NPL releases stencil and aperture design report

NPL has announced the release of a new report on the influence that stencil and aperture design has on fine pitch printing using various solder paste types. The report explored the limits of printing at fine pitch for three different sized solder pastes. This investigation encompassed using stencils manufactured via different routes and explored the difference in paste release between round and square apertures. Paste release from the stencil walls becomes key with small apertures and the ratio of opening to aperture wall appears to be a good guide to printability. From a printing point of view thin stencils and Type 6 solder pastes will yield the highest performance, but this will need to be taken in the context of other factors in the assembly process. Stencil characteristics that provide the best performance are electroformed and with round apertures. Source: PCBnewsline