Optimal Ni(P) thickness and reliability evaluation of thin-Au/Pd(P)/Ni(P) surface-finish with Sn-3.0Ag-0.5Cu solder joints
- Authors
- Kim, J.[Kim, J.]; Jung, S.-B.[Jung, S.-B.]; Yoon, J.-W.[Yoon, J.-W.]
- Issue Date
- 15-Oct-2019
- Publisher
- Elsevier Ltd
- Keywords
- Electroless-nickel electroless-palladium immersion gold (ENEPIG); Interfacial reaction; Mechanical strength; Ni thickness; Sn-3.0Ag-0.5Cu; Solder
- Citation
- Journal of Alloys and Compounds, v.805, pp.1013 - 1024
- Indexed
- SCIE
SCOPUS
- Journal Title
- Journal of Alloys and Compounds
- Volume
- 805
- Start Page
- 1013
- End Page
- 1024
- URI
- https://scholarworks.bwise.kr/skku/handle/2021.sw.skku/14884
- DOI
- 10.1016/j.jallcom.2019.07.184
- ISSN
- 0925-8388
- Abstract
- We investigated the interfacial reactions and mechanical reliabilities of different Ni layer thicknesses and P-containing Pd layers in thin electroless-Ni electroless-Pd immersion gold (thin-Au/Pd(P)/Ni(P)) surface-finished printed circuit board (PCBs) with Sn-3.0Ag-0.5Cu (SAC 305) solder joints. To analyze the optimal Ni layer thickness in the thin-Au/Pd(P)/Ni(P) for aging, we evaluated 0.3- to 1.0-μm Ni layers in thin-Au/Pd(P)/Ni(P) PCBs with SAC 305 solder joints aged at 75, 100, 125, and 150 °C for 1000 h. A scallop-type (Cu,Ni)6Sn5 intermetallic compound (IMC) dominantly formed at the bottom and top sides of the interfaces of all Ni joints under all aging conditions. Furthermore, a P-rich Ni layer formed at the interface between the (Cu,Ni)6Sn5 IMC and Cu substrate during aging regardless of Ni layer thickness. The (Cu,Ni)6Sn5 IMCs of the joints with 0.3- and 0.5-μm Ni layers aged at 125 and 150 °C for 1000 h were thicker than those of 0.7- and 1.0-μm Ni layers. In high-speed shear tests, the shear strength reduction rates of the joints with 0.3-μm Ni layer aged at 125 and 150 °C were higher than those of the 0.7- and 1.0-μm Ni layers. The brittle fracture rates of the joints with 0.3- and 0.5-μm Ni layers aged at 150 °C for 1000 h were higher than those of the 0.7- and 1.0-μm Ni layers. We determined that these trends arose from the diffusion barrier role of the relatively thick P-rich Ni layers maintained at the interfaces of the joints with 0.7- and 1.0-μm Ni layers for all aging temperatures and times. In low-speed shear tests, the shear strengths of the joints with 0.3-μm Ni layer were slightly lower than those of the 0.5- to 1.0-μm Ni layers. The low- and high-speed shear strengths of the joint with 0.7-μm Ni layer were similar to those of the 1.0-μm Ni layers for each condition. Therefore, Ni joint thicknesses of over 0.7 μm are expected to provide high reliability for aging. © 2019 Elsevier B.V.
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Collections - Engineering > School of Advanced Materials Science and Engineering > 1. Journal Articles
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