JP2001096390A - Method of cleaning contact mask for laser processing equipment and laser processing equipment with mask cleaning mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of cleaning the contact mask for a laser processing equipment which can remove adherent matters without removing a contact mask from the equipment. SOLUTION: This laser processing method comprises irradiating laser beams to a printed circuit board 20 by the contact mask method, through the contact mask 14-2 which has a processing pattern by a hole. The contact mask can move between a 1st position at which contacts with a printed circuit board and a 2nd position distant from the circuit board. By irradiating laser beams to the contact mask in such a state that a reflection mirror 1 intervals under the contact mask when the contact mask is at the above 2nd position, the deposit adherent to the contact mask can be removed.

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 suitable for drilling a resin layer such as a printed wiring board by a laser beam using a contact mask method, and more particularly to a method for cleaning a contact mask and a method for cleaning a contact mask. The present invention relates to a laser processing apparatus provided with a cleaning mechanism.

[0002]

2. Description of the Related Art With the miniaturization and high-density mounting of electronic equipment, printed wiring boards are required to have higher densities.
For example, a so-called interposer is known as a printed wiring board for mounting and packaging an LSI chip. The connection between such an LSI chip and an interposer has hitherto been mainly performed by a wire bonding method. However, a method called flip-chip mounting tends to increase, and the number of pins of a package is also increasing.

[0003] In accordance with such a tendency, it is necessary for the interposer to form a large number of via holes called small holes at a small pitch.

[0004] Such a drilling process is mainly performed by a mechanical process using a mechanical fine drill or an exposure (photo via) method, but recently, a laser beam has begun to be used. A drilling apparatus using a laser beam is superior to a mechanical processing using a fine drill in that the processing speed and the diameter of a hole can be reduced. As the laser light, a CO ₂ laser or a harmonic solid-state laser is generally used because the price and the running cost of the laser oscillator are low.

[0005]

In a conventional laser drilling apparatus, a laser beam from a laser oscillator is guided to a scanning optical system called an XY scanner or a galvano scanner through an optical path including a reflection mirror or the like. Drilling is performed by irradiating a laser beam with this scanning optical system and irradiating a printed wiring board through a processing lens (for example, see Japanese Patent Application Laid-Open No. 10-58).
178 publication). In other words, since the position of the hole to be drilled in the printed wiring board is predetermined,
Drilling is performed one by one by controlling the scanning optical system based on the positional information of these holes.

However, in the drilling of individual holes using a scanning optical system using an XY scanner or a galvano scanner, the processing time increases in proportion to the increase in the number of holes in the printed wiring board. Incidentally, since the response of the galvano scanner is about 500 pps, it is difficult to form holes of 500 holes or more per second. Also, for example,
50 μm on a square package substrate with a side of 10 mm
If holes of diameter are arranged at a pitch of 0.2 mm, 2
There are 500 holes. In this case, a processing time of 2500/500 = 5 sec is required even if 500 holes are drilled per second.

On the other hand, the present inventor has proposed a laser drilling method and a laser drilling apparatus for realizing a reduction in the drilling speed. As will be described in detail later, the laser drilling apparatus is a laser drilling apparatus that irradiates a substrate to be processed, such as a printed wiring board, with laser light to perform a plurality of drilling operations. A beam shaping means for shaping a laser beam from a laser oscillator into a linear or rectangular beam and a contact mask having a processing pattern with a plurality of holes, and the linear or rectangular beam is contacted through the contact mask. An optical system for irradiating a processing region of the substrate to be processed by a mask method, a mechanism for scanning the linear or rectangular beam with respect to the contact mask, and a table for mounting the substrate to be processed in an X-axis direction And an XY stage mechanism that moves the processing area by being movable in the Y-axis direction. Serial and performing a plurality of drilling a substrate to be processed.

