用于大功率半导体激光器的Ag-In焊料研究

大功率半导体激光器的封装对焊料选择极其重要,因为焊料导热或导电性差,激光器工作产生的大量热量使焊料焊接失效,激光器也会遭到损坏。为此,文中研究了软焊料In及其保护层Ag作为一种焊料组合,通过真空蒸发镀膜仪蒸发蒸镀Ag-In与Ag-In-Ag-In两种薄膜方式。根据微结构知识及扩散动力学与热动力学相结合讨论了Ag-In焊料产生间隙的原因,通过XRD衍射仪了解到薄膜间界面化合物AgIn2的生成可能导致表面微结构的改变,结果表明Ag层对In层易被氧化的性质起到了保护作用,多层的Ag-In焊料层可抑制大量间隙的产生,提高器件工作可靠性及稳定性。     

吸收剂对激光塑料透射焊接质量影响的研究

本文首先介绍了黑色薄膜的制作;其次讨论了两种吸收剂黑色薄膜和黑漆涂层对激光辐射能量吸收的影响,主要包括两个方面,薄膜厚度对热量吸收的影响和碳黑的含量对热量吸收的影响,研究发现吸收薄膜厚度≥0.09mm就能吸收所有的红外辐射能量;碳黑含量为0.07%是吸收能量的理想值;最后,对使用两种吸收剂的焊接样品质量进行对比,发现黑漆涂层的焊接质量远比黑色薄膜的要好.     

C4技术中多层金属化可靠性研究

本文对C4倒装焊技术所涉及凸点下多层薄膜金属(UBM)的选择、基板金属化(TSM)的选择、焊料凸点制作、焊接及影响C4倒装焊的可靠性因素进行了分析，并通过电镜扫描和电子能谱对凸点下多层薄膜金属进行了定量分析，论述了C4倒装焊技术金属化选择对可靠性的影响。     

SiO2-TiO2溶胶-凝胶薄膜的激光致密化研究

为了研究激光直写技术在薄膜器件成型工艺中的应用,采用波长为1.07μm的连续光纤激光器对SiO2/Si基表面SiO2-TiO2多孔溶胶-凝胶薄膜进行致密化的方法,得到了激光功率密度对薄膜收缩率的影响规律以及热处理温度对薄膜的激光致密化功率密度阈值和厚度变化的影响结果.结果表明,薄膜收缩率随着激光功率密度的增加而增大.薄膜热处理温度越高,激光致密化功率密度阈值越高,达到薄膜致密化极限需要的激光能量越大.激光致密化机制是通过硅衬底吸收激光能量,然后以热传导的形式加热溶胶-凝胶疏松薄膜,实现薄膜致密化.     

脉冲激光改性金属纳米薄膜的等离子体特性

在室温环境下,实验采用Nd\:YAG光纤脉冲激光器辐照银(Ag)、铜(Cu)、铝(Al)三种光滑连续的金属薄膜,制备出了对应的三种金属纳米颗粒薄膜。通过调节激光扫描速率可以实现三种金属纳米颗粒薄膜的局域表面等离子体共振(LSPR)波长和强度的调谐。其中,Ag纳米颗粒薄膜在可见光波段的等离子体吸收峰的波长和强度均表现出较宽的调谐范围,Cu纳米颗粒薄膜在可见光波段的等离子体吸收峰的波长和强度均表现较小的调谐范围,Al纳米颗粒薄膜在紫外光波段的等离子体吸收峰窄而尖锐,且LSPR波长调谐范围也较小。与激光辐照前的三种金属薄膜相比,激光辐照后生成的三种金属纳米颗粒薄膜出现了更强的表面增强拉曼散射信号。有限差分时域仿真模拟出的样品的电场强度分布与实验得到的表面增强拉曼散射结果一致。     

双曲两步模型下金属薄膜的热行为

从双曲两步热传导模型出发,运用数值差分法求解了微尺度条件下热传递问题。利用特征值法对耦合的能量方程解耦,得到一组控制薄膜中的热波传播的特征方程,对特征方程组运用Godunov格式进行离散得到特征方程组的解。通过特征方程和原控制方程之间的关系,得到薄膜的温度响应并运用这种方法求解了薄膜的激光加热问题,揭示了在短脉冲激光加热条件下薄膜中热传递的波特性以及金属薄膜中电子气和晶格温度的非平衡态特征。     

激光驱动飞片加载下基体/薄膜层裂微成形研究

为了满足微成形技术产业化的需求,讨论了一种新的微成形方法—激光驱动飞片加载基体/金属薄膜层裂微成形技术,结合激光辐照效应及波的反射规律阐述了层裂微成形原理;优化了基体/金属薄膜层裂工艺,并且根据能量守恒原理,估算了层裂片的应变率和激光诱导冲击波的峰值压力。结果表明,随着脉冲能量的逐渐增大,工件层裂现象不断明显,直到金属薄膜上最后出现与模板微结构相同的特征结构,但基体始终保持完好,未出现裂纹或变形。通过激光驱动飞片加载基体/金属薄膜实现层裂微成形是可行的。     

