Product category:
Electronics Manufacturing Materials and Consumables
News Release from: Tecan | Subject: PRA stencils
Edited by the Electronicstalk Editorial
Team on 03 March 2004
Novel stencil pattern encourages paste
roll
Subtle stencil design enhancements from specialist manufacturer Tecan actively promote better aperture filling and printed deposit definition, leading to improved consistency across the printing proce
Subtle stencil design enhancements from specialist manufacturer Tecan actively promote better aperture filling and printed deposit definition, leading to improved consistency across the printing process Ongoing development and optimisation has led to the implementation of a proprietary technique known as paste roll activation (PRA) across the company's range of enhanced stencils, including electroformed, precision laser and laser-formed variants
This article was originally published on Electronicstalk on 24 Oct 2000 at 8.00am (UK)
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PRA is effectively a microfine pattern created on the squeegee side of the stencil which has been designed to significantly improve paste roll.
The PRA wave pattern assists in activating and "conditioning" the paste to improve its rheology.
This paste conditioning also extends the printing life of the paste.
Effective paste roll is an important prerequisite for successful solder paste printing and the PRA pattern encourages paste roll within 5 to10mm of the start of the printing stroke, thereby reducing the run-on and run-off distances, which ultimately increases the print area.
The PRA pattern delivers a better aperture filling capability than non-PRA stencils and is proven to be particularly beneficial for fine pitch applications in both leaded and lead-free production.
The company recognises that optimum paste condition is critical to the printing process.
In response, it has also developed highly polished electroformed squeegee blades that help to overcome rheology problems associated with no-clean and less dense lead-free pastes.
These specialised squeegees reduce paste hang-up when the squeegee has completed the print stroke.
They are designed to optimise performance when used in conjunction with PRA stencils to ensure that apertures with even the smallest dimensions are filled appropriately.
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