JP2001085765A - Optical working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical working machine, capable of satisfactorily optically machining an optical work, composed of two or more laminated materials which have different optical working characteristics. SOLUTION: In this optical working machine for optically machining a work 11 by irradiating a pattern on a mask 9, with a light beam from optical source means and projecting the patter on the work through a projection lens 10, a light beam from an optical source means is a beam composed of combined light beams from a first and second optical source means 1, 2 which emit pulse lights of mutually different oscillation times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical processing machine for forming an opening such as a hole in a workpiece by using coherent light such as a laser beam or a harmonic thereof. This is suitable when the workpieces are collectively processed at the same time.

[0002]

2. Description of the Related Art Conventionally, laser processing for making a hole in a workpiece by using a laser beam has been frequently used as a method capable of performing non-contact and precise processing.

FIG. 7 is a schematic view of a main part of a conventional optical processing machine using a laser beam. FIG. 1 shows an optical processing machine of an ink-jet printer that collectively forms discharge holes (nozzles) on an ink discharge hole array plate (orifice plate).

In FIG. 1, reference numeral 401 denotes light source means;
For example, coherent light such as an excimer laser or a YAG laser harmonic is oscillated, and its oscillation time width (pulse width) is usually about 5 to 100 nsec.

[0005] 402 splits and combines coherent light,
An illumination optical system that generates a uniform, required spread light beam and illuminates the surface to be irradiated, 403 is a mask having a pattern to be projected on the surface of the workpiece, and the pattern of the mask 403 depends on the projection magnification. It has a large size.

Reference numeral 404 denotes a projection lens for reducing and projecting the pattern image of the mask 403 onto a workpiece 405; 405, a material (workpiece) to be processed; and 406, for observing and controlling the position of the workpiece 405 and the processing status. Image processing apparatus.

In FIG. 7, the coherent light emitted from the light source means 401 is guided to an illumination optical system 402, and is converted into a light beam having a predetermined spread angle and uniformity by a mask 403.
To illuminate.

When a hole is to be formed in the mask 403, a necessary number of patterns to be transmitted are formed at necessary hole positions and hole sizes, and according to the projection magnification of the projection lens 404, the pattern to be processed is formed. , Usually several times to several tens times the transmission shape.

The light cut out by the pattern of the mask 403 is reduced and projected by the projection lens 404, reaches a material (workpiece) 405, and processes the material 405 by ablation or heat by the energy.

[0010] As another laser processing machine, Japanese Patent Application Laid-Open No. 9-85 is disclosed.
No. 475 proposes an optical processing machine using a laser beam having a high peak power of p seconds or less.

[0011]

In recent years, in optical processing using laser light, different materials such as plastic and metal are layered as processing objects with the aim of improving processing accuracy and improving product characteristics. Things are increasing.

For example, there are a multilayer printed circuit board, plastic or glass having a surface coated with metal, and silicon having a protective layer. Further, a multilayer film, a functionally graded material, and the like are also included in the category.

As an example of the optical processing, the following characteristics can be given in the case of a plastic manufactured by depositing or plating a metal protective layer on the surface.

(A-1) Due to the protection of the metal, even if it is used for a contact portion or a sliding portion, it is scarcely damaged or changes with time.

(A-2) By combining the hydrophilic property of metal and the water-breaking property of plastic, waterproofing, dew condensation prevention,
It has the effect of preventing dirt.

(A-3) Since it has high thermal conductivity and a large heat radiation effect, plastic parts can be used also in a region where thermal deformation has conventionally been a problem.

(A-4) Since the thin layer of metal has a high optical processing threshold value, it has processing characteristics with large non-linearity, and the edge shape of the processing result is higher than the optical resolution, so that a sharp hole contour is obtained. be able to.

(A-5) The metal of the protective layer can be joined by soldering or the like by a self-adjustment effect between the hole and the parts at the time of joining without adjusting the position, and a functional assembly can be performed. Can be.

(A-6) By giving a glossiness and a profound feeling which plastics do not have, it is possible to provide a wide range of product design effects.

On the other hand, when laser processing these composite materials, there are the following problems.

