JP3257413B2 - Laser processing apparatus and laser processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus and a laser processing method, and more particularly, to a laser drilling apparatus and laser suitable for drilling a circuit board formed by laminating an insulating layer and a conductive layer. It relates to a drilling method.

[0002]

2. Description of the Related Art In general, there is a so-called multilayer circuit board formed by alternately laminating insulating layers and conductive layers on a circuit board. Such a multilayer circuit board has a high mounting density. And is becoming widely used.

More specifically, in a multilayer circuit board, conduction between adjacent conductive layers is obtained by making a hole in an insulating layer and filling the hole with a solder, a conductive paste, or the like.

[0004] As a processing technique for forming a hole in an insulating layer, a technique utilizing laser light has been widely used.

The wavelength of the laser beam used is
For the insulating layer, a wavelength that is easily absorbed and a wavelength that is easily reflected for the conductive layer is used.For example, when the insulating layer is a glass epoxy resin and the conductive layer is a copper foil, a carbon dioxide gas laser beam is used. With the use, only the insulating layer can be selectively removed.

Here, it is needless to say that a hole is formed so that conduction between adjacent conductive layers can be surely obtained.

[0007] As such a first conventional example, there is one described in, for example, JP-A-6-277863.

According to this method, first, mechanical processing is performed on a workpiece to form a hole, and then a laser beam is irradiated to remove the insulating layer and leave only the conductive layer.

When the object is irradiated with the laser beam, the irradiation of the laser beam is adjusted according to the amount of the reflected light. Specifically, the amount of the reflected light detected by the photodetector is detected. Determine that the amount of light received from the conductive layer has been reached, and stop the oscillation of the pulse laser.

On the other hand, Japanese Patent Application Laid-Open No. Sho 61 (1987) discloses a second conventional example in which cutting processing is performed while detecting the intensity of reflected light from a workpiece in a laser processing apparatus as a ratio to the intensity of laser light to be irradiated. -95793.

In FIG. 11 showing such a configuration, a beam splitter 115 provided in an optical path between a laser oscillator 101 and a bend mirror 103 converts a part of a laser beam 102 output from the laser oscillator 101 into a beam. The light is reflected upward as the monitor laser light 118, and its light intensity is detected by the detector 119.

A part of the laser beam 102 reflected from the workpiece 105 is also reflected by the beam splitter 115 downward in the drawing, and the light intensity of the reflected light 116 is detected by a detector 117.

Then, the signal A detected by the detector 119
And the signal B detected by the detector 117, the ratio is calculated by the divider shown in the figure, and the result is inputted to the comparator shown in the figure and compared with the reference value. Then, the NC device 108 controls the movement of the workpiece.

[0014]

However, the above-mentioned prior art has the following problems.

First, in the first conventional example, when the reflected light is detected and the laser beam irradiation is adjusted to perform desired processing, the reflected light is detected as the amount of light received from the conductive layer. This is a configuration in which the oscillation of the pulse laser is stopped. In practice, there is a possibility that the insulating layer may partially remain on the bottom surface of the hole, so that there is a problem that the processed hole shape does not have sufficient conduction. Further, the accuracy of detecting that the laser beam has reached the conductive layer itself is not high.

[0016] Then, in the second conventional example, FIG. 11
In this case, since a part of the output laser beam 102 is extracted by the beam splitter 115 as the monitor laser beam 118, there is a problem that the energy output from the laser oscillator for the purpose of processing is not effectively used. .

In addition, if the workpiece 105 is not perfectly perpendicular to the optical axis of the laser beam 102, the optical path of the reflected laser beam does not match the optical path of the output laser beam, and Light 116 is the detector 117
There is also a problem that the light does not enter.

In addition, a vaporized material or a scattered material remains around the workpiece 105 during or after processing, and when detecting reflected light from the workpiece 105, These vaporized or scattered materials block or scatter reflected light, reducing its intensity, and there is also a problem that the detector 117 cannot perform sufficient detection.

In addition, the beam splitter 11
5 is desirably a low reflectivity for the output laser beam from the viewpoint of effective use of processing energy, and is preferable for the reflected laser beam from the viewpoint of preventing the reflected light from entering the laser oscillator 101 as return light. However, there is also a problem that a conflicting function that a high reflectance is desired is required.

In addition, when the light emitted from the workpiece 105 generated during processing is close to the wavelength of the laser beam 102, the intensity of the emitted light is added to the intensity of the reflected light when the detector 117 detects the reflected light 116. Is detected and
There is also a problem that the detection sensitivity of the reflected light 116 is reduced.

The present invention has been made in view of the above points, and particularly, accurately detects a state of drilling of an object to be processed, and controls a laser oscillator thereafter to perform ideal drilling.
As a result, an object of the present invention is to provide a laser processing apparatus and a laser processing method capable of performing a hole processing such that conduction between adjacent conductive layers can be reliably obtained.

[0022]

In order to solve the above-mentioned problems, the present invention provides a method for processing an object having a region to be machined and a region not to be machined sequentially in a machining direction by a laser beam. A laser processing apparatus and a laser processing method having a main configuration for controlling a laser oscillator such that a laser beam is emitted so as to further impart a predetermined processing light intensity after it is detected that the laser beam has reached a non-processing scheduled area. .

With such a configuration, an ideal hole processing is performed by precisely detecting the state of the hole processing of the object to be processed, and controlling the laser oscillator thereafter, and as a result, conduction between the adjacent conductive layers is achieved. To provide a laser processing apparatus and a laser processing method capable of performing a hole processing such that a hole can be reliably obtained.

