JP2014226715A - Discharge auxiliary type laser hole machining method, and method of manufacturing insulating substrate having through hole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge auxiliary type laser hole machining method which can significantly suppress a projection generated around an opening of a through hole after machining as compared with a conventional one.SOLUTION: A discharge auxiliary type laser hole machining method forms a plurality of through holes on an insulating substrate by laser beam irradiation, and adjusts a shape of the through hole by a discharge phenomenon between first and second electrodes. The discharge auxiliary type laser hole machining method forms the through hole in an irradiation region of the insulating substrate by irradiating the insulating substrate with a laser beam, and then a DC voltage is applied between the first and second electrodes before power of the laser beam in the irradiation region becomes zero to generate discharge in the irradiation region.

Description

  The present invention relates to a discharge assist type laser hole machining method and a method for manufacturing an insulating substrate having a through hole.

  Conventionally, a technique for forming a through hole in an insulating substrate by irradiating the insulating substrate with laser light from a laser light source via a laser optical system is known.

  Recently, a technique for making a through hole in an insulating substrate using a laser melting type discharge removing technique has been disclosed (for example, Patent Document 1). In this method, the through hole can be formed in the insulating substrate by combining the laser beam irradiation and the interelectrode discharge phenomenon.

International Publication No. WO2011 / 038788

  As described above, in the laser melting type discharge removal technique, after the insulating substrate is melted by laser light irradiation, the insulating material melted by the interelectrode discharge phenomenon is removed, and a through hole can be formed in the insulating substrate.

  Here, in the conventional laser melting type discharge removal method, there is often a problem that no discharge occurs at an appropriate place in the discharge after the laser light irradiation. For example, when a laser beam is irradiated to the through hole formation target position and an electric discharge is generated at the through hole formation target position by the inter-electrode discharge, the discharge is not generated at the through hole formation target position and is already formed. Discharge may occur through the formed through hole (existing through hole). When such a phenomenon occurs, discharge does not occur at the through hole formation target position, so that the through hole is not formed at the through hole formation target position, and excess energy is input to the existing through hole. There may be a problem that cracks occur in the through holes.

  Moreover, in the conventional laser melting type electric discharge removal technique, a protrusion may be generated around the opening of the through hole after processing. Such protrusions can cause problems when the through hole is filled with a conductive member and electrical wiring is formed on the surface of the insulating substrate. That is, when such a protrusion is present on the surface of the insulating substrate, it becomes difficult to form a continuous wiring in the vicinity of the through hole filled with the conductive member, causing a problem that the wiring is disconnected. obtain.

  The present invention has been made in view of such a background. In the present invention, cracks are less likely to occur in the through hole than in the prior art, and the protrusions generated around the opening of the processed through hole are significantly suppressed. An object of the present invention is to provide a discharge assist type laser drilling method that can be used.

According to the present invention, there is provided a discharge assisted laser hole machining method in which a plurality of through holes are formed in an insulating substrate by laser light irradiation, and the shape of the through hole is adjusted by a discharge phenomenon between the first and second electrodes. There,
By irradiating the insulating substrate with laser light, after the through hole is formed in the irradiation region of the insulating substrate, before the power in the irradiation region of the laser light becomes zero, the first and second electrodes A discharge assisted laser hole machining method is provided, wherein a discharge is generated in the irradiation region by applying a DC voltage therebetween.

Here, in the discharge assist type laser hole machining method according to the present invention, when the time when the power in the irradiation region of the laser beam becomes zero is defined as time zero,
The discharge may occur at a timing between −140 μsec and −60 μsec.

  Further, in the discharge assisted laser hole machining method according to the present invention, after the power in the irradiation region of the laser beam becomes zero, the insulating substrate is disposed around the opening of the through hole formed in the insulating substrate. A protrusion having a maximum height from the surface of 0.95 μm or less may be formed.

  In the discharge-assisted laser hole machining method according to the present invention, the insulating substrate may be a glass substrate.

