NOTE: DO NOT purchase a Cricut machine! I have been informed (by TheGreatS) that the Cricut will no longer work with Sure-Cuts-A-Lot or Make-The-Cut as ProvoCraft are not willing to play nice with their customers. I will attempt to get hold of another craft cutter and redo the tutorial.
Use a Cricut cutting machine and Sure-Cuts-A-Lot software to create usable solder paste stencils for electronic prototyping purposes.
The quality and precision of the resulting stencils is good enough to prototype 0805 and TQFP (0.8mm pitch) size electronic components.
If you need PCB layout software, I recommend the free and Open Source KiCAD EDA Suite.
This Instructable is based on a tutorial I originally posted at Solder Paste Stencils.
I would not recommend buying a Cricut just to create Solder Paste Stencils. If, however, you have a friend or relative who owns one, or find a Cricut on sale or at a Garage Sale, then buying Sure-Cuts-A-Lot software will turn a Cricut into a very useful device. Functionality will then be similar to something like a low-end vinyl/craft cutter such as the Craft Robo.
Step 1: Materials and Preparation
- Cricut machine
- Sure-Cuts-A-Lot software
- Gerber Viewer software
- Transparency Film for overhead projectors which you can buy at any office supply store
- A Windows XP/Vista computer
Your Cricut must have a specific firmware version. You can update/downgrade your firmware by downloading Cricut Desgn Studio and following the directions under Help for updating firmware. Note your firmware may already be up-to-date. See the Sure-Cuts-A-Lot FAQ for more info.
Step 2: Preparing Your PCB Layout and Determining Dimensions
It may take some trial-and-error to create decent solder paste stencils as the Cricut is not very precise. It cuts rounded edges and ignores shapes smaller than about 18mil(0.46mm) by 50mil (1.27mm). This means you should make sure all your component pads are large than this. To make sure a pad still has enough solder paste area, make the pad longer. The KiCAD EDA Suite's PCB layout program has the ability to change all of a footprint's pads at once. Solder has this amazing property that during reflow it 'finds' metal pieces to link. As long as your PCB has precise solder resist, solder will find metal pieces to link. So don't worry about making pads too large (within reason, say +/- 20%).
You need accurate dimensions of your PCB stencil for later. Use your PCB layout software's distance tool to determine the distance between the outermost component pads. Not the size of the PCB, but the distance between outermost pad edges. In the example below, the PCB has a width of 2.3" but the edge to edge pad distance is 2.142".
In KiCAD, you can measure distances by selecting Drawings from the Layer pull-down menu and clicking the Dimensions button in the right-hand tool menu. It is the 4th button from the bottom.
Step 3: Creating Gerber Files
Plot your PCB layout's Solder Paste stencil Gerber.
If using KiCAD, select Plot from the File menu. In the Plot Window, select SoldP_Cmp for Solder Paste Component Layer and click the Plot button.
Step 4: Open Gerber File for Conversion
Open your Gerber file in Gerber Viewer. Select Open Layer(s) from the File menu.
Step 5: Export Gerber File to SVG
Then export the file in SVG format. Select Export, then SVG... from the File menu.
Step 6: Cutting Software
Import the SVG file into Sure-Cuts-A-Lot by Selecting Import SVG... from the File menu.
Step 7: Resize the Design
Click Keep Proportions in the Properties Window and set the stencil's width to the value you noted earlier.
Step 8: Prepare Transparency and Machine
Take a sheet of transparency film and cut it to the size of the Cricut's cutting mat. Tack the cut transparency to the cutting mat. Insert the cutting mat into the machine and press the Load Paper button.
Set the Cricut's Pressure wheel to High, the Speed wheel to High or Medium, and the cutting blade depth to 5 or 6. Detailed instructions can be found in the Cricut's manual. Some trial-and-error is required here. Speed and pressure may change the precision of the cuts, and larger cutting blade depth speeds up how quickly you will need to replace the cutting mat.
Step 9: Cut Your Stencil
Proceed to cut the design. Select Cut Design from the Cutter menu.