Environmental stress screening process with liquid coupled vibration

An environmental stress testing system for stress testing circuit boards mounted in a carder, comprising:

• a hot inert liquid bath that is maintained at a temperature of in excess of 50.degree. C.;
• a cold inert liquid bath that is maintained at a temperature of less than -0.degree. C.;
• a controller for controlling the environmental stress testing system;
• apparatus for transferring the carder between the cold inert liquid bath and the hot inert liquid bath under control of the controller;
• power supplies for applying maximum power voltages to the circuit boards in the carrier under control of the controller;
• an acoustical transducer system for applying mechanical vibrations to the circuit boards via the hot inert liquid bath and the acoustical transducer system comprises a first and second acoustical transducers with the first acoustical transducer producing low frequency mechanical vibrations in response to the electrical frequency signals with the resulting mechanical vibrations in a range of 20 Hz to 20 kHz and the second acoustical transducer producing high frequency mechanical vibrations in response to the electrical frequency signals with the resulting mechanical vibrations in a range of 20 kHz to 100 kHz so that not only are mechanical failures induced but also molecules within electronic components are excited incurring faster, and more penetrating thermal and electrical stresses;
• and
• a frequency generator for applying electrical frequency signals to the acoustical transducer system to control the mechanical vibrations produced by the acoustical transducer system with the frequency generator being controlled by the controller.