<p>With the rapid development of communication technology, as one of the key raw materials for printed circuit board (PCB) copper plating technology, higher requirements are put forward for the forming and manufacturing precision of phosphorous copper balls. In this paper, the warm skew rolling of phosphorous copper ball is adopted. In order to analyze the forming mechanism for phosphorous copper ball during skew rolling, by using commercial FEM software Simufact, an FE simulation of warm skew rolling was established to predict the distribution of strain field, stress field, temperature field and law of metal flow for phosphorous copper balls with a diameter of 30mm. The FE-simulation results show that the metal at the surface of the phosphorous copper balls flowed faster than the metal at the center. Meanwhile, the total plastic strain of the connecting neck at both ends of the phosphorous copper ball was the maximum due to the extrusion of the flange between the two rollers. In addition，the FE effective-stress distribution approximately presents four symmetrical parts. After the roll extrusion, the effective-stress value of the connecting neck at both ends of the rolling piece was the maximum, about 180MPa. The effective-stress value gradually decreases with the increase of the distance from the contact area. In the end, the FE temperature distribution shows that the temperature on the surface of the connecting neck of the rolling piece was the maximum, and the temperature gradually decreases along the radial and axis direction to the center of the rolling piece. Besides, the temperature of the connecting neck and its two sides were approximately butterfly shaped. This is because the connecting neck of the rolling piece was the largest deformation of the convex edge extrusion of the roller, and the most heat was generated. The butterfly temperature distribution also indicates that the axial deformation of the rolled piece decreases gradually from the centripetal surface. To validate the FE simulation results, warm skew rolling was conducted under the following process conditions: the initial temperature of 600°C, roller angle of 3° and rotational speed of 60 min<sup>–1</sup>.After the warm skew rolling, phosphorous copper ball with a diameter of φ30 mm was manufactured, using an skew rolling machine. Comparing the experimental and predicted results for phosphorous copper ball, we found that the predicted phosphorous copper ball was consistent with the experimental. This indicates that the phosphorous copper ball formation mechanism can be revealed, using the developed FE simulation of warm skew rolling.</p>

Finite Element Analysis of Deformation Characteristics in Warm Skew Rolling of Copper Ball

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.