Development of micro assembly processes for further miniaturization in electronics production

Steady increase of functionality and concurrent reduction of the package size are one of the key driving forces in electronics production. In this paper we will present solutions developed at the institute for the automated assembly of highly miniaturized flip-chips with pitches down to 100 μm. In particular the present and future influences of miniaturization on the main process steps wafer bumping, component placement, reflow soldering and inspection are examined as well as the influences on complementary materials used. Results regarding the achievable yield after assembly and the reliability of the structures will be presented in addition to an analysis of the failure mechanisms.     

Analytical Performance of CE Microchips with Amperometric Detection

Abstract

Miniaturized Total Analysis Systems (µTAS), such as microchip electrophoresis devices are promising tools for analytical purposes. Capillary electrophoresis (CE) microchips made of various materials, e.g., poly(methylmethacrylate) (PMMA). Topas (thermoplastic olefin polymer of amorphous structure), and glass have been evaluated in this work. An electrochemical detection that combines adequately with these polymeric and glass microchips has been employed. The performance of amperometric detectors based on an end‐channel configuration was tested. Thus, integration and alignment of gold/platinum wire and thick‐film (screen‐printed carbon electrodes) working electrodes was studied. In order to verify the correct alignment of the end‐channel metal‐wire detector, a gold‐based dual electrode detector was also employed. The dual detector was based on a gold film within the separation channel and a gold wire at the end of the channel. The microchip pretreatment, which can affect the charge on the channel surface and electroosmotic flow (EOF), has been discussed, as well as the separation and injection performance.     

Large area rolling of functional metallic micro structures

The reliable fabrication of functional surface structures has become an important factor in modern production processes. With regard to the field of large area micro patterning, particular applications demand for economical manufacturing processes to gain advantageous surfaces. The process-integrated rolling of these structures is a promising approach if suitable roll geometries can be manufactured. This paper focuses on the large area rolling of so called riblet structures. Both experimental test series and related numerical forming simulations are taken into account. Furthermore, demands and potentials from the roll manufacturing point of view are highlighted. Above all, the feasibility of a new winding concept for the continuous patterning of rolls with small negative riblet structures is pointed out. By this means, challenging requirements in connection with riblet rolls—the realization of finest structures with sharp ground radii—can be matched.     

半导体激光器系统设计

介绍一种半导体激光器的设计方法,即采用littrow结构激光头、双层温控、精密恒温、PDH压缩线宽来进行总体设计,并详细地给出了激光头littrow结构的设计与加工细节,得出电流、温度精密可调可控的小型化半导体激光器装置。     

Dendritic heat convection on a disc

In this paper we develop the optimal tree-shaped flow paths for cooling a disc-shaped body by convection. Heat is generated uniformly over the disc area. The coolant enters through the center of the disc, and exits through ports positioned equidistantly along the perimeter. The unknown is the flow architecture. The constraints are the disc size and the total volume occupied by the ducts. It is assumed that the ducts are narrow enough so that the flow is hydrodynamically and thermally fully developed. The ultimate goal is to determine flow architectures that reach simultaneously two objectives: (i) minimal global fluid flow resistance (or pumping power), and (ii) minimal global thermal resistance. When the architecture is optimized for (i), the result is a dendritic structure in which every geometric feature is uniquely determined. The corresponding thermal resistance decreases as the total mass flow rate and the pumping power increase. When the objective is (ii), the optimal architecture has radial ducts, not dendrites. The corresponding fluid-flow resistance increases as the flow rate increases and the global thermal resistance decreases. Put together, these geometric results show that methods (i) and (ii) lead to nearly the same combined performance (thermal and fluid). Examined more closely, the dendrites produced by method (i) perform progressively better as the length scales become smaller. Optimized increasing complexity is the route to high thermal and fluid-flow performance in the limit of decreasing scales.     

现场快速色谱分离检测毒害气体的研究与讨论

传统的对毒害气体的快速现场分析或报警器材具有快速响应、灵敏度高等优点,但是由于缺乏分离手段,不同程度存在抗干扰方面的问题。将快速气相色谱应用于现场快速分析检测,在国外已经屡见不鲜。色谱突出的分离特点使分析的准确性大大增加。本文以现场分离毒害气体为应用点,介绍了适合于现场快速分离检测的色谱仪器和装置、微型柱,关键因素如进样方法、检测器、载气等方面进行了详细分析。     

Experimental investigation on a membrane distillation based micro-separator

In this work a novel micro-separator combining the sweep gas membrane distillation principle with micro-fluidic channels was designed and tested for the separation of a mixture of methanol and water with a low to high methanol concentration. The performance of the new separation device was studied with different liquid–vapor/gas membrane contactors with respect to the separation factor and the distillate flux rate by varying the relevant operating parameters of the process like the methanol concentration in the feed (5–70 wt.%), the feed temperature (40–65 °C), the feed flow rate (up to 30 ml/min), and the flow rate of the inert carrier gas nitrogen (up to 600 ml/min at standard conditions). For all performed experiments, the feasibility of the separation has been proved and the possibility to separate mixtures with high methanol concentration by using a membrane distillation based micro-separator has been for the first time reported. The inert gas flow rate was identified as the crucial operating parameter influencing the separation performance of the micro-separator. In addition, the selection of an appropriate membrane liquid–vapor/gas contactor was found to be an important design parameter for the reduction of temperature polarization effects.     

CNC microturning: an application to miniaturization

Micromachining is the basic technology of microengineering for the production of miniature components. One group of tool based micromachining technology is CNC microturning. It is a conventional material removal process that has been miniaturized. The objective of this study is to asses the machinability of brass, aluminium alloy and stainless steel during external cylindrical longitudinal microturning process for different workpiece–tool combinations. Experiments were carried out by varying the depth of cut, feed rate and spindle speed. One parameter was varied while the other two were kept constant in order to identify the best combination of cutting parameters. Machinability assessment was done by force analysis, chip analysis and tool wear criterion. Microshafts were fabricated with brass, aluminium alloy and stainless steel. Finally, microturning process was successfully applied to fabricate compound shaped micropins of diameter less than 0.5 mm.     

Study on Nano EDM Using Capacity Coupled Pulse Generator

This paper describes the development of a pulse generator for nano EDM using a capacity coupling method. To obtain discharge craters of nanometer diameter, a pulse generator was coupled to the tool electrode by a capacitor. Since the influence of the stray capacitance in the electric feeders can be eliminated, the discharge energy can be minimized to accomplish nano EDM. This method also allows non-contact feeding of electric current to the rotating spindle, minimizing the run-out of the tool electrode. To control the gap width, the gap voltage was also measured using the capacity coupling method.     

光纤双波长数字式测温仪系统研究

本文系统地介绍了一种双波长光纤测温仪的原理、结构及特点,其突出优点有：采用双波长窄带比较技术和以微控制器,可编程外围芯片为核心,构成数字化、小型化光纤传感系统,抗干扰能力强,具有通信接口,可与过程控制网络连接,支持流行的现场总线协