Hidenobu Murakami

Electron beam direct writing technology for printed wiring board

An electron-beam lithography system has been developed which can write electric circuit patterns directly on printed wiring boards from computer-aided design data without making the master and working film masks which are necessary for conventional photolithography. The electron beam is focused to 34 mu m in diameter at an accelerating voltage of 60 kV. The sensitivity of an electrodeposited photoresist to electron-beam exposure is investigated. It is shown that the photoresist is very sensitive to the electron beam and has a threshold dosage of 0.2 mu C/cm/sup 2/. The spatial contours of equienergy density deposited by the electron beam in a 20- mu m-thick resist-copper substrate configuration have been calculated with a Monte Carlo computer method. The geometry of the resist patterns is determined according to the contour line corresponding to about 6*10/sup 18/ eV/cm/sup 3/. It has been confirmed that fine patterns with linewidths less than 100 mu m can be obtained and that this technology is efficient for meeting the constantly growing demand for greater density and shorter turnaround.<<ETX>>

Large area electron beam direct imaging technology for printed wiring boards

An electron beam direct imaging system that can image electric circuit patterns directly on printed wiring boards (PWBs) from computer-aided design (CAD) data without using film masks has been developed. The system realizes beam deflection over a large field of 100 mm*100 mm. The deflection field can be imaged in less than 1 s with an accuracy of better than +or-30 mu m. The maximum deflection speed is 254 m/s, and the beam diameter in full width at half maximum is 40 mu m. This technology can use the same kinds of resists as those for conventional photolithography. It was shown that fine patterns with line widths less than 100 mu m can be imaged for PWBs 340 mm*400 mm in size by stitching deflection fields.<<ETX>>

Study on high-speed beam deflection for electron beam machining.

A frequency band required for an oscillation technique on an electron beam welding was discussed by analyzing vibration frequencies of molten metal. Lower limits of beam scanning velocity not melting surfaces of work-pieces were also discussed by calculating temperature rise. A high-speed beam deflecting device to satisfy above conditions was developed and some applications of high-speed beam deflection were studied.The conclusions obtained are summarized as follows:(1) The vibration frequencies of the molten metal are less than 10 kHz and a beam oscillation with higher frequencies than 10 kHz is necessary to control distribution of an input power to a work-piece regardless of molten metal vibration.(2) A beam scanning velocity of more than 10000 m/min is required not to melt a steel surface for a beam power of 10 kW(3) A cutoff frequency of 60 kHz (-3dB) in small signal region and a maximum scanning velocity of 23000 m/min (deflection distance 300 nun) are realized using a deflecting device newly developed.(4) The high-speed deflection technique is very effective for the new-field of electron beam application such as marking, patterning, simultaneous multi-beam welding, surface hardening, and so forth.

Study on weld-line detection for electron beam welding - Fundamental characteristics of weld-line detection by X-ray sensor and detection signal processing.

A reliable method of weld-line detection for electron beam welding has been developed by incorporating semiconductor X-ray sensor and signal processor.The fundamental characteristics of weld-line detection and the signal processing to eliminate the noise component are studied. The sensing methods of X-ray and scattered electrons are compared under the condition of practical use.The conclusion obtained are summarized as follows:(1) The X-ray sensing method is very reliable, comparing with the scattered electron method, because of its durability against metal vapours and sputters, and its complete shielding property against an electromagnetic noise.(2) The processing of the weld-line signal, such as a time averaging, is very effective for high resolving power, because the weld-line detector is used in the environment of high noise level caused by high-frequency inverters, power contactors, and so forth.