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92 SMT007 MAGAZINE I SEPTEMBER 2020 If you are one of the long-time readers of SMT007 Magazine, you probably know that there was a print version for decades known as SMT. I was one of the columnists for the print version, starting in the mid-1980s. I was look- ing at some of the columns that I wrote almost a decade ago to see how things have changed over time. It should be no surprise that there have been significant changes in many areas but practically no changes in others. For example, there has been practically no improvement in the percentage of yield despite decades of industry experience in high-vol- ume manufacturing. Obviously, some compa- nies are better than others in achieving higher and consistent quality than others, but overall the yield has not improved in percentage terms over the decades. Less than 10% of companies, OEM or EMS, have over 90% first-pass yield (see my June 2019 column). At a macro level, there are many reasons for this. For example, to keep up with Moore's law, there has been significant shrinkage in size and pitches of packages while still dealing with old packages, including through-hole on the same board. This increases board complex- ity. In addition, during the past two decades, there has been a tremendous increase in out- sourcing by OEMs to EMS companies, which also results in a decrease in yield. This is not because EMS companies are not good at what they do, but as I have explained in previous columns, EMS companies don't have control over some of the key contributors of defects, such as DFM and in many cases incoming material quality. What I want to do in this column and the two follow-up columns is to look into how to assess the manufacturing capability of any company—OEM or EMS. When I say manu- How to Audit OEM-EMS Assembly Capability, Part 1 SMT Solver by Ray Prasad, RAY PRASAD CONSULTANCY GROUP

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