A study of laser etching and cutting PCB boards by 355nm DPSS UV laser

During the last decade, diode-pumped solid state lasers (DPSSL) have gained wider application in industry, of which most of the lasers’ wavelengths are in the ranges 1064nm and 532nm. With the development of DPSSL, shorter wavelength laser such as UV laser is needed to etch the materials in order to get the higher etching depth or precision. However, there are few reports about the comparison for micro machining between UV laser and the infrared laser. In this paper, a 355nm Nd:YVO₄ laser with output power of 8W, repetition rates of 100kHz, pulse duration of 25ns is used for etching the copper clad laminate (CCL) and flexible printed circuit (FPC). The effect of the laser processing parameters such as laser power, single pulse energy, repetition rate and laser scanning speed on the microstructure are studied in detail. By comparing 1064nm laser and 355nm UV laser, the experimental results demonstrated that UV laser processing has higher precision and causes less thermal effect, as copper, PI and epoxy has higher absorptivity for this laser. Nevertheless, the significant benefit for IR laser is that it brings about less damage to PI or epoxy substrates, which makes it fit for the ablation of the copper layer. On the other hand, the 355nm UV laser is fit for the cutting process of the PCB boards because it can make the facile separation of thick polymer substrates quickly.