How I Made My Own PCB Solder Paste Stencils at Our Fab Lab

Creating a solder paste stencil is a crucial step in surface-mount device (SMD) PCB assembly. In resource-constrained environments like FabLabs or maker spaces, traditional stainless steel stencils may not always be affordable or readily available. This documentation explores alternative stencil-making techniques using readily accessible and low-cost materials available in most FabLabs. The goal is to test various materials and methods for their suitability in producing effective PCB stencils that can be used for accurate solder paste application.

🔍What is a PCB Stencil?

A PCB stencil is a thin sheet with precision-cut openings that align with the surface-mount pads on a printed circuit board (PCB). The stencil is used to apply solder paste uniformly to the pads before placing surface-mount components. This ensures consistent solder volume and reliable connections during reflow soldering.

⚙️ Why Use a Stencil for SMT Assembly?

Manual solder paste application can be messy and inaccurate, especially for fine-pitch components like QFPs or small passives (0603, 0402). A stencil enables:

• Faster solder paste application
• Accurate and repeatable results
• Minimal solder bridges or misalignment
• Support for assembling small-batch or prototype SMD boards

Methode 1: Stencil out of Masking tape with a CO2 Laser Cutter

Masking tapes are very common in makerspaces and Fablab’s and it’s very cheap as well. I’ve seen online that people are using it with a laser cutting machine to make the stencil in a lab or space. and use for their PCBs. But there are some issues with this process in terms of reliability, accuracy, etc.. I thought of trying it out just to see how it's reflecting the results in a fablab

Every fablab has a laser cutting machine

Here is one tutorial about setting up a cheap laser cutting machine for making a stencil out of Masking tape

Image credits:- https://www.instructables.com/DIY-PCB-Stencil-Machine/

For this documentation, I’m using the Quentorres board and its design files. Quentorres was designed for the fab community to have an RP2040-based all-in-one programmer + a beginner development board

Image credits:- https://academany.fabcloud.io/fabacademy/2024/bootcamp-instructors/quentorres/

Generating the design file for stencil

Normally, the layer of SMD pads is also created while we design PCBs in ECADs like KiCad or Fusion 360, and it will be there in the Gerber files of the PCB. First step to convert the Gerber files to a vector file to cut it with a laser. The Quentorres repository already provided the Gerber files, which we sent to the PCB house to make the PCB as part of Fabacademy 2024: Doc. I’ve loaded the Gerber files in the gerber2png converter to play with layers and export the PNG file. Gerber to png don't have an SVG export as of now. So I thought of loading the file into Inkscape

I’ve turned off all the layers except the pads of the top layer, then clicked the top canvas view in B/W, then generated the PNG to download

Output file:- png

Then I’ve loaded the PNG file into Inkscape and traced the bitmap to get the outlines of the pads, then prepared the files for the laser cutting by making all the pads’ stroke 0.1 mm and no fill, and deleted the outline.

Then I’ve taken a piece of 2” masking tape, which is enough to cover the Quentorus board, and stuck onto an Acrylic piece (6 mm I think, it doesn't really matter), then placed it on our lab’s Laser machine, Trotec Speedy400.

See the results below in the images

From my observation, I think I’ve got clearly all the SMD pads I wanted except for the smallest 1.27 mm 10-pin connector. The surface is so thin and flexible in between the connector’s pads, that’s the reason it came out badly.

I’ve managed to place the tape over the PCB by aligning the pads with the laser-cut holes. One good thing about the tape, once it's placed, it won't move while applying the solder paste.

I’ve simply used a plastic squeeze tool to apply the solder paste over it. I’ve noticed that the paste is sticky all around the tape because the masking tape’s surface is so rough and papery, which is good enough to absorb the paste, so this method will consume more Solder paste than the traditional SS stencil.

Here is the result after pealing of the Masking tape stencil, feels like ok for larger pad components. You can see some pads don't have full solder paste may be I applied too fast.

After peeling, the Masking tape stencil is unusable because it's torn apart.

