Journal of SMT Article


Authors: Ian Fleck and Prashant Chouta
Company: Cookson Electronics
Date Published: 1/1/2003   Volume: 16-1

Abstract: Over the years stencil design has made a transition from traditional art that is based on experience to a modern day scientific approach based on designed experiments, which will deliver optimum print performance. Modern technology puts high demands on the different aspects of stencil design, which has to account for the fine pitch, as well as the large pitch components on board.

Moreover, to control paste print volume, an engineer has to choose the best performing aperture geometry, stencil thickness, aperture wall taper, and whether or not to electropolish; not to mention the varied manufacturing techniques, which in most cases dictate the stencil manufacturing costs. This lack of in-depth understanding of the subject motivated our team to investigate the issue with a test matrix comprising all the possible combinations of stencil aperture design and manufacturing processes currently used in the surface mount industry.

The variables evaluated for this study are spread across different materials and manufacturing methods; coupled with innovative aperture geometry covering a wide range of sizes. A designed set of experiments is performed to find the effect of all the identified factors on the response variables.

The resulting knowledge base consists of more than 10,000,000 records of data. The results help clear some of the widely perceived misconceptions regarding stencil design and the different manufacturing processes. These answers give a new dimension to the fundamental understanding of a stencil aperture design and its resulting effect of print performance.


stencil printing, taper, electropolish, laser-cut, chem-etch, electro-form, transfer efficiency

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