Manufacturing method of processed resin substrate and laser processing apparatus

A manufacturing method of a processed resin substrate includes: preparing a resin substrate including a resin layer and a metal layer that covers at least a part of one surface of the resin layer; and forming a through hole in the resin substrate by irradiating the resin substrate with pulsed laser light. In the forming of the through hole, an interval of irradiation of the pulsed laser light at each point on the resin substrate is 5 msec or more.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is entitled to and claims the benefit of Japanese Patent Application No. 2015-214787, filed on Oct. 30, 2015, the disclosure of which including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND

Technical Field

The present invention relates to a manufacturing method of a processed resin substrate and a laser processing apparatus.

Description of Related Art

In the field of printed substrates such as a glass epoxy substrate, resins such as epoxy resin and polyimide are often used as the insulating material. In a printed substrate having such a resin layer, a plurality of through holes are provided for various purposes. Conventionally, through holes have been formed by machine processing using drills, rooters, and the like. In recent years, through holes are formed by laser processing in some situation.

For example, Japanese Patent Application Laid-Open No. 2012-61480 discloses a method for forming a through hole by irradiating a flexible printed substrate including a polyimide resin layer having a thickness of 25 μm with pulsed laser light having a wavelength equal to or greater than 400 nm and smaller than 9 μm. In this method, a through hole is formed by performing scanning with pulsed laser light in multiple rounds along an annular path or a spiral path corresponding to a predetermined outer edge line of the through hole.

SUMMARY

According to one aspect of the present invention relates to a manufacturing method of a processed resin substrate including: preparing a resin substrate including a resin layer and a metal layer that covers at least a part of one surface of the resin layer; and forming a through hole in the resin substrate by irradiating the resin substrate with pulsed laser light. In the forming of the through hole, an interval of irradiation of the pulsed laser light at each point on the resin substrate is 5 msec or more.

Further, according to another aspect of the present invention relates to a laser processing apparatus that irradiates a resin substrate with pulsed laser light to form a through hole, the laser processing apparatus including: a laser light source that emits pulsed laser light; a stage on which to place a resin substrate including a resin layer and a metal layer that covers at least a part of one surface of the resin layer; an optical system that guides the pulsed laser light emitted from the laser light source to the resin substrate placed on the stage; a scanning section that moves at least one of the stage and a condensing point of the pulsed laser light guided by the optical system to relatively move the resin substrate placed on the stage and the condensing point of the pulsed laser light; and a control section that controls an operation of the scanning section. The control section controls the scanning section such that the pulsed laser light is applied in multiple rounds along a predetermined outer edge line of the through hole, and that an interval of irradiation at each point on the predetermined outer edge line between each round is 5 msec or more.

DESCRIPTION OF EMBODIMENT

1. Manufacturing Method of Processed Resin Substrate

A manufacturing method of a processed resin substrate according to the present embodiment is a method for obtaining a processed resin substrate by forming a through hole by laser processing in a resin substrate including a resin layer and a metal layer that covers at least a part of one surface of the resin layer. Here, the term “resin substrate” means a resin substrate before laser processing, and the term “processed resin substrate” means a resin substrate after laser processing. While the name of a resin substrate is different between before and after the laser processing, the physical property, the composition and the like of the resin substrate are not significantly different between before and after the laser processing.

In addition, “through hole” (broader concept) that is formed by the manufacturing method of a processed resin substrate according to the present embodiment includes a dotted “through hole” (narrower concept) which is formed without performing laser light scanning, and an “opening” which is formed by laser light scanning. Further, the “opening” includes “hole having a shape substantially identical to a scanning line” which is formed by scanning with laser light in a linear and/or a curved manner, and “hole having a shape substantially identical to a given region” which is formed by scanning with pulsed laser light enclosing the given region.

The manufacturing method of a processed resin substrate according to the present embodiment includes a first step of preparing a resin substrate, and a second step of forming a through hole by irradiating the resin substrate with pulsed laser light. The steps will be described below.

In the first step, as a processing object, a resin substrate including a resin layer and a metal layer that covers at least a part of one surface of the resin layer is prepared. The resin substrate may be prepared by buying a commercially available product, or by producing a resin substrate. The resin substrate is, but not limited to, a rigid printed circuit substrate, for example.

The type of the resin of the resin layer is not limited. Examples of the resin of the resin layer include epoxy resin, polyimide resin, polyethylene terephthalate resin, polyethylene naphthalate resin, bismaleimide triazine resin, phenol resin, silicone resin, modified silicone resin, epoxy modified silicone resin, polyphenylene ether resin, liquid crystal polymer resin and combinations thereof.

