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This paper presents a MEMS particulate matter (PM) sensor for portable air quality detection. The small size (5.2 mm × 4.2 mm × 1 mm) of the sensor allows integration in portable devices. Furthermore, an unsophisticated fabrication process is required which results in higher yield and consequently lower cost. The principle used to detect PM is based on light scattering in a micro fabricated chamber,...
Package free LED, whose characteristics as no leadframe/ reflector, is one of those emerging technology [1]. The package free LED has arose excessive attention in recent years because of its benefits in excellent color consistence, wide light distribution, low material cost and simple process. This study assesses the performance of “sheet forming type” package free LED under operational and humidity...
In this study, the reliability of LED spotlight module with consideration of the contact between a module made of polybutylene terephthalate (PBT) and the aluminum heat sink is investigated by non-linear finite element modeling. The mechanical behavior of the contact interface under high temperature storage was simulated. The force applied on the thermal interface (FTIM) was obtained from the simulation...
A new “heatsink-less” LED based T8 retrofit design is proposed in this study. The lamp consisted of light emitting elements directly attached on a flexible substrate. The substrate is mount on to the inner wall of a full cylindrical glass tube. The design is intended to simplify the lamp construction. However, since the metal-based heat sink is eliminated, the thermal design is a concern. Finite element...
The influence of viscoelastic behavior of polybutylene terephthalate (PBT) on reliability of the thermal contact of a spotlight module is evaluated. The contact between a module and the heat sink is evaluated using non-linear finite element model. The viscoelastic behavior of PBT was obtained under multiple frequencies from single cantilever DMA experiments. The relevant viscoelastic parameters (i...
The influence of viscoelastic behavior of polybutylene terephthalate (PBT) on reliability of the thermal contact of a spotlight module is evaluated. The contact between a module and the heat sink is evaluated using non-linear finite element model. The viscoelastic behavior of PBT was obtained under multiple frequencies from single cantilever DMA experiments. The relevant viscoelastic parameters (i...
A new “heatsink-less” LED based T8 retrofit design is proposed in this study. The lamp consisted of light emitting elements directly attached on a flexible substrate. The substrate is mount on to the inner wall of a full cylindrical glass tube. The design is intended to simplify the lamp construction. However, since the metal-based heat sink is eliminated, the thermal design is a concern. Finite element...
The excellence of energy efficiency and reliability of LED attract the application of outdoor area lighting. The trends toward increase of power density while minimizing the structure, made the heat dissipation design challenging. The thermal performance of a novel streetlight module with embedded heat pipe is investigated in this study. The thermal performance of the new module is compared with a...
LED module with multiple chips on silicon substrate becomes one of the mainstream light engine designs. Compared to conventional discrete LED package, which based on single die, module design with multi LED dies is necessary to fulfill the high luminous requirement for various lighting applications. Fabrication of the silicon based substrate can take the advantages of wafer level processes, which...
Atomistic coarse grained parameters were calculated from a non-equilibrium molecular dynamics simulation of the separation of an epoxy-copper interface. The methodology to determine the interaction energy and the equilibrium distance between the interfacial materials at a minimum energy is established. The traction-displacement relations of the separation under the influence of time taken for atomic...
With rapid development of lighting emitting diode (LED) market, more people are focusing on reliability testing method of LED luminaries system. Based on the previous exploration, to assess the whole system reliability with a fast way, authors propose to divide the system into several subsystems, and then carry out step stress accelerated testing (SSAT) to get failure mechanism and reliability distribution...
Mesoscale parameters, which describe the atomic interactions of the polymer-metal interface at the separation process, are important in the development of a coarse grain model for the interfacial adhesion study. A non-equilibrium molecular dynamics model is established to obtain the traction-displacement relations of the separation of epoxy-copper interfaces. We study three influencing parameters...
With rapid development of lighting emitting diode (LED) market, more people are focusing on reliability testing method of LED luminaries system. However, it is difficult to use traditional reliability testing method for electronic products to assess LED luminaries with high reliability and long life. In this paper, reliability testing methods applied on LED, LED luminaries and other fields are reviewed...
This paper presents our effort to predict the system reliability of Solid State Lighting (SSL) applications. A SSL system is composed of a LED engine with micro-electronic driver(s) that supplies power to the optic design. Knowledge of system level reliability is not only a challenging scientific exercise but it is also crucial for successful adoption of future SSL systems. Currently, the lifetime...
The traction-displacement relations of the epoxy-copper interfaces are studied using an atomistic model. The reaction force of the epoxy layer in response to displacement of the interface is calculated during molecular dynamics simulation. A parametric study in terms of displacement rate and the step size of displacement increment has been performed. The traction-displacement relations are found sensitive...
In this paper, the Copper wirebonding technology is investigated. From a numerical point of view, the wirebonding process is modelled. Experiments on specially designed bondpads are performed in order to verify the models. As such, this leads to a thorough understanding of the wirebonding process, especially the forces that take a role during this process.
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