Jozef Wendland

Dual-axis beam correction for an array of single-mode diode laser emitters using a laser-written custom phase-plate

A single optical component for a diode laser bar combines fast-axis smile and lens error correction with slow-axis collimation. Produced by laser-machining/polishing, it provides 0.9 mm focal length, 200 microm pitch slow-axis collimation on the same surface that corrects fast-axis errors. Custom fabrication enables fill-factor optimization for the 49 single-mode beams and gives parallel collimation with rms pointing errors of 3% and 6% of the far-field divergence for the fast- and slow-axis array respectively. Sub-micron pitch mismatch between the slow-axis lens and emitter arrays, and beam pointing changes by thermal expansion of the laser bar are detected.

CO2 laser processing of alumina (Al2O3) printed circuit board substrates

We report the results of an investigation of the laser-material interaction processes involved in laser drilling of alumina, through the use of an enhanced peak power (2.5 kW) CO/sub 2/ laser and novel temporal pulse formats. Peak power was varied from 30 W to 2 kW for pulses of constant energy to observe the effect produced on scribe depth. High-speed videography of hole formation has been combined with microscopic analysis to investigate the key processes involved in laser processing of alumina. Plasma screening was observed for short, high peak power laser pulses, and optimal scribing was achieved in the weakly plasma absorbing regime. A new processing technique for scribing alumina has been developed, which exploits the fast response of the laser to produce novel temporal pulse shapes, which can be modified to generate cleaner holes. Scribe speeds of up to 280 mm/spl middot/s/sup -1/ were obtained for scribe holes >200 /spl mu/m deep and 150 /spl mu/m apart, with no material plugging the hole, in 0.635-mm-thick 96% alumina.

CO/sub 2/ laser processing of alumina (Al/sub 2/O/sub 3/) printed circuit board substrates

We report the results of an investigation of the laser-material interaction processes involved in laser drilling of alumina, through the use of an enhanced peak power (2.5 kW) CO/sub 2/ laser and novel temporal pulse formats. Peak power was varied from 30 W to 2 kW for pulses of constant energy to observe the effect produced on scribe depth. High-speed videography of hole formation has been combined with microscopic analysis to investigate the key processes involved in laser processing of alumina. Plasma screening was observed for short, high peak power laser pulses, and optimal scribing was achieved in the weakly plasma absorbing regime. A new processing technique for scribing alumina has been developed, which exploits the fast response of the laser to produce novel temporal pulse shapes, which can be modified to generate cleaner holes. Scribe speeds of up to 280 mm/spl middot/s/sup -1/ were obtained for scribe holes >200 /spl mu/m deep and 150 /spl mu/m apart, with no material plugging the hole, in 0.635-mm-thick 96% alumina.

31.3: Rapid Laser Patterning of ITO on Glass for Next Generation Plasma Display Panel Manufacture

Rapid Laser Patterning (RLP) of ITO on glass offers a cost effective alternative to wet-etch lithography in the manufacture of PDPs. It is demonstrated that RLP can effectively pattern ITO to industrial standards. It is also shown that the process is rapid and has major cost benefits vs. lithography.

Enhanced peak power CO2 laser processing of PCB materials

Laser drilling has become a common processing step in the fabrication of printed circuit boards (PCBs). For this work, a recently developed enhanced peak power CO2 laser (~2.5 kW peak power, 200W average) or ultra-super pulse (USP) laser is used to drill alumina and copper coated dielectric laminate materials. The higher peak power and faster response times (than conventional CO2 lasers) produced by the USP laser are used to produce high speed alumina laser scribing and copper coated laminate microvia drilling processes. Alumina is a common PCB material used for applications, where its resistance to mechanical and thermal stresses is required. Here we present a comprehensive study of the melt eject mechanisms and recast formation to optimise the speed and quality of alumina laser scribing. Scribe speeds of up to 320 mms-1 (1.8 times current scribe rate) have been achieved using novel temporal pulse shapes unique to the USP laser. Also presented is the microvia drilling process of copper dielectric laminates, where the multi-level configuration presents different optical and thermal properties complicating their simultaneous laser ablation. In our experiments the USP laser has been used to drill standard thickness copper films (up to 50 μm thick) in a single shot. This investigation concentrates on understanding the mechanisms that determine the dielectric undercut dimensions.

