1. Pre-sensitized boards (the come in several sizes )
2. Developer
3. I use the Ammonium persulphate and will NEVER EVER go back to Ferric Chloride (ick!) It is way cleaner and you can actually see the board as it is etched!
I use regular flourescent lamps for 9 minutes and they work perfect. In fact I have used a flourescent flood light for years and it works every time. I started to do this in a dark room and make sure your art is pressed firmly against your PCB or the traces get blurry and unusable. I am able to roll QFP packages easily such as the propeller chip. I get consistant usable results this way.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔ ·- Was it pin 11 or 26?· Hmmm....··I think the smell of smoke tells the whole story.· Must be 26.
Michael King
Application Engineer
R&D
Digital Technology Group
Developing the resist after UV exposure. The resist exposed to UV dissolves in the sodium hydroxide solution. The dish has to be agitated, it takes up to about 20 seconds.
Leon
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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle
It's not too late to stop this madness. Out of all those who have responded to your posts, most (perhaps even all but one, LEON) have pointed out sound, logical reasons not to do this youself. I don't know if there are rehab centers that treat "gluttony for punishment". If there are, I'm sure Google will help you find one.
-Phil
So bottom line Phil, anyone who is crazy enough to try this needs to check into rehab?? [noparse]:)[/noparse]
I tried making my own boards years ago with mask and etchant. My results were interesting, but not very usable. There was a thread where some stamp folks were going to build an XY-stepper with a drill for cutting copper ... don't know the results, but it seems that would be a friendlier process than etching.
Bean makes a compelling point on plated through holes with annular rings or "vias" ... not having to add a ton of jumper wires or 0-ohm resistors has great value. The number of vias, board dimensions, layers/character, and gold fingers used to be the most important factors in board cost. I guess that's calculated automatically by the layout software These days.
7 min from a black light at 8" has worked well for me using mg chemicals presensetized boards. You can do 8 mil resolution or so but it works best if you do a double transparency. Use the sodium hydroxide at a 20 to 1 ratio or less. It is better to be too weak than too strong or it will all wash off. It will take a little experimentation.
The Big guys use a form of oxidized hydrocloric acid to etch their boards. I think and there is info about that floating around but don't say I told you to do it. Wear Eye and skin protection with all this stuff if you do it.
If you are doing double sided boards and your time is worth money then use ourpcb. I ordered 2 sets of 25 boards delivered with soldermask and silkscreen for $188. They were about 6 sq in each. Thats hard to beat if your time is worth money and you like to use lots of vias.
Ok, well I went to fry's and it turns out THEY have all the stuff I need... I got some regular copper clad board and a presensitized board. I also got some Sodium Persulfate for the etchant, and one of those pens for drawing a circuit by hand(resist pen?). So I've tried a few little 1/2" square pieces out in the sodium persulfate and it seems to etch in about 30 minutes or so at room temperature... Seems a little long. As for the pen, it's Smile. Sometimes it writes and sometimes it doesn't, and when it does, I have to press kind of hard so it's a big fat line - very non-uniform to say the least.
A little off topic, but I have a circuit that has been routed on Eagle 5.1.0... I am looking at the board with the component symbols, but can't figure out how to export just the traces or artwork for use on a transparency to actually make the circuit. Any pointers???
The hot ferric chloride I use etches in 5-10 minutes with continuous agitation (rocking the dish by hand). Did you use agitation? Warming the etchant should help, as well. That's what I did when I used ammonium persulphate for etching. I put the etching dish in a larger container (an old washing up bowl) with about 1" of very hot water in it, which keeps the etchant hot. It also catches any splashes and spills. I do the etching in the kitchen sink, BTW.
Permanent waterproof marker pens (Staedtler makes good ones) work very well for hand-drawn boards. I used cellulose paint and a fine paintbrush, many years ago, when I first started making my own PCBs.
I don't know about Eagle, but the PCB software I use can output plots directly to a Windows printer, as well as to Gerber files.
Leon
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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle
Just curious if anyone has tried the HCl and H2O2 method? Wow... that sure does eat away the copper in a hurry. CHEAP too! A gallong of muriatic acid is something like $10 and hydrogen peroxide is what, $2?
