기판 표면 전처리 조건에 따른 전자 패키징 내 금속박막과 절연 기판 사이의 계면 접착에 관한 연구 = A study on the effect of surface pretreatment on interfacial adhesion between metal thin film and substrate for electronic packaging

다국어 초록 (Multilingual Abstract)

Flexible electronics systems are increasingly adopted as future electronics technology due to its merits of cost, speed, density and performance. Although these flexible interconnect and embedded active structure are widely used in electronics application, poor interfacial adhesion between conductor metal and insulating polymer substrate lead to bottleneck of its wide application due to lack of long-term interfacial reliability at actual using conditions.
In this study, wet chemical pretreatment and Ar/O2 ion-beam pretreatment were introduced to improve interfacial adhesion between metal electrode and insulating polymer substrate, and interfacial adhesion was quantitatively measured by peel test. Surface analyses using AFM, FE-SEM and XPS were systematically performed to understand the fundamental adhesion mechanism which focuses on the mechanical interlocking and chemical bonding effect. Finally, we investigated quantitatively the correlation between interfacial adhesion and its fundamental adhesion mechanism as a function of surface pretreatment conditions.
Firstly, interfacial bonding mechanism between electroless-plated Ni and polyimide seems to be closely related the chemical bonding effect which is attributed to the functional carboxyl group by KOH→EDA treatment. By the way, post-baking process is a key step to get stable sample structure while this heat treatment at high temperature could lead to degradation of polyimide cohesive strength due to partially broken carbonyl bonding. Also, the fundamental adhesion mechanism with KOH+EDA treatment are similar to those with KOH→EDA treatment, which lead to cohesive failure inside polyimide itself rather than Ni/polyimide interface. Accordingly, KOH+EDA treatment can partially curtail pre-baking and KOH→EDA process without significantly decrease in the interfacial adhesion between electroless-plated Ni and polyimide. However, interfacial adhesion rapidly decreased with subsequent KMnO4 treatment, which is attributed to removal of the functional group such as carboxyl bonding. Therefore, it is speculated that functional carboxyl group plays an important role in fundamental bonding mechanism between the electroless-plated Ni and polyimide.
Secondly, interfacial bonding mechanism between sputter-deposited Cu and FR-4 substrate seems to be dominated by chemical bonding effect rather than mechanical interlocking effect by Ar/O2 ion-beam treatment. It is found that broken C-C bonding selectively reacted with O2 ions, resulting in strong interfacial bonding between sputter-deposited Cu and FR-4 substrate. Although desmear pretreatment has also caused strong interfacial bonding through selective reaction with carbon and oxygen through rearrangement of C-C bonding, interfacial adhesion between electroless-plated Cu and FR-4 substrate is relatively lower than sputter-deposited Cu on FR-4 treated by Ar/O2 ion-beam. Therefore, it is speculated that desmear pretreatment can result in extensive degradation of FR-4 cohesive strength as a main reason for lower interfacial adhesion than sputter-deposited Cu on FR-4 treated with Ar/O2 ion-beam.

목차 (Table of Contents)

• 목차
• 제1장 서론 1
• 제2장 이론적 배경 3
• 2.1 전자 패키징의 동향 3
• 2.1.1 Flexible Printed Circuit Board(F-PCB) 3
• 2.1.2 Chip-in-Substrate(CiS) 6
• 2.2 박막의 계면 접착력 평가 방법 8
• 2.2.1 계면 접착력의 정의 8
• 2.2.2 박막의 계면 접착력 측정 방법 11
• 2.3 박막의 계면접착력에 영향을 미치는 인자 19
• 제3장 실험 방법 22
• 3.1 니켈 박막/폴리이미드 기판 사이 계면 접착력 평가 시편 제작 22
• 3.1.1 폴리이미드 기판 준비 22
• 3.1.2 폴리이미드 기판 표면의 습식 표면 전처리 24
• 3.1.3 니켈 박막의 무전해 도금과 후속 열처리 26
• 3.2 동 박막/FR-4 기판 사이 계면 접착력 평가 시편 제작 27
• 3.3.1 FR-4 기판 준비 27
• 3.3.2 FR-4 기판 표면의 Ar/O2 이온빔 건식 표면 전처리와 동 박막의 증착 28
• 3.3.2 FR-4 기판 표면의 desmaear 습식 표면 전처리와 동 박막의 무전해 도금 29
• 3.3 동 박막의 전해 도금 30
• 3.4 금속 박막 및 폴리머 기판의 기계적 물성 측정 31
• 3.5 금속 박막/폴리머 기판 사이 계면 접착력 측정 32
• 3.6 폴리머 기판 표면 및 파면 특성 분석 35
• 제4장 연구결과 및 고찰 36
• 4.1 니켈 박막/폴리이미드 기판 사이 계면 접착력 평가 36
• 4.1.1 KOH, EDA 혼용 습식 표면 전처리 효과 36
• 4.1.2 후속 열처리 효과 51
• 4.1.3 KOH, EDA 혼합 습식 표면 전처리 효과 58
• 4.1.4 KMnO4 추가 습식 표면 전처리 효과 67
• 4.2 동 박막/FR-4 기판 사이 계면 접착력 평가 77
• 4.2.1 Ar/O2 이온빔 건식 표면 전처리 효과 77
• 4.2.2 Desmear 습식 표면 전처리 효과 89
• 제5장 결론 99
• 참고 문헌 101
• Abstract 105
• 감사의 글 108