JP2003088983A - Device for laser drilling, method for manufacturing multilayer wiring substrate and multilayer wiring substrate using the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for laser drilling which copes with a multilayer wiring substrate and other high machining position accuracy in which a fine or accurate hole position or hole shape is required, and to provide a method for manufacturing a multilayer wiring substrate and a multilayer wiring substrate using the method. SOLUTION: The laser drilling device, the method for manufacturing the multilayer wiring substrate and the multilayer wiring substrate using the method are provided. The laser drilling device is characterized by the features that the device is composed of a drilling unit on which a laser beam which is emitted from a laser oscillator 1 is focused on a work to be machined 9 and the work is drilled, a test unit for machining position accuracy, a means which transmits correction data induced from the machining from the machining unit to the test unit for machining position accuracy and a means which transmits correction data based on the test result from the test unit for machining position accuracy to the machining unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser drill device for forming holes for interlayer connection to upper and lower wiring layers sandwiching an insulating layer by a laser beam, and rigid or flexible multilayer wiring using the device. The present invention relates to a board manufacturing method and a multilayer wiring board manufactured by the manufacturing method.

[0002]

2. Description of the Related Art In recent years, the performance of semiconductors has dramatically improved, and the number of terminals of semiconductors has increased. However, since the motherboard, which is a printed wiring board in a hard disk of a computer, and the printed wiring board, which is used in mobile terminals and mobile phones, are limited in area, the size of a semiconductor package, which is a wiring board on which a semiconductor is mounted, is limited.

In order to mount a semiconductor having a large number of terminals, the wiring board is required to have finer wiring, in other words, to have a higher density. However, since the manufacturing method is difficult, the wiring board can be multi-layered. Measures are being taken to mitigate the thinning of the line. At the time of this multi-layering, by forming a hole in the insulating layer and coating a conductive metal material in the hole, interlayer connection between the upper and lower metal wiring layers sandwiching the insulating layer is achieved, and an electrical multi-layer wiring is formed. It is possible.

Conventionally, machining with a metal drill has been the mainstream for forming holes for interlayer connection. However, if the hole has a very small diameter, it must be processed by a drill, of course
In addition, it was a consumable item that was severely worn during processing. In recent years, laser drilling, in which high-energy laser light is irradiated and absorbed by a processing target to be heat-processed, has come to be used in place of the mechanical processing of a metal drill for forming the micropores. Thereby, in order to perform interlayer connection of the wiring layers of each layer which are multi-layered in the high-density wiring board, a method of irradiating the insulating layer with laser light to form a hole and filling the inside of the hole with a metal substance is adopted. .

The laser processing technique is used in various industrial fields, and there are gas lasers, solid-state lasers, semiconductor lasers, and the like in accordance with the principle of laser oscillation as the type of laser.
These lasers are used in a wide variety of fields, such as the electronics field, which utilizes processing such as cutting and forming holes in metals, and the medical field, which irradiates energy up to the sublimation point of organic substances and is used for treatment. In particular, CO ₂ laser, which is one of gas lasers, and ultraviolet laser, which is a wavelength-converted solid-state laser, have emerged in the field of electronic equipment industry because they can form micropores.

The laser light used for laser drilling is a CO ₂ laser (wavelength 9.3 to 10.6 μm) in the infrared region.
m), YAG laser (fundamental wavelength 1.06 μm),
YAG, YLF, YAP, YVO ₄ lasers in the ultraviolet range (3rd harmonic wavelength 355 nm, 4th harmonic wavelength 2
66 nm) and excimer laser (wavelength 3 of XeCl
08 nm, KrF wavelength 248 nm, ArF wavelength 19
3 nm) is currently used as a laser beam for a drilling machine. Laser processing using wavelengths in the infrared region is thermal processing or pyrolysis processing, as opposed to mechanical processing in metal drills, and laser processing using wavelengths in the ultraviolet region is called photolysis processing using photochemical reactions.

The mainstream of machining using a metal drill is the formation of through-holes, but since laser machining is pulsed, only the insulating layer can be machined. Therefore, laser processing is mainly used for blind hole processing of wiring boards, that is, non-through hole processing. At present, the CO ₂ laser has a diameter of 50 to 150 μm, and the ultraviolet laser has a diameter of 30 to 80, which is used for differentiating the hole diameters by various laser lights.
μm. The excimer laser can process a finer diameter such as φ20 μm, but it is not suitable for mass production because consumables such as a highly reflective metal oxide film mask and maintenance of laser medium gas are expensive.

