Geometric Dimensioning and Tolerances (GD&T) is the engineering language used to describe the allowable variances of form, fit, and function for features beyond that which can be adequately and economically controlled by traditional rectilinear and angular dimensions and tolerances.

Semiconductor component and socket manufacturer specifications both use GD&T to insure their fit and function mechanically together to allow for electrical contact in extreme temperature environments.

This new tutorial is presented in four sections: Section one provides a highly abbreviated “How to Spell GDT” review of the fundamentals of GD&T. Section two shows the aspects of GD&T that are typically used by semiconductor professionals. Section three provides detailed instructions of how to measure GD&T. Section four describes the changes and clarifications in the recent updates to the ASME Y14.5 GD&T standard.