Thermal and mechanical analysis of delamination in GaN-based light-emitting diode packages

Hu, Jianzheng; Yang, Lianqiao; Hwang, Woong Joon; Shin, Moo Whan

doi:10.1016/j.jcrysgro.2005.12.049

Cited by 74 publications

(30 citation statements)

References 4 publications

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“…The convection boundary meets the following equation [11] : (1) where, is the temperature gradient near the boundary,  the thermal conductivity, h the thermal convection coefficient between the LED surface and the air, t w the temperature near the boundary, and t f the temperature of the air. The field variable T(x, y, z, t) of the transient temperature field in the three-dimensional Cartesian coordinate system meets the following equation [12] : (2) where, , and are the temperature gradient along x, y and z direction respectively, λ xx , λ yy and λ zz the thermal conductivity, q 0 the heat generate of the unit volume, ρc the density multiplied by the specifi c heat capacity, and the change rate of temperature with time.…”

Section: Methodsmentioning

confidence: 99%

Thermal performance analysis of LED with multichips

Han

Guo

Zhang

et al. 2011

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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The package and system level temperature and thermal stress distributions of 10 W light emitting diode (LED) with 4 chips and 100 W LED with 100 chips were investigated using finite element analysis. The chips were arranged on a Si sheet which is soldered on the copper/diamond composite slug with very high conductivity. The experimental results show that the maximal temperature appears in the chips of both two high power LEDs packages. Compared with the 10 W LEDs package with 4 chips array, the heat issue caused by stacking and coupling of the heat in 100 W LEDs package with 100 chips array is more serious. The chip temperature in the center of the array is much higher, and it decreases with the distance between the chip and the center of LEDs increases. Great thermal stress lies between the chips and the solder, which will reduce the reliability of the package.

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Section: Methodsmentioning

confidence: 99%

Thermal performance analysis of LED with multichips

Han

Guo

Zhang

et al. 2011

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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“…For the heatblock test, the boundary condition is to apply heat-transfer coefficient, combining convection and radiation heat transfer, to the external surfaces of the LED package. The whole heattransfer coefficient varies with the temperatures of different surfaces of the package, and the ambient temperature is fixed at 270 • C. The thermal parameters of LED packaging materials are listed in Table I [5]. The modeled LED package has a dimension of 5.06 × 5.06 × 0.95 mm 3 , and the package is composed of chip, heat slug, leadframe, ceramic mold, and epoxy lens, as shown in Fig.…”

Section: B Thermal Modelingmentioning

confidence: 99%

“…Furthermore, LED packages have to experience several thermal cycles during the surface-mounting process. Delamination is possibly induced in the mounting process and is directly responsible for mechanical-reliability problems [5]- [7]. A good package design by using proper materials and structures is important to ensure both the thermal and mechanical reliabilities of LED packages.…”

Section: Introductionmentioning

confidence: 99%

Thermal and Mechanical Analysis of High-Power LEDs With Ceramic Packages

Yang

Shin

2008

IEEE Trans. Device Mater. Relib.

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In this paper, we present the thermal and mechanical analysis of high-power light-emitting diodes (LEDs) with ceramic packages. Transient thermal measurements and thermomechanical simulations were performed to study the thermal and mechanical characteristics of ceramic packages. Thermal resistances from the junction to the ambient were decreased from 79.6 to 46.7 • C/W by replacing the plastic mold with a ceramic mold for LED packages. Thermomechanical stress induced in the heat-block test was simulated using a finite-element method. Higher level of thermomechanical stress in the chip was found for LEDs with ceramic packages, despite less mismatching coefficients of thermal expansion, compared with that with plastic packages. The thermomechanical-stress components in the direction of the thickness were found to be larger than that in other two directions. The results suggest that the thermal performance of LEDs can be improved by using ceramic packages, but the mounting process of the high-power LEDs with ceramic packages is critically important and should be the reason for causing delaminating interface layers in the packages.

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“…What's more, during various manufacturing processes, accelerated testing, inappropriate handling, defects at the interfaces due to the possible contamination or other process control issues may be induced in the early stage of process development and they may grow quickly, which would deteriorate the interfacial situation. Generally, reliability of the LED device is highly dependent on their packages' thermal management since high junction temperature not only decreases the conversion efficiency from electrical to optical power greatly but also induces high stress in LED packaging [2]. Once initial cracks were induced or delamination propagated in a relatively large size, air or moisture can be inevitably introduced at these spaces and junction temperature can increase substantially, which can prevent heat from dissipating outside efficiently and cause the devices to fail to work with a very short life span.…”

Section: Introductionmentioning

confidence: 99%

Analyses of propagation behavior of crack at interface between die-attach and Cu base and cracks' effects on reliability of high brightness light-emitting diode (LED)

Gao

et al. 2013

2013 IEEE 63rd Electronic Components and Technology Conference

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Reliability problems heavily hinder light-emitting diode (LED), especially high brightness LED, from developing rapidly and putting into mass production. One of the most important reasons is that it has so many interfaces which are always the weakest places. LED chip's working temperature is about 90°C and the high mismatch of coefficient of expansion of different materials can inevitably cause failures, such as delamination at the interfaces. What's more, due to inappropriate manufacturing processes, defects, like cracks and delaminations, are often generated in LED devices before they reach customers, which would propagate at a fast pace and bury a potential threat causing the device to fail to work. In this paper, delaminations between die attach and copper heat sink are analyzed by finite element analysis (FEA). Different sizes are considered to investigate how the crack propagates and the results show that the crack can easily propagate at first, but it would be a little more difficult and finally the crack is so long that there is little chance to propagate, if the crack growth is stable, or if the strain energy release rate gets smaller. Furthermore, two kinds of die adhesives, lead free solder and sintered silver paste, are selected and analyzed under the same conditions and it is found that they follow a similar propagation behavior, but cracks in sintered silver paste has much lower strain energy release rate. Effect of interfacial delamination on thermal performance is also investigated and it is found that delaminations have a great impact on LED's thermal resistance.

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Thermal and mechanical analysis of delamination in GaN-based light-emitting diode packages

Cited by 74 publications

References 4 publications

Thermal performance analysis of LED with multichips

Thermal performance analysis of LED with multichips

Thermal and Mechanical Analysis of High-Power LEDs With Ceramic Packages

Analyses of propagation behavior of crack at interface between die-attach and Cu base and cracks' effects on reliability of high brightness light-emitting diode (LED)

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