激光微型焊接在半导体技术中的应用

本文研究了半导体工艺中常用的薄膜电极与细金属引线的微型焊接。借助扫描电子显微镜对焊接区的金属元素成分作了能谱分析,探讨了焊接区组织形貌特征,实验结果与理论分析完全一致。深入讨论了激光微加工与激光脉冲宽度,脉冲能量的关系,得出了在常用的微加工范围。随着焊接工件尺寸增大,对激光热穿透深度的影响程度前者较后者明显,这对于激光微加工在半导体技术中的应用是有意义的。     

真空共晶设备的改进对共晶焊接质量的影响

共晶焊接质量对芯片的可靠性及寿命影响很大。在这方面,通过改进后的真空共晶设备比改进前更具有优势。分析了真空环境对共晶焊接的影响,在原有设备增加了分子泵的情况下,实现无空洞焊接。对甲酸气体保护下的In焊料焊接进行了分析,并结合实际经验给出合理的工艺曲线,证实了在真空室加入甲酸气体的保护下,可以把In焊料表面的氧化层去除,使焊料在浸润性方面具有明显的优势。     

激光焊接珠宝

在1980年莫斯科电工工艺展览会上，Алькон эквипмент商业公司(经销电子、钟表和珠宝工业设备)演示了一种用激光束煌接金项链的新式仪器。早先用焊料，现在则用激光脉冲(每秒3~8次)焊接由任何金属制成的链环、钟表零件、电话接线插件等。焊接速度每分钟180个链环，即使在显微镜下也难以观察到焊料的痕迹。焊接后不需要清洗和任 何打磨加工。用光束聚焦法调节适合焊接各种金属的温度。     

Robust Absorption in a Four-Layer Dielectric-Metal Structure

This letter predicts that robust absorption will appear in a four-layer dielectric-metal structure, and our experimental results verify this prediction well. The mechanisms are as follows: 1) The four layers form a cavity, and zero phase shift at the interface between the first metallic layer and the second dielectric layer is designed to make the backward light form a destructive interference and minimize the reflection. 2) The slow-light effect near the cutoff frequency in this structure increases the absorptive length many times. 3) It also can be explained as an asymmetric resonator, which satisfies the critical coupling condition. Many applications can be developed from this work, such as ensuring laser welding high quality for infrared transparent optoelectronic components.      

真空平板玻璃激光封接气孔控制研究

为了探究激光焊接真空平板玻璃封接层气孔的产生机理，利用扫描电镜、自带能谱仪、X射线衍射仪和金相显微镜等手段，进行了真空平板玻璃激光侧边封接试验，研究了激光功率和焊接速率对封接层气孔的影响，分析气孔产生的原因。结果表明, 真空平板玻璃封接层出现了数量较多、大小不一、相互不连通的孤立气孔，位于颗粒的交界处，主要是由焊料颗粒间的残余空气引起的; 在焊接速率为2mm/s和离焦量为-2mm的条件下，过低或过高的激光功率都不利于减少封接层的气孔缺陷，激光功率为80W(能量密度为80J/mm2)时，封接层组织形貌好，封接层封接质量佳; 在激光功率为80W和离焦量为-2mm的条件下，较低的焊接速率将有利于减少封接层的气孔缺陷，焊接速率为1mm/s(能量密度为160J/mm2)时，封接层组织形貌好，封接层封接质量佳。此研究可为真空平板玻璃的激光封接制造提供理论依据。     

Nd:YAG薄片激光增益介质封装技术

为了保证Nd:YAG薄片激光器的高功率、高光束质量,需解决薄片增益介质封装后的均匀散热、低波前畸变等关键问题。分析了封装过程中薄片增益介质的热应力,模拟了连接界面无缺陷条件下薄片增益介质的热分布,对封装工艺技术进行改进。优化的封装技术将薄片激光增益介质与微通道冷却器连接在一起,采用超声扫描显微镜、激光干涉仪对薄片激光器的焊接界面与增益介质表面面形进行测试。结果表明:该封装技术实现了直径80 mm的大口径YAG薄片与冷却器焊料层均匀、无空洞的界面连接,同时减小了焊接后薄片的波前畸变,60 mm口径内面形畸变PV值小于1 m,均方根RMS值小于0.15 m。该技术封装的单模块Nd:YAG薄片激光器输出功率达到2.3 kW。     

合金焊料盖板选择与质量控制

在平行缝焊、储能焊、玻璃熔封、激光焊、合金焊料熔封等密封工艺中,合金焊料密封是高可靠密封的优选工艺。文章针对合金焊料密封工艺中常遇到的密封强度、密封内部气氛、焊缝及盖板耐腐蚀、薄形封装易短路等问题,介绍了通过合金焊料盖板的选择,从而控制密封强度、密封内部气氛、耐蚀性能和电性能等的质量。     

