JP5162977B2 - Laser drilling method - Google Patents

Description

  The present invention relates to a laser drilling method, and more particularly to a laser drilling method in a manufacturing process of a printed wiring board.

As a conventional printed wiring board manufacturing method, a resin sheet made of an insulating resin material is sandwiched between copper foils and heat molded, then holes are formed in the resin sheet and copper foil, and the formed holes are filled with a conductive paste. What to do is known. In the hole forming process, for example, as shown in Patent Document 1, a hole forming portion (corresponding to a hole to be drilled) of the copper foil is removed by etching, and laser light having a diameter larger than that of the mask opening is obtained using this copper foil as a mask. There are cases where so-called conformal drilling, in which a resin sheet is punched by irradiation, is performed. Moreover, as disclosed in, for example, Patent Document 2, a so-called direct drilling may be performed in which a copper foil that has not been etched is irradiated with laser light focused to a desired diameter, and the copper foil and the resin sheet are simultaneously drilled. is there. In addition, it is also known that a resin sheet is heat-molded and then a hole is formed in the resin sheet by laser light irradiation or a drill, and then copper plating is applied to the resin sheet.
JP-A-8-279679 JP 2001-135911 A

  In any of the methods described above, a hole is made in the cured resin sheet after heat molding. On the other hand, in recent years, a method is used in which a resin sheet before heat molding is irradiated with a laser beam to perform drilling, and then the formed holes are filled with a conductive paste and sandwiched by copper foil or the like and heat molded. It is coming. In this method, it is general to sequentially irradiate laser beams in accordance with the arrangement order of the hole forming portions of the resin sheet. FIG. 10 (a) is a perspective view showing a resin sheet before heat molding subjected to drilling by this method, and FIG. 10 (b) is a diagram of the resin sheet before heat molding shown in FIG. 10 (a). It is XX sectional drawing.

  As the resin sheet 20 shown in FIG. 10, what is called a prepreg in which a resin material such as a monomer, a filler such as an aluminum material, a glass cloth, an aramid nonwoven fabric, or the like is combined is used. When such a resin sheet 20 is drilled by irradiating a pulse type carbon dioxide laser, for example, the resin, the filler, and the glass cloth are removed by the heat of the far-infrared laser beam having a wavelength of about 9.4 μm. Will do. At this time, the central temperature of the laser beam is very high at 2000 ° C. or higher. Since the resin sheet 20 has low heat resistance and softens or melts around 100 ° C., the through holes 40 are continuously formed at a narrow pitch (for example, a pitch of about 0.3 mm or less) as shown in FIG. Then, as shown in FIG. 10B, the resin sheet 20 may wave due to the accumulation of heat. Further, the resin contained in the resin sheet 20 may melt and close the adjacent through hole 40. Note that the pitch at which undulation deformation begins to occur in the resin sheet 20 before heat molding may vary from approximately 0.4 mm to 0.2 mm depending on the degree of denseness of the hole forming portions. When the inventor observed the undulated deformation portion with a microscope, there was evidence that the resin was heated to a temperature exceeding 100 ° C., such as generation of bubbles between the through holes 40 in a portion where the through holes 40 were dense. It was seen.

  Thus, in the state where the resin sheet 20 is undulated, a uniform gap is formed between the table / sheet-like material / squeegee of the paste printing machine when the conductive paste is filled into the through holes 40. It becomes difficult to fill the conductive paste. As a result, there is a possibility of causing a conduction failure and a possibility that the wave remains deformed even after heat molding with a copper foil or the like, which may result in a defective printed wiring board. In place of the carbon dioxide laser, an ultraviolet YAG (UV-YAG) laser using a third or fourth harmonic of a YAG laser may be used for manufacturing a printed wiring board. Therefore, high heat is generated during photochemical decomposition (ablation processing) of the resin. Therefore, the processing is substantially performed by ultraviolet rays and heat, and the same problem as in the case of using a carbon dioxide laser occurs.

  In recent years, semiconductor packages mounted on printed wiring boards have been downsized. For example, in a package called CSP, the pitch of connection bumps may be less than 0.3 mm. In addition, with the miniaturization of semiconductor packages, there is an increasing need for wiring boards capable of high density connection. However, in the conventional method, as described above, when the hole forming portions are dense, undulation deformation or the like is likely to occur, and thus it is difficult to manufacture a wiring board capable of high-density connection.

