Seigo Hiramoto

VACUUM VAPOR DEPOSITION PROCESS FOR CERAMICS DEVELOPMENT OF THE VACUUM VAPOR DEPOSITION PROCESS FOR CERAMICS BY CO2 LASER

Abstract The vacuum vapor deposition process using a CO2lase; has been studied (or producing high adhesion ceramic films on various materials. Deposition of aluminum oxide and silicon oxide films with adhesion strengths above 50 MPa on stainless steel was achieved at high deposition rates with substrate heating, For silicon oxide films, addition of a moderate oxygen supply allowed deposition of highly adherent films at lower substrate temperatures. Adhesion strengths above 50 MPa were estimated at a substrate temperature of 470°K and an oxygen flow rate of 1.9 x 10-7 m3/s, in spitof the high deposition rate of 30 nm/s

Development of laser marking for IC packages

Laser marking is expected to apply to the production of IC packages, which are made of black composite resin. YAG laser and CO2 laser can be used for marking. It is considered that YAG laser marks are clearer than CO2 laser marks generally. But the difference of the visibility between YAG laser marks and CO2 laser marks is not obvious at present. Therefore, the effect of the wavelength of lasers on the visibility of the marks is investigated.In the experiment, the specimens were marked by YAG laser and CO2 laser irradiation. And the visibilities, the removed volumes and the microstructures of marked specimens were evaluated with an optical microscope, a surface profiling instrument and SEM. The characteristics of the absorbed laser energy of specimens were evaluated with a spectro-photometer.The YAG laser mark was clearer than the CO2 laser mark; the former was light brown and the latter was dark brown. The visibility of the laser marks did not depend on the removed volume, but depended on the contrast between irradiated region and other region. From the microstructures of the marks, it was deduced that the matrix resin was decolorized by YAG laser irradiation.Laser marking is expected to apply to the production of IC packages, which are made of black composite resin. YAG laser and CO2 laser can be used for marking. It is considered that YAG laser marks are clearer than CO2 laser marks generally. But the difference of the visibility between YAG laser marks and CO2 laser marks is not obvious at present. Therefore, the effect of the wavelength of lasers on the visibility of the marks is investigated.In the experiment, the specimens were marked by YAG laser and CO2 laser irradiation. And the visibilities, the removed volumes and the microstructures of marked specimens were evaluated with an optical microscope, a surface profiling instrument and SEM. The characteristics of the absorbed laser energy of specimens were evaluated with a spectro-photometer.The YAG laser mark was clearer than the CO2 laser mark; the former was light brown and the latter was dark brown. The visibility of the laser marks did not depend on the removed volume, but depended on the contrast be...

Laser beam machining.

1) M. E. Prise, et al.: Appl. Opt. 30 (1991) 2287. 2) A. Huang: Optical Computing, 1989, Technical Digest Series, 9 (1989) 198. 3) A. C. Walker, et al.: Optical Computing, 1991 Technical Digest Series, 6 (1991) 199. 4) F. Kiamilev, et al.: Opt. Eng. 28 (1989) 396. 5) K. S. Huang, et al.: Proc. SPIE 963 (1988) 687. 6) A. V. Krishnamoorthy, et al.: Optical Computing, 1991 Technical Degest Series 6 (1991) 244. 7) J. Tanida, et al.: Optical Computing, 1992 Technical Digest, 29C1 (1992).

Laser drilling by high peak pulsed CO2 laser (LDHPCL)

Control of input heat to reduce the incidence of recast layers and cracks formed during laser processing of non-metallic materials was studied.Suitable ranges of pulse parameters including peak power, pulse duration, and frequency for non-metallic materials were determined using theoretical investigations. Based on the results of this experiment, a high peak pulsed CO2 laser which output pulses of tens of microseconds using the TEMoo beam mode and 5kW of peak power, was developed. This high peak pulsed CO2 laser was used to study the fundamentals of laser drilling of ceramics and printed wiring boards (PWBs).In the case of ceramics, recast layers including microcracks on the side walls of drilled holes were caused by conventional CO2 lasers. Use of the high peak pulsed CO2 laser reduced the size of recast layers. Furthermore, the effect of the beam-plasma interaction on the hole shape was examined. The results revealed that in air, plasma plume induced beam scattering increased hole diameter. It was also found that decreasing the pulse duration could limit the effects of beam scattering.Conventional laser drilling of PWBs results in glass fiber protrusions. The high peak pulsed CO2 laser was found to decrease the amount of glass fiber protrusions. It was discovered that lowering the pulse frequency successfully reduced heat accumulation; a major cause of glass fiber protrusions. It was possible to fabricate high aspect ratio (=10) holes in epoxy-glass PWBs without glass fiber protrusions using the high peak pulsed CO2 laser set a short pulse durations and low frequencies.Control of input heat to reduce the incidence of recast layers and cracks formed during laser processing of non-metallic materials was studied.Suitable ranges of pulse parameters including peak power, pulse duration, and frequency for non-metallic materials were determined using theoretical investigations. Based on the results of this experiment, a high peak pulsed CO2 laser which output pulses of tens of microseconds using the TEMoo beam mode and 5kW of peak power, was developed. This high peak pulsed CO2 laser was used to study the fundamentals of laser drilling of ceramics and printed wiring boards (PWBs).In the case of ceramics, recast layers including microcracks on the side walls of drilled holes were caused by conventional CO2 lasers. Use of the high peak pulsed CO2 laser reduced the size of recast layers. Furthermore, the effect of the beam-plasma interaction on the hole shape was examined. The results revealed that in air, plasma plume induced beam scattering increased hole diameter. It was also ...

