集成电路内部水汽含量的控制

简要叙述了集成电路封装内部水汽的形成；指出集成电路封装内部水汽主要是由封装环境气氛中的水份以及封装管壳和芯片表面吸附的水汽所造成的；论述了内部水汽引起集成电路电性能的退化，从而影响建成电路的可靠性。并介绍了纯氮气气氛保护封装、增加红外烘烤等控制集成电路内部水汽含量的措施。     

陶瓷封装电路内部水汽的稳定性控制

简述了集成电路陶瓷封装内部水汽含量的不稳定性,主要是由粘接材料导电胶在高温下分解释放出的水汽所造成的.不同的封装温度内部水汽含量不一样.说明导电胶应充分固化,尽可能在较低的温度下进行封盖.     

半导体集成电路封装用环氧树导电胶概论

简要叙述用于半导体集成电路封装芯片粘接用材料---环氧树脂导电胶组成成分、特性,重点介绍了环氧树脂导电胶在使用过程中要考虑的因素。     

氰酸酯／BMI／环氧树脂共混体系在IC封装基板材料中的应用

文章介绍了采用氰酸酯树脂、双马来酰亚胺、环氧树脂共混体系研制一种用于IC封装基板领域的高性能覆铜板。所研制的覆铜板与环氧树脂体系覆铜板相比,具有高Tg、低介电常数、低CTE的性能。     

导电胶固化状态对器件内部水汽含量的影响

气密性封装器件的芯腔内部如果存在大量的水汽，则会影响器件的可靠性，因此在封装的过程中，要对器件内部的水汽含量进行控制。但是目前的控制措施主要是从封帽环境、原材料等方面入手，对导电胶固化状态对器件内部水汽含量的影响研究得较少。因此，首先，对比了不同固化状态导电胶的固化度和吸水率；然后，对不同固化状态对器件内部水汽含量的影响进行了研究。结果表明，充氮烘箱的装载量会影响导电胶的固化状态。当导电胶在300℃下的固化时间为30 min时，其固化度为100%，吸水率约为0.45%；当在300℃下的固化时间为10 min时，其固化度约为92%，吸水率约为0.94%。导电胶固化不充分时，其在温度循环和高温烘烤中会继续固化，并释放出少量的水汽和大量的二氧化碳。固化不充分的导电胶会在双85试验中吸收水汽，即使器件在封帽前会进行烘烤，吸收的水汽也未能完全排出，导致器件内部水汽含量升高。随着烘烤时间的增加，器件内部水汽含量逐渐地减少，当将烘烤时间延长至13 h时，可有效地去除固化不充分导电胶吸收的水汽，使水汽含量低于1 000×10^-6。     

环氧树脂及其增强材料回顾

本文回顾了PCB制造常用的环氧树脂及其增强材料的性能和用途。同时,还介绍了代用树脂材料和代用增强材料的最新进展,如改性环氧树脂、无卤树脂、Thermount、PTFE、氰酸酯等,并就其性能进行了探讨。     

一种航天用光电耦合器内部气氛含量优化控制

光电耦合器内部气氛含量过高会加速光电耦合器的失效,光电耦合器的寿命与内部气氛含量呈负指数关系,即寿命随内部气氛含量的提高而迅速降低。介绍了光电耦合器内部气氛含量的控制方法,通过优化和改进管壳除氢工艺、(管壳和芯片)清洗工艺、(内瓷片和芯片)烧结工艺、助焊剂清洗工艺、平行封焊工艺,使一种气密性陶瓷封装光电耦合器内部气氛含量得到了优化和控制。     

电子封装用环氧树脂的研究现状与发展趋势

简要介绍了电子封装用环氧树脂材料的特性和组成,论述了其增韧、导热、耐热、阻燃和降低内应力等方面的研究状况,对新型电子封装用液晶环氧树脂、脂环式环氧树脂、纳米改性环境树脂、绿色封装材料及面向系统封装的高分子材料改性技术进行了探讨。     

