Heat Dissipation of Printed Circuit Board by the High Thermal Conductivity of Photo-Imageable Solder Resist

Abstract

Thermal management issues with IC packages have been growing as electronic systems have become smaller with a higher functionality. Since the high junction temperature of IC packages induces the low performance and malfunction of electronic systems, the thermal dissipation capability of electronics is important for stable electrical performance and electro-mechanical reliability. However, the conventional cooling methods that depend on air flow path and heat sink structure is not sufficient to meet the growing thermal requirements of IC packages. Since there is limit on conventional design, such as optimization air flow path and heat sink structure, to dissipate more heat through an exhaust fan system. The main purpose of the present research is to reduce the junction temperature of the IC package by using a Printed Circuit Board (PCB) coated with new Photo-imageable Solder Resist (PSR) that has high thermal conductivity. The thermal conductivity of the newly developed PSR is about five times as high as that of the conventional PSR for PCB(0.23∼0.25W/m·K). The PCB was prepared by the EIA/JEDEC standard, JESD51-7. Experimental and finite element analyses were performed to investigate the effect of SR on thermal dissipation capability. The experimental and FE results show that the high thermal conductivity of PSR can reduce the steady-status regulator surface temperature by about 3∼8K as an air flow conditions around PCB. Also, the high thermal conductivity of SR is more effective under a low air heat transfer coefficient condition. Therefore, it is believed that an improved heat transfer with a PSR of high thermal conductivity should provide stable electrical performance for the IC package.