Method of exposing printed wiring boards having through holes

Details Method of exposing printed wiring boards having through holes Method of exposing printed wiring boards having through holes

1990-06-27

1992-09-15

McCamish, Marion E.

Radiation imagery chemistry: process, composition, or product th

Imaging affecting physical property of radiation sensitive...

Electron beam imaging

430311, 430395, 430942, 430945, G03F 720

Patent

active

051477602

ABSTRACT:
A method of exposing the resist on a printed wiring board having through holes for connecting planar circuit patterns on the plane surfaces of the substrate is disclosed, wherein an electron beam direct writing system is utilized for scanning a converging electron beam as the exposure energy. The electron beam produced by the system enters the opening of the through hole, forming an inclination angle different from 0 degrees and up to 7 degrees with respect to the normal to the opening area of the through hole, such that the resist on the wall surface of the through hole is exposed simultaneously both by the direct and the reflected electron beam. The amount of exposure per unit area of the opening of the through hole may be controlled to 2h/r times the amount of exposure per unit area over the planar surface of the substrate, wherein h and r are the depth and the radius of the through holes, respectively. A reflector plate may be disposed at the bottom opening of the through holes to further enhance the utilization efficiency of the electron beam during through-hole wall surface exposure.

REFERENCES:
patent: 4612275 (1986-09-01), Gregor
patent: 4883571 (1989-11-01), Kondo et al.
Kawazu et al., "Electron Beam Direct Writing Technology For Printed Wiring Board", IEEE/CHMT '89 IEMT Symposium, 1989, pp. 246-250.
Technical Report of Mitsubishi Electric Corporation, vol. 63, Nov. 2, 1989, pp. 75-78, by Hoshino et al.

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