However, regarding the above-mentioned segregation, formation of holes by an ultraviolet laser is considered to be promising as the density of wiring boards increases. As a result, the holes formed by laser light can have a diameter of 100 μm or less, which cannot be achieved by metal drilling, and it is now possible to form minute holes of 20 to 50 μm due to technological development in a laser drilling machine.

When the object of laser drilling is only the resin insulating layer, it is possible to form holes with CO ₂ and an ultraviolet laser. However, the metal wiring layer and the resin insulating layer are simultaneously processed, that is, the direct processing step is performed. When employed, a CO ₂ laser cannot be drilled because the laser light is not absorbed by the metal layer and is almost reflected because it is not in the absorption wavelength range of the metal wiring layer.

On the other hand, since the wavelength of the ultraviolet laser overlaps with the absorption wavelength of metal, direct processing, which is direct processing on metal, is possible. Moreover, since the energy density is high, laser processing is possible even with a small diameter. As a result, in the conventional hole formation, the hole was formed in the insulating resin layer and the wiring layer above the hole was formed after filling the inside of the hole, but when the wavelength band is in the ultraviolet region, the laser light is also absorbed by the metal. Therefore, it is possible to simultaneously form holes in the metal layer + insulating resin layer. Therefore, by directly processing from the metal layer, the manufacturing process can be significantly shortened and the productivity is improved.

In the hole formation by the ultraviolet laser, CO ₂
Since it is possible to form holes with a diameter smaller than that of lasers, it is considered to be a promising candidate for the next-generation high-density wiring board manufacturing. At present, there is a problem that the processing capacity is low, but due to the multi-axis of the processing head, the high oscillation frequency of laser light, etc., it is possible to supply at low cost by mass production. Ultraviolet lasers have the ability to outperform CO ₂ lasers for small diameters of φ50 μm or less.

An outline of a laser drilling device using an ultraviolet laser beam will be described below with reference to FIG. The laser light resonated in the oscillator is converted from a fundamental wave (wavelength 1.06 μm) into a second harmonic (wavelength 526 nm) and a third harmonic (wavelength 355 nm) by a wavelength conversion crystal.

If the wavelength is further converted, the fourth harmonic (wavelength 2
66 nm) is obtained. The ultraviolet laser light 2 output from the oscillator forms an image on the object to be processed through the optical axis path of the collimate lens 3 and the like, the galvano XY scan mirrors 6 and 7 and the fθ lens 8.

The Galvano XY scan mirror is a total reflection mirror, and scan processing is possible by scanning a certain area with respect to the target coordinates. Specifically, laser drilling is possible in all areas on the processing table by combining the galvano scan area and the moving mechanism of the XY table. In the hole formation using laser light, a certain area is scanned by a galvano XY scan mirror, and the laser light is imaged for each hole at the processing point. Therefore, the galvanometer mechanism has X-direction and Y-direction mirrors and can scan the processing point by changing the mirror angle in each axis.

The fθ lens is a scanned laser
Light is emitted as laser light that is vertically reflected on the processing table 10.
Adjust the road trajectory. Scanned by the Galvo mechanism
The galvano scan area, which is the area ₂laser,
30 x 30 mm to 50 x 50 mm for both UV lasers
It is degree.

The processing range is expanded over the entire surface of the processing table by adding the galvano scanning area to the movement range of the processing table. Of course, the processing head portion may serve one of the moving axes.

The response frequency of the Galvano XY scan mirror is about 1 kHz, and the mirror angle is controlled by an encoder or the like. However, since the laser light is scanned at the angle of the mirror and the vertical incident light path is formed by the fθ lens, the mechanical response accuracy of the mirror angle and fθ
Since the lens tolerance accuracy and the movement accuracy of the processing table are superposed, the coordinate position accuracy of the laser beam 13 has a variation 14 of ± 15 to 30 μm as shown in FIG.