Methode 2: Stencil out of Vinyl Sheet’s Release paper with a CO2 Laser Cutter

for the Solder paste sticky problem on the masking tape stencil. I need to find a material that is more smoother

Much better than the Masking tape, with good quality vinyl’s release paper can work better, I think

. Here is the output of PCB stencil making with the laser cutting method, not so bad1 Right? But there are still some problem, you can see the small 1.27 mm pitch connector’s pad didn't come out really well, and some of them are broken as well because the material is not stiff enough.

We found this method 3 years ago during a FabAcademy assignment for assembling prototyping PCBs, and it can withstand up to 10-20 PCBs before the stencil starts to break. The 1206, 0805 packages with 2.54 mm pitch components work well with this method

Methode 3: With a Vinyl cutter and a synthetic sheet

Synthetic sheet is something we accidentally discovered through one of our Fabacademy student projects, when we didn't know the material existed in our local market for 60-80 rupees till the student brought it to the lab for her final project. The material is so smooth on the surface and stronger to withstand a tear unless it is cut by a knife edge.

This sheet is a kind of plastic mix, which means it can be shrunk and burned when exposed to fire, but this can be cut through using a Vinyl cutter.

Instead of lasering the PCB stencil pattern on the synthetic sheet, I’ve used our lab’s Roland Vinyl cutter with the help of a vinyl sheet placed underneath the material (a sticky cutting mat will be a better choice)

Here is how it came out in the result. This experiment was repeated on another vinyl cutter ( Silhouette Cameo 4), which came out even better. still getting the smaller pitch pads remains a challenge.

But despite the strength of the material and smooth surface finish, this is a good method that we have been using last 2 years, which helped us to manage to prototype several PCB’s even up to 20-35 Pcs, and the stencil still remains the same without tearing.

Methode 4: Using xTools F1 Ultra

xTool F1 Ultra

One of the most amazing machines that we acquired in our Super Fablab recently. It's a very smart fiber/diode laser engraver, which means it can engrave metals too. We have been using it to engrave printed circuit boards in the lab, results are amazing.

Since it engrave metals and also there are example which shows the using of the machine to emboss coins, Since it has so much power enough to emboss metal, I had to do the experiment dose it cuts thin sheets of metal as well. I’ve picked the Aluminum soda can, yes, RedBull can, to get the thin sheet of aluminum as quick as possible.

Let's grab a redbull and start thinking. To make the stencil better,

There are a lot of diy experiments and videos available to make a can into an aluminum sheet, not so hard, but be aware of safety by avoiding cutting your skin with its sharp edge.

Just required a Slide knife to cut off both sides of the can first

Then I used a normal scissors to cut off the center part into a sheet and the remaining edges to make it cleaner.

Next, I wanted to make the sheet straightening-like by removing its folding tendency.

I’ve tried to heat up the sheet to deform it, then I tried with an Acrylic scale as a squeeze tool to squeeze the sheet

And those techniques worked for me well enough; you can see them in the video

Here are some examples of how to turn aluminum cans into sheets

https://youtu.be/2-qXKC914gM

Software setup: xTool Creative studio

I’ve imported the same PNG file prepared before, directly to the Creative studio. Need to do some steps here to prepare the cutting file. Click the doc link below to see the preparation steps

👉How to prepare the cutting file for Xtools

. Here is the final setup. I’ve deleted the border of the PCB and edited the cutting setting, which I tuned for this by experimenting on another piece of aluminum can.

Settings:-

• Operation: Cut
• Laser type: Fiber IR
• Power: 100%
• Speed(mm/s): 600
• Pass: 10

I’ve sent the operation to the machine, it's only gonna take under 15 seconds as estimated in the software, Pretty cool uha!!

Material Setup

I’ve placed the sheet I‘ve prepared by previous steps, which is not quite flat on the laser’s bed, so I have to use some weight on top of the sheet

The above video demonstrates the issue with the prepared aluminum sheet, which is not staying flat, and also shows how I balanced it with weight.

