DIY PCB Idea

vttom

Senior Member
When it comes to making my projects more permanent, I'm never sure what is the best appraoch for DIYing a PCB.

I'm not a fan of etching my own circuit boards. No so much the etchant part but the drilling. I don't own a drill press, and even if I did, can't stand the thought of drilling hole after hole in my PCB.

I usually wind up using one of these. But they really only work for the simplest of circuit topologies.

Today I got to thinking.. What if I got one of these generic PCBs, and drew in my traces with a conductive ink pen (like this)? Routing my project would be like a game of connect-the-dots. This would also solve the problem of drilling, and the copper-plating would take care of the complaints I've seen with these pens where they're not really very solderable.

Has anyone tried this? I wonder if the pen is too wide-tipped or the ink too runny to make 0.1in pitch wiring difficult to pull off?
 

RexLan

Senior Member
Might just as well wire-wrap if you use the drilled PCB.

Pretty simple task to drill the boards if you have a Dremel and their little drill stand. I can drill a hundred holes in 10 minutes.
 

Dippy

Moderator
I don't even use a drill stand. I find hand jobs real easy.

oh the conductive paint idea has been kicking around for years and pops up every now and then.
I had a feeling that someone , somewhere developed a screen print conductive method (? ecelectic ?).

And then of course, some conductive paint/ink is more conductive than others.
Good luck. I'll stick to etching and drilling. Far more robust and reliable :)
 

Rickharris

Senior Member
I don't even use a drill stand. I find hand jobs real easy.
Huh? - really!

:)

At home I still frequently use veroboard or strip board. Even for relatively large Pcbs it works for me.

Debugging can be a real pain though if you get it wrong.

At school we did for a while draw our circuits on a CAD system at strip board pitch then print off the drawing and glue on the non-copper side to guide component placement. Works.
 

MartinM57

Moderator
I prefer doing it dead-bug stylee....(I don't actually, but it sounds Dippy-esque to say it)

I'm sure I saw an Instructable about using one of those pens and post-it notes to make a (very flexible) PCB
 

John West

Senior Member
I usually do a surface mnt layout in FreePcb then etch the bd. The trick I use is that I do the layout for standard through-hole parts - then bend the leads out on the ICs and solder them down. I end up needing just a few jumpers for places where I can't route the traces under components.

It makes for a very easy to solder, very reliable and clean layout.

The disadvantage is that the bds end up being substantially larger than SMT bds and somewhat larger than through-hole bds as well. But I have lots of scrap bd material, and I hate drilling holes, especially when I end up having to both top and bottom solder anyway.
 
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vshortt

Senior Member
I, too hate drilling holes. It can be tedious and messy if you have a lot of them to do. I normally also try to just go the SMT route. You can get just about anything in SMT form factors these days. Gets rid of the drilling altogether.

Oh, and using a homebrew for the board etching makes the etching process go 10 times faster, is dirt cheap and biodegradable. I can make 4 cups of a Hydrogen peroxide/muriatic acid solution for less than 10 cents U.S. and it cuts a 3x5 board in less than 5 minutes.

With boards being that easy to make, I've not used a "pegboard" in a LONG LONG time. buy the copper blanks in bulk on that big auction site and go to town. This method can cut uSOP and uMAX lands perfect every time.
 
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vshortt

Senior Member
I use the toner transfer method, just have to be very specific as to what paper you use, and make sure you have your iron NICE AND HOT. take your time tranferring the patterm.

Here's what I do:

FIRST: put on a set of nitrile gloves -it protects the copper from your finger oils, protects for fingers from copper dust, and will allow you to reach into the etchant should you need to get the board situated. That last bit is especially important if you're using a homebrew etchant like I am.

1) I scuff the copper with 220 grit sandpaper (many people will say thats too rough, but it works perfect every time for me without jagged edged traces). I've tried pre-etching it in solution, using 1,000 grit wet-or-dry sandpaper, using a scotchbrite pad, steel wool... nothing performs as well as 220 grit.

2) I wipe the entire board down with alchohol and dry thoroughly (this removes oil residue and sanding residue at the same time. after this don't touch the board anywhere you want the transfer to stick.

