Axis Operating System Blog

Hi, heres how to make pcbs THIS GUIDE IS FROM:

Most info from: http://www.riccibitti.com/pcb/pcb.htm

Some info from: Me

Some info from: My friend Gordon

Some info from: http://www.instructables.com USER: The Real Elliot

Comment if you have ny thig to say or just want to genraly comment, my keyboad is scs)

Notes:

- Ink printers DO NOT work.

- Magazine paper works best, i tried glossy photo paper, semi glossy photo paper, and matte photo paper, magazine paper works best.

- Dont use magazine covers, and try to get pages with no words.

- For etching use Copper Chloride in Aqueous Hydrochloric Acid Solution (HyPo x 2 with PA x 1) 

- try to make sure your design has small circles in all four corners so you can drill holes to align double sided designs.

- for double sided designs, do one side first, then the other, and keep another piece of paper on the top and bottom, and also put a small piece of tape inbetween the paper and magazine paper.

- the tape will stick the paper together and make it work well.

- I used double sided copper clad board from lees electronics on main st vancouver.

- if you do use double sided copper remember to scrub both sides as both sides have a protective coating you must scrub off.

- you can either use a saw and sanpaper to cut the pcb, laser cutter, water jet cutter, but i found a simple foot laid works best.

So heres the guide below:

Required materials		I used…	Where to find
	Magazines or advertising brochures       (More on this later).	IEN magazine / TV programme magazine Mail-order catalogue Travel agent’s brochures	Free in your mailbox
	Laser printer      Alternately, a photocopier should work	Samsung  ML1710 with original toner cartridge. Inkjet printers/copiers don’t work.	Attached to your PC
	Household clothes iron	Tefal Acquagliss 70s (dismissed unit, vapour was broken)	Ask mummy
	Copper clad laminate	FR4 laminate 1.6 mm thick (35um copper)	Radio Shack
	Etching solution	About 1 liter of muriatric acid, and one liter of hyrdrogen peroxide (do not mix)	Radio Shack
	Kitchen scrubs	Spontex “Azione Verde”	Grocery store
	Thinner (e.g. acetone)	Nail polish remover. Most solvents used in painting will do.	Grocery store
	Plastic coated wire	Plastic insulated copper wire, 1 mm diameter solid core (about 1 meter/3feet)	Electrical store

You need also: a blade cutter, scotch tape, sandpaper, kitchen paper, cotton wool, vice, hacksaw.

 

How it works

Laser printers and photocopiers use plastic toner, not ink, to draw images. Toner is the black powder that ends up on your clothes and desk when replacing the printer cartridge. Being plastics, toner is resistant to etching solutions used for making PCBs – if only you could get it on copper! 
Modifying a printer for working with copper is out of question, but you can work around it with the toner-transfer principle. Like most plastics, toner melts with heat, turning in a sticky, glue-like paste. So why not print on paper as usual, place the sheet face-down on PCB copper, and melt toner on copper applying heat and pressure? 
Almost right. Right now you got paper toner-glued to PCB copper. Last step is to find a way to remove paper leaving toner on the copper, and you’re done. 
I must credit Thomas Gootee for finding a solution putting glossy, inkjet photo paper in his laser printer. He found that the glossy coating dissolves in water. As most of the toner does not penetrate the glossy surface, you can easily remove the paper support with water: the gloss dissolves and you can remove paper. 
Clever, isn’t it?

Unfortunately, the kind of paper used by Thomas is being replaced by new, improved, WATERPROOF (!) photo paper. This is good for your photo prints, but doesn’t work anymore for PCBs.

While searching for more information on the subject, I found a newsgroup thread that suggested replacing expensive inkjet photo paper with glossy paper recycled from magazines. Magazines use ink, not toner, for printing, so previous printing shouldn’t affect the process. Another great idea! I tried it and worked so well that I decided to spread the word. Read on for a complete tutorial and my hands-on tips.

Finding the right paper

The perfect paper should be: glossy, thin, and cheap. The kind of stuff that looks lustrous and shiny when new, but so cheap it quickly turns into pulp when wet. If you ever found a mailbox full of squashy mail on a rainy day, you already know the answer: paper used for most mail advertising and magazines fits perfectly the requisites. I tried pages from the free advertising magazine IEN,catalogues , travel agent’s brochures, TV programme magazine, and all worked well. I don’t expect great difference using paper from most magazines. As a rule of thumb, if humidity in your bathroom turns your magazine in bad shape, it should be OK. If the humidity on your fingertips is enough to feel a sticky sensation while touching its gloss coating, it should be OK. Feel free to experiment: almost any glossy magazine paper will work. I like thin paper over thick one, and prefer recycled paper over new paper.