In such a laser drilling apparatus, drilling is performed with the contact mask in contact with the printed wiring board. Since the drilling is performed by thermally decomposing the resin layer with a laser beam, the thermally decomposed carbide easily adheres to the contact mask. When the amount of deposits on the inner surface of the hole increases, the shape of the hole to be processed is distorted. In addition, if the amount of deposits on the lower surface side of the contact mask increases, the state of contact with the printed wiring board deteriorates, which also causes distortion in the hole to be processed. For this purpose, deposits on the contact mask must be removed periodically.

[0009] Such removal has hitherto been performed by a cleaning method using a so-called wet process, in which a contact mask is immersed in a special acidic treatment solution to remove deposits. However, in this method, it is necessary to periodically remove the contact mask from the optical system, clean the contact mask, and then attach the contact mask to the optical system again. In addition, special equipment for the wet process is separately required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of cleaning a contact mask for a laser processing apparatus, which can remove extraneous matter without removing the contact mask from the apparatus.

Another object of the present invention is to provide a laser processing apparatus with a mask cleaning mechanism that enables removal of attached matter while the contact mask is attached to the optical system.

[0012]

According to the present invention, there is provided a laser processing method for performing processing by irradiating a substrate to be processed with a laser beam through a mask. A method for cleaning a mask is provided, in which the mask is irradiated with a laser beam to remove deposits attached to the mask.

A method of cleaning a contact mask for a laser processing apparatus according to the present invention is directed to a laser processing method for performing processing by irradiating a substrate to be processed with laser light by a contact mask method through a contact mask having a processing pattern by holes. The contact mask is movable between a first position in contact with the substrate to be processed and a second position away from the substrate to be processed, and when the contact mask is at the second position, By irradiating the laser light to the contact mask with a reflection mirror interposed below the contact mask, the deposits adhering to the contact mask are removed.

The cleaning method is characterized in that the laser beam is shaped into a linear or rectangular beam, and the entire surface of the contact mask is scanned with the linear or rectangular beam.

According to the present invention, in a laser processing apparatus for performing processing by irradiating a substrate to be processed with laser light by a contact mask method through a contact mask having a processing pattern by holes, the contact mask is driven by a mask. A mechanism is movable between a first position in contact with the substrate to be processed and a second position away from the substrate to be processed, and a third position between the first position and the second position. And a reflecting mirror driving mechanism that makes the reflecting mirror movable between a fourth position deviated from the third position and a third mirror when the contact mask is at the second position. By irradiating the laser beam to the contact mask in a state where the reflection mirror is interposed in the position,
A laser processing apparatus with a mask cleaning mechanism is provided, which removes deposits attached to the contact mask.

The present laser processing apparatus particularly includes a laser oscillator, beam shaping means for shaping a laser beam from the laser oscillator into a linear or rectangular beam, and the contact mask having a processing pattern formed by a plurality of holes. hand,
An optical system that irradiates the linear or rectangular beam to a processing region of the substrate to be processed by the contact mask method through the contact mask, and a mechanism that scans the linear or rectangular beam with respect to the contact mask; By providing an XY stage mechanism for moving a processing area by making a table for mounting the processing substrate movable in the X-axis direction and the Y-axis direction, a plurality of substrates can be mounted on the processing substrate. Used as a drilling device.

In the laser processing apparatus, the optical system includes the contact mask at a lower end thereof, and the apparatus further moves the optical system up and down to move the contact mask to the first position and the first position. A Z-axis drive mechanism movable between the second position and the second position is provided as the mask drive mechanism.

When the substrate to be processed is a resin substrate, a CO ₂ pulse laser oscillator is used as the laser oscillator, the energy per pulse is 1 J or more, the pulse width is 10 μsec or less, and the frequency is 100 Hz or more. It is characterized by irradiating a shaped beam.