In order to improve the processing capacity, it is not possible to exclude the scan processing method by the galvano mechanism, and therefore it is necessary to adopt a design rule considering the coordinate position accuracy of laser light. As a concrete design rule, the design value of the land diameter 15 that receives the via hole greatly reflects the coordinate position accuracy of laser drilling,
The size of the land diameter affects the wiring density. That is, within the limited area, the land diameter most hinders the number of wirings, and it is necessary to reduce the land diameter when considering high-density wiring.

The coordinate position accuracy of laser light has a certain degree of distribution. Specifically, since the processing is performed for each hole, the coordinate position accuracy (processing position accuracy) of the irradiation laser light has a certain distribution. This processing position accuracy distribution is about ± 20 μm from the design coordinates, which is affected by the optical coordinate reproducibility, the processing table position reproducibility, and the like. Further, since the optical design peculiar to the device is also affected, the processing position accuracy cannot be discussed unconditionally.

The processing position accuracy in the hole formation greatly reflects the land diameter design. In other words, if the processing position accuracy is high, the diameter of the land that is the target of the laser light can be reduced, and small-diameter lands can be designed even in the wiring design of semiconductor packages with a limited area, and more wiring can be formed between lands. You can do it.

The distribution of the processing position accuracy is not constant, and the optical parts, such as various lenses, are continuously operated.
The thermal expansion of the mirror and the like, the position reproducibility of the galvanometer mechanism and the processing table, etc. affect the distribution of position accuracy, which changes over time. In other words, since there is a change on the optical axis path such as thermal expansion of the optical component due to continuous operation, the coordinate position accuracy as shown in FIG. 3 changes with time from the distribution 16 at the beginning of operation as shown in FIG. 4 and FIG. Changes to.

Therefore, the current operation system guarantees the processing position accuracy by setting a threshold value of the processing position accuracy, grasping the continuous operation time within that range, and performing the position calibration for each operation time. is doing. Therefore, the conventional operation method is to provide a coordinate position accuracy threshold value, stop continuous operation before reaching the threshold value, and put the device in an offline state, and then perform position accuracy calibration.

Although this calibration depends on the difference in threshold value, it is approximately 2 in order to guarantee the coordinate position accuracy.
Approximately once every 4 hours. If the position calibration is not performed, the positional accuracy deviations may be integrated over time and deviate from the design land as shown in 17 of FIG. Since holes for via holes are formed by laser drilling, the positional accuracy over time during processing has an effect, and if the holes come off the lands, interlayer connection cannot be established and the wiring board cannot be a product.

In this case, in order to verify the position accuracy, it is ideal to statistically correct the position accuracy with respect to the total number of processed holes. However, considering the processing speed, the tendency in the population is grasped to some extent. It is desirable to use the method
Currently not done.

Further, when the holes are formed in the wiring board, the board itself may shrink due to the influence of the previous process or the like. For this reason, it is impossible to obtain high positional accuracy without correcting the error from the design value due to the shrinkage of the substrate and processing. The substrate shrinkage differs for each substrate and each pattern, and the correction amount is always different.

This is because the substrate often shrinks from the design value (CAD data) depending on the wet processing and the transportation mode. If contracted, the amount of contraction must be calculated and drilled at the corrected coordinate value based on the result when drilling after taking in the position alignment according to the degree of contraction. Otherwise, the amount of shrinkage of the board will also overlap with the position accuracy as an error, and there is a possibility that it will further deviate from the land.

In order to correct the coordinate position deviation over time, the same optical axis as the laser beam for processing is shared by providing a half mirror, and visible light is projected to observe the deviation of the processing position immediately after processing. For example, Japanese Patent Laid-Open No. 8-
Proposed in 118055.

While observing the processing light and the inspection light on the optical axis can grasp the positional deviation amount of the total number of holes, the processing light cannot irradiate the object to be processed during the observation, and therefore the processing speed is high. Is reduced. This is because the galvano XY scan mirror must be stopped at that angle at the same coordinate position as the processing position when the incident light is emitted to detect the position accuracy.

Further, the observation in the coaxial optical path includes many steps in which the inspection light is reflected, the image of the reflected light is taken in, the image processing is performed to calculate the deviation amount, and the correction information is transmitted to the XY processing table. Even if the delay time caused by this is several seconds for one hole, there is a large number of hole coordinates on the entire surface of the substrate, and therefore the delay during long-time operation is considerable. In drilling, which is processing for each hole, when processing and observing coaxially, there is a problem that it is difficult to solve while either processing is being performed while the other is waiting.

