With an increasing demand for higher volume production of microelectronics components and an accompanying decrease in feature sizes, mechanical techniques such as saw cutting or mechanical drilling appear to approach their practical limits. Recent developments in UV lasers and in particular diode-pumped solid-state (DPSS) lasers provide unique manufacturing advantages for certain applications such as high aspect ratio laser microdrilling of guide plates for vertical probe card manufacturing.
One of the main challenges for high density probing with vertical probe cards in semiconductor manufacturing is the cost effective production of these complex devices and in particular drilling reliably large numbers of high aspect ratio vias in guide plates for the accurate positioning of the pin contacts without compromising hole quality or drilling speed. Lasers are ideal for this process and this paper presents new data on high speed laser drilling of vias in polymer and ceramic plates. High average power frequency converted q-switched UV DPSS lasers (355nm) operating in repetition frequency between 1Hz-100kHz are used in direct laser writing format and are shown to compare well with the established copper vapour lasers (511nm). We describe how lasers can be used to produce circular and non-circular parallel holes, and tapered holes for this application.
The combination of short laser wavelength, nanosecond duration laser pulses with excellent pulse-to-pulse stability provide the necessary high laser intensities on target for efficient laser drilling. It is shown that no cracking and debris free surfaces can be achieved with carefully optimised laser micromachining using these lasers.
