The 20 µm lithography process was the semiconductor process technology used by semiconductor companies during the early 1960s. 20 µm was roughly the pitch between the centers of two smallest-sized transistors. The typical wafer size for this process at companies such as Fairchild was 0.875 inch (22 mm). The standard transistor packages those years were the TO-5 and TO-18 (Transistor Outline) metal-can packages.

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