[0024]

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, there is provided a processing apparatus according to the first aspect, wherein light reflectances in the processing direction are different from each other.
Processing object having a laminated structure including a constant layer and a non-processing layer
A laser processing apparatus for processing an object, a laser oscillator for emitting a laser beam pulse, a control device for controlling said laser oscillator, an optical system for propagating a previous SL laser beam to the workpiece, the processing object a detector for detecting the light intensity of the reflected light from the object, and an optical system for propagating the reflected light to the detector, before Symbol controller working area, has reached the non-planned processing layer Is detected by using the reflected light, and then at least one pulse of laser light
The laser light to give a predetermined processing light intensity of
As an additional irradiation, a laser processing apparatus that controls the laser oscillator, and a processing step of processing the processing target object by a pulsed laser beam, as described in claim 15, and from the processing target object. A detecting step of detecting the light intensity of the reflected light, and detecting that the processing region has reached the non-processing scheduled portion of the processing object from the light intensity of the reflected light in the detecting step, and further to the processing object. At least one pulse
And a step of applying a predetermined processing light intensity composed of laser light.

Thus, the state of the hole drilling of the object to be processed is accurately detected, and the subsequent laser oscillator is controlled to expose the non-machining scheduled layer and the non-machining scheduled portion, which is the non-machining region, as a complete hole bottom. The ideal drilling is performed.

[0026] Here, specifically, as in claim 2, the machining schedule layers, the reflectance is relatively low low reflectance layer, the non-planned processing layer, the reflectance relative A high-refractive-index layer for processing an object to be processed.
The processing equipment .

Further, as described in the third aspect, the manner in which the intensity of the reflected light is increased changes, so that the processing area is not added.
A configuration that detects that the vehicle has reached the scheduled work layer is preferable,
Further, it is more preferable to detect the change in the increase in the intensity of the reflected light by using the time differential coefficient of the intensity of the reflected light.

Thus, the state of the hole drilling of the workpiece can be more accurately detected. On the other hand, as set forth in claim 5, the control device of the laser processing apparatus is configured such that the processing area is not scheduled to be processed.
After it has reached a constant layer is detected, a configuration for controlling the laser oscillator to emit laser light to impart the processing light intensity obtained in advance, as claimed in claim 16, wherein the laser processing It is preferable that the method further includes a processing light intensity calculating step of obtaining a predetermined processing light intensity in advance.

Thus, ideal drilling in which the non-processed layer and the non-processed portion, which are the non-processed areas, are exposed as complete hole bottoms is performed more reliably.

[0030] or, as claimed in claim 6, wherein the control unit of the laser processing device, after the machining area has reached the non-processing scheduled layer is detected, and the total light intensity of the laser light may be used for processing A configuration in which a laser oscillator is controlled so as to emit a laser beam so as to provide a processing light intensity corresponding to a difference between a light intensity of the reflected light and a light intensity of the reflected light when the arrival at the non-processing scheduled layer is detected. As described in 17, the laser processing method further includes a difference between the total light intensity of the laser light that can be used for the processing and the light intensity of the reflected light when it is detected that the processing region has reached the portion to be processed. May be provided with a processing light intensity calculation step of obtaining a predetermined processing light intensity.

In this way, ideal drilling in which the non-processed layer and the non-processed portion, which are non-processed areas, are exposed as complete hole bottoms can be performed more reliably.

[0032]

[0033]

Furthermore, as according to claim 7, comprising a rear detector for detecting the light intensity of the laser light emitted from the back side of the laser oscillator, detecting the light intensity of the reflected light from the workpiece The signal detected by the detector may be a laser processing apparatus configured to be normalized by the signal detected by the rear detector.

As a result, the fluctuation of the laser beam intensity and the like are canceled, and the state of the hole drilling of the workpiece can be more accurately detected.

Furthermore, as according to claim 8, in front of the detector for detecting the light intensity of the reflected light from the workpiece, the cylindrical having a pair of ends capable of passing the reflected light reflector The reflector has an opening area at a front end of the pair of end portions larger than an opening area at a rear end of the pair of end portions, and the inner surface thereof has reflected light. it is preferable that is made of a material capable of reflecting, further as claimed in claim 9, wherein the inner surface of the reflector of the cylindrical, it is preferably made of a polygonal and / or curved.

As a result, the reflected light is reliably detected, and the state of the hole drilling of the object to be processed can be more accurately detected.

[0038] Moreover, as claimed in claim 10, wherein, while the reflected light from at least workpiece is detected, the laser processing apparatus having a gas flow application means for applying a gas flow in the vicinity of the workpiece But often, as claimed in claim 11, further it may be a laser processing apparatus having a gas flow suction means for sucking the gas flow passing through the vicinity of the object is applied by the gas flow application means.

Thus, the reflected light is not affected by scattering or the like, and the state of the hole drilling of the object to be processed can be detected more accurately.

[0040] Furthermore, as according to claim 12, an optical system for propagating the laser beam to the workpiece, and an optical system for propagating the reflected light from the workpiece to the detector, a common polarization beam splitter And a common quarter-wave plate disposed between the polarizing beam splitter and the object to be processed . Further, as described in claim 13 ,
The laser beam incident on the polarizing beam splitter is a first laser beam.
It is polarized light having a polarization direction and transmitted through the polarizing beam splitter, and after being converted into circularly polarized light by the ４ wavelength plate, is reflected by the object to be processed to become the reflected light,
The reflected light is converted into laser light having a second polarization direction different from the first polarization direction by the quarter-wave plate, and the intensity of the reflected light is detected by the polarization beam splitter. The laser processing apparatus may be configured to be reflected in the direction. In this case, as in claim 14, the apparatus further includes a wavelength filter in the optical path of the reflected light that transmits only a wavelength near the reflected light. It may be a configuration.

Thus, the laser light is effectively used,
It is possible to more accurately detect the state of the hole drilling of the processing object.

Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic view of a laser processing apparatus according to the present embodiment. In FIG. 1, 1 is a pulse laser oscillator used as an example of a processing light source, 2 is a first scanning mirror, 3 is a second scanning mirror, 4 is a processing condenser lens,
Reference numeral 5 denotes a beam splitter, which forms an optical system in an optical path, and is arranged in the order of the beam splitter 5, the scanning mirrors 2, 3, and the condenser lens 4 from the laser oscillator 1 side.

Here, as the pulse laser oscillator 1 used in the present embodiment, for example, a carbon dioxide laser oscillator excited by microwaves can be suitably used.