In addition, the resin layer may include a reinforcement for improving the strength, or may not include a reinforcement. Examples of the reinforcement include a glass fiber, ceramics, a ceramics fiber, paper, cloth, a carbon fiber, an aramid fiber and combinations thereof. Examples of the resin layer include a glass epoxy substrate and a polycarbonate substrate. The thickness of the resin layer is, but not limited to, 200 to 500 μm, for example.

The metal layer covers at least a part of one surface of the resin layer. To be more specific, the metal layer covers at least one surface of the resin layer of at least a part where the through hole is formed. The metal layer has a high thermal conductivity, and therefore has a function of effectively dissipating the excessive thermal energy accumulated in a region around the surface of the resin layer during the processing. In addition, the metal layer has a function of blocking transmission of oxygen into the resin layer from the outside. By the synergistic effect of the above-mentioned functions, the metal layer suppresses undesirable thermal damages such as burning and digging during the processing. In view of the foregoing, preferably, the metal layer covers the both surfaces of the resin layer, or more preferably, the metal layer covers the both surfaces of the resin layer in whole. In addition, one or more metal layers may be provided.

The type of the metal of the metal layer is not limited. Preferably, the metal of the metal layer has high thermal conductivity from the viewpoint of suppressing undesirable thermal damage in the second step. Examples of the metal of the metal layer include one or more metals selected from the group consisting of copper, silver, gold and aluminum, and alloys which contain the above-mentioned metals as the main component. The metal layer can be formed by sputtering, vapor deposition, plating and the like.

The thickness of the metal layer is, but not limited to, 2 to 50 μm, for example. The metal layer may be a thin layer such as a metal foil. As described above, the metal layer may cover the both surfaces of the resin layer, or two or more metal layers may be disposed on one surface of the resin layer. With such configurations, the thickness of each metal layer can be reduced. On the other hand, in the case where one metal layer is disposed on only one surface of the resin layer, it is necessary to increase the thickness of the metal layer to a certain degree from the viewpoint of suppressing thermal damage of the resin layer.

In addition, another metal layer intended for improvement of bonding force, prevention of migration and the like may be disposed between the resin layer and the metal layer for the heat transmission. Examples of such a metal layer include a Ni layer, a Cr layer, and a NiCr alloy layer having a thickness of about hundreds of nanometers, and the like.

In the second step, a portion of the resin substrate whose at least one surface is covered with the metal layer prepared in the first step is irradiated with pulsed laser light to form a through hole. For example, in the case where an opening is formed as a through hole (broader concept), the through hole (opening) is formed by repeating, in multiple rounds, the scanning with pulsed laser light along a predetermined outer edge line of the opening to be formed. At this time, preferably, the scanning with the pulsed laser light is performed in multiple rounds. In addition, preferably, the pulsed laser light is applied to the resin substrate from the side on which the metal layer is disposed from the viewpoint of suppressing thermal damage of the resin layer. In this case, the pulsed laser light is applied not only to the resin layer but also to the metal layer.

FIG. 1AtoFIG. 1Care schematic views of steps of forming opening140as a through hole in resin substrate110. In the example illustrated inFIG. 1AtoFIG. 1C, the both surfaces of resin layer110are covered with metal layer120.

As illustrated inFIG. 1A, while irradiating resin substrate100having resin layer110and metal layer120covering the both surfaces of resin layer110with pulsed laser light130, the relative position of the condensing point of pulsed laser light130and resin substrate100is changed. At this time, the condensing point of pulsed laser light130is located at an inner portion of resin layer110, and scanning with pulsed laser light130along predetermined outer edge line150′ of the opening140to be formed is performed in multiple rounds. By performing the scanning with pulsed laser light130in multiple rounds in the above-mentioned manner, groove160having a depth equal to the thickness of resin substrate100can be formed over the whole circumference of outer edge150of opening140as illustrated inFIG. 1B. Thereafter, as illustrated inFIG. 1C, opening140is formed by removing the portion separated by groove160. Through the above-mentioned procedure, opening140can be formed in resin substrate100. In this manner, a processed resin substrate can be manufactured.

It is to be noted that the shape of opening140is not limited to the shape illustrated inFIG. 1C. The cross-sectional shape of opening140in the direction along the substrate surface is not limited, and is, for example, a circular shape, an ellipse shape, a rectangular shape, or an elongated round shape. Alternatively, the cross-sectional shape of opening140in the direction along the substrate surface may be more complicated shapes. In addition, the scanning direction of pulsed laser light130is not limited to the clockwise direction illustrated inFIG. 1C, and may be the counterclockwise direction.

In addition, the position of the condensing point of pulsed laser light130is not limited to the position illustrated inFIG. 1A. For example, with the condensing point of pulsed laser light130, scanning may be performed on predetermined outer edge line150′, or performed inside predetermined outer edge line150′ in a direction substantially parallel to predetermined outer edge line150′. In addition, the position (depth) of the condensing point of pulsed laser light130in the thickness direction of resin substrate100may be constant regardless of the progress of the processing, or may be changed in accordance with the progress of the processing. For example, in the case where the thickness of resin substrate100is non-uniform, the position (depth) of the condensing point of pulsed laser light130may be changed in accordance with the thickness of resin substrate100.