Furthermore, in the present invention, a method of manufacturing an insulating substrate having a through hole,
By irradiating the insulating substrate with laser light, a through-hole is formed in the irradiation region of the insulating substrate, and then facing through the insulating substrate before the power in the irradiation region of the laser light becomes zero. A method is provided comprising the step of generating a discharge in the irradiated region by applying a DC voltage between the two electrodes.

  According to the present invention, it is possible to provide a discharge-assisted laser hole machining method that is less likely to cause cracks in the through hole than in the prior art and that can significantly suppress protrusions that occur around the opening of the through hole after machining.

It is the figure which showed schematically an example of the structure of the laser melting type electric discharge removal apparatus. It is the figure which showed an example of the protrusion which arises in the insulated substrate after a through-hole process. It is the figure which showed typically an example of the timing of each process in the discharge assistance type laser hole processing method by this invention. It is the figure which showed roughly the flow of the 1st electric discharge auxiliary | assistant type laser hole processing method by one Example of this invention. It is the figure which showed collectively the timing chart of each process in each example. It is the graph which showed collectively the relationship of the timing of discharge generation in each example, and the height of protrusion.

  Hereinafter, the present invention will be described with reference to the drawings.

(Conventional laser melting discharge removal technology)
To better understand the present invention, first, a conventional laser melting type discharge removal technique will be briefly described with reference to FIG.

  FIG. 1 schematically shows an example of the configuration of a general laser melting type discharge removing apparatus used in a conventional laser melting type discharge removing technique.

  Here, in this application, “laser melting type discharge removal technology” is a technology in which an insulating substrate is melted by laser light irradiation, and then the insulating material melted by an interelectrode discharge phenomenon is removed to form a through hole in the insulating substrate. Means.

  On the other hand, the “discharge assist type laser hole processing method (technique)” means that a through hole is formed in the irradiation region of the insulating substrate by laser light irradiation to the insulating substrate as shown below, and then the interelectrode discharge phenomenon Means the generic name of the technique for adjusting the shape of the through hole. The adjustment of the hole shape means that necking that occurs when a plurality of through holes are formed in the insulating substrate by laser light irradiation is reduced. Here, “necking” means a protruding portion that can be formed in the through hole after laser processing.

  As shown in FIG. 1, a conventional laser melting type discharge removing apparatus 100 includes a laser light source 110, a laser optical system 120, a DC high-voltage power supply 125, a first electrode 140, and a second electrode 145.

  The laser light source 110 has a role of irradiating the laser light 113 toward the laser optical system 120. The laser optical system 120 may include, for example, a lens as shown in FIG. The laser optical system 120 has a role of converging the laser beam 113 emitted from the laser light source 110 to the through hole forming position 183 of the insulating substrate 190.

  The first electrode 140 and the second electrode 145 are electrically connected to the conductors 150 and 155, respectively, and these conductors 150 and 155 are connected to the DC high-voltage power source 125.

  The first electrode 140 and the second electrode 145 are different in shape and arrangement form. In other words, the first electrode 140 has a needle shape and is arranged away from the insulating substrate 190. On the other hand, the second electrode 145 has a substantially flat plate shape and is disposed immediately below the insulating substrate 190 so as to be in contact with the insulating substrate 190. The second electrode 145 can also serve as a stage on which the insulating substrate 190 is placed.

  However, this is merely an example, and the second electrode 145 may be disposed, for example, directly below the insulating substrate 190 and separated from the insulating substrate 190. The second electrode 145 may have a needle shape similar to that of the first electrode 140. In this case, a set of electrode pairs is configured between the first electrode 140 and the second electrode located opposite to each other with the insulating substrate 190 interposed therebetween.

  When the through-hole processing is performed on the insulating substrate 190 using such a laser melting type electric discharge removing apparatus 100, the insulating substrate 190 is first disposed between the electrodes 140 and 145. Further, the insulating substrate 190 is disposed at a predetermined position by moving the stage (which may be the second electrode 145) in the horizontal direction.

