Study on the Reliability of Sn–Bi Composite Solder Pastes with Thermosetting Epoxy under Thermal Cycling and Humidity Treatment

In this study, a Sn–Bi composite solder paste with thermosetting epoxy (TSEP Sn–Bi) was prepared by mixing Sn–Bi solder powder, flux, and epoxy system. The melting characteristics of the Sn–Bi solder alloy and the curing reaction of the epoxy system were measured by differential scanning calorimeter (DSC). A reflow profile was optimized based on the Sn–Bi reflow profile, and the Organic Solderability Preservative (OSP) Cu pad mounted 0603 chip resistor was chosen to reflow soldering and to prepare samples of the corresponding joint. The high temperature and humidity reliability of the solder joints at 85 °C/85% RH (Relative Humidity) for 1000 h and the thermal cycle reliability of the solder joints from −40 °C to 125 °C for 1000 cycles were investigated. Compared to the Sn–Bi solder joint, the TSEP Sn–Bi solder joints had increased reliability. The microstructure observation shows that the epoxy resin curing process did not affect the transformation of the microstructure. The shear force of the TSEP Sn–Bi solder joints after 1000 cycles of thermal cycling test was 1.23–1.35 times higher than the Sn–Bi solder joint and after 1000 h of temperature and humidity tests was 1.14–1.27 times higher than the Sn–Bi solder joint. The fracture analysis indicated that the cured cover layer could still have a mechanical reinforcement to the TSEP Sn–Bi solder joints after these reliability tests.

Experimental Study on Graphene Coating Thermosetting Epoxy Polymer for the Manufacture of Electronic Circuit Boards

Graphene is a microstructure of graphite that has enormous properties and is also one of the carbon allotropes. There are several metals with low strength. The properties of these metals can be increased by coating the graphene. The primary goal of the work is to create composite graphene that exhibits the optimised properties and characteristics that meet the requirements of the industries. The properties of graphene when coated with other metals are studied and their applications in different industrial fields are analysed through several tests and experiments. Research-based on graphene coatings and composites is studied and the properties are adapted.

Polyurethane modified epoxy vitrimer and its stress relaxation behavior

Anhydride cured epoxy vitrimers usually exhibit desired mechanical strength but poor toughness and slow transesterification rate. Therefore, the repairing property of the material was restricted. In this paper, polyurethane modified epoxy vitrimer (PU-Epv) was prepared. PU was introduced into the vitrimer system of tetrahydrophthalic anhydride cured epoxy to improve the toughness of the material. Meanwhile, because of the presence of amino ester, the transesterification reaction was promoted and the activation energy of the transesterification was only 33.59 kJ/mol. In the thermal welding experiment, the material could be welded at least five times, and scratches on the surface of the samples could be efficiently repaired within 30 min. The toughness of the material was improved without damaging the strength. Meanwhile, the hard thermosetting epoxy was endowed with excellent repairing properties to increase the service life of the material.

Research of physically modified antifriction-wear-resistant composite polymer materials and coatings on their basis for machine-building purpose

The article presents the results of studies of the tribotechnical properties of composite thermosetting polymeric materials based on an epoxy compound and ultrasonicated oligomeric fillers operating under conditions of contact interaction with a pulp using the example of raw cotton. Regularities of changes in tribotechnical properties (coefficient of friction, intensity of wear) of composite thermosetting epoxy polymeric materials associated with their filling with organomineral fillers and ultrasonic treatment, in contact with raw cotton have been revealed. The temperature and the magnitude of the electrostatic charge arising in the friction zone of rubbing polymer- cotton and composite-cotton pairs on the type and content of organic-mineral fillers were studied.