• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.94-102
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• 2007

Applications of bonded dissimilar materials such as large scale integration (LSI) packages, ceramics/metal and resin/metal bonded joints, are very increasing in various industry fields. It is very important to analyze the thermal stress and stress singularity at interface edge in LSI. In order to investigate stress singularities on the bonded interface edges and delamination of die pad and resin in the IC package. In this paper, stress singularity factors(${\Gamma}_i$) and stress intensity factors($K_i$) considering thermal stress in the IC package were analyzed by using the 2-dimensional elastic boundary element method(BEM).

• Land and Housing Review
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• v.11 no.1
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• pp.95-101
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• 2020

In the past few decades, the global population growth and rapid economic development have resulted in significant increases in building energy consumption. To reduce greenhouse-gas emissions and building energy consumption, building materials and energy technologies must be optimized. Building retrofitting is a more efficient method than reconstruction to improve the building energy performance. In order to improve the energy performance of existing buildings, this study proposed energy-efficiency retrofit plans and derived cost-effective retrofit plan. The energy efficient retrofit method is achieved through the packaging of energy technology and the energy and cost reduction effect of the energy efficiency retrofit package are analyzed. As a result of the study, the energy-efficiency retrofit package showed an energy reduction effect of up to 60% or more and a construction cost reduction of about 30%. This study argues that optimal energy and construction cost reduction of existing buildings are possible through the packaging of energy efficiency technology.

• Journal of Welding and Joining
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• v.18 no.2
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• pp.222-222
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• 2000

PBGA(Plastic Ball Grid Array) is composed of some materials such as PCB(Printed Circuit Board), epoxy molding compound, die attach and so on. Reliability of PBGA package is weak compared with plastic packages. The weak points of reliability are the lower resistance to popcorn cracking, which is induced by moisture absorption in PCB, and the pressure cooker test corrosion, which is the basic problem due to the material characteristics of PCB. Introducing the PCB baking and the plasma treatment cleared the popcorn cracking phenomenon. The PCB baking and plasma treatment reduced the epoxy void by eliminating the source of moisture vaporization during the epoxy curing and enhanced the adhesion between PCB and epoxy. Also, plasma treatment enhanced the wettability of epoxy on PCB. The problem of corrosion is cleared using multi-functional epoxy. This type of EMC(Epoxy Molding Compound) is recommended in package using PCB as a substrate. (Received November 19, 1999)

• Journal of Welding and Joining
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• v.18 no.2
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• pp.95-99
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• 2000

PBGA(Plastic Ball Grid Array) is composed of some materials such as PCB(Printed Circuit Board), epoxy molding compound, die attach and so on. Reliability of PBGA package is weak compared with plastic packages. The weak points of reliability are the lower resistance to popcorn cracking, which is induced by moisture absorption in PCB, and the pressure cooker test corrosion, which is the basic problem due to the material characteristics of PCB. Introducing the PCB banking and the plasma treatment cleared the popcorn cracking phenomenon. The PCB banking and plasma treatment reduced the epoxy void by eliminating the source of moisture vaporization during the epoxy curing and enhanced the adhesion between PCB and epoxy. Also, plasma treatment enhanced the wettability of epoxy on PCB. The problem of corrosion is cleared using multi-functional epoxy. This type of EMC(Epoxy Molding Compound) is recommended in package using PCB as a substrate.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.25.1-25.1
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• 2011

Over the past few decades, metallic nanoparticles (NPs) have been of great interest due to their unique mesoscopic properties which distinguish them from those of bulk metals; such as lowered melting points, greater versatility that allows for more ease of processability, and tunable optical and mechanical properties. Due to these unique properties, potential opportunities are seen for applications that incorporate nanomaterials into optical and electronic devices. Specifically, the development of metallic NPs has gained significant interest within the electronics field and technological community as a whole. In this study, gold (Au) pads for surface finish in electronic package were developed by inkjet printing of Au NPs. The microstructures of inkjet-printed Au film were investigated by various thermal treatment conditions. The film showed the grain growth as well as bonding between NPs. The film became denser with pore elimination when NPs were sintered under gas flows of $N_2$-bubbled through formic acid ($FA/N_2$) and $N_2$, which resulted in improvement of electrical conductance. The resistivity of film was 4.79 ${\mu}{\Omega}$-cm, about twice of bulk value. From organic anlayses of FTIR, Raman spectroscopy, and TGA, the amount of organic residue in the film was 0.43% which meant considerable removal of the solvent or organic capping molecules. The solder ball shear test was adopted for solderability and shear strength value was 820 gf (1 gf=9.81 mN) on average. This shear strength is good enough to substitute the inkjet-printed Au nanoparticulate film for electroplating in electronic package.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.4 s.37
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• pp.331-338
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• 2005

