메뉴 건너뛰기
.. 내서재 .. 알림
소속 기관/학교 인증
인증하면 논문, 학술자료 등을  무료로 열람할 수 있어요.
한국대학교, 누리자동차, 시립도서관 등 나의 기관을 확인해보세요
(국내 대학 90% 이상 구독 중)
로그인 회원가입 고객센터 ENG
주제분류

추천
검색

논문 기본 정보

자료유형
학위논문
저자정보

권상현 (인하대학교, 인하대학교 공학대학원)

지도교수
조원승
발행연도
2013
저작권
인하대학교 논문은 저작권에 의해 보호받습니다.

이용수10

표지
AI에게 요청하기
추천
검색

이 논문의 연구 히스토리 (2)

초록· 키워드

오류제보하기
Recently, Electroless Ni/immersion gold(ENIG) surface finish is widely used as surface finish of high performance electro package. But occurred black pad between electroless Ni layer and solder interfacial was being problem of brittle fracture.
In this study, the effect of ENIG, electroless nickel electroless palladium immersion gold(ENEPIG) surface finish on brittle fracture of Sn3.0Ag0.5Cu solder joints were evaluated by high speed shear(HSS) test and board level drop test. High speed shear testing were carried out at various speeds of 100-2000mm/s, failure modes were recorded. In addition, detailed microscopic analysis (SEM, EDS and TEM) was executed on complement surfaces of brittle fracture failures from shear test sample. Drop behavior was evaluated by JEDEC D22 B111.
From results, the effect of brittle fracture increased with increasing shear speed, while ENIG surface finish show high brittle fracture rather than ENEPIG surface finish. Brittle fracture results from Drop test showed a striking similarity. In the results of drop impact test, failure was occurred from the 4 cycle in case of ENIG. ENEPIG showed improved life time on the drop impact that fracture was occurred from 43 cycles.
The failure analysis of drop test and brittle failure on the ENIG, ENEPIG was induced between P-rich Ni layer and (Cu, Ni)6Sn5 IMC layer. Since the Ni-Sn-P layer was located in between the P-rich and the IMC layer, the failure was appeared to occur at the Ni-Sn-P layer.
In addition, the interface was observed with SEM/EDS and TEM for the analysis of P-rich layer (Ni3P) and Ni-Sn-P layer. The effect of brittle fracture can be related with the size of nano-void which is formed in the NiSnP layer between P rich Ni layer and (Cu, Ni)6Sn5. The ENIG sample possessed nanovoids with diameters of 20 ~ 40 nm and the number of nanovoids is significantly high in comparison with ENEPIG. In the ENEPIG sample, the size of nanovoid was about 5 nm and only a few voids were observed. The high brittle fracture rate of ENIG sample was appeared to be due to the high population of nanovoids at the Ni-Sn-P layer. Also, it seemed that scallop-shape (Cu, Ni)6Sn5 IMC can suppress brittle fracture of solder joint due to high external stress and hindrance of crack propagation in ENEPIG surface finish.

