Papers by Keyword: Electronic Components

Abstract: The development of modern technology in microelectronics and power engineering requires the creation of efficient cooling systems. This is made possible by the use of special fin technology inside the cavity or special heat transfer Ethylene glycol-copper nanofluids to intensify the heat removal from the heat-generating elements. A numerical study of the natural convection of stationary laminar heat transfers in a closed rectangular cavity with a local source of internal volumetric heat generation. For different Rayleigh numbers and different volume fractions of nanoparticles. The system of equations governing the problem was solved numerically by the fluent computer code based on the method of finite volumes. Based on the Boussinesq approximation. Interior and exterior surfaces are maintained at a constant temperature. The study is carried out for Rayleigh numbers ranging from 10⁴ to 10⁶. The effects of different Rayleigh numbers and volume fractions of nanoparticles on natural convection have been studied. The results are presented as isotherms, isocurrents, and local and mean Nusselt numbers. The aim of this study is to see the influence of the thermal Rayleigh number and the volume fraction of the nanoparticles on the rate of heat transfer.

Abstract: Electronic components soldered with tin base alloys are subject to whiskers formations after an operation period, which produced failures by short circuits. The main factors which determine formation of whiskers are soldering alloy characteristics, substrate alloys which is placed on the surface of the PCB boards and not the least the working environment. Soldering alloy has a major influence on germination and growing whiskers process, by its nature and grain form, dimensions and orientation. Given the preliminary research carried out to diminish the formation of these defects, was proposed to realize these soldered joints using new soldering alloys obtained by melt-spinning method, which have a nanocrystalline, quasi-crystalline or even amorphous structure. In this paper are presented some results obtained on following the influence of soldering alloy structure over whiskers germination and growing process, by simulating the operation conditions according to applicable standards. Were obtained soldered joints on copper plates using a commercial soldering alloy as well as soldering alloys base on Sn-Cu-Ga, Sn-Cu-Ni, Sn-Cu-CO families, obtained by melt-spinning method. Soldering was performed using a soldering iron and after this process, the soldered joints were placed in an incubator under controlled temperature and humidity conditions. Performing SEM analyzes on soldered joints subject to the above treatment, was observed that formation and growing of whiskers diminished with decrease of the grain size.

Abstract: Solder paste is mainly used for welding of resistance, capacitance, integrated circuit (IC) and other electronic components in surface mounted technology (SMT) industry, and the performance of solder paste has a significant impact on the reliability of electronic components. In this paper, processing defects, failure cases and mechanism of electronic components caused by solder paste are analyzed systematically. Improper application of solder paste during welding can lead to numerous processing defects including poor wetting, tombstoning, bridging, solder joint crack, solder ball spattering, corrosion and so on. Finally, an evaluation method of material compatibility is described in this paper, which provides a reference for ensuring the quality of electronic process material and improving the reliability of SMT products.

Abstract: Because of high cooling efficiency, simple structure and good reliability, the liquid-box self-circulation evaporative cooling system has broad applications in the field of electronic equipments. By designing and developing a set of Liquid-box self-circulating evaporative cooling system experimental platform for electronic components. We can study the influence of pipe diameter, height of liquid level and thermal conductive pad on the cooling efficiency of the system.

Abstract: To ensure the normal operation of the electronic components, packaging technology is widely used in the production process of semiconductors, such as stand-alone device, LSI, super LSI, etc. This approach makes a lot of wasted components stay intact and reused. This paper uses laser cutting technology to remove material from PCB resin potting material, establishes the mathematical model of electronic potting materials, designs precision CNC laser cutting equipment for removing potting material under different circumstance. Using precision laser cutting technique, the resin potting material of waste PCB circuit can be removed, so as to expose entirely electronic components and all the solder joints. The technology has high economic benefit by ensuring electronic component function intact for reuse and improving the utilization rate of resource.

Abstract: Growing apprehensions of radiological accidents and terroristic attacks have intensified research efforts to find materials with appropriate radiation sensitivity that are carried close to human body, are ubiquitously available and which can be used as fortuitous dosimeters in rapid determination of doses of individuals after radiation exposure. In this respect, thermoluminescence (TL) and optically stimulated luminescence (OSL) of chip cards and electronic components of personal objects have been recently evaluated by researchers in several countries. OSL and TL signal of chip cards is attributed to SiO₂ grains contained in the epoxy layers used for controlling the thixotropic properties whereas the radiation induced signal in electronic components (resistors, resonators, capacitors, ICs, antenna switches, etc.) of personal objects (mobile phones, USB flash drive, MP3 players, etc.) is attributed to the ceramic contents, especially to Al₂O₃ based substrates.

Abstract: Electronic components are the basis of electronic equipment, and their reliability and lifetime have a direct impact on the work efficiency of the whole electric system. In fact, the test data on life characteristic parameters (LCP) of electronic components present random fluctuations because of the existence of some disturbing factors in the process of life test. This will bring great obstacles to the study on the rules of LCP, the reliability and life forecasting of electronic components. In order to solve these problems, this paper proposes a method of the determination of weight coefficients and an improved weighted average algorithm to reveal the rules of LCP. In the improved weighted average algorithm, the latest data is constantly introduced while the oldest data is removed. By an example of contact bounce time on electromagnetic relay, the application verification has been carried out on the above-stated method in the paper. The results show that the method is effective and feasible.

Abstract: Rapid growth in modern technology places greater requirements on electronic products' performance and quality. For a PCB (printed circuit board) assembly of SMT (surface mounting technology) electronic components, restricted by its limited vision in image collection, a high-pixel CCD (charge coupled device) can only screen local images, and they need to be mosaiced, through matching and alignment, into a complete image, which is to be matched and aligned with a standard image then for image analysis. Therefore, image matching and alignment are of crucial importance to both the precision of image mosaic and the quality of SMT components. This paper proposed a sub-pixel based method, by which local images are marked, matched and aligned into a mosaiced image, which is matched and aligned with a standard image. The error analyses of matching and alignment for four common markers, i.e. circle, ellipse, square and rectangle, show that a square or rectangle marker is preferred for SMT electronic components; when the marker's center point serves as alignment point and the marked data are processed by sub-pixel algorithm, the alignment error can be reduced to about 0.2 pixel point, besides the sub-pixel based method can greatly improve precision when noise is fixed.

Abstract: Vibration capability and reliability is necessarily to be considered for electronic components design. In this paper, the vibration characteristics of electronic components were studied using FEM, for example, gridded electron gun. The dynamical mode of girded electron gun was established. Modal frequency and model obtained by simulation shows tendency as tested experiment results, verifying the correctness of the simulation model and method used. The Parameters showed an inherent property of structure, which provided a theoretical basis for production design, the optimization of parameters and the vibration-resistance reliability improvement of microwave tube. In the aspects of electronic components reliability analysis, the variations of production capability parameters under various stress environments can be gained by FEM simulation technology to evaluate environment adaptability and reliability.

Abstract: Without high quality electronic components, it is difficult for good design electronic component to play roles. In the production process of electronic component, quality control eliminate factors that caused unqualified or unsatisfactory effect by monitoring forming process of quality, so to as achieve requirement of quality. Based on introduction of quality control principle, related factor that affect electronic components screening quality was analyzed and an electronic components quality control method was presented. Specific quality control process and quality control keys were also provided. Quality control example of some electronic components screening shows the feasibility of the proposed quality control method.