Yeah, the fumes aren't too nice. That's why I'm doing this outside right now. I'm really amazed by it though. All I did was get one of those ultra fine tip permanent markers, and wrote a little something on it, left it in the mixture for ten minutes and bam. The copper was gone everywhere except where I wrote. Very nice and CHEAP!(and cheap is what I'm all about)
Well, I've done my first little PCB. It's a DIP adapter for an LMD18200(3A H bridge motor controller). I used sodium hydroxide as the developer, as per Leon's instructions of 12g/L. I know many say that the sun doesn't work, but here in Texas, we get PLENTY of UV. Apparently enough UV for 1 minute to develop the board in the NaOH. I used my HCl and H2O2 solution to etch and it's turned out beautifully for my first go. I'll post some pictures later.
Hi Phil, Why are you using hydrogen peroxide with the hydrochloric? Does it increase the oxidation rate perhaps? Can you point me to a site that describes the technique for mixing the solution? I presume you can re-use the solution if you top-up the acid. David
David, I have no idea how the reaction works. I'm no chemist, in fact, chemistry itself is blackmagic in my opinion, but this does work and it works very well. I have no idea how it works, but am very curious. I'm not so sure about topping up with acid. I think, somehow, the H2O2 is releasing it's oxyegn and becoming regular water. If anything, you may need to top up with the hydrogen peroxide. The reason I say it's the H2O2 is that the solution becomes a very vivid green color and copper oxide is green. The other reason I say this is that as I etch more copper, the solution doesn't etch as fast, but when I pour the liquid out onto some rocks/gravel, it bubbles vigorously implying the acid is still very concentrated. The reason I like this stuff, is that you can buy a gallon of HCl at a pool supply for under $10, and a couple gallons of H2O2 for the same price. This makes 3 gallons of etchant for about $20. The ratio of mixture that I have heard, and use, is 1 part Hydrochloric acid(muriatic acid), 2 parts hydrogen peroxide. The ratio may be stociometric, but I can't see how.
By the way, for anyone else, Sunlight seems to be a GREAT UV source. I left my board out in the sun with the artwork on it for about a minute, then put it into 12g/L solution of NaOH. Etched in about 2 minutes perfectly. Actually, my first go I put it in a solution of filtered drain cleaner - the kind that warns about Lye in it. Etches great. All in all, I guessing I'm doing a poor man PCB, but it worked out wonderful - especially for my first time! LOL
BTW, for anyone who wants to know about the chemical reaction that goes on - I was wrong. The product of the reaction was my second guess... Copper Chloride. This explains it a little.
Very interesting thread. Magic all the same, but interesting. The H2O2 is actually what oxidizes the board, while the HCl attacks the oxides... Good to know if you need to clean a copper board when its sat out for a while and oxidizes - soak it in HCl for a while and presto... Clean!
Post Edited (Philldapill) : 7/26/2008 3:59:02 AM GMT
Ah yes... Cu (copper) will not dissolve in pure HCL (hydrochloric acid) so H2O2 (hydrogen peroxide) is added as the oxidizer. After etching you end-up with green acidic cupric chloride, which can be re-used and eventually re-generated by adding more hydrogen peroxide or bubbling air through the solution (one of the links below has photos of the titration process). Eventual disposal seems to be a problem though, use NaHCO3 (sodium bicarbonate or baking soda). Where's my ph meter? Hmmm....
Wow, these are nice boards! I made a batch of 8 adapter boards - qty: 4 SOT-3 to DIP on each 0.7" x 0.8" adapter board. Yes, I know these are a little silly, but I've found many parts that I want only come in the SOT-3 size and wouldn't work for prototyping. So, I made a batch and shouldn't have that problem again. Man, these are nice and clean... Seriously, anyone want a board made for $0.50 a square inch(holes drilled upon request for $0.05 a hole)
Propeller.
(There at least this thread has something to do with the prop now!)
I recommend 1/32" MG Chemicals pre-sensitized boards. The boards are thin enough to cut with sharp scissors, but not so much that they lack structural integrity. The chemical MG coats their boards with is sensitive to a wider spectrum of light than just UV, so you don't need to go crazy looking for special lights. I use two 100W equivalent (26W actual) 4800K CFL's and exposure is done after eight minutes. We've been getting incredible resolution with these boards and photomasks printed on doubled up 3M Premium Inkjet Transparencies with an Epson Stylus Pro R800. We've made QFP sized pitches with the toner transfer method in the past, though it took a lot of effort.