The sectional shape of the hole of the contact mask is as follows:
It is preferable to have an inverted trapezoidal shape in which the diameter on the upper surface side is larger than the diameter on the lower surface side.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser drilling apparatus to which the present invention is applied will be described with reference to FIG. The laser drilling apparatus has been proposed by the present inventor as Japanese Patent Application No. 11-259058 as described above. Hereinafter, a case in which a large number of holes are formed in a printed wiring board will be described. In particular, here, as will be described later, a case will be described in which the printed wiring board is prepared in the form of a motherboard for multiple-paneling.

Referring to FIG. 2, a laser drilling apparatus according to the present invention includes a TEA CO ₂ pulse laser oscillator (hereinafter, referred to as a laser oscillator) 10 and reflection mirrors 11 and 1.
And an optical path including 2 and 13. Reflection mirror 1
The beam shaping means for shaping the laser beam from the laser oscillator 10 into a linear beam having a size corresponding to one processing region on the printed wiring board 20 is provided in the optical path 3 and thereafter, An optical system 14 including a contact mask for irradiating the processing region of the package substrate 20 with a linear beam by a contact mask method;
Is arranged.

Referring to FIG. 3, the optical system 14 accommodates a cylindrical lens 14-1 as a beam shaping means, and has a contact mask 14-2 attached to a lower end portion. The optical system 14 is driven in a vertical direction (Z-axis direction) by a Z-axis driving mechanism (not shown), and the contact mask 14-2 is brought into contact with the printed wiring board 20 (to be in the first position) and separated from the printed wiring board 20 (first position) 2).

The contact mask 14-2 is formed by the optical system 14
X axis and Y axis via a θ axis adjusting mechanism (not shown)
It is mounted rotatably in a state parallel to the axis. The rotation angle is minute, and as for an example of the θ-axis adjustment mechanism, the contact mask 14-2 may be supported by the rotation axis at one corner thereof, and the rotation axis may be rotated by the driving mechanism. .

Referring to FIG. 4, contact mask 14-
Numeral 2 is for forming a large number of holes in the processing area of the printed wiring board 20, and has a processing pattern including a large number of transmission holes formed at a constant pitch. This processing pattern is the same as the pattern composed of a large number of holes formed in the processing area of the printed wiring board 20, but is not limited to the processing pattern shown in FIG.

In this embodiment, a mechanism is provided for scanning the contact mask 14-2 with a linear beam having a length in the same direction as or longer than the contact mask 14-2 in the uniaxial direction.
Scanning can be performed on the processing area of the printed wiring board 20. Such a scanning mechanism, for example,
This is realized by moving the reflection mirror 13 in the L-axis direction shown in FIG. 2, that is, in the incident direction of the linear laser beam. Since such a scanning mechanism can be realized by using a known technique, its illustration and description are omitted. The processing pattern of the contact mask 14-2 can be manufactured within an error range of about 3 μm.

Returning to FIG. 2, the laser drilling apparatus further mounts a chucking plate or table (not shown) having a function of chucking the printed wiring board 20, and mounts the chucking plate or table in the X-axis direction and the Y-axis direction. An XY stage mechanism 30 is provided to move the processing area of the printed wiring board 20 by making it movable. The XY stage mechanism 30 is attached to a frame (not shown). The XY stage mechanism 30 includes a linear motor for driving in the X-axis direction and a linear motor for driving in the Y-axis direction as driving sources, and measures a position in the X-axis direction and a position in the Y-axis direction. As means, a linear encoder for the X-axis direction and a linear encoder for the Y-axis direction are provided. Even in such an XY stage mechanism 30, the printed wiring board 20 can be positioned within an error of about 3 μm by a combination of an image processing device and a control device described later. Since the XY stage mechanism 30 is also well known, a detailed description is omitted.

In order to perform positioning control on the XY stage mechanism 30, an image processing device 40 is disposed above the printed wiring board 20 here. The image processing apparatus 40 includes an imaging device such as a CCD that captures an area in one processing area of the printed wiring board 20, a processing area of the printed wiring board 20 that processes an obtained image, and a contact mask placed thereon. An image processing unit for detecting a relative error between the contact mask 14-2 and the X-axis direction and the Y-axis direction and a position error in the rotation direction of the contact mask 14-2.

