The semiconductor laser was used to achieve the transmission welding of polycarbonate (PC) parts. The influences of two kinds of laser absorbers, carbon black (CB) and copper film with carbon black (CWCB), on the weldability of PC parts were analyzed, and the effects of CWCB width on weld morphological characteristics, weld seam deformation, residual stress, and welding strength were further studied. The results show that when CWCB is used as laser absorber instead of CB, the number of bubbles within weld seams is significantly reduced and there occurs obvious deformation of CWCB. The depth and area of deformation increase with the increase of CWCB width. When the CWCB width is 2.5 mm, the depth and area of deformation start to decrease, and the overflow height is stable at 386.32--392.26 μm. In addition, the residual stress and weld width increase as the CWCB width increases. The weld parts have the largest strength of 21.5 MPa when the CWCB width is 1.0 mm, and then the welding strength begins to decrease with the increase of CWCB width.