Next, reference numeral 6 denotes a photodetector for detecting a reflected laser beam from an object to be described later, and 7 denotes scanning mirrors 3 and 4.
, A moving mechanism 8 for moving the object to be processed, and 9 an arithmetic processing unit for performing an arithmetic operation using an output from the photodetector 6.

Here, reference numeral 10 denotes a multilayer substrate to be processed. The multilayer substrate includes a first conductive layer 11, an insulating layer 12, and a second conductive layer 13, and the insulating layer 12 is an object to be processed. The conductive layers 11 and 13 are not originally intended to be processed, but are typically made of a metal material. However, the object to be processed is not limited to such a configuration, and can be applied to any object having a structure in which the reflectance with respect to the laser light is different in the direction of processing by the laser light. It is.

Reference numeral 14 denotes a pulsed output laser beam oscillated from the laser oscillator 1, and reference numeral 15 denotes a reflected laser beam reflected from the multilayer substrate 10, which is an object to be processed, in the direction of the multilayer substrate 10. The output laser light 14 in the optical path toward the optical path and the reflected laser light 15 in the optical path reflected by the multilayer substrate 10 and returning in the direction of the laser oscillator 1 are combined with the beam splitter 5 via the scanning mirrors 2 and 3 and the condenser lens 4 to form a multilayer. The direction indicated by the laser light 16 is opposite to that of the substrate 10, but the light path is the same.

With the above configuration, a processing hole 17 is formed in the multilayer substrate 10. This operation will be described in more detail.

First, the output laser light 14 emitted from the pulse laser oscillator 1 passes through the beam splitter 5 and the first scanning mirror 2 constituted by a galvanometer mirror and the second scanning mirror 2 constituted by a galvanomirror. The light is sequentially reflected by the scanning mirror 3 so as to be scannable in accordance with a required processing mode.

Here, in the case of the present embodiment, the first scanning mirror 2 and the second scanning mirror 3 are configured to scan the output laser light 14 in directions orthogonal to each other.
As a result, the output laser beam 14 is configured to be able to scan the multilayer substrate 10 two-dimensionally.

Then, the light is incident on the processing condensing lens 4 composed of an fθ lens, and while being condensed, the light is incident on the multilayer substrate 10 installed on the processing object moving mechanism 8 at the processing position.

As described above, processing is performed to form a processing hole 17 in the multilayer substrate 10 using the converged output laser light.

Then, a part of the output laser light 14 applied to the multilayer substrate 10 is reflected by the multilayer substrate 10 to become a reflected laser light 15.

The reflected laser light 15 is the output laser light 1
The laser beam 4 propagates in the opposite direction along the laser beam path, and reaches the beam splitter 5 in the order of the condenser lens 4 and the scanning mirrors 3 and 2 , is reflected by the beam splitter 5, and enters the reflected light detector 6. Will be done.

The detection signal relating to the light intensity of the reflected laser beam 15 detected by the reflected light detector 6 is sent to the arithmetic processing unit 9 for arithmetic processing, and the output signal of the arithmetic processing unit 9 is On the other hand, it is fed back to the laser oscillator 1. On the other hand, it is also sent to the scanning mirror control device 7, and the scanning mirror control device 7
Control.

Now, the light intensity of the reflected laser light 15 detected by the reflected light detector 6 will be discussed in more detail.

FIG. 2A is a diagram schematically showing a case where the output laser light 14 applied to the processing hole 17 is reflected and absorbed.

In FIG. 2A, a is a component absorbed by the insulating layer 12, b is a component absorbed by the second conductive layer 13, and c is a component that is transmitted through the insulating layer 12 and passes through the second conductive layer 13. Components that actually pass through the insulating layer 12 remaining after reflection in accordance with the progress of processing,
Includes one or both of which do not pass because they have disappeared. ) Are shown.

Here, the component a absorbed by the insulating layer 12
Contains components consumed by processing and components absorbed as heat.

A part of the output laser light 14 is reflected on the surface of the first conductive layer 11 and / or the insulating layer 12, and the intensity of the reflected light is constant. It has been omitted here.

Also, for the sake of simplicity of description, the processing hole 1
7, the intensity of the output laser light 14 is assumed to be DC irradiation that is constant over time, and the spatial intensity distribution is also
It was assumed to be uniform.

Even when the output laser beam 14 is pulse-irradiated, if the information for each pulse is stored in the arithmetic processing unit 9 and an operation for substantially ignoring the pulse pause time is performed, the DC-irradiation can be performed. Needless to say, processing similar to that described above is possible.

Next, FIG. 2B is a diagram schematically showing the consumption rate of the intensity of the output laser beam 14 applied to the processing hole 17, in which the horizontal axis represents time and the vertical axis represents the irradiation. This is the output laser light intensity with the total intensity being 1.

First, the component a shown in FIG. 2A gradually decreases as the processing proceeds and the thickness of the insulating layer 12 becomes thinner, and its intensity becomes 0 when the processing is completed. .

The component b and the component c shown in FIG. 2A increase exponentially as the processing proceeds and the thickness of the insulating layer 12 becomes thinner. Is a constant value.

Next, with respect to the temporal change of each component before and after the processing is completed, the component a becomes 0 after the processing is completed, that is, because the insulating layer 12 has disappeared.

Attention is paid to the component c. At the moment when the processing is completed, the reflected laser beam 15 which has increased exponentially until now shows a discontinuous intensity change because it keeps a constant value thereafter. Become.

This means that such reflected laser light 1
By detecting the discontinuous change in strength of No. 5, the machined hole 17 is formed, and it can be understood that the hole machining is completed.

That is, in this case, the reflected laser beam 15
Indicates that the processed region has reached the region with different reflectivity, that is, from the insulating layer 12 to the conductive layer 13.

The above description has been made on the assumption that the spatial intensity distribution of the output laser beam 14 is uniform.

In practice, there is generally a case where there is a small difference in strength between the strength distributions, and furthermore, a place where the insulating layer 12 is easily processed and a place where the insulating layer 12 is hardly processed are mixed. Hole processing, the entire bottom surface of the hole
Instead of reaching the conductive layer 13, first, the tip end of the processing hole reaches the second conductive layer 13, and thereafter, the second conductive layer 1
3 has undergone a processing process in which the area of the exposed portion gradually increases.

