Introduction: How an SMT Stencil Is Made
While through-hole components began as the norm in the electronics industry, the invention of SMT parts lead to their eventual replacement. SMTs allowed for much faster PCB manufacturing than ever before by allowing a layer of solder paste to be placed on all the lands of the board at once and to have all the components be reflowed at once. In the modern electronics industry, a basic knowledge of how SMT stencils are made is very helpful in determining the right stencil for your project.
Step 1: Overview
While there are many ways to make solder paste stencils, both for industrial and hobbyist purposes, one of the most common ways is to use laser cutting. In this method, a computer controlled, high-precision laser is used to cut the apertures in the stencil according to a design given by a CAD or GERBER file. High quality lasers can allow for spacing as tight as 0.15mm between apertures in the solder paste stencils.
While they all share the same cutting methods, there are three main styles of solder paste stencil that are commonly offered. They are: metal stencils, StickNPeel, and StencilMate.
Step 2: Metal Stencils
Metal stencils are the traditional option when it comes to applying solder paste. Holes cut in a sheet of metal, called “apertures” allow solder paste to be applied to the PCB. Reliable and reusable, metal stencils are available in framed, unframed, and prototype styles. For a more in-depth guide on the different types of metal stencils and the benefits and drawbacks they provide, you can also look on soldertools.net for SMT stencils
Step 3: StickNPeel™ and StencilMate™
The StikNPeel ™ and StencilMate ™ are other solder paste stencil options designed with the goal of streamlining the rework and repair process. They are both fast and disposable stencils that look to simplify the rework process. These metal stencils use adhesives to adhere to a specific part of the board, allowing for easier selective application of solder when it is necessary during rework. Rather than use a stencil to resolder the whole board, manually resolder parts, or simply scrap the board altogether, these stencils save both time and cost by allowing components to be selectively repaired or replaced.