3) turn the Iron up as HOT as you can get it with the steam off. Then Iron the paper on, I usually iron until I can see the traces faintly. This guarantees good adhesion. It will take some time to get it right. I go over a few times with the iron flat, then use the tip to push on the paper as I slide it around. I know I have good adhesion when I can see the traces through the paper.

4) soak it in warm water, wait until the entire piece of paper is thoroughly soaked through then give it 5 more minutes to loosed the fibers. Work in the middle, working your way out by rubbing your fingers against the soaked paper, it will come off in little "rolls" one layer at a time. It doesn't take long to get them all off. Once you're down to jut a few straggling pieces of paper between traces, brush gently with a toothbrush to get them off. Don't worry about making all the traces perfectly black. When the board dries, they will most likely be a frosty white because there are paper fibers stll stuck to the toner. Don't try to lift the entire sheet from the edges, that almost guarantees pulling traces off the copper, then you get to start over!

5) let it dry - air dry or pat gently. DO NOT USE WARM AIR TO DRY. If you do, you run the risk of "reflowing" the toner, or remelting it, causing it to lose what little adhesion it has... bad juju!!

6) drop it in the ethant and have a frosty beverage! I like to put a couple of pieces of soda straw on the surface of the etchant and then set the board down on them and let the board push them into the liquid. This causes the board to be held up off the bottom of your etchant container and makes the bottom side etch faster. The etchant I use is simple and cheap to make: 2 parts Hydrogen Peroxide and one mart Muriatic acid. I've made batches from 1/4 cup total (2 tbsp peroxide, 1tbsp acid gets close to 1/4cup) to make little bitty boards all the way up to making 4 cups for cutting a 10 inch by 5 inch board. - all with the same results. fantastic!!

I use "Goof off" to get the toner off the board, comes off in one swipe. I am sure other things will work too, but Goof off is cheap. I think laquer thinner also works, I've never used it. Goof off works too well to try anything else.

If you're doing double sided boards, the process is much the same, except when you get the first side done, drill a couple of "centering holes" flip the board over (I usually put it on a legal pad, or spiral notebook or something to keep the heat from transferring directly to the counter), push a couple of pins into the corresponding cetnering holes on the bottom side sheet of paper, then lay the bottom sheet down, lining the holes up with the pins. Get as perfect as you can.

Don't remove the pins until you have run the iron over the shet a few times. THEN remove the pins. This tacks the sheet down, keeping it form sliding away when you push on the iron. Then iron as you did the first side.

Same tactic of getting it into the etchant using soda straws as a spacer.

There are a million recommendations for paper our there, I know. BUT: here's what works for me, and the paper is readily available: I use HP Semi-Gloss Inkjet paper. Product Q5498A. I've had pretty good success with many different types of paper, but this one seems to work the best, especially on larger boards that are in the drink longer. Other papers will transfer just fine, but the traces tend to pull up in long etchings. This HP paper doesn't give me that problem.

Another tip would be to make sure you have your laser printer on the darkest setting possible... as dark as it will go. you want a lot of toner to transfer. make sure to spray the traces with clear laquer when you're done soldering on it. I've also use mop-n-glow to do the same thing, works great and is super cheap. Tarnish will set in FAST if you don't. then you have a noisy, useless board.

I don't use and PCB layout software. all my boards are made in Corel Draw (yes, oldschool..) mainly because the blacks are TRULY black. It's a littler harder to do and you have to know the mechanics of how to set up a board (which is what most PCB software does automatically) but it works for me. works darn well for me in fact.

Like I said, I can get .5 to .25 traces without any issue whatsoever. Soldering was a challenge until I got my hot air unit and some solder paste, not I can put a uMAX 8 lead chip on the board in a matter of seconds and it's perfect every time. I get results like this:

pardon the "gooey look" thats from the flux - I had JUST finished soldering this up. These are all .25 traces. the pins around the perimeter are 2.54mm standard spacing so I can plug the chip into a breadboard. This board is about the size of 2 postage stamps, so we're WAY zoomed in here.



This is one of THE very first boards I did in homebrew etchant, took 5 minutes. This board is now running a winch and some lights on my truck. Been in service for over a year now.


This is a closeup (microscope) of one of the traces on the board above.



