Thermal investigation of LED lighting module

The performance of compact thermal models for LED package

In this paper we describe a novel thermal characterization method of GaN-based Light Emitting Diode (LED) package driven under the Alternating Current (AC) mode. The result was compared with the results from the thermal analysis for LED package operated under the Direct Current (DC) condition. Different from the DC condition, the junction temperature rise with the operation time of LED package was exhibited in a band formation. Finite Volume Method (FVM) was utilized to calculate the thermal performance of LED package under the AC condition using the input power extracted from the output current and voltage from the AC power supply. The experimental result was in a good agreement with the simulation data.

Thermal analysis of high power LED packages under the alternating current operation

Thermal analysis of LED spot lighting device operating in external natural or forced heat convection

We have demonstrated the lateral multifinger-type Schottky barrier diode (SBD) with bonding pad over active structure fabricated on the AlGaN/GaN heterostructure prepared on sapphire substrate. The fabricated GaN-SBD with size of 9 mm2 exhibited excellent device characteristics such as forward current of 4.5 A at 1.5 V, leakage current of 6 μA at 600 V, and high breakdown voltage of 747 V. The temperature variations of GaN-SBD for the reverse recovery characteristics are negligible and the value of reverse-recovery charge (Q)rr of GaN-SBD is one twentieth of Si-diode at 175°C.

AlGaN/GaN-Based Lateral-Type Schottky Barrier Diode With Very Low Reverse Recovery Charge at High Temperature

Thermal transient measurements of high power GaN-based light-emitting diodes (LEDs) with multichip designs are presented and discussed in the paper. Once transient cooling curve was obtained, the structure function theory was applied to determine the thermal resistance of packages. The total thermal resistance from junction to ambient considering optical power is 19.87 K/W, 10.78 K/W, 6.77 K/W for the one-chip, two-chip and four-chip packages, respectively. The contribution of each component to the total thermal resistance of the package can be determined from the cumulative structure function and differential structure function. The total thermal resistance of multichip packages is found to decrease with the number of chips due to parallel heat dissipation. However, the effect of the number of chips on thermal resistance of package strongly depends on the ratio of partial thermal resistance of chip and that of slug. Therefore, an important thermal design rule for packaging of high power multichip LEDs has been analogized.

Lan Kim

Papers

Thermal Resistance Measurement of LED Package with Multichips