聚醚改性环氧树脂对导电胶的影响

将聚醚多元醇与多聚磷酸反应生成聚醚多元醇磷酸酯,再与双酚A环氧树脂反应制得聚醚多元醇磷酸酯改性环氧树脂,并通过红外光谱和固化物断面形貌观察证明增韧改性成功。将双酚A环氧树脂和聚醚改性环氧树脂按不同比例混合,并添加相同成分相同比例的助剂、银粉制成导电胶,对比测试导电胶的体积电阻率、热导率、剪切强度、硬度等性能参数,发现随着聚醚改性环氧树脂占比的增加,导电胶的导电导热性能不断提升,体积电阻率最低达到1.9×10^-5Ω·cm,热导率最高可达15.9 W·(m·K)^-1,硬度和剪切强度逐渐降低到67.7 HD和16.8 MPa。观察导电胶断面的微观形貌,发现随着聚醚改性环氧树脂含量的增加,导电胶断口表面光滑平整的树脂逐渐变得粗糙不平,断面银粉由裸露逐渐被树脂包裹。分析认为聚醚改性环氧树脂引入大量柔性基团,降低导电胶硬度与强度的同时提高了固化收缩率,从而提高导电导热性能。在剪切力作用下,裂纹不再沿树脂与银粉之间的界面扩展,而是沿树脂基体内强度较低的柔性基团扩展。     

绿色电子制造及绿色电子封装材料

阐述了绿色电子制造(包括电子封装)概念起源、定义以及基本内涵和范畴,并从电子封装用互连材料、被连接材料和封装后清洗过程这三个方面全面阐述了绿色电子封装的主要内容,重点评述了目前绿色电子封装材料(包括无铅钎料、钎剂、焊膏和导电胶等)的研究现状和面临的问题.最后,展望了绿色电子制造及绿色电子封装材料的未来发展趋势.     

玻璃封帽内部水汽控制技术

重点介绍采用黑瓷低温玻璃陶瓷外壳(CerQFP64)封装的集成电路水汽超标的原因。根据此种外壳的特殊性,通过采用特殊的高温烘烤处理措施,使采用黑瓷低温玻璃陶瓷外壳(尤其对超过保质期的外壳)封装的电路内部水汽由原来的5 000×10-6,降低到2 000×10-6以下。     

Moisture evolution analysis of sealing glasses used in integrated circuit packaging

Free moisture in the cavity of a sealed hermetic integrated circuit is considered an important reliability hazard. The contribution to the cavity moisture by the packaging materials can be studied effectively using the technique of moisture evolution analysis (MEA). The technique involves passing a dry carrier gas over the sample at high temperatures and measuring its moisture uptake coulometrically. The standard moisture evolution technique has been modified to quantify the kinetics of moisture evolution from sealing glasses used for hermetic sealing of I.C. packages which are primary contributors to total cavity moisture. It is also shown that once the moisture evolution mechanisms are understood, the technique of moisture evolution analysis can be correlated to a more complex, industry standard method for free cavity moisture measurement in a sealed hermetic package (RGA-mass spectrometry). MEA can therefore be used for the process control and prediction of free cavity moisture of hermetically sealed I.C. packages.     

PBGA器件潮湿扩散和湿热应力的有限元分析

塑料封装器件暴露在一定的潮湿环境下将会吸收潮湿的现象已经得到广泛的认同。针对实际的PBGA器件,采用通用有限元软件分析和计算了器件在潮湿环境下的潮湿扩散。并且计算了由于吸潮使器件在高温下产生的湿热应力。有限元模拟计算表明,不同潮湿环境下器件的潮湿扩散状态是不一样的,这导致在其后的高温焊接过程中器件内部产生的湿热应力的不同。     

Comprehensive Warpage Analysis of Stacked Die MEMS Package in Accelerometer Application

<正>Packaging of MEMS ( micro-electro-mechanical system ) devices poses more challenges than conventional IC packaging, since the performance of the MEMS devices is highly dependent on packaging processes. A Land Grid Array ( LGA ) package is introduced for MEMS technology based linear multi-axis accelerometers. Finite element modeling is conducted to simulate the warpage behavior of the LGA packages. A method to correlate the package warpage to matrix block warpage has been developed. Warpage for both package and sensor substrate are obtained. Warpage predicted by simulation correlates very well with experimental measurements. Based on this validated method, detailed design analysis with different package geometrical variations are carried out to optimize the package design. With the optimized package structure, the packaging effect on accelerometer signal performance is well controlled.     