An example of a method for detecting such a relative error will be briefly described. On the printed wiring board 20,
An alignment mark is previously attached to a portion near the corner for each of the processing regions. Image processing device 40
Further, an image including the alignment mark around the processing area of the printed wiring board 20 is read by the cylindrical lens 14.
-1 has an optical path leading to the imaging device without passing through the imaging device. Such an optical path is achieved by disposing a mirror that transmits laser light and reflects visible light at an angle of 45 degrees between the cylindrical lens 14-1 and the contact mask 14-2 in the optical system 14. Can be easily realized. In the image obtained by the imaging device, the alignment mark is recognized in the image processing unit, and the X-axis direction and the Y-axis direction of the alignment mark are determined based on the result of comparison between the recognition result and a reference position set in advance on the image. And the positional deviation of the contact mask 14-2 in the rotation direction are detected as relative errors. Such a relative error is detected for all the alignment marks. In order to detect the displacement of the entire contact mask 14-2 in the X-axis direction and the Y-axis direction and the displacement of the contact mask 14-2 in the rotation direction, at least three alignment marks are required. Such a method of detecting a relative error is also well known.

A control device (not shown) controls the XY stage mechanism 30 based on the detected positional deviation amount to adjust the printed wiring board 20 so that the positional deviation amount in the X-axis direction and the Y-axis direction becomes zero. Perform alignment adjustment. The control device also calculates θ based on the amount of displacement in the rotation direction.
By controlling the axis adjusting mechanism, the position of the contact mask 14-2 is adjusted so that the amount of displacement in the rotational direction of the contact mask 14-2 becomes zero.

The XY stage mechanism 30 is a two-axis control mechanism. In addition, the chucking plate itself may be mounted on the XY stage mechanism 30 via a θ-axis adjustment mechanism so that the chucking plate itself can be rotated by a small angle. Such a chucking plate with a θ-axis adjustment mechanism is also well known as a θ table. In this case, the printed wiring board 20 is located on a horizontal plane, that is, X
It is rotated in a state parallel to the axis and the Y axis. When such a chucking plate is provided, the above-described θ-axis adjustment mechanism for rotating the contact mask 14-2 is unnecessary.

The laser oscillator 10 is a pulse laser oscillator having a multi-mode beam profile as shown in FIG. 5A and having an energy per pulse of 1000 (mJ). The multi-mode beam profile is a trapezoidal waveform in which a constant energy value is maintained unlike a peak waveform beam profile having a single energy peak value. On the other hand, by using the cylindrical lens 14-1 as the beam shaping means, a laser beam having a circular cross section having a multi-mode beam profile can be formed as shown in FIG.
It can be shaped into a linear beam as shown in FIG. According to the cylindrical lens, the size of the linear beam is set to a width of 1/10 (mm) to a number (mm) and a length number (c).
m). A well-known optical system called a beam expander is arranged between the reflection mirrors 12 and 13 so that the laser beam from the laser oscillator 10 is shaped into a sectional shape that can be easily shaped by the cylindrical lens 14-1. May be.

Drilling according to this embodiment is usually performed for each processing area on a printed wiring board 20 made of a resin material for multi-panel formation, in which a plurality of processing areas 21 are defined, as shown in FIG. The printed wiring board 20 has an X-
It is mounted on a chucking plate provided on the Y stage mechanism 30.

Next, the case where drilling is performed using a linear beam will be described. The basic operation is as follows.

1. The printed wiring board 20 is mounted on a chucking plate of the XY stage mechanism 30.

2. The image processing device 40 recognizes the alignment mark on the processing area 21 of the printed wiring board 20, recognizes the position of the processing area 21, and determines the X-axis direction, the Y-axis direction, and the θ direction (rotation of the contact mask 14-2). Direction) is calculated.