Studies on CO2 laser drilling: formation mechanism ofresidual thin materials at the bottom of laser via

Formation mechanism of residual thin materials at the bottom of a microvia processed with CO₂ laser is studied with a bromine (Br)-containing epoxy film designed for sequential build-up printed wiring boards. By observing Br content distribution in a cross section of the epoxy film after laser processing, it is estimated that the film around the via is heated up to 1600 K and that the residual thin film at the bottom of the via is heated up to 2000 K upon laser irradiation. Based on heat transfer simulations for epoxy and copper layer structures, the epoxy film within a 0.1-μm distance from the copper surface is unable to be removed by laser irradiation because the temperature of this region cannot be heated above the decomposition temperature of ≈2500 K due to a large heat flow from the epoxy layer to the copper     

IMC Growth at the Interface of Sn–2.0Ag–2.5Zn Solder Joints with Cu,Ni, and Ni–W Substrates

Growth of intermetallic compounds (IMC) at the interface of Sn–2.0Ag–2.5Zn solder joints with Cu, Ni, and Ni–W substrates have been investigated. For the Cu substrate, a Cu₅Zn₈ IMC layer with Ag₃Sn particles on top was observed at the interface; this acted as a barrier layer preventing further growth of Cu–Sn IMC. For the Ni substrate, a thin Ni₃Sn₄ film was observed between the solder and the Ni layer; the thickness of the film increased slowly and steadily with aging. For the Ni–W substrate, a thin Ni₃Sn₄ film was observed between the solder and Ni–W layer. During the aging process a thin layer of the Ni–W substrate was transformed into a bright layer, and the thickness of bright layer increased with aging.     

Laser soldering for chip-on-glass mounting in flat panel display application

Chip-on-glass (COG) mounting of area array electronic packages was attempted by heating the rear surfrace of a contact pad film deposited on a glass substrate. The pads consisted of an adhesion (i.e., Cr or Ti) and a top coating layer (i.e., Ni or Cu) was heated by an UV laser beam transmitted through the glass substrate. The laser energy absorbed on the pad raised the temperature of a solder ball which was in physical contact with the pad, forming a reflowed solder bump. The effects of the adhesion and top coating layer on the laser reflow soldering were studied by measuring the temperature profile of the ball during the laser heating process. The results were discussed based on the measurement of reflectivity of the adhesion layers. In addition, the microsctructures of solder bumps and their mechanical properties were examined.     

覆Ag层对用于LD封装的In焊料性能的影响

In焊料由于其优越的可塑性以及优良的导电、导热特性,被广泛用于半导体激光器(LD)的封装。但是In焊料遇空气易氧化,尤其在焊接加热的过程中,氧化现象更加明显,因此一般当天制备当天使用。为防止氧化,可以在In焊料表面镀一层Ag或Au作为保护层,因为Ag成本较Au低,可作为首选的保护层。关于In-Ag合金性能的研究已有过相关报道,但关于In-Ag合金的表面形貌及Ag层厚度对内部In的影响的报道还很少。文章通过扫描电子显微镜、XRD对不同样品进行了表面和成分的分析,得到了关于Ag对内部焊料的影响以及不同冷却速率下焊料的表面形貌。     

可用于可穿戴设备的透明非晶硅薄膜太阳能电池的研究

一种可用于可穿戴设备屏幕表面的透明非晶硅薄膜太阳能电池,采用激光刻蚀高密度微纳光通道阵列、TCO薄膜作为透明导电背电极,并减薄I层厚度来提升光线透过率。实验表明随着光刻密度增加或I层厚度的减少,光电转换效率会降低,光线透过率会增加,当I层厚度300nm,光刻孔隙直径30m,阵列间隔55m以内时,可获得50%以上的透过率（最高59%）和2.5%以上的光电转化效率（最高3%）。     

Hybrid organic light-emitting device fabricated with semiconducting polyimide via mixed vapor deposition polymerization

Hybrid organic light-emitting devices (HOLEDs) were fabricated with the active molecularly doped polyimide (AMDPI) thin film as a hole-injecting-transporting layer through the mixed vapor deposition polymerization (VDP) process. As a comparison, the polyimide thin film as a hole-injecting-transporting layer was also prepared for a HOLED via VDP. Both the AMDPI and polyimide thin films were almost optically transparent over the entire visible range because the bandgap energy was /spl sim/2.9 eV. HOLEDs with the AMDPI thin film showed a higher luminance and efficiency than that with the polyimide thin film. In particular, the application of a lithium-aluminum cathode significantly enhanced the luminance and the efficiency of HOLEDs with the AMDPI thin film.