Sorry for the long post, I hope that helps. there are a TON of write-ups on how to make these things. If anyone thinks that a picture tutorial would help, I'd be happy to make one if it can be stickied on here.
 
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eclectic

Moderator
@vshortt

18.23 - 19.44
All that reading / composing / editing / posting
in 81 minutes!

Genuine applause.

And yes, it would make a nice tutorial.

e
 

Minifig666

Senior Member
Thanks very very much for that massively in depth guide. I've seen tutorials before, but never that good. The effort is greatly appreciated! That's definably in order of printing.
Previously I used my school's laser printers as I only have an ink jet. Now my new school charges extortionate and would never let me change the paper. Anyway, my question is would it work if I was to print on my inkjet then have it done on a photocopier would that work?
 

Andrew Cowan

Senior Member
If you used a proper photocopier that uses toner, I can't see any reason why it wouldn't work.

Andrew
 
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vshortt

Senior Member
you can pick up a great, brand new laser printer now for under $100. But that may be too expensive still. So, look for a used one. Doesn't matter how fast, or how big of a piece of paper it will use.

For the longest time I used an antiquated HP Laserjet 4L and it did perfectly. It was way too slow to print everyday stuff, but it was perfect for making trace transfers, so I just loaded it with photo paper and used it exclusivley for that. I think I paid all of $35 for the printer and another $50 for the toner cartridge. The printer gave out before I ran out of toner though. I must have put hundreds of sheets through it.
 

ckoehn

Member
Brother laser printercopiers use a toner that melts at high temperatures. The best brand to use is a Canon copier. Their toner melts at a lower temp.
 

lbenson

Senior Member
Inspiring write-up, vshortt. I just ordered the Canon ML-1665 laser printer ($49.99 US from Amazon) and the nitrile gloves and the HP paper. I hope the toner is dark enough. I couldn't figure out on the Canon site how to get the manual to see what kind of adjustments were possible.

You said the etchant is biodegradable--how do you dispose of it?

Thanks for this contribution.
 

vshortt

Senior Member
Thats the beauty of the etchant, just dilute it with water when you're done and pour it right down the drain.

here's a little note though: if you have a stainless steel sink you're going to be pouring down - DON'T - the etchant WILL STAIN stainless... think about it... it's designed to eat metals, right? - trust me, I learned this the hard way!!! realy though, I usually take it out the garage, put it in a 5 gallon bucket and fill the bucket with water. Then just pour it out on the driveway - totaly harmless that dilute, thought I don't think I'd drink it, LOL.

You can actually use the same solution over and over in a single session. Eventually it will stop etching though (it gets copper saturated). There are ways to reinvigorate it, but it's just easier to dump it out and start new.

You will know the etchant is working when you see a "cloud" or "film" coming off of the board in that classic statue of liberty green color and bubbles begin to form where the trace meets the board. Don't panic, the bubbles won't dislodge the traces of you've taken your time in the iron-on phase. The boards will etch from the outside in, so you will see the first signs of progress on the edges. It happens fast enough that you can usually watch it happen, if your patient. I've heard that you can even speed the process up more by heating the solution in a microwave or double-boiler, but I've never tried it. If you blow up your microwave, don't blame me!! LOL

When you mix the chemicals, always - ALWAYS remember, pour the ACID INTO THE HYDROGEN PEROXIDE - that's a basic chemistry rule. Always pour acid INTO something else, never the other way aound. The reason is simple: if you get a little too carried away and splash some out, if your pouring INTO acid, you will splash ACID out. If you're pouring into H2O2 (hydrogen peroxide) then you just splash hydrogen peroxide out - no biggie.

Make sure and mix the chemicals well. You know you have it right when the container gets slightly warm. The fumes are going to be very strong like acid very close to the top of the container, so don't stick your nose in it. the fumes are very heavy (I won't go into the chemistry details, trust me) - so they tend to sit in the container. It won't stink up the hose. Heck, it won't even stink up the room!! I've cut boards on one kitchen counter and made dinner on the other. Eventually the fumes will totally subside... but they're really not a factor to begin with.

