应用于裸芯片去污的气相清洗技术

军用和民用微型电子产品的MCM、HIC等复杂混合电路正在越来越多地采用裸芯片,然而,裸芯片由于尺寸小、电路密集、焊盘间距小等原因,在进行组装的过程中一旦有微量的污染物出现,就会对裸芯片的应用造成较大影响。气相清洗通过清洗溶剂蒸汽在组件表面冷凝,形成液体滴下带走污染物,避免了传统的通过机械力、超声振动等清洗方式对裸芯片造成的不可修复的损伤。对限幅二极管砷化镓裸芯片、硅基裸芯片进行气相清洗,有效除去裸芯片表面的污染物,具有无损高效的特点。

Microstructure and Mechanical Property of Al-Cu-Li Alloy Joint by Laser Welding with Filler Wire

The Al-Cu-Li alloy is welded by using laser beam welding,and the welding wire ER4043 is used as filler metal. The microstructure and mechanical property of welded joints are systematically investigated. Microstructure analyses show that the fusion zone is mainly composed of α-Al matrix phase and some strengthening phases including T,δ’,θ’,β’ and T1,etc. During welding,the weld formation and joint quality are obviously improved by the addition of Al-Si filler wire. The measurements of mechanical property indicate that,compared with that of the base metal(BM), the microhardness in the weld zone is decreased to a certain extent. Under the appropriate welding parameters,the tensile strength of welded joint reaches 369.4 MPa,which is 67.8% of that of the BM. There are many dimples on the joint fracture surface,and it mainly presents the fracture characteristic of dimple aggregation.

Microstructures and mechanical properties of a martensitic steel welded with flux-cored wires

This study was focused on wear-resistant material prepared by CO2 GMAW method to basically determine the alloys and hardfacing technology which could be employed into mining equipment. Three flux-cored wires with different chemical compositions, marked by DM-I, DM-II and DM-III were used in welding a martensitic steel for the comparison of the microstructures and mechanical properties of the welding metals and HAZ. The results show that DM-I weld metal contains martensite plus other reinforced phases, while both DM-II and DM-III alloys lead to mainly martensitic microstructures with little precipitates. Among all of the tested materials the DM-I alloy has the highest hardness and wear resistance but the lowest impact toughness among the experimental weld metals. Meanwhile, the hardness, impact toughness and wear resistance of the DM-II and DM-III alloys are close to those of the base metal but the DM-III is not as strong as DM-II. Dimples can be found on the impact fracture of the weld metals, but the steel fracture consists of both cleavage and dimples. Thus HAZ has less risk for cracking than the welds, and the DM-II wire which produces the weld having identical mechanical properties to the base metal is suitable for further application.

Preparation,microstructure and degradation behavior of Mg−2Zn−0.4Sc−0.2Zr alloy wire

A biodegradable Mg−2Zn−0.4Sc−0.2Zr(ZK20−0.4Sc)alloy wire with a diameter of 0.5 mm was prepared by a combination of hot extrusion and cold-drawing.The average grain size of ZK20−0.4Sc alloy wire on the longitudinal section along the drawing direction is approximately 7.3μm.The texture results show relatively strong<1020>and weak<1010>fiber texture components parallel to the drawing direction.The ZK20−0.4Sc alloy wire exhibits better mechanical properties with the tensile strength,yield strength and elongate of(329±2)MPa,(287±2)MPa and(14.2±0.5)%,respectively.The better mechanical properties are mainly attributed to the grain refinement strengthening,dislocation strengthening and precipitation strengthening.With the immersion time increasing to 14 d,the corrosion type transfers from filament corrosion and pitting corrosion to severe localized corrosion.