JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2023
·Vol. 34
·期 4
·1-9
·
IF 2.8
Zhen Cheng,Ma Limin,Liu Shuang,Wang Yishu,Li Dan,Guo Fu
Electroplating crystalline cobalt–phosphorus (Co–P, with 1 ~ 8 at.% P) is a potential interfacial layer for electronic packaging solder joints, however, the optimal content of P has been lack of systematic research. In this work, crystalline Co–P coatings with P contents of 2, 4 and 6 at.% (Co–2P, Co–4P, Co–6P) were prepared and then bonded with Sn–Ag solder to form Cu/Co– x P/Sn–Ag solder joints. Within aging at 180 °C for 120 h, the diffusion resistance and intermetallic ductility of crystalline Co–P coatings with different P contents were systematically studied. The microstructure, phase composition and mechanical properties of Co–Sn intermetallic compounds (IMCs) were comprehensively characterized using XRD, SEM, EBSD and nano-indentation techniques. The XRD results showed that the Co–P coatings were crystalline structure, with obvious sharp diffraction peaks of β-Co. The Co–4P system exhibited the slowest IMCs growth rate and the best diffusion resistance was obtained in this system, and the kinetic analysis showed that the Co–Sn IMCs growth at the interface was controlled by interface reaction and volume diffusion. It was found that CoSn 3 was generated in the three systems during the aging process, while CoSn 4 and Co–Sn–P were generated only in Co–6P system. Compared with Ni–Sn, Co–Sn exhibited significantly lower IMCs hardness, so the brittle fracture tendency of Co–P solder joints was lower. With the increase of P content, the hardness of Co–Sn IMCs increased first and then decreased, ranging from 3.20 to 4.94 GPa, and the minimum value was noticed in the Co–6P system. Co–4P coating would be a promising barrier layer owing to its good diffusion resistance, Co–6P coating may be used in solder joints with high mechanical load owing to its lowest IMCs hardness, and the Co–2P coating can maintain a balance in anti-diffusion and mechanical properties.
研究领域:
材料科学
·
电子封装技术
✓ 已验证
产品关联
DOI
高影响因子
APPLIED ENERGY
·
2023
·
IF 11.2
Shuang Liu,Limin Ma,Cheng Zhen,Dan Li,Yishu Wang,Qiang Jia,Fu Guo
Bismuth telluride-based thermoelectric (TE) devices were widely used in waste heat recovery due to their high thermoelectric figure of merit (ZT), but the severe diffusion between Sn-based solder and TE pillar generated porous and brittle Sn-Te intermetallic compound (IMC), which seriously restricted the reliable service of devices. Ni-based coating was used but the thick Ni-Te IMC also impaired the properties of TE pillars. In this work, the crystalline Co-P coating was inserted between the p-type TE material Bi 0.5 Sb 1.5 Te 3 and the solder by electrodeposition, and the power generation sustainability of the TE pillar were significantly improved, and the mechanism was revealed. The microstructural characterization proved that the Co-P coating could effectively resist the diffusion of active Sn, Bi, Sb, Cu atoms. Co-P coating would provide support for the structural integrity and performance sustainability of TE pillars. It was worth noting that an ultrathin CoTe 2 IMC layer was formed between the Co-P coating and the Bi-Sb-Te pillar, which was much thinner than the Ni-Te IMC layer reported in the literature. This indicated that Co-P only consumed little thermoelectric elements, but also a good metallurgical bond was formed between the Co-P and the Bi-Sb-Te. After aging at 423 K for 150 h, the maximum output power and average Seebeck coefficient of the TE pillar without coating dropped significantly by 74% and 34%, respectively, and the internal resistance rose by 67%. Remarkably, the maximum output power and average Seebeck coefficient of the TE pillar protected by the Co-P coating only decreased by 14% and 5%, respectively, and the internal resistance only increased by 6%.
研究领域:
材料科学
·
能源工程
✓ 已验证
DOI
高影响因子
MATERIALS CHARACTERIZATION
·
2022
·
IF 4.537
Shuang Liu,Limin Ma,Cheng Zhen,Yishu Wang,Dan Li,Fu Guo
In advanced microelectronic packaging technology, the interfacial brittleness of Cu/Sn solder joints puts forward higher requirements for high-performance diffusion barriers. Cobalt–Phosphorus (Co-P) alloy coating becomes ideal candidates for its good wettability and diffusion resistance. In this work, for Co-P with different crystallinity , the barrier properties of electrodeposited Co-P coatings as well as the mechanical properties of Co-Sn intermetallic compounds (IMCs) at the Co-P/Sn-Ag interface were investigated. According to the XRD results, the crystallinity of the Co-P coating was directly related to the phosphorus (P) content, and Co-P were classified into three types: crystalline state, mixed state and amorphous state. The morphology, composition, phase characterization, and mechanical properties of the Co-Sn IMCs at the interface were investigated by SEM , EPMA , TEM , and nanoindentation methods, respectively. After 180 °C aging test for 120 h, the thickness of CoSn 3 generated at the interface of crystalline Co-4.2 at.% P/Sn-Ag was the smallest among a total of 18 Co-P coatings, where P content ranged from 0.9 at.% to 20.8 at.%, showing the best barrier properties. The hardness of (Co,Cu)Sn 3 at the amorphous Co-P/Sn-Ag interface was the lowest (3.2 GPa), which was only 47% of that of Ni 3 Sn 4 , exhibiting the lowest brittleness tendency. The mixed crystalline-amorphous Co-P could greatly improve the diffusion barrier properties while sacrificing a small degree of brittleness comparing to the amorphous coatings, and had the potential to become a general-purpose alloy coating. This work could provide a scientific basis for the selection of Co-P barrier layers with excellent barrier properties and mechanical properties leading to different application scenario in electronic packaging.
研究领域:
材料科学
·
微电子封装技术
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS & DESIGN
·
2022
·
IF 9.417
Shuang Liu,Limin Ma,Cheng Zhen,Yishu Wang,Dan Li,Fu Guo
Crystalline and amorphous cobalt-phosphorus (Co-P) coatings have their own advantages in interfacial diffusion resistance and mechanical ductility of solder joints, respectively, but it cannot be better at both. In this work, the hybrid crystalline-amorphous Co-P coating (Co-9.1 at.% P) was fabricated and applied on the Cu/Sn interface by controlling the crystallinity through compositional design. Combining the advantages of crystalline and amorphous Co-P, strategies for solder joints with high shear strength, ductile intermetallic compounds (IMCs) and slow interface consumption was proposed. The evolution, microstructure, phase, and mechanical properties of the Co-Sn, Co-Sn-P and P-rich layers in solid-state diffusion were systematically characterized and tested by means of SEM, EPMA, EBSD, TEM, nanoindentation, and shear test. It was found that the hybrid Co-P coating achieved a low consumption rate, 14.2 nm/h, attributing to the partially crystalline structure and the Co-Sn-P exfoliation behavior. In addition, solder joints containing large-thickness ductile Co-Sn IMCs, 3.2–3.6 GPa of hardness, was established. The shear strength after aging reached 75.4 MPa relying on the large thickness of Co-Sn IMCs. Severe mechanical loads would be able to be withstand by virtue of the plastic deformation of ductile IMCs. Hybrid crystalline-amorphous Co-P would be a promising interface material in microelectronic packaging.
研究领域:
材料科学
·
焊接技术
·
微电子学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）