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This paper discusses challenges for multi-scale Finite Element (FE) modeling in microelectronics. Its miniaturization and multi-scale nature is an enabler for in Healthcare and Well-being markets. Function integration and miniaturization enable microelectronic products having functionalities such as rollable display (Figure 1), wireless connectivity & GPS, beaming, illumination systems, body health...
Modelling of MEMS is one of the difficulties faced in advancing the design. The parameters fed to the simulator consist of the material properties and the geometry of the structure. Material wise, researchers are working on developing precise characterisation techniques to ameliorate the mechanical definition of structural material used. More work is now ongoing to ameliorate the fabrication process...
An enhanced smart flow sensor is being developed at IMTEK in order to measure both flow and thermal properties of fluids at the same time. To be able to measure the thermal properties of a fluid, a sinusoidal voltage is applied at heater. This results in a time-dependent temperature response on a thermistor array. Amplitudes of the temperature signals on the thermistors, and thus the maximum sensitivity...
This paper presents a study of the probabilistic effects that act in addition to deterministic (mechanistic) effects to reduce the thermal cycling durability of ball grid array (BGA) interconnects as the component I/O count increases. The mechanistic drivers include increasing thermal expansion mismatch with increasing package size and increasing stress levels with decreasing solder joint size. The...
This paper is to perform a design optimization of micromachined piezoelectric transducer by maximizing the system exciting sensitivity. The transducer is a membrane-based micromachined transducer with the piezoelectric film to excite the membrane vibrating. In this study, the exciting sensitivity is taken as the optimization objective. Specifically, when fixing the exciting signal, the transducer...
In this paper, a wrist device conception was selected to study the reliability of flexible devices by drop test simulation. In the conception device, all of the components cannot be made flexible immediately. Some of them are still rigid, such as the ball grid array (BGA), the connector, and some other big components like the vibrator. The reliability of the device, where such rigid components are...
Rigid-flexible printed circuit boards (RFPCB) has the advantages of providing not only the flexibility and bendability required by many electronic products, but also the reliability required by the key electronic components. In this study, based on one kind of RFPCB which would be used for a wearable device prototype, the structure optimization was performed by simulations. Through the structural...
In this paper we discuss the influence of solder joint geometry on the lifetime of a flip chip assembly. Geometry variations caused by variations of solder volume, pad configuration, and pad size on the printed circuit board (PCB) were taken into account. Typically these parameters vary due to technological fabrication tolerances. Consequently, the influence of such design aspects on system reliability...
The use of an innovative jet impingement cooling system in a power electronics application is investigated using numerical analysis. The jet impingement system, outlined by Skuriat et al, consists of a series of cells each containing an array of holes. Cooling fluid is forced through the device, forming an array of impingement jets. The jets are arranged in a manner, which induces a high degree of...
A continuum damage model is proposed for Sn3.0Ag0.5Cu solder alloy in pure shear conditions. Experimental tests were performed on specific torsion samples to adjust material parameters of the continuum damage model. The main advantage of this method is to introduce damage process in the mechanical behaviour law of SnAgCu solder. Damage process highly affects the mechanical behaviour of solder alloy...
The bump on flexible lead (BoFL) is a chip-to-substrate interconnect technology which uses flexible structures to accommodate the CTE mismatch between the chip and PCB substrate and consequently should be reliable without underfill. To achieve a high flexibility, the lead-free bump is located on a flexible lead. The flexible lead consists of a copper redistribution layer (RDL) embedded in a polyimide-bridge...
The dynamic response of electro-mechanically actuated micro structures is governed by nonlinear effects which directly influence their performance. To date, most work in the field of micro/nano systems is done experimentally and documented theoretical research consists of nonlinear lumped-mass models as well as continuum mechanics approaches. Existing and codified computational tools for micro-electromechanical...
This paper presents in details the fatigue life prediction models developed for lead-free assemblies in harsh environments during the 3-year European LIFE project GEAMCOS. The approach uses advanced finite element modelling as well as experimental fatigue data. It is also based on a complete material characterisation for a wide range of stress conditions. It focuses on the most critical packages of...
This paper discusses the effect of five process parameters on the generation of post weld stresses in the pigtail fibre optic. The alignment of the fibre optic and the laser in the butterfly module become misaligned during the laser welding process of the sleeve to the ferrule. This is primarily due to post welding stresses in the fibre optic which develop during the cooling process. The mechanical...
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