Paper preparation

I discard pages heavily printed, preferring pages with normal-size text on white background. Although ink usually does not transfer on the PCB, heavy print of headlines sometimes accumulate so much ink that some gets on copper.
Cut the paper to a size suitable for your printer. Try to get straight, clean cuts, as jagged borders and paper dust are more prone to clog printer mechanism. An office cutter is ideal, but also a blade-cutter and a steady hand work well. 
Be careful to remove all staples, bindings, gadget glue or similar stuff, as they can damage printer’s drum and mechanisms.

 

Printer setup

Laser printers are not designed for handling thin, cheap paper, so we must help them feeding the sheets manually instead of using the paper tray. Selecting a straight paper path minimizes the chances of clogging. This is usually achieved setting the printer as if it were printing on envelopes.

You want to put as much toner on paper as possible, so disable “toner economy modes” and set printer properties to the maximum contrast and blackness possible. You want to print your PCB to exact size, so disable any form of scaling/resizing (e.g. “fit to page”). If your printer driver allows, set it to “center to page” as it helps to get the right position using a non-standard size sheet. 

Printing

Disclaimer: your laser printer is not designed to handle this kind of paper. Feeding your printer with paper other than special laser printer paper could damage it and potentially voids the warranty. So you are warned: do it at your own risk.

Print your PCB layout as usual, except you must setup the printer as described above and you must print a mirrored layout.

This is my PC thermometer circuit printed on IEN magazine paper. Notice that it is a mirror image of the circuit (the word PCTHERM is reversed). Placing some text helps recognizing when the layout is mirrored. Text will read straight again once the image is transferred on copper. If you look it very closely, you can see that toner is not opaque enough to 100% cover the words underneath, but this won’t affect etching.

 

How to cut raw material

PCB material is fibreglass like, and a trick to cut it effortlessly is to score a groove with a blade cutter or a glass cutter. The groove weakens the board to the point that bending it manually breaks it along the groove line. This method is applicable only when cutting the whole board along a line that goes from side to side, that is you can’t cut a U or L shaped board with it.
For small boards, I lock the PCB material in a vice, aligning vice edge and cut line. I use an all-aluminium vice which is soft and doesn’t scratch copper, if you use a steel vice protect copper surface with soft material. 
Using the vice as a guide, I score BOTH board sides with a blade cutter (be careful) or another sharp, hardened tool (e.g. a small screwdriver tip). Ensure to scratch edge-to-edge. Repeat this step 5-6 times on each side.
Bend the board. If groove is deep enough, the board will break before reaching a 30 degrees bend. It will break quite abruptly so be prepared and protect your hands with gloves.
To make paper alignment easier, cut a piece of PCB material that is larger (at least 10mm/0,39 inch for each side) than the final PCB.

Cleaning the board for transfer

It is essential that the copper surface is spotlessly clean and free from grease that could adverse etching. To remove oxide from copper surface, I use the abrasive spongy scrubs sold for kitchen cleaning. It’s cheaper than ultra-fine sandpaper and reusable many times. Metallic wool sold for kitchen cleaning purposes also works. Thoroughly scrub copper surface until really shiny. Rinse and dry with a clean cloth or kitchen paper.

Preparing for transfer

To make paper alignment easy, cut excess paper around one corner (leave a small margin though). Leave plenty of paper on the other sides to fix the paper to the desk. As the board is larger than the final PCB, there is large margin for easy placement of paper on copper.

Turn the iron to its maximum heat (COTTON position) and turn off steam, if present. While the iron warms up, position the materials on the table. Don’t work on an ironing board as its soft surface makes it difficult to apply pressure and keep the PCB in place. Protect table surface with flat, heat-resistant material (e.g. old magazines) and place the board on top, copper face up. Lock the board in place with double-adhesive tape. Position the PCB printout over the copper surface, toner down, and align paper and board corners. Lock the paper with scotch tape along one side only. This way, you can flip the paper in and out instantly.

Iron it!

Flip out the paper, and preheat copper surface placing the iron on top of it for 30 seconds. Remove the iron, flip back paper into its previous position over the copper. It is essential that paper does not slip from its position. You can also cover with asecond sheet of blank paper to distribute pressure more evenly. Keep moving the iron, while pressing down as evenly as you can, for about one minute.

