Joint Formation in Multilayered Ultrasonic Welding of Ni-Coated Cu and the Effect of Preheating

Abstract

Multilayered ultrasonic welding (USW) is widely used in joining of electrodes or tabs in lithium-ion batteries. To achieve quality joints and enhance the welding process robustness, an improved understanding of the joint formation is highly desirable. In this paper, USW of four-layered Ni-coated Cu is studied to investigate the joint formation at a single interface and joint propagation from interface to interface under both ambient and preheated conditions. The results indicate that joint formation involves three major mechanisms: Ni–Ni bonding with minimal mechanical interlocking, Ni–Ni bonding with moderate mechanical interlocking, and a combination of Ni–Ni bonding, Cu–Cu bonding, and severe mechanical interlocking. Results also show that joints propagate from the interface close to the sonotrode side to that close to the anvil side. It is further observed that the joint formation can be accelerated and the joint strength can be improved with process preheating, especially at the interface closest to the anvil. The effect of preheating is most significant during the early stage of the process, and diminishes as process progresses. The favorable effects of preheating improve the robustness of multilayered USW.

Conductive materials for connecting tires of multi-element accumulator traction batteries

“…По результатам проведенных испытаний можно сделать следующие выводы: при токах разряда АКБ до 18 А (кратковременных до 35 А) наиболее приемлемым является использование в качестве токопроводящих шин никелевой ленты сечением 0,8 ç 10 мм, а наиболее эффективным и быстрым методом сварки -точечная сварка, поскольку сварное соединение никель-никель формируется в этом случае в течение нескольких миллисекунд и элемент питания в точке контакта не успевает нагреться до критических температур [9,10]. При токах разряда выше 20 А целесообразно использование в качестве токопроводящих шин материалов на основе меди, имеющих в 4-5 раз более высокую удельную электропроводность [11].…”

A review on ultrasonic spot welding of copper alloys

“…Therefore, materials under the ridges of sonotrode tip will be squeezed into the valley area of the sonotrode knurl pattern, as shown in Figure 1. In addition, with increasing the welding energy, plastic deformation becomes more severe for the top three Cu sheets, especially in the valley area [14]. The top sheet gradually becomes thinner and is almost perforated at 1400 J, which is poor to the joint strength.…”

Effects of Lap Configuration on Mechanical Properties and Composition Distribution of Three-layer Overlapped Laser Weldments on Al/Cu Dissimilar Materials

“…Various joining techniques involving the use of lasers [14][15][16], friction stir [17,18], diffusion [19], and ultrasonic welding [20][21][22][23] have been employed in the fabrication of Al−Cu dissimilar joints. In fusion welding, such as laser welding, more severe IMP formation at the dissimilar material joint results, as the melting rate of materials in this process is higher compared to other solid-state welding processes such as ultrasonic welding.…”