Traceability and Verification for the SMT printing Process

Abstract

Process traceability and verification has become increasingly important as electronics assembly has moved to higher throughputs and volume requirements with tighter process windows. Ensuring repeatable, high yields requires an optimized process that is constantly in control. Knowing and tracking every parameter relative to how a PCB has been assembled is critical to maintaining control and traceability. If and when something goes wrong, it’s a lot easier to get to the source of the problem with comprehensive traceability.

The solder paste printing process is critical, since it is estimated that more than 60% of all soldering defects originate with the printing step. Accordingly, a system has been developed to add traceability, data harvesting, and reporting to the printing process.  Named PrinTrack, this system creates an easily-accessible comprehensive history detailing how and when a PCB was printed, the process settings, materials, and options used to print it, and all pertinent information that can be used to track PCB assemblies and troubleshoot the process if needed.  

Stainless steel foil stencils are used to print solder paste and adhesives on bare PCBs. Stencils of varying thickness, and also ‘step’ stencils with varying thicknesses in specific areas for different deposition requirements are used.
Solder Paste, a complex mixture of tiny particles of solder alloy and flux vehicle, is a challenging material to print onto a bare Surface Mount Technology (SMT) PCB.
Traditional metal screens excel in the printing of many electronic materials on rigid and flexible PCBs. These materials include solder masks and resists, fluxes and solder pastes, and especially conductive inks (silver, carbon, silver chloride), and dielectric inks, both used to form conductive traces, capacitor and resistor elements.
MPM stencil printers pioneered Surface Mount Technology (SMT) solder paste printing and continue to lead the industry in performance and excellence in printing electronic materials, including SMT Solder Paste.
PrintingMPM printers are high-speed, high-precision systems for depositing precise patterns of solder paste on printed circuit boards through foil stencils. Available in a wide range of capabilities.Best-in-class printing performance has always neen a hallmark of MPM printing technology, the recognized world standard for reliability, throughput, and high yields.