(A-1) When the energy suitable for processing is large, such as when using metal and plastic together, and when different materials are used, the output energy of the laser device or the processing energy may not be fully adjusted by the light amount variable filter. Many,
Also, as for the adjustment range, it is often necessary to prepare a laser whose laser output standard is very redundant.

(A-2) Since the processing threshold value is greatly different between the two materials, it is difficult to match the tapered shape by processing only with the strength. For example, the internal shape of the hole when drilling is made uniform. It is difficult to finish.

As an example, a workpiece in which gold is deposited as a protective layer on a plastic surface will be described with reference to FIG.

FIG. 6 shows a conceptual diagram of optical processing. Three
01 is coherent light to be irradiated, and 302 is gold, for example, which is an upper surface protective layer of a processing target (workpiece).

Reference numeral 303 denotes a plastic occupying a bulk portion to be processed, and reference numeral 304 denotes a lower surface protective layer to be processed.

The energy E of the coherent light 301 is
As shown in FIG. 6B, if the processing threshold value Eth of the gold 301 is lower than the processing threshold value Eth, the processing does not proceed at all, and at a certain point, the plastic portion 302 is melted and carbonized, and the processing is not successful.

The energy E of the coherent light 301 is
As shown in FIG. 6 (C), when the processing threshold value of the gold 302 is around Eth, the processing uniformity of the gold 302 is poor, so that a hole having a good shape cannot be obtained.

When the energy E of the coherent light 301 is set to exceed the processing threshold value Eth of the gold 302 by several times as shown in FIG. 6D, the processing uniformity of the gold 302 is improved. Since the processing threshold value is several tens of times the processing threshold value of the plastic 303, the processing characteristics of the plastic 303 deteriorate, resulting in undesirable non-uniformity such as melting of edges.

After the number of shots which seems to have penetrated the coherent light 301 through the upper protective layer 302, the energy of the coherent light 301 is reduced by some means, and the coherent light 301 is processed to the lower protective layer 303 in accordance with the processing energy of the plastic 302. However, there is a case where the processing energy is increased again after reaching the lower surface protection layer 303.

Although this method is possible in principle, it is quite difficult to control the irradiation time accurately due to the influence of the subtle unevenness of the thickness of the coherent light 301 and the plastic 303.

According to the present invention, when an optical workpiece is formed by using a laser beam, a workpiece having a characteristic having a different relationship between energy and processing characteristics can be obtained without greatly changing the processing conditions and the total processing energy. An object of the present invention is to provide an optical processing machine capable of performing stable processing.

[0032]

According to a first aspect of the present invention, a processing machine illuminates a pattern on a mask with a light beam from a light source, and projects the pattern on the mask onto a workpiece by a projection lens. In an optical processing machine for optically processing a workpiece, a light beam from the light source unit is a combined light beam obtained by combining light beams from two light source units of first and second light source units that emit pulse lights having different oscillation times. It is characterized by being.

According to a second aspect of the present invention, an optical processing machine illuminates a pattern on a mask with a light beam from a light source means, projects the pattern on the mask onto a workpiece by a projection lens, and optically processes the workpiece. The light beam from the light source means emits coherent light having an oscillation time of 1 ns or less, and emits coherent light having an oscillation time longer than the oscillation time of the first light source means. And a combined light beam obtained by combining light beams from the second light source means.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the workpiece is irradiated with coherent light from the light source means, and the workpiece is optically processed by thermal or ablation. It is characterized by:

According to a fourth aspect of the present invention, in the first, second or third aspect, at least one of the oscillation time interval of the first and second light source means and the output energy is variable.

According to a fifth aspect of the present invention, in the first aspect of the present invention, one of the light source means includes:
It is characterized in that harmonics of mode-locked YAG laser light are used.

According to a sixth aspect of the present invention, in any one of the first to fourth aspects, the light source means uses a harmonic of a titanium sapphire laser for generating coherent light. .

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION The optical processing machine of the present invention uses a pulse laser beam. In general, in optical processing using pulsed laser light, parameters relating to the difference in processing characteristics of a workpiece in which metal and plastic are laminated are as follows: (c-1) laser intensity (injection energy per pulse J / cm ² ) (c) -2) Laser wavelength (c-3) One pulse oscillation time width.