Further, it is not necessary to correct the coordinate position deviation of each hole in each processing. This is because the amount of deviation in the galvano scan area does not increase significantly for each hole, but is gradually integrated during continuous operation, and it is sufficient to correct the position coordinates after a certain time interval. .

It may be possible to also serve as a residue inspection generated during resin processing. However, in the case of an ultraviolet laser, energy up to the sublimation point of the resin can be applied, and therefore residue residue is greatly increased compared to a CO ₂ laser. Problems can be largely eliminated. This is because it is possible to grasp the degree of residue on the entire surface of the substrate only by performing a certain sampling inspection.

[0032]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. For example, the multilayer wiring board as described above and other fine or accurate hole positions and hole shapes are provided. A laser drilling device and a method for manufacturing a multilayer wiring board, which correspond to a required high processing position accuracy, and a multilayer wiring board using the same.

For example, in laser drilling a hole portion for a via hole, a laser drilling apparatus having a processing unit and a processing position accuracy inspection unit and exchanging information about the amount of shrinkage of a substrate and the correction amount of a coordinate position is representative. It is to provide a device and the like.

[0034]

In order to achieve the above object in the present invention, in the invention of claim 1, first, a laser beam from a laser oscillator is imaged on an object to be processed and a drill is performed on the object to be processed. A drilling processing unit for processing, a processing position accuracy inspection unit, a means for transmitting correction data due to processing from the processing unit to the processing position accuracy inspection unit, and a correction based on the inspection result from the processing position accuracy inspection unit to the processing unit A laser drill device characterized by comprising means for transmitting data.

Thus, the apparatus for performing the processing position accuracy inspection can be provided with high accuracy without stopping the processing.
In particular, since the machining position accuracy inspection itself can use the correction data resulting from the machining, the accuracy of the correction data based on the inspection result can be increased.

Further, in the invention of claim 2, the processing unit and the processing position accuracy inspection unit in the laser drilling apparatus share the same CAD data, and the substrate shrinkage amount at the time of processing is processed from the processing unit to the processing position accuracy inspection unit. The laser drilling device according to claim 1, further comprising means for transmitting an offset value of a coordinate in which a machining position deviation amount is corrected from the position accuracy inspection unit to the machining unit.

Therefore, the same CAD data can be shared, and it is possible to further improve the accuracy of data exchange between the processing unit and the processing position accuracy inspection unit based on the data. is there.

According to the third aspect of the present invention, the machining position accuracy inspection unit transmits to the machining unit the offset value of the coordinate in which the machining position deviation amount is corrected from the inspection result inspected by the machining head in outline during machining. The laser drill device according to claim 1 or 2.

As a result, since the offset value takes into consideration the data from the inspection result inspected during the processing, the offset value becomes highly responsive and the processing accuracy is further enhanced. There is something.

Further, in the invention of claim 4, the processing position accuracy inspection unit transmits to the processing unit an offset signal obtained by calculating and correcting the amount of deviation from the target coordinate position in consideration of the amount of shrinkage of the substrate, and the processing unit corrects it. 4. The laser drilling device according to claim 1, wherein the laser drilling device is a drilling unit that performs drilling at a position where the target coordinate position is corrected based on the offset signal.

As a result, since the offset value takes into consideration the amount of shrinkage of the substrate, it is possible to cope with a change in the middle of processing, and the processing accuracy is further enhanced, which is an effect unique to claim 4.

The invention according to claim 5 is characterized in that the output light from the laser oscillator is ultraviolet laser light having a wavelength of a wavelength-converted third harmonic or more. It is a laser drill device. As a result, there is an effect unique to claim 5 that direct processing, which is direct processing on the metal, is possible because it overlaps with the absorption wavelength of the metal.

According to the invention of claim 6, the laser drill device according to any one of claims 1 to 5 forms an image of a laser beam from a laser oscillator on an object to be processed consisting of upper and lower wiring layers sandwiching an insulating resin layer. When performing the drilling, the machining position accuracy inspection unit, means for transmitting the correction data due to machining from the machining unit to the machining position accuracy inspection unit, and the compensation based on the inspection result from the machining position accuracy inspection unit to the machining unit A method of manufacturing a multilayer wiring board, characterized in that a hole forming step for connecting upper and lower layers sandwiching an insulating resin layer is performed by controlling a processing position by means of transmitting data. .
As a result, there is an effect unique to claim 6 that it is possible to easily form holes in the multilayer wiring board.

