Modeling of Thermoacoustic Frequency Characteristics for the Air-Tightness Test Method

Abstract

This paper is a description of theoretical models applied for the numerical interpretation of the experimental amplitude and phase frequency thermoacoustic characteristics observed for the transistor's packaging TO-39 with model holes of known radii in the packaging. They are essential from the point of view of determination of the sensitivity of the thermoacoustic method applied for the measurements of the air-tightness of packagings of electronic elements. In this paper, two models of the thermoacoustic signal are described, which are based on a transformation of the thermoacoustic effect to an electrical circuit: CRC and CRLC. Additionally, a method of extraction of the signal, coming from the hole in the packaging, from the total thermoacoustic signal, of the TO-39 packaging, is presented and discussed. The limitation of this method of detection of the air-tightness, caused by the thermoacoustic signal of the air-tight packaging, is also discussed.