In the laser processing method according to the present embodiment, scanning with pulsed laser light130is performed such that the interval of irradiation at each point on predetermined outer edge line150′ of opening140between each round is 5 msec or more. For example, scanning with pulsed laser light130is performed such that, at point A located on predetermined outer edge line150′ inFIG. 1A, the interval between irradiation with pulsed laser light130of nth-round and irradiation with pulsed laser light130of (n+1)th-round is 5 msec or more. In this manner, the excessive thermal energy accumulated in resin layer110can be effectively dissipated to metal layer120in a period between each round, and thermal damage at the processing portion of resin layer110can be suppressed.

The method for applying pulsed laser light130such that the interval of irradiation at each point on predetermined outer edge line150′ of opening140between each round is 5 msec or more is not limited, and may be appropriately selected in accordance with the shape, size, and number of opening140, and the like. For example, the above-mentioned condition can be satisfied by reducing the scanning speed of pulsed laser light130. In addition, even in the case where the scanning speed of pulsed laser light130is high (for example, 1000 mm/sec or more), the scanning time of one round of pulsed laser light130is 5 msec or more when opening140is large.

On the other hand, in the case where the scanning speed of pulsed laser light130is high (for example, 1000 mm/sec or more), and the size of opening140is small, the scanning time of one round of pulsed laser light130is less than 5 msec. In this case, it suffices to intermittently stop irradiation (scanning) with pulsed laser light130such that the interval of irradiation at each point on predetermined outer edge line150′ of opening140between each round is 5 msec or more. For example, in the case where the scanning time of one round of pulsed laser light130is 3 msec, it suffices to stop the scanning with pulsed laser light130for 2 msec or more in each round. The timing of stopping the irradiation with pulsed laser light130is not limited, and the irradiation may be stopped on a half-round basis, for example.

In addition, in the case where a plurality of openings140are formed in one resin substrate100, the irradiation region of pulsed laser light130(the region where opening140is to be formed) may be changed for each round. For example, when forming two openings, a first opening and a second opening, it suffices to perform irradiation such that, after pulsed laser light is applied along the predetermined outer edge line of the first opening in one round, pulsed laser light is applied along the predetermined outer edge line of the second opening in one round before performing the next irradiation along the predetermined outer edge line of the first opening. By alternately applying the pulsed laser light to the region where the first opening is to be formed and the region where the second opening is to be formed in the above-mentioned manner, the interval of irradiation at each point on predetermined outer edge line150′ of opening140between each round can be set to 5 msec or more without significantly reducing the processing efficiency.

The wavelength of pulsed laser light130is not limited as long as groove160can be appropriately formed in resin substrate100. From the viewpoint of suppressing undesirable thermal damage at the processing portion of resin layer110, the wavelength of pulsed laser light130is preferably 250 to 2000 nm, more preferably, 250 to 1500 nm. For example, the wavelength of pulsed laser light130is 355 nm.

The pulse energy of pulsed laser light130is not limited as long as groove160can be appropriately formed in resin substrate100. From the viewpoint of increasing the processing speed, the pulse energy of pulsed laser light130is preferably 3 μJ or greater.

The output of pulsed laser light130is not limited as long as groove160can be appropriately formed in resin substrate100. From the viewpoint of increasing the processing speed, the output of pulsed laser light130is preferably 10 W or greater.

The pulse width of pulsed laser light130is not limited as long as groove160can be appropriately formed in resin substrate100. From the viewpoint of improving the processing quality, the pulse width of pulsed laser light130is preferably 10 psec to 100 nsec.

The repetition frequency of pulsed laser light130is not limited as long as groove160can be appropriately formed in resin substrate100. From the viewpoint of improving the processing quality, the repetition frequency of pulsed laser light130is preferably 100 kHz or greater, or more preferably 1 MHz or greater.

The pulse energy and the fluence of pulsed laser light130is not limited as long as groove160can be appropriately formed in resin substrate100. For example, in the case where the wavelength of pulsed laser light130is 355 nm, the pulse energy of pulsed laser light130is preferably 3 μJ or greater from the viewpoint of increasing the processing speed. Likewise, in the case where the wavelength of pulsed laser light130is 355 nm, the fluence of pulsed laser light130on the surface of resin substrate100(the surface of metal layer110on which pulsed laser light130is applied) is preferably 3 J/cm2or greater, and the fluence of pulsed laser light130at the condensing point is preferably 10 J/cm2or greater from the viewpoint of increasing the processing speed. Here, “the surface of resin substrate100” means the surface of metal layer120in the case where pulsed laser light130is applied to the surface where metal layer120is formed in the surface of resin layer110, or is the surface of resin layer110in the case where pulsed laser light130is applied to the surface where metal layer120is not formed in the surface of resin layer110.

