• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2375-2378
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• 2003

In manufacture of printed circuit boards, one important issue is precisely to measure the three-dimensional shape of the solder paste silk-screened prior to direct surface mounting of chips. This paper presents the 3D shape reconstruction of solder paste using the optical triangulation method based on structured light or slit beam and the measurement algorithm for height, volume. area, and coplanarity on component pads from the 3D range image. Futhermore, statistical process control function is incorporated for process capability analysis.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.661-666
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• 2005

The specific objectives of this study were to dry yam chips using microwave vacuum drying, freeze drying and hot air drying, then to coat the dried yam chips with ascorbic acid cocrystallized sucrose, and finally to compare the quality of yam chip snack foods with respect to drying and coating characteristics. The microwave vacuum dried sample showed the highest drying rates and much less surface damage than the hot air dried one did. The shape and color of the microwave vacuum dried/coated sample were allocated between those of the freeze dried/coated sample and the hot air dried/coated sample. The freeze dried/coated sample scored excessively low in organoleptic hardness and chewiness to be suitable as a snack. The hot air dried/coated sample was too deep in color, wrinkled, excessively high in organoleptic hardness and chewiness, and excessively low in mouthfeeling. Therefore, the microwave vacuum dried/coated sample presented the best overall attributes as a snack, with respect to organoleptic characteristics, shape, color, and drying rates.

• Journal of Welding and Joining
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• v.31 no.6
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• pp.77-83
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• 2013

3D packaging technology using TSV (Through Silicon Via)has been studied in the recent years to achieve higher performance, lower power consumption and smaller package size because electrical line is shorter electrical resistivity than any other packaging technology. To stack TSV chips vertically, reliable and robust bonding technology is required because mechanical stress and thermal stress cause fracture during the bonding process. Cu pillar/solder ${\mu}$-bump bonding process is usually to interconnect TSV chips vertically although it has weak shape to mechanical stress and thermal stress. In this study, we suggest Insert-Bump (ISB) bonding process newly to stack TSV chips. Through experiments, we tried to find optimal bonding conditions such as bonding temperature and bonding pressure. After ISB bonding, we observed microstructure of bump joint by SEM and then evaluated properties of bump joint by die shear test.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.111-118
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• 2001

Tungsten probe is the most important part of a probe card, which is widely used for the performance test of wafer chips. Electro chemical etching becomes an exclusive choice for mass production of the tungsten probes. In the mass production, not only the shape of the probe but also the shape distribution of machined probes is important. A new method is proposed for the mass production of the tungsten probes. Tungsten wires are separated by a distance, and dipped into electrolyte. The dipping rate is controlled to shape the probes. Several experimental tests are performed to study the machining characteristics. From the test results, machining parameters including electrical conditions and anode position showed significant influences on the shape, repeatability, precision and quality of sharp tips.

• Journal of the Korean Society of Industry Convergence
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• v.2 no.2
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• pp.181-186
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• 1999

For an unmanned machining system, the control and disposal of chips is one of the most serious problems at present. In order to perform chip control, feed/land length($F_L$) was introduced, and using this parameter, the cutting performance and chip breaking characteristics of groove-type and the land -angle-type chip formers were assessed. The specific cutting energy consumed and the shape of broken chips with its breaking cycle time were evaluated to find out the ranges of $F_L$ value where efficient cutting and effective chip breaking could be achieved. The C type chip was found to be the most preferable from the view point of cutting efficiency.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.3
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• pp.250-258
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• 2014

Due to recent industrial growth and development, there has been a high demand for light and highly durable materials. Therefore, a variety of new materials has been developed. These new materials include carbon fiber reinforced plastic (CFRP or CRP), which is a wear-, fatigue-, heat-, and corrosion-resistant material. Because of its advantageous properties, CFRP is widely used in diverse fields including sporting goods, electronic parts, and medical supplies, as well as aerospace, automobile, and ship materials. However, this new material has several problems, such as delamination around the inlet and outlet holes at drilling, fiber separation, and tearing on the drilled surface. Moreover, drill chips having a fine particulate shape are harmful to the work environment and engineers' health. In fact, they deeply penetrate into machine tools, causing the reduction of lifespan and performance degradation. In this study, CFRP woven and unidirectional prepregs were formed at $45^{\circ}$ and $90^{\circ}$, respectively, in terms of orientation angle. Using a high-speed steel drill and a TiAIN-coated drill, the two materials were tested in three categories: cutting force with respect to RPM and feed speed; shape changes around the input and outlet holes; and the shape of drill chips.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.168-170
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• 1994

Carbide-tipped twist drill of new type which is better than traditional H.S.S twist drill has been developed successfully to drill steel work-pieces with high speed. This new carbide drill consists of a characteristic flature of special shape of cutting edge, chip pocket, and flute. The special design of the chip pocket and the flute guarantees both periodic fracture and smooth transport of chips along the flute. The carbide-tipped twist drill also allows one to apply more drilling force than conventional one and produce holes with high accuracy.

• Journal of the Korean Society of Safety
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• v.9 no.4
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• pp.17-28
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• 1994

Chip breaking is important in lathe work for maintaining good surface of the products and safety of operator. The purpose of this study is to investigate the performance of chip breaking and chip shape resulted from the carbide inserts with grooved type and obstruction type chip breaker. Experiments have been performed under the following cutting conditions, (1) constant cutting speed with variable depth of cut and feed rate, (2) constant depth of cut with variable cutting speed and feed rate. Also, the flying distance of chip and it's distribution have been investigated. As a results, good performance of chip breaking can be obtained for small radius of curvature and land width of grooved type chip breaker. And the thickness of chip increase with the increase of feed rate and decrease of cutting speed, and the chip breaking becomes easier with the increase of chip thickness due to the large deformation rate. Obstraction type chip breaker shows better performance of surface roughness than the grooved type. The flying distance of the chips over 90% are less than 1 meter, and the distance decreases as the feed rate decreases.

• Journal of the Korean Society of Visualization
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• v.3 no.2
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• pp.45-50
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• 2005

Electro-osmotic flow (EOF) instability in a microchannel has been experimentally investigated using a micro-PIV system. The micro-PIV system consisting of a two-head Nd:Yag laser and cooled CCD camera was used to measure instantaneous velocity fields and vorticity contours of the EOF instability in a T-shape glass microchannel. The electrokinetic flow instability occurs in the presence of electric conductivity gradients. Charge accumulation at the interface of conductivity gradients leads to electric body forces, driving the coupled flow and electric field into an unstable dynamics. The threshold electric field above which the flow becomes unstable and rapid mixing occurs is about 1000V/cm. As the electric field increases, the flow pattern becomes unstable and vortical motion is enhanced. This kind of instability is a key factor limiting the robust performance of complex electrokinetic bio-analytical devices, but can also be used for rapid mixing and effective flow control fer micro-scale bio-chips.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.4
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• pp.330-336
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• 2014

The continuous chip generated in cutting process deteriorates workpiece, tool, and machine tool system. It is necessary to treat this continuous chip in ductile material machining condition for stable cutting. This paper deals with the chip control method using acoustic emission(AE) signal in pure copper turning operation. AE raw signals, root mean square(RMS) signals and wavelet transformed signals measured in turning process are introduced to analysis for chip patterns. With analysis of AE signals, it is obtained that the produced chip patterns are correlated with the specified AE signals which are transformed by fuzzy pattern algorithm. By this experimental investigation, the chip patterns can be classified at significant level in pure copper machining process and controlled from continuous chips to reduced-length stable chips.