  Therefore, an object of the present invention is to provide a laser drilling method capable of suppressing the occurrence of undulation deformation and the like even when drilling a sheet-like member having low heat resistance at a narrow pitch.

  In order to achieve such an object, the present inventor has conducted various studies.

  When a hole is made after hot-molding a resin sheet sandwiched between copper foils, a cycle processing method that takes about 1.5 times as long may be used instead of a high-speed burst processing method. In the burst processing method, several shots of pulsed laser light are continuously irradiated to a hole forming portion, a hole is formed at the hole forming portion, and then a pulse laser beam is irradiated to the next planned drilling portion. In this method, heat is likely to be accumulated in the copper foil on the bottom side of the hole, and if the thickness of the copper foil on the bottom side of the hole is thin, the copper foil may be damaged. On the other hand, in the cycle processing method, the process of irradiating the laser beam one shot at a time to all the holes to be drilled is repeated a plurality of times. With this method, there is little accumulation of heat at the planned drilling location, and damage to the copper foil on the bottom side of the hole can be suppressed.

  Based on the facts described above, the present inventor can initially suppress the occurrence of undulating deformation, etc., even when drilling at a narrow pitch in a resin sheet before heat molding by applying a cycle processing method instead of a burst processing method. I thought that. Therefore, a resin sheet before heat molding in which holes are formed in various patterns was prepared, and drilling was attempted by a burst processing method and a cycle processing method. As a result, when the density of the hole forming portion (hereinafter referred to as the hole density) was low, the drilling process could be performed sufficiently satisfactorily by the burst processing method. However, when the hole density is increased, more specifically, when the pitch of the hole forming portion is, for example, 0.05 to 0.3 mm, it is difficult to perform the drilling process favorably by the burst processing method, and the cycle processing method is used. Otherwise, the resin sheet wavy. Further, it was found that the resin sheet wavy in a certain pattern even when the cycle processing method was used. A certain pattern is, for example, a portion having a size of about 5 mm × 5 mm in a low hole density area and a narrow pitch of hole formation portions of about 0.2 mm, that is, a portion having a high hole density. Is a pattern that is unevenly distributed, and such a pattern is assumed for a substrate on which a small and high-density package such as a CSP is mounted.

  In general, a laser beam machine for a printed wiring board operates with a combination of a wide movement of about 500 mm by an XY table and a narrow movement of 30 mm to 50 mm by a galvano scanner. In the cycle processing method, for example, irradiation of one shot is repeated several times within a galvano scan range of 30 mm × 30 mm. Within this galvano scan range, if a plurality of portions having a size of about 5 mm × 5 mm and extremely narrow pitches of the locations to be drilled are unevenly distributed, laser light that becomes 2000 ° C. or more in one shot is irradiated for a short time. Irradiate a very narrow range several times. As a result, the present inventors speculated that heat is accumulated in the resin sheet, and the phenomenon that the material undulates occurs despite the use of the cycle processing method.

  From the above, the present inventor has completed the following invention.

  That is, the laser drilling method of the present invention is a laser drilling method in which drilling is performed by sequentially irradiating a plurality of scheduled drilling locations of a sheet-like member with laser light, and at least a part of the scheduled drilling locations. , After irradiating one scheduled drilling point with laser light, skip the scheduled drilling point located within the predetermined range from the one scheduled drilling point, and plan the drilling location located outside the predetermined range Is characterized by irradiating with laser light.

  In the laser drilling method of the present invention, when a laser beam is irradiated to a predetermined drilling location, the planned drilling location located in the vicinity is skipped and the laser beam is irradiated to the planned drilling location located at a distance. Therefore, it is possible to avoid a situation in which laser light is irradiated to a region having heat by laser light irradiation, and heat accumulation can be suppressed. Therefore, even when punching a sheet-like member with low heat resistance at a narrow pitch, it is difficult for the sheet-like member to corrugate or to melt and close the adjacent hole.