The rapid advances in high power light sources and arrays as encountered in incandescent lamps have induced dramatic increases in die heat flux and power consumption at all levels of high power LED packaging. The lifetime of such devices and device arrays is determined by their temperature and thermal transients controlled by the powering and cooling, because they are usually operated under rough environmental conditions. The reliability of packaged electronics strongly depends on the die attach quality, because any void or a small delamination may cause instant temperature increase in the die, leading sooner or later to failure in the operation. Die attach materials have a key role in the thermal management of high power LED packages by providing the low thermal resistance between the heat generating LED chips and the heat dissipating heat slug. In this paper, thermal transient characteristics of die attach in high power LED package have been studied based on the thermal transient analysis using the evaluation of the structure function of the heat flow path. With high power LED packages fabricated by die attach materials such as Ag paste, solder paste and Au/Sn eutectic bonding, we have demonstrated characteristics such as cross-section analysis, shear test and visual inspection after shear test of die attach and how to detect die attach failures and to measure thermal resistance values of die attach in high power LED package. From the structure function oi the thermal transient characteristics, we could know the result that die attach quality of Au/Sn eutectic bonding presented the thermal resistance of about 3.5K/W. It was much better than those of Ag paste and solder paste presented the thermal resistance of about 11.5${\~}$14.2K/W and 4.4${\~}$4.6K/W, respectively.

• FLOWER RESEARCH JOURNAL
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• v.18 no.1
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• pp.57-61
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• 2010

This study was carried out to evaluate the effect of functional packing materials on vase life and quality of Lilium Oriental hybrid 'Le Reve' and Rosa hybrida 'Fire King'. Lily and rose were stored at $5^{\circ}C$ and $20^{\circ}C$ for two days after packing of 25% calcium or 36% wax coated package. When Lilium Oriental hybrid 'Le Reve' was stored in $5^{\circ}C$ after packing of 36% wax coated package, vase life and maintenance of freshness were improved by two days. But when Rosa hybrida 'Fire King' was stored in $5^{\circ}C$ or $20^{\circ}C$after packing of 25% calcium or 36% wax coated package, vase life and maintenance of freshness were not as effective as Lily. In our opinion, functional package seems useful in the storage of cut lily.

• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.124-130
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• 2023

Recently, fan out wafer level packaging, which enables high integration, miniaturization, and low cost, is being rapidly applied in the semiconductor industry. In particular, FOWLP is attracting attention in the mobile and Internet of Things fields, and is recognized as a core technology that will lead to technological advancements such as 5G, self-driving cars, and artificial intelligence in the future. However, as chip density and package size within the package increase, FOWLP warpage is emerging as a major problem. These problems have a direct impact on the reliability and electrical performance of semiconductor products, and in particular, cause defects such as vacuum leakage in the manufacturing process or lack of focus in the photolithography process, so technical demands for solving them are increasing. In this paper, warpage simulation according to the thickness of FOWLP material was performed using finite element analysis. The thickness range was based on the history of similar packages, and as a factor causing warpage, the curing temperature of the materials undergoing the curing process was applied and the difference in deformation due to the difference in thermal expansion coefficient between materials was used. At this time, the stacking order was reflected to reproduce warpage behavior similar to reality. After performing finite element analysis, the influence of each variable on causing warpage was defined, and based on this, it was confirmed that warpage was controlled as intended through design modifications.

• Journal of KSNVE
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• v.4 no.3
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• pp.345-352
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• 1994

Electronic products can be subjected to many different forms of shock. These shocks are usually experienced during transporting the electronic products from a manufacturer to customers. Drop tests are performed to test the product fragility before shipment. Package cushioning materials are often used to protect electronic products from severs shock environments. In the present paper, an algorithm to predict the shock responses of the main mechanical parts is developed by use of the shock analysis in which the modal parameters extracted from vibration test are used. These results are in good agreement with the results of drop test. By use of the shock response prediction algorithm developed herein, it is possible to predict the results of drop test at various drop directions and also to select the optimal package cushioning materials.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.01a
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• pp.224-229
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• 2001

When a semiconductor package is assembled, various materials such as die attach adhesive, lead frame, EMC (Epoxy Molding Compound), and gold wire are used. For better preconditioning performance, the combination between the packaging materials by studying the compatibility of their properties as well as superior packaging material selection is important. But it is not an easy task to find proper packaging material sets, since a variety of factors like package design, substrate design, substrate size, substrate treatment, die size, die thickness, die passivation, and customer requirements should be considered. This research applies case-based reasoning(CBR) technique to solve this problem, utilizing prior cases that have been experienced. Our particular interests lie in building decision support model to aid the selection of proper die attach adhesive. The preliminary results show that this approach is promising.