I use household plastic bowls /tupperware/gladware to etch boards it. the etchant is non-reactive with anything but metals. So, any bowl thats NOT metal will do just fine. I've even etched tiny boards in a 1/4 cup measuring cup! LOL. Give the bowl a little shake every once in a while. The etching process makes hydrogen bubbles, and you want to break them free of the board to get an even cut.

When you're done, use a plastic or metal utensil you don't care about to get the board out (or if you're following my direction above, just put the gloves on and grab it). Then make sure to wash the board off in the sink to get the etchant off. I usually go right to the 'goof off' at this point and wipe the whole baord down, then send the dishes through the dishwasher or just wash normally (and thoroughly) and they're food safe again.

Really, at this dilution, the Muriatic acid is virtually harmless, but I still respect it. It's a strong acid all by itself. At full strength it will eat through concrete, so when you portion it out, make sure of what you're standing over. I have a few marks in my garage to prove this point! LOL.

The acid can be picked up at any home improvement store or pool supply place (It's used to bring pH down in pools and to scrub plaster pools). Just keep it tightly bottled. I think a gallon of it costs about $15 or so and that will last you a year if you're a heavy PCB maker like me. ( I make a couple every week it seems). the nitrile gloves can be found at any hardware store or even Wal-Mart, find them in the paint section. I STRONGLY recommend AGAINST getting regular latex gloves. The solution will cause holes in the latex fairly quickly and it taints the etchant, making the cutting process take longer, or stop altogether.

Thats a great point about Brother printers. I didn't even think about that. The HP' and the Canon's use a toner that melts at 280F, they are the ones to use!!!

Oh yeah, one more thing, if you have a color laser printer (like me! LOL) you can makecolorfull silkscreen's for the top of the board too (or just black)!! I do it all the time, you just cant do it in white like the "big boys" can. The toner adheres very well to the raw fiberglass/bakelite/substrate found in most PCB blanks. simply iron it on in the same fashion as before. When done, go ahead and clear-coat the top of the board before you start soldering, unless it's an SMD board. you can then just clear coat most of the SMD components along with the "silkscreen" you put on. just make sure to iron the silkscreen on before you start soldering!!!!

Victor
why this post doubled is beyond me. sorry everyone.
 
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premelec

Senior Member
Understated Acid + mix effects

Note that with exothermic reactions e.g. sulfuric and water pouring the water into acid can cause severe boiling [can happen with bases too..] - not just a bit of splash but a very hazardous situation... WEAR YOUR SAFETY GLASSES! ALWAYS! [from a one eyed guy who knows...]
 

vshortt

Senior Member
Note that with exothermic reactions e.g. sulfuric and water pouring the water into acid can cause severe boiling [can happen with bases too..] - not just a bit of splash but a very hazardous situation... WEAR YOUR SAFETY GLASSES! ALWAYS! [from a one eyed guy who knows...]
This is very true, however the hydrogen peroxide changes the acid's chemical makeup, making it ion hungry (If I remember right) and it loses this tendancy. I've even tried taking a fresh batch without ever etching anything and putting it int he bucket and filling it. The chemical makeup changes it so much that it's practicaly inert at this point.

But I do agree.. safetly goggles are a good thing to use... it IS ACID after all.

Muriatic acid itself is just an aqueous solution of Hydrogen chloride Gas - adding the Hydrogen Peroxide adds hydrogen molecues and somewhat "stabilizes" the acid, making it copper hungry. (good grief, I sound like chemistry geek, not an electronics geek! LOL)
 

John West

Senior Member
Ok, thanks. Yes, I will use another school's photocopier.
Double check the size of the copy against the original. I've used photocopiers to make iron-on PCB etching masks before and found that the copies were seldom exactly the same size as the originals.

Perhaps newer copiers don't have that problem - but older ones may. Maintaining size accuracy wasn't initially a critical parameter for simple copy work.
 

manie

Senior Member
Muriatic Acid is in fact Hydrochloric Acid also known as HCl. It produces fumes (a lot !) which is HIGHLY corrosive ! I would not use it in the kitchen while making food. In fact the fumes will taint most metal objects, especially mild steel. Even storing a 5L container in the garage can make your tools rust ! I store mine outside, tightly capped. When your HCl and H202 mixture turns deep green, it can be rejuvinated by passing air through it for a period of time. Just slowly bubble air from a compressor through it for a few days and its back to use again. One will have to look at the economics of that though ??? To get rid of mine when I'm finished etching, I just add (slowly !) the leftover NaOH (sodium hydroxide) developer to the etching dish. The old developer neutralises the HCl forming a solution of NaCl (table salt) and water. Now and ONLY now, is it safe to pur down the drain..........
 