3. The XY stage mechanism 30 is controlled so that the first processing area 21 on the printed wiring board 20 is directly below the contact mask 14-2.

4. The θ-axis adjusting mechanism is controlled to correct the positional deviation of the contact mask 14-2 in the θ-direction.

5. The contact mask 14-2 is set on the processing area 21 by the Z-axis drive mechanism.

6. The laser oscillator 10 is oscillated, and the linear beam is moved in the L-axis direction by the scanning mechanism to irradiate the entire pattern of the contact mask 14-2.

7. When irradiation of the entire pattern is completed, Z
The contact mask 14-2 is moved upward by the shaft driving mechanism.

8. The printed circuit board 20 is moved by the XY stage mechanism 30 so that the next processing area 21 is directly below the contact mask 14-2.

9.2 and subsequent steps are repeated. The correction of the displacement for each processing area 21 is performed for the following reason. Normally, in the processing of the second and subsequent processing areas 21, the position shift correction operation is not required. This is because the positioning error by the XY stage mechanism 30 is 3 μm as described above.
This is because the pitch of the holes formed in the processing region 21 is sufficiently larger than the above-mentioned error, and such an error does not matter. However, in practice, when the above-described processing is performed on the plurality of processing areas 21, the printed wiring board 20 may be distorted due to the influence of heat or the like, resulting in a non-negligible displacement.

Drilling is performed by the basic operation as described above. However, by using the cylindrical lens 14-1 as the beam shaping means, the width is reduced to 1/10 (mm) or more.
As described above, a linear beam having a number (mm) and a length (cm) can be obtained. For example, when a linear beam from the cylindrical lens 14-1 is projected onto the processing area 21 with a size of 0.6 mm in width and 30 mm in length, it is suitable for a processing area of a square having a side of 30 mm.
That is, in this case, by scanning the linear beam in the L-axis direction by the scanning mechanism described above,
The linear beam scans the entire surface of the square processing area in the L-axis direction. Strictly speaking, the linear beam scans the contact mask 14-2 in a uniaxial direction.

The laser drilling apparatus according to this embodiment irradiates the linear beam as described above through the contact mask 14-2 to the processing area 21 of the printed wiring board 20 while scanning the same, thereby forming a large number of holes in this irradiation area. Can be opened all at once.

Hereinafter, a specific example will be described.

The laser oscillator 10 has an average output 30
0 W, energy per pulse is 1 J or more, preferably 2 J, pulse width is 10 μsec or less, preferably 0.2 μsec, and frequency is 100 Hz or more, preferably 150 Hz. Then, the energy density on the processing surface is set to ² J / cm ² or more.

On the other hand, holes are formed in one processing region 21 with a small diameter and a high density such that the pitch is 0.2 to 0.3 mm and the diameter is 50 to 150 μm.

For example, if holes having a diameter of 50 μm are arranged at a pitch of 0.2 mm in a square processing area 21 having a side of 10 mm, there are 2500 holes.

A feature of the laser drilling apparatus according to the present embodiment is that a multi-hole processing method is employed instead of a single-hole processing method. In the case of drilling a processing area 21 of a printed wiring board 20 having a thickness of 40 μm such as an epoxy resin,
The processing surface has an energy density of 10 J / cm ² and can be processed in three shots. With such a linear beam,
The spot size is (2/10) = 0.2 cm ² , 150
0.2 × (150/3) = 1 per second due to Hz oscillation
Drilling can be performed in a processing area of 0 cm ² .
Therefore, when 2500 holes are drilled in a square processing area 51 having a side of 10 mm (1 cm ² ), the processing time is 1
/ 10 = about 0.1 sec.

On the other hand, in the case of the one-hole processing method (galvano scanner method), as described above, the response time of the galvano scanner is about 500 pps. / 500 =
5 seconds.

