DIY solder stencils from soda cans


Even if you’ve overcome your fear diddling about with tiny SMD components, applying solder paste – especially if you’re populating more than one board at a time – is still a chore. The pros use very expensive laser cut stainless steel solder paste stencils, something still a bit out of reach to the casual hobbyist. [Felix] solved this problem by making his own solder paste stencils very cheaply using empty soda cans.

The process begins just like any other home etching tutorial by lightly sanding the un-bent aluminum can and applying the etch resist via the toner transfer method. Etching is done with off-the-shelf HCl and hydrogen peroxide, resulting in an amazingly clean stencil comparable in quality with a professional stencil.

Sure, going through a dozen-step process to make a solder paste stencil may not be as convienent as [Cnlohr]’s toothpick and tweezers method, but [Felix]’ method is just about up to par with extraordinarily expensive laser cut stainless steel stencils. Not bad for something that came from the recycling bin.

29 thoughts on “DIY solder stencils from soda cans

  1. For a single board, or even a few boards, why go through all the trouble of reflow soldering ? You can solder these simple boards quicker by hand using a regular iron than going through all the effort of flattening soda cans, making a stencil and reflow soldering, or messing with toothpicks for that matter. For hand soldering, you don’t even need a fancy iron. Good quality solder wire, optionally a flux pen, and some solder braid to fix bridges is all you need.

    For larger runs (dozen or more boards), there’s no reason not to use laser cut stencils.

      1. If you can reach the pads from the sides, you can still do them by hand. The thermal pad can be done from the bottom if you put a hole in the right place. I’ve also seen people do the one VQFN part with paste and hot air, and the rest by hand.

    1. Hand-soldering can create problems with thermal stress, especially with surface-mount ceramic capacitors. On two occasions recently I’ve had a problem in a board which I hand-soldered and traced it to a faulty chip capacitor. One went open-circuit, the other went intermittently short-circuit at about 100 ohms. Preheating the board may help this, or using one of these special soldering iron tips which can heat both ends of the package simultaneously.

      TBH, if you have a hotplate, reflow soldering is super easy. You don’t even need solder paste – I just tin each pad a little first, then reflow with more flux.

      I wonder if it might be possible to run the thin metal directly through a laser printer, like those wedding cards were done recently (copper-clad Kapton film)?

        1. Inkjets print with Ink. Most ink doesn’t work as etch-resist it just washes off in the acid bath. Some people have had some luck with certain yellow inks but my understanding is that it is still trickier than laser toner. (haven’t actually tried it) Laser toner is a form of plastic. When you use laser toner for this you are actually coating the metal with a thin film of plastic. That’s why it works well as an etch-resist.

          1. @Zee
            SOME yellow photo inks work. From what I have read, usually name brand HP inks. It is dependant on the etchant, though, as some etchants will disolve the ink, especially if the etchant has a compound in it that is similar to the compound that was disolving the ink.

      1. I’ve been trying to run the metal through a laser printer today. In short: it will never work. The toner doesn’t stick to the metal because it can’t hold the electrostatic charge. There is no way to fix this so we must look at other printing technologies.

    1. I get mine from $80 for a single-component stencil or $125 for a full board. They also do mylar ones for cheaper but the stainless steel works better.

  2. Very clever hack, and I think it holds room for improvement. He documented his trials well, which is always a good thing to do.

    I found this experiment quite interesting: “printing to vinyl (self adhesive shelf vinyl cover) and transfer on non-sanded can aluminum interior (leaving the interior coating intact). This gave the best toner transfer, almost perfect. The catch is that you will need to scratch every pad with a needle to allow the acid to get to the aluminum. Again, can get tedious if you have many pads or fine pitch stuff. A microscope or desk magnifier makes this job easier. This also seemed to give me the almost perfect stencil”.

    A soda can is already coated pretty well. so what if you can find a clever way to selectively remove that coating?

  3. I wish I could +1 posts. This is something I may want to try in the future. I tried something like this before, but couldn’t get the etch even enough. I couldn’t keep it from etching clean through from the back in one place but not being done etching in the other. This process is definitely more fleshed out.

  4. Forget SMD soldering, this would be great for making re-balling stencils. Shedding tears of anger as my tiny BGA balls merge in the pool of unmasked flux would be a thing of the past.

  5. What is it with Hackaday and SMD soldering? Every time someone manages to do anything with SMD components hackaday remembers to tell how difficult it is, and how you need all kinds of funny way to cope with them. Yes, soldering masks are handy if you are doing a couple of dozen boards, but really, just get a decent soldering iron and pretty much anything but BGAs are easy.

      1. Placing small components by hand takes about the same fine motor skills as soldering. If anything, using an iron is more forgiving. If you shake too much placing components in the paste, the paste gets smeared. When soldering with an iron, you hold the part down with tweezers, and adjust until happy. When it’s in the right place, press it down, and use the part to stabilize the tip of the iron. For TQFP devices as in the article, use a piece of antistatic tape to hold down the device. Don’t try to solder the pins individually, just drag the tip along the pins, and fix bridged pins with solder wick.

        1. I find myself thinking you’ve not tried this on anything with particularly high pin density. Sure I’ve dealt with 1st generation ’90s SMDs with a “macro” soldering iron, but it’s a struggle to keep the tip fine enough when the flux will erode it, and also hard to find “short” irons that don’t give you inconveniently amplified movement for every little twitch, like sticking a needle in one end of a broomstick, holding it by the other end, then trying to thread it. I’m also wondering where you’re finding desolder braid fine enough not to instantly leave about 5 pins dry, instead of touching up between them. I have seen a technique where one rolls a relatively massive blob of solder over the whole line, more akin to a miniature solder bath than iron soldering, but you still need a pretty deft touch.

  6. We use disposable mylar self stick 8X11 self laminating pages at work, be do one offs on our epilog 36EXT laser. Not sure why mylars would degrade, we have reused the self sticks. Now imma go look at something. Dang it, I think there is a better way to do it.

    However, why anyone would want to hand solder more than a stray 1206 resistor is beyond me. Paste it, place it, and reflow. I got a nice bench top drawer reflow oven for less than 200 from China. We’ve used it at work for 18 months now, works like a champ.

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