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The oxide formation on thin copper films deposited on Si wafer was studied by XPS, SEM and Sequential Electrochemical Reduction Analysis SERA. The surfaces were oxidized in air with a reflow oven as used in electronic assembly at temperatures of 100 °C, 155 °C, 200 °C, 230 °C and 260 °C. The SERA analyses detected only the formation of Cu2O but the XPS analysis done for the calibration of the SERA equipment proved also the presence of a CuO layer smaller than 2 nm above the Cu2O oxide. The oxide growth follows a power-law dependence on time within this temperature range and an activation energy of 33.1 kJ/mol was obtained. The wettability of these surfaces was also determined by measuring the contact angle between solder and copper substrate after the soldering process. A correlation between oxide thickness and wetting angle was established. It was found that the wetting is acceptable only when the oxide thickness is smaller than 16 nm. An activation energy of 27 kJ/mol was acquired for the spreading of lead free solder on oxidized copper surfaces.From wetting tests on copper surfaces protected by Organic Solderability Preservatives (OSP), it was possible to calculate the activation energy for the thermal decomposition of these protective layers. 相似文献
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K. Kords A.E. Pap G. Tth M. Pudas J. Jskelinen A. Uusimki J. Vhkangas 《Optics and Lasers in Engineering》2006,44(2):112-121
A novel process for laser soldering of flip-chips on transparent printed circuit board assemblies is presented. The experiments were carried out on silver test patterns printed on glass wafers using a roller-type gravure offset printing method. The contact pads, where the bumps of the flip-chips are positioned, were covered with a thin layer of additional solder paste. The aligned samples (solder pad—solder paste—chip bump) were illuminated through the glass substrate using an Ar+ laser beam (, , at 1/e) to heat the printed pad and melt the solder paste, thus forming a joint between the printed pad and the chip bump. The heat-affected zone was modeled using computer-assisted finite element method. The solder joint cross-sections were analyzed using optical and electron microscopy as well as energy dispersive X-ray element analyses. The laser-soldered joints were of good mechanical and electrical quality and the process proved to be suitable for manufacturing customized circuit prototypes. 相似文献
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The vibration characteristics of an aluminum surface subjected to ultrasonic waves were investigated with a combination of numerical simulation and experimental testing. The wetting behavior of solder droplets on the vibrating aluminum surface was also examined. The results show that the vibration pattern of the aluminum surface is inhomogeneous. The amplitude of the aluminum surface exceeds the excitation amplitude in some zones, while the amplitude decreases nearly to zero in other zones. The distribution of the zero-amplitude zones is much less dependent on the strength of the vibration than on the location of the vibration source. The surface of the liquid solder vibrates at an ultrasonic frequency that is higher than the vibration source, and the amplitude of the liquid solder is almost twice that of the aluminum surface. The vibration of the surface of the base metal (liquid solder) correlates with the oxide film removal effect. Significant removal of the oxide film can be achieved within 2 s when the amplitude of the aluminum surface is higher than 5.4 μm or when the amplitude of the liquid solder surface is higher than 10.2 μm. 相似文献
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Lin Li 《Optics and Lasers in Engineering》2000,34(4-6):231-253
This paper presents a review of the direct applications of high-power diode lasers for materials processing including soldering, surface modification (hardening, cladding, glazing and wetting modifications), welding, scribing, sheet metal bending, marking, engraving, paint stripping, powder sintering, synthesis, brazing and machining. The specific advantages and disadvantages of diode laser materials processing are compared with CO2, Nd:YAG and excimer lasers. An effort is made to identify the fundamental differences in their beam/material interaction characteristics and materials behaviour. Also an appraisal of the future prospects of the high-power diode lasers for materials processing is given. 相似文献
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Silver oxalate Ag2C2O4, was already proposed for soldering applications, due to the formation when it is decomposed by a heat treatment, of highly sinterable silver nanoparticles. When slowly decomposed at low temperature (125 °C), the oxalate leads however to silver nanoparticles isolated from each other. As soon as these nanoparticles are formed, the magnetic susceptibility at room temperature increases from −3.14 10−7 emu.Oe−1.g−1 (silver oxalate) up to −1.92 10−7 emu.Oe−1.g−1 (metallic silver). At the end of the oxalate decomposition, the conventional diamagnetic behaviour of bulk silver, is observed from room temperature to 80 K. A diamagnetic-paramagnetic transition is however revealed below 80 K leading at 2 K, to silver nanoparticles with a positive magnetic susceptibility. This original behaviour, compared to the one of bulk silver, can be ascribed to the nanometric size of the metallic particles. 相似文献
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Lanin VL 《Ultrasonics sonochemistry》2001,8(4):379-385
Ultrasonic (US) soldering of electronic components, as an alternative to flux soldering, is environmentally friendly, improves the quality of soldered connections at the mounting elements after long-term storage, and allows the use of lead-free solders. Methods of US solder melt activation, lead-free solders in US soldering and glass-ceramic capacitor metallization processes have been investigated. 相似文献
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