Nanosecond pulsed laser processing circuits on the copper clad polyimide

Abstract

Precision processing of miniaturised circuits on the surface of three-dimensional (3-D) structure is of great importance for the telecommunication equipment. Laser micro-machining technologies have led the way in the development of innovative solutions in manufacturing high-accuracy circuits. In this paper, fine strip-line of planar helical antenna on the copper clad polyimide (CCPI) is fabricated based on the application of nanosecond pulse laser. In order to obtain the optimised processing parameters for planar helical antenna, ablation experiments of single grooves are performed and the effect of process parameters, such as laser wavelength, single pulse energy density, repetition frequency, scanning speed, laser spot overlap coefficient and milling times, are quantitively analysed. And the strip-line of planar helical antenna is processed under the optimised condition (laser single pulse energy density is 25 J/cm2, frequency is 30 kHz, laser spot overlap coefficient is 0.9, and milling times is 1). Experimental results indicate that the minimum width of micro-strip can reach 50 μm, and form error of strip-line edge processed by nanosecond pulse laser is less than ±10 μm, which could match the geometric accuracy requirement of the micro-strip antenna.