Remove the iron and let the board to cool down.

Peeling

 

This is the fun part. When the board is cool enough to touch, trim excess paper and immerge in water. Let it soak for 1 minute, or until paper softens.

 

Cheap paper softens almost immediately, turning into a pulp that is easy to remove rubbing with your thumb. Keep rubbing until all paper dissolves (usually less than 1 minute). Don’t be afraid to scratch toner, if it has transferred correctly it forms a very strong bond with copper.

 

The board with all paper removed. It is OK if some microscopic paper fibres remain on the toner (but remove any fibre from copper), giving it a silky feeling. It is normal that these fibres turn a little white when dry.

 

Magnified view of the tracks, these are 1206 pads and SO8 SMT pads, connected by 20 mils tracks. Some white fibres show up on the black toner surface.

The hanger tool

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The optimal way to etch is keeping the PCB horizontal and face-down (and possibly stirring). This way dissolved copper gets rapidly dispersed in the solution by gravity. Stirring keeps its concentration even, so the solution close to the PCB does not saturate and etching proceeds quicker. Unfortunately it is not easy to keep the PCB in place in an highly corrosive acid. This hanger is my best attempt to solve the problem. I made it with plastic-insulated copper wire. The wire must have a rigid core, but must be also easy enough to adapt to the board by hand without tools. Core diameter of 1 to 2mm is fine. Give it the form of an “arm” (the handle) ending with 4 “fingers”.

Each finger has a ring tip that fits a corner of the board. Close fingers around board corners: now you can use the handle to splash the board into the etching solution, stir, and inspect how etching proceeds.

Etching

***NOTE FROM AXISOS< THIS IS A LONG GUIDE AND IS MADE BY INSTRUCTABLES ON STOP USING FERRIC CHLORIDE****

Ferric chloride is a traditional home-use circuit board etchant. It’s easy enough to come by, and the Ferric by itself is no big environmental problem. However, once you’ve etched a board with it, you’re left with a solution with a bunch of copper chloride in it. This dissolved copper is an environmental problem, and you can’t just pour it down the drain (legally) — you’re supposed to take it to a hazardous waste facility. (For instance: How to Dispose of Ferric Chloride in this FAQ. )   

Wouldn’t it be nice if there were an etchant that you could re-use indefinitely so that you don’t have to worry about disposing of the copper, and that could be made in lifetime supply for like $10.00 with ingredients bought at hardware and drugstores? (And it’s prettier too.)

I got seven words for you: Copper Chloride in Aqueous Hydrochloric Acid Solution! (Exclamation point!)

But how’re you going to get CCiAHAS? Conveniently enough, by starting out with a simple two-ingredient starter etchant, and doing a bunch of etching. 

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For the starter etchant itself, you only need two ingredients: hydrochloric acid and hydrogen peroxide.    

(OK, actually three. But the third one’s copper. See the chemistry section for an explanation.)

Hydrochloric (muriatic acid, “pool acid”, etc.) is available at a hardware store. The acid I got is 31.45% (or 10M) and should run around $5 per gallon. Which is more than you’ll ever, ever need. 

The peroxide is normal 3% for mouthwash or cleaning cuts, and can be bought at a drug store for $2-3 for a big bottle. 

You’ll also need a non-metallic container that fits your PCB and two standardized measuring cups. 

As long as you’re in the hardware store, pick up some acetone if you don’t already have some. It’s useful for removing the etch resist. (That’s for another instructable.)

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Measure out two quantities of hydrogen peroxide and pour it into your non-metalic container.   

Measure out one quantity of hydrochloric acid and pour it in. (”Do like you oughta, add acid to water” to minimize the chance of an out-of-control exothermic reaction.)

Be careful with the acid. This stuff (at 10 molar) is strong. Mine fumed a bit when I took the cap off. Don’t breathe it directly, and be sure you’ve opened the kitchen window. 

The starter etchant you’ve just made, on the other hand, is not so bad — around 3M HCl with a medium-strong oxidizer. I find it doesn’t fume much at room temperature when I’m re-using a batch. 

That said, you’ve got to be very careful to keep it away from metal — especially your stainless-steel kitchen sink. It’ll eat the stainless coating right off. Keep plenty of water flowing at all times when you’ve got any of this (even a drop) near the sink. 

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Toss the PCB into the solution and it’ll take off.    

If this is the first time you’re using this batch of solution (and I presume it is), it’ll etch super-fast. This small board took only 2 minutes. Yikes!