According to a seventh aspect of the present invention, there is provided a multilayer wiring board characterized in that holes are formed by the hole forming step according to the sixth aspect. As a result, there is an effect unique to claim 7 that a multilayer wiring board having a high hole accuracy can be obtained.

[0045]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the laser drilling apparatus of the present invention will be described below with reference to an example of a multilayer wiring board.

A drilling unit for forming a laser beam from a laser oscillator on the object to be processed to perform drilling on the object, a processing position accuracy inspection unit,
The processing unit includes means for transmitting correction data resulting from processing to the processing position accuracy inspection unit, and means for transmitting correction data based on the inspection result from the processing position accuracy inspection unit to the processing unit. The processing unit is the same as that described in the conventional example, and various types can be adopted.

The processing position accuracy inspection unit comprises a CCD camera and a computer connected to the CCD camera. Further, the distance from the position alignment mark of this pattern may be inspected even if the pattern for verifying the position accuracy is not provided in advance.

The position accuracy inspection method in the processing position accuracy inspection unit is a pattern for position accuracy verification based on CAD data, for example, distance coordinates from a position alignment mark are subjected to image processing on a computer using a CCD camera or the like. It is conceivable that the calculated result is used as an offset value and information is transmitted to the processing unit by an electric signal.

The pattern for verifying the position accuracy is a distance coordinate from the position alignment mark in the following example. The contents of the image processing in this case include extracting the position alignment mark from the CCD image, reading the distance coordinate of the position alignment mark in the XY coordinate system, and verifying the position accuracy based on the distance coordinate of the position alignment mark and the CAD data. The position accuracy is obtained by obtaining the difference between the distance coordinates of the pattern for each axis.

For the machining position accuracy inspection, it is ideal to correct the statistical position accuracy for all the machined holes, but a method for grasping the tendency in the population to some extent in consideration of the processing speed. It is desirable to take.

In addition to this pattern, an inspection pattern, which is a pattern for grasping the positional accuracy of hole formation by a laser drill, is arranged, and the processing position accuracy inspection unit determines the processing position deviation amount of only that portion. It is also possible to perform hole machining and position accuracy inspection simultaneously by calculating and continuously transmitting correction data to the machining unit.

An example of means for transmitting correction data resulting from machining from the machining unit to the machining position accuracy inspection unit and means for transmitting correction data based on the inspection result from the machining position accuracy inspection unit to the machining unit will be described below.

A scaling value, which is correction data based on the amount of shrinkage of the substrate on the processing unit side, and an offset value, which is position correction data based on the coordinate deviation amount of the processing position calculated by the processing position accuracy inspection unit, are exchanged with each other. Thus, the offset value corresponding to the scaling value can be calculated and used in the subsequent processing.

As a result, if the machining position accuracy for a certain scaling value deviates from the design value by ΔX, ΔY, the coordinates will be closer to the design coordinates by correcting the coordinates −ΔX, −ΔY. It is also possible to determine the degree of adoption of the scaling value with respect to the offset value.

When the degree of adoption is 100%, it means that the shrinkage amount is directly scaled. In a laser drill device including a galvanometer mechanism and a positional deviation inherent in the device, high machining position accuracy may be obtained when a 100% scaling value is not always followed. The machining position coordinates gradually approach the design coordinates by finely adjusting the scaling value and the offset value.

By constantly exchanging information between the scaling value and the offset value between the processing unit and the processing position accuracy inspection unit, it is possible to always obtain the minimum value of the time-dependent deviation of the processing position accuracy during continuous operation of the laser drill device. In addition, the step of stopping the continuous operation and performing the position calibration offline can be omitted.

In the processing unit, it is possible to correct the offset value from the processing position accuracy inspection unit by the moving mechanism of the processing table or the galvano XY mirror. Either one of the correction methods may be used by making use of the design peculiar to the apparatus, or both of the correction methods may be adopted.

Further, a time difference of several seconds to several tens of seconds is conceivable from the processing to the inspection of the same pattern, but it is unlikely that the processing accuracy of the laser is significantly deteriorated by such a time difference. Further, since the processing position accuracy inspection unit is a separate mechanism from the processing unit, each can be independently driven. The machining position accuracy inspection unit and the machining unit may be integrated into one device or may be separate devices.