  In addition, the laser drilling method of the present invention includes a preparation step for determining the order of the planned drilling locations, and an irradiation step for irradiating the planned drilling locations with laser light according to the order of the planned drilling locations. The preparation step includes a dividing step of dividing the sheet-like member into a plurality of divided regions, a first order determining step for determining the order of the divided regions divided in the dividing step, and a first order determining step. A second order determination step of determining the order of the planned drilling locations according to the determined order of the segmented regions, wherein at least some of the plurality of segmented regions include the planned drilling locations, In the order determination step, it is preferable that the order of the divided areas is not continuous between adjacent divided areas.

  In this case, it is possible to more reliably suppress heat from being accumulated in the sheet-like member because it is suppressed to continuously irradiate the adjacent divided regions with the laser beam.

  Further, in the laser drilling method of the present invention, the dividing step divides the sheet-like member into a plurality of divided areas and divides the plurality of divided areas into a plurality of groups so that adjacent divided areas belong to the same group. The first order determining step classifies the first step of determining the priority order in the group for the divided regions, and the second step of determining the order of the divided regions according to the priority order determined in the first step. In the second step, it is preferable that the divided regions have the same priority order and the divided regions in different groups belong to each other.

  In this case, after irradiating a part of divided regions belonging to a certain group with laser light, it is possible to irradiate a part of divided regions belonging to another group with laser light. Since each group is composed of adjacent divided regions, there is a high possibility that divided regions having different groups belong to each other with a sufficient interval. Therefore, since it is suppressed to continuously irradiate the divided regions located in the vicinity, it is possible to suppress the occurrence of wavy deformation or the like in the sheet-like member.

  In the laser drilling method of the present invention, it is preferable that the plurality of divided regions are regions formed by dividing the sheet-like member into rows. The plurality of divided regions are preferably regions formed by dividing the sheet-like member into a lattice shape. In this case, since the divided areas are regularly arranged, it is possible to easily grasp the positional relationship of the divided areas.

  Further, the laser drilling method of the present invention further includes a detection step of detecting the distribution status of the planned drilling locations in the sheet-like member, and in the dividing step, based on the distribution status of the planned drilling locations detected in the detection step, It is preferable to divide a part of the sheet-like member into a plurality of divided regions. In this case, for example, it is possible to perform the drilling process in the above-described procedure only for an area where the planned drilling locations are dense.

  Moreover, in the laser drilling method of this invention, it is preferable that a sheet-like member consists of a mixture containing resin. In the laser drilling method of the present invention, the laser beam is preferably a pulsed carbon dioxide laser or an ultraviolet YAG laser. In this case, the wavy deformation of the sheet-like member can be more reliably suppressed.

  According to the present invention, it is possible to provide a laser drilling method capable of suppressing the occurrence of undulating deformation or the like even when drilling a sheet-like member having low heat resistance at a narrow pitch.

  Hereinafter, a preferred embodiment of a laser drilling method according to the present invention will be described with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified.

(First embodiment)
FIG. 1 is a perspective view showing a sheet punched by the laser drilling method according to the first embodiment. FIG. 2 is a diagram for explaining the laser drilling method according to the first embodiment.

  In the laser drilling method according to the present embodiment, a through hole 4 (hole) is formed by irradiating a laser beam to a predetermined drilling spot 14 in a sheet (sheet-like member) 2. In the present embodiment, the sheet 2 is a sheet made of a mixture containing a resin. The scheduled holes 14 are arranged at a predetermined arrangement pitch D in 6 rows and 6 columns.

  In the laser drilling method according to the present embodiment, a part of the 36 planned drilling locations 14 is irradiated with laser light to one planned drilling location 14 and then a predetermined range from the planned drilling location 14. The planned drilling location 14 located inside is skipped, and the planned drilling location 14 located outside the predetermined range is irradiated with laser light. Here, in this embodiment, “scheduled hole 14 located within a predetermined range from one scheduled hole 14” means “a peripheral region of one scheduled hole 14, and one scheduled hole 14. Refers to the planned location 14 located in the “region affected by the heat when the laser beam is irradiated”, more specifically “the divided region adjacent to the divided region including the one scheduled drilling location 14”. The point 14 scheduled to be drilled is indicated. Hereinafter, the laser drilling method according to the present embodiment will be described in detail.