Since I use a deep container, I tend to swirl it around as it etches. This stuff is so active, though, that I’m not sure it’s necessary.

Keep the window open for ventilation because the starter solution gives off a little chlorine gas. (The end-etchant gives off much, much less.)

Also, note how the etchant gets greener over time as it eats away the copper. This is good news.

What’s happening is that you’re dissolving the copper from the board and turning it into cupric chloride. In the long-run, the cupric chloride will be doing most of the etching (instead of requiring disposal). For now, just watch your solution turn light green. Next time you use it, the color will deepen.

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(Note: I’m an economist, not a chemist. Please leave a comment if you’ve got any corrections and/or additions to this stuff!)   

I stumbled on this idea when I saw this website: Etching with Air Regenerated Acid Cupric Chloride by Adam Sechelle. Cupric chloride can be re-used indefinately by topping up the acid levels and adding oxygen (bubbled in from the atmosphere). Sounds cheap and environmentally friendly to boot. 

The website’s got a lot of good chemistry info on cupric chloride etching. His data on etching speeds is great, and his simple titration procedure for maintaining the acidity of the solution is pretty nice. 

To make the cupric chloride solution, he dissolves a bunch of copper wire in hydrochloric acid, and mentions maybe using hydrogen peroxide to speed up the oxidation, but doesn’t go into detail.

Which got me thinking. You didn’t have any cupric chloride yet, but you can make it by dissolving copper. Dissolving copper is the name of the etching game. So we can make one etchant that makes another etchant that’s infinitely re-chargeable. Elegant. 

Turns out that hydrochloric/peroxide is a common home-brew etchant (and I’ve re-re-invented the wheel, again) but I guess that people got so used to throwing away their “spent” etchant that they don’t think about re-using it. The whole point of this instructable is that you don’t throw it away, but use the dissolved copper forevermore as your long-run etchant.

Here’s what’s going on chemically:

Before there’s much copper dissolved in the solution, Cu + 2 HCl + H₂O₂ -> CuCl₂+ 2H₂O is the dominant net reaction. That is, the extra oxygen in solution from the peroxide is oxidizing the copper metal, in presence of the acid, to make copper (II) chloride. That’s our starter etchant. The resulting CuCl₂ shoud be a nice emerald green color.

After you’ve dissolved a lot of copper into the solution, and used up all the peroxide, the copper chloride does most of the etching for you: CuCl₂ + Cu -> 2 CuCl. That’s the end etchant.

Eventually you etch so much that you convert all the CuCl2 into CuCl, which doesn’t dissolve copper (and is a yucky brown color). As long as you’ve got enough acid in the solution, you can simply add more oxygen to re-oxidize the copper(I), making more copper(II) chloride and water: 2 CuCl + 2 HCl + O -> 2 CuCl₂ + H₂O. And then you can etch again.

Bottom Line:

Two things to maintain: CuCl₂ levels and acid levels.

CuCl₂: After all the peroxide is used up, and the solution starts turning brownish, you’ll have to add oxygen to regenerate the solution again: toss in a few more capfuls of peroxide or bubble air through the solution or swirl it around vigorously, or just pour it into an open container and wait. It’s easy to tell when you’re ready to etch again, because the solution turns green. 

It’s also impossible to add too much oxygen by adding air, so bubble/swirl to your heart’s content. If you’re using peroxide to add oxygen, be sparing — a little goes a long way, and it’s mostly water so you’re diluting your etchant by adding it.

Acid: Note that HCl is being consumed in the starter etchant and the regeneration reactions. So we’re going to have to add a bit more acid as time goes by. If you notice that it’s harder to re-green your brown etchant, it’s probably time to start thinking acid. 

I’ve tried the titration described on Adam’s site a couple times, and it’s pretty easy but requires an accurate scale and pure lye (back to the hardware store…). It’s easier to just toss in a capful of acid every few batches of boards, which seems to do the trick for me. 

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Once you’re done etching, pour the etchant back into your storage bottle, rinse off the board, flux, drill, populate, and solder.    

Some final notes here:

1) You can make quite a bit of this stuff very easily, and since you’re re-using it, there’s no real reason to skimp; put plenty of etchant in your “tank.” When you use too little FeCl etchant, for instance, it can get saturated with copper and slow down which can result in long etching times and pitting or undercutting or worse. When I’m etching a board with copper chloride, I’ll pour a couple extra inches of solution into the container. It’s reusable anyway, and the extra exposure to oxygen just regenerates it. Live large.

