Multiple heat path dynamic thermal compact modeling for silicone encapsulated LEDs

A new multiple heat path dynamic compact model extraction method for LED packages with silicone domes is proposed. The method enables separate characterization of the LEDs dome and the main heat path. It is based on thermal transient analysis of LED configurations with and without the dome. The heat paths de-embedding procedure proposed significantly increases accuracy of the LED thermal characterization compared to a typical singular heat path approach. The method is demonstrated with a representative mid-power LED. The results are validated with steady-state FEA. Suppressed estimation errors of the heat path evaluation are indicated

Multiple heat path dynamic thermal compact modeling for silicone encapsulated LEDs

\u3cp\u3eA new multiple heat path dynamic compact model extraction method for LED packages with silicone domes is proposed. The method enables separate characterization of the LEDs dome and the main heat path. It is based on thermal transient analysis of LED configurations with and without the dome. The heat paths de-embedding procedure proposed significantly increases accuracy of the LED thermal characterization compared to a typical singular heat path approach. The method is demonstrated with a representative mid-power LED. The results are validated with steady-state FEA. Suppressed estimation errors of the heat path evaluation are indicated.\u3c/p\u3

Requirements specification for multi-domain LED compact model development in Delphi4LED

Light-emitting diode (LED) technology has been rapidly developing due to high energy efficiency and longer lifetimes of LED luminaires. One of the main challenges in designing LED components is to manage the inter-twined relation between thermal, electrical, and optical performances. These dependencies are required to be well understood in order to operate LEDs efficiently and have accurate performance prediction at different levels of the product value chain. Delphi4LED project aims at developing standardised method to create multi-domain (thermal, electrical, and optical) compact models from the measurement data. To obtain highly reliable and representative data sets via characterisation and calibration, end-user requirements specification for diverse LED samples are needed. In this paper, we report the lists of LED parameters and components selected for measurements, simulation and calibration considering end-user needs. We also show some of the methodologies for compact thermal model development that are recommended in Delphi4LED, followed by definition of simulation benchmark problems

Reliability and Failures in Solid State Lighting Systems

Reliability is an essential scientific and technological domain intrinsically linked with system integration. Nowadays, semiconductor industries are confronted with ever-increasing design complexity, dramatically decreasing design margins, increasing chances for and consequences of failures, shortening of product development and qualification time, and increasing difficulties to meet quality, robustness, and reliability requirements. The scientific successes of many micro/nano-related technology developments cannot lead to business success without innovation and breakthroughs in the way that we address reliability through the whole value chain. The aim of reliability is to predict, optimize, and design upfront the reliability of micro/nanoelectronics and systems, an area denoted as “Design for Reliability (DfR)”. While virtual schemes based on numerical simulation are widely used for functional design, they lack a systematic approach when used for reliability assessments. Besides this, lifetime predictions are still based on old standards assuming a constant failure rate behavior. In this chapter, we will present the reliability and failures found in solid-state lighting systems. It includes both degradation and catastrophic failure modes from observation toward a full description of its mechanism obtained by extensive use of acceleration tests using knowledge-based qualification methods.Electronic Components, Technology and MaterialsMechanical, Maritime and Materials Engineerin

Reliability and Failures in Solid State Lighting Systems

Reliability is an essential scientific and technological domain intrinsically linked with system integration. Nowadays, semiconductor industries are confronted with ever-increasing design complexity, dramatically decreasing design margins, increasing chances for and consequences of failures, shortening of product development and qualification time, and increasing difficulties to meet quality, robustness, and reliability requirements. The scientific successes of many micro/nano-related technology developments cannot lead to business success without innovation and breakthroughs in the way that we address reliability through the whole value chain. The aim of reliability is to predict, optimize, and design upfront the reliability of micro/nanoelectronics and systems, an area denoted as “Design for Reliability (DfR)”. While virtual schemes based on numerical simulation are widely used for functional design, they lack a systematic approach when used for reliability assessments. Besides this, lifetime predictions are still based on old standards assuming a constant failure rate behavior. In this chapter, we will present the reliability and failures found in solid-state lighting systems. It includes both degradation and catastrophic failure modes from observation toward a full description of its mechanism obtained by extensive use of acceleration tests using knowledge-based qualification methods

ZnO/AlGaN Ultraviolet Light Emitting Diodes

We report on the optical and electrical properties of n-ZnO/p/-AlGaN heterojunctions. Ga doped n-type ZnO layers were grown using chemical vapor deposition on Mg doped p-type AlGaN epitaxial layers. AlGaN epitaxial layers with 12 at.% Al were grown on 6H-SiC by hydride vapor phase epitaxy. Rectifying diode-like behavior with a threshold voltage of 3.2 V was achieved. Intense ultraviolet electroluminescence peaking at a wavelength of 390 nm was observed at 300 and 500 K as a result of hole-injection from the n-ZnO layer into the p-AlGaN layer of the heterostructure