Screen Printing is a Science, not an Art Available to Purchase

In a production environment, the first process applied to a bare printed circuit board is generally the application of solder paste. It has been reported that 60% of all rework is attributable to poor quality solder paste deposition. If this process is not understood or the incorrect selection of paste, screen/stencil or squeegee is used, then regardless of technical capabilities of the printer, it will not be possible to achieve accurate and repeatable quality of work. This paper reports on the basics of solder paste deposition with mathematical formulas and diagrams to support the correct selection of criteria. Most importantly, it is intended to assist in the selection process and provide an understanding of the reasons for selecting a specific solder/stencil/squeegee to be used in conjunction with the printer. Written and compiled from a production (real world) view‐point, this paper recognises that it is certainly possible to use a non‐standard process parameter, and still achieve ultra‐fine pitch print capability in laboratory or small batch scenario. But primarily this paper is a guidance and recommendation to achieve excellent results,with as large a process window as is possible for production purposes.