Thanks Paul. I'm using the same pre-sensitized boards, so I guess I have to give credit to MG, rather than take it for myself. I'm using a small 18" blacklight for 7 minutes to expose them, and a solution of 12g/L sodium hydroxide. I too have gotten GREAT resolutiuon with this setup. My problem, however, is that if I have a tiny speck of dust on the transparency, it will show up on the finished board and possibly bridge two connections! The up side to that, is that I can GET resolution like that to make tiny tracks.
For my printer, I'm using some inkjet transparency(unknown brand - just some I had) and an HP Deskjet 6940. I reprint the transparency 3 times to ensure a good solid black image. The printer seems pretty good at doing an exact re-print as I seldom have any problem with one print not lining up with the previous printjob.
As for the etchant, as I said, I'm using HCl and H2O2. Common and cheap chemicals. The etch time takes about 5-7 minutes with a slight swirl here and there.
If anyone is interested, I can make a small quantity of PCB's for them for a near at-cost price. The boards I've made are great, but I'd like to get some more experience with the process before I start doing the QFP chip for the propeller, so if anyone wants some adapter boards, full circuit boards, or what have you, let me know and I'd love to get them made quickly, and cheaply. If I mess up on one, I'll do it over at my expense.
Thanks guys for all the input, even Phil and his "Noooo! Don't do it you nutjob! You'll be sorry you did!!!!" minions [noparse]:)[/noparse]
I too have etched my own double sided boards using similar methods. However the two problems that I have is that I have no way to tin the boards and I have to hand solder all vias. You about have to do a number of vias with at least one underneath the qfn which means a little difficulty keeping the via low enough. Without tinning soldering is a bit more difficult though not impossible. Have you figured out a way to do this Phil?
In regards to the vias, I haven't done them yet. I've only done single sided board, with a few jumpers, instead of the double sided approach. Once I start with double sided, I've thought about getting a fine stream of air to "push" some solder through to the other side. I'm not sure if this is how some do it, but that's what I would do. Plus, I'm using 1/32 board, so I doubt it should be too difficult. The surface tension of the solder alone should make it pretty easy with this size board.
I doubt that relying on solder alone to make a via is a very good scheme. Solder is not a desired 'mechanical' material to depend on for that function of making a dependable connection on a two sided board. May work many times, but to trouble shoot 'opens' in a via can be a hair-pulling experience. Visually may look proper, but internally the connection can be an open or intermittent connection. Even opening on temperature changes or pcb bending.
YMMV, as they say. Good luck on depending on solder to form a via. Better is to use a thin wire, ie: 30 gauge or so to form the 'via'.
Comments
You need:
1. Pre-sensitized boards (the come in several sizes )
2. Developer
3. I use the Ammonium persulphate and will NEVER EVER go back to Ferric Chloride (ick!) It is way cleaner and you can actually see the board as it is etched!
I use regular flourescent lamps for 9 minutes and they work perfect. In fact I have used a flourescent flood light for years and it works every time. I started to do this in a dark room and make sure your art is pressed firmly against your PCB or the traces get blurry and unusable. I am able to roll QFP packages easily such as the propeller chip. I get consistant usable results this way.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·- Was it pin 11 or 26?· Hmmm....··I think the smell of smoke tells the whole story.· Must be 26.
Michael King
Application Engineer
R&D
Digital Technology Group
Developing the resist after UV exposure. The resist exposed to UV dissolves in the sodium hydroxide solution. The dish has to be agitated, it takes up to about 20 seconds.
Leon
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle
So bottom line Phil, anyone who is crazy enough to try this needs to check into rehab?? [noparse]:)[/noparse]
heh..
OBC
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New to the Propeller?
Getting started with the Protoboard? - Propeller Cookbook 1.4
Updates to the Cookbook are now posted to: Propeller.warrantyvoid.us
Got an SD card? - PropDOS
Need a part? Got spare electronics? - The Electronics Exchange
-Phil
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'Still some PropSTICK Kit bare PCBs left!
Bean makes a compelling point on plated through holes with annular rings or "vias" ... not having to add a ton of jumper wires or 0-ohm resistors has great value. The number of vias, board dimensions, layers/character, and gold fingers used to be the most important factors in board cost. I guess that's calculated automatically by the layout software These days.
