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50 The PCB Magazine • July 2016 by Patrick Valentine UYEMURA USA Measurement capability is a critical aspect of ensuring product quality, therefore a mea- surement system must be assessed before being used on products. Understanding how to assess measurement capability becomes critical. The Type 1 Gauge study is typically the first step in a measurement system analysis program. Type 1 Gauge parameters are explained, and a worked example using electroless nickel immersion gold (ENIG) is provided. What Does the Type 1 Gauge Study Do? There are two major types of measurement system variation: 1. Accuracy is variation between the measurement and a true or reference value 2. Precision is variation between repeated measurements A Type 1 Gauge study involves repeated measurements of one sample by one gauge and by one operator. With this information, the Type 1 Gauge study provides an assessment of the following: 1. Accuracy, assuming a reference value is available 2. Precision of repeated measurements Without an accepted reference value, the Type 1 Gauge study only measures precision, and accuracy becomes unavailable. Bias is a quantitative term used to describe accuracy. Bias is the difference between the average of measurements made on the reference value and its true value. A Type 1 Gauge study considers only the inherent variation of the gauge itself. A Type 1 Gauge study isolates the effects of accuracy and precision, and evaluates the capability of the gauge to make accurate measurements with acceptable variability. A Type 1 Gauge study does not assess operator-to-operator or gauge- to-gauge variation. A more complex gauge re- peatability and reproducibility (R&R) study is indicated for a more comprehensive measure- ment system analysis. Gauge resolution is the gauge's smallest increments of measure. For the Type 1 Gauge FEATURE

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