|Ask the Experts|
June 29, 2020
Step Stencil Squeegee Angle
If you have step stencil, what angle should we use for the squeegee when printing solder paste, and what other parameters are important?
|Expert Panel Responses|
We recommend using the standard 60 degree squeegee blade angle for most applications. It is beneficial to slow the print speed to give the blade more time during printing to conform around / into the step.
A general starting point for print speed would be 20-30 mm/sec. The blade pressure should be set as normal for the solder paste, e.g. use just enough pressure to clean the paste off of the stencil. It is a good idea to contact your solder paste supplier for more specific recommendations.
If using a Stainless Steel squeegee blade then a 45° angle should work. If using a polymer squeegee blade several factors are to be considered. However if using a durometer of 65 and the polymer blade is a flat edge I would start with a 35°. If the blade is a diamond cut, then a 0° to 8° should be tested.
Please note: There are unknown factors at the moment; as in solder paste mesh type, squeegee pressures, printing speeds and squeegee length, stencil thicknesses, stencil snap release speeds and distances.
Circuit Technology Center, Inc.
Angle of squeegee for stepped is exactly the same as normal, more important is not to over pressurize the squeegee blade (1Kg every 50mm of squeegee length) and don't go too fast T4 powder around 25mm/s speed.
Technical Sales Manager
BLT Circuit Services Ltd
The purpose of the step-up or step-down stencil is to achieve maximum solder deposition in the modified area. As with a regular stencil you should also consider squeegee pressure and speed.
Most of my work has been with a laser-etched stencil and a plain metal squeegee at an angle of 60 degrees. For a step-up and down stencil I've read a couple of white papers that recommend 45 degree squeegee angle and a metal squeegee that has some type of coating along its edge that will provide a better adaptability to the stencil surface.
Senior Manufacturing Engineer
I would not change the angle of the squeegees you are using now. Monitor the pressure, speed and cleanliness of the stencil after paste application.
Engineering and Operations Management
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