• Transactions on Electrical and Electronic Materials
• /
• 제15권4호
• /
• pp.217-220
• /
• 2014

We studied the plating properties of Sn-Pb solder according to the shape of the Cu wire's cross-section for photovoltaic ribbon. The thickness of the Sn-Pb layer largely decreased to 29% on a curved Cu surface, compared to a flat Cu surface. This phenomenon is caused by the geometrical decrease in the contact angle of the liquid Sn-Pb solder and an increase in the surface energy of the solid/vapor on the curved Cu surface. We suggest a new ribbon's design where the Cu wire's cross-section is a semi-ellipse. These semi-ellipse ribbons can decrease the use of Sn-Pb solder to 64% and increase the photovoltaic efficiency, by reducing the contact area between the ribbon and cell, to 84%. We also see an improvement of reflectivity in the curved surface.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2011년도 춘계학술발표대회
• /
• pp.48.1-48.1
• /
• 2011

In this presentation, We monitored weather data, such as global irradiance, ambient temperature, temperature of PV module, relative humidity and windspeed for 2 years, for determining accelerated test condition. then, we determined the temperature limit of accelerated test through weather data and FEM analysis. Detailed procedures will be summarized in this work. After analysing outdoor stress such as thermal stress, we decided main failure modes and mechanisms of PV module, especially solder joint of ribbon wire. we carried out the measurement of material properties such as thermal expansion coefficient for planning of accelerated test. we designed accelerated test based on FEM analysis results. we carried out thermal cycling test with 1 cell mini module for 3 months. We monitored the change of electrical performance every 1 week such as Voc, Isc, Pmax, etc. and then, we analized the ribbon wire/electrode intefaces. Detailed results will be summarized in this work.

• 마이크로전자및패키징학회지
• /
• 제24권1호
• /
• pp.103-111
• /
• 2017

본 연구에서는 전동차의 전력 변환 장치로 많이 사용되고 있는 고전압 대전류용(3,300 V/1200 A급) insulated gate bipolar transistor(IGBT) 모듈에 대하여 열 사이클 조건하에서의 열-기계적 응력해석 및 피로수명해석을 수행하였다. 특히 최근 고전압 IGBT용으로 개발되고 있는 구리(copper) 와이어, 리본(ribbon) 와이어를 사용하였을 경우의 응력 및 피로수명을 기존의 알루미늄 와이어와 비교하여 분석하였다. 알루미늄 와이어 보다는 구리 와이어에 응력이 3배 이상 많이 발생하였다. 리본 와이어의 경우 원형 와이어 보다 응력이 더 크게 발생하며, 구리 리본 와이어의 응력이 제일 높았다. 칩과 direct bond copper(DBC)를 접합하고 있는 칩 솔더부의 피로해석을 수행한 결과, 솔더의 크랙은 주로 솔더의 모서리에서 발생하였다. 원형 와이어를 사용할 경우 솔더의 크랙은 약 35,000 사이클에서 발생하기 시작하였으며, 알루미늄 와이어 보다는 구리 와이어에서의 크랙의 발생 면적이 더 컸다. 반면 리본 와이어를 사용하였을 경우 크랙의 면적은 원형 와이어를 사용하였을 경우보다 적음을 알 수 있다. DBC와 베이스 플레이트 사이에 존재하는 솔더의 경우 크랙의 성장 속도는 와이어의 재질이나 형태에 관계없이 비슷하였다. 그러나 칩 솔더에 비하여 크랙의 발생이 일찍 시작하며, 40,000 사이클이 되면 전체 솔더의 반 이상이 파괴됨을 알 수 있었다. 따라서 칩 솔더 보다는 DBC와 베이스 플레이트 사이에 존재하는 솔더의 신뢰성이 더 큰 문제가 될 것으로 판단된다.

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
• /
• pp.98-103
• /
• 2009

In this paper, we test the electrical resistance of flat wire in the PV module. normally solar cell has two kind of flat wire(inter connection ribbon and bus bar ribbon). we found the phenomenon that has a unbalance with resistance when we make a wiling between of string. So, we measurement the resistance of flat wire each other. and analysis of missmatch with resistance between flat wires on PV module. next to survey of IR picture on missmatch flat wire samples for analyze of missmatch with current in the wire. and we perform IR test with solar cell that has a connection with flat wire for test the effect of missmatch resistance on solar cell. Finally we perform the Dark I-V test for survey of effect by the unbalance of resistance. By the result of Dark I-V test, the series resistance of existing connection sample is large more then innovated connection sample.

• 열처리공학회지
• /
• 제30권6호
• /
• pp.251-257
• /
• 2017

The effect of annealing temperature on the martensitic transformation behavior, tensile deformation chracteristics and shape recovery etc., has been studied in TiNi based shape memory ribbon fabricated by coldrolling of wire. TiNi based shape memory wire (${\phi}=500{\mu}m$) of which structure is intermetallic compound could be cold-rolled without process annealing up to the reduction rate in thickness of 50%, but a few cracks appear in cold-rolled ribbon in the reduction rate in thickness of 65%. The $B2{\rightarrow}R{\rightarrow}B19^{\prime}$ martensitic transformation or $B2{\rightarrow}B19^{\prime}$ martensitic transformation occurs in annealing conditions dissipating lattice defects introduced by coldrolling. However, in case of higher reduction rate or lower annealing temperature, martensitic transformation in cold-rolled and then annealed ribbons does not occur. The maximum shape recovery rate of cold-rolled ribbons with the reduction rate of 35 and 65% could be achieved at annealing temperatures of 250 and $350^{\circ}C$, respectively. The shape recovery rate seems to be related to the stress level of plateau region on stress-strain curve.