FIG. 3A is a diagram schematically showing the consumption rate of the intensity of the output laser beam 14 applied to the processing hole 17 in such a case.

In FIG. 3A, the time when the tip of the processing hole reaches the second conductive layer 13 is t1, the time when the processing is completed is t2, and the other elements in the drawing are the same. It is based on FIG.

First, as the processing proceeds and the thickness of the insulating layer 12 becomes thinner, the component a gradually decreases, and its strength becomes 0 at the time when the processing is completed.

The components b and c increase exponentially until the time t1 is reached.
Until the machining, the degree of increase is loosened while gradually decreasing the inclination, and the intensity becomes a constant value at the time when the machining is completed.

Here, focusing on the component c, the state of increase in light intensity changes at time t1 when the tip of the machined hole reaches the second conductive layer 13 as a boundary.

From the start of processing to time t1, the component c increases exponentially, the slope of the curve showing the light intensity continues to increase, and from time t1 to time t2, the degree of increase of the component c gradually increases. When the time t2 is reached, the slope of the curve becomes 0, and the machining ends.

That is, by detecting the state of the increase in the intensity of the reflected light, that is, the change in the inclination, it is possible to detect that the tip of the processed hole has reached the second conductive layer 13. .

That is, in the case shown here, the slope of the curve indicating the light intensity continues to increase before the time t1, and the slope of the curve continues to decrease after the time t1, with the time t1 as a boundary. Therefore, the curve showing the light intensity is t
1 is defined as an inflection point. Before t1, for example, the secondary derivative always has a positive value, and after t1, for example, the secondary derivative always has a negative value. And
It is possible to detect that the tip of the processing hole has reached the second conductive layer 13. However, the detection can be performed in the same manner by using a primary differential coefficient instead of the secondary differential coefficient.

As described above, by examining the sign of the second-order time differential coefficient of the light intensity of the reflected laser light 15, it is possible to detect that the state of increase in the light intensity has changed.

The change in the manner in which the light intensity increased was that the processed region had a different reflectivity, that is, the insulating layer 1
This indicates that the conductive layer 13 has reached the conductive layer 2.

Now, it is detected that the intensity of the reflected laser beam 15 has increased, and even if it appears that the drilling has been completed, actually, the insulating layer 12 slightly remains for some reason. May have.

For example, the output laser beam 14 used in actual processing usually has an intensity distribution such as a Gaussian distribution. In this case, the frequency at which the insulating layer 12 remains is determined by the uniform intensity distribution. More than when output laser light having

The processed hole 1 in which the insulating layer 12 remains as described above
As shown in FIG. 3B, which is a typical view of FIG. 7, the insulating layer 12 remains at the boundary between the bottom of the hole and the wall of the hole. If the processing is terminated in such a state, In the processing hole 17,
Even if the solder or the conductive paste is embedded, sufficient conductivity cannot be obtained, resulting in poor conduction.

As described above, by simply detecting that the intensity of the reflected laser beam 15 has increased, the required processing hole 17 is completely formed, and it is accurately determined that the hole processing is completed. Can not be determined.

Therefore, in the present embodiment, after detecting that the state of increase in the intensity of the reflected laser beam 15 has changed, the necessary processing light intensity is further added to the processing hole 17 to be processed. It was adopted.

After detecting such a change in the increase in light intensity, the processing light intensity to be added is statistically determined in advance from the required number of samples when the material of the processing target is determined. Alternatively, it may be obtained each time from the difference between the total intensity of the output light used for drilling the hole and the intensity of the reflected light immediately after detecting the change point of the increase in the light intensity.

In the case of a general multi-layer substrate used in the present embodiment, in the state as shown in FIG. 3B where the insulating layer 12 slightly remains, the hole processing is completed. Although it is unsatisfactory to perform, since the amount of the remaining insulating layer 12 is very small, it is usual that reliable irradiation can be realized by performing additional irradiation with at least one pulsed laser beam. In some cases, the processing light intensity may be added in such a rough manner.

Therefore, when the processing light intensity is added by additional irradiation of at least one pulsed laser beam,
The operation will be described in more detail.

First, consider a case in which a series of hole drilling, that is, a process of continuously irradiating a pulse laser beam to one hole drilling until the hole drilling is completed.

The reflected laser light 1 detected by the reflected light detector 6
In the case where the intensity of the reference numeral 5 changes continuously, the arithmetic processing unit 9 outputs a command to the pulse laser oscillator 1 to irradiate the next pulse laser beam.

In this case, the scanning mirror controller 7 is further provided with the first scanning mirror 2 and the second scanning mirror 3.
Outputs a command not to drive and continues machining.

If it is detected that the state of increase in the intensity of the reflected laser beam 15 has changed, the arithmetic processing unit 9
Outputs an instruction to the pulse laser oscillator 1 to additionally irradiate at least one pulse laser beam.

In this case, a command not to drive the first scanning mirror 2 and the second scanning mirror 3 is output to the scanning mirror control device 7 while the pulse laser oscillator 1 is additionally irradiating. Continue processing.

Then, after the additional irradiation of at least one pulse is completed, the currently targeted hole machining is completed.

Next, the arithmetic processing unit 9 drives the scanning mirror control unit 7 to drive one or both of the first scanning mirror 2 and the second scanning mirror 3 to carry out the next hole machining. And a necessary number of holes are sequentially formed.

Next, parallel hole processing, that is, one pulse laser beam is irradiated to one hole, and the next pulse laser beam on the time axis is irradiated to another hole. Think about what you're doing.

The reflected laser light 1 detected by the reflected light detector 6
If the intensity of the reference numeral 5 changes continuously, the arithmetic processing unit 9 does not output a special command and the processing is continued as it is.

If it is detected that the state of increase in the intensity of the reflected laser beam 15 has changed, the arithmetic processing unit 9
Stores the position of the hole and stores the pulse laser oscillator 1
, An instruction to additionally irradiate at least one pulsed laser beam is output.