As described above, the means for transmitting the correction data due to the processing from the processing unit to the processing position accuracy inspection unit and the means for transmitting the correction data based on the inspection result from the processing position accuracy inspection unit to the processing unit are laser The machining unit and the machining position accuracy inspection unit in the drill device share the same CAD data, and the amount of board shrinkage during machining is transferred from the machining unit to the machining position accuracy inspection unit.
The processing position accuracy inspection unit may be provided with a unit for transmitting the offset value of the coordinate corrected for the processing position deviation amount from the processing unit to the processing unit.

Of course, the data is not limited to the CAD data as long as the reference position can be accurately grasped without using the CAD data, and the type does not matter as long as the data can define the processing position. Further, although it is possible to eliminate the need for common data depending on how to hold both transmission data, it is easier to share the CAD data in order to simplify the means.

Therefore, the means for transmitting the correction data due to the processing does not necessarily have to transmit the substrate shrinkage amount at the time of processing or the following scaling value itself, but data considering the substrate shrinkage amount, such as position data, etc. But of course it doesn't matter.

Similarly, the correction data based on the inspection result is
The means for transmitting the correction data based on the inspection result from the processing position accuracy inspection unit does not necessarily need to transmit the processing position deviation amount or the following offset value itself, and data including the processing position deviation amount, for example, the position Of course, data or the like is also acceptable.

Therefore, it is also possible to transmit from the machining position accuracy inspection unit to the machining unit an offset value of the coordinates in which the machining position deviation amount is corrected from the inspection result inspected by the machining head during machining.

Further, the processing position accuracy inspection unit calculates the amount of deviation from the target coordinate position in consideration of the substrate contraction amount from the processing unit, and the processing unit corrects the target coordinate position based on the corrected offset signal. A configuration that is a drilling unit that performs drilling at different positions is also possible. Further, since the output light from the laser oscillator is an ultraviolet laser light whose wavelength is converted to a wavelength equal to or higher than the third harmonic, high speed processing is possible.

When this device is applied to a method for manufacturing a multilayer wiring board, laser light from a laser oscillator is imaged on an object to be processed consisting of upper and lower wiring layers with an insulating resin layer sandwiched between them to perform drilling. Processing by the position accuracy inspection unit, means for transmitting correction data due to processing from the processing unit to the processing position accuracy inspection unit, and means for transmitting correction data based on the inspection result from the processing position accuracy inspection unit to the processing unit By controlling the position, it is possible to perform a hole forming step for connecting the upper and lower layers sandwiching the insulating resin layer. With this method for manufacturing a multilayer wiring board, it is possible to supply a high-performance multilayer wiring board.

[0066]

EXAMPLES The contents of the laser drilling device of the present invention will be described below with reference to examples.

(Embodiment 1) A processing unit excites a YAG (yttrium-aluminum-garnet) crystal body with a semiconductor laser to generate a fundamental wave with a third harmonic (wavelength 3).
It has an optical system in which the ultraviolet laser light whose wavelength is converted to 55 nm) is condensed by a collimation lens, scanned by a galvano XY scan mirror, and the fθ lens is used to vertically irradiate the ultraviolet laser light on the processing table.

The scanning area of the Galvano XY scan mirror is 20 × 20 mm, and the size of the processing table is 300.
× 300 mm. The machining table is equipped with a drive in both XY directions, and is used in combination with the scanning area of the galvanometer mechanism to develop machining points on the entire surface of the machining table. The mechanical position reproducibility of the processing table is ± 5 μm.

The processing position accuracy inspection unit is a system that is equipped with an inspection suction table, a CCD camera for capturing an image, and a ring illumination and performs image processing by a computer on a monitor. The inspection speed is 2000 points per second. The distance between the processing unit and the processing position accuracy inspection unit is 80 cm so as not to interfere with the operation of the processing unit, and the processing table and the inspection table move in the same XY direction in conjunction with each other.

The scaling value and the offset value between the processing unit and the processing position accuracy inspection unit are electrically exchanged by a cable. That is, the scaling value is transmitted from the processing unit to the processing position accuracy inspection unit via the cable, and the offset value is transmitted in the opposite direction via the cable.