  First, an order is determined for the 36 scheduled holes 14 (preparation step). In determining the order, as shown in FIG. 2A, the sheet 2 is divided into a plurality of divided regions (dividing step). The divided area is formed by dividing the sheet 2 into a column, and more specifically, is an area obtained by dividing the sheet 2 into six so as to correspond to n1 to n6 rows. Hereinafter, the divided regions located in the n1 to n6 rows are referred to as divided regions n1 to n6, respectively. Each of the divided regions n1 to n6 includes six scheduled drilling locations 14 located in the m1 to m6 rows.

  After dividing the sheet 2 into the divided areas n1 to n6, as shown in FIG. 2B, the divided areas n1 to n6 are classified into a plurality of groups. At this time, adjacent divided regions belong to the same group. More specifically, the sheet 2 is divided into two rows so that two adjacent divided regions are included in one group. Thus, the divided areas n5 and n6 belong to the group A1, the divided areas n3 and n4 belong to the group A2, and the divided areas n1 and n2 belong to the group A3.

  After classifying the divided areas n1 to n6 into groups A1 to A3, the processing order (order) of the divided areas n1 to n6 is determined (first order determining step). In order to determine the processing order of the divided areas n1 to n6, first, the priority order in the groups A1 to A3 is determined for each of the divided areas n1 to n6 (first step).

  More specifically, the priority order of the divided regions n1 to n6 is determined as shown in FIG. In FIG. 2B, B1 indicates that the priority order is first, and B2 indicates that the priority order is second. The order of priority is common to the groups A1 to A3. That is, in each group, the priority order of the divided areas located in the lower row is first, and the priority order of the divided areas located in the upper row is second.

  Next, the processing order (order) of the divided regions n1 to n6 is determined in accordance with the determined priority order (second step). At this time, for the divided regions having the same priority order and different groups, the processing order is made continuous. On the other hand, the processing order is set to be discontinuous between adjacent divided regions.

  More specifically, the processing order of the divided regions n1 to n6 is determined as shown in FIG. In FIG. 2C, T1 to T6 indicate the processing order of the divided regions n1 to n6. That is, the divided region n5 having the first priority in the group A1 is the first, the divided region n3 having the first priority in the group A2 is the second, and the divided region having the first priority in the group A3. Let n1 be the third. The divided area n6 having the second priority order in the group A1 is the fourth, the divided area n4 having the second priority order in the group A2, is the fifth, and the divided area n2 having the second priority order in the group A3 is the second. 6th. Adjacent divided areas, for example, divided area n5 and divided area n4 are first and fifth in order, and are not continuous.

  When the processing order of the divided areas n1 to n6 is determined, the processing order of the 36 scheduled holes 14 is determined according to this processing order (second order determination step).

  More specifically, the processing order of the scheduled holes 14 is made to correspond to the processing order of the divided regions n1 to n6. That is, six scheduled drilling locations 14 in the divided region n5, six scheduled drilling locations 14 in the segmented region n3, six scheduled drilling locations 14 in the segmented region n1, six scheduled drilling locations 14 in the segmented region n6, and the divided region n4 It is assumed that the six planned drilling locations 14 and the six planned drilling locations 14 in the divided region n2 are in this order. In addition, the processing order is not ask | required about the six drilling planned locations 14 contained in each of division area | region n1-n6. For example, the order from the m1 column to the m6 column shown in FIG. 2 may be used, or the order from the m6 column to the m1 column may be used. Further, it may be random.

  As described above, the processing order of the 36 drilling scheduled locations 14 is determined. A series of processes for determining the processing order of the planned drilling location 14 is executed by a laser drilling machine or a CAD connected to the laser drilling machine. When it is executed by CAD, it is preferable that the CAD is executed at a timing when the position data of the planned drilling location 14 is analyzed. Further, when the laser drilling machine is executed, it is preferably executed at the timing when the laser drilling machine converts the position of the planned drilling location 14 into a coordinate system suitable for galvano scanning.

