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24 SMT007 MAGAZINE I NOVEMBER 2021 is the number you need to use for that specific assembly. at brings up another important point: you need to qualify each product individually due to differences in component architecture/den- sity and thermal mass. Each board has its own unique set of parameters that can and most like- ly will yield a different result in the ROSE tes- ter. is is similar to why I say you should nev- er profile an empty reflow oven when switch- ing paste types. It's not a bad idea to do that for calibration/verification of an oven, but when you fill that oven with boards the thermal load will have an impact that should be measured on a fully populated assembly at critical loca- tions. Just as the 1.56 µg/cm 2 cleanliness crite- ria was a bad idea to use on all assemblies, it is an equally bad idea to use a bare board to veri- fy a reflow profile and then apply that recipe to all boards built with that paste. A little off top- ic, but still important when trying to achieve a qualified manufacturing process. I fully believe that removing the 1.56 µg/cm 2 criteria will improve overall quality and reli- ability of electronics as time goes on, as it forc- es us all to take a much closer look at how res- idues impact the products being built today. I also believe that it's not as difficult as some may think. I know for sure that the information on how to create the objective evidence is readi- ly available in the J-STD-001H Section 8.0 and WP-019B. As I have said many times, you are responsible for the quality and reliability of your own processes but this revision from the IPC will go a long way in helping you increase both. SMT007 References 1. Objective Evidence,, February 7, 2000. 2. How CERN Made High Quality Electronics in the 1970s, Hackaday. Eric Camden is lead investigator at Foresite, Inc. The Printed Circuit Assembler's Guide to… Solder Defects—the latest title in the I-007eBook library—is specifically dedicated to educating the printed cir- cuit board assembly sector and serves as a valu- able resource for people seeking the most relevant information available. Solder defects in surface-mount assembly have been an issue for decades. The combined challeng- es of Pb-free soldering and ever-increasing minia- turization have resulted in new or exacerbated de- fects in electronics assembly, but there are proven ways to avoid these defects. Indium Corporation's Christopher Nash and Dr. Ronald C. Lasky address the top six defects, as well as how to avoid them. This includes minimiz- ing voiding, head-in-pillow and non-wet opens, and tombstoning of passive components. According to industry veteran Joe O'Neil, former owner/CEO of Hunter Technology, The Printed Cir- cuit Assembler's Guide to… Solder Defects is "an out- standing summary of the whys and hows of paste the- ory, defect causation, and recommended best practic- es. This short read contains real-world advice from the experts. I highly recommend it for anyone in- volved in the PCB assembly process." This book will be especially beneficial to PCB as- semblers in improving their assembly processes and the reliability of the end-product, eliminating field failures, and reducing costs. Download your free copy today! Please visit our full library here. For more information, contact: Barb Hockaday, I-Connect007 eBooks, +1-916-365-1727 (Pacific) Learn How to Avoid Solder Defects With New Book Authored by Indium Corporation

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