Electric heating – Metal heating – By arc
Reexamination Certificate
2000-06-21
2002-03-05
Heinrich, Samuel M. (Department: 1725)
Electric heating
Metal heating
By arc
C219S121750, C219S121810
Reexamination Certificate
active
06353203
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a laser machining device, and more specifically to a laser machining device for drilling, cutting, or marking a material of a printed board, a semiconductor chip or the like such as resin or ceramics.
BACKGROUND ART
As a laser machining device for drilling, cutting, or marking, there has been well known the one having a structure as shown in FIG.
46
.
This laser machining device has a laser oscillator
1
which is a source of a laser beam L, a collimate lens
2
for adjusting a divergence angle of the laser beam, Y-axial and X-axial galvanomirrors
3
and
4
each for deflecting the laser beam L to a required direction based on the rotation angle, a Y-axial galvanoscanner
5
and an X-axial galvanoscanner
6
each for adjusting rotation angles of the Y-axial galvanomirror
3
and X-axial galvanomirror
4
respectively according to a machining program, and a converging lens
7
for introducing and converging the laser beam L deflected by the Y-axial galvanomirror
3
and X-axial galvanomirror
4
.
Wavelength of the laser beam L generated by the laser oscillator
1
varies according to a quality of a work to be machined, but in many cases a carbon oxide gas laser is used as the laser oscillator
1
.
The converging lens
7
is an optical lens capable of deciding a converging position according to the incidence angle of the laser beam, and changes a converging position according to an incidence angle decided under deflection control by the Y-axial galvanomirror
3
and X-axial galvanomirror
4
.
The laser machining device has an XY table device
8
for mounting and positioning of a work W to be machined, and by moving the work W can change the relative position of the work W with respect to the converging lens
7
according to movement of the XY table device
8
along the axes. Laser beam L converged by the converging lens
7
is irradiated onto the work W mounted on the XY table device
8
.
Adjacent to the XY table device
8
, there is provided a vision sensor
9
for detecting a machined position on the work W machined by means of irradiation of the laser beam L.
Connected to the laser machining device is a control unit
10
such as a numerical control unit for driving and controlling the laser oscillator
1
, Y-axial galvanoscanner
5
and X-axial galvanoscanner
6
. In many cases the control unit
10
is a PC-NC having a personal computer as a user interface, and has a machining program with machining positions or conditions for machining described therein previously stored in the personal computer.
Types of machining required in a laser machining device include drilling of a small hole having a diameter in a range from 50 &mgr;m to around 200 &mgr;m, and in this type of machining for drilling a small hole it is necessary to converge a laser beam onto a very small spot having a diameter in a range from 50 &mgr;m to around 200 &mgr;m on the work W to be machined. To achieve this, the converging lens for converging a laser beam onto a work W is used.
A light path of a laser beam outputted from the laser oscillator
1
to the work W has a certain distance, so that the laser beam diverges while propagating this light path and the diameter of the beam becomes larger on the Y-axial galvanomirror
3
and X-axial galvanomirror
4
. To obtain a required diameter for the laser beam, adjustment of the divergence angle of the laser beam is required. To achieve this, the collimate lens
2
is provided in the light path to adjust the beam diameter.
To irradiate the laser beam L onto a required portion of the work W, the Y-axial galvanoscanner
5
and X-axial galvanoscanner
6
are driven to change the rotation angles of the Y-axial galvanomirror
3
and X-axial galvanomirror
4
so as to deflect the laser beam to a required position in a required direction. Coordinates on the work W are unitarily decided according to an incidence angle &thgr; of the deflected laser beam with the converging lens
7
.
In response to a start instruction from an operator or a start signal inputted from the outside the control unit
10
executes machining based on the selected machining program. In this machining program, data for required machining positions are converted into the coordinates of the XY table device
8
as well as into the coordinates (rotation angles) of the galvanoscanners
3
and
4
.
When executing a machining program, the control unit
10
outputs a drive signal according to the machining program so that large movement is executed by means of movement of the XY table device
8
in which many movement strokes can be set, and small movement is executed by means of scan movement of the Y-axial galvanomirror
3
and X-axial galvanomirror
4
each having a high moving speed.
Generally a DC servo motor is used for the Y-axial galvanoscanner
5
and X-axial galvanoscanner
6
, and the technique for providing a position detector or servo control is often employed. Generally the XY table device
8
is driven and controlled by a servo motor using a ball screw.
The Y-axial galvanoscanner
5
and X-axial galvanoscanner
6
can make positioning at a high speed of a round 500 holes/s, and the XY table device
8
can be driven at a speed of 30 m/s. Presently, a positioning precision for the Y-axial galvanoscanner
5
, X-axial galvanoscanner
6
and XY table device
8
can be achieved to a level of around ±20 &mgr;m.
Generally the converging lens
7
is classified as a conversion lens, and is often used as a combination lens called as the f&thgr; lens.
FIG. 47
shows a converging position when the f&thgr; lens is used as the converging lens
7
. With the f&thgr; lens, it is possible to obtain an image height (operational distance) &ohgr; proportional to an incidence angle &thgr; of the laser beam L having passed through the focus position into the f&thgr; lens. It has been known that the following equation is established in this case:
&ohgr;=
f·&thgr;
wherein f indicates a focal length of the f&thgr; lens and &thgr; indicates an incidence angle of the laser beam.
The converging lens
7
gets aberration like in a general optical glass lens, so that it is difficult to maintain the relation of &ohgr;=f·&thgr;. Therefore, in many cases a deviation between the theoretical value and the actual value is measured and this deviation is used as means for correcting an instruction value for a deflection angle of each of the Y-axial galvanoscanner
5
and X-axial galvanoscanner
6
.
In this correction, correction of the converging lens is made for each machining position (x, y) to decide instruction values (x′, y′) for the deflecting devices (Y-axial galvanoscanner
5
, X-axial galvanoscanner
6
). This correction is often made by using an expression for conversion using a matrix, and to decide this expression for conversion, it is possible to cancel such an effect as aberration of a lens at the point of time by updating the expression for conversion used for correction independently from an ordinary machining sequence.
FIG. 48
is a flow chart showing a sequence for correcting and updating the parameters of the converging lens. To correct the aberration of the converging lens, drilling for correction is executed according to an instruction for machining positions having the configuration shown in FIG.
49
and the latticetype pattern shown as shown in
FIG. 50
(step S
611
). However, because of aberration of the converging lens
7
, in most cases the actually machined positions are displaced from the actually instructed lattice points as shown in FIG.
51
.
When the drilling for correction is complete, a position of a machined hole is monitored with the vision sensor
9
, and the coordinates of the machined hole are detected (step S
612
). With such operations a deviation between theoretical positions of the holes and an actually position of the machined holes can be obtained, so that coordinate transformation can be executed to obtain a desired machining position according to the obtained deviation. The coordinate transformation is
Hokodate Toshiyuki
Iwai Yasuhiko
Kurosawa Miki
Nishimae Jun-ichi
Tanaka Kentaro
Heinrich Samuel M.
Mitsubishi Denki & Kabushiki Kaisha
Sughrue & Mion, PLLC
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