In the optical processing, it is natural that the laser intensity of (c-1) affects the processing amount, but the processing state is not always better as the injection amount is larger. In addition, regardless of the thermal processing or the ablation processing, there is a threshold value of the processing energy depending on the thermal conductivity and the binding energy of the processing object for each processing condition.

The laser wavelength of (c-2) has a small dependence when the plasma is cut off in a wide range from infrared light to ultraviolet light, such as a metal. However, for a material such as plastic that is transparent in the visible region and has a very large absorption in the ultraviolet light, the ablation characteristics are more advantageous in the ultraviolet region. Further, as the energy of one photon is larger than the main binding energy to be processed (mainly a single carbon bond in the case of plastic), the processing characteristics are generally better.

The one-pulse oscillation time width of (c-3) is (c-3).
Contrary to 2), the thermal conductivity is poor, such as plastic, and the main heat conduction factor does not significantly affect substances whose molecular vibration is caused. However, the effect is great for a substance such as a metal in which heat conduction is a problem for a few nanoseconds. Generally, the shorter (therefore, the higher the power of light (W)), the better the processing characteristics.

Also, in the f-second pulse region, the light field passes before the plasma excitation by light occurs, so that a deep processing different from the n-second pulse region has a characteristic that can be processed efficiently. become.

Of these three processing parameters, (C)
It is simplest to change the energy intensity of 1), but as described above, it is often redundant both in terms of equipment and efficiency, and the effect is often small.

It is difficult to change the laser wavelength of (c-2). Also, like a YAG laser, from the fundamental wave to the fifth harmonic (wavelengths of 1064 nm, 532 nm, and 355 nm)
m, 266 nm, 213 nm) can be simultaneously oscillated. For example, even if the second harmonic and the fourth harmonic are simultaneously irradiated on the composite material of plastic and metal, the second harmonic only damages the plastic. Poor effect. Also, in order to efficiently guide laser beams of different wavelengths to the same target, all optical components, including lenses and mirrors, must support two wavelengths. Many.

With respect to the one pulse oscillation time width of (c-3), a device with good controllability has been obtained in recent years with the progress of YAG lasers and titanium sapphire lasers.

In general, by outputting a laser beam having a high peak power of about p seconds or less and using the laser beam as a light source means of an optical processing machine, the shape accuracy and the processing amount of the processing object can be improved even with the same total energy amount. It is known that

The total energy per pulse of the P second and f second laser is n
Since it is slightly inferior to pulse lasers of seconds, it is suitable for thin metal processing, but the total energy is often somewhat insufficient for thick plastic processing.

FIG. 5 shows an optical processing machine according to the present invention, wherein a pulse laser (first light source means) having an oscillation time of about p seconds and n
FIG. 4 is a schematic diagram of a main part near a light source unit when a pulse laser (second light source unit) for about a second is oscillated almost simultaneously and processing is performed using a common optical path.

As shown in FIG. 5, a p-second pulse laser 1 and an n-second pulse laser
The second pulse laser 2 is oscillated in synchronization, and is superposed by the photosynthesis means 5 to simultaneously irradiate a predetermined surface.

In this way, in the metal part on the surface, the energy mainly brought by the p-second pulse contributes to the processing, and the metal part is instantaneously removed.

Further, when the processing of the plastic part is started, the effect of the pulse of p seconds is reduced, but the thermal and ablation contributions are almost the same as those of the n seconds part. Processing can be performed.

Therefore, the user can easily drill holes including the metal portions provided on both sides without knowing whether the metal portion is being processed or the plastic portion is being processed. it can.

Next, a specific embodiment of the optical processing machine of the present invention will be described.

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a first light source means, which is a YAG which oscillates coherent pulse light of p seconds (pico seconds).
Made of laser. Reference numeral 2 denotes a second light source means, which is a YAG which oscillates a coherent pulse light of n seconds (+ seconds).
Made of laser. The first and second light source means 1 and 2 constitute one element of the light source means.

A trigger circuit 3 controls the oscillation interval between the two YAG lasers 1 and 2. Reference numeral 4 denotes a half-wave plate for aligning the polarization directions of the laser light from the YAG laser 2. Reference numeral 5 denotes a polarization beam splitting element (polarization beam splitter). Reference numeral 6 denotes a high-speed photodiode for monitoring, which divides a part of the laser beam by a half mirror 6a, detects the amount of the laser beam, and adjusts the phase.

