• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.3
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• pp.408-414
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• 2012

Screen printing is a printing method that uses a woven mesh to support an ink-blocking stencil by transferring ink or other printable materials in order to form an image onto a substrate. Recently, the screen printing method has applied to micro-electronic packaging by using solder paste as a printable material. For the screen printing of solder paste, metal masks containing a number of micro-holes are used as a stencil material. The metal mask undergoes deformation when it is installed in the screen printing machine, which results in the deformation of micro-holes. In the present study, finite element (FE) analysis was performed to predict the amount of deformation of a metal mask. For an efficient calculation of the micro-holes of the metal mask, the sub-domain analysis method was applied to perform FE analyses connecting the global domain (the metal mask) and the local domain (micro-holes). The FE analyses were then performed to evaluate the effects of slot designs on the deformation characteristics, from which more uniform and adjustable deformation of the metal mask can be obtained.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.10
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• pp.774-781
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• 2003

The important factors that cause position error in X-Y robot are inertial force, frictions and spring distortion in screw or coupling. We have to estimate these factors precisely to correct position errors, Which is very difficult. In this paper, we makes systems to inspect metal stencil which is used to print solder paste on pads of SMD of PCB with low precision X-Y robot and vision system. To correct position error that is caused by low precision X-Y robot, we defines position error vector that is formed with position of objects that exist in reference and camera image. We apply MHT(Modified Hough Transformation) for the aim of determining the dominant position error vector. We modify reference image using extracted dominant position error vector and obtain reference image that is the same with camera image. Effectiveness and performance of this method are verified by simulation and experiment.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.4
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• pp.83-89
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• 2014

Solder paste plays a crucial role as the widely used joining material in surface mount technology (SMT). The understanding of its behaviour and properties is essential to ensure the proper functioning of the electronic assemblies. The composition of the solder paste is known to be directly related to its rheological behaviour. This paper provides a brief overview of the solder paste behaviour of four different solder paste formulations, stencil printing processes, and techniques to characterize solder paste behaviour adequately. The solder pastes are based on the Sn-3.0Ag-0.5Cu alloy, are different in their particle size, metal content and flux system. The solder pastes are characterized in terms of solder particle size and shape as well as the rheological characterizations such as oscillatory sweep tests, viscosity, and creep recovery behaviour of pastes.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.3
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• pp.11-16
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• 2006

A new method to fabricate metal electrodes on side wall of the microchannel is presented. Electrical signal can be measured by the metal electrodes on channel side wall when microparticles pass through a polymer microchannel. 3 dimensional metal electrodes on channel side wall could be fabricated by local deposition of metal through a shadowmask and inclined evaporation. The polymer microchannel with side wall electrodes could be precisely aligned onto metal contact patterns on pyrex glass. The impedance measurement test showed possibility of electrical signal measurement using the fabricated device.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1462-1465
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• 2004

A new method to fabricate metal electrodes on side wall of the microchannel is presented. Coulter counter allows to count the number of cell passing through the microchannel by detecting impedance variation between two electrodes. The relative position of two electrodes is important for sensitivity of impedance measurement. 100nm thick Al electrodes are deposited on the channel side wall by means of shadow evaporation.

• Korean Institute of Interior Design Journal
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• no.17
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• pp.157-165
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• 1998

This study aimed to identify characteristics of design and decoration of Danish peasant furniture especially painted storage furniture used during the 18-19th century before modern design movement of Internationalism prevailed all over the world. Owing to the fact that Danish peasant furniture were made of available conifer around the farms painting method was preferred to carving. Remoted from main land of western and southern Europe Scandinavian countries longed to imitate their Baroque style architecture and furniture made of marble of hard woods. Painting method was adopted to disguise cheap wood so that it looked like expensive or exotic materials such as marble oak metal granite etc. what they could not afford to buy. Eventually they evolved unique materials equipments and methods for imitation painting in order to decorate folk storage furnitures as well as formal architecture : palaces churches and other official buildings,. Marbling clouds marbling graining stencil spatter painting trompe-I'oeil were common to imitate stones or hard woods. Strong and bright colors had good combination together with dull colors on the Danish peasant painted furniture.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.291-294
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• 2003

In this paper, 2D and 3D inspection algorithm for printed solder on PCB is introduced. The aim of inspection is the detection of error such as rich solder poor solder and missing solder. For Inspection, laser distance sensor is used. For 2D inspection, laser image that is created by normalizing laser data between 0 and 255 are used. Reference Image is made using gerber file. Image processing algorithm is used for 2D inspection. By adding thickness of metal stencil to laser image, volume for solder can be calculated and 3D inspection is carried out.