The electrical-thermal characteristics of gallium-nitride- (GaN-) based light-emitting diodes (LED), packaged by chips embedded in board (EIB) technology, were investigated using a multiphysics and multiscale finite element code, COMSOL. Three-dimensional (3D) finite element model for packaging structure has been developed and optimized with forward-voltage-based junction temperatures of a 9-chip EIB sample. The sensitivity analysis of the simulation model has been conducted to estimate the current and temperature distribution changes in EIB LED as the blue LED chip (substrate, indium tin oxide (ITO)), packaging structure (bonding wire and chip numbers), and system condition (injection current) changed. This method proved the reliability of simulated results in advance and useful material parameters. Furthermore, the method suggests that the parameter match on Shockley's equation parameters, , , and , is a potential method to reduce the current crowding effect for the EIB LED. Junction temperature decreases by approximately 3？K to 10？K can be achieved by substrate thinning, ITO, and wire bonding. The nonlinear-decreasing characteristics of total thermal resistance that decrease with an increase in chip numbers are likely to improve the thermal performance of EIB LED modules. 1. Introduction Numerous simulation studies of gallium-nitride- (GaN-) based light-emitting diodes (LED) have been proposed to overcome the technical challenges in high power LED lighting [1–4]. These include thermal management, electric drive, and light extraction as well as insights into microscopic carrier transfer mechanisms [5], such as efficiency droop [6]. However, most of these studies focused on the electric, optical, or thermal problems of a single LED using a single physical field code, for instance, ANSYS [7], or general-purpose semiconductor optoelectronic simulator, such as SYNOPSYS [8]. These methods bring high-power lighting application inconvenience for simulating multichips packaged LED arrays with multiphysical field and multiscale properties [9]. Based on the proposed chips in board packaging method, where the aluminum- (Al-) core printed circuit boards (Al-PCB) with 9 round holes are embedded with copper reflectors for integrating chips [10] (see Figure 1), the finite element simulation code COMSOL [11] is adopted to address this demand. The multiphysical field and multiscale COMSOL model for the packaging structure has been proposed. The sensitivity analysis of the current crowding, the temperature distribution, and the thermal resistance to parameters of the
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