Reference numeral 7 denotes a sampling oscilloscope.
Reference numeral 8 denotes an illumination optical system which irradiates a laser beam having passed through the half mirror 6a onto a mask 9 on which a predetermined pattern is formed.

Reference numeral 9 denotes a mask on which a pattern of a predetermined shape for processing a workpiece such as an orifice plate is formed.

A projection lens 10 projects the mask 9 onto the workpiece 11. The workpiece 11 is made of a plastic plate with a metal protective layer.

In the present embodiment, p from the first light source
The workpiece 11 is optically processed in a pattern of the mask 9 by a combined light beam of at least two coherent lights of the second pulse light and the n second pulse light from the second light source means 2. This maintains good processing characteristics when processing metals, plastics, and the like.

Next, the configuration of the p-second YAG laser of the first light source means 1 will be described.

FIG. 2 shows the p-second YA of the first light source means of FIG.
It is a principal part schematic diagram of a G laser. In FIG. 2, 21 is
Excitation flash lamp, 22 is a YAG crystal of the fundamental oscillation stage, 23 is a rear-stage reflector of the resonator, 24 is a supersaturated dye, 2
5 is an AO modulator, 26 is an etalon plate for band control, 27
Is a front reflector of the resonator, 28 is a photodiode, 29
Is a trigger circuit, 30 is a Pockels optical switch, 3
1 is a flash lamp for excitation, 32 is a YAG crystal of an amplification stage, 33 is a nonlinear crystal for a second harmonic, 34 is a nonlinear crystal for a fourth harmonic, and 35 is a reflecting mirror for a fourth harmonic.

First, when the flash lamp 21 emits light, neodymium in the YAG crystal 22 is excited to emit light,
A field of a fundamental wave (wavelength 1064 nm) grows in the resonator. Of the grown fields, those that exist at the time when an electric field of a certain value or more passes through the supersaturated dye 24 can remain on the resonator, so that the AO modulator 25 controls the transmittance in the resonator whose transmittance is actively controlled. Are made shorter. The bandwidth of each mode is determined by the free dispersion area of the etalon plate 26, and the oscillation time width is determined.

Since this pulse light is weak, amplification is necessary. Therefore, the mode lock pulse oscillation of the basic stage is detected by the photodiode 28, the Pockels optical switch 30 is opened by the trigger circuit 29, and only one pulse light is selected, and then amplified by the amplification stage YAG crystal 32.

The amplified fundamental wave of the YAG laser is doubled by the second-order nonlinear crystal 33, further doubled by the fourth-order nonlinear crystal 34, converted to a wavelength of 266 nm, and reflected by the reflecting mirror 35. Selected and taken out.

Next, the n-second YAG laser of the light source means 2 will be described. FIG. 3 shows n seconds Y of the second light source means 2 of FIG.
FIG. 3 is a schematic view of a main part of an AG laser. In FIG. 3, 41 is
Excitation flash lamp, 42 is a YAG crystal of a fundamental oscillation stage, 43 is a rear reflector of a resonator, 44 is a Pockels optical switch for a Q switch, 45 is a front reflector of a resonator,
46 is an excitation flash lamp, 47 is an amplification stage YAG crystal, 48 is a second harmonic nonlinear crystal, 49 is a fourth harmonic nonlinear crystal, and 50 is a fourth harmonic reflector.

First, when the flash lamp 41 emits light, neodymium in the YAG crystal 42 is excited and a population inversion grows. When the excited state of neodymium has increased to some extent, the Q switch 44 opens, a resonator is formed, and Y
An AG laser fundamental wave is generated. The pulse light passes through the amplification stage YAG crystal 47, which has been excited at the same time. The amplified fundamental wave is converted into a fourth harmonic by the second-order nonlinear crystal 48 and the fourth-order nonlinear crystal 49, and is reflected by the reflecting mirror 50.
Is guided to the outside.