In this case, a command not to drive the first scanning mirror 2 and the second scanning mirror 3 is output to the scanning mirror control device 7 while the pulse laser oscillator 1 is additionally irradiating. , Continue processing, after this processing is completed,
The arithmetic processing device 9 prevents the scanning mirror control device 7 from being further irradiated with the pulsed laser light, that is, the aiming of the first scanning mirror 2 and the second scanning mirror 3 is performed. A command is sent so as not to point to this hole, and the processing for this hole ends.

Then, the arithmetic processing unit 9 performs parallel hole machining until machining of all holes is completed.

As described above, according to this embodiment, the state of the hole drilling of the object to be processed is accurately detected by utilizing the change in the state of the increase in the reflected light intensity, and the processing light intensity is added. By doing so, it is possible to reliably perform the hole processing so that conduction between the adjacent conductive layers can be reliably obtained.

Further, unnecessary oscillation of the output laser light can be avoided, and the processing throughput can be increased.

In this embodiment, the laser oscillator is a pulse laser oscillator. However, there is a case where a laser oscillator that continuously emits a laser beam can be used in relation to an object to be processed.

In this embodiment, a galvano mirror is used as a scanning mirror. However, a similar effect can be obtained by using a polygon mirror, an acousto-optic device, an electro-optic device, a hologram scanner, or the like.

In this embodiment, the fθ lens is used as the processing condensing lens 4. However, a similar effect can be obtained by using an optical system in which a plurality of single lenses or Fresnel lenses are combined. is there.

Further, in the present embodiment, the beam splitter 5 comprises the pulse laser oscillator 1 and the first scanning mirror 2
However, the position is not limited to this position as long as a similar function can be obtained.

(Embodiment 2) Hereinafter, Embodiment 2 of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a schematic view of a laser processing apparatus according to the present embodiment. The configuration of the present embodiment is different from the configuration of the first embodiment in that a rear light detector 18 is provided behind the pulse laser oscillator 1 and the rear laser light 19 emitted from the rear side of the pulse laser oscillator 1 is Rear light detector 18
Embodiment 1 except that the configuration for detecting by
Is the same as

That is, in this embodiment, the basic function of detecting the reflected laser light and controlling the processing is the same as that of the first embodiment. It has a configuration that enhances the function of detection.

In the first embodiment, the processing is controlled by detecting that the state of increase in the intensity of the reflected laser beam 15 has changed.

However, in the first embodiment, the output laser light 1
4 is effective when the intensity of the reflected laser light 15 has a temporally invariant intensity, and when the absolute intensity of the reflected laser light 15 is weak, for example, the time profile of the pulsed laser light intensity has a trigonometric function or a quadratic function. However, it is very difficult to ensure the detection accuracy, for example, when the intensity changes at the rising or falling of the pulse.

In order to solve this problem, if the intensity of the reflected laser light 15 is normalized by the intensity of the laser output light 14 by arithmetic processing, sufficient detection can be performed even when the absolute intensity of the reflected laser light 15 is weak. Becomes possible.

Since the laser output light 14 is oscillated for processing, it is not preferable to use the laser output light 14 for other purposes such as monitoring the output light.

Therefore, in the present embodiment, instead of detecting the laser output light 14, a configuration is provided in which the rear laser light 19 emitted from the rear side of the pulse laser oscillator 1 is detected.

Since the intensity of the rear laser light 19 is proportional to the intensity of the laser output light 14, if the purpose is to detect the intensity distribution, the same effect can be obtained by using either of them. is there.

Further, since the rear laser beam 19 does not contribute to the processing, that is, energy that has been wasted, so to speak, it is very economical to use this laser beam.

In the operation of the present embodiment, the rear laser light 19 is detected by the rear light detector 18, and the detected signal is sent to the arithmetic processing device 9, and the reflected light is reflected by the arithmetic processing device 9. The arithmetic processing is performed so as to normalize the signal together with the signal from the detector 6. The control of the subsequent processing based on the arithmetic result is the same as that described in the first embodiment.

As described above, in the present embodiment, by normalizing the laser beam intensity using the rear laser beam, the state of the hole machining of the object to be machined is accurately detected and machining is controlled. Not only can a hole be formed so that conduction between adjacent conductive layers can be reliably obtained, but also unnecessary oscillation of output laser light can be avoided, and the processing throughput can be increased.

(Embodiment 3) Hereinafter, Embodiment 3 of the present invention will be described in detail with reference to the drawings.

FIG. 5 shows that, when laser light is incident on multilayer substrate 10 in the first embodiment, the perpendicular to the surface of multilayer substrate 10 and the optical path of the laser light are not parallel, and the optical path of the reflected laser light is output. FIG. 4 is a schematic diagram showing reflected laser light around the beam splitter 5 and the reflected light detector 6 when the laser light deviates from the optical path of the laser light.

In FIG. 5, reference numeral 20 denotes a detecting section of the reflected light detector 6, in which the original reflected laser light 15 when the same optical path as that of the output laser light is folded is represented by a dotted line, and The solid line represents the reflected laser light 21 that is folded back on an optical path different from the laser light.

Of course, when the laser light is incident on and reflected from the multilayer substrate 10, the multilayer substrate 10 is arranged between the processing condenser lens 4 and the multilayer substrate 10 such that the optical paths of the input and output laser beams are completely matched. Although it is desirable to be installed on the processing object moving mechanism 8, the reflected laser light is reflected by the reflected laser light 21 as shown in FIG. The optical path may deviate from the original optical path.

As described above, when the installation angle of the multilayer substrate 10 is θ
In the case of a change, the angle deviation of the reflected light is 2θ, and at this time, the distance D of the deviation of the reflected laser light at the detection unit 20 is L = the path length from the multilayer substrate 10 to the detection unit 20.
Is given by the following (Equation 1).

[0125]

(Equation 1)

That is, as shown in (Equation 1), the path length L
The longer the distance becomes, the larger the displacement distance D becomes, and the distance D deviates from the detection unit 20 of the reflected light detector 6 which should be incident.

Therefore, in the present embodiment, as shown in FIG. 6, a configuration in which a cylindrical reflector 22 is provided for the detection unit 20 is employed.