  Next, the laser beam 113 is irradiated from the laser light source 110 toward the laser optical system 120. The laser beam 113 is converged by the laser optical system 120 to become an irradiation laser beam 115. This irradiation laser beam 115 is applied to the irradiation region 183 of the insulating substrate 190.

  As a result, the temperature of the irradiation region 183 of the insulating substrate 190 rises locally, and a melted portion is formed immediately below.

  Next, after the irradiation of the irradiation laser beam 115 is completed, a DC high voltage is applied between the electrodes 140 and 145 using the DC high-voltage power supply 125. Thereby, discharge occurs between the electrodes 140 and 145. Discharge tends to occur through the fusion zone. Due to the occurrence of electric discharge, the melted portion becomes the through hole 185.

  Next, the stage is moved in the horizontal direction, and the insulating substrate 190 is disposed at a predetermined location. Thereafter, the second through hole is formed by the same process.

  By repeating such steps, a plurality of through holes can be formed in the insulating substrate 190.

  Here, when the through-hole processing is performed on the insulating substrate 190 by such a method, a protrusion may often be generated around the opening of the through-hole 185 after processing.

  FIG. 2 shows an example of such protrusions generated on the glass substrate. As shown in FIG. 2, a ring-shaped protrusion is formed around the opening of the through hole provided in the glass substrate. The height of the protrusion is about 1.0 μm or more.

  Such protrusions can then be a problem when the insulating substrate is applied as a member of various products. For example, when an insulating substrate is used as an interposer, it is necessary to form electrical wiring on the surface of the insulating substrate after filling the through hole with a conductive member. However, if there are protrusions as shown in FIG. 2 on the surface of the insulating substrate, it becomes difficult to form continuous wiring in the vicinity of the through hole filled with the conductive member, and the wiring is disconnected. Problems can arise.

In order to cope with such a problem, the inventors of the present application have conducted intensive research and development on a mechanism in which a protrusion is generated around the opening of the through hole and a method for suppressing the generation of the protrusion. As a result, the inventors of the present application
(I) When the projection generates a discharge through the through-hole by applying a DC high voltage, a part of the melt in the through-hole has a surface tension with the surface of the insulating substrate. As a result of remaining without being completely dissipated from the substrate, it was found that it was highly likely to be formed, and (ii) that this protrusion could be remelted by irradiation with laser light, leading to the present invention. .

That is, in the present invention,
A discharge assist type laser hole processing method for forming a through hole in an insulating substrate by combining laser light irradiation and a discharge phenomenon between first and second electrodes,
By irradiating the insulating substrate with laser light, after the through hole is formed in the irradiation region of the insulating substrate, before the power in the irradiation region of the laser light becomes zero, the first and second electrodes A discharge assisted laser hole machining method is provided, wherein a discharge is generated in the irradiation region by applying a DC voltage therebetween.

  In the present invention, the discharge due to the application of the DC high voltage is performed before the power in the laser light irradiation region becomes zero. In other words, the laser light irradiation is continued even after the discharge due to the application of the DC high voltage.

  In this case, even if a protrusion is formed around the opening of the through-hole due to the discharge, the protrusion is remelted by the laser light irradiation that continues after the discharge. For this reason, in this invention, the height of the processus | protrusion produced around the opening of a through-hole after a process can be suppressed significantly. For example, in the discharge assisted laser hole machining method according to the present invention, the height of the protrusions generated around the opening of the through hole of the insulating substrate after machining can be suppressed to less than 1.0 μm, for example, 0.95 μm or less.

  Thereby, in the discharge assisted laser hole machining method according to the present invention, the problem that the wiring is disconnected due to the protrusion when the electrical wiring is formed on the surface of the processed insulating substrate can be significantly suppressed.

