Dynamic Measurement of the Water Vapor Content of Integrated Circuit Packages using Derivative Infrared Diode Laser Spectroscopy

There has been considerable effort devoted to developing techniques for measuring the moisture content of hermetically sealed integrated circuit packages. Three techniques have generally been used for this purpose: 1) mass spectrometric analysis [1], 2) measurement of a suitably calibrated device characteristic [2], and 3) dew point determinations based on d.c. surface leakage or capacitance [3,4]. In this report, a new method [51 which utilizes derivative infrared spectra for quantitating trace amounts of water vapor, in a manner that eliminates the effects of adsorption or desorption in the test cell on the results of the measurements, is described. The technique is applied to the measurement of the water vapor content of "standard' TO-18 cans and 18 pin side brazed ceramic packages. Because of the sensitivity and selfcalibrating nature of this technique, it can accurately measure water vapor concentrations in the range of 102 to 104 ppm from 50 AQ volumes.