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How good is YOUR etching process?

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Steve Conner

Wed Nov 21 2007, 07:25PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Well, I'm impressed with Matt's results, considering they're made on the kitchen stove with ingredients from a dumpster! :P

I remember handing in artwork with much coarser traces for university projects, and the EE department's PCB lab still managed to screw them up.

Marko

Wed Nov 21 2007, 07:53PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

I only recently got into this stuff... but I found the ironing technique to be very grateful.
Actually what frustrates me the most is drilling holes in overly tiny eagle pads.
I have only drill press for this which is quite slow and imprecise.

Still I can do any SMT work I want without trouble. It's actually much easier than drilling a large number of holes for through-hole packages.

I haven't attempted to push any limits yet though... and my free time now is too short :(

Hazmatt_(The Underdog)

Wed Nov 21 2007, 09:45PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Okay, no problem.

This is my Inductive Heater controller for Alpha Process Systems, a company I do things for once in a while. It was never used seriously because Fred changed over to a more stable hot water bath.

The serial date is 2001, so you guys can see how long its been sitting on the shelf, quite a while. I shined up the date code so you can see it more easily. Each line has its colon intact from the dry transfer. I was really careful about this because I would have to re-route the major board, which was difficult. The serial, Mfg, which is me, and company artwork is clear and clean. It was critical because this was going to go to someone's lab, they had to have some form of serial number and what it was.

I also did the front panel artwork with circuit board dry transfers and lettering transfers on a clear transparency. That gets photocopied onto nice paper, spray glued or glue-stick applied to the frame, then laminated.

It came out very nice. The mixed analog/digital should have been vastly improved, but this was before my first uC class, so I think that explains a lot.

mikeselectricstuff

Wed Nov 21 2007, 10:41PM

Registered Member #311 Joined: Sun Mar 12 2006, 08:28PM
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Posts: 253

I do proto PCBs a lot using the traditional UV exposure method, laser printing on a Lexmark Optra at 600dpi ( 1200 dpi for really fine stuff). I'd normally expect to get good 10 mil traces with no breaks or shorts.
I'd say there are two really important things - 1) use tracing paper, not OHP transparency film. It's cheaper, and gives better toner density and adhesion, and 2) use a silicate based developer, not sodium hydroxide, as it;s way less temperature sensitive, and gives a huge margin between "develop" and "strip".
For tons more info on making consistently good PCBs, see my page at

Overclocked

Thu Nov 22 2007, 02:22AM

Registered Member #1056 Joined: Thu Oct 11 2007, 11:15PM
Location: CT, USA
Posts: 27

The smallest I can get to is 10 Mil, and thats using a laser Printer. I use either FeCl3 or Copper Chloride.

I dont do a lot of SMD soldering So, thats why it looks a bit crappy.

Tom540

Thu Nov 22 2007, 02:55AM

Banned on 3/17/2009.
Registered Member #487 Joined: Sun Jul 09 2006, 01:22AM
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Posts: 617

Avalanche wrote ...

I also use an inkjet / UV exposure and I have managed to get down to 15 thou for SMT, with quite clean lines. Could go finer, but I've never needed to!

It goes something like this...

1 - Print onto 'Staples' own brand overhead transparencies, with the printer on the highest resolution and *important* set the printers media type to 'Premium photo paper' *not* 'overhead/transparency'. (Reason is if you select the transparency, the printer tries to be clever and apply the ink in a bizarre 'micro grid' pattern, presumably to stop it from flowing. It really doesn't need to do this, you get much sharper lines with it set to photo paper. This is on an HP deskjet, not sure if it applies to others.

2 - Cut the thing out let it dry etc etc apply to FR4 photoboard ink side to board and expose to UV from 2 computer cold cathode tubes for 8 minutes (I use a piece of glass from a picture frame, on two blocks of 1.5" square wood with the tubes underneath

3 - develop, etch - drop board into paint tray and throw in the end of a running electric tyre pump (can be a bit messy but it helps speed things up a bit

)

That's some pretty good results you managed with toner transfer though, you have lots more patience than me! I gave up with that long ago when I realised I could buy inkjet transparency.

I guess it doesn't even need to be transparency either, only transparent to UV...

Thats exactly what I do and thanks for reminding me what brand of transparency to use. I completely forgot. I haven't made boards at home for over a year. I did the same thing at my old job as well and I'm pretty sure we made some 8 mil traces as well.

TheMerovingian

Thu Nov 22 2007, 10:54PM

Registered Member #14 Joined: Thu Feb 02 2006, 01:04PM
Location: Prato/italy
Posts: 383

I hate using ferric cloride. Too much time to etch, need to heat the batch, too messy, too polluting. I have switched to HCl+H2O2 obtaining better results (sometime need to diluite the Hydrogen Peroxyde or the batch soon overheats and evolves poisonous Cl2). I often use 16 mil traces (not in this case though). I use an HP inkjet printer with inkjet trasparency sheets. THe uv exposure is done using a 8W wood UV lamp (5' 30 sec exposure). Developing with 1% NaOH and etching HCl 12% - H2O2 35%. The exhaust ethant is mixed with the NaOH of the previous stage to precipitate Copper as hydroxyde/oxyde, filtered and then discarded as solid. I am using high quality pre-threated photosensible boards.

Derek_L

Fri Nov 23 2007, 02:39PM

Registered Member #1125 Joined: Fri Nov 16 2007, 09:13PM
Location: Edmonton, Alberta, Canada
Posts: 62

My etching? You guys want to know about how well I etch?
Ill give you a demo,
Take one of those 3 year old jumbo crayons, you know one of those ones you get a a fair. THe ones that are 2 feet long x 1" diameter. Yeah those ones.
Take that on a rally car race and draw on a sheet of waxed paper.
That is how good I am.
Professional, this guy right here.

ConKbot of Doom

Fri Nov 23 2007, 06:02PM

Registered Member #509 Joined: Sat Feb 10 2007, 07:02AM
Location:
Posts: 329

Derek_Lucksinger wrote ...

My etching? You guys want to know about how well I etch?
Ill give you a demo,
Take one of those 3 year old jumbo crayons, you know one of those ones you get a a fair. THe ones that are 2 feet long x 1" diameter. Yeah those ones.
Take that on a rally car race and draw on a sheet of waxed paper.
That is how good I am.
Professional, this guy right here.

cool, does that just iron right over onto the the copperclad?

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