圆片级封装工艺简介及其最新发展趋势

圆片级封装(Wafer Level Package)是近期快速崛起的创新性先进封装工艺。因其适应消费性电子产品对轻薄短小特性的需求,故而被市场广泛接受和推崇。本文将会介绍WLP的工艺流程和工艺控制,在可靠度上的挑战,和探讨圆片级封装的最新发展趋势。     

Synthesis of ultraviolet curable encapsulating adhesives and their package applications for organic optoelectronic devices

With conventional heating process, ultraviolet (UV) illumination, and microwave irradiation, we have successfully synthesized UV curable encapsulating adhesives with excellent gas barrier capabilities, good adhesive strength, moderate hardness, and high refractive indices. The experimental results manifest that the physical properties of lab-made encapsulating adhesives are highly dependent on their chemical structures and synthetic procedure. We also discover that the encapsulating adhesive prepared by microwave irradiation (i.e. encapsulating adhesive VI-MW) exhibits better adhesive strength and higher gas resistance than those prepared by conventional heating process and UV illumination. Furthermore, encapsulating adhesive VI-MW has also been applied for the package of organic light emitting diodes (OLEDs), flexible OLEDs, and organic solar cells. With encapsulating adhesive VI-MW, the entry of oxygen and moisture in the air into these organic optoelectronic devices has been blocked, therefore enhancing the lifetimes.     

封装体异色问题的分析及其对策

本文主要从5H液、脱模剂、应力改性剂、着色剂以及EMC的角度对环氧模塑料封装体异色原因进行分析，并提出相应的对策。     

Effect of hydrogen gas impurities on the hydrogen dissociation on iron surface

A small addition of oxygen to hydrogen gas is known to mitigate the hydrogen embrittlement (HE) of steels. As atomic hydrogen dissolution in steels is responsible for embrittlement, catalysis of molecular hydrogen dissociation by the steel surface is an essential step in the embrittlement process. The most probable role of oxygen in mitigating HE is to inhibit the reactions between molecular hydrogen and the steel surface. To elucidate the mechanism of such surface reaction of hydrogen with the steel in the presence of oxygen, hydrogen, and oxygen adsorption, dissociation, and coadsorption on the Fe(100) surface were investigated using density functional theory. The results show that traces of O₂ would successfully compete with H₂ for surface adsorption sites due to the grater attractive force acting on the O₂ molecule compared to H₂. The H₂ dissociation would be hindered on iron surfaces with predissociated oxygen. Prompted by the notable results for H₂ + O₂, other practical systems were considered, that is, H₂ + CO and CH₄. Calculations were performed for the CO chemisorption and H₂ dissociation on iron surface with predissociated CO, as well as, CH₄ surface dissociation. The results indicate that CO inhibition of H₂ dissociation proceeds via similar mechanism to O₂ induced inhibition, whereas CH₄ traces in the H₂ gas have no effect on H₂ dissociation. © 2014 Wiley Periodicals, Inc.     

功率VDMOS稳态热阻测试的关键影响因素

热阻值是衡量功率VDMOS器件热性能优劣的重要参数,但在实际的热阻测试过程中,诸如测试电流、延迟时间、壳温控制等因素都会对测试结果造成直接的影响。因此,测试时应当深入理解和分析各种影响因素,依据严格的测试标准灵活的使用测试设备,以达到较高的测试精度和重复性。按照稳态热阻测试的步骤,详细论述了影响其测试结果的关键因素,并提出较为准确的修正方法,设计了针对性试验对其进行了验证。试验表明,该测试方法实现了较为精确的稳态热阻测量,可为功率VDMOS热阻测试标准的制定提供参考和借鉴。     

激光二极管高效铜微通道冷却器设计

 通过对铜微通道冷却器的散热分析，设计出５层结构的模块式铜微通道冷却器。采用常规的线切割工艺加工，散热通道宽大约200μm，深300μm，各层间用真空钎焊的方法组装。该冷却器对于腔长06mm、宽10mm的线阵激光二极管芯片热阻为0.58℃/W。通过面阵激光二极管封装实验证明，该冷却器可用于10％占空比工作的面阵激光二极管封装。     

光网络的分类及应用的协议

根据应用的光通信器件类型,光纤网络可分为光纤链接网、广播和选择网络、波长路由网以及全光分组交换网。一种结合了传输层和数据链路层协议的新型传输协议Zing可用于波长路由网中,Zing主要完成差错控制和流量控制两项功能。波长路由网的路由设计要考虑以下问题:支持异机种网络、波长连续性限制以及信令协议要足够简单。     

荧光粉封装方式对多芯片阵列LED封装效率的影响

针对荧光粉封装的多芯片LED,用Monte Carlo光线追迹的方法仿真光线在蓝光芯片和荧光粉中的传播,并分析了荧光粉封装方式对多芯片阵列LED封装效率的影响.结果表明:随着荧光粉层和芯片之间的距离增大,保型涂覆的LED封装效率先增加后减小,最大封装效率为59%;平面涂覆的LED在芯片间距为0.2mm、荧光粉层和芯片之间的距离为0.28mm时,封装效率为77.183%;荧光粉层的曲率半径对封装效率的影响较小.     

再成形(Re-Balled)焊球阵列封装的焊球强度评估

近年来,许多国家禁止在电子产品中铅的使用,但是一些特定产品拥有豁免权。拥有豁免权的电子产品生产厂商面临含铅元器件供应缺乏的现状,因此生产厂商开始寻求利用焊球再成形技术把焊球阵列封装中的无铅焊球转变为锡铅焊球。焊球再成形技术曾经被用于元器件的回收再利用,但是关于焊球再成形元器件的可靠性信息十分有限。介绍了利用焊球再成形技术使无铅焊球阵列封装转变为锡铅焊球阵列封装。两种焊球去除方法和两种焊球再贴装方法分别用于实现从无铅焊球到锡铅焊球的转变,用以调查再成形工艺对于封装质量的影响。热时效试验以及焊球强度评估用于检测焊球再成形工艺过程。     

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。