Proposed Solution to the Problem of Thermal Stress Induced Failures in Medical Electronic Systems

Proposed Solution to the Problem of Thermal Stress Induced Failures in Medical Electronic Systems

V. Lakshminarayanan (Research Student, ECE Department, Sri Chandrasekharendra Saraswathi Vishwa Mahavidyalya (SCSVMV) University, Enathur, Kanchipuram, India) and N. Sriraam (Center for Medical Electronics and Computing, M.S. Ramaiah Institute of Technology, Bangalore, India)
Copyright: © 2014 |Pages: 9
DOI: 10.4018/IJBCE.2014070103

Abstract

The concept of miniaturization has propagated to all types of electronic applications. The complexity of electronic systems has been increasing due to increase in the number of functions and features offered to the users. At the same time the number of devices working per unit volume of the system has increased enormously, due to which the power density per unit volume has increased. Dissipating high power in small volumes has increased the thermal problems in all types of electronic systems, including medical gadgets. Thermal stress has been identified to be the major cause of failure of electronic devices in electronic systems, based on the analysis of failures, based on research work. The causative mechanism of failure of semiconductor device package due to thermal overstress in medical electronic systems is the differential expansion between plastic and metal parts of the device which causes a differential strain and package failure. Selection of materials with similar coefficient of thermal expansion is important to prevent thermal overstress caused failures. In this paper, we discuss a technique which uses mathematical analysis to provide a solution to this problem of selecting the suitable material to prevent differential thermal stress failures in medical electronics systems.
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1. Introduction

Miniaturization in medical electronic devices has increased the complexity, device density and power dissipation per unit volume. This is as a result of increase in the number of functions offered by the system to the users. Heat is generated in medical electronic systems just as in the case of other electronic products and cooling methods are used to control the same. Semiconductor devices used in electronic systems are highly sensitive to temperature. Based on the research carried out by various users it has been found that among the various failure mechanisms occurring in semiconductor devices, thermally induced failures constitute a large percentage of the total as mentioned in Renesas Electronics (2010) and Electronic Design (2015).Hence there is a need to address this major problem to reduce failures in electronic systems Reliability Handbook (2000). Thermal stress could arise in a system for various reasons such as higher ambient temperature, thermal shocks (subjecting the device to extremes of temperature within a short time),over-loads, high power density due to system complexity, malfunctioning of components having a secondary effect leading to electrical overstress (EOS) and then thermal overstress, component defects, assembly faults, lack of proper cooling arrangements, and such reasons.

Temperature ranges of operation are defined for electronic components used in various applications. For example: commercial: 0° to +70°C, extended commercial: -10°C to +70°C, industrial: -40°C to + 85°C, automotive: -40°C to +125°C and the like. The junction temperature of a device depends on the following factors during its operation:

  • I.

    Power dissipated in the device

  • II.

    Ambient temperature

  • III.

    Thermal resistance from the junction to the ambient

The junction temperature of the semiconductor device should be kept within the limit depending on the material, within these operating temperature ranges.

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