Analysis of Transmission Characteristics in Flexible Printed Circuit Boards
- 주제(키워드) Flexible Printed Circuit Board (FPCB) , Signal Attenuation , Pre-treatment , Effective Dielectric Constant , Drilled Prepreg
- 발행기관 아주대학교
- 지도교수 박용배
- 발행년도 2021
- 학위수여년월 2021. 2
- 학위명 박사
- 학과 및 전공 일반대학원 전자공학과
- 실제URI http://www.dcollection.net/handler/ajou/000000030511
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
Flexible printed circuit boards (PCB) are used to apply for bending position where cannot be implemented in rigid PCBs, and many studies related to a mechanical/physical reliability have been conducted. However, the progress of reliability studies in terms of electrical characteristics has also been begun because the role of the flexible PCB was expanded from simple cable to transmitting the signal of high speed and high frequency. The dielectric materials of a flexible PCBs is polymer that generated dielectric loss depend-ing on the frequency, so reducing the dielectric loss in the desired frequency is the most important factor to increase electrical reliability. When designing a transmission line that transmits in high-speed and electrical circuits, there are many references in the case of rigid PCBs, but there are not references in the case of flexible PCB about selecting materials, transmission line structures and manufacturing process. Therefore, in this study, the transmission characteristics are measured and analyzed using the DUT (Device Under Test) by reflecting various manufacturing options that determine the electrical characteristics of the flexible PCB and quantified. In addition, an idea that can be used not only for flexible PCBs but also for rigid- flex PCBs is proposed. This is a method of laminating after drilling vias only in the desired area on the prepreg without changing the material, so it has been shown that the effective dielectric con-stant can be partially lowered in the same layer.
more목차
1 Introduction 1
1.1 Background 3
1.1.1 High capacity storage 6
1.1.2 High speed interface 8
1.2 Limitations of board level interconnect 10
1.2.1 Electrical loss 10
1.2.2 Impedance matching 11
1.3 Objectives 14
1.4 Organizations 15
2 Transmission characteristics by structures 17
2.1 Transmission line 17
2.2 Transmission line structure in flexible PCB 23
2.3 Coupon design 27
2.4 Results of experiment 30
2.5 Summary 37
3 Transmission characteristics by materials 38
3.1 Electrical properties of dielectric 40
3.2 Low loss materials of flexible PCB 42
3.3 Results of experiment 43
3.4 Summary 49
4 Transmission characteristics by processes 50
4.1 Skin effect 51
4.2 Process affecting copper surface 54
4.2.1 Pre-treatment 54
4.2.2 FCCL process 56
4.3 Results of experiment by pre-treatments 58
4.4 Results of experiment by FCCL process 65
4.5 Summary 67
5 Transmission characteristics by environments 68
5.1 Bending 68
5.1.1 Bending radius of flexible PCB 68
5.1.2 Results of experiment 71
5.2 Humidity 87
5.2.1 Water absorption of polyimide 87
5.2.2 Results of experiment 88
5.3 Summary 93
6 Lowering effective dielectric constant by drilled prepreg 94
6.1 The need for idea 95
6.2 Proposed idea 96
6.3 Results of experiment 98
6.4 Effects of drilled prepreg 101
6.4.1 Impedance 104
6.4.2 Effective dielectric constant 110
6.5 Summary 112
7 Conclusions 113
Bibliography 119
Abstract in Korean 122
