Phase Change Materials Used In Electronics Temperature Controlling

There are two tendencies in electronics, one is the operating rate getting faster and faster,the other is the chip is designed to be more integrated. Hence, the electronics heat flux ismade so density that heat dissipation of the electronics become a bottleneck of the electronicsindustry development. Phase change materials used in electronics heat dissipation utilize thelatent heat absorbing the heat released by electronics. With the huge latent heat, variablephase-transition temperature and small temperature variation during phase transition, theelectronics can be maintained in a suitable temperature for a long time.Organic acid and paraffin with a phase-transition temperature of58-60℃were chosen asexperimental materials. And, furthermore, using expanded graphite as matrix, the organic acid/expanded graphite and paraffin/expanded graphite composite material were prepared. Theproperties of phase change materials were characterized by Different Scanning Calorimeter,Thermo gravimetric Analysis, Hot Disk Thermal Analyzer and Polarization OpticalMicroscope. The results show that the chosen materials own huge latent heat and goodthermal stability, and the composite phase change materials have high thermal conductivitiesand stable figuration.Experiment have done to test the performance of the electronics cooling systems withphase change materials. The results show that heat sinks fill up with phase change materialscan increase the temperature controlling time of the chip, for example, when the ambienttemperature is50℃and heat dissipation power of5W,10W,15W,20W and25W, no.1heat sink filled with paraffin can extend the temperature controlling time for100%,42%,31%,42%and75%, respectively. The well designed heat sinks can maintain the chip temperaturein a appropriate range for a long time even at the harsh conditions, for example, no.1and no.4heat sinks filled with paraffin can maintain the appropriate chip temperature for over30minat the ambient temperature of50℃and heat dissipation power of25W.Heat sinks filled with pure phase change materials and composite phase change materialshave the similar heat dissipation performance when they have same latent heat. But compositephase change materials are the superior choices considering their fast thermal response andstable figuration. When the heat dissipation power is lower than10W, the paraffin and paraffin/expandedgraphite composite material are the better phase change materials used for electronics coolingthan organic acid. However, when the heat dissipation power is higher than15W or theambient temperature is exceed60℃, the organic acid and organic acid/expanded graphitecomposite material perform better than paraffin.