The ideal electronic component is one that maintains the manufacturer's guaranteed performance characteristics regardless of the conditions of use. It must be free from any change in performance or defects throughout a period of time that far exceeds the lifetime of the circuit or electronic system in which it will be used. Obviously this represents an ideal situation. The user or customer will rightly demand, however, that the characteristics of components supplied by the manufacturer remain compatible with the overall estimated lifetime of the circuit in a normal environment. Military applications, for example, require that the components used in weapons or transmissions systems are able to function continuously at their nominal levels of operation for thousands of hours in a hostile environment (temperatures of between 50 and +125 C, humidity, salt mist, ionizing radiation, intense vibrations, etc.).

The manufacturer must therefore guarantee that a component will operate correctly under the conditions stipulated by the customer. To achieve the desired result, the manufacturing process incorporates a number of steps designed to obtain high performance and satisfactory reliability while minimizing costs. These steps are summarized below.

1. Performance of the component family. Proper performance implies that the component is able to operate within the stated limits of tolerance (precision, TCR, noise, etc.) as a function of time, temperature, humidity, and vibration, and avoid catastrophic failures.

2. Determination and objectives of quality testing. Tests are designed to provoke potential defects, study their causes, establish relevant correlations, specify the conditions under which quality control should...