along with same bond pad, copper will introduce hardness The characterization of inter-metallic coverage and inter-related issues, because copper is relatively harder than gold metallic phase's (IMPHs) growth in gold ball bonds on material. When we use the same wire bonder and apply aluminum bond pads are quite well understood and there is similar fundamental process parameters, copper will lead to relatively a very less literature available regarding the problems like crater, etc. The fact is copper strain hardens morphology and growth of the IMPHs and remnant aluminum even during bonding and makes it more difficult to bond on mo~~~~~~~~~~~~~nsrfae Evegy n grwe modi the bon pa, problremsan likeum requirement in copper ball bonds on aluminum bond pad any surface Even we modify the bond pad, problems like metallization. Development and optimization of robust copper oxidation observed in the free air ball (FAB) formation occurs.wire bonding processes are very popular now a days and it Steps have been taken to rectify the oxidation problem, by requires an assessment of remnant aluminum, inter-metallic providing a shield gas (forming gas: 95% N2 and 500 H2) coveage*ndoppe-aluinu inigroh aer, bond pad metallization and bonding parameters are optimized coverage and copper-aluminum inter-metallic growth after isothermal aging under the condition of with and without to avoid the pad peeling and oxidation issues. At this point epoxy molding stages. The assessment of the remnant perfect bond ability is achieved by the wire bonders using the Aluminum and inter-metallic compound formation between suitable forming gas kit and parameters. copper-aluminum is very important in microelectronicOn completion, the wire bonded unit will undergo packaging units. Because the reliability (interfacial shear reliability checking. This is crucial for any IC device force, open failure etc.) of copper ball onto the aluminum packages. Reliability is important for the copper wire bonded based bond pad in microelectronics packaging depends on the unit under different (JEDEC levels) reliability test conditions. remnant aluminum and Cu-Al inter-metallic's formation. This To pass the reliability test, a sufficient amount of remnant study reports a minimum requirement of remnant aluminum Aluminum is necessary in the bonded unit. The remant needed in the copper wire bonding on aluminum pad that were aluminum depends on the bonding parameter, EFO parameters subjected to annealing for long intervals of time from 0 to 300 (firing time, current), purity of Cu wire (3N, 4N, 5N) and hrs using different purity wires (3N and sN). This study gives bond pad compositions (Si, Cu etc). In wire bonder, we can information about how much Aluminum pad thickness is vary the bonding and EFO parameters to achieve the needed for any purity of copper wire bonding and how long optimized bond parameter. When we change the wire type, we the interfacial shear force will increase/decrease with the would not know, what will happen in the material between baking time and also ...
In this study, the microstructure and mechanical property of Al/Cu clad material fabricated by differential speed rolling at room temperature were evaluated. Al and Cu plates were prepared and mechanically cladded at a differential speed ratio of 2:1 between the upper and lower rolls. Post- heat-treatment was carried out after the mechanical cladding at 400 °C for 60 min to induce the formation of intermetallic compound layers at the bonded interface of Al/Cu. As a result, differential speed rolling afforded a soundly cladded interface without any defects such as voids and cracks. In addition, intermetallic compound layers such as Al4Cu9 and Al2Cu were formed at the mechanically bonded interface during post-heat-treatment for 60 min, which led to an increase in Vickers microhardness value more than 30% relative to the base material. Therefore, we systematically explained the relationship between formation of intermetallic compounds and mechanical property of Al/Cu clad materials in this study.
This study was carried out to evaluate the microstructures and mechanical properties of a friction stir welded Ni based alloy. Inconel 600 (single phase type) alloy was selected as an experimental material. For this material, friction stir welding (FSW) was performed at a constant tool rotation speed of 400 rpm and a welding speed of 150~200 mm/min by a FSW machine, and argon shielding gas was utilized to prevent surface oxidation of the weld material. At all conditions, sound friction stir welds without any weld defects were obtained. The electron back-scattered diffraction (EBSD) method was used to analyze the grain boundary character distributions (GBCDs) of the welds. As a result, dynamic recrystallization was observed at all conditions. In addition, grain refinement was achieved in the stir zone, gradually accelerating from 19 µm in average grain size of the base material to 5.5 µm (150 mm/min) and 4.1 µm (200 mm/min) in the stir zone with increasing welding speed. Grain refinement also led to enhancement of the mechanical properties: the 200 mm/min friction stir welded zone showed 25% higher microhardness and 15% higher tensile strength relative to the base material.
The demand of crack tip opening displacement (CTOD) test which evaluates fracture toughness of a cracked material is very important to ensure the stability of structure under severe service environment. The validity of the CTOD test result is judged using several criterions of the specification standards. One of them is the artificially generated fatigue pre-crack length inside the specimen. For acceptable CTOD test results, fatigue pre-crack must have a reasonable sharp crack front. The propagation of fatigue crack started from the tip of the machined notch, which might have propagated irregularly due to residual stress field. To overcome this problem, test codes suggest local compression method, reversed bending method and stepwise high-R ratio method to reduce the disparity of residual stress distribution inside the specimen. In this paper, the relation between the degree of local compression and distribution of welding residual stress has been analyzed by finite element analyses in order to determine the amount of effective local compression of the test piece. Analysis results show that initial welding residual stress is dramatically varied three-dimensionally while cutting, notch machining and local compressing due to the change of internal restraint force. From the simulation result, the authors find that there is an optimum amount of local compression to modify regularly for generating fatigue pre-crack propagation. In the case of 0.5% compressions of the model width is the most effective for uniforming residual stress distribution.
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