A method of the measurement of moisture in IC packages using microwaves

A new method to measure the moisture content of integrated circuit (IC) packages is demonstrated. The moisture contained in the encapsulant resin was determined by using microwaves. The microwave signal was transmitted into the encapsulant resin and reflected at the surface of the chip pad. The amplitude and phase of the reflection coefficient of the microwave signal, which varied with the moisture content of the encapsulant resin, were measured in order to determine the moisture content. A preliminary experiment was carried out, and the calibration equation was developed. The present technique indicates the possibility of determining the moisture content directly without drying and weighing IC packages.     

Effects of Different Kinds of Underfills and Temperature–Humidity Treatments on Drop Reliability of Board-Level Packages

The hygrothermal and mechanical reliability of board-level packages with various underfills under sequential temperature and humidity (TH) testing and drop testing were investigated. Board-level packages with underfill had greater resistance to drop shock than that without underfill, indicating that underfill protects the package from failure by absorption of the applied drop shock. The underfill, which was composed of polypropylene glycol epoxy resin and silane, exhibited good reliability for drop shock because of the improved adhesion of the underfill compared with that without the polypropylene glycol epoxy resin and silane. In addition, the drop reliability of board-level packages with underfill decreased with increasing TH test duration. Adhesion between the substrate and underfill or between the solder and underfill was decreased by moisture absorption. Components positioned at the board center were more susceptible to failure by drop shock than were corner components.     

High density packaging technology ultra thin package & new tab package

As electronic devices become more highly integrated, the demand for small, high pin count packages has been increasing. We have developed two new types of IC packages in response to this demand. One is an ultra thin small outline package (TSOP) which has been reduced in size from the standard SOP and the other, which uses Tape Automated Bonding (TAB) technology, is a super thin, high pin count TAB in cap (T.I.C.) package. In this paper, we present these packages and their features along with the technologies used to improve package reliability and TAB. Thin packages are vulnerable to high humidity exposure, especially after heat shock.1 The following items were therefore investigated in order to improve humidity resistance: (1) The molding compound thermal stress, (2) Water absorption into the molding compound and its effect on package cracking during solder dipping, (3) Chip attach pad area and its affect on package cracking, (4) Adhesion between molding resin and chip attach pad and its affect on humidity resistance. With the improvements made as a result of these investigations, the reliability of the new thin packages is similar to that of the standard thicker plastic packages.     

用于LED封装的等离子清洗设备选型及工艺优化

等离子清洗工艺具有效果明显、操作简单的优点,在电子封装(包括半导体封装、LED封装等)中得到了广泛的应用;基于加工成本考虑,LED封装制程中普遍采用高密度加工方式(整个料盒清洗),清洗效果不理想。本文针对用于LED封装的等离子清洗设备选型、工艺优化进行了探讨,提出了有效的解决方案。     

A novel flip chip technology using nonconductive resin sheet

The process flow of this new packaging system is as follows. First, epoxy base resin sheet is laminated onto substrate to cover the substrate surface including land electrodes. Bumped chip alignment and attachment was done through the resin sheet, in the second stage with pressure and temperature. The bumps under the chip penetrate with removal of resin sheet material eventually reaching to the metal land of the substrate in this process. Metal connection and curing of the interface resin have been completed in the third stage. This new process has the potential to make flip chip packages simple compared with the current process using liquid resin with dispensing system. The throughput time can be reduced to less than 10 s/unit in actual model case even for large flip chip package which has over 15×15 (mm) square area IC chips. The other advantages are thermal stability of material in the process, moisture related performance, and warpage control performance. For current underfill process the only choice is to use anhydride type resin system which has many disadvantages. This new process made it possible to introduce moisture and thermally stable epoxy resin with phenol curing system for flip chip packaging. Drastic process ability improvement can be achieved by the new process and material. As a typical improvement of thermal shock performance, it was confirmed that the life of chip damage is over 10 times longer by flip chip bonding parameters which can be controlled only by this new flip chip packaging process     

PBGA封装的可靠性研究综述

通过传统BT类型的PWB材料与独特的PWB材料来PBGA封装的可靠性。相关的研究结果表明,后者同样具有相同的热循环稳定性和回流焊期间的疲劳强度,并具有较低的封装翘曲特点;模塑料的低吸湿性及粘片材料的高粘附强度和高断裂强度特性,有利于提高回流焊期间的疲劳强度和防止剥离现象的扩散。