According to this configuration, the reflected laser beam 21 that cannot be directly incident on the detecting section 20 can be repeatedly reflected by the cylindrical reflector 22 and finally incident on the detecting section 20. Become.

The diameter of the cylindrical reflector 22 on the incident side is set to be larger than the diameter on the side of the detecting section 20. The specific ratio is determined by the relative distance between the designed optical system and the multilayer substrate. It is determined in consideration of the estimation of the position error and the like.

As described above, in this embodiment, by providing the cylindrical reflector, the optical path of the reflected laser beam from the object to be processed is shifted so that the reflected laser beam is incident on a portion other than the detection section of the reflected light photodetector. Even in this case, the reflected laser beam can be introduced into the detection unit, and the reflected laser beam intensity indicating the state of the hole drilling of the processing target can be more accurately detected.

The material of the cylindrical reflector 22 is a material having a high reflectance with respect to the wavelength of the reflected laser light, for example,
In the case of a processing apparatus using a carbon dioxide laser, it is preferable to use copper, aluminum, gold, or the like.

Further, a material having a low reflectance can be suitably used if it is used as a periodic structure such as a multilayer film. Further, the shape of the inner surface of the cylindrical reflector 22 may be plural if the entrance area of the reflected laser beam 21, that is, the opening area on the beam splitter 5 side is larger than the exit side, that is, the opening area on the detection unit 20 side. May be formed by laminating polygons, or may be formed by curved surfaces, or may be formed by mixing such polygons and curved surfaces.

Embodiment 4 Hereinafter, Embodiment 4 of the present invention will be described in detail with reference to the drawings.

FIG. 7 is a schematic diagram showing the state of the vicinity of the multilayer substrate 10 during or after laser drilling according to the present embodiment.

When processing is performed with the configuration described in the first embodiment, the material 23 vaporized by the processing and the scattered material 24 may remain above and near the processing hole 17.

The vaporized material 23 and the scattered material 24 shield or refract the reflected laser beam 15 and reduce the intensity thereof. As a result, the reflected light intensity cannot be sufficiently detected. Would.

Therefore, in the present embodiment, a gas flow 25 is applied to the processing region of the multilayer substrate 10 in order to remove the vaporized material 23 and the scattered material 24 from the optical path of the reflected laser light 15. The configuration is further provided in the first embodiment.

The gas flow 25 applied in this manner removes the vaporized material 23 and the scattered material 24 existing on the optical path of the reflected laser light 15 in the vicinity of the processing hole 17. As a result, the reflected laser light 15 The laser beam travels on the laser beam path while maintaining the light intensity without being shielded or refracted at all, and the hole 17 can be reliably processed.

As described above, in the present embodiment, by providing a means for removing the vaporized material generated during processing, the light intensity of the laser light is not reduced, and This makes it possible to accurately detect the intensity of the reflected laser beam, which indicates the state of hole machining of the object.

In order to eliminate the vaporized material generated during the processing, not only the gas flow 25 is blown in the vicinity of the multilayer substrate, but also a structure in which the gas is sucked in the vicinity of the multilayer substrate is used. Needless to say, a similar effect can be obtained by combining these.

Embodiment 5 Hereinafter, Embodiment 5 of the present invention will be described in detail with reference to the drawings.

FIG. 8 is a schematic diagram of a reflection optical system constituted by the polarization beam splitter 26 and the quarter-wave plate 27 according to the present embodiment. These are replaced with the beam splitter 5 in FIG. Things. The other configuration has the same configuration as that of the first embodiment.

Here, the polarization beam splitter 26
Has a very high transmission for s-polarized light and p
It has a very low transmittance for polarized light.

When the incident light is circularly polarized, the outgoing light is linearly polarized, and when the incident light is linearly polarized, the outgoing light is circularly polarized. Is to be converted.

In the above configuration, the s-polarized laser light 28 traveling from the right in FIG. 8 is incident on the polarization beam splitter 26 and transmitted as it is.

Here, when the output laser light is circularly polarized, it is necessary to install a quarter-wave plate between the laser oscillator and the polarization beam splitter 26 so that the light becomes s-polarized light.

Next, the s-polarized laser light 28 enters the quarter-wave plate 27. At this time, a phase difference is given to the polarized light component, and the laser light transmitted through the quarter-wave plate is circularly polarized. It becomes a laser beam 29.

Then, processing is performed using this laser light, and a part thereof becomes reflected light, and is again incident on the quarter-wave plate 27 as circularly polarized laser light 30 from the right in FIG.

Then, by passing through the quarter-wave plate, the circularly-polarized laser light 30 becomes a p-polarized laser light 31 and enters the polarization beam splitter 26.

Then, the polarization beam splitter 26
Since it has a very low transmittance for polarized light, most of the p-polarized laser light 29 is reflected and enters the reflected light detector 6.

Next, the technical significance of using the polarizing beam splitter 26 and the quarter-wave plate 27 will be specifically described.

FIG. 9A is a schematic diagram showing the intensity state of the laser beam around the beam splitter 5 in FIG. 1, and FIG. 9B is a diagram showing the relationship between the polarization beam splitter 26 and the polarization beam splitter 26 in this embodiment. FIG. 9 is a schematic diagram showing an intensity state of a laser beam when a four-wavelength plate 27 is used.

Here, assuming that the reflectance of the beam splitter 5 is r, the transmittance is t, the intensity of the output laser beam 14 is I, and the reflectance on the multilayer substrate as the object to be processed is R, FIG.
As shown in (a), the intensity of the reflected laser light 15 incident on the reflected light detector 6 is (t × r × R × I).

On the other hand, the transmittance of the polarizing beam splitter 26 for s-polarized light is t ′, the reflectance for p-polarized light is r ′,
Assuming that the intensity of the s-polarized laser light 28 is I and the reflectivity on the multilayer substrate as the object to be processed is R, the p-polarized laser light 31 incident on the reflection detector 6 as shown in FIG. The intensity is represented by (t ′ × r ′ × R × I).