While the scanning speed of pulsed laser light130is not limited, the scanning speed of pulsed laser light130is preferably 1000 mm/sec or more from the viewpoint of increasing the processing speed. In addition, the number of cycles of scanning with pulsed laser light130for each opening140is not limited as long as groove160having a depth equal to the thickness of resin substrate100can be formed, and may be appropriately set in accordance with the material of resin substrate100, the output of pulsed laser light130and the like.

As described above, in the manufacturing method of a processed resin substrate according to the present embodiment, at least a part of one surface of the resin layer is covered with the metal layer, and the interval of irradiation of the pulsed laser light at each point on the resin substrate is set to 5 msec or more. In this manner, the manufacturing method of a processed resin substrate according to the present embodiment can form a through hole in the resin substrate (the resin layer) while suppressing undesirable thermal damages such as burning and digging even when laser light having a high output (for example, 10 W or greater) is applied at a high scanning speed (for example, 1000 mm/sec or more). Accordingly, the manufacturing method of a processed resin substrate according to the present embodiment can speedily form a through hole in a resin substrate without reducing the processing quality. In addition, even when a reinforcement such as a glass fiber is present in the resin layer, the manufacturing method of a processed resin substrate according to the present embodiment can form a through hole in the resin substrate without melting the reinforcement.

The way of implementing the manufacturing method of a processed resin substrate according to the present embodiment is not limited. For example, the manufacturing method of a processed resin substrate according to the present embodiment can be implemented with the laser processing apparatus according to the present embodiment described below.

2. Laser Processing Apparatus

The laser processing apparatus according to the present embodiment is used in the second step of the laser processing method according to the present embodiment. That is, the laser processing apparatus according to the present embodiment is an apparatus that irradiates a resin substrate including a resin layer and a metal layer that covers at least a part of one surface of the resin layer with pulsed laser light to form a through hole.

The laser processing apparatus according to the present embodiment includes, at least, a laser light source that emits pulsed laser light, a stage, an optical system that guides pulsed laser light emitted from the laser light source to a resin substrate placed on the stage, a scanning section that relatively moves the resin substrate placed on the stage and the condensing point of the pulsed laser light, and a control section that controls the operation of the scanning section. Each component is described below.

The laser light source emits pulsed laser light for irradiating the resin substrate. The type of the laser used as the laser light source is not limited, and is appropriately selected in accordance with the type of the resin substrate and the like. Examples of the laser include a fiber laser and the like.

On the stage, a processing object, that is, a resin substrate including a resin layer, and a metal layer that covers at least a part of one surface of the resin layer is placed.

The optical system guides pulsed laser light emitted from the laser light source to the resin substrate placed on the stage such that the condensing point is located at a desired position. Normally, the optical system includes a telescope optical system that optimizes the beam diameter of pulsed laser light, a condenser lens that condenses pulsed laser light at a desired position, and the like.

The scanning section moves at least one of the stage and the condensing point of the pulsed laser light to relatively move the resin substrate placed on the stage and the condensing point of the pulsed laser light. In this manner, it is possible to form a through hole (opening) in the resin substrate by performing scanning such that the condensing point of the pulsed laser light is applied along a predetermined outer edge line of the through hole (opening) to be formed. The scanning section may move the stage on which the resin substrate is placed, or the condensing point of the pulsed laser light, or both. The driving section is, for example, an XY-stage controller, a galvano scanner, or the like.

The control section controls the scanning section such that pulsed laser light is applied along the predetermined outer edge line of the through hole (opening) to be formed in multiple rounds, and the interval of irradiation at each point on the predetermined outer edge line between each round is 5 msec or more. The control section is, for example, a computer connected with the scanning section.

Further, the laser processing apparatus may include an automatic aiming system for setting the position of the condensing point of the pulsed laser light at a desired position in a resin substrate and the like.

FIG. 2is a schematic view illustrating a laser processing apparatus according to the embodiment of the present invention. As illustrated inFIG. 2, laser processing apparatus200includes laser light source210, telescope optical system220, galvano scanner230, fθ lens240, stage250, AF camera260, XY-stage controller270, Z-controller280and computer290. In this example, resin substrate100as a processing object includes resin layer110, and metal layer120that covers the both surfaces of resin layer110.

Laser light source210emits pulsed laser light130having a given wavelength. As described above, the type of the laser used as laser light source210is appropriately selected in accordance with the type of resin substrate110as the processing object and the like.

Telescope optical system220optimizes the beam diameter of pulsed laser light130emitted from laser light source210to obtain a preferable processing shape.

