数字喷墨打印技术给PCB产业带来的机遇与应用

数字喷墨技术已经应用于PCB,并为PCB产业带来新的机遇。文章综述了数字喷墨技术在PCB制造中的应用,包括其主要设备、主要材料和现存的问题。     

电子设备通用故障的检测方法与技术

由各种电子元器件组成单元电路,由许多个单元电路组成具有特定功能的电路系统就是电子设备。当整个系统不能正常工作时,或达不到其主要性能指标时,说明有的单元电路出现了故障,需要我们检测出故障所在。     

真空电子学和微波真空电子器件的发展和技术现状

真空电子学是研究真空中与电子相关的物理现象的学科,主要研究电子的产生和运动、电子与电磁波和物质的相互作用,是各类真空电子器件和粒子加速器等真空电子装置的基础。微波真空电子器件是最重要的真空电子器件,已广泛应用于国防、国民经济和科学研究领域,是军用和民用微波电子系统的核心器件,本文将介绍真空电子学和微波真空电子器件的发展历史,技术现状和应用情况,并对其发展趋势作简要的评述。     

Measuring the External Quantum Efficiency of Two‐Terminal Polymer Tandem Solar Cells

Tandem configurations, in which two cells are stacked and connected in series, offer a viable approach to further increase the power conversion efficiency (PCE) of organic solar cells. To enable the future rational design of new materials it is important to accurately assess the contributions of individual subcells. Such accurate measurement of the external quantum efficiency (EQE) of the subcells of two‐terminal organic or polymer tandem solar cells poses specific challenges, caused by two characteristics of these cells, i.e. a sub‐linear light intensity dependence of the current and a field‐assisted charge collection. These properties necessitate that EQE experiments are carried out under representative illumination conditions and electrical bias to maintain short‐circuit conditions for the addressed subcell. We describe a method to determine the magnitudes of the bias illumination and bias voltage during EQE measurements, based on the behavior of single junction cells and optical modeling. The short‐circuit current densities of the subcells obtained by convolution of the EQE with the AM1.5G solar spectrum are consistent with those obtained from optical modeling and correctly predict the current density–voltage characteristics of the tandem cell under AM1.5G conditions.     

Use of C-SAM acoustical microscopy in package evaluations and failure analysis

Acoustical microscopy is gaining wide acceptance in the microelectronic packaging community. C-mode scanning acoustical microscopy, C-SAM, is widely used in package evaluations and for failure analysis. This paper discusses several specific topics. These include: (1) popcorn cracking in SMDs; (2) an evaluation of solder die attach in power packages; (3) an instance of top of die delamination which resulted in electrical failures; and (4) moisture sensitivity of other surface mount power packages and how it resulted in ball bond degradation during a new product qualification.     

Qualification of plastic encapsulated microcircuits (PEM) for avionicsBased on ``Plastic Encapsulated Microcircuits (PEM) Qualification Testing'''', by J. A. Scalise, which appeared in the Proceedings of the 46th Electronic Components and Technology Conference, Orlando, FL, U.S.A., 28–31 May 1996, pp. 392–397. © 1996 IEEE.

Microcircuit package qualification testing is used to establish the reliability of integrated circuit processes and devices as they relate to part packaging. This paper presents the results of package qualification tests conducted on plastic encapsulated microcircuits (PEMs) and plastic discrete devices (diodes, transistors) used in avionics applications. Highly accelerated stress test (HAST) and temperature cycle (TC) test results, including part failure mechanisms and associated failure rates, are provided. A variety of plastic package styles and integrated circuit functions have been tested. Examples of package styles tested include small outline (SO), plastic leaded chip carrier (PLCC), thin small outline package (TSOP), plastic quad flat package (PQFP) and plastic dual-in-line (PDIP).Manufacturers' devices have been evaluated and various plastic compounds have been compared to determine which provide optimum reliability. The testing showed that package qualification performance of PEMs is affected by type of compound, passivation (including die coat) and die size. HAST failures are caused by moisture penetration of the package while temperature cycle failures result from coefficient of thermal expansion (CTE) mismatch effects.     

Flash memory architecture

Flash memories entered the nonvolatile memory scenario only a few years ago, and now these kind of memories are battling to substitute either EEPROM or EPROM. In fact, their peculiarities are becoming quite interesting in present day applications.In system updating, low power consumption, embedded algorithm for program and erase, high density, low cost packages are some of the items which are making the Flash grow in the nonvolatile memory market share.Some words must be spent in explaining what the market is asking of Flash, which are the main applications for these memories, and how their architecture is arranged.The Flash memory cell behaviour will be described, then the fundamental operations (read, program and erase) are explained and some words are used to introduce the redundancy and device testability concept.     

多普勒效应在安全行车中的应用

将多普勒效应运用于汽车行驶及交通管理上,使汽车具有自动刹车功能,管理上有超速报警功能,从而降低交通事故的发生率。     

Making your own Automatic Test Equipment has never been easier

<正>Using Planet ATE's SOC "all-in-one" pin electronics solutions it is easy to make your own tester, ATE or to modify load boards for more advanced test capabilities.     

Improved Modification of the Closed-Loop-Controlled AC-AC Resonant Converter for Induction Heating

A single-switch parallel resonant converter for induction heating is implemented. The circuit consists of an input LC-filter, a bridge rectifier, and a controlled power switch. The switch operates in soft commutation mode and serves as a high frequency generator. The output power is controlled via the switching frequency. A steady state analysis of the converter operation is presented. A closed-loop circuit model is also presented, and the experimental results are compared with the simulation results.