Rapid laser patterning versus wet-etch lithography for flat panel display manufacture: A technical & commercial comparison

Rapid Laser Patterning (RLP) of ITO thin films on glass offers a credible industrial alternative to wet-etch lithography for the manufacture of Flat Panel Displays – particularly for Plasma Displays. For any disruptive technology it is necessary to compare and contrast it with the existing manufacturing technique so that end users can make an informed decision as to its relative merits – both technical and commercial.Both processes are compared empirically and it is demonstrated that RLP offers benefits in terms of edge resolution, taper and is less prone to residue. Furthermore a commercial cost model is generated based on real capital and operational cost data. This model suggests that RLP can offer cost savings in the order of tens of millions of dollars for a single production line over a three year depreciation period.Rapid Laser Patterning (RLP) of ITO thin films on glass offers a credible industrial alternative to wet-etch lithography for the manufacture of Flat Panel Displays – particularly for Plasma Displays. For any disruptive technology it is necessary to compare and contrast it with the existing manufacturing technique so that end users can make an informed decision as to its relative merits – both technical and commercial.Both processes are compared empirically and it is demonstrated that RLP offers benefits in terms of edge resolution, taper and is less prone to residue. Furthermore a commercial cost model is generated based on real capital and operational cost data. This model suggests that RLP can offer cost savings in the order of tens of millions of dollars for a single production line over a three year depreciation period.

CO 2 laser processing of alumina (Al 2 O 3 ) printed circuit board substrates

We report the results of an investigation of the laser-material interaction processes involved in laser drilling of alumina, through the use of an enhanced peak power (2.5 kW) CO/sub 2/ laser and novel temporal pulse formats. Peak power was varied from 30 W to 2 kW for pulses of constant energy to observe the effect produced on scribe depth. High-speed videography of hole formation has been combined with microscopic analysis to investigate the key processes involved in laser processing of alumina. Plasma screening was observed for short, high peak power laser pulses, and optimal scribing was achieved in the weakly plasma absorbing regime. A new processing technique for scribing alumina has been developed, which exploits the fast response of the laser to produce novel temporal pulse shapes, which can be modified to generate cleaner holes. Scribe speeds of up to 280 mm/spl middot/s/sup -1/ were obtained for scribe holes >200 /spl mu/m deep and 150 /spl mu/m apart, with no material plugging the hole, in 0.635-mm-thick 96% alumina.

Single-pulse microvia drilling of resin-coated copper substrates using an enhanced peak power planar waveguide CO2 laser

CO2 laser drilling of the resin coated copper (RCC) layers of laminated circuit boards has been investigated at different fluence levels. The threshold fluence for copper layer drilling is found to be 570 Jcm-2 for 5μm and 1500 Jcm-2 for 12μm copper thickness, using laser pulses in the 10 μs and 20 μs FWHM respectively. Undercut in the resin layer is found to primarily depend on the amount of excess energy in the pulse tail. Methods to reduce the pulse decay time have been investigated, giving smaller diameter breakthrough holes close to threshold, which should aid the control of hole drilling in RCC. High-speed videography has been used to verify the observations of post-processing analysis.

Operation of a cw 14C16O2 laser in the 12 μm spectral region

Abstract We report the cw operation of a sealed-off dc discharge excited carbon dioxide laser with a novel variation to the conventional grating-tuned resonator arrangement, which permits the achievement of useful laser power output levels in the wavelength range of 11.1–12.1 μm, using the 14 C 16 O 2 isotope in the laser gas mixture.

High power mid infrared operation of the atomic xenon laser

We report high power cw operation of a slab waveguide atomic xenon laser in a spectral region of low atmospheric absorption. Using transverse radio frequency discharge excitation at 49 MHz and a hybrid waveguide-unstable resonator, with a sharp band edge on the reflectivity versus wavelength curve of the laser mirrors, 50 mW was obtained on the 3.869 μm transition and 210 mW on the 3.895 μm line.