목차

국 문 초 록 v
영 문 초 록 vii
목 차 ix
List of Figures xi
List of Tables xiii
1. 서 론 1
2. 이론적 배경 3
2.1 솔더 접합부의 취성파괴 3
2.2 PCB 표면처리 5
2.3 금속간화합물 (Intermetallic compound) 7
2.3.1 Sn / Ni 시스템 7
2.3.2 Sn / Cu 시스템 8
2.3.3 Sn-3.0Ag-0.5Cu based 솔더와 무전해 Ni 계면반응 9
2.4 솔더 접합부 파괴 (Fracture) 10
2.4.1 Black pad 11
2.4.2 취성파괴에 영향을 주는 인자 12
2.4.2.1 전단 속도 (Shear Speed) 12
2.4.2.1 전단 높이 (Shear Height) 13
2.4.2.1 솔더 부피 (Solder Volume) 13
2.4.2.1 표면처리 (Surface Finish) 13
2.4.2.1 등온 시효 (Aging) 14
2.4.2.1 Ni-P 층 두께 (Thickness of Ni-P Layer) 14
2.4.2.1 P 함량 (Phosphorus Content) 14
3. 실험 방법 23
3.1 Test vehicle board 디자인 23
3.2 솔더 접합부 충격 특성 평가 24
3.2.1 고속전단시험 (High Speed Shear Test) 24
3.2.2 낙하충격시험 (Drop Test) 24
3.2.3 취성파괴율 평가 지표 24
4. 결과 및 고찰 33
4.1 전단강도 (Shear Strength) 평가 33
4.2 취성파괴 (Brittle Fracture) 평가 34
4.2.1 파괴모드 (Fracture Mode)분석 34
4.2.2 취성파괴율 (Brittle Fracture rate) 분석 37
4.3 낙하충격 신뢰성 분석 39
4.4 무전해 Ni/Sn 취성파괴 메커니즘 41
4.4.1 금속간 화합물 & 미세구조 41
4.4.2 NiSnP 금속간 화합물 및 Nano-void 영향 43
5. 결 론 47
6. 참고 문헌 48
List of Figures
Fig. 2-1. Phase diagram of Sn-Ni. 16
Fig. 2-2. Phase diagram of Sn-Cu. 17
Fig. 2-3. IMC formation process of ENIG/Sn. 18
Fig. 2-4. Correlation of Fracture mode & shear strength. 20
Fig. 2-5. Fracture mode of solder joint(ductile & brittle fracture). 21
Fig. 2-6. Black pad. 22
Fig. 3-1. Test vehicle board design. 26
Fig. 3-2. Condition of reflow process. 27
Fig. 3-3. Schematic of ball shear test. 28
Fig. 3-4. Schematic view of a test vehicle for a drop test. 30
Fig. 3-5. Schematic of drop tester. 31
Fig. 3-6. Fracture mode determination by the percentage of the brittle fracture region on the fracture surface. 32
Fig. 4-1. Comparison of shear strength(ENIG Vs ENEPIG). 33
Fig. 4-2. Fracture comparision on ductile & brittle area. 34
Fig. 4-3. EDS results on ductile & brittle area. 35
Fig. 4-4. Fracture mod variation with strain rate of HSS test: (a)ENIG, (b)ENEPIG. 36
Fig. 4-5. Comparision of brittle fracture rate. 38
Fig. 4-6. Drop reliability results: (a)ENIG, (b)ENEPIG. 39
Fig. 4-7. Cross-section SEM image of BGA package after drop test (x 10k). 40
Fig. 4-8. Cross section point of Ni-Sn-P layer. 41
Fig. 4-9. Microstructure comparision in the solder: (a)ENIG, (b)ENEPIG. 42
Fig. 4-10. IMC thickness ans shape of solder joints: (a)ENIG, (b)ENEPIG. 42
Fig. 4-11. The TEM results of the (Cu, Ni)6Sn5 IMC/ Ni(P) interfaces. Thickness of P-rich Ni layer and size of nano-void formed in NiSnP layer vary with the type of surface finishing: (a)ENIG, (b)ENEPIG. 44
Fig. 4-12. The TEM micrographs of the (Cu, Ni)6Sn5 IMC/Ni(P) interfaces: (a)ENIG, (b)ENEPIG. 45
Fig. 4-13. EDX results: (1)(Cu, Ni)6Sn5 (2)NiSnP, (3) P-rich Ni layer. 46
List of Tables
Table 2-1. Application of PCB surface finish. 15
Table 2-2. Interfacial reation layers formed between Sn-3.0Ag-0.5Cu solder, and OSP Cu, Ni-P base metalsFormulations of epoxy adhesive samples. 19
Table 3-1. Schematic view of BGA package for a drop test. 29
Table 4-1. Comparison of vrittle fracture rate(rate data). 38

최근 본 자료

전체보기

댓글(0)

0