Electrical and Computer Engineering ETDs

Publication Date

5-14-1968

Abstract

ABSTRACT

The purpose of the work described in this report was to develop a technique for determining the mechanical robustness of small electronic components when subjected to short duration stress waves. Techniques employed by other experimenters., which include flyer­plate impaction and pulsed-electron deposition., are difficult to control and to analyze. The procedure described herein overcomes these difficulties by restricting the variables that control accuracy to those which can be precisely measured.

The wave equation was derived and solved for deformable bodies subjected to unidimensional strain. In addition to providing insight into the dependence of high-tensile stress es on stress -wave characteristics and component geometry, these calculations suggested the laboratory technique that was used. Stress waves were generated by depositing a burst of high-energy electrons into an aluminum absorber. The stress wave was acoustically coupled into transistors., which were chosen as the vehicle for this experiment., by clamping the bottoms of their headers to the rear surface of the absorber. Catastrophic mechanical failures were induced in nine out of ten classes of transistors.

Analysis of the experimental results was performed by using a stress-wave-analyzing computer program to simulate the response of the absorber-transistor assembly to the stress input. Using the stress waveform measured by a quartz gauge clamped to the absorber., the computer was programmed to calculate the stresses that prevailed at the locations of observed failure􀀏 By varying the amplitude of the input stress., it was possible to determine the threshold of stress that caused failure in nine classes of transistors. These thresholds for all observed failures are tabulated.

Suggestions for refinement of the technique and for its extension to other types of electronic components are made. Examples of the use of the results to increase the robustness of transistors are also presented. Appendix A explains one of the disadvantages of using explosively driven flyer plates to generate stress waves in transistors. Details of the SWAP-7 computer code that are relevant to its use with the reported technique, including formulas necessary for calculating the input data., are presented in Appendix B.

Document Type

Thesis

Language

English

Degree Name

Electrical Engineering

Level of Degree

Masters

Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Harold Dean Southward

Second Committee Member

Harold Cates

Third Committee Member

Arnold Herman Koschmann

Fourth Committee Member

William Jackson Byatt

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