That is, the ratio α of the intensity of the p-polarized laser beam 31 to the intensity of the reflected laser beam 15 of the present embodiment to the intensity of the reflected laser beam 15 of the first embodiment using the beam splitter 5 is as follows. (Equation 2).

[0156]

(Equation 2)

Here, as an example, the beam splitter 5
Are 10% and 90%, respectively, and the reflectance r ′ for the p-polarized light of the polarizing beam splitter 26 and the transmittance t ′ for the s-polarized light are 50%, respectively.
When the intensity ratio α in the case where it can be set to 99% is obtained,
The following (Equation 3) is obtained.

[0158]

(Equation 3)

As described above, it is confirmed that the intensity of the reflected laser beam can be increased by using the polarization beam splitter 26 and the quarter-wave plate 27 in combination with a high degree of freedom in setting the reflectance and the transmittance. Was.

As described above, in the present embodiment, the polarization beam splitter having a high degree of freedom in setting the reflectance and the transmittance can be used.
By using a combination with a 波長 wavelength plate, the intensity of the laser beam incident on the reflected light detector can be increased, and not only can the laser beam intensity be detected accurately, but also the energy of the output laser beam can be efficiently reduced. It can be used for processing.

Embodiment 6 Hereinafter, Embodiment 6 of the present invention will be described in detail with reference to the drawings.

FIG. 10 shows a wavelength filter 3 according to this embodiment.
FIG. 2 is a schematic diagram showing a state around a beam splitter 5 and a reflected light detector 6 when the light-emitting device 2 is used.

Here, the wavelength filter 32 is a filter having a function of transmitting only near the wavelength of the output laser light 14, and cannot transmit other wavelengths therethrough.

In FIG. 10, the multi-layer substrate often exhibits a light emitting phenomenon due to processing to some extent, but this light emitting phenomenon includes various kinds of light such as ultraviolet light, visible light, and infrared light. Generally, light of a wavelength is included.

The light thus emitted is transmitted from the multilayer substrate 10 to the laser light path 16 together with the reflected laser light 15.
Going up, part of it is reflected by the beam splitter 5,
The light enters the reflected light detector 6.

However, it is natural that the reflected light detector 6 wants to detect only the reflected laser beam 15, and the light emission generated during processing is an unnecessary component that becomes noise at the time of detection.

Therefore, in the present embodiment, the wavelength filter 32 provided immediately before the reflected light detector 6 blocks light having a wavelength other than the wavelength of the reflected laser light 15.

Therefore, light serving as an unnecessary noise component is eliminated by the wavelength filter 32, and only the reflected laser light 15 enters the reflected light detector 6.

As described above, in the present embodiment, by providing the wavelength filter for eliminating the extra light serving as the noise component, the reflected laser beam intensity indicating the state of the hole drilling of the processing object can be detected more accurately. It is possible to do.

The wavelength filter 32 is desirably placed immediately before the reflected light detector 6 for the purpose. However, the wavelength filter 32 may be placed in the laser beam path 16 if its function is sufficient.

In each of the above embodiments, it goes without saying that the respective components can be appropriately combined with each other as long as the functions are not impaired.

[0172]

According to the above arrangement, the state of the hole drilling of the object to be processed is accurately detected by utilizing the change in the state of the increase in the reflected light intensity, and the processing light intensity is added. ,
Drilling can be performed reliably so that conduction between adjacent conductive layers can be reliably obtained.

Further, useless oscillation of the output laser light can be avoided, and the processing throughput can be increased.

Further, by normalizing the laser beam intensity using the rear laser beam, it is possible to accurately detect the state of the hole drilling of the object to be processed, and to control the drilling to perform the hole drilling with higher precision. In addition to this, it is possible to avoid unnecessary oscillation of the output laser light, and the processing throughput is increased.

Further, by providing the cylindrical reflector, even if the optical path of the reflected laser beam from the object to be processed is shifted and the reflected laser beam is incident on a portion other than the detecting portion of the reflected light photodetector, the reflected laser beam is applied to the detecting portion. Can be introduced, and the reflected laser beam intensity indicating the state of the hole drilling of the processing target can be more accurately detected.

Further, by providing a means for removing vaporized material generated during processing, the intensity of the laser beam is not reduced, and the reflection indicating the state of hole processing of the object to be processed is performed. The laser beam intensity can be detected more accurately.

Further, the configuration using a combination of a polarizing beam splitter having a high degree of freedom in setting the reflectance and transmittance and a quarter-wave plate allows not only accurate detection of the laser beam intensity but also the output laser beam. Energy can be efficiently used for processing.

Further, by providing a wavelength filter for eliminating extra light serving as a noise component, it is possible to more accurately detect the intensity of the reflected laser beam that indicates the state of drilling a hole in a workpiece.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a laser processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an ideal output laser beam intensity in the laser processing apparatus.

FIG. 3 is a diagram illustrating the actual output laser beam intensity in the laser processing apparatus.

FIG. 4 is a schematic diagram of a laser processing apparatus according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating an optical path of a laser beam of a laser processing apparatus according to a third embodiment of the present invention.

FIG. 6 is a schematic diagram in which the cylindrical reflector is installed.

FIG. 7 is a schematic diagram showing a state near a multilayer substrate being processed according to a fourth embodiment of the present invention;

FIG. 8 is a schematic diagram of a reflection optical system including a polarization beam splitter and a quarter-wave plate according to a fifth embodiment of the present invention.

FIG. 9 is a schematic diagram illustrating a state of the intensity of the laser light.

FIG. 10 is a schematic diagram when a wavelength filter according to a sixth embodiment of the present invention is used.