In response to a request from computer290, galvano scanner230changes the travelling direction of pulsed laser light130optimized by telescope optical system220. Pulsed laser light130whose travelling direction is controlled by galvano scanner230is condensed in resin substrate100by fθ lens240. With such a combination of galvano scanner230and fθ lens240, scanning with the condensing point of pulsed laser light130can be performed along predetermined outer edge line150′ of the opening140to be formed at a constant speed.

Stage250includes a mounting stand on which resin substrate100is placed, and a driving mechanism that can move the mounting stand. The driving mechanism can move the mounting stand in the X-axis direction or the Y-axis direction, and can rotate the mounting stand around the X axis or the Y axis. Resin substrate100on stage250is moved in the XY-axis direction by the driving mechanism.

AF camera260is a camera for acquiring the profile of the surface of a processing portion of resin substrate100. The acquired profile is output to computer290.

In response to a request from computer290, XY-stage controller270moves stage250in the XY-axis direction such that the condensing point of pulsed laser light130is located at the region where opening140is to be formed in resin substrate100.

In response to a request from computer290, Z-controller280moves fθ lens240in the Z-axis direction such that the condensing point of pulsed laser light130is located in the resin layer120.

Computer290is connected with laser light source210, galvano scanner230, AF camera260, XY-stage controller270and Z-controller280, and comprehensively controls the connected components. For example, computer280controls AF camera260and XY-stage controller270to acquire the profile of the surface of resin substrate100. In addition, computer290controls galvano scanner230and Z-controller270to perform scanning with pulsed laser light130in multiple rounds along predetermined outer edge line150′ of opening140. In addition, computer280controls XY-stage controller260to move stage250such that the region where opening140is to be formed can be irradiated with pulsed laser light130.

Next, procedure of forming opening140as a through hole in resin substrate100with use of laser processing apparatus200is described.

First, resin substrate100is placed on the mounting stand of stage250, and the profile of the surface of resin substrate100is acquired with AF camera260and XY-stage controller270.

Next, resin substrate100is moved to a given position with XY-stage controller270, and thereafter pulsed laser light130is emitted from laser light source210to irradiate resin substrate100with pulsed laser light130. At this time, the travelling direction of pulsed laser light130is changed with galvano scanner230to thereby perform scanning with pulsed laser light130in multiple rounds along predetermined outer edge line150′ of opening140to be formed (seeFIG. 1A). In addition, the scanning with pulsed laser light130is performed such that the interval of irradiation at each point on predetermined outer edge line150′ of opening140between each round is 5 msec or more. For example, the scanning with pulsed laser light130is stopped for a given time in each round such that the interval of irradiation at each point on predetermined outer edge line150′ of opening140between each round is 5 msec or more. By applying pulsed laser light130in this manner, groove160that reaches the rear surface of resin substrate100can be formed along predetermined outer edge line150′ of opening140while suppressing undesirable thermal damages such as burning and digging (seeFIG. 1B). In the case where a plurality of openings140are formed in resin substrate100, it suffices to repeat the above-mentioned steps after moving resin substrate100with XY-stage controller270.

Finally, the portion separated by groove160is removed, and thus opening140is formed (seeFIG. 1C).

Through the above-mentioned procedure, a through hole can be formed in resin substrate100while suppressing undesirable thermal damages such as burning and digging.

WhileFIG. 2illustrates an example case where the travelling direction of pulsed laser light130is changed with galvano scanner230to apply pulsed laser light130along predetermined outer edge line150′ of opening140, the way of applying pulsed laser light130along predetermined outer edge line150′ of opening140is not limited as long as the condensing point of pulsed laser light130and resin substrate100can be relatively moved. For example, stage250or the optical system (telescope optical system220and the condenser lens) may be moved without using galvano scanner230.

EXAMPLES

The present invention will be described in detail with Examples. The present invention is not limited to Examples.

As a processing object, a glass epoxy substrate (thickness: 300 to 330 μm) on which a copper layer (thickness: 2 to 5 μm) is bonded on the both sides thereof was prepared.

With use of the laser processing apparatus illustrated inFIG. 2, the glass epoxy substrate was irradiated with pulsed laser light along the predetermined outer edge line of the opening to form an opening having an elongated round shape (the length of the straight line portion: 2 mm, the diameter of the arc portion: 0.55 mm). The scanning time of one round of the predetermined outer edge line of the opening was 2.9 msec. In addition, in each round of the scanning with the pulsed laser light, irradiation (scanning) with the pulsed laser light was stopped for a given time (0 to 150 msec) to change the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening. The interval of the irradiation between each round at each point on the predetermined outer edge line of the opening is calculated by “2.9 msec (scanning time of one round)+0 to 150 msec (scanning stop time).”

The condition of the processing was as follows. The “spot diameter” means the diameter of the range up to the light intensity of 1/e2with respect to the center portion (the same applies to the following Examples).

