The influence of the phosphor layer as heat source and up-stream thermal masses on the thermal characterization by transient thermal analysis of modern wafer level high power LEDs

2016 ◽  
Vol 67 ◽  
pp. 29-37 ◽  
Author(s):  
E Liu ◽  
Alexander Hanss ◽  
Maximilian Schmid ◽  
Gordon Elger
Keyword(s):  
Thermal Analysis ◽  
Heat Source ◽  
High Power ◽  
Thermal Characterization ◽  
Wafer Level ◽  
Phosphor Layer ◽  
Transient Thermal Analysis ◽  
Transient Thermal

Transient Thermal Analysis as a Test Method for the Reliability Investigation of High Power LEDs during Temperature Cycle Tests

2013 ◽  
Vol 2013 (1) ◽  
pp. 000902-000907
Author(s):  
Gordon Elger ◽  
Shri Vishnu Kandaswamy ◽  
Robert Derix ◽  
Jürgen Wilde
Keyword(s):  
Thermal Analysis ◽  
Solder Joint ◽  
High Power ◽  
Test Method ◽  
Temperature Cycle ◽  
Electric Resistance ◽  
Transient Thermal Analysis ◽  
Open Contact ◽  
Long Lifetime ◽  
Transient Thermal

Light emitting diodes (LEDs) are today standard and mature light sources. They have several key advantages, like small size, low energy consumption and long lifetime. However, high reliability of the LED system is required to achieve long lifetime of the light source. Thermo-mechanical stress due to temperature cycle causes failure of electronic systems. The electronic component itself or the interconnect device, e.g. printed circuit board (PCB) might fail. In many cases, the weakest link is found to be the solder interconnect between package and the board. Cracking of the interconnect causes an open contact and the system fails. In this paper we compare the existing methods to investigate LED interconnect failures during temperature cycle tests like the simple “light-on-test”, electric resistance measurement and the shear test. We describe and introduce the transient thermal analysis as a measurement method. We present the first reliability data analysis with transient thermal analysis of ceramic high power LED packages on Al-IMS during air to air thermal shock test (−40°C to +125°C) and correlate it with cross sections. We demonstrate the sensitivity of the thermal analysis to detect solder joint failures of the assembly. We compare the results with electric resistance measurements and light on tests and show that the resolution is significantly higher compared to the methods applied today. The sensitivity of the method enables us to detect the crack in a solder joint much earlier than the final failure of the joint, i.e. the open contact.

Transient thermal analysis of InGaAsP-InP high-power diode laser arrays with different fill factors

2005 ◽  
Vol 97 (8) ◽  
pp. 084503 ◽  
Author(s):  
A. Gourevitch ◽  
B. Laikhtman ◽  
D. Westerfeld ◽  
D. Donetsky ◽  
G. Belenky ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Diode Laser ◽  
High Power ◽  
Laser Arrays ◽  
Transient Thermal Analysis ◽  
Transient Thermal ◽  
Power Diode ◽  
High Power Diode Laser

Transient Thermal Analysis as a Highly Sensitive Test Method for the Reliability Investigation of High Power LEDs During Temperature Cycle Tests

2014 ◽  
Vol 11 (2) ◽  
pp. 51-56 ◽  
Author(s):  
Gordon Elger ◽  
Shri Vishnu Kandaswamy ◽  
Robert Derix ◽  
Jürgen Wilde
Keyword(s):  
Thermal Analysis ◽  
Solder Joint ◽  
High Power ◽  
Open Circuit ◽  
Temperature Cycle ◽  
Electric Resistance ◽  
Transient Thermal Analysis ◽  
Printed Circuit ◽  
Long Lifetime ◽  
Transient Thermal

Light emitting diodes (LEDs) are today standard and mature light sources. They have several key advantages such as small size, low energy consumption, and long lifetime. However, high reliability of the LED system is required to achieve long lifetime of the light source. Thermomechanical stress due to temperature cycling causes failure of electronic systems. The electronic component itself or the interconnect device, for example, the printed circuit board (PCB), might fail. In many cases, the weakest link is found to be the solder interconnect between the package and the board. Cracking of the interconnect causes an open circuit and the system fails. In this paper the existing methods are compared in order to investigate LED interconnect failures during temperature cycle tests such as the simple light-on test, electric resistance measurement, and the shear test. This paper describes and introduces transient thermal analysis as a measurement method. This paper presents the first reliability data analysis with transient thermal analysis of ceramic high power LED packages on printed circuit boards, that is, insulated metal substrates, during the air-to-air thermal shock test (−40°C to +125°C) and correlates it with cross sections. This work demonstrates the sensitivity of the thermal analysis to detect solder joint failures of the assembly. This paper compares the results with electric resistance measurements and light-on tests and shows that the resolution is significantly higher compared with the methods applied today. The sensitivity of the method enables the detection of a crack in a solder joint much earlier than the final failure of the joint, that is, the open circuit.

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