SMT007 Magazine

SMT007-Nov2020

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58 SMT007 MAGAZINE I NOVEMBER 2020 Feature by Happy Holden I-CONNECT007 Editor's Note: This article was originally pub- lished in CircuiTree Magazine in June 2006. Happy Holden has made some minor updates, but the foundations of test and inspection in electronics manufacturing are essentially unchanged. This article serves as a solid intro- duction and an effective refresher on the tenets of test and inspection. Ever wonder how you are going to improve profits? One way is to understand your pro- cesses, what causes your yield losses, and how your boards perform. The best tools I know for doing this are the many parametric analy- sis and characterization coupons that are avail- able. These are part of the quality assessment process. These processes cover reliability eval- uations, end-product evaluation, work-in-pro- cess product evaluations, and process param- eter evaluations. Here are the six coupon systems I will explain in more detail: 1. Parametric test system (PTS) 2. Conductor analysis technology (CAT) 3. Printed circuit quality and relative reliability (PCQR 2 ) 4. Highly accelerated thermal shock (HATS) 5. Interconnect stress test (IST) 6. PerfectTest Why Is This Important? With so many different part numbers run- ning through your production, it is difficult to know how well your process is running. This finds its most extreme challenge in integrated circuit (IC) production. One way that IC man- ufacturers know their process is running cor- rectly is to measure specific coupons on a para- metric die that is placed on each wafer and to have specific parametric wafers. Probe stations can be set up at specific pro- cess steps to probe these parametric dies to provide feedback as to whether the process is running in control bounds. Having a specific coupon that is sensitive to a specific process is like the proverbial canary in a coal mine. It sig- nals a problem with the process before it hurts the product. The accumulation of these pro- cess effects, as well as the design, will be dem- onstrated at final test with the characteristic first-pass yield (FPY). Passing the Test

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