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Panel Cooling Units

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Effect of heat on electronic devices

10°C – twice law

It has proven by data that in semiconductor and electronic parts, failure rate hugely increases depending upon heat and life shortens. Graph (1) shows change in control panel internal temperature and panel external temperature of personal car manufacturer. Temperature difference of 15 ~ 20°C at the beginning and at the end was generated even in a survey of September 2002.
Machine and panel are further downsized with miniaturization of electronic machines. Heat generation itself tends to increase, which affects electronic machines. In a panel in which panel inside temperature becomes 55°C or 60°C, life of condenser used in electronic machine shortens tremendously as shown in graph (2).

Graph (2) shows “relationship between temperature of electrolytic condenser and life”. At 300C temperature, life of electrolytic condenser is about 80000 hours while at 40°C temperature, it is 40000 hours. In other words, it becomes half. Further at 60°C temperature, it lowers by about half becoming about 10000 hours. Life of semiconductor and electronic parts also shortens largely by heat.

“10°C – twice law” ... Life fluctuates twice when temperature changes by 10°C.


relationship between temperature of electrolytic condenser and life


Arrhenius law

Graph (3) shows “relationship between surrounding temperature in semiconductor and failure rate” and Y axis shows acceleration of failure rate. As per this, failure rate at temperature below 30°C is very less however at 40°C temperature, failure rate is 1. It increases 10 times to close to 30 times when temperature becomes 60°C and at 80°C, it rapidly increases 100 times to 300 times. It understood that failure rate of semiconductor and electronic parts rapidly increases depending upon temperature.

relationship between surrounding temperature in semiconductor and failure rate

“Arrhenius law” …Law of temperature dependence of chemical reaction rate of substance.

Arrhenius equation is used for estimating life of parts from temperature.


Strain migration

Joined substance undergoes thermal expansion thereby generating stress(stress) as per respective thermal expansion coefficient. For example, when heat is applied to soldered print substrate, cracks are formed in the soldering of joined surface due to difference in thermal expansion coefficient of joined part and substrate, thereby causing improper connection.
Strain migration

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