JOURNAL OF ELECTRONIC MATERIALS
·
2017
·Vol. 46
·期 10
·5877-5883
·
IF 1.579
Wang Yan,Han Jing,Guo Fu,Ke Xiaoxing
Grain orientations are a significant factor under high-density current stressing, but there are few literature reports about the influence of grain orientation on electromigration in composite solder joints. Most research relating to the electromigration behavior of composite solders have been carried out by adding different kinds of reinforced particles in order to relieve the electromigration phenomena, while the impacts of grain orientation on the electromigration have been neglected. In this paper, Sn-3.5Ag composite solder joints reinforced by 2 vol.% Cu were fabricated to investigate the effects of Sn grain orientation on electromigration. The one-dimensional single-grained solder joints were stressed under a constant current density of 10 4 A/cm 2 for different times at room temperature. The samples, of which the c -axis of the Sn grains was nearly parallel to the electron flow direction, exhibited serious electromigration-induced phenomena after current stressing for 528 h. However, electromigration was not observed in the samples where the Sn grains had their c -axis perpendicular to the electron flow direction. Therefore, the grain orientations have a great influence on the electromigration behavior in composite solders and Cu atoms moved faster along the c -axis of the Sn grains than along the a - and b -axes during current stressing.
研究领域:
材料科学
·
电子封装技术
·
金属材料学
·
微电子可靠性
·
物理冶金
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2018
·Vol. 29
·期 7
·5954-5960
·
IF 2.324
Wang Yan,Wang Yishu,Han Jing,Tan Shihai,Guo Fu
Sn grain orientation in solder matrix has recently been considered as one of the principal failure contributions in lead-free solder joints. Since β -Sn exhibits high anisotropy, the differences of electromigration behavior of solder joints with various grain orientations are dramatic. With different angle ( θ ) between the c -axis of Sn grain and the direction of electron flow, the solder joints often demonstrate varying degrees of electromigration-induced damage. The present investigation illustrated significant differences in microstructural features on the surface of Cu reinforced composite solder joints, even with similar angle θ . Two Cu particles reinforced Sn 3.5 Ag composite solder joints with the similar angle θ of 35° and 40° were selected to investigate the effects of Sn grain c -axis on electromigration under high current stressing for 528 h. A large number of Cu 6 Sn 5 compounds were observed and occupied nearly the whole surface with clear polarization effect in one sample. In contrast, very few Cu 6 Sn 5 were found on the surface of the solder matrix in the other sample after current stressing, and the Cu 6 Sn 5 which was formed after reflow disappeared with subsequent current stressing. Even though polarization effect was not obvious, and the cathode interfacial dissolution was observed on such sample. Systematic study revealed that the angle θ alone was not a sole factor to determine the electromigration damage. It has to be considered along with the coordinate system containing the orientation of the c -axis of the Sn grain, a more dominative factor for the diffusing species.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ELECTRONIC MATERIALS
·
2020
·Vol. 49
·期 3
·2159-2163
·
IF 1.774
Wang Yan,Wang Yishu,Ma Limin,Han Jing,Guo Fu
Because of its tetragonal structure, β -Sn exhibits anisotropy in electromigration behavior. The diffusivity of Cu atoms along the c -axis of Sn is much faster than that along the a -axis; therefore, the orientation of the c -axis exerts a strong influence on Cu atomic motion. In this work, the effect of Sn grain c -axis on Cu atomic motion was investigated by using Cu reinforced Sn3.5Ag composite solder joints. The microstructure and morphology of the solder joints were characterized by scanning electron microscopy (SEM) equipped with a backscattered electron (BSE) detector. It was found that intermetallic compounds (IMCs) in the solder matrix were formed due to the migration of Cu atoms to the surface of the solder joint under current stressing. There was a large amount of IMCs on the solder matrix which protruded from the solder matrix. By changing the direction of electron flow, i.e. changing the anode and the cathode side, the IMCs which formed after current stressing in the solder matrix disappeared and the protruding Sn remained unchanged. The results revealed that the growth of IMCs was closely related to the migration of Cu atoms, while Cu atomic motion depended on the orientation of the Sn grain c -axis.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2018
·Vol. 29
·期 15
·13180-13187
·
IF 2.324
Wang Yan,Wang Yishu,Ma Limin,Han Jing,Guo Fu
Due to the asymmetric structure of Sn unit cell, the electromigration behaviors of Sn based solder joints were significantly depended on the crystal orientation of Sn grain. The present investigation illustrated the effect of Sn grain c -axis on the intermetallic compounds (IMCs) growth under current stressing. The Cu particles reinforced Sn3.5Ag solder joint was selected to obtain various observed surfaces of the sample after 46 days current stressing. The front side, back side, right side and anode side of the sample represented different phenomena, which reflected and proved the importance of c -axis orientation on Cu atomic migration in three-dimension space. Besides, another composite solder joint was polished severe times on the observed surface which was full of IMCs. It showed that the IMCs were covered on the Sn-based solder, and there was crack at the cathode underneath the front surface after 38 days current stressing. The IMC growth behavior would be well understood by systematic study in this work.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ELECTRONIC MATERIALS
·
2017
·Vol. 47
·期 2
·1705-1712
·
IF 1.579
Han Jing,Wang Yan,Tan Shihai,Guo Fu
Electromigration is a major reliability problem in composite solder joints. Due to the anisotropy of the β -Sn crystal structure, the Sn grain orientations present in the solder matrix dominate the principal failure mechanism in solder joints under electric current stressing. In this work, the Cu 6 Sn 5 growth behavior in Cu 6 Sn 5 -reinforced composite solder joints with three different Sn grain orientations was investigated at current density of 10 4 A/cm 2 at room temperature. Micron-sized Cu particles were added to Sn-3.5Ag solder at 2% volume fraction using an in situ method. After current stressing for 528 h, the polarity effect in the composite solder joint was greatest for an angle ( θ ) between the c -axis and electron flow direction of 30°, resulting in higher growth rate of Cu 6 Sn 5 in the solder matrix compared with composite solder joints with θ of 60° or 90°. There were no noticeable changes in the composite solder joint with θ of 90°. The growth behavior of Cu 6 Sn 5 , Cu atomic motion, and Cu diffusivity in the composite solder joints with different Sn grain orientations were analyzed in detail.
研究领域:
材料科学
·
电子工程
✓ 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）