Next, a case where a rectangular beam is used instead of the linear beam will be described. Cylindrical lens 1
By using a condenser lens instead of 4-1, FIG.
It can be shaped into a rectangular beam as shown in FIG. In this case, the beam size is about several mm on one side. The laser drilling device in this case is the above L
The axial scanning mechanism cannot cover the entire area of the contact mask 14-2 only by scanning in one axial direction. Therefore, a two-axis scan mechanism is used instead of the L-axis direction scan mechanism. That is, by moving the reflecting mirror 13 in the L-axis direction and a direction perpendicular to the L-axis direction by the two-axis scanning mechanism, the rectangular beam scans the entire area of the contact mask 14-2 so that the processing area 21 of the printed wiring board 20 is scanned. , A large number of holes can be made in this irradiation area.

For example, when the size of the contact mask 14-2 is a square with a side of 10 mm and the cross-sectional size of the rectangular beam projected on the contact mask 14-2 through the condenser lens is a square with a side of 5 mm, FIG. As shown in FIG. 7, the contact mask 14-2 has four regions 1
4-2a to 14-2d are equally divided. First, at least one pulse-shaped rectangular beam is applied to the region 14-2a.
Irradiation is performed once, and the number of holes determined by the processing pattern of the region 14-2a is collectively formed in the processing region 21 immediately below the region 14-2a. Next, the rectangular beam is moved by the biaxial scanning mechanism so that the rectangular beam comes to the area 14-2b, and a hole is made just below the area 14-2b. Less than,
Similarly, drilling is performed immediately below the areas 14-2c and 14-2d. Here, the number of times of irradiation of one area with the pulsed rectangular beam is determined according to the material and thickness of the resin layer to be perforated, as described above.

In order to enable the above-described scanning, a control device (not shown) controls the two-axis scanning mechanism and outputs a trigger pulse for determining the oscillation period of the pulse to the laser oscillator 10.

Conditions of Laser Oscillator 10 and Processing Area 21
In the case where drilling is performed on the processing area 21 by assuming that the conditions described above are the same as those of the linear beam described above, for example, when processing is performed at 8 J / cm ² , the size of the rectangular beam is changed to a square shape having a side of 5 mm. It can be. In this case, as described with reference to FIG. 7, the region of the contact mask 14-2 is divided into four parts and drilling is performed in order. And 8J / c
In the case of m ² , since drilling can be completed in about 10 shots for one divided region, the laser drilling time for a divided region having a side of 5 mm is 10/150 Hz = 66 m
sec. On the other hand, the time required for moving to the next divided area by the two-axis scanning mechanism is 1
00 msec or less.

Therefore, when 2500 holes are drilled in a square processing area 21 having a side of 10 mm, the processing time is 6 hours.
6 msec × 4 = 0.264 sec.

Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 8 shows a case where a printed wiring board 20 having a conductive pattern 20-1 made of Cu or the like formed on one surface is prepared, and the opposite surface corresponding to the conductive pattern 20-1 is drilled by irradiating a laser beam. Is shown. Drilling pattern is contact mask 14
-2 is determined by a processing pattern formed by a plurality of holes 14-2e formed in the second hole. As described above, the printed wiring board 20
When the resin layer is irradiated with laser light, the resin layer is thermally decomposed and evaporated. At this time, it is inevitable that the carbide generated during the thermal decomposition adheres to the inner surface of the hole 14-2e and the lower surface of the contact mask 14-2.

In FIG. 1, contact mask 14-2
Is driven up and down by a Z-axis drive mechanism. That is, the contact mask 14-2 is in the first position (FIG. 1) in contact with the surface of the printed wiring board 20 during the drilling process.
(Indicated by a dashed line). On the other hand, when the processing area is moved or cleaned, the processing area is located at a second position (shown by a solid line in FIG. 1) away from the surface of the printed wiring board 20.