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The Big guys use a form of oxidized hydrocloric acid to etch their boards. I think and there is info about that floating around but don't say I told you to do it. Wear Eye and skin protection with all this stuff if you do it.
If you are doing double sided boards and your time is worth money then use ourpcb. I ordered 2 sets of 25 boards delivered with soldermask and silkscreen for $188. They were about 6 sq in each. Thats hard to beat if your time is worth money and you like to use lots of vias.
A little off topic, but I have a circuit that has been routed on Eagle 5.1.0... I am looking at the board with the component symbols, but can't figure out how to export just the traces or artwork for use on a transparency to actually make the circuit. Any pointers???
Permanent waterproof marker pens (Staedtler makes good ones) work very well for hand-drawn boards. I used cellulose paint and a fine paintbrush, many years ago, when I first started making my own PCBs.
I don't know about Eagle, but the PCB software I use can output plots directly to a Windows printer, as well as to Gerber files.
Leon
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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle
Post Edited (Leon) : 7/24/2008 9:41:37 AM GMT
http://www.fullnet.com/~tomg/gooteepc.htm
Leon
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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle
http://www.allelectronics.com/make-a-store/item/TEK-5/TECHNIKS-PRESS-PEEL-PC-BOARD-KIT/-/1.html
By the way, for anyone else, Sunlight seems to be a GREAT UV source. I left my board out in the sun with the artwork on it for about a minute, then put it into 12g/L solution of NaOH. Etched in about 2 minutes perfectly. Actually, my first go I put it in a solution of filtered drain cleaner - the kind that warns about Lye in it. Etches great. All in all, I guessing I'm doing a poor man PCB, but it worked out wonderful - especially for my first time! LOL
http://4hv.org/e107_plugins/forum/forum_viewtopic.php?21132
Very interesting thread. Magic all the same, but interesting. The H2O2 is actually what oxidizes the board, while the HCl attacks the oxides... Good to know if you need to clean a copper board when its sat out for a while and oxidizes - soak it in HCl for a while and presto... Clean!
Post Edited (Philldapill) : 7/26/2008 3:59:02 AM GMT
More links...
www.opencircuits.com/Chemical_Etchants#HydroChloric_Acid_.2F_Hydrogen_Peroxide
www.instructables.com/id/EUZET2WLCJEV2Z96TB/
members.optusnet.com.au/~eseychell/PCB/etching_CuCl/index.html
Thanks Phil, David
Propeller.
(There at least this thread has something to do with the prop now!)
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-Paul
For my printer, I'm using some inkjet transparency(unknown brand - just some I had) and an HP Deskjet 6940. I reprint the transparency 3 times to ensure a good solid black image. The printer seems pretty good at doing an exact re-print as I seldom have any problem with one print not lining up with the previous printjob.
As for the etchant, as I said, I'm using HCl and H2O2. Common and cheap chemicals. The etch time takes about 5-7 minutes with a slight swirl here and there.
If anyone is interested, I can make a small quantity of PCB's for them for a near at-cost price. The boards I've made are great, but I'd like to get some more experience with the process before I start doing the QFP chip for the propeller, so if anyone wants some adapter boards, full circuit boards, or what have you, let me know and I'd love to get them made quickly, and cheaply. If I mess up on one, I'll do it over at my expense.
Thanks guys for all the input, even Phil and his "Noooo! Don't do it you nutjob! You'll be sorry you did!!!!" minions [noparse]:)[/noparse]
In regards to the vias, I haven't done them yet. I've only done single sided board, with a few jumpers, instead of the double sided approach. Once I start with double sided, I've thought about getting a fine stream of air to "push" some solder through to the other side. I'm not sure if this is how some do it, but that's what I would do. Plus, I'm using 1/32 board, so I doubt it should be too difficult. The surface tension of the solder alone should make it pretty easy with this size board.
I doubt that relying on solder alone to make a via is a very good scheme. Solder is not a desired 'mechanical' material to depend on for that function of making a dependable connection on a two sided board. May work many times, but to trouble shoot 'opens' in a via can be a hair-pulling experience. Visually may look proper, but internally the connection can be an open or intermittent connection. Even opening on temperature changes or pcb bending.
YMMV, as they say. Good luck on depending on solder to form a via. Better is to use a thin wire, ie: 30 gauge or so to form the 'via'.
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Harley Shanko