Issue link: https://iconnect007.uberflip.com/i/1207026
102 SMT007 MAGAZINE I FEBRUARY 2020 Article by Pete Starkey I-CONNECT007 "I'm a hands-on person who likes to do hands-on stuff to understand technology and how defects occur." This was how Bob Wil- lis described his personal methodology as he presented a comprehensive and informa- tive online webinar on solder paste basics. A specialist in PCB soldering processes, design for manufacturing, and failure analysis since his early days with GEC-Marconi, Willis has been involved with the introduction and implementation of lead- free soldering technol- ogy since the turn of the century, providing "how to do it," hands-on, lead- free training workshops and winning awards from SMTA and IPC for his industry support. "Solder paste quality and performance is important, and considerable engineering goes into its production. Selecting the best materi- als for your product and assembly process is key to high yield and your customers' satisfac- tion," said Willis. He continued, "Solder paste must be compatible with your equipment and other processes you use like cleaning, coating, and electrical testing. Working with suppliers to achieve the best performance is vital, but so is a periodic review of materials used. There are always improvements being made to print- ing and jetting technology, and it is important that engineers consider if there are technical or commercial reasons to change. We look at common testing methods and some of the sim- ple shop floor techniques used over the years to understand the different types of process failures." Based on his own industry surveys, Willis had ascertained that solder paste printing and reflow soldering accounted for a substantial proportion Solder Paste Evaluation and Simple Tricks of the Trade Checking paste spitting and condensation. Bob Willis