Minifig666

Senior Member
Thanks for the extra advice guys!
I don't know about outside NY (the one in the UK) but I emailed my county council waste service and they offered me a monthly pickup service, for free. Well that was for FeCl3 anyway.
 

TAMeyer

Member
Printing White?

Thanks Victor, a great post.

I use similar processes, and your finer points are sure to help.
You are correct, 220 grit gives a consistent, quality result.

I do it all the time, you just cant do it in white like the "big boys" can.
Well, maybe not but you can get the same effect with one more step using this:
http://www.pulsarprofx.com/pcbfx/main_site/pages/products/toner_foils/toner_foils.html

Print the stencil to the board as you outlined above. Then, cut a sheet of "White TRF Foil" slightly larger than the board. Wrap the foil around one edge of the board and run through a laminator, or iron as you mentioned.

Once cool, peel back the "foil" (actually a plastic film), the white material sticks to the pre-printed toner. Touch up with masking tape per the site's FAQ.

Thanks

Terry
 

vshortt

Senior Member
Okay, I did a little more reading here. This thread has sparked a curiosity in a routine I've been using for years to etch boards, when you're wrong, your'e wrong - and in this case I appear to be quite so... so in the interest of preventing the spread of bad info, I humbly retract my statement saying it's safe to pour down the drain and offer this information and a general apology to those reading this. However, I still believe this is THE best way to etch boards, by far and will continue to use the method with a new disposal plan.

Perhaps putting it right down the drain isn't such a great idea. The reason why is that you're create Copper(II) Chloride, which is toxic. Levels of copper chloride in drinking water must be measured by the EPA at 5ppm or lower. Which is very very low. I suppose if everyone in a medium sized city started etching boards and dumping the etchant down the drain we'd have a problem. Will one person in East Finchley contaminate the entire water table beneath London? I seriously, seriously doubt it, but still, perhaps giving this advice isn' the best thing to do. So, for now, I will start putting the used etchant in a five gallon bucket outside and put the lid on it. Hopefully I can find a more earth-friendly way to dispose of it. Since I can't guarantee a tight fit on the lid, I will have to store it outside of the garage, which is not a problem. Seem thats the bad thing about the internet, it's really easy to get mis-information and pass it on without realizing it's bad info. So for that I apologize. There is one obscure mention on the web about turning the acid mix into a solid for proper disposal, but so far I've not come up with a good way to do that.

Yes, you can rejuvenate the etchant by bubbling air through it - you can also rejuvenate it by adding a small amount of Hydrogen Peroxide- but it never seems to etch as good as a fresh batch, perhaps once I get enough of it in my 5 gallon bucket outside, I may try it. I have a couple of old air-stones from a fish tank that would be perfect for this, but really- it's so cheap to make, why bother? The answer would have to do with conservation I suppose. Managing resources and not toxifying your surroundings.

Someone mentioned adding developer to it to make it inert, which is great... but I don't think that's something the average joe would have lying around in their garage to use. I still contend that this stuff is safe enough, with the mixture of the two chemicals, the HCl isn't saturated enough by the H2O2 to produce meaningull amounts of chlorine gas (which what the 'don't smell the fumes' people are worried about) - Yes, HCl fumes alone are corrosive... and left over a long enough period with the lid off, it would corrode everything in your garage. The same can be said for Chlorine tablets for pools and septic systems.