In the processing unit, the processing control software employs the offset value from the processing position accuracy inspection unit as the processing position data during processing. In the Galvano XY scan mirror, the laser light is first scanned by the mirror in the order of X → Y. The accuracy of the Galvano XY mirror is about ± 20 μm, and the processing table is ± 5 μm.
Is.

The position reproducibility of the machining table is more accurate than that of the galvanometer mechanism. Therefore, the offset value in the X direction is supported by the galvanometer mechanism, and the offset value in the Y direction is supported by the machining table, so that the overall machining position accuracy is obtained.

Both the flexible substrate and the rigid substrate were verified as the processing targets. The rigid board is an epoxy resin board having a total thickness of 2 mm. The flexible board is a polyimide tape board with double-sided copper foil and has a total thickness of 0.05 mm.
Is. In the transport system, magazine transport was performed for rigid substrates and roll transport was performed for flexible substrates. In magazine transportation, even if the processing unit and the processing position accuracy inspection unit are not interlocked with each other, there is no problem even if they are driven independently because one sheet is transferred to the processing unit and after processing, it is transferred to the processing position accuracy inspection unit.

On the other hand, since the flexible substrate has a tape shape, the processing unit and the processing position accuracy inspection unit are XY.
The driving directions were synchronized. Because the distance between the respective tables is as short as 80 cm, the independent driving causes the flexible substrate to be deformed such as excessive tension and twist. Therefore, in order to remove the load on these tapes, we constructed a transport system that synchronizes the movement direction of each table and provides a step which is the slack of the tape substrate between the tables.

Since the inspection attaches great importance to the influence of substrate shrinkage,
After applying a resist to the inspection substrate, a test pattern was formed by etching. Drill holes by laser drilling on the center of the land that is a circular pattern,
The machining position accuracy was inspected by calculating the amount of deviation between the center of the land and the hole. As image processing for inspection, pattern matching is performed on lands and holes to calculate respective barycentric coordinates, and a shift amount ΔX with respect to the coordinate system,
ΔY was calculated.

The substrate shrinks due to the pattern formation by etching. Therefore, during laser drilling, alignment, which is positioning, is performed, and scaling, which is correction that matches the shrinkage amount, is performed, and then drilling is performed.

This scaling value is correction data based on the amount of shrinkage of the substrate on the processing unit side, and is an example of correction data due to processing. In the processing apparatus, for example, pattern corners where alignment marks are arranged are provided. Image recognition is performed on each of the four locations, and the dimensions of the pattern outline in the X and Y directions are calculated. It is a value that can be obtained by calculating the pattern or substrate shrinkage amount from the design value and the measured value based on image recognition by comparison with CAD data.

Further, this scaling value is usually a value that can be displayed as a percentage, and is a value indicating the degree of dimensional agreement between the board in the ideal state (the board as designed) and the actual board. The holes in the pattern are processed based on the degree.

The degree of coincidence is a value having a relationship that it is often a similar shape of the area (range) in which the alignment mark is taken in. Therefore, when this scaling value is used in inspection, as a result of processing based on the degree of coincidence, the next adoption degree of scaling is fed back to the processing unit together with the offset value from the inspection result that is deviated by ΔX or ΔY. can do.

Also, in the processing apparatus, if the scaling values are deviated by ΔX and ΔY, when the coordinate correction of −ΔX and −ΔY is performed, the scaling value is multiplied and the actual correction is performed. It is also possible to multiply and determine the irradiation position.

Since the accuracy of scaling is also involved in the inspection of the processing position accuracy of the land by laser etching and the laser drill processing, a comparison was made with a substrate that has been subjected to conventional simple transfer processing as a reference.

Patterned substrates handled and transfer conditions,
The laser drill conditions are exactly the same. Further, the processing position accuracy was defined by the following formula, and the processing position accuracy only in the ordinary carrying processing and the processing position accuracy by the laser drilling device of the present invention were compared under continuous operation for 24 hours.

A rigid substrate and a tape substrate were adopted as inspection targets. The position calibration at the start of processing had the same accuracy. FIG. 6 shows the result of the present invention, and FIG. 7 shows the result when the conventional simple transfer processing is performed. The machining position accuracy parameter Δα is Δα = √ (ΔX
² + ΔY ² ).