In the present embodiment, as shown in FIG. 1, between the first position and the second position of the contact mask 14-2 (this is referred to as a third position), the third There is provided a reflection mirror driving mechanism 2 which makes the reflection mirror 1 movable between a position and a fourth position deviated therefrom. The reflection mirror drive mechanism 2 includes a reflection mirror 1 having a reflection surface facing upward.
Reciprocating rotation in the horizontal state (direction perpendicular to the plane in FIG. 1)
It may be a rotating mechanism provided with a motor or the like for driving, or a driving mechanism provided with a cylinder mechanism or the like for moving the reflecting mirror 1 reciprocally (horizontal direction in FIG. 1) while keeping it horizontal.

In any case, the reflection mirror driving mechanism 2
When cleaning, contact mask 14-
2 is in the second position, the contact mask 14-2
Is placed in a state where the reflection mirror 1 is interposed at the third position directly below the third position. Then, in this state, the contact mask 14-2
The contact mask 1 is irradiated by irradiating the
The attached matter attached to 4-2 is removed. Such cleaning is performed periodically.

Of course, the laser beam is applied to the entire surface of the contact mask 14-2 by a scanning mechanism in the form of a linear or rectangular beam, as in the case of the above-described drilling. In this case, the contact mask 14-2
The deposits adhering to the inner diameter surface of the hole 14-2e are instantaneously sublimated and removed. In particular, since the reflection mirror 1 is located immediately below the contact mask 14-2, the laser light that has passed through the hole 14-2e is reflected by the reflection mirror 1 and is irradiated on the lower surface side of the contact mask 14-2. Deposits attached to the lower surface of the contact mask 14-2 are also removed. Contact mask 14-2
Deposits on the lower surface of the contact mask 14-
Since the contact between the printed wiring board 2 and the printed wiring board 20 is hindered, it is important to remove it. Further, by making the cross-sectional shape of the hole 14-2e of the contact mask 14-2 into an inverted trapezoidal shape in which the diameter on the upper surface side is larger than the diameter on the lower surface side, the laser light can be spread over the entire inner surface of the hole 14-2e. Since the irradiation is performed, the effect of removing the deposits attached to the inner diameter surface of the hole 14-2e can be improved. In particular, hole 14-2e
Since the edge on the lower surface side affects the quality of the hole formed in the printed wiring board, it is important to remove the deposits attached to this edge.

As described above, in the case of drilling in the processing area 21 of the printed wiring board 20, the energy density of the processed surface is 10 J / cm ² and several shots are required. 5 J / cm ² or less is sufficient, and the number of shots may be fixed.

Although the above embodiment has been described by applying to the case of drilling a hole in a printed wiring board, the member to be processed is not limited to the resin layer of the printed wiring board. Further, the laser oscillator is not limited to the TEA CO ₂ laser oscillator, but may be an ultraviolet laser oscillator, for example.

[0063]

As described above, according to the present invention, a contact mask in a laser processing apparatus capable of performing a large number of drilling operations in a short time as compared with a conventional laser drilling apparatus is used in an optical system. It is possible to realize the removal of the attached matter while keeping it attached.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a mask cleaning mechanism according to the present invention.

FIG. 2 is a diagram showing an example of a schematic configuration of a laser drilling apparatus to which the present invention is applied.

FIG. 3 is a diagram showing an internal configuration of the optical system shown in FIG. 2;

FIG. 4 is a diagram showing an example of a contact mask used in the present invention.

5 is a diagram showing a beam profile of a laser beam used in the present invention and a sectional shape of the laser beam by the beam shaping means shown in FIG. 3;

FIG. 6 is a diagram showing a mother board of a printed wiring board to be processed by a laser drilling apparatus to which the present invention is applied;

FIG. 7 is a view for explaining a method in a case where a contact mask is divided into four regions and scanned using a rectangular beam in a laser drilling apparatus to which the present invention is applied.

