• 펄프종이기술
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• 제38권4호
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• pp.68-75
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• 2006

Electromagnetic shielding sheet using the carbon and wood fiber mixture was manufactured in an effort to develop an electromagnetic shielding packaging material. Carbon fibers were cut into 5, 10, and 15 mm using the automatic cutting device and blown and dispersed using compression air passed through the fine nozzle. Then carbon fibers were slurried with water (0.1% consistency), and softwood kraft pulp along with cone starch were added. The wet mats were manufactured by dewatering in modified hand-sheet machine. The wet mats were pressed upto $4kgf/cm^2$ in the carbon and wood fiber mixture mat press. The wet mats were dried in the automatic controlled plate dryer. Investigation on the formation and surface structure of the newly developed carbon and wood fiber mixture electromagnetic shielding sheet were carried out using the scanning electron microscopy and the image analyzer. Finally electromagnetic shielding characteristics of the newly developed carbon and wood mixture sheet were measured using net-work analyser. The result was promising in the light of the fact that this method could open a new way to substitute the expensive imported electromagnetic shielding sheet.

• Corrosion Science and Technology
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• 제9권4호
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• pp.153-158
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• 2010

Electrical appliances such as audiovisual equipment and personal computers have recently had heat and electromagnetic problems. In order to solve those problems, 'High heat absorbing pre-painted steel sheet (hereinafter referred to as PSS)', 'High electromagnetic shielding PSS' and 'High heat absorbing and high electromagnetic shielding PSS' have been developed. In this paper, the heat characteristics and electromagnetic shielding properties of PSS are investigated by methods that use enclosures and their mechanisms are discussed. It was found that 'High heat absorbing PSS' and 'High heat absorbing and high electromagnetic shielding PSS'could reduce the heat problem. The mechanism of the heat characteristics was presumed for the high heat absorptivity of the back coating inside the enclosure. And it was also found that 'High electromagnetic shielding PSS' and 'High heat absorbing and high electromagnetic shielding PSS' could shield electromagnetic waves well. The mechanism of the electromagnetic shielding properties was considered for the low transfer impedance of the back coating inside the enclosure. 'High heat absorbing PSS' and 'High electromagnetic shielding PSS' have been adopted as materials for electrical appliances and 'High electromagnetic shielding and high heat absorbing PSS' have been tested for that purpose.

• 한국기계가공학회지
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• 제14권2호
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• pp.81-86
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• 2015

This study investigated electromagnetic interference (EMI) shielding effectiveness (SE) of hybrid conductive fabrics. The coaxial transmission line method was used to measure the EMI Shielding effectiveness of the conductive fabrics. We designed and constructed a measuring system, consisting of a network analyzer and a device that serves as a sample holder and at the same time as a transmission medium of incident electromagnetic waves. The measurements of SE were carried out in a frequency range from 100 MHz to 2 GHz. The results of the EMI shielding experiments showed that the maximum electromagnetic shielding effectiveness (EMSE) values of sandwich type C/A/C (carbon fiber sheet/aluminum foil tape/carbon fiber sheet) and C/Ni/C (carbon fiber sheet/magnetic shielding foil/carbon fiber sheet) samples were 55 dB and 113 dB, respectively, at a frequency of 1.9 GHz.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.73-79
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• 2001

In this paper, shielding effectiveness(SE) of the shielding material of electromagnetic(EM) waves was investigated with actual experiments. The materials used in this study were made up of sputtering, film and powder of conductive materials - Cr, Al, Ag and Cu etc. Also, the polyester film was used as a base material. The experiment was carried out by using a shielding evaluator(Shielding box) TR17302 with an ADVANTEST spectrum analyzer, model R3361C. It was found from the experimental results that silver, copper, aluminum and chromium were good candidates as a shielding material against the EM waves with increasing the SE as the composite was laminated. The characteristics of the SE against the EM waves depended on a mode of preparation of specimen. The effects of density of particles on the SE were studied when the sputtering. The SE strongly depended on the electric resistance by density of sputtering and painting particles. SE increased as the density of particles was increasing.

• 한국산학기술학회논문지
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• 제22권5호
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• pp.530-536
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• 2021

본 논문에서는 전자기기 등에서 전자파 차폐 및 방열소재로 많이 채택되는 동 메쉬 시트와 천연그라파이트 시트를 감압 접착제없이 합지시켜 개발된 차폐 및 방열의 기능을 동시에 가지는 하이브리드시트의 성능 측정결과를 제시하였다. 객관적인 방열 성능을 확인하기 위해 2개의 다른 제품들과 수직 및 수평 열전도도를 각각 측정하여 결과를 비교하였으며, 전자파 차폐 성능은 CISPR 11규격에 따른 복사방출시험을 3m 전자파 무향실에서 진행하여 확인하였다. 수직 열전도도의 경우 제안된 하이브리드 시트가 방열코팅이 된 알루미늄 시트 대비 약 8.63배, 감압 접착제로 인조 그라파이트를 합지시킨 구리 시트에 비해 18.7배 높은 수준이였으며, 수평 열전도도는 인조 그라파이트를 합지시킨 구리 시트에 비해 약 0.64배, 방열 코팅된 알루미늄 시트에 대해서는 약 1.76배로 나타났다. 동일한 열원에서 각 시트들을 적용 후 측정한 결과에서는 제안된 하이브리드 시트가 열방출 기능이 가장 우수하였고 복사방출시험에서는 방사노이즈들이 상당 부분 제거되는 결과를 얻었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.244-249
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• 2004