In the present embodiment, oscillation occurs in this manner.
The phase relationship and the intensity ratio of the oscillation time between the two laser pulses of p seconds and n seconds are adjusted so that mainly the metal part can be processed efficiently and with less processing dust (debris). I have.

The intensity ratio of the two laser beams is determined by the flash lamp (2) of both laser devices (light source means) 1 and 2.
1, 31, 41, and 46), the switching timing, and the optical characteristics of the half-wave plate 4 for coupling and the polarizing beam splitting mirror 5 are adjusted.

The phase relationship is adjusted by the following adjustment method.

(D-1) The phase of the trigger signal input to the p-second laser device 1 and the n-second laser device 2 is adjusted.

(D-2) A Q-switch trigger signal for the n-second laser device 2 is generated by a trigger signal for pulse selection of the p-second laser device 1.

(D-3) The number and position of mirrors for guiding the laser light for n seconds are adjusted, and the flight time is managed to adjust the phase.

Normally, (d-2) is often used when synchronization stability of about 1 ns is desired, but (d-1) is used for simple processing.

Such a phase adjustment is performed by observing a signal from the high-speed monitoring photodiode 6 with a sampling oscilloscope 7.

The laser pulse light (hereinafter, referred to as “synthesized laser pulse light”) in which the laser light of p seconds and n seconds generated in this manner is synthesized is similar to the laser light for ordinary optical processing. I'm using The synthesized laser pulse light shaped by the illumination optical system 8 is cut into a processing shape from the pattern of the mask 9, guided to the processing target 11 by the projection lens 10, and processed on its surface.

In the present embodiment, as the processing object 11, any material having a plurality of materials having different processing characteristics, such as gold and a plastic material, can be applied.

The light source means is not limited to two light sources, and three or more light sources may be provided according to the material of the workpiece.

The effects of the first embodiment include the following.

(E-1) Since the two coherent light beams are both fourth harmonics from the YAG laser, they have almost the same wavelength except for the spread of the wavelength due to the shortening of the pulse. Can be done.

(E-2) Since only the same laser such as the YAG laser is used, the replenishment parts, the maintenance method, and the like can be shared, so that the working efficiency is high.

FIG. 4 is a schematic view of a main part of a second embodiment of the present invention.

In FIG. 4, 101 is an f-second titanium sapphire laser, 102 is a non-linear crystal for third harmonic, 103 is a KrF excimer laser for amplification, 104 is a trigger circuit, and 10 is a trigger circuit.
5 is a processing KrF excimer laser, 106 is a combining mirror, 107 is a beam exander, 108 is a mask, 1
Reference numeral 09 denotes an off-axis projection mirror, and reference numeral 110 denotes a plastic on which a surface on which a row of holes is processed is metal-deposited.

The output light from the fs-second titanium sapphire laser 101 oscillated at a wavelength of about 745 nm is converted into a KrF excimer laser having an oscillation wavelength of 24
KrF excimer laser for amplification 10
Inject into 3 and amplify.

On the other hand, the ordinary processing KrF excimer laser 105 is also output by the trigger circuit 104 in synchronization with the laser light from the fs-second titanium sapphire laser 1, and coaxially coherent light (combined laser light) ).

The combined laser light from the combining mirror 106 is
After the beam expander 107 sets the beam diameter to a predetermined size, the mask 108 is illuminated. The laser beam is cut into a predetermined shape by the pattern of the mask 108, and the combined laser beam is projected by a projection mirror 109 onto a workpiece 110 as a processing target.
And a hole is formed in the surface of the workpiece 110.

The effects of this embodiment include the following.

(F-1) Since all optical elements are made of reflecting members, the problem of chromatic aberration is slight.

[0088]

According to the present invention, when an optical workpiece is formed by using a laser beam, a workpiece having a characteristic having a different relationship between energy and a processing characteristic is greatly changed in a processing condition, a total processing energy, and the like. It is possible to achieve an optical processing machine capable of performing stable processing without performing the processing.

In addition, according to the present invention, (g-1) a processing object having extremely different processing threshold values, thermal characteristics, and the like can be simultaneously irradiated with two types of coherent light beams having different time waveforms to simultaneously obtain the same optical characteristics. Can be processed in the system. Therefore, it is possible to stably process a processing target made of different types of composite materials such as metal and plastic.

