Prototyping tutorial: Quick and dirty solder paste stencils

PCBs made with a DIY stencil

Solder stencils are pretty cheap these days, but for a single, quick production run of a really simple design, it seems like a waste of resources to have a professional one produced and shipped to the lab. Of course, if you have a laser cutter handy, you can make a pretty nice one, but if all you’ve got is a rusty knife and some office supplies– don’t fret! You are still in luck.

I’m actually pretty stubborn, and until recently I would just solder this kind of job by hand. This time, though, my good friend Honghong was around to set me straight- she explained a totally cheap and dirty procedure that they use at her factory to make stencils quickly. We tried it out here, and are happy to report that it works great!

It It turns out that soldering stencils aren’t really anything special, at least for large components- they’re basically just pieces of thin material with holes cut in them. In fact, you probably have all the material you need to make one right now- a piece of transparency sheet or velum, a knife, and some tape. So without further ado, the instructions!

Step 0: Gather materials

You will need:

  • 1 sheet of velum, preferably 2-3x the size of your PCB
  • 1 sacrificial PCB for the template
  • Masking tape
  • Xacto knife (the sharper the better)

Step 1: Tape the velum to the PCB

Tape velum to the PCB

Use masking tape to secure the PCB to the velum. The top side of the PCB should point towards the velum.

Step 2: Cut holes in the velum

Cut the mask

Use the X-acto knife to cut out openings over the SMT pads on the circuit board. I cut out little rectangles. If you have a small drill handy, you could also just drill holes here.

Step 3: Check the hole alignment

Inspect the PCB mask

Once you have the holes all cut out, double check that the holes line up with the SMT pads, and that there aren’t any rips or tears in the paper. I messed up the first one, but after replacing the blade on the knife, the second one was fine.

Note that I intentionally left out the big component in center of the board- that one is an LED that would be damaged by this reflow process. Those will be soldered on by hand later.

Step 4: Make a simple jig to hold the PCB in place

Make a temporary jig

This is optional, but will help speed up the assembly process. Tape some old PCBs to a thick sheet of paper, forming a corner for your board to fit into.

Step 5: Align the solder stencil, and apply the paste!

Apply solder paste

Place the solder stencil over the board, and align it to the correct position on the board. Next, apply solder paste using a squeegee tool. Carefully peel back the stencil and remove the PCB.

Step 6: Inspect

Inspect the finished PCB

If all went well, you should now have a PCB with solder paste on it! Add components using your favorite method (tweezers, vaccuum pen), and reflow the board.

Conclusion

This is a truly quick and dirty method for making solder masks, and is nice because it only requires a few hand tools. It’s great for situations when you want to test a new design or make a single, small run of boards, but don’t want to waste time and money on a professional stencil. Share how your build works in the comments!

7 comments

  1. Margaret says:

    Great article. Thanks. I haven’t used a stencil before – just received one from Osh Stencils now waiting on my PCBs from OshPark – excited! This looks like a good method to try. I’ll probably give it a go for my next rev of the PCB. I appreciate this info. I learned something.

  2. matseng says:

    Is that castellations at the edges of the pcbs? With plating of the barrels of the half-holes? Since there’s a serial number on the pcb it looks like it’s produced at one of the cheap places like itead or seeed but I don’t think they support castellations. Where did you do yours?

  3. HONGHONG says:

    For the velum, I prefer to use PET velum. If you are in China, you can try to search “喷墨制版打印胶片” and buy it on taobao. In fact I am a little lazy, I would like to use 1.0mm~1.5mm drill for the 0603 SMD components.

  4. Hi Matt ! Nice blog you have shared. I know that StikNPeel™ rework stencil is one of those products that simplifies the rework of site locations by placing a highly flexible, removable, adhesive-backed stencil on to a circuit board for localized solder paste, adhesive or flux printing. Your blog is very informative thanks for sharing.

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