While applications such as drilling μ-vias and laser direct imaging have been well established in the electronics industry, the mobile device industry’s push for miniaturization is generating new demands for packaging technologies that allow for further reduction in feature size while reducing manufacturing cost. CO lasers have recently become available and their shorter wavelength allows for a smaller focus and drilling hole diameters down to 25μm whilst keeping the cost similar to CO2 lasers. Similarly, nanosecond UV lasers have gained significantly in power, become more reliable and lower in cost. On a separate front, the cost of ownership reduction for Excimer lasers has made this class of lasers attractive for structuring redistribution layers of IC substrates with feature sizes down to 2μm. Improvements in reliability and lower up-front cost for picosecond lasers is enabling applications that previously were only cost effective with mechanical means or long-pulsed lasers. We can now span the gamut from 100μm to 2μm for via drilling and can cost effectively structure redistribution layers with lasers instead of UV lamps or singulate packages with picosecond lasers.
Laser Micromachining is well established in industry. Depending on the application lasers with pulse length from μseconds to femtoseconds and wavelengths from 1064nm and its harmonics up to 5μm or 10.6μm are used. Ultrafast laser machining using pulses with pico or femtosecond duration pulses is gaining traction, as it offers very precise processing of materials with low thermal impact. Large-scale industrial ultrafast laser applications show that the market can be divided into various sub segments. One set of applications demand low power around 10W, compact footprint and are extremely sensitive to the laser price whilst still demanding 10ps or shorter laser pulses. A second set of applications are very power hungry and only become economically feasible for large scale deployments at power levels in the 100+W class. There is also a growing demand for applications requiring fs-laser pulses. In our presentation we would like to describe these sub segments by using selected applications from the automotive and electronics industry e.g. drilling of gas/diesel injection nozzles, dicing of LED substrates. We close the presentation with an outlook to micromachining applications e.g. glass cutting and foil processing with unique new CO lasers emitting 5μm laser wavelength.
We report on the recent progress in the design and development of completely monolithic linearly-polarized pulsed
fiber amplifiers seeded by Q-switched fiber laser oscillators. We demonstrate near diffraction limited beam quality with
~ 20 kW peak power (1mJ pulse energy, ~ 45 nsec) pulses and an average power ~ 20 W at 20 kHz repetition rate with
linearly polarized (> 17dB PER) output from a simple MOPA design. The laser produces spectrally narrow pulses with
~ 0.5 nm linewidth centered at 1064nm, suitable for various non-linear applications including generation of visible and
UV light. The simple MOPA design consists of a monolithic fiber amplifier based on an optimized coil of polarization
maintaining large mode area (PM-LMA) fiber with 30 &mgr;m core and low power Q-switched fiber oscillator. Excellent
output beam quality is achieved through the mode selectivity of the coiled PM-LMA fiber in the amplifier stage. Such
compact and robust fiber lasers are suitable for a variety of applications, such as nonlinear wavelength conversion
processes using a variety of nonlinear materials, laser radars, etc.
During the last decade, diode-pumped TEM00 mode solid state lasers have gained widespread application in micromachining of dielectrics and metals. Commercial systems with output powers of up to 40W at 1064nm, 20W at 532nm, 15W at 355nm and 2W at 266nm, repetition rates of up to 400kHz and pulse durations between 10ns and 100ns are now being used in numerous micromachining applications. In addition, industrial applications of modelocked lasers are starting to emerge. This paper will give an overview of the state-of the art of diode-pumped TEM00 mode solid state lasers and their applications in micromachining.