(G-2) Good thermal conductivity like metal
In the case of laser processing, where the pulse width of the laser processing is short, the coherent light on the short pulse side is increased, and the thermal conductivity is poor, such as plastic, and the pulse width effect is small. If it is desired to perform machining, flexible machining conditions can be set by increasing the ratio on the long pulse side.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a main part of an optical processing machine according to a first embodiment of the present invention.

FIG. 2 is an explanatory view of a p-second YAG laser shown in FIG. 1;

FIG. 3 is an explanatory diagram of the n-second YAG laser in FIG. 1;

FIG. 4 is a schematic diagram of a main part of an optical processing machine according to a second embodiment of the present invention.

FIG. 5 is a conceptual diagram showing superposition control of two lasers according to the present invention.

FIG. 6 is a conceptual diagram showing a processing state by a conventional optical processing method.

FIG. 7 is a schematic view of a main part of a conventional laser processing apparatus.

[Explanation of symbols]

Reference Signs List 1 p-second YAG laser 2 n-second YAG laser 3 trigger circuit for controlling oscillation interval of two YAG lasers 4 1/2 wavelength plate 5 polarized beam splitting element 6 high-speed photodiode for monitoring 7 sampling oscilloscope 8 illumination optical system 9 mask 10 Projection lens 11 Plastic plate with metal protective layer to be processed 21 Flash lamp for excitation 22 YAG crystal of fundamental oscillation stage 23 Post-reflector of resonator 24 Supersaturated dye 25 AO modulator 26 Etalon plate for band control 27 Resonance Pre-reflector of vessel 28 Photodiode 29 Trigger circuit 30 Pockels optical switch 31 Flash lamp for excitation 32 Amplification stage YAG crystal 33 Non-linear crystal for second harmonic 34 Non-linear crystal for fourth harmonic 35 Reflector for fourth harmonic 41 Excitation Flash lamp 42 YAG crystal 43 Post-reflector of resonator 44 Pockels optical switch for Q switch 45 Pre-reflector of resonator 46 Flash lamp for excitation 47 Amplification stage YAG crystal 48 Nonlinear crystal for second harmonic 49 Nonlinear crystal for fourth harmonic 50 4 Reflector for harmonic wave 101 fs titanium sapphire laser 102 Nonlinear crystal for 3rd harmonic wave 103 KrF excimer laser for amplification 104 Trigger circuit 105 KrF excimer laser for processing 106 Combining mirror 107 Beam exander 108 Mask 109 Off-axis projection mirror 110 Plastic on which the surface of the hole array is to be processed metal-deposited 301 Coherent light to be irradiated 302 Gold which is the upper surface protective layer to be processed 303 Plastic occupying the bulk part to be processed 304 Lower surface protective layer to be processed 401 Coherent light source 02 illumination optical system 403 mask 404 projection lens 405 material 406 the image processing apparatus

Claims (6)

[Claims] An optical processing machine for illuminating a pattern on a mask with a light beam from a light source and projecting the pattern on the mask onto a workpiece by a projection lens to optically process the workpiece. An optical processing machine characterized in that the light beam from the light source is a combined light beam obtained by combining light beams from two light source means, ie, first and second light source means, which emit pulse lights having different oscillation times. 2. An optical processing machine for illuminating a pattern on a mask with a light beam from a light source means and projecting the pattern on the mask onto a workpiece by a projection lens to optically process the workpiece. The light flux from the first light source means for emitting coherent light having an oscillation time of 1 ns or less, and the light flux from the second light source means for emitting coherent light having an oscillation time longer than the oscillation time of the first light source means An optical processing machine characterized in that it is a combined light beam obtained by combining 3. The process according to claim 1, wherein the workpiece is irradiated with coherent light from the light source means, and the workpiece is optically processed by thermal or ablation.
Or 2 optical processing machines. 4. An optical processing machine according to claim 1, wherein at least one of an oscillation time interval of said first and second light source means and output energy is variable. 5. An optical processing machine according to claim 1, wherein one of said light source means uses a harmonic of a mode-locked YAG laser beam. 6. An optical processing machine according to claim 1, wherein said light source means uses a harmonic of a titanium sapphire laser to generate coherent light.