  In an actual discharge assist type laser drilling apparatus, the time (timing) when a command to stop the irradiation of the laser beam is given to the apparatus, and the laser beam is not actually irradiated (the laser beam in the irradiation region). There is a time lag (displacement) of, for example, about 60 μs to 75 μs during the time (timing) when the output becomes zero).

  However, such a time lag is measured by measuring the time until the output of the laser beam actually becomes zero in the irradiation region after giving a command to stop the irradiation of the laser beam using a power meter or the like. Accurately grasp. Therefore, in the present application, the time when the irradiation region of the insulating substrate is not actually irradiated with the laser beam (the laser beam output becomes zero in the irradiation region) is defined as 0 (zero) on the time axis.

  Based on this rule, in the present invention, the discharge due to the application of the DC high voltage is 0 second after the time when the through hole is formed by the laser light irradiation on the time axis (hereinafter referred to as “penetration time Tp”). It will be implemented at a timing between less than.

  FIG. 3 shows a schematic timing chart of a laser beam irradiation process and a discharge process applied in the present invention.

  As shown in FIG. 3, the laser light irradiation step (I) is performed until time 0 (zero), and is stopped here. In addition, the discharge process (II) by applying a DC high voltage is performed in a time shorter than 0 (μ seconds) after the penetration time Tp (μ seconds).

  The discharge generation timing Te (μ seconds) may be the same as the penetrating time Tp (that is, Te = Tp), but includes the case of time 0 (zero), that is, the same timing as the completion of laser light irradiation. It should be noted that this is not possible. This is because in the latter case, the effect (ii) described above cannot be obtained.

  In FIG. 3, the left end (lower limit value) of the timing Te (μ seconds) at which discharge is possible is indicated by ● in the discharge process by applying DC high voltage in (II) so that this is clear. The right end (upper limit) of the timing Te (μ seconds) at which discharge is possible is indicated by ◯.

  In particular, it is preferable that the discharge generation timing Te (μ seconds) in the discharge process by applying a DC high voltage (II) is generated at a timing of −140 μsec or more and −60 μsec or less on the time axis. (In FIG. 3, it is necessary to note that the left end (lower limit value) of the preferable range and the right end (upper limit value) of the preferable range of discharge generation timing Te (μ seconds) are both indicated by ●. .) When the discharge is generated at such timing, the height of the protrusion formed around the opening of the through hole can be further suppressed.

  Further, the value of the penetration time Tp (μ seconds), that is, the length from the penetration time Tp (μ seconds) to the time 0 is not particularly limited, but the value of the penetration time Tp (μ seconds) is, for example, −200 μ It may be in the range of not less than seconds and less than -140 μs.

(About the discharge assist type laser drilling method according to one embodiment of the present invention)
Next, with reference to FIG. 4, a discharge assisted laser hole machining method (first discharge assisted laser hole machining method) according to an embodiment of the present invention will be described.

  FIG. 4 shows a schematic flow diagram of the first discharge-assisted laser hole machining method according to the present invention.

As shown in FIG. 4, the first discharge assist type laser hole machining method is as follows.
(1) A step of forming a through hole in the irradiation region of the insulating substrate by irradiating the insulating substrate with laser light (Step S110);
(2) Next, generating a discharge in the irradiation region by applying a DC voltage between the first and second electrodes (step S120);
(3) Next, stopping the irradiation of the laser beam and setting the power of the laser beam in the irradiation region of the insulating substrate to zero (step S130);
Have

  Hereinafter, each step shown in FIG. 4 will be described in detail.

  Note that the laser melting type electric discharge removing apparatus 100 shown in FIG. 1 can also be used as a discharge assist type laser hole processing apparatus. Therefore, here, the laser melt type discharge removing device 100 shown in FIG. 1 described above is replaced with the discharge assist type laser hole processing device 100, and the first discharge assist type using the discharge assist type laser hole processing device 100 is used. Each step will be described by taking as an example the case of implementing the laser beam drilling method.

