Hello friends !! Making Prototype for electronic circuit has always been a very messy job, specially when you have to deal with SMD components involved in your design. But Very thanks to Lion Circuits
The Lion Circuits made it very easy to have a online platform for PCB prototype making at very cheap rate. It provide you the furnished PCB and Stencil so that you can easily convert your design into a real hardware.Generally stencils are of steel plate but they cost u alot. For prototype purpose plastic stencil is a better choice.
In this tutorial I will show you step by step, how to generate a gerber file to order a stencil online from Lion Circuits and how to use a Plastic stencil to apply solder paste to your PCB board.
Let start without further delay ... ;)
Step 1: Generate Gerber File With Eagle Software to Order a Stencil Online Form Lion CIrcuits
I assume that you have your design ready in eagle. Follow these steps to generate the gerber for stencil form this design Download the CAM file provided by the Lion Circuits, you will need this in steps below. Refer the images shown
1. Select layer settings Menu form left side icons
2. In layer settings select none and then select tCream from layers. You will see, how your stencil is going to look like. (these two steps are only to have a idea how the stencil is going to look like)
3. Select the CAM Processor Icon from top icon bar. Select File->Open->Job. Browse the CAM file you have downloaded previously (Lion_Circuits.cam)
4. Now click on ADD menu in the bottom and Name it Stencil. Change file extension to .STN. In right side deselect all the layers and select only tCream layer.
5. Click on Process Section Menu. Now a file has been generated to your eagle project folder with a extension .STN.
6. Send this file to Lion Circuits for quotations and other enquiry.
Step 2: Making a Arrangement for PCB and Stencil
Now when you get your plastic stencil. Make a arrangement like shown in images before you start apply solder paste.You can use bare PCB's and wire tape to do this. By using this kind of arrangement you can use it a number of time to apply solder paste to PCB's.Now align the plastic stencil over the PCB so that the blank spaces of stencil are perfectly above the SMD pads.
Step 3: Applying Solder Paste Using Plastic Stencil
Now when you fixed the stencil and PCB use a syringe with solder paste in it to apply on blank spaces of stencil. Use a blonde edge blade (Use carefully it can cut the plastic stencil if not properly used ) to make it uniform and remove extra solder paste. Lift the stencil slowly. That's It ... :)
Step 4: Placing Componets
Place all the components. Don't worry if there is some misalignment during component placement. It will automatically be at its place once you heat it up
Step 5: Heating PCB With Heat Gun
Now Heat the PCB at 280 degree using a heat gun for one minute you can visually see the solder paste turning into solid and components getting aligned during heating.
Step 6: Benifits of Using Plastic Stencil
Plastic stencil is very cheap compare to steal stencil. You can use these stencils if you are running a small production unit. Have a happy and successful prototyping... :)