We’re kind of surprised we haven’t covered this concept before since it only uses techniques that are commonly avaialable for home PCB fabrication. [Ray] made this solder paste stencil out of a sheet of copper using the same etching techniques you would for a circuit board. He designed and printed a resist pattern, with toner everywhere except the places where there should be holes in the stencil. He transferred the toner to the copper using an iron.

The difference here should be obvious; this a thin copper sheet with no substrate. Because of that, you must protect the copper surface before etching. he covered the entire thing, both sides, in packing tape. After that it’s into the Cupric Chloride bath to dissolve the exposed parts. Once the tape and toner has been removed you can scree a precise amount of solder paste onto your boards.

This isn’t for everyone, but if you’re assembling many boards it’s not a bad approach. If the stencil is no longer used it can be recycled, but we do wonder how corrosion on the copper will affect the stencil’s performance.

The idea for this technique came to [Ray] from a guide that’s been around for years.

Hackaday reader [David] was looking for a cheap and easy way to spot weld copper tabs together. As he notes in his writeup, the properties of copper which are most enticing, such as high thermal capacity, make welding it all that more difficult. His home-brew method of spot welding is admittedly quick and dirty, but it does get the job done quite well.

He started off with an array of four 2.5V @ 2600 Farad ultra capacitors, which provide the high current required to do copper spot welding properly. They are wired in series and connected to his electrodes using heavy gauge wire. The graphite-tipped electrodes were an interesting DIY job themselves, cleverly constructed using copper tubing and a graphite block. The most simple/dangerous/clever part of the whole rig is his trigger mechanism, which consists of a pair of copper blocks that he bangs together manually to complete the circuit.

[David] is well aware that the setup is just a touch rough, but according to him it makes great welds, and it’s only a proof of concept at this point. He has a hefty list of improvements to make for the final version, including a different switching method among a few other safety precautions.

Here’s a DIY vaporizer build. It uses a 30 watt Radio Shack soldering iron as a heat source that is regulated with a common dimmer switch. This is done by removing the soldering tip and replacing it with threaded rod attached to a brass pipe fitting assembly. This is housed inside of a Mason jar with a copper pipe for air intake and another for output. Not surprisingly the creator tipped us off anonymously, saying that this a “smoking accessory”. A bit of searching and we came across this Wikipedia article about a Volcano Vaporizer which sheds light on what one is used for.

We don’t condone using illicit substances. But even more so, we’re skeptical about breathing through this thing because of the warning that [Anon] included about noxious vapors put off by the epoxy putty when it heats up. Still, it’s an interesting build so we though we’d share.

[Jeri Ellsworth] continues her experiments with electroluminescence, this time she’s making EL ink. The ink she’s looking for is Zinc Sulfate in a solution. The process she chose is to re-dope some glow powder so that it can be excited by the field around an AC current. In her video (embedded after the break) she talks about the chemical properties she’s after by detailing a cubic lattice of zinc and sulfur atoms with an added copper atom (adding that atom is a process called doping).

The quick and dirty synopsis of the experiment starts by washing the glow powder with dish soap to acquire zinc sulfide crystals. Then she combined copper sulfate and zinc shavings from the inside of a modern penny to yield copper metal and zinc sulfate suspended in solution. That was mixed with the zinc sulfide from the glow powder washing and doped with a little more copper sulfate. The excess liquid is poured off, the test tube is capped with glass frit, and the whole thing hits the kiln to start the reaction. The result glows when excited by alternating current, but could have been improved by adding chlorine atoms into the mix.

We’re excited every time we see one of [Jeri's] new chemistry hacks. We’d love to see more so if you’ve come across interesting chemistry experiments during your Internet travels, please let us know about them. Just make sure you have some idea of what you’re doing when working with chemicals… safety first.

Forget hacking an easy button, grab a couple of those outdated CD-Rs and build your own switch for that next project. This was developed with handicapped accessibility in mind; assembled easily with common products and it’s fairly robust. In fact, our junk box has everything you need except the adhesive backed copper foil. Combine two old CD’s, covered in copper on facing sides, separated by two strips of Velcro to separate the conductors. When pressure is applied, one CD flexes to make contact with the other and complete the circuit. So easy, yet we never thought of it. We’ll add it to our list of homebrew input devices.