What I can tell you is this: I have 3, 1-gallon jugs of Muriatic acid in my garage from when my house was built (we acid-washed the tile for a rustic look, looks great!) each jug was opened about 3 years ago, so the factory seal has been broken ever since. all three sit neatly next to my gigantic snap-on tool box filled with all grades of tools from snap-on torque wrenches to the cheapest chinese made ratchet and sockets - and everything in between and nothing has corroded or rusted out. This includes an axe, 2 shovels, a post-hole digger, 3 rakes, a hoe, etc...that is hanging on the wall ABOVE the bottles, a wheel barrow that sits on the other side of the bottles, the two vehicles that are parked in the garage, a 4-wheeler, 6 bicycles (we have 4 kiddos), and a whole host of other miscelaneious stuff including an entire toolbox full of old nuts and bolts... folks NOTHING has corroded. If you just keep the bottles tightly sealed, you will be fine. (the bottles are in a locked chemical cage along with several other things to keep little hands out ;))

It's important to keep in mind the amounts of the chemicals we're talking about using. We're not mixing a 250 gallon vat of this stuff. We're going to end up with, maybe... MAYBE a cup for the average etching. You don't need 5 gallons to cut a 3x5 board... you need just enough to cover the board plus one in on either side. I don't do the math... what I do is take my board when it's ready to etch, put it in the bowl or container I am going to etch in and then fill it with water to where it looks about right. I then take the board out, pour the water into a measuring cup and round to the nearist 1/4 cup or so... that tells me how much etchant I need to make.

If I need to make a whole cup, I pour in 2/3 cup hydrogen peroxide and 1/3 cup acid... easy cheesy.

If I need 1/2 a cup, I pour in 3/8 of a cup of Peroxide and 1/8 of a cup of acid.

There are some websites out there that say to mix the two 1:1, I've never done that before, but I can see how that would work. When you do that you're making Acid Cupric Chloride, but I've nevertried it.
 

SAborn

Senior Member
Guys if you laser print or photo copy onto the waxy shiney sheet that stickers come on like laser print labels it will make removing the paper very easy, no nead to soak it in water and rub off the paper.

All you do is iron it onto the board as normal and then stick it into the fridge or freezer to cool down and it will then peel off the paper (sticker backing) as clean as.

Once you have tried this method you wont stuff around with plain paper ever again.

I use to pick up a cheap pack of laser labels when ever i seen them cheap and peel the labels off and turf them in the bin.

It is handy to keep a few labels and use them to stick a piece of cut up backing sheet to a plain sheet of paper to feed through the printer so not to waste a full sheet of backing on a small board.

Also found sign makers will give away large rolls of the backing sheet the vinal come stuck to that they cut the lettering out of when making signs. (its free)
 

1968neil

Senior Member
I quite frequently use the Toner transfer method, works well for me.
As u say vshortt taking your time and good good preparation is the key.

Personally i used old magazines (im a cheapskate !) the ones with the glossy pages, its also good recycling !
I print directly onto it with a laser printer and simply iron it on to the pre-prepared copper board.

As for drilling its pretty quick with a drill stand, i use the dremmel drill and stand and to date ive not managed to break a single pcb drill even the tiny ones!
I do find that fibreclass boards are not so kind to the drill they blunt very quickly, but as i say i have had pretty consistent results using this method.
 

Attachments

Rickharris

Senior Member
I have read - but not tried - that you get a similar result to SAbourn's idea by using the waxy freezer paper sold to wrap things for the freezer.
 

1968neil

Senior Member
not sure about the waxy paper ? wax-laser-printer-heat ? :confused:
I may be wrong, have never tried it ! I wasn't sure about the glossy paper either ! lol but it works.
 

RexLan

Senior Member
I have read - but not tried - that you get a similar result to SAbourn's idea by using the waxy freezer paper sold to wrap things for the freezer.
I don't think that will work at all ... wax will melt before toner will transfer.

I just use plain old photo paper and have for many years ... works fine for me with my HP LaserJet. I have a 4 Plus and it is 600 dot.
 

Dippy

Moderator
I'll stick to photo method.
Works 100% , no pits, no cockups, no accidents and edges far far better than iron on.
Same negative can do a million PCBs.
Luxury. :)
 

Grogster

Senior Member
I don't like the toner-transfer method.

In my case, it did not work - weather I did not have black enough toner etc, but I found the whole process frustrating, damaging to the copper laminate, and only yielded average results - when it worked! :p

DON'T GET ME WRONG - it may work fine for others, but my PERSONAL opinion if asked, would be not to use that. Use the photographic UV method - much more consistent results.

