets of DINA4 format. (Its resolution is 1,200X1,200 pixels) For a test make a small board sized 2X2 inches all filled with copper. The printed "layout" should be a solid black area. If there are still "clouds" visible try to reconfigure the printer setup or refer to the printer customer service for advise. An excellent print is as black as an a..h... in a dark tunnel. (Fill the blanks ) Regards Hans Last edited by Boncuk; 30th July 2008 at 11:39 PM.

31st July 2008, 05:21 PM	(permalink)
Hero999	How much did all those UV LEDs cost you? I still think tubes are the most efficient and cost effective option at the moment. The only good thing about the LEDs is that they last for longer but since they aren't used for very long periods of time this isn't much of a advantage. __________________ I also post at the following sites: http://www.stop-microsoft.org http://www.heated-debates.com Screen name: Aloone_Jonez