Let's hit the button to cut!!

wow!! That was quick, and it was all done under just 20 seconds. The videos also show the part where the metal bends itself while cutting, it's happening because of the heat on the surface by the Fiber laser.

here is how the final results turns up, A nice PCB stencil on a Aluminum sheet made out of a simple soda can!!

Applying the Solder paste using the Stencil

I've prepared a setup using the extra PCBs I've and left a space just enough to fit the Quentorres PCB.

I can just slide the PCB in the gap to constrain the PCB on each side.

Now I've to fix the aluminium PCB stencil on top.

Alignment on top of the pads is very important, while fixing the PCB stencil on top

Here is the final setup. I've used a simple plastic squeezer to apply the solder paste over the PCB

It has to be apply from bottom to top or need put pressure on the stencil and PCB to make sure it's not moving.

Here is how it's come up. Pretty neat!!, Now I need to place the components on the board

I’ve carefully placed all the necessary components by hand and with a tweezer according to the BOM of the Quentorres board as says in the documentation.

Now the board is already for the oven to cook and solder everything in place. You may also have noticed that I didn't place the 2x5 10 POS connector in the board, which I avoided purposefully, I just don't like it

Before I proceed with the final step of the soldering, I thought of pushing the limits of the F1 Ultra to see how small it can go or how small holes it can cut through for a PCB stencil on an aluminum can sheet

🤔 Can the F1 ultra cut small pads on the Aluminum can?

As I’m curious about this process, I thought of picking the type C breakout board, which we use widely in our lab’s PCB prototype, for adding type C access in electronics. I designed a PCB breakout board 2 years ago. Find the documentation here,

The picture shows that the results of the stencil I’ve made for the type C breakout board came out well, needed a small pin assist to remove some of the cut part, to clear the holes,

and here is how I used it for applying the solder paste, the picture shows the PCB slightly moved while the squeezing process which is resulted an offset in one direction, but the solder paste on individual pads came out very well.

after placing the components, I’ve showed the PCB under a hot air station for the reflow process, which came out so good!!

After I show to the Fabacademy2025 community what I did with the Soda can aluminum sheet and xtool’s F1 Ultra, Prof. Neil Asked me to try a smaller foot print components, to check is it possible cut that small foot print using F1 Ultra, He suggests me to try with a 6-axis small IMU sensor called LSM6DSV16X ( Neil explain more about the sensor uses in input device’s fabacademy classes)

How Small can it go??

Let's begin, I got the footprint library from the snapEDA website and loaded it to Kicad and exported PNG through gerber2png workflow mentioned earlier in this documentation

. Footprint source: https://www.snapeda.com/parts/LSM6DSV16XTR/STMicroelectronics/view-part/?ref=search&t=LSM6DSV16XTR&ab_test_case=a

. Here is how the 6-axis LSM6DSV16X IMU sensor unit’s pads came out on the aluminum sheet. seems it burns and melts the borders of the hole because it is so small and close each other. As Neil say, we can improve the quality of the result with a bit of sanding on the surface of the aluminum sheet, and maybe adjusting some parameters in the xTool’s studio settings too. But overall this was not a bad try, and the results are looks good.

🔚 Co nclusion

This whole thing started as a small experiment — I just wanted to find a simple way to make good-quality PCB solder paste stencils using the tools we already have in our Fab Labs and makerspaces. After trying out different methods and machines, the Xtool F1 Ultra turned out to be a game-changer — fast, clean, and super precise for cutting stencils.

Oh, and you might be wondering about the soldering process of the Quentorres board. While I was doing all these stencil-making tests, a thought hit me — what if the same laser could solder the components too?

That question kicked off another round of experiments, and the results were pretty exciting. I’ve shared all of that here:👉 Laser Soldering PCBs with Xtool F1 Ultra — A New Maker Hack

This Hackster post is actually a split version of my full documentation. If you’d like to see the entire journey — from stencil making to laser soldering — you can check out my original detailed write-up here:📖 Stencil Making and Laser Soldering — Full Story on Notion

~ Happy Making🙌