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: In view of the unclear understanding of the basic scientific problems such as the rheological mechanism of seed cotton, especially the lack of research on the creep characteristics of seed cotton, the machine-harvested seed cotton in the Xinjiang region was taken as the research object to find out the compression creep characteristics. The universal material testing machine was used to carry out a one-factor creep test, taking moisture content, feed quality, compression times, and trash content as test factors and instantaneous elastic modulus, hysteretic elastic modulus, viscosity coefficient, and delay time as test indicators. The ANOVA and correlation were analyzed by SPSS, and the creep process of the seed cotton was simulated by ADAMS. Results show that moisture content significantly affects the instantaneous elastic modulus, hysteretic elastic modulus, and viscosity coefficient (p<0.01). In addition, each value of which decreases with the increase in moisture content. Feed quality significantly affects the hysteretic elastic modulus and viscosity coefficient (p<0.05). Moreover, the hysteretic elastic modulus and viscosity coefficient increase with the increase in feed quality. The compression times significantly influence the instantaneous elastic modulus, hysteretic elastic modulus, and viscosity coefficient (p<0.01), each value of which increases with the increase of compression times. Furthermore, the trash content significantly influenced the hysteretic elastic modulus and viscosity coefficient (p<0.05). The absolute error between the simulated and experimental values ek is within -0.011-0.030 mm, and the relative error φk is less than 7%. The experimental results can provide theoretical and data support for the study of rheological characteristics of machine-harvested seed cotton, the design of seed cotton packing devices, and the molding quality of cotton bale (mold). [ABSTRACT FROM AUTHOR]

Sn-based high-temperature Pb-free (HTLF) solder pastes have been developed as a drop-in solution to replace high- Pb solder pastes in power discrete applications. The pastes were designed with Indium Corporation's DurafuseVR technology, to combine the merits of two constituent powders. A SnSb-based Ag/ Cu-containing high-temperature powder, with a melting temperature above 320°C, was designed to maintain high-temperature performance. A Sn-rich SnAgCu-Sb powder, with a melting temperature around 228°C, was added to the paste to enhance wetting and improve joint ductility. In the design, the final joint will have the low-melting phase (the melting temperature >228°C) in a controllable quantity embedded into the high-melting SnSb matrix. HTLF-1, one of the designs, maintained the bond shear strength up to 15 MPa, even around 290°C. Another design, HTLF-2, has a similar bond shear strength as Pb92.5/Sn5/Ag2.5 around 290°C, but exceeds substantially below 250°C. The power discrete components had been built with both HTLF solder pastes for both die-attach and clip-bond through the traditional high-Pb process, which demonstrated the drop-in processing compatibility. The components survived three additional surface mounting (SMT) reflows (peak temperature upto 260°C) and passed moisture sensitivity level 1 (MSL1). This confirmed that the maintained joint strength (comparable to or stronger than high-Pb), helped to keep the joint integrity within the encapsulated components in the following SMT process, even with the controlled quantity of the melting phases above 228°C. Both HTLF solder pastes outperformed Pb92.5/Sn5/Ag2.5 in the resistance from drain to source when power is on (RDS(on)), even after 1,000 cycles of temperature cycling test (TCT) under 255/175°C, which is attributed to the intrinsic lower electrical resistivity of Sn in both HTLF pastes. Microstructural observation had shown no corner cracks for both die-attach and clip-bond joints after TCT. [ABSTRACT FROM AUTHOR]