The only thing you really need over and above a photocopier or laser printer, is a UV box and some clear transparency film(MUST be rated for printer/copier use, NOT OHP plastic, as it will melt inside the printer.), and these are easier to make then you think. Search the net for UV exposure box - you could even make it a PICAXE project, and build the timer out of a PICAXE! :)

You also need some UV sensitive PCB - Kinsten is a common brand and is available on the net from many suppliers - quick, easy and gives great results.
 

vshortt

Senior Member
I don't like the toner-transfer method.

In my case, it did not work - weather I did not have black enough toner etc, but I found the whole process frustrating, damaging to the copper laminate, and only yielded average results - when it worked! :p

DON'T GET ME WRONG - it may work fine for others, but my PERSONAL opinion if asked, would be not to use that. Use the photographic UV method - much more consistent results.

The only thing you really need over and above a photocopier or laser printer, is a UV box and some clear transparency film(MUST be rated for printer/copier use, NOT OHP plastic, as it will melt inside the printer.), and these are easier to make then you think. Search the net for UV exposure box - you could even make it a PICAXE project, and build the timer out of a PICAXE! :)

You also need some UV sensitive PCB - Kinsten is a common brand and is available on the net from many suppliers - quick, easy and gives great results.
If you're damaging the copper laminate, then you're definatley doing something wrong. I don't know how you could possible do that, but...

It definatley sounds like you may have not had things set up right. But I'm glad you found a system that works!!

For me the main factor is the cost. the Photoresist method is 10 times as expensive as the toner method. which means I can afford to make 10 times the mistakes! LOL
 

SAborn

Senior Member
For me the main factor is the cost. the Photoresist method is 10 times as expensive as the toner method. which means I can afford to make 10 times the mistakes! LOL
I dont agree, the last i looked a 300 x 150mm photo resist board was listed at $4.00 and there is a lot of boards in that.

Photo resist is far the better system and i have used both and make many boards.

I do use toner transfer for the odd double sided board as i find it easier to align the 2 sets of art work.

I mainly use toner transfer for the silk screen text labels on the top of the board.

The best advice on using any type of paper through a laser printer, it to check it first with a hot iron and if it handles the heat then it should be fine through the printer.
 

John West

Senior Member
I'd like to try the photo-resist method, but I already have several square feet of blank bd material that I'd prefer to use up instead of spending money on pre-sensitized bd material of some size or shape that may not be what I need.

Not only do we each have different requirements for the size and number of bds we fabricate, we also each have different pocketbooks and different degrees of care and patience with bd materials.

Certainly the best method to use is the one that works that we're comfortable with.
 

ckoehn

Member
Maybe someone who uses photo resist should give us a step by step example of how they do it. I would like to know from someone who has had experience.

It just seems to me that it is more expensive and a lot more work. My boards usually turn out OK the first time.
 

vshortt

Senior Member
I think thats a great idea!! I'd love to see a step by step write-up on how to make 'em.

The only thing that stopped me from trying them out was the sticker shock on the printer-safe transparencies.. .$50 for a box of 50 or or something like that at my local office supply store. I now realize that you can get them much cheaper online though.

Perhaps this is worth a re-look for me. This is where the write-up would come in very handy!

V
 

SAborn

Senior Member
Maybe someone who uses photo resist should give us a step by step example of how they do it. I would like to know from someone who has had experience.
I done an article some time back on a different site here.

http://www.thebackshed.com/windmill/articles/MakingPrintedCircuitBoards.asp

At times i make as many boards in a week as many of you make in a year, but often only make what i need when i want it.

The advantage is it is simple and consistent results, for a fraction more, but i find i buy precoated resist board for as cheap as i can buy plain copper clad board for.

Also another link for the UV light source i use is here.

http://www.thebackshed.com/windmill/FORUM1/forum_posts.asp?TID=2303&PN=6
Go to the page 2 of the link

instead of spending money on pre-sensitized bd material of some size or shape that may not be what I need.
I normally buy sheets 300 x 400mm but you can buy any size you want, and only need to cut it to size with a hacksaw as you would with any other PCB sheet.

It comes with a plastic layer over the board you remove when you want to expose the image, otherwise its just a sheet of PCB as normal.

This method works as well with bubblejet printers (even better) as it dose with laser or photocopies.
 