[Thanks Michael]

Pulsar Professional FX has a neat tip on their site for getting a really even toner transfer when making your own PCBs. First, the PCB is cut to size, and the paper is tacked to the board. Then, the PCB is placed paper up onto a dowel and rolled back and forth with the iron. Since the board bends slightly over the dowel the toner sticks evenly to the copper. After that, just remove the paper as usual and etch with your preferred method.

Etching a printed circuit board generally takes a bit of time and uses a lot of etchant. [TechShopJim] posted a method that uses a sponge to reduce the amount of etchant used while speeding up the entire process. First, a resist is applied using either a sharpie or the toner transfer method. Using gloves to handle everything, he soaked a sponge in ferric chloride and continually wiped a copper-clad board until all the exposed copper was removed. This technique moves the etchant around more, keeping “fresh” etchant closer to the copper. If you can’t procure ferric chloride, you can also use our method that uses 2 household chemicals: hydrogen peroxide and hydrochloric acid.

[ladyada] has republished an interesting snippet from the synthDIY mailing list. [David Dixon] discusses the actual chemistry behind ferric chloride based home circuit board etching. He concludes that ferric chloride is essentially a ‘one-shot’ oxidant. It can’t be regenerated and can be difficult to dispose of properly. The use of acidified copper chloride is a much better path and becomes more effective with each use, as long as you keep it aerated and top up the acidity from time to time. This etchant solution is actually the result of initially using hydrogen peroxide as an oxidant along with muriatic acid. You can see us using this solution in our etching how-to and while creating the board for our RGB lock. For more information on using hydrogen peroxide, check out [Adam Seychell]‘s guide and this Instructable.

Aside: [ladyada] has added the receiver code to the Wattcher project page.

[nmarquardt] has put up an interesting instructable that covers building RFID tags. Most of them are constructed using adhesive copper tape on cardstock. The first version just has a cap and a low power LED to prove that the antenna is receiving power. The next iteration uses tilt switches so the tag is only active in certain orientations. The conclusion shows several different variations: different antenna lengths, conductive paint, light activated and more.

Many people use protoboard and point-to-point wire everything, but needing multiple copies of the same circuit is the reason that forces many away from using protoboard. After making your first circuit board, you might not point-to-point wire anything again!

For your first circuit board, one goal is to keep the circuit single sided so you can etch using single sided copper clad. This will allow you to gain some experience before moving on to double-sided. If you need topside traces, simply run a few jumper wires on the top. There are many complete circuit layouts you could try like the Hack a Day design challenge winner.

Here is a list of materials you will need to produce a single-sided board. With the exception of the copper clad and PCB drills, everything on this list is easily obtained at your local store.

Materials: Muratic acid, common household hydrogen peroxide, safety goggles, good quality magazine pages (cut to 8×11), laser printer, single sided 1 ounce copper clad, a plastic container the board will fit in, soft plastic brush, clothes iron, lacquer thinner, rubber gloves, paper towel, tin snips, drill or rotary tool, PCB drill bits, Scotch Brite scrubbing pad, good ventilation, 5-gallon plastic pail full of water.

Now, here is how you do it:

Print the bottom side layer on a piece of paper from a high quality magazine. Use one actual page from the magazine, the thicker and shinier the magazine paper the better, but do not use the cover. You must use a laser printer, not an inkjet. If your printer uses ink cartridges and not toner cartridges, it will not work. If you do not have a laser printer, you can work around this by printing to white paper and using a photocopier set to the darkest setting to copy the layout to the magazine paper. If the paper jams in the printer, you are not using a thick-enough magazine page. Again, do not use the magazine covers, as they do not work.

Magazine pages are used because they work well, and they are cheap! The reason they work is because the paper is very glossy and the toner does not adhere well to the glossy pages. The printing used on the magazine page is ink and it does not come off, but toner does. Toner is actually a plastic polymer, and different toners may yield varied results. In our experience, a genuine HP toner cartridge was used with great success; an Office Max brand yielded poor results. The sole purpose of the toner is the protect the copper below it from etching away, you only want the uncovered areas to etch.

