Effect of thin film coating of Au on joint strength in invar-invar packages

The effect of a thin film coating of Au on the joint strength, weld width, and penetration depth in laser welding techniques for Invar-Invar packages is investigated experimentally. It is found that the joint strength, weld width, and penetration depth are strongly dependent on the coating of Au thickness on the Invar material. The welded joints with thick Au coating show narrower weld width, shallower penetration, and hence less joint strength than those of the packages with thin Au coating. The increase in both the thermal conductivity and the vapor volume in the welded joints as the coating of Au thickness increases are the possible mechanisms for the reduction. Detailed knowledge of the effect of thin film coatings of Au on the welded materials, which gives both the highest joint strength and good adhesion, is essential for practical design and fabrication of reliable optoelectronic packaging.     

An overview of laminate materials with enhanced dielectric properties

This report focuses on laminate materials (resins and reinforcements) having potential applications in the manufacture of multi-layer printed wiring boards (PWBs) that are required to efficiently transmit high-speed digital pulses. It is intended to be a primer and a reference for selection of candidate materials for such high-performance PWBs. Included are dielectric and physical properties, and where available chemical composition and/or structure, commercial availability, compatibility with typical PWB processing schemes and approximate relative cost. Recommendations are made as to the most viable candidate materials for this type of PWB application, based on a comparison of electrical and physical properties together with processing and cost considerations. The cyanate ester resin system appears promising. Such a resin may be reinforced with regular E-glass, or the more newly available S-glass, to produce a laminate useful for intermediate performance applications. For more demanding applications the E-glass will have to be replaced by a material of much lower relative permittivity. The expanded-PTFE reinforced laminates fromW. L. Gore appear to be a good choice for these applications. The processing of theGore materials can be expected to deviate from that used with FR-4 type materials, but is likely to be less problematic than laminates comprised of a fluorinated resin. Processing is a key obstacle to the implementation of any of the new materials herein. If implementation is to be successful, programs must be established to develop and optimize processing procedures. Cost will remain an important issue. However, the higher cost of the new materials may be justified in high-end products by the performance they deliver.     

The parylene-aluminum multilayer interconnection system for wafer scale integration and wafer scale hybrid packaging

Polyimides have been considered as interlayer dielectrics for wafer scale integration (WSI) and wafer scale hybrid packaging (WSHP). However, high temperature curing steps for polyimide lead to large stresses in polyimide films. This is due to differing thermal expansion coefficients of the metal conductor, insulator and substrate materials causing yield and reliability problems. Polyimides also require the use of solvents, and tend to outgas during subsequent processing. They tend to absorb moisture with resulting degradation of dielectric constants. Also, the spin on method used to apply and planarize polyimide layers exhibits nonuniformity of thickness on large wafers. In this paper we examine parylene (Poly-p-xylylene) and some of its derivatives as possible interlayer dielectrics due to some of their attractive features. Parylene has a low dielectric constant. It can be vapor deposited at low temperatures and in vacuum. It is also highly resistant to corrosion and is a clear, transparent material with possible use for optical interconnections. This paper studies the reactive ion etching properties for polyimides and parylenes in an oxygen containing plasma under identical conditions. The etching rates of the parylenes and polyimides have been compared. The surface properties of these polymers are examined. Further, the film growth properties of aluminum deposited on the etched surfaces using the ionized cluster beam are investigated.     

Packaging of nanostructured microelectromechanical systems microtriode devices

Combining the world of microelectromechanical systems (MEMS) with that of nano can lead to new devices with unique or advanced functionalities. Carbon nanotubes are fascinating new nanomaterials with many interesting physical, chemical, and electronic properties and potential new applications. We have incorporated nanotubes into the MEMS structure as patterned, cold-cathode field emitters to create on-chip, miniature vacuum tubes of microtriodes that can be useful for high-frequency microwave communications. Proper bonding and assembly processes were essential in providing reliable electrical connections and improved amplification performances.     

Stress relaxation in molding compounds

Stress relaxation tests have heen carried out on an epoxy-based molding compound at temperatures ranging from ambient to 260°C. It is found that horizontal shifting produces coherent master curves which are different for different levels of imposed strain, i.e., the material behavior is nonlinear. The use of constant strain rate tensile test data to augment stress relaxation data in forming the broadest viscoelastic representation of the material is discussed.     

表面安装过程中的缺陷及解决方法

本文介绍了在表面安装过程中出现的一些缺陷，这些缺陷会影响产品的可靠性，使电路性能变差。作者针对这些缺陷，提出了相应的解决方案。     

集成电路技术对通信发展的影响

首先说明晶体管和激光管的发明、微电子集成电路、光电子集成和光子集成不断快速进展的情况。于是，叙述几项重要的信息设备技术：（1）处理器、存贮器、计算机；（2）磁盘、光盘、大容量存储；（3）程控交换系统；（4）光纤固定通信网和无线移动通信网。这些重要应用的发展受到集成电路技术的深刻影响，因而能够以惊人速度持续向前跃进。     

All-solid-state pseudocapacitive micro-supercapacitors from laser-treated polymer derivatives

A simple method utilizing laser writing technology to fabricate all-solid-state micro-supercapacitors was reported. The solid-state micro-supercapacitors based on MnO₂/graphene nanocomposites deliver high volumetric capacitances, promising energy density, good stability and low leakage current.     

Recent progress in biodegradable polymers and nanocomposite-based packaging materials for sustainable environment

Plastic-based materials are frequently used in packaging and can be seen universally in both the developed and developing societies. At present, most of the currently used food packaging materials are nondegradable and are creating serious environmental problems. New technologies are being explored and developed to study the complex interaction between the food packaging materials and food. For example, nanocomposite of cellulose constitutes environmentally friendly packaging, which is easily recycled by combustion and requires low power consumption in production. There are several such biodegradable materials which are available at a low price, have good mechanical properties and allow disposal in the soil. This is advantageous because biological degradation produces only carbon dioxide, water, and inorganic compounds to name a few. It has also been discovered that biodegradable plastics made of such materials can be disposed of together with organic waste. The widespread use of biopolymers in the place of standard plastics would help to reduce the weight of waste. Therefore, biodegradable materials take part in the natural cycle “from nature to nature” and play an important role for environmental sustainability. So, in this article, we briefly summarize the different characteristic of biodegradable polymers being used in food packaging applications.     

全金属化应变不敏感FBG温度传感器特性研究

为了解决传统胶封光纤布拉格光栅(Fiber Bragg Grating,FBG)传感器存在严重胶蠕变和老化问题,提出基于一步超声波焊接的全金属化封装FBG传感器方法,采用有限元分析方法进行传感器的应变不敏感结构设计并制作了该温度传感器进行实验验证。测试结果表明,该方法制作的特定封装形式的FBG传感器对轴向应变不敏感,温度灵敏度达到39.16 pm/ ℃,是封装前裸光栅的4倍,线性度超过0.999,具有较好的重复性,并且温度从20 ℃改变到100 ℃的动态测量响应时间小于30 s。该金属化封装FBG温度传感器的工艺简单,制作周期短,其优异的温度传感特性在高精度、高可靠性传感监测领域具有广泛的应用前景。