Electric heating – Metal heating – By arc
Reexamination Certificate
2001-06-28
2004-08-03
Stoner, Kiley (Department: 1725)
Electric heating
Metal heating
By arc
C219S121790, C219S121800
Reexamination Certificate
active
06770843
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and method for drilling holes in electronic circuit substrates using laser light.
FIG. 7
schematically shows the construction of a known laser processing apparatus, such as a CO
2
gas laser machining apparatus. Laser light
102
emitted from a laser oscillator
101
is guided onto a workpiece
107
for forming micropores therein. A galvanometer
104
swings as it reflects received laser light
102
onto an f&thgr; lens
105
in a scanning manner. Thereupon, the f&thgr; lens
105
converges the incident rays to form a focus spot
106
at a predetermined location on the workpiece
107
.
In general, laser light emitted from such laser oscillator contains light rays of various wavelengths and of various intensities. For achieving a high degree of precision in laser machining, the presence of light of various differing wavelengths presents a problem, particularly when employing an f&thgr; lens, which is highly liable to chromatic aberration.
That is, when the laser light, which contains a plurality of light rays having different wavelengths &lgr;
1
, &lgr;
2
, &lgr;
3
, is emitted toward the f&thgr; lens, chromatic aberration tends to occur because of the differences in wavelength of the laser light, since the refraction index of the f&thgr; lens differs depending on the wavelength. As a result, a plurality of focus spots are respectively formed by the discrete light rays of various wavelengths, as indicated by reference designators f
1
, f
2
, and f
3
in FIG.
7
. This is particularly so when the light incident position is spaced from the center of the f&thgr; lens. The formation of a plurality of focus spots f
1
, f
2
, and f
3
leads to unfavorable drilling results such as oval holes or a plurality of separate holes.
SUMMARY OF THE INVENTION
The present invention has been devised in light of the above-described problems encountered by the prior art, and it is an object of the invention to provide an improved laser processing method and an apparatus therefor, with which the formation of a plurality of or oval focus spots is inhibited, and drilling of favorable shapes is ensured.
A laser processing apparatus according to the invention includes:
a laser oscillator for emitting laser light;
an f&thgr; lens positioned relative to the laser oscillator for converging the emitted laser light onto a workpiece; and
a wavelength selector interposed between the laser oscillator and the f&thgr; lens for separating a light ray having a specified wavelength out of the laser light.
By providing the wavelength selector between the laser oscillator and the f&thgr; lens, a light ray having a specified wavelength is singled out from the laser light. The single light ray converged by the f&thgr; lens forms only a single focus spot. Thus adverse effects of chromatic aberration caused by the f&thgr; lens are eliminated, whereby the formation of deformed focus spots or a plurality of focus spots is inhibited, and the machining precision is enhanced.
These and other objects and characteristics of the present invention will become further clear from the following description with reference to the accompanying drawings.
REFERENCES:
patent: 3743383 (1973-07-01), Giallorenzi
patent: 4832469 (1989-05-01), Noguchi et al.
patent: 5528612 (1996-06-01), Scheps et al.
patent: 5670069 (1997-09-01), Nakai et al.
patent: 5914978 (1999-06-01), Welch et al.
patent: 5969335 (1999-10-01), Karasaki
Muneyuki Ken
Nakai Izuru
Okada Toshiharu
Yuki Haruhiro
Greenblum & Bernstein P.L.C.
Stoner Kiley
Tran Len
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