10/11/2023 0 Comments Best solder paste![]() When making PCBs (printed circuit boards), manufacturers often test the solder paste deposits using SPI (solder paste inspection). ![]() ![]() The paste's physical characteristics, like viscosity and flux levels, need to be monitored periodically by performing in-house tests. An electronics manufacturer needs experience with the printing process, specifically the paste characteristics, to avoid costly re-work on the assemblies. Often missed during inspection, a head-in-pillow (HIP) defect appears like a head resting on a pillow with a visible separation in the solder joint at the interface of the BGA sphere and reflowed paste deposit. Head-in-pillow defects, or incomplete coalescence of ball grid array (BGA) sphere and solder paste deposit, is a failure mode that has seen increased frequency since the transition to lead-free soldering. Insufficient amounts of paste result in incomplete circuits. too much solder, or the solder melts and connects too many wires (bridging), resulting in a short circuit. There are many different types of defects possible, e.g. The paste is applied to the board by jet printing, stencil printing or syringe then the components are put in place by a pick-and-place machine or by hand.Ī majority of the defects in circuit-board assembly are caused due to issues in the solder-paste printing process or due to defects in the solder paste. The sticky paste temporarily holds components in place the board is then heated, melting the paste and forming a mechanical bond as well as an electrical connection. It is also possible to solder through-hole pin in paste components by printing solder paste in and over the holes. Solder paste is used in the manufacture of printed circuit boards to connect surface mount components to pads on the board. JSTOR ( March 2017) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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