(Step S110)
First, the insulating substrate 190 is disposed on the second electrode 145 of the discharge assist type laser hole processing apparatus 100.

  The type of the insulating substrate 190 is not particularly limited, and the insulating substrate 190 may be, for example, a glass substrate. Further, the thickness of the insulating substrate 190 is not particularly limited, and the insulating substrate 190 may have a thickness of 0.05 mm to 0.7 mm, for example.

  In addition, a resin film may be provided on at least one surface of the insulating substrate 190. By installing a resin film on the surface of the insulating substrate 190, it is possible to suppress processing dust (debris) from adhering to the surface of the insulating substrate 190 after processing.

Next, the laser beam 113 is irradiated from the laser light source 110 toward the laser optical system 120. The laser light source 110 may be, for example, a CO ₂ laser source.

  The laser light 113 from the laser light source 110 is converged by a laser optical system 120 having one or more lenses, and becomes an irradiation laser light 115. This irradiation laser beam 115 is applied to the irradiation region 183 of the insulating substrate 190. The focal spot diameter of the irradiation laser beam 115 in the irradiation region 183 is, for example, in the range of 10 μm to 300 μm.

  As a result, the temperature of the irradiation region 183 of the insulating substrate 190 rises locally to sublimate the glass, and a through hole 185 is formed here.

  As shown in FIG. 3, the time for which the through hole is formed in the insulating substrate 190 is defined as a through time Tp (μ seconds).

(Step S120)
Next, a DC high voltage is applied between the first electrode 140 and the second electrode 245 by the DC high-voltage power supply 125. The applied voltage is, for example, in the range of 3000V to 10000V. Thereby, a discharge occurs in the through hole 185, and the shape in the through hole 185 is adjusted.

  Note that a protrusion is formed around the opening of the through-hole 185 by the discharge.

(Step S130)
Next, the irradiation of the irradiation laser beam 115 is stopped. That is, the power of the irradiation laser beam 115 in the irradiation region 183 of the insulating substrate 190 becomes zero.

  Through the above steps, the through hole 185 is formed in the irradiation region 183 of the insulating substrate 190.

  Here, when the insulating substrate 190 having the through-hole 185 is manufactured in such a procedure, as described above, the protrusion generated on the insulating substrate 190 in step S120 is irradiated with the irradiation laser beam 115 that continues until step S130. To remelt.

  Therefore, after step S130, the height of the protrusion generated around the opening of the through hole 185 can be significantly reduced.

  As described above, the discharge generation timing in step S120 is in the range of −140 μsec to −60 μsec when the timing at which the power of the irradiation laser beam 115 becomes zero in step S130 is the zero point on the time axis. It is preferable that Thereby, the height of the protrusion can be further suppressed.

  The reason why the height of the protrusion can be significantly reduced after the completion of step S130 by setting the discharge generation timing Te in step S120 to any one between −140 μs and −60 μs is not clear so far. Absent. However, the height of the protrusion is expected to depend on the irradiation time of the laser beam that is continuously irradiated even after the occurrence of discharge.

  The embodiment of the present invention has been described above by taking as an example the case where the first discharge-assisted laser drilling method is performed using the discharge-assisted laser drilling apparatus 100 as shown in FIG.

  However, the discharge-assisted laser hole machining method of the present invention may be performed using, for example, another discharge-assisted laser hole machining apparatus.

  For example, although not shown in FIG. 1, some discharge assisted laser drilling devices have a high frequency (HF) high voltage power supply. Such a discharge assisted laser hole machining apparatus may be used to carry out the discharge assisted laser hole machining method of the present invention.

  In this case, an HF voltage may be applied between the first electrode 140 and the second electrode between the aforementioned step S110 and step S120. That is, in step S110, after the irradiation of the irradiation laser beam 115 is started (for example, after a through hole is formed in the irradiation region 183), HF application is started. Thereafter, only the HF application is stopped without stopping the irradiation with the irradiation laser beam 115, and then the discharge process is performed in step S120.