• 전자공학회논문지D
• /
• 제34D권2호
• /
• pp.1-9
• /
• 1997

For the reduction of parasitic inductance and matching of bonding wire in the package of microwave devices, we propose multiple bonding wires buried in a dielectric material of FR-4 composite. This structure is analyzed using the method of moments (MoM) and compared with the common bondwires and ribbon interconnections. The FR-4 composite is modelled by the cole-cole model which can consider the loss and the variation of the permittivity in a frequency. At 20 GHz, the parasitic reactance is reduced by 90%, 80%, 60% compared to those of a single bonding wire in air, double bonding wires in air and ribbon interconnection in air, respectively. Also, the new bondwire shows very good matching of 60.ohm characteristic impedance and has 15dB, 10dB, 5dB improvement of the return loss and 2.5dB, 0.7dB, 0.2dB improvement of the insertion loss compared to the common interconnections. This technique can minimize the parasitic effect of bondwires in microwave device packaging.

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 1994년도 춘계연구발표회 논문개요집
• /
• pp.68-69
• /
• 1994

• 대한치과교정학회지
• /
• 제43권4호
• /
• pp.186-192
• /
• 2013

Objective: To analyze the fatigue resistance, debonding force, and failure type of fiber-reinforced composite, polyethylene ribbon-reinforced, and braided stainless steel wire lingual retainers in vitro. Methods: Roots of human mandibular central incisors were covered with silicone, mimicking the periodontal ligament, and embedded in polymethylmethacrylate. The specimens (N = 50), with two teeth each, were randomly divided into five groups (n = 10/group) according to the retainer materials: (1) Interlig (E-glass), (2) everStick Ortho (E-glass), (3) DentaPreg Splint (S2-glass), (4) Ribbond (polyethylene), and (5) Quad Cat wire (stainless steel). After the recommended adhesive procedures, the retainers were bonded to the teeth by using flowable composite resin (Tetric Flow). The teeth were subjected to 10,00,000 cyclic loads (8 Hz, 3 - 100 N, $45^{\circ}$ angle, under $37{\pm}3^{\circ}C$ water) at their incisoproximal contact, and debonding forces were measured with a universal testing machine (1 mm/min crosshead speed). Failure sites were examined under a stereomicroscope (${\times}40$ magnification). Data were analyzed by one-way analysis of variance. Results: All the specimens survived the cyclic loading. Their mean debonding forces were not significantly different (p > 0.05). The DentaPreg Splint group (80%) showed the highest incidence of complete adhesive debonding, followed by the Interlig group (60%). The everStick Ortho group (80%) presented predominantly partial adhesive debonding. The Quad Cat wire group (50%) presented overlying composite detachment. Conclusions: Cyclic loading did not cause debonding. The retainers presented similar debonding forces but different failure types. Braided stainless steel wire retainers presented the most repairable failure type.

• Journal of Magnetics
• /
• 제15권4호
• /
• pp.194-198
• /
• 2010

In our present work, we developed a GMI (giant magnetoimpedance) sensor system to detect magnetic fields in the milli gauss range based on the asymmetric magnetoimpedance (AGMI) effect in Co-based amorphous ribbon with self bias field produced by field-annealing in open air. The system comprises magnetoimpedance sensor probe, signal conditioning circuits, A/D converter, USB controller, notebook computer, and program for measurement and display. Sensor probe was constructed by wire-bonding the cobalt based amorphous ribbon with dimensions $10\;mm\;{\times}\;1\;mm\;{\times}\;20\;{\mu}m$ on a printed circuit board. Negative feedback was used to remove the hysteresis and temperature dependence and to increase the linearity of the system. Sensitivity of the milli gauss meter was 0.3 V/Oe and the magnetic field resolution and environmental noise level were less than 0.01 Oe and 2 mOe, respectively, in an unshielded room.

• Current Photovoltaic Research
• /
• 제8권4호
• /
• pp.124-128
• /
• 2020

Output power of photovoltaic (PV) modules installed outdoors decreases every year due to environmental conditions such as temperature, humidity, and ultraviolet irradiations. In order to promote the installation of PV modules, the reliability must be guaranteed. One of the important factors affecting reliability is intermetallic compounds (IMC) layer formed in ribbon solder joint. For this reason, various studies on soldering properties between the ribbon and cell have been performed to solve the reliability deterioration caused by excessive growth of the IMC layer. However, the IMC layer of the PV module interconnected by multi-wires has been studied less than using the ribbon. It is necessary to study soldering characteristics of the multi-wire module for improvement of its reliability. In this study, we analyzed the growth of IMC layer of the PV module with multi-wire and the degradation of output power through damp-heat test. The fabricated modules were exposed to damp-heat conditions (85 ºC and 85 % relative humidity) for 1000 hours and the output powers of the modules before and after the damp-heat test were measured. Then, the process of dissolving ethylene vinyl acetate (EVA) as an encapsulant of the modules was performed to observe the IMC layer. The growth of IMC layer was evaluated using OM and FE-SEM for cross-sectional analysis and EDS for elemental mapping. Based on these results, we investigated the correlation between the IMC layer and output power of modules.