FIG. 8 is a cross-sectional view illustrating a case in which a laser drilling apparatus to which the present invention is applied performs drilling on a printed wiring board.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 reflection mirror 2 reflection mirror drive mechanism 10 TEA CO ₂ laser oscillator 11-13 reflection mirror 14 optical system 14-1 cylindrical lens 14-2 contact mask 20 printed wiring board 21 processing area 30 XY stage mechanism 40 image processing device

Claims (9)

[Claims] 1. A laser processing method for performing processing by irradiating a substrate to be processed with laser light through a mask, wherein the mask is irradiated with laser light in a state where a reflection mirror is interposed below the mask. And a method of cleaning a mask, comprising removing a substance attached to the mask. 2. A laser processing method for performing processing by irradiating a processing target substrate with laser light by a contact mask method through a contact mask having a processing pattern by holes, wherein the contact mask contacts the processing target substrate. A movable state between a first position and a second position separated from the substrate to be processed, and a state in which a reflection mirror is interposed below the contact mask when the contact mask is at the second position; Irradiating the contact mask with the laser beam to remove the deposits attached to the contact mask. 3. The cleaning method according to claim 2, wherein the laser beam is shaped into a linear or rectangular beam, and the entire surface of the contact mask is scanned with the linear or rectangular beam. For cleaning a contact mask for a laser processing apparatus. 4. A laser processing apparatus for performing processing by irradiating a processing target substrate with laser light through a mask, wherein the processing is performed by irradiating the mask with laser light in a state where a reflection mirror is interposed below the mask. And a laser processing apparatus with a mask cleaning mechanism, which removes deposits attached to the mask. 5. A laser processing apparatus for performing processing by irradiating a processing target substrate with laser light by a contact mask method through a contact mask having a processing pattern by holes, wherein the contact mask is processed by a mask driving mechanism. Movable between a first position in contact with the substrate and a second position remote from the substrate to be processed, a third position between the first position and the second position, A reflecting mirror driving mechanism for moving the reflecting mirror between a fourth position deviating from the third position and the reflecting mirror at the third position when the contact mask is at the second position; A mask cleaning mechanism for irradiating the contact mask with the laser beam in a state where a laser beam is interposed therebetween to remove the deposits attached to the contact mask. With laser processing equipment. 6. A laser processing apparatus according to claim 5, wherein the processing pattern includes a laser oscillator, a beam shaping means for shaping a laser beam from the laser oscillator into a linear or rectangular beam, and a plurality of holes. An optical system that irradiates the linear or rectangular beam to a processing area of the substrate to be processed by the contact mask method through the contact mask, and the linear or rectangular beam. A mechanism for scanning with respect to the contact mask; and an XY stage mechanism for moving a processing region by moving a table for mounting the substrate to be processed in the X-axis direction and the Y-axis direction. A laser processing apparatus with a mask cleaning mechanism, wherein a plurality of holes are formed in the substrate to be processed. 7. The laser processing apparatus according to claim 6, wherein the optical system includes the contact mask at a lower end thereof, and the apparatus further moves the optical system up and down to remove the contact mask. A laser processing apparatus with a mask cleaning mechanism, comprising a Z-axis drive mechanism movable between a first position and the second position as the mask drive mechanism. 8. The laser processing apparatus according to claim 5, wherein the substrate to be processed is a resin substrate,
A CO ₂ pulse laser oscillator is used as the laser oscillator, and the linear or rectangular beam is irradiated at an energy per pulse of 1 J or more, a pulse width of 10 μsec or less, and a frequency of 100 Hz or more. Laser processing equipment. 9. The laser processing apparatus according to claim 5, wherein a cross-sectional shape of the hole of the contact mask is an inverted trapezoidal shape in which a diameter on an upper surface is larger than a diameter on a lower surface. A laser processing device with a mask cleaning mechanism.