Self etched PCBs: what trace width and spacing should I use?

Bricolo · 20th November 2004, 03:51 PM

Hi all,

I wanted to know what was the minimum trace width and spacing I could use with DIY PCBS. The printing is done on a laser printer.

And, what's a good trace width for line level audio use?

Thanks
Alex

Bricolo · 21st November 2004, 10:24 AM

Eagle's default setting is 16mil tracks with 8mil spacing

Isn't this a bit small?

chris ma · 21st November 2004, 12:01 PM

If you care to sign an oath with a lawyer and a witness to promise you are not going to produce this PCB for commercial gains or groupbuys then our senior citizens may entertain you.
Otherwsie I think you may be on your own due to no fault of your own of course!

The Butcher

Bricolo · 21st November 2004, 12:13 PM

It's for a personnal project, nothing to sell

pinkmouse · 21st November 2004, 12:49 PM

I have never used the laser method, but I suspect you might want to make up a test sheet for minimum line spacing, lots and lots of lines at different pitches and see what works with your toner and paper.

Bricolo · 21st November 2004, 12:55 PM

ok I'll try that

and what about the trace width? what's a good size?

chris ma · 21st November 2004, 01:16 PM

Hi,

I am not so sure about the size of the tracks and spacing if you have doubts regarding the software's default setting then go overkill for safety by manual setting if it is an option.

Let me share my experience with laser prints and iron onto the copper. I like to set the print to BOLD to ensure enough toner but when you have spacing too close to each other then there is a danger of BOLD would make a short! As pinkmouse stated try and experiment. At this stage you are not going to ruin the copper board since you can wipe it clean and start printing again..

hope this help

The Butcher

Bricolo · 21st November 2004, 01:36 PM

Now I'm not sure I understoor your advices, Al and Chris

Did you mean, printing and etching a test pcb, or only printing it and see the result on the transparency?

pinkmouse · 21st November 2004, 01:43 PM

I would print and etch, just to make sure. You only need to use a scrap of cheap phenolic board, doesn't need to be anything special.

Use a group of lines of one size, not just a pair, though, that will average out any inconsistencies in etching.

TroelsM · 21st November 2004, 01:56 PM

I have made a lot of PCB's with trackwidth: 15mills and track-to-track spacing: 12mills without any errors. The biggest source of error is usually the poor quality of the PCB that are available to me.

If there is the smallest scratch in the protective foil you'll get an error in you design. But the same goes for the quality of your print-work.

HP's Laserjet 4 (and maybe 5) are some of the best. They will print perfekt every time even for smaller trackwidths.

TroelsM

Denmark

20th November 2004, 03:51 PM	#1
Bricolo diyAudio Member Join Date: Nov 2002 Location: Grenoble, FR	Self etched PCBs: what trace width and spacing should I use? Hi all, I wanted to know what was the minimum trace width and spacing I could use with DIY PCBS. The printing is done on a laser printer. And, what's a good trace width for line level audio use? Thanks Alex __________________ Just remember: in theory there's no difference between theory and practice. But in practice it usually is quite a bit difference... Bob Pease

21st November 2004, 10:24 AM	#2
Bricolo diyAudio Member Join Date: Nov 2002 Location: Grenoble, FR	Eagle's default setting is 16mil tracks with 8mil spacing Isn't this a bit small? __________________ Just remember: in theory there's no difference between theory and practice. But in practice it usually is quite a bit difference... Bob Pease

21st November 2004, 12:01 PM	#3
chris ma diyAudio Member Join Date: Sep 2001 Location: Pickering, Canada	Help needed? If you care to sign an oath with a lawyer and a witness to promise you are not going to produce this PCB for commercial gains or groupbuys then our senior citizens may entertain you. Otherwsie I think you may be on your own due to no fault of your own of course! The Butcher

21st November 2004, 12:13 PM	#4
Bricolo diyAudio Member Join Date: Nov 2002 Location: Grenoble, FR	It's for a personnal project, nothing to sell __________________ Just remember: in theory there's no difference between theory and practice. But in practice it usually is quite a bit difference... Bob Pease

21st November 2004, 12:49 PM	#5
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	I have never used the laser method, but I suspect you might want to make up a test sheet for minimum line spacing, lots and lots of lines at different pitches and see what works with your toner and paper. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort


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21st November 2004, 12:55 PM	#6
Bricolo diyAudio Member Join Date: Nov 2002 Location: Grenoble, FR	ok I'll try that and what about the trace width? what's a good size? __________________ Just remember: in theory there's no difference between theory and practice. But in practice it usually is quite a bit difference... Bob Pease

21st November 2004, 01:16 PM	#7
chris ma diyAudio Member Join Date: Sep 2001 Location: Pickering, Canada	Hi, I am not so sure about the size of the tracks and spacing if you have doubts regarding the software's default setting then go overkill for safety by manual setting if it is an option. Let me share my experience with laser prints and iron onto the copper. I like to set the print to BOLD to ensure enough toner but when you have spacing too close to each other then there is a danger of BOLD would make a short! As pinkmouse stated try and experiment. At this stage you are not going to ruin the copper board since you can wipe it clean and start printing again.. hope this help The Butcher

21st November 2004, 01:36 PM	#8
Bricolo diyAudio Member Join Date: Nov 2002 Location: Grenoble, FR	Now I'm not sure I understoor your advices, Al and Chris Did you mean, printing and etching a test pcb, or only printing it and see the result on the transparency? __________________ Just remember: in theory there's no difference between theory and practice. But in practice it usually is quite a bit difference... Bob Pease

21st November 2004, 01:43 PM	#9
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	I would print and etch, just to make sure. You only need to use a scrap of cheap phenolic board, doesn't need to be anything special. Use a group of lines of one size, not just a pair, though, that will average out any inconsistencies in etching. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

21st November 2004, 01:56 PM	#10
TroelsM diyAudio Member Join Date: May 2003 Location: AARHUS. DK	My experience I have made a lot of PCB's with trackwidth: 15mills and track-to-track spacing: 12mills without any errors. The biggest source of error is usually the poor quality of the PCB that are available to me. If there is the smallest scratch in the protective foil you'll get an error in you design. But the same goes for the quality of your print-work. HP's Laserjet 4 (and maybe 5) are some of the best. They will print perfekt every time even for smaller trackwidths. TroelsM Denmark __________________ Need more time...

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