• Journal of the Korean Ceramic Society
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• v.50 no.3
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• pp.238-243
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• 2013

We investigated the effect of Pb-metal filler added to a hybrid paste(PbO-$Bi_2O_3-B_2O_3$-ZnO glass frit and Pb-powder), for joining flip-chip sat lower temperatures than normal. The glass transition temperature was detected at $250^{\circ}C$ and the softening point occurred at $330^{\circ}C$. As the temperature increased, the specific density decreased due to the volatility of the Pb-metal and boron component in the glass. When the glass was heat-treated at $350^{\circ}C$ for 5 min, XRD results revealed a crystalline $Pb_4Bi_3B_7O_{19}$ phase that had been initiated by the addition of Pb-filler in the hybrid paste. The addition of the Pb-metal filler caused are action between the Pb-metal and glass that accelerated the formation of the liquid phase. The liquid phase that formed, promoted bonding between the flip-chip substrate sat lower temperature.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.671-672
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.705-706
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• 2009

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.289-290
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• 2011

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.09a
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• pp.183-199
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• 2002

Reliability.The reliability strongly depended on the CTE of underfill resin..The fractured portion was identical with the maximum plastic equivalent strain..1 % or less value of the maximum plastic equivalent strain certified more than 1000 cycle of TCT life. UFB.Bonding accuracy was confirmed within2$2{\mu}{\textrm}{m}$..The fundamental bondability of UFB was confirmed with no damage around aluminum pads. Some dislocations and vacancies were observed at the interface, however, the atomic level bonding was confirmed. CBB.Dry process was applied to UBM removal.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.6
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• pp.7-12
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• 2008

• Electronics and Telecommunications Trends
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• v.33 no.6
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• pp.50-57
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• 2018

As devices have evolved, traditional flip chip bonding and recently commercialized thermocompression bonding techniques have been limited. Laser-assisted bonding is attracting attention as a technology that satisfies both the requirements of mass production and the yield enhancement of advanced packaging interconnections, which are weak points of these bonding technologies. The laser-assisted bonding technique can be applied not only to a two-dimensional bonding but also to a three-dimensional stacked structure, and can be applied to various types of device bonding such as electronic devices; display devices, e.g., LEDs; and sensors.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.8
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• pp.879-886
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• 2012

The ultrasonic horn used for bonding of flip chip has been designed to vibrate at a natural frequency. The ultrasonic horn must be manufactured accurately in physical terms, because the small change of mechanical properties may result in the significant change of natural frequency. Therefore, tight tolerance is inevitable to keep the natural frequency in acceptable range. However, since tightening of the tolerance increases the manufacturing cost significantly, trade-off between the cost and accuracy is necessary. In this research, an attempt was made to design the ultra sonic horn within acceptable natural frequency while the manufacturing cost was kept as low as possible. For this purpose, among the 18 tolerances of physical terms of the ultrasonic horn, the most important 4 factors were selected using Taguchi method. The equation to relate those main factors and the natural frequency was made using response surface method. Finally, optimal design scheme for minimum manufacturing cost without a loss of performance was determined using SQP method.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.12
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• pp.1115-1121
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• 2015

Fast inspection of solder ball bumps in ball grid array (BGA) is an important issue in the flip chip bonding technology. Particularly, semiconductor industry has required faster and more accurate inspection of micron-size solder bumps in flip chip bonding, as the density of balls increase dramatically. In this paper, we describe an inspection approach of BGA balls by using 5-step ring illumination device and normalized cross-correlation (NCC) method. The images of BGA ball by the illumination device show unique and distinguishable characteristic contours by their 3-D shapes, which are called as "iso-slope contours". Template images of reference ball samples can be produced artificially by the hybrid reflectance model and 3D data of balls. NCC values between test and template samples are very robust and reliable under well-structured condition. The 200 samples on real wafer are tested and show good practical feasibility of the proposed method.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.11
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• pp.960-967
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• 2013

Shape recognition of solder ball bumps in a BGA (Ball Grid Array) is an important issue in flip chip bonding technology. In particular, the semiconductor industry has required faster and more accurate inspection of micron-size solder bumps in flip chip bonding as the density of balls has increased dramatically. The difficulty of this issue comes from specular reflection on the metal ball. Shape recognition of a metal ball is a very realproblem for computer vision systems. Specular reflection of the metal ball appears, disappears, or changes its image abruptly due to tiny movementson behalf of the viewer. This paper presents a practical shape recognition method for three dimensional (3-D) inspection of a BGA using a 5-step ring illumination device. When the ring light illuminates the balls, distinctive specularity images of the balls, which are referred to as "iso-slope contours" in this paper, are shown. By using a mathematical reflectance model, we can drive the 3-D shape information of the ball in aquantitative manner. The experimental results show the usefulness of the method for industrial application in terms of time and accuracy.