  Next, examples of the present invention will be described.

(Example 1)
Using the discharge assist type laser hole machining apparatus as shown in FIG. 1 described above, an insulating substrate having a through hole was manufactured by the first discharge assist type laser hole machining method shown in FIG. 4 described above.

  A glass substrate (non-alkali glass) having a thickness of 0.3 mm was used as an insulating substrate. A resin film for preventing debris was placed on the first surface (laser light irradiation side) and the second surface (opposite side of the first surface) of the glass substrate.

A CO ₂ laser source was used as the laser light source. The output of the irradiation laser beam was 50W. The irradiation time of the irradiation laser light was set to 800 μsec. In Example 1, the time for forming a through-hole in the glass substrate by the irradiation laser beam, that is, Tp is expected to be about 650 μsec after the irradiation laser beam irradiation starts.

  A dc voltage of 5000 V was impressed between the two electrodes 660 μsec after the start of irradiation with the irradiation laser beam, and a discharge was generated in the irradiation region.

  Thereafter, the discharge assist type laser hole processing apparatus was instructed to stop the irradiation of the irradiation laser beam, and after 800 μs from the start of the irradiation of the irradiation laser beam, the irradiation of the laser beam in the irradiation region was completely stopped. Incidentally, the timing To of the irradiation stop command of the irradiation laser light is about 740 μs after the irradiation start of the irradiation laser light.

  Thereby, the glass substrate (glass substrate which concerns on Example 1) which has a through-hole was manufactured. The diameter of the opening of the through hole was about 70 μm.

  By the same method, the through-hole was formed in each of three different irradiation areas with respect to the same glass substrate.

In addition, according to the above-mentioned definition, when the timing at which the laser beam output becomes zero in the irradiation region is defined as 0 (zero) on the time axis, each timing is as follows:
Penetration time Tp = −150 μsec;
Timing of occurrence of discharge Te = −140 μsec;
Irradiation laser beam irradiation stop command timing To = −60 μsec.

(Examples 2 to 5)
A glass substrate having through holes at three locations was produced in the same manner as in Example 1.

  In Example 2, however, a direct current voltage of 5000 V was impressed between the two electrodes 700 μs after the start of irradiation with the irradiation laser beam, and a discharge was generated in the irradiation region. In Example 3, after irradiating the irradiation laser light, a direct current voltage of 5000 V was impressed between the two electrodes after 720 μsec to generate a discharge in the irradiation region. Further, in Example 4, after 740 μsec from the start of irradiation with the irradiation laser light, a DC voltage of 5000 V was impressed between the two electrodes to generate a discharge in the irradiation region. Moreover, in Example 5, after starting irradiation of the irradiation laser light, a DC voltage of 5000 V was impressed between the two electrodes 770 μsec later, and a discharge was generated in the irradiation region.

  Other conditions are the same as in Example 1. Thereby, the glass substrate which concerns on Examples 2-5 was manufactured.

(Example 6 to Example 8)
A glass substrate having through holes at three locations was produced in the same manner as in Example 1.

  However, in Example 6, a direct current voltage of 5000 V was impressed between the two electrodes 800 μs after the start of irradiation with the irradiation laser light, and a discharge was generated in the irradiation region. Further, in Example 7, after irradiating the irradiation laser light, a direct current voltage of 5000 V was impressed between the two electrodes 830 μsec, and a discharge was generated in the irradiation region. In Example 8, after 920 μsec from the start of irradiation with the irradiation laser light, a DC voltage of 5000 V was impressed between the two electrodes, and a discharge was generated in the irradiation region.

  Other conditions are the same as in Example 1. Thereby, the glass substrate which concerns on Examples 6-8 was manufactured.

  FIG. 5 shows a timing chart of each process in each example. In FIG. 5, each timing is shown with the timing at which the output of the laser beam becomes zero in the irradiation region as the zero point on the time axis.

