Analysis of thermal characteristics and mechanism of degradation of flip-chip high power LEDs

Abstract The purpose of this study is to investigate the thermal behavior at the die-attached interfaces of flip-chip GaN high-power light emitting diodes (LEDs) using a combination of theoretical and experimental analyses. The results indicate that contact thermal resistance increased dramatically at the die-attached interfaces with aging time and stress, degrading the luminous flux. The junction temperature and thermal uniformity of the flip-chip structure both strongly depend on the arrangement of gold bumps. Local hot spots effectively reduce light output under high electric and thermal stress, influencing the long-term performance of the LED device. The results were validated using finite element analysis and in experiments using an infrared and an emission microscope. A two-step thermal transient degradation mode was identified under various aging stresses. A simulation further optimized the bump configuration that was associated to yield a low junction temperature and high temperature uniformity of the LED chip. Accordingly, the results are helpful in enhancing the performance and reliability of high-power LEDs.

[1]  Michael Pecht,et al.  Electromigration and thermomigration behavior of flip chip solder joints in high current density packages , 2008 .

[2]  M. Rencz,et al.  Increasing the accuracy of structure function based thermal material parameter measurements , 2005, IEEE Transactions on Components and Packaging Technologies.

[3]  M. Rencz,et al.  Structure function evaluation of stacked dies , 2004, Twentieth Annual IEEE Semiconductor Thermal Measurement and Management Symposium (IEEE Cat. No.04CH37545).

[4]  Lianqiao Yang,et al.  Thermal and mechanical analysis of delamination in GaN-based light-emitting diode packages , 2006 .

[5]  Chien-Ping Wang,et al.  Failure and degradation mechanisms of high-power white light emitting diodes , 2010, Microelectron. Reliab..

[6]  Jao-Hwa Kuang,et al.  Failure Mechanisms Associated With Lens Shape of High-Power LED Modules in Aging Test , 2008, IEEE Transactions on Electron Devices.

[7]  Mehmet Arik,et al.  Thermal management of LEDs: package to system , 2004, SPIE Optics + Photonics.

[8]  M. Vanzi,et al.  Accelerated Life Test of High Brightness Light Emitting Diodes , 2008, IEEE Transactions on Device and Materials Reliability.

[9]  Andras Poppe,et al.  New approaches in the transient thermal measurements , 2000 .

[10]  K. Streubel,et al.  Identification of aging mechanisms in the optical and electrical characteristics of light-emitting diodes , 2001 .

[11]  Lianqiao Yang,et al.  Mechanism and thermal effect of delamination in light-emitting diode packages , 2005, Microelectron. J..

[12]  Hyun-Ho Kim,et al.  Thermal transient characteristics of die attach in high power LED PKG , 2008, Microelectron. Reliab..

[13]  Nadarajah Narendran,et al.  Characterization of thermal resistance coefficient of high-power LEDs , 2006, SPIE Optics + Photonics.

[14]  Jong Hwa Choi,et al.  Thermal analysis of LED array system with heat pipe , 2007 .

[15]  P. V. Varde,et al.  Light emitting diodes reliability review , 2012, Microelectron. Reliab..