Position of condensing point: 100 μm from the surface of the copper layer on the front side

Spot diameter of the surface of the copper layer on the front side: 10.5 μm

Fluence of the surface of the copper layer on the front side: 18 J/cm2

Spot diameter at the condensing point: 5.6 μm

FIG. 3AtoFIG. 3Fare photographs (plan views) of substrates after pulsed laser light is applied along the predetermined outer edge line of the opening in 60 cycles (seeFIG. 1B).FIG. 3Ais a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 0 msec (continuous scan).FIG. 3Bis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 10 msec.FIG. 3Cis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 20 msec.FIG. 3Dis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 50 msec.FIG. 3Eis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 100 msec.FIG. 3Fis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 150 msec.

As illustrated inFIG. 3A, in the case where the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening was 2.9 msec (in the case where the scanning stop time was 0 msec), burning occurred in a region around the processing portion. On the other hand, as illustrate inFIG. 3BtoFIG. 3F, in the case where the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening was 12.9 msec or more (in the case where the scanning stop time was 10 to 150 msec), almost no burning occurred in a region around the processing portion. From the above-mentioned results, it can be said that undesirable thermal damages such as burning can be suppressed by setting the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening to 5 msec or more.

As a processing object, a glass epoxy substrate (thickness: 300 to 330 μm) on which a copper layer (thickness: 2 to 5 μm) is bonded on the both sides thereof was prepared.

With use of the laser processing apparatus illustrated inFIG. 2, the glass epoxy substrate was irradiated with pulsed laser light along the predetermined outer edge line of the opening to form an opening having a circular shape (having a diameter of 1 mm). The scanning time of one round of the predetermined outer edge line of the opening was 0.8 msec. In addition, in each round of the scanning with the pulsed laser light, irradiation (scanning) with the pulsed laser light was stopped for a given time (0 to 100 msec) to change the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening. The interval of the irradiation between each round at each point on the predetermined outer edge line of the opening is calculated by “0.8 msec (scanning time of one round)+0 to 100 msec (scanning stop time).”

The condition of the processing was as follows.

Position of condensing point: 100 μm from the surface of the copper layer on the front side

Spot diameter of the surface of the copper layer on the front side: 10.5 μm

Fluence of the surface of the copper layer on the front side: 18 J/cm2

Spot diameter at the condensing point: 5.6 μm

FIG. 4AtoFIG. 4Qare photographs (plan views) of substrates after pulsed laser light is applied along the predetermined outer edge line of the opening in 60 cycles (seeFIG. 1B).FIG. 4Ais a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 0 msec (continuous scan).FIG. 4Bis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 1 msec.FIG. 4Cis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 2 msec.FIG. 4Dis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 3 msec.FIG. 4Eis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 4 msec.FIG. 4Fis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 5 msec.FIG. 4Gis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 6 msec.FIG. 4His a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 7 msec.FIG. 4Iis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 8 msec.FIG. 4Jis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 9 msec.FIG. 4Kis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 10 msec.FIG. 4Lis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 15 msec.FIG. 4Mis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 20 msec.FIG. 4Nis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 25 msec.FIG. 4Ois a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 30 msec.FIG. 4Pis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 50 msec.FIG. 4Qis a photograph of a substrate irradiated with pulsed laser light with a scanning stop time of 100 msec.

As illustrated inFIG. 4AtoFIG. 4E, in the case where the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening was 0.8 to 4.8 msec (in the case where the scanning stop time was 0 to 4 msec), burning occurred in a region around the processing portion. On the other hand, as illustrated inFIG. 4FtoFIG. 4Q, in the case where the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening was 5.8 msec or more (in the case where the scanning stop time was 5 to 100 msec), almost no burning occurred in a region around the processing portion. From the above-mentioned results, it can be said that undesirable thermal damages such as burning can be suppressed by setting the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening to 5 msec or more.

As a processing object, a glass epoxy substrate (thickness: 300 to 330 μm) on which a copper layer (thickness: 2 to 5 μm) is bonded on the both sides thereof was prepared.

With use of the laser processing apparatus illustrated inFIG. 2, the glass epoxy substrate was irradiated with pulsed laser light along the predetermined outer edge line of the opening to form openings of two types (the length of the straight line portion: 2 mm or 14.6 mm, the diameter of the arc portion: 0.55 mm) having an elongated round shape which differ from each other in length of the straight line portion. The scanning time of one round of the predetermined outer edge line of the opening whose length of the straight line portion is 2 mm was 2.9 msec. The scanning time of one round of the predetermined outer edge line of the opening whose length of the straight line portion is 14.6 mm was 15.5 msec. In addition, in each round of the scanning with the pulsed laser light, irradiation (scanning) with the pulsed laser light was stopped for a given time (0 to 100 msec) to change the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening. The interval of the irradiation between each round at each point on the predetermined outer edge line of the opening whose length of the straight line portion is 2 mm is calculated by “2.9 msec (scanning time of one round)+0 to 100 msec (scanning stop time).” Likewise, the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening whose length of the straight line portion is 14.6 mm is calculated by “15.5 msec (scanning time of one round)+0 to 100 msec (scanning stop time).”

