Screen Print and Reflow SMT Boards at Home

I'll take you through all the steps using a new prototype stencil tool developed specifically for your home shop and (don't laugh), a common toaster oven. Face it, building SMT boards at home will never be a 'piece of cake', but this new procedure should help make it a lot easier and maybe save a little time and money by keeping more of your project in-house. Here's what I'll be working with:

These products and materials are available from PCBexpress (www.pcbexpress.com), a vendor that I use to build my PCBs. Regardless of what vendor you select, all tools in home stencil kits would basically work in the same way. There are only so many low cost ways to screen print at home - and, a toaster oven is a toaster oven. Most sources have at least two levels of kits available. What you want depends on how "single source" you like to be. Of course, all kits offer complete "How-To" instructions.

Ordering your PCB and Prototype stencil

First, you need to get your prototype stencil made. Although they're not just for prototype products, I like to call these stencils "prototype" to differentiate them from standard framed production stencils. These "frameless" type of stencils run from 50% to almost 85% less than the cost of conventional stencils.

You can have both your board and stencil made by a single vendor as I did or, if you already have your boards, there are vendors that will just make stencils. In the past, I've purchased prototype stencils for existing boards from Stencils Unlimited on the internet (www.stencilsunlimited.com) and I'm sure there are others you can find with a simple web search.

A Basic Prototype stencil Kit comes with: Prototype stencil Squeegee Blade PCB Holders

A Starter Prototype stencil Kit also has: Solder Paste Reflow Temperature Indicator

To order a stencil, you need to send the vendor your Gerber files just as you always do to get your design made up, but in a little different way if possible. When you send in your board design, indicate both the silk screen and solder paste layer in your Gerber files. The PCB or service will take those files and create the prototype stencil pattern from them.

Some of you may not have a software program that can create the silk screen and stencil layer files. In this case, the vendor can use the top and bottom copper Gerber files and edit them to create the pad openings in the prototype stencil that match your board design. It's a little more involved, but a common practice - even in professional run production. The big electronic contract shops run into this all the time, so don't fret if you don't have the capability to create these special files. Any good PCB or frameless stencil vendor does.

Choosing Your "Reflow" Oven

The only part of this project that you can't get from any PCB vendor that I know of, is the "reflow oven". The following toaster ovens have been tested and were found to meet the reflow requirements for most SMT PCBs 9 X 11 inches or smaller. I can't guarantee the results you may get using any other models. This is a good size selection and you can find most models well under $100 at any local discount store.

GE OVEN WITH SOLDER PROFILE

BLACK & DECKER TRO 5900TC WITH SOLDER PROFILE

OSTER 6230 & 6232 WITH SOLDER PROFILE