超薄超细智能手机热管拉拔工艺及组织性能演变

Drawing process and evolution of microstructure and properties for heat pipe of ultra-thin and super-fine in smartphone

在液压直拉机上采用游动芯头拉拔成形智能手机用超薄超细无氧铜热管,研究了拉拔工艺对拉拔过程断管的影响,观察各道次铜管晶粒组织演变和拉拔过程中的力学性能和导电性能变化。结果表明:无氧铜管经游动芯头多道次拉拔,晶粒不断趋于沿拉拔方向的纤维状,同时抗拉强度和维氏硬度不断提升,而拉拔变形对导电率的影响比较小。当无氧铜管累计变形量达75.8%时,铜材的抗拉强度为416.5 MPa,继续拉拔容易发生断管问题,需进行中间退火。经过8道次拉拔变形,1次中间退火处理后,得到抗拉强度为403.8 MPa、伸长率为1.78%、导电率为98.85%IACS、外径公差为±0.02 mm、壁厚公差为±0.01 mm的Ф2 mm×0.08 mm规格的超薄超细智能手机热管。

The oxygen-free copper heat pipes of ultra-thin and super-fine in the smartphone were drawn by a hydraulic drawing machine with a floating plug,and the influence of drawing process on pipe breakage during the drawing process was studied.Then,the microstructure evolution of grains in copper pipe and the changes of mechanical and electrical conductivity properties during the drawing process were observed.The results show that the oxygen-free copper pipe is drawn by the floating plug in multiple passes,the grains tend to be fibrous along the drawing direction,and the tensile strength and Vickers hardness are continuously improved,but the influence of drawing deformation on the electrical conductivity is relatively small.When the cumulative deformation amount of the oxygen-free copper pipe reaches 75.8%,the tensile strength of the copper pipe is 416.5 MPa,and the problem of pipe breakage is easy to occur if continuing to draw,so the intermediate annealing is required.After deformation of eight drawing passes and one intermediate annealing treatment,the heat pipe of ultra-thin and super-fine in the smartphone with specification ofΦ2 mm×0.08 mm is obtained with the tensile strength of 403.8 MPa,the elongation of 1.78%,the electrical conductivity of 98.85%IACS,the outer diameter tolerance of±0.02 mm and the wall thickness tolerance of±0.01 mm.