FIG. 11 is a schematic view of a conventional laser processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 1st scanning mirror 3 2nd scanning mirror 4 Processing condensing lens 5 Beam splitter 6 Reflection light detector 7 Scanning mirror controller 8 Processing object moving mechanism 9 Arithmetic processing unit 10 Multilayer substrate 11 1st 12 Insulating layer 13 Second conductive layer 14 Output laser light 15 Reflected laser light 16 Laser light 17 Processing hole 18 Rear light detector 19 Rear laser light 20 Detector 21 Reflected laser light with different optical path 22 Cylindrical reflector 23 Vaporized material 24 scattered material 25 gas flow 26 polarizing beam splitter 27 quarter-wave plate 28 s-polarized laser light 29 circularly-polarized laser light 30 circularly-polarized laser light 31 p-polarized laser light 32 wavelength filter 101 laser oscillator 102 laser beam 103 Bend mirror 105 Workpiece 108 NC unit 115 Beam split Motor 116 reflected light 117 detector 118 monitors the laser light 119 detector

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H01S 3/10 H05K 3/00 N H05K 3/00 3/46 N 3/46 G02B 27/00 Q (72) Inventor Kazuhide Izaji Osaka No. 1006 Kadoma, Kamon, Fumonma-shi Matsushita Electric Industrial Co., Ltd. (56) References JP-A-4-361886 (JP, A) JP-A-2-92482 (JP, A) JP-A-4-45593 (JP, A) JP-A-1-48691 (JP, A) JP-A-59-27791 (JP, A) JP-A-2-179376 (JP, A) JP-B-57-48316 (JP, B2) (58) Survey Field (Int.Cl. ⁷ , DB name) B23K 26/00 B23K 26/02 G01N 21/47 G02B 27/00 H01S 3/10 H05K 3/00 H05K 3/46

Claims (17)

(57) [Claims] 1. The light reflectances in the processing direction are different from each other.
Has a laminated structure including a layer to be processed and a layer to be processed
Laser processing device for processing a workpiece
A laser oscillator for emitting a laser beam scan, and a control device for controlling the laser oscillator, an optical system for propagating a previous SL laser light to the processing object, detects the intensity of the reflected light from the workpiece a detector for, and an optical system for propagating the reflected light to the detector, before Symbol controller detected by the processing region, it has reached the non-planned processing layer using said reflected light After that, at least one more
A laser processing apparatus that controls the laser oscillator so as to additionally irradiate the laser light so as to provide a predetermined processing light intensity composed of a loose laser light . 2. The processing target layer is a low reflectance layer having a relatively low reflectance, and the non- processing target layer is a high reflectance layer having a relatively high reflectance. Features
The laser processing apparatus according to claim 1, wherein By 3. A state of increased intensity of reflected light is changed, the processing region, the laser processing apparatus according to claim 1 or 2 wherein detecting the arrival at the non-processing scheduled layer. 4. The laser processing apparatus according to claim 3, wherein a change in the state of increase in the reflected light intensity is detected using a time differential coefficient of the reflected light intensity. 5. A control device, the processing area after it is detected that has reached the non-processing scheduled layer, controls the laser oscillator to emit laser light to impart the processing light intensity obtained in advance The laser processing device according to claim 1 . 6. The control device, after detecting that the processing region has reached the non-processing scheduled layer, has detected the total light intensity of the laser beam that can be used for processing and reaching the non-processing planned layer. The laser processing apparatus according to any one of claims 1 to 4, wherein the laser oscillator is controlled so as to emit a laser beam so as to provide a processing light intensity corresponding to a difference between the reflected light intensity and the light intensity. And a rear detector for detecting the light intensity of the laser beam emitted from the rear side of the laser oscillator, wherein the rear detector detects the light intensity of the reflected light from the workpiece. signal, a laser machining apparatus according to any one of claims 1 to 6, which is normalized by the signal detected by the rear detector. 8. A reflector having a cylindrical shape having a pair of end portions through which reflected light can pass, in front of a detector for detecting the light intensity of the reflected light from the object to be processed. The opening area of the front end of the pair of ends is larger than the opening area of the rear end of the pair of ends, and the inner surface is made of a material that can reflect reflected light. Claim 1
7. The laser processing apparatus according to any one of claims 1 to 6 . 9. The laser processing apparatus according to claim 8 , wherein the inner surface of the cylindrical reflector is formed of a polygon and / or a curved surface. 10. Furthermore, while the reflected light from at least workpiece is detected, from claim 1, further comprising a means for generating gas flow into the atmosphere in the vicinity of the workpiece 9
The laser processing device according to any one of the above. 11. Furthermore, while the reflected light from at least workpiece is detected, according to any of claims 1 to 10 having a gas flow suction means for sucking the atmosphere in the vicinity of the object Laser processing equipment. 12. An optical system for propagating a laser beam to a processing target, and an optical system for transmitting reflected light from the processing target to a detector, wherein a common polarization beam splitter, the polarization beam splitter, and the optical system. claim 1, characterized in that to have a common quarter-wave plate disposed between the workpiece
12. The laser processing apparatus according to any one of items 1 to 11 . 13. A ray incident on a polarizing beam splitter.
The light is polarized light having a first polarization direction, and
Transmits through a light beam splitter and becomes circularly polarized by a quarter-wave plate
After being converted, it is reflected by the object to be processed and becomes reflected light,
The reflected light is the first polarization direction in the quarter-wave plate.
Converted into laser light having a different second polarization direction
The intensity of the reflected light with the polarizing beam splitter.
13. The laser processing apparatus according to claim 12 , wherein the laser beam is reflected in the direction of the emitted detector . 14. The laser processing apparatus according to claim 1, further comprising a wavelength filter in an optical path of the reflected light, the wavelength filter transmitting only the wavelength near the reflected light. 15. A processing step of processing an object to be processed by a pulsed laser beam, a detecting step of detecting a light intensity of light reflected from the object, and a processing area based on the light intensity of the reflected light in the detecting step. after There was detected that it has reached the non-processing scheduled portion of the workpiece, less further into the workpiece
Providing a predetermined processing light intensity consisting of one pulse of laser light . 16. The laser processing method according to claim 15, further comprising a processing light intensity calculating step of previously obtaining a predetermined processing light intensity. 17. A method according to claim 1, wherein the predetermined intensity corresponds to a difference between the total light intensity of the laser beam that can be used for the processing and the light intensity of the reflected light when it is detected that the processing region has reached the part to be processed. 2. A processing light intensity calculating step for obtaining a processing light intensity.
5. The laser processing method according to 5.