[0084]

According to the laser drilling apparatus of the present invention, the correction data after the contraction of the substrate in the processing unit, for example, the position correction data based on the coordinate deviation amount of the scaling value and the processing position, for example, the offset value, are processed by the processing unit and processed. By electrically exchanging information between the position accuracy inspection units, drilling can always be performed based on the optimum scaling value and offset value.

That is, it is possible to guarantee the processing position accuracy of the laser drill during continuous operation. Further, since the machining position accuracy is guaranteed, the land diameter can be reduced, and a higher density wiring can be designed.

[Brief description of drawings]

FIG. 1 is a conceptual diagram illustrating a laser drill device according to the present invention.

FIG. 2 is a diagram showing a distribution of processing position accuracy in laser drilling.

FIG. 3 is a view showing a state before a change in processing position accuracy with time in laser drilling.

FIG. 4 is a diagram showing a change in the processing position accuracy over time in laser drilling when there is no position correction data.

FIG. 5 is a view showing a state after a change in processing position accuracy with time in laser drilling when there is position correction data.

FIG. 6 is a graph showing a transition of a machining position accuracy parameter Δα during continuous machining of a conventional laser drill device on a rigid substrate and a laser drill device of the present invention.

FIG. 7 is a graph showing a transition of a machining position accuracy parameter Δα during continuous machining of a conventional laser drill device on a flexible substrate and the laser drill device of the present invention.

[Explanation of symbols]

1 Laser Oscillator 2 Ultraviolet Laser Light 3 Collimating Lens 4 Converged Ultraviolet Laser Light 5 Optical System Lens 6 Galvano XY Scan Mirror (X Axis) 7 Galvano XY Scan Mirror (Y Axis) 8 fθ Lens 9 Workpiece 10 Processing Table 11 Inspection Table 12 CCD Camera 13 Irradiation Laser Light 14 Irradiation Laser Light Distribution 15 Land 16 Irradiation Laser Light Distribution at Start of Laser Device 17 Irradiation Laser Light Distribution at Continuous Operation (No Position Correction Data) 18 Irradiation Laser at Continuous Operation Light distribution (with position correction data) 19 Conventional laser drill device 20 Laser drill device according to the present invention

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Claims (7)

[Claims] 1. A drill processing unit for forming a laser beam from a laser oscillator on a processing object to perform drilling on the processing object, and a processing position accuracy inspection unit.
A laser comprising: a means for transmitting correction data due to machining from the machining unit to the machining position accuracy inspection unit; and a means for transmitting correction data based on the inspection result from the machining position accuracy inspection unit to the machining unit. Drill equipment. 2. The processing unit and the processing position accuracy inspection unit in the laser drilling apparatus share the same CAD data, and the processing unit accuracy inspection unit processes the substrate shrinkage amount during processing from the processing unit to the processing position accuracy inspection unit. 2. The laser drilling device according to claim 1, further comprising means for transmitting to the unit an offset value of coordinates in which the amount of processing position deviation is corrected. 3. The processing position accuracy inspection unit transmits to the processing unit an offset value of coordinates in which the processing position deviation amount is corrected from the inspection result inspected by the processing head in outline during processing. The laser drill device according to 1 or 2. 4. A processing position accuracy inspection unit transmits to the processing unit an offset signal corrected by calculating a deviation amount from a target coordinate position in which the amount of shrinkage of the substrate is added, and the processing unit outputs the corrected offset signal based on the corrected offset signal. The laser drilling device according to claim 1, wherein the laser drilling unit is a drilling unit that performs drilling at a position where the target coordinate position is corrected. 5. The laser drilling device according to claim 1, wherein the output light from the laser oscillator is an ultraviolet laser light having a wavelength of a wavelength-converted third harmonic or more. 6. The laser drilling device according to claim 1, wherein laser light from a laser oscillator is imaged on an object to be processed consisting of upper and lower wiring layers sandwiching an insulating resin layer for drilling. At that time, a machining position accuracy inspection unit, means for transmitting correction data resulting from machining from the machining unit to the machining position accuracy inspection unit, and means for transmitting correction data based on the inspection result from the machining position accuracy inspection unit to the machining unit. The method for manufacturing a multilayer wiring board is characterized by performing a hole forming step for connecting upper and lower layers sandwiching an insulating resin layer by controlling a processing position. 7. A multilayer wiring board having holes formed by the hole forming step according to claim 6.