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JoeFromOzarks

Senior Member
Attached is a PDF of the goodies and processes I use in making PCB’s. I use the Positive Resist/Developer method and I can boast a 99% success rate!! (That 99% figure is a guess, I’ve built over a hundred PCB’s using this method and the couple I wasted are hanging by my bench…)

Testimonial: (from memory, but I’ll juice it up a bit for entertainment purposes)

Awhile back, a friend called (very late in the day!) needing a timer circuit, about an hour and fifteen minutes ON, about fifteen minutes OFF, 24 hours a day, seven days a week, unattended. The circuit would operate a 12VDC relay to cycle on an off a 120VAC 2-amp device, he had the relay and all of the stuff to connect it. The board had to fit in a space of 8” long, 3” wide and 12” of depth. (I don’t have any components 12” tall so that wasn’t an issue.) The relay was off the PCB, mounted on a DIN rail. Power was 12VDC supplied from a regulated power supply also mounted to the DIN rail. Precise timing was not critical. We discussed the other details, nothing was out of the ordinary.

He asked if I could have it built in a week.

No problem.

I started boiling water to heat up the FeCl3, turned on the fluorescent light (exposure unit,) the laser printer and plugged in the soldering iron.

Using DipTrace, I cobbled up a circuit based on the PicAxe 08M and a ULN2803 to drive the relay. A 7805, a bucket full of decoupling caps, a couple of resistors, an LED to indicate “seconds” and another to indicate “power on” and the programming circuit based around the BAT85 wrapped up the design – based on the parts I had in stock. I exported to DipTrace PCB, set the board dimensions to 2.25”x6”, positioned the components and let it autoroute, then tweaked the traces. (I don’t like square turns, and I want the DC-in on the left, the logic outs on the right, standard USA layout.) So far, about 45 minutes invested. Start the timer.

I cut the transparency in half, printed the DipTrace PCB to it, exposed the PCB, etched, drilled the component and mounting holes, and mounted the components. Elapsed time, a little over 45 minutes. Fired up the Programming Editor and wrote a quickie program. I hooked up the 2803 outputs to a reed relay, placed the relay across one of the key contacts of an old USB keyboard, wrote a little VFP8 program to record the true on/off times of the PicAxe code (averaged about 76 minutes ON, 14 minutes OFF if memory serves) and let it run overnight.

I called him the next morning to pick up the circuit, he was amazed! From concept to functioning PCB in about an hour and a half. It’s been running non-stop for about a year and a half, maybe two years – it’s still running, and replaced a fried $2000US timer board. He had my board quicker than the factory could ship him a replacement! I was such a PicAxe newbie then…

(Since then, I was struck by a car, I don’t get around as well as I used to. Still, at my age I cannot afford to waste time producing garbage PCB’s!)

:) joe
 

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Dippy

Moderator
Printer plus transparency or tracing paper. Staples OHP transparency for copiers/lasers is fine and quite cheap.
UV exposure device.
Tray + developer.
Tray + etchant

1. Print your transparency. 20 seconds
2. Contact UV expose. 90 seconds
3. Develop. 30 seconds
4. Rinse. 30 seconds.
5. Etch. 10 to 20 minutes.
Want another board?... then goto Step 2.
Oh, you use toner transfer. OK heat up Mum's iron again and print another sheet (medium + toner costs?).

Costs:
Here in UK, Rapid is one of the cheapest for QUALITY PCB copper clad board.
Someone showed me some cheapo CH stuff from an Ebay vendor - truly awful, lumpy and crappy.
Looked like the copper had been applied with a painbrush.

Maybe going from SRBP CHCHcrappo to top quality Euro/UK/USA FR4 is 10x the cost but then again some of us have some pride in their work ;)
In UK a 160 x 100mm top quality UK made Fotoboard2 is just under £3.

Quality.
I have seen several examples of iron-on. OK i suppose, but edge and fine track resolution is NOWHERE near photo etching (when using QUALITY) board.

Then, of course, you need to factor in an honest figure for success rate....
And an honest figure for developer costs.
SENO 4006 (pro grade developer concentrate) is £15 per litre and makes 20 litres.

Before this I was shot in the shin and in the back of my other leg - seeing as we all seem to going on about injuries from the past.
 
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