Process Window Index

Process Window Index (PWI) is a statistical measure that quantifies the robustness of a manufacturing process which involves heating and cooling, known as a thermal process. In the electronics manufacturing industry, PWI values are used to calibrate the heating and cooling of soldering jobs (known as a thermal profile) while baked in a reflow oven.

PWI measures how well a thermal process fits into a user-defined process limit known as the specification limit. The specification limit is the tolerance allowed for the process and is statistically determined. In the electronics industry, these specification limits are known as the process window, and values that a plotted inside or outside this window are known as the process window index.

Using PWI values, thermal processes can be accurately measured, analyzed, compared, and tracked at the same level of statistical process control and quality control available to other manufacturing processes.