• Bulletin of the Korean Chemical Society
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• v.28 no.2
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• pp.188-192
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• 2007

In this work, the effects of chemical treatment of polyimide films were studied by FT-IR, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angles. The adhesion characteristics of the films were also investigated in the peel strengths of polyimide/aluminum films. The increases of surface functional groups of KOH-treated polyimide films were greatly correlated with the polar component of surface free energy. The peel strength of polyimides to metal substrate was also greatly enhanced by increasing the KOH treatment time, which can be attributed to the formation of polar functional groups on the polyimide surfaces, resulting in enhancement of the work of adhesion between polymer film and metal plate.

• Korean Journal of Metals and Materials
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• v.49 no.4
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• pp.321-328
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• 2011

The 30 nm-thick Ni layers was deposited on a flexible polyimide substrate with an e-beam evaporation. Subsequently, we deposited a Si layer using a catalytic CVD (Cat-CVD) in a hydride amorphous silicon (${\alpha}$-Si:H) process of $T_{s}=180^{\circ}C$ with varying thicknesses of 55, 75, 145, and 220 nm. The sheet resistance, phase, degree of the crystallization, microstructure, composition, and surface roughness were measured by a four-point probe, HRXRD, micro-Raman spectroscopy, FE-SEM, TEM, AES, and SPM. We confirmed that our newly proposed Cat-CVD process simultaneously formed both NiSi and crystallized Si without additional annealing. The NiSi showed low sheet resistance of < $13{\Omega}$□, while carbon (C) diffused from the substrate led the resistance fluctuation with silicon deposition thickness. HRXRD and micro-Raman analysis also supported the existence of NiSi and crystallized (>66%) Si layers. TEM analysis showed uniform NiSi and silicon layers, and the thickness of the NiSi increased as Si deposition time increased. Based on the AES depth profiling, we confirmed that the carbon from the polyimide substrate diffused into the NiSi and Si layers during the Cat-CVD, which caused a pile-up of C at the interface. This carbon diffusion might lessen NiSi formation and increase the resistance of the NiSi.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.487-488
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• 2005

We have investigated the Electro-Optical Characteristics for a nematic liquid crystal (NLC) alignment with rubbing alignment method on polyimide surfaces using plastic substrates. It was found that monodomain alignment of NLC is obtained with rubbing alignment method on polyimide surfaces using thin plastic substrates. EO characteristics of the TN-LCD with a rubbed PI surface based on polymer are almost the same as that of the TN-LCD with a rubbed PI surface based on glass. However, the transmittances of the TN-LCD with a rubbed PI surface based on polymer is less than that with a rubbed PI surface based on glass.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.8
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• pp.666-670
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• 2007

Aluminuim doped zinc oxide(ZnO:AL)Films have been prepared on Polyimide(PI) and Coming 7059 glass substrates by r.f. magnetron sputtering method. The structural of the ZnO:Al films were studied in accordance with various deposition R.F power and working pressure by XRD, SEM. And The electrical and optical properties of ZnO:Al films were characterized by Hall effect and UN visible spectrophotometer measurements, ZnO:Al films had were hexagonal wurtzite structure and dominant c-axis orientation. The R.f power and working pressure for optimum condition to fabricate the transparent conductive films using a PI substrate were 2 mTorr and 100W, respectively. The resistivity of the ZnO:Al films prepared under this condition were $9.6{\times}10^{-4}{\Omega}cm$. The optical transmittance of 400nm thick films at 550nm is ${\sim}85 %$.

• Journal of Mechanical Science and Technology
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• v.18 no.9
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• pp.1572-1581
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• 2004

The purposes of the paper are to apply the axiomatic design methodology to the design of PBGA package with polyimide coating under hygrothermal loading in the IR soldering process and to suggest more reliable design conditions by stress analysis. The analysis model is a 256-pin perimeter Plastic Ball Grid Array (PBGA) package with the polyimide coating surrounding chip and above surface of BT-substrate. The polyimide coating is suggested to depress the maximum stresses occurred on the stress concentration positions. The axiomatic design methodology is proved to be useful to find the more reliable design conditions for PBGA package. Finally, the optimal values of design variables to depress the stress in the PBGA package are obtained.

• Journal of the Korean institute of surface engineering
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• v.25 no.2
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• pp.90-96
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• 1992

Thed effects of sputter gas pressure and substrate surface micro-roughness on the microstructure and surface topography have been investigated in the Cu thin films sputter deposited onto polyimide substrates. The surface roughness of polyimide was controlled by oxygen rf plasma treatment. In the Cu film deposited at the pressure of 5 mtorr, the surface is smooth and the columnar structure is not visible regardless of polyimide surface more open boundaries. The polyimide surface roughness enhances these effects, These phenomena can be explained in therm of atomic shadowing effect.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.7
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• pp.481-485
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• 2003

Amorphous silicon (a-Si:H) based TFT process has been studied at the maximum temperature of 15$0^{\circ}C$ with 25${\mu}{\textrm}{m}$ thick flexible and adhesive tape type polyimide foil substrate, which has benefit on handling a rugged, flexible plastic substrate trough sticking simply it to glass. This paper summarize the process procedure of the TFT on the plastic substrate and shows its electrical characteristics in comparison with glass substrate using primarily the ON/OFF current ratio and the field effect mobility as the quality criterion. The a-SiN:H coating layer played an important role in decreasing surface roughness of plastic substrate, so leakage current of TFT was decreased and mobility was increased. The results show that high quality a-Si:H TFTs can be fabricated on the plastic substrates through coating a rough plastic surface with a-SiN:H.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.4 s.33
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• pp.1-5
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• 2004

A multi-layer flexible substrate is composed of copper(Cu)/polyimide that are known as good electrical conductivity, and low dielectric constant, respectively. In this study. conductor line of $5{\mu}m$-pitch was successfully fabricated without non-uniform pattern shape by electroplating copper and coating polyimide on patterned stainless steel. For multi-layer flexible substrate, via holes were drilled by UV laser and filled with electroplating copper and tin. And then, the PI layer with vias and conductor lines was stripped from stainless steel substrate. The PI layers were laminated at once with careful alignment between layers. Solid state reaction between tin and copper during lamination formed the intermetallic compounds of $Cu_6Sn_5$($\eta$-phase) and $Cu_3Sn$($\epsilon$-Phase) and achieved a complete inter-connection by vertically positioning the plugged via holes on via pad. The via formation process has several advantages; such as better electrical property and lower cost than V type via and paste via.

• Transactions on Electrical and Electronic Materials
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• v.6 no.3
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• pp.106-109
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• 2005

We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with in-situ photoalignment method on polyimide (PI) surfaces using polymer films. Especially, we studied in-situ photoalignment changing heating temperature from $50^{\circ}C\;to\;120^{\circ}C$ on the polymer film. The LC aligning capabilities and pretilt angle on the polymer substrates were better than those on the glass substrate using in-situ photoalignment method. It is considered that this increase in pretilt angle may be attributed to the roughness of the micro-groove substrate induced by the in-situ photoalignment. As temperature of heated subtrate and UV exposure time increase, pretilt angle of the cell used polymer film increased. It is considered that the heating temperature of substrate is attributed to generate pretilt angle. Also, electro-optical performances of the in-situ photoaligned TN cell using the polymer substrate are almost the same as that of the TN cell using the glass substrate.

• Proceedings of the KAIS Fall Conference
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• 2000.04a
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• pp.84-84
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• 2000