The condition of the processing was as follows.

Position of condensing point: 100 μm from the surface of the copper layer on the front side

Spot diameter of the surface of the copper layer on the front side: 10.5 μm

Fluence of the surface of the copper layer on the front side: 18 J/cm2

Spot diameter at the condensing point: 5.6 μm

FIG. 5AandFIG. 5Bare photographs (plan views) of substrates after pulsed laser light is applied along the predetermined outer edge line of the opening in 60 cycles (seeFIG. 1B).FIG. 5Ais a photograph of a substrate after pulsed laser light was applied to form an opening whose length of the straight line portion is 2 mm, andFIG. 5Bis a photograph of a substrate after pulsed laser light was applied to form an opening whose length of the straight line portion is 14.6 mm. In the two substrates, seven openings were formed for each scanning stop time. For example, the seven irradiation regions of the upper right portion enclosed with the broken line were irradiated with pulsed laser light with a scanning stop time of 0 msec (continuous scan), and the seven irradiation regions of the lower left portion enclosed with the broken line were irradiated with pulsed laser light with a scanning stop time of 100 msec.

As illustrated inFIG. 5A, in the case where the scanning time of one round of the predetermined outer edge line of the opening was 2.9 msec, burning occurred in a region around the processing portion when the interval of the irradiation between each round at each point was 2.9 to 4.9 msec (when the scanning stop time was 0 to 2 msec), whereas almost no burning occurred in a region around the processing portion when the interval of the irradiation between each round at each point was 5.9 to 102.9 msec (when the scanning stop time was 3 to 100 msec). On the other hand, as illustrated inFIG. 5B, in the case where the scanning time of one round of the predetermined outer edge line of the opening was 15.5 msec, almost no burning occurred in a region around the processing portion regardless of the scanning stop time. From the above-mentioned results, it can be said that undesirable thermal damages such as burning can be suppressed by setting the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening to 5 msec or more. In addition, it can be said that the scanning with pulsed laser light is not required to be stopped in the case where the scanning time of one round of the predetermined outer edge line of the opening is 5 msec or more.

FIG. 6AtoFIG. 6Hare photographs (cross sections) of openings after formation of the openings (seeFIG. 1C).FIG. 6AtoFIG. 6Care photographs of the processed cross sections of openings whose length of the straight line portion is 2 mm, andFIG. 6DtoFIG. 6Hare photographs of processed cross sections of openings whose length of the straight line portion is 14.6 mm.FIG. 6AandFIG. 6Dillustrate openings formed with a scanning stop time of 0 msec (continuous scan).FIG. 6Eillustrates an opening formed with a scanning stop time of 10 msec.FIG. 6Fillustrates an opening formed with a scanning stop time of 20 msec.FIG. 6BandFIG. 6Gillustrate openings formed with a scanning stop time of 50 msec.FIG. 6CandFIG. 6Hillustrate openings formed with a scanning stop time of 100 msec.

As illustrated inFIG. 6AtoFIG. 6C, in the case where the scanning time of one round of the predetermined outer edge line of the opening was 2.9 msec, the glass fiber was melted at the processed portion when the interval of the irradiation between each round at each point is 2.9 msec (when the scanning stop time was 0 msec), whereas almost no glass fiber was melted when the interval of the irradiation between each round at each point is 12.9 to 102.9 msec (when the scanning stop time was 10 to 100 msec). On the other hand, as illustrated inFIG. 6DtoFIG. 6H, in the case where the scanning time of one round of the predetermined outer edge line of the opening was 15.5 msec, the almost no glass fiber was melted regardless of scanning stop time. From the above-mentioned results, it can be said that reduction in processing quality such as melting of the glass fiber can be suppressed by setting the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening to 5 msec or more. In addition, it can be said that the scanning with pulsed laser light is not required to be stopped in the case where the scanning time of one round of the predetermined outer edge line of the opening is 5 msec or more.

As a processing object, a glass epoxy substrate (thickness: 300 to 330 μm) on which a copper layer (thickness: 2 to 5 μm) is bonded on the both sides thereof was prepared.

With use of the laser processing apparatus illustrated inFIG. 2, the glass epoxy substrate was irradiated with pulsed laser light along the predetermined outer edge line of the opening to form an opening (diameter 0.4 mm) having a circular shape. The scanning time of one round of the predetermined outer edge line of the opening was 2.1 msec. At this time, the pulse energy was changed (8.3 to 50.3 μJ. In addition, in each round of the scanning with the pulsed laser light, irradiation (scanning) with the pulsed laser light was stopped for 100 msec (continuous irradiation was also performed for comparison purpose). The interval of the irradiation between each round at each point on the predetermined outer edge line of the opening is calculated by “2.1 msec (scanning time of one round)+100 msec (scanning stop time).”