In this paper, shielding effectiveness(SE) of the shielding paint of electromagnetic(EM) waves was investigated with actual experiments. The shielding paint used in this study were made of powder of conductive materials - Ag, Cu, Al, Sn, Ni. Cr, Graphite and Charcoal etc. with a solubility in oil and water. Also, the paper was used as a base sheet. The experiment was carried out by using a shielding evaluator(Shielding box) TR17302 with an ADVANTEST spectrum analyzer, model R3361C. It was found from the experimental results that silver, copper, nickel were good candidates as a shielding material against the EM waves with increasing the SE as the composite was laminated. The characteristics of the SE against the EM waves depended on a mode of preparation of specimen. The effects of density of particles on the SE were studied about the EM shielding paint. The SE strongly depended on the electric resistance by density of painting particles. SE increased as the density of particles was increasing.

• Composites Research
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• 제33권4호
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• pp.191-197
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• 2020

본 연구에서는 향상된 내구성을 가진 고효율 전자파차폐용 랜덤배향 시트 소재를 개발하기 위해 구리(Copper: Cu)와 니켈 (Nickel: Ni)이 코팅된 탄소섬유(Carbon fiber: CF)와 같은 하이브리드 소재를 습식공정을 통해 제조 하였다. 제조된 시트 소재는 69.4~93.0 dB의 높은 전자파 차폐효율을 보여주었다. 또한 하이브리드 금속으로 코팅된 Ni-Cu/CFs 시트는 Ni표면의 유효한 부식저항성과 기계적 저항성 때문에 가혹한 화학적/열적 환경하에서 매우 우수한 내구성을 보여주었다. 이와 관련하여 Ni-Cu/CF 시트는 Cu/CF 시트와 비교하여 1.7배 긴 수명을 가지는 것을 확인하였다.

• 한국표면공학회지
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• 제39권5호
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• pp.210-214
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• 2006

In order to enhance the electromagnetic shielding efficiency of commercialized cold-rolled steel sheets, we have prepared Ni deposited steel sheets by the electrodeposition method. Surface alloying with Ni and Fe was achieved on a steel sheet by diffusion annealing process. Shielding effectiveness measurement results showed that annealed Ni electrodeposited steel sheets enhanced the shielding efficiency up to about 3 dB in the frequency range of 20 to 200Hz, compared with that of non-deposited steel sheets.

• Composites Research
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• 제28권6호
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• pp.333-339
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• 2015

무전해 도금을 통해 제조한 FeCo 자성 금속 중공형 섬유와 EPDM 고분자를 이용하여 전자파 차폐 복합재를 제작하였다. 열처리 공정을 통하여 섬유의 종횡비를 제어하였으며 중공형 구조로 섬유를 제조한 후, 이를 EPDM 수지에 첨가하여 복합재를 제조하였다. 자성 금속 중공형 섬유의 종횡비가 클수록 낮은 표면 저항 특성과 우수한 전자파 차폐 성능을 나타내었다. 약 $100{\mu}m$ 길이의 자성 금속 중공형 섬유를 이용한 두께 $150{\mu}m$ 전자파 차폐 복합재의 경우 밀도 $1.18g/cm^3$, 약 30 ohm/sq의 표면 저항, 그리고 30 dB의 전자파 차폐 성능을 나타내었다. 이는 종횡비가 큰 섬유에 의한 퍼콜레이션 임계치 이상의 전도성 네트워크 형성과 더불어, 낮은 표면 저항에 기인한 임피던스 차이에 의한 반사 손실 증가, 흡수 손실, 그리고 다중 내부 반사 손실에 의하여 우수한 전자파 차폐 성능을 나타내는 것으로 판단된다.

• 공업화학
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• 제25권3호
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• pp.268-273
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• 2014

본 연구에서는 탄소나노튜브의 전자파 차폐 성능을 향상시키고자 무전해 도금법을 이용하여 다중벽 탄소나노튜브에 니켈을 도입하였다. 니켈 도금된 다중벽 탄소나노튜브의 물리적 특성은 고분해능주사전자현미경, 열중량분석기, 표면저항측정기, 전자파 차폐능 분석기를 이용하여 분석하였다. 니켈 도금된 다중벽 탄소나노튜브의 전자파 차폐 효율은 800 MHz 영역에서 16 dB로 측정되었으며 활성화 처리된 다중벽 탄소나노튜브에 비하여 최대 1.6배 증가하였다. 또한, 평균 표면 저항 역시 $70{\Omega}/sq$로 활성화 처리된 다중벽 탄소나노튜브에 비하여 최대 56% 감소한 수치를 나타내었다. 이러한 결과는 니켈 도금 함량에 비하여 표면의 도금 형태가 전자파 차폐 효율에 더 많은 영향을 끼치기 때문인 것으로 판단된다.