1,721,625 research outputs found
Adhesion strength of leadframe/EMC interfaces
No full textCu-based leadframe sheets were oxidized in alkaline solutions to produce brown and/or black oxide on the surfaces, and molded with epoxy molding compound (EMC). The adhesion strength of leadframe/EMC interface was measured using sandwiched double-cantilever beam (SDCB) specimens and pull-out specimens. Results showed that the adhesion strength of leadframe/EMC interface was inherently very poor but could be increased drastically with the nucleation of acicular CuO precipitates. The presence of smooth-faceted Cu(2)O on the surface of the leadframe gave close to zero fracture toughness (G(C)) and suitable pull strength (PS). A direct correlation between G(C) and PS showed that PS can be a measure of G(C) only in a limited range
Effects of chemical oxidations on the fracture toughness of leadframe/EMC interfaces
No full textCu-based leadframe sheets were oxidized by a chemical oxidation method, which formed two kinds of oxides on its surface, a brown one and a black one. The oxidation characteristics of each oxide were studied and then to measure the adhesion strength of the leadframe/EMC interface as a function of fracture toughness, the oxidized leadframe samples were molded with an epoxy molding compound (EMC) and machined to form sandwiched double-cantilever beam (SDCB) specimens. SEM and XRD studies on the surfaces of the oxidized leadframe as well as the measurement of fracture toughness showed that the interfacial fracture toughness is directly related to the formation of acicular CuO precipitates on the surface of the leadframe. However, once a continuous layer of CuO precipitates formed on the surface of the leadframe (brown oxide) or on the Cu2O layer (black oxide), the interfacial fracture toughness is found to saturate regardless of a further oxide thickening. The size of the acicular precipitates seems to have a secondary effect on the interfacial Fracture toughness
Balanced binary-tree decomposition for area-efficient pipelined FFT processing
No full textThis paper presents an area-efficient algorithm for the pipelined processing of fast Fourier transform (FFT). The proposed algorithm is to decompose a discrete Fourier transform (DFT) into two balanced sub-DFTs in order to minimize the total number of twiddle factors to be stored into tables. The radix in the proposed decomposition is adaptively changed according to the remaining transform length to make the transform lengths of sub-DFTs resulting from the decomposition as close as possible. An 8192-point pipelined FFT processor designed for digital video broadcasting-terrestrial (DVB-T) systems saves 33% of general multipliers and 23% of the total size of twiddle factor tables compared to a conventional pipelined FFT processor based on the radix-2(2) algorithm. In addition to the decomposition, several implementation techniques are proposed to reduce area, such as a simple index generator of twiddle factor and add/subtract units combined with the two's complement operation.This work
was supported by Institute of Information Technology Assessment through
the ITRC and by IC Design Education Center (IDEC
Scheduling single-armed cluster tools with reentrant wafer flows
No full textA cluster tool for semiconductor manufacturing consists of several single-wafer processing chambers and a wafer-handling robot in a closed environment. The use of cluster tools is extended to reentrant processes such as atomic layer deposition, where a wafer visits a processing chamber more than once. Such a reentrant wafer flow complicates scheduling and control of the cluster tool and often causes deadlocks. We examine the scheduling problem for a single-armed cluster tool with various reentrant wafer flows. We develop a convenient method of modeling tool operational behavior with reentrant wafer flows using Petri nets. By examining the net model, we then develop a necessary and sufficient condition for preventing a deadlock. We also show that the cycle time for the asymmetric choice Petri net model for a reentrant wafer flow can be easily computed by using the equivalent event graph model. From the results, we systematically develop a mixed integer programming model for determining the optimal tool operation sequence, schedule, and cycle time. We also extend a workload measure for cluster tools with reentrant wafer flows. Finally, we discuss how our results can be used for engineering a cluster tool. We compare two proposed strategies, sharing and dedicating, of operating the parallel processing chambers for identical process steps.The Brain Korea 21 Fun
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