  As is clear from FIG. 5, Examples 1 to 5 are examples, and Examples 6 to 8 are comparative examples.

(Evaluation)
In the manufactured glass substrate according to Examples 1 to 8, the height of the protrusions generated around the opening of the through hole was measured. For the measurement, a laser microscope (VK-X200SERIES; manufactured by Keyence Corporation) was used, and laser light was irradiated from the first surface of the glass substrate to measure the height of the protrusion.

  In any glass substrate, the height of the protrusions was measured on the protrusions formed around each of the three through holes. At this time, the maximum value of the measured heights of the projections in each through hole was defined as the height H of the projection of the through hole. Furthermore, the value Have obtained by averaging the heights H of the three protrusions was defined as the height of the protrusions of the glass substrate.

  In FIG. 6, height Have of the protrusion obtained in each glass substrate which concerns on Examples 1-8 is shown collectively. In FIG. 6, the horizontal axis represents the discharge generation timing Te (μ seconds) in each example, and the vertical axis represents the height Have (μm) of the protrusion.

  From the results of FIG. 6, it can be seen that in the glass substrates according to Examples 1 to 5, the height Have of the protrusions is significantly suppressed as compared with the glass substrates according to Examples 6 to 8. That is, in the glass substrates according to Examples 6 to 8, the height Have of the protrusions is about 1.0 μm, whereas in the glass substrates according to Examples 1 to 5, the height Have of the protrusions. Is 0.95 μm or less at the maximum.

  In particular, in the glass substrates according to Examples 1 to 4, the height Have of the protrusion is 0.75 μm or less, and it was found that the height of the protrusion can be further reduced.

  Thus, it was confirmed that the height of the protrusion can be significantly suppressed by setting the discharge generation timing Te (μ seconds) to less than 0 seconds after the penetration time Tp (μ seconds). In particular, it was confirmed that the height of the protrusion can be further suppressed by setting the discharge generation timing Te (μ seconds) to be between −140 μ seconds (Example 1) to −60 μ seconds (Example 4).

  The present invention can be used for a technique for forming a through hole in an insulating substrate such as a glass substrate.

100 Laser melting type discharge removing device (discharge assist type laser drilling device)
DESCRIPTION OF SYMBOLS 110 Laser light source 113 Laser light 115 Irradiation laser light 120 Laser optical system 125 DC high voltage power supply 140 1st electrode 145 2nd electrode 150, 155 Conductor 183 Irradiation area 185 Through-hole 190 Insulating substrate

Claims (5)

A discharge assist type laser hole machining method, wherein a plurality of through holes are formed in an insulating substrate by laser light irradiation, and the shape of the through hole is adjusted by a discharge phenomenon between the first and second electrodes,
By irradiating the insulating substrate with laser light, after the through hole is formed in the irradiation region of the insulating substrate, before the power in the irradiation region of the laser light becomes zero, the first and second electrodes A discharge assist type laser hole machining method, wherein a discharge is generated in the irradiation region by applying a DC voltage between them. When the timing at which the power in the irradiation region of the laser beam becomes zero is determined as time zero,
The discharge-assisted laser drilling method according to claim 1, wherein the discharge is generated at a timing between −140 μs and −60 μs.   After the power in the irradiation region of the laser beam becomes zero, a protrusion having a maximum height of 0.95 μm or less from the surface of the insulating substrate is formed around the opening of the through hole formed in the insulating substrate. The discharge-assisted laser drilling method according to claim 1 or 2, wherein:   The discharge-assisted laser hole processing method according to any one of claims 1 to 3, wherein the insulating substrate is a glass substrate. A method of manufacturing an insulating substrate having a through-hole,
By irradiating the insulating substrate with laser light, a through-hole is formed in the irradiation region of the insulating substrate, and then facing through the insulating substrate before the power in the irradiation region of the laser light becomes zero. A method comprising the step of generating a discharge in the irradiation region by applying a direct current voltage between two electrodes.