Formation of alumina film by laser PVD

Laser PVD of alumina ceramics on Ni and other various metallic substrates was conducted by using cw Nd:YAG laser heat source to clarify the effect of PVD conditions on deposition rate and hardness of a film as well as the effects of substrate materials and thermal expansions on the adhesion, hardness and cracking susceptibility of the film. Optimum PVD conditions were obtained concerning laser power, target-substrate distance, chamber pressure and substrate temperature for the formation of a better adhesive, crack-free, hard alumina film. According to the degree of bent deformation of special thin substrates, higher stress was induced in the film due to the difference of thermal expansion coefficient between film and substrate at higher substrate temperature. Tension was induced in the film on W and Mo substrate, while compression took place in the film on Ta, Ti, Ni and Cu. Cracks were present in the films on W, Ni and Cu at high substrate temperature. This reason was attributed to such higher tension and much higher compression.Laser PVD of alumina ceramics on Ni and other various metallic substrates was conducted by using cw Nd:YAG laser heat source to clarify the effect of PVD conditions on deposition rate and hardness of a film as well as the effects of substrate materials and thermal expansions on the adhesion, hardness and cracking susceptibility of the film. Optimum PVD conditions were obtained concerning laser power, target-substrate distance, chamber pressure and substrate temperature for the formation of a better adhesive, crack-free, hard alumina film. According to the degree of bent deformation of special thin substrates, higher stress was induced in the film due to the difference of thermal expansion coefficient between film and substrate at higher substrate temperature. Tension was induced in the film on W and Mo substrate, while compression took place in the film on Ta, Ti, Ni and Cu. Cracks were present in the films on W, Ni and Cu at high substrate temperature. This reason was attributed to such higher tension an...

Basic study on laser physical vapour deposition of ceramics

Abstract A basic study on the laser physical vapour deposition (PVD) of ceramics was conducted using a continuous wave (CW) Nd:YAG laser. Aluminaceramic and nickel plates were used as target and substrate materials respectively. The experiment was carried out over a wide range of PVD conditions, i.e. substrate temperature up to 1100 K and pressures up to 6.5 × 10 -4 Pa. A Knoop hardness (HK) tester and a scratch tester were used to evaluate the deposited film. Phase content, microstructure and chemical composition were examined by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. Results showed that a crystallized film with a hardness HK of 30 GPa or greater could be obtained by providing a suitable combination of PVD conditions, i.e. pressure and substrate temperature.

Development of automatic beam focus detecting system for electron beam welding.

In electron beam welding, it is very important to set focal position of beam on work piece appropriately. However, it is very difficult to set one accurately in case of complex joint geometry.New beam focus detecting system have been developed as part of intelligent welding system for electron beam welding.When electron beam is irradiated on work poece, backscattered electron, thermoelectron, secondary electron, ion or X-ray emitted from work piece are observed. Among these, thermoelectron is much affected with surface condition of a work piece. That is, as soon as the surface melted, thermoelectron increased rapidly.The results obtained are as follows.1. In case that the condition of beam convergency on work piece is shifted from out of focus to in focus, signal of thermoelectron shows peak value when beam focal position coincide with the surface of work piece.2. It is possible to obtain high S/N ratio by employing positive collector bias by which thermoelectron gathered easily to the collector.3. The detecting accuracy is within ±1% in the case that ab factor is 1.0.

A New Die-Manufacturing Process Suitable for FMS of Press Forming in Large Variety Production

Recently, various softwares and hardwares have been developed to promote Flexible Manufacturing Systems of press forming. For press dies, however, how to simplify die-manufacturing has been the most important subject in promotion of FMS.