The condition of the processing was as follows.

Position of condensing point: 100 μm from the surface of the copper layer on the front side

Spot diameter of the surface of the copper layer on the front side: 10.5 μm

Fluence of the surface of the copper layer on the front side: 10.0 to 60.0 J/cm2

Spot diameter at the condensing point: 5.6 μm

Fluence at the condensing point: 33.7 to 204 J/cm2

FIG. 7AtoFIG. 7Hare photographs (plan views) of substrates after pulsed laser light was applied along the predetermined outer edge line of the opening in 10 cycles (seeFIG. 1B).FIG. 7AtoFIG. 7Dare photographs of substrates irradiated with pulsed laser light with a scanning stop time of 0 msec (continuous scan), andFIG. 7EtoFIG. 7Hare photographs of substrates irradiated with pulsed laser light with a scanning stop time of 100 msec.FIG. 7AandFIG. 7Eare photographs of substrates irradiated with pulsed laser light having a pulse energy of 8.3 μJ (surface fluence: 10.0 J/cm2, internal condense light fluence: 33.7 J/cm2).FIG. 7BandFIG. 7Fare photographs of substrates irradiated with pulsed laser light having a pulse energy of 10.6 μJ (surface fluence: 12.7 J/cm2, internal condense light fluence: 43.1 J/cm2).FIG. 7CandFIG. 7Gare photographs of substrates irradiated with pulsed laser light having a pulse energy of 13.8 μJ (surface fluence: 16.6 J/cm2, internal condense light fluence: 56.1 J/cm2).FIG. 7DandFIG. 7Hare photographs of substrates irradiated with pulsed laser light having a pulse energy of 50.3 μJ (surface fluence: 60.0 J/cm2, internal condense light fluence: 204 J/cm2). It is to be noted that, inFIG. 7DandFIG. 7H, portions separated by irradiation with laser are dropped off.

As illustrated inFIG. 7AtoFIG. 7D, in the case where the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening was 2.1 msec (in the case where the scanning stop time was 0 msec), burning occurred in a region around the processing portion regardless of the pulse energy. On the other hand, as illustrated inFIG. 7EtoFIG. 7H, in the case where the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening was 102.1 msec (in the case where the scanning stop time was 100 msec), almost no burning occurred in a region around the processing portion regardless of the pulse energy. From the above-mentioned results, it can be said that undesirable thermal damages such as burning can be suppressed, regardless of the pulse energy, by setting the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening to 5 msec or more.

As a processing object, a glass epoxy substrate (having a thickness, including the copper layer, of 200 μm) on which a copper layer (thickness: 2 to 5 μm) is bonded on the both sides thereof was prepared.

With use of the laser processing apparatus illustrated inFIG. 2, the glass epoxy substrate was irradiated with pulsed laser light along the predetermined outer edge line of the opening to form an opening having an elongated round shape (the length of the straight line portion: 5.5 mm, the diameter of the arc portion: 0.5 mm). The scanning time of one round of the predetermined outer edge line of the opening was 63 msec. In addition, in each round of the scanning with the pulsed laser light, irradiation (scanning) with the pulsed laser light was stopped for 184 msec. The interval of the irradiation between each round at each point on the predetermined outer edge line of the opening is calculated by “63 msec (scanning time of one round)+184 msec (scanning stop time).”

The condition of the processing was as follows.

Position of condensing point: 70 μm from the surface of the copper layer on the front side

Spot diameter of the surface of the copper layer on the front side: 9.9 μm

Fluence of the surface of the copper layer on the front side: 78 J/cm2

Spot diameter at the condensing point: 5 μm

FIG. 8is a photograph (plan view) of a substrate after pulsed laser light was applied (seeFIG. 1B) along the predetermined outer edge line of the opening in 30 cycles. At a center portion of the irradiation region, a portion separated by irradiation with laser is dropped off. As illustrated inFIG. 8, in the case where the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening was 247 msec, almost no burning occurred in a region around the processing portion. From the above-mentioned results, it can be said that undesirable thermal damages such as burning can be suppressed by setting the interval of the irradiation between each round at each point on the predetermined outer edge line of the opening to 5 msec or more, even in the case where pulsed laser light having a wavelength of 1064 nm is used.

The manufacturing method of a processed resin substrate according to the embodiment of the present invention can speedily form a through hole in a resin substrate without reducing the processing quality. For example, with the manufacturing method of a processed resin substrate according to the embodiment of the present invention, speedup of the manufacturing process of a semiconductor device can be achieved.