Step SMT Stencils
There are often a wide range of component sizes on an electronic assembly.. The goal is that no matter how complex the assembly, that solder paste is delivered at the correct volumes to all components. There are a number of ways in which to achieve correct paste volumes, one of these being the step stencil.
What is a step stencil?
A step smt stencil is a standard stencil where a portion of the metal over certain components is either made thinner (step down) or thicker (step up) to accommodate a needed change in paste volume.
When do I need a step stencil?
Typically a step smt stencil is considered after other avenues have been fully explored like overall stencil thickness change along with aperture design changes. You may consider hand soldering the component in question which is feasible for a quick prototype but is not for a production run. If these alternatives cannot provide you with the desired result then a step stencil may be the option for you.
When to step up or down.
This arises when you have a mixed technology assembly. You end up in a situation where most of the assembly is of similar design and you have one or two location that require a vast difference of solder volume to achieve the correct solder joint. By changing the thickness of a certain part of your stencil, it allows paste to be added at the correct volume needed for that component. The application will either be a step up which means that most of the assembly requires a smaller volume of paste to achieve the correct solder joint and you have a component that requires a much larger paste volume to achieve the proper solder joint. A step down stencil is just a reverse of this.
How it’s done.
Adding a step to an stencil is a relatively easy process. A step up is achieved by either micro welding a piece of metal on top of your smt stencil or back etching the entire smt stencil except the step up location to create the correct thickness at that component location.. A step down is achieved by either laser etching or chemical etching the correct location to the desired thickness.
If you feel that a step smt stencil may be the right fit for your project then feel free to contact our helpful engineers with your questions! Call us toll free at (877) 697-8362 or email Info@i-source.net.
