무전해 도금법으로 전착된 Ni-W-P 기반의 확산방지층 형성 및 이를 이용한 Bi-Te계 열전모듈의 제작 = Fabrication of Bi-Te thermoelectric module using electroless Ni-W-P diffusion barrier

다국어 초록 (Multilingual Abstract)

Thermoelectric materials are a new alternative energy material that can convert heat energy from a temperature gradient into electric energy, or reverse current, with one end of the material absorbing endothermic heat. Currently, the thermoelectric material exhibiting the best thermoelectric properties near room temperature is a Bi-Te alloy. The thermoelectric module is a structure in which p-type and n-type thermoelectric elements are formed by soldering (bonding) to a copper electrode formed on a ceramic. Performance and lifetime of the module as a whole are different depending on the performance of the bonded portion. However, the disadvantage of Sn soldering joints is the formation of an intermetallic compound between Te of the Bi-Te device, which deteriorates the module performance. In order to prevent such compound formation, Ni-W-P electroless plating was performed on a Bi-Te device as to form a diffusion- preventing layer to form a Ni-W-P plating layer as a barrier layer. In this study, the surface roughness of the thermoelectric device was adjusted by using the sand -blasting technique, and Ni-W-P plating was performed to improve the adhesion of the plating layer. Thereafter, the bonding strength between the thermoelectric element and the Cu electrode was measured by a soldering method using a bonding tester. As a result of analysis of the cross section of the joint using FE-EPMA, the Ni-W-P layer served as the barrier layer. The bond strength improved after heat treatment. In this study, we have analyzed the factors that improve the bonding strength by Ni-W-P plating.

목차 (Table of Contents)

• Ⅰ. 서론 1
• Ⅱ. 이론적 배경 4
• 2.1. 열전효과(Thermoelectric effect) 4
• 2.1.1 제백 효과(Seebeck effect) 4
• 2.1.2 펠티에 효과(Peltier effect) 7
• 2.1.3 톰슨효과(Thomson effect) 8
• 2.2. 열전모듈(Thermoelectric module)의 구성요소 및 구조 10
• 2.2.1 열전재료의 성능 . 10
• 2.2.2 Bi-Te계 열전재료 13
• 2.2.3 방전 플라즈마 소결법 (Spark Plasma Sintering) 17
• 2.2.4 열전모듈(Thermoelectric module) 19
• 2.2.5 확산 방지막 (Diffusion barrier) . 21
• 2.3 무전해 도금 (Electroless plating) . 22
• Ⅲ. 실험 방법 23
• 3.1 Bi-Te계 열전 재료의 제작 23
• 3.1.1 방전 플라즈마 소결(Spark Plasma Sintering) . 23
• 3.1.2 Bi-Te계 열전 소재의 특성평가 . 26
• 3.2 Bi-Te계 열전모듈의 제작 . 30
• 3.2.1 Bi-Te계 소결체의 전처리 . 30
• 3.2.2 무전해 Ni-W-P 도금 . 31
• 3.2.3 Bi-Te계 열전모듈의 제작 31
• 3.2.4 Bi-Te계 열전모듈의 접합강도 평가 35
• Ⅳ. 실험결과 및 고찰 . 38
• 4.1 열전소재의 열전 특성평가 . 38
• 4.1.1 전기적 특성 38
• 4.1.2 열적 특성 . 38
• 4.1.3 무차원 성능지수 (ZT) . 38
• 4.2 열전 모듈의 접합강도에 미치는 무전해 Ni-W-P도금 확산방지층의 영향 43
• 4.2.1 무전해 Ni-W-P 분석 43
• 4.2.2 Bi-Te계 열전모듈 계면 FE-EPMA 면 분석 . 47
• 4.2.2.1 열전소재/도금층/솔더부 계면 FE- EPMA 면분석 47
• 4.2.2.2 솔더/전극부 계면 FE-EPMA관찰 . 54
• 4.2.3 Bi-Te계 열전모듈의 접합강도 측정 및 파단면 관찰 57
• 4.3 열전모듈 성능 평가 63
• Ⅴ. 결론 . 65
• 참고문헌 66
• 영문초록 71