Next, wash your hands to remove any oils. Keep handling to a minimum once the pages are printed and do not touch the laser printing with your fingers; this could get oils on the printing. Keep pages as flat as possible.

Very carefully, remove the copper clad from the packaging. Do not touch the copper surface for the same reason as above. You can cut the copper clad to size using a tin snip if needed. Use the Scotch Brite scrubbing pad to gently buff the surface (Scotch Brite is a popular brand of of plastic scrubbing pad meant to emulate steel wool). Do not use steel wool because it will embed steel into the copper. Clean off the residual dust with a slightly damp paper towel.

Find a hard, very flat, sturdy, heat resistant surface. Empty the water out of the clothes iron and set the iron on the hottest setting. Allow the iron to get hot.

This is both side of a piece of copper clad. Place the blank side facing down and copper side facing up. Align printing/paper onto copper clad board with the printing facing the copper. Do not allow it to move.

Firmly press the iron onto the back of the magazine paper, sandwiching it between the copper clad and the iron. Pressing hard without moving the iron, hold the iron perfectly still for one full minute. Do not move the iron at all during this minute, and push hard, really hard!

Then, for four more minutes, slowly move the iron around making sure to put a lot of pressure on the paper, but not allowing the paper to slide on the copper. When done, let the board fully cool before you move it at all. This will allow the toner to adhere to the copper and prevent you from being burned.

Put the board in cold water and let soak for five minutes. After five minutes, try to peel the wet paper from the board leaving only the toner/print from your laser printer. Only the toner should be left adhering to the copper. If the paper does not come off easily, let it soak in the water for a while longer. If necessary, rub with your finger to remove any paper, leaving only the toner. It’s ok if there are a few excess paper fibers stuck to the toner.

If you find not every trace adhered to the copper clad or it is misaligned, use lacquer thinner and paper towel to clean the toner from the copper board and start over. If the traces look good then move on. Inspect the traces carefully, however, because what you see now will be your finished product.

In a well-ventilated area with a fan, add 2-cups hydrogen peroxide to a plastic container. Gently pour in 1-cup Muriatic acid, to create the etching solution. Always wear goggles, gloves, and do not inhale the fumes. Do not use any metal containers, measuring cups, stainless steel sinks, or tools with this mixture as this mixture will aggressively etch metal. Acid safety, think “triple A”, for Always Add the Acid, it’s whatever is in the container that will end up splashing. This etching solution, while made with common chemicals, should command respect. It is dangerous to yourself and surroundings, treat it with respect. Ferric Chloride is another common etching solution, it is not a safer solution to use, both are equally dangerous.

Put the board copper side up in the plastic container filled with etching solution. Use a soft plastic brush to gently wipe the board. You will notice the copper begin to dissolve. It takes about 3-4 minutes to get all the exposed copper dissolved. You just have to watch to make sure it is gone in all areas between the traces. Do not leave the board in the etching mix for too long as the traces will dissolve under the toner that is protecting them.

Use lacquer thinner (paint thinner and acetone do not work well) and a paper towel to remove any toner left on top of the copper traces.

Tinning prevents the copper from oxidizing, which can make it hard to solder to in the future. If you choose, you can tin all the traces with solder and a soldering iron now. This actually makes drilling much easier because it helps to center the drill bit. Make sure to clean off excess flux if you do this. You could use Tinit to chemically plate the copper. Here is a different tutorial describing its use.

Drill all the holes for the through-hole parts using the correct size PCB drill bit and rotary tool. Drill large mounting holes with a normal drill. PCB drill bits are carbide and made to drill through fiber glass that would quickly dull standard bits. There are a few very common sizes of bits and these are often sold in packs. We use .0260″ for IC holes and .0310″ for resistors and caps.

Print out the top side silkscreen layer on magazine paper and iron this onto the top side, using the same processes as above. Again, run under water and peel off the paper. Now you have the component ID’s on the top side.

Here is a different video using essentially the same method:

You can make really nice PCBs of your own circuit design using this simple method, and we look forward to seeing your future projects using this method coming in on the tip line. Look for more How-Tos like this one in the How-To category.