Testing and Analysis of Boron-Doped Aluminum Nitride Thin-Film-Coated Al as Thermal Substrates in PCB Fabrication for LED Application

Abstract

Chemical vapor deposition was used to coat boron-doped AlN thin film on Al substrates and used as thermal substrates in the fabrication of printed circuit boards (PCBs). Conventional screen printing method was used to deposit dielectric, conductor, and protective coating on thin-film-coated Al substrate for the printed metal PCBs (MPCBs). Commercial light emitting diode (LED) was fixed on MPCB and tested for thermal and optical properties under various driving currents. The observed results are compared with those of commercial metal-core printed circuit board (MCPCB). The measured total thermal resistance ( $R_{\mathrm {th-tot}})$ of the LED was low for MPCB and recorded good difference in $R_{\mathrm {th-tot}}$ ( $\Delta R_{\mathrm {th-tot}}= 7.55$ K/W) when compared with MCPCB. An impressive difference on rise in junction temperature ( $T_{\mathrm {J}})$ was noticed ( $\Delta T_{\mathrm {J}}= 13.72$ ) with MPCB at 700 mA as compared with MCPCB. As a result of reduced $T_{J}$ , an improved light output was recorded for MPCB in all driving currents and a higher value also with MPCB. Hence, B-AlN thin-film-coated Al substrate could be used as thermal substrates in PCB fabrication for efficient electronic packaging in LED industries.