2) Don’t make too much. As you keep re-using the solution, you’re going to need to add a little more acid and a little more peroxide every once in a while. If you’ve got a 750 milliliter container, start out with less than 500 milliliters of solution. Give yourself some room to grow over time. After all, the main point is to avoid having to dispose the copper in spent etchant.

3) If you’ve got too much volume of etchant (it will happen eventually) you can evaporate out the extra water by putting it in a shallow (non-metallic) pan or beaker or whatever and letting it sit for a while. This concentrates the copper in solution, giving you a stronger etchant. It’ll also re-oxidize some of the copper for you, a bonus. Remember when you’re adding the peroxide that you’re actually adding 97% water.

4) The linked website suggests that the acid levels in the etchant are not critical as long as there’s some acid in solution to do the CuCl₂ regeneration. The amount of CuCl₂ (vs CuCl) present is easy to diagnose by the color of the solution. Add oxygen to re-green, and add a bit of acid if that’s not working. Worst case is that you may have to wait a few more minutes per etch with a sub-optimal bath. This isn’t rocket surgery.

5) I do have an aquarium pump ($6 at fish store) that I’ve used to re-activate my solution. Sometimes I’d leave it on for a few hours while I’m at work if I’ve been etching a lot. But lately I’ve been lazy/impatient and tossed in a couple capfuls of peroxide. Both seem to work just fine.

6) The environmental benefit of etching with copper over ferric lies mostly in not having to dispose of the copper that comes off your boards every few times you etch. When and if you do end up with too much copper etchant, please treat it like the hazardous waste that it is — look into your local hazardous chemical disposal options. There’s no getting around the fact that copper salts are (for instance) poisonous to fish even in very dilute concentrations. 

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When I originally started trying to make Cupric Chloride etchant, I hadn’t thought of just using the regular procedure of etching to get there. So I deliberately dissolved a bunch of copper from a wire.   

I don’t think it’s a particularly good idea, but here’s how I got to the end-stage etchant faster.

I mixed the acid/peroxide 1:1 instead of 1:2. The idea was to have a bunch of acid leftover for later regeneration. I don’t think it’s a good idea, and I wouldn’t do it again. 1:2 is probably better, and results in more copper in solution faster with less fuming.

To control the fumes, I used the patent-pending (just kidding) Two-Pint-Glass Fume-Containment-Apparatus. Pour in the peroxide, add the copper, then put one glass on top of the other. Pour the acid down through a small gap between the two glasses and re-seal. Voila. No fumes. (See video. I think I did it with water as an example.)

I also kick-started the formation of cupric chloride by first making copper oxide, which turns to cupric chloride just in the presence of acid alone. This isn’t necessary at all, but it was fun. Heat up a coil of copper wire on the stove to red-hot and you get a flakey coating of copper oxide. 

Otherwise, it’s basically the previous procedure, so just see the pics for notes. I wouldn’t recommend it anyway. The less copper you dissolve, the less copper needs to be (eventually?) disposed of, and the acid/peroxide etchant is plenty easy to use. 

The two-cup technique is cute. I still recommend it. 

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quick etchant 00073.avi7 MB

Finishing touches

A few drops of thinner (nail polish remover works well) on a pinch of cotton wool will remove completely the toner, bringing back the copper surface. Rinse carefully and dry with a clean cloth or kitchen paper.
Trim to final size and refine edges with sandpaper.

You will like it

The best thing about this method is that it makes possible to start with a great idea at 11:00 pm and have your prototype working by midnight. It is so straightforward that you will use it more often than you think. 
The second great thing is that this method is good enough for larger SMT parts. Actually, once you get some practice soldering, SMT parts are easier to work/experiment with, and don’t require drilling the holes.

So far, results are comparable with what I was used to get with UV sensitive boards. The board in this tutorial had 20 mils wide tracks: the word “PCTHERM” is 40 mils high and made from 10 mils tracks, and the three pads in the middle are spaced only10 mils apart.
I don’t know how the method scales to large board sizes, as I make only small boards.

A frequent question is how to make double-sided PCBs. I don’t find practical ironing two sides at once, as it is difficult to get consistent temperature. Dal Wheeler uses a document laminator for the purpose, and has put together an excellent tutorial.

So, why not give it a try? I’m sure you will like it. If you want to try it with the same circuit I used for this tutorial, continue reading about my PC thermometer!