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Top1. 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:
The junction temperature of the semiconductor device should be kept within the limit depending on the material, within these operating temperature ranges.