  When the processing order of the planned drilling location 14 is determined, the laser drilling is performed on the planned drilling location 14 in accordance with this processing sequence. As the laser light, a pulsed carbon dioxide laser or an ultraviolet YAG laser can be used.

  More specifically, after irradiating the laser beam to the six scheduled holes 14 in the divided region n5, the laser beam is irradiated to the six scheduled holes 14 in the divided region n3. Thereafter, the six scheduled drilling locations 14 in the divided region n1, the six scheduled drilling locations 14 in the segmented region n6, the six scheduled drilling locations 14 in the segmented region n4, and the six scheduled drilling locations 14 in the segmented region n2 in this order. Irradiate light. As a result, 36 through holes 4 are formed in the sheet 2. In the present embodiment, a cycle processing method is applied to laser light irradiation.

  As described above, in the laser drilling method according to the present embodiment, for example, after the laser beam is irradiated to the planned drilling spot 14 in the divided area n5, the scheduled drilling spot 14 in the split area n4 adjacent to the split area n5 is used. The laser beam is irradiated to the planned drilling portion 14 of the divided region n3 which is skipped and separated from the divided region n5.

  Irradiation of the laser beam to the divided region n4 is performed after the divided regions n3, n1, and n6. When the divided region n5 is irradiated with the laser beam, not only the divided region n5 but also the divided region n4 has heat. However, when the divided region n4 has heat, the laser beam is not irradiated and the temperature is lowered. Later, laser light is irradiated again. Therefore, the possibility that heat is accumulated in the divided region n4 is reduced, and deformation of the sheet 2 is suppressed. In addition, as temperature after temperature fall, less than 2000 degreeC is preferable, 1000 degrees C or less is more preferable, 500 degrees C or less is especially preferable, and 100 degrees C or less is the most preferable. In order to irradiate the laser beam when such a temperature is reached, the processing order of the planned drilling location 14 and, in turn, the processing order and priority order of the divided region n5 are determined.

  Further, in the laser drilling method according to the present embodiment, the processing order of the planned drilling locations 14 is determined, and each planned drilling site 14 is irradiated with laser light according to this processing sequence. The processing order of the scheduled holes 14 is determined based on the processing order of the divided regions n1 to n6, and the processing order set in adjacent divided regions, for example, the divided regions n1 and n2, is discontinuous. Therefore, it is possible to reduce the possibility of continuously irradiating adjacent divided regions with laser light.

  Further, in the laser drilling method according to the present embodiment, for example, when the divided region n5 belonging to the group A1 is irradiated with laser light, the divided region n3 belonging to the group A2 is irradiated with laser light next. Since each of the groups A1 to A3 is composed of adjacent divided regions, there is a high possibility that divided regions having different groups belong to each other with a sufficient interval. Therefore, it is possible to more reliably reduce the possibility of continuously irradiating laser light to the divided regions located in the vicinity.

(Second Embodiment)
FIG. 3 is a diagram for explaining a laser drilling method according to the second embodiment. In the laser drilling method according to the present embodiment, as shown in FIG. 3A, first, the sheet 2 is divided into a plurality of divided regions so that one scheduled region 14 is included in one divided region. To do. More specifically, the sheet 2 is divided into 36 divided regions by dividing the sheet 2 into a 6 × 6 grid.

  After the sheet 2 is divided into 36 divided regions, these are classified into nine groups A1 to A9. More specifically, the sheet 2 is divided into two rows and two columns so that four adjacent divided regions are included in one group.

  After the 36 divided areas are classified into nine groups A1 to A9, the priority order in each group is determined for each divided area as shown in FIG. In FIG. 3A, B1 to B4 indicate that the priority order is 1st to 4th. The arrangement of the priority order is common to the groups A1 to A9. That is, in each group, the priority order of the division area located in the lower left is first, the priority order of the division area located in the lower right is second, the priority order of the division area located in the upper left is third, and The priority order of the divided areas to be positioned is the fourth.

  Subsequently, the processing order of the divided regions is determined based on the determined priority order. At this time, the processing order is made continuous between the divided regions having the same priority order and belonging to different groups, and the processing order is made non-continuous between the adjacent divided regions. The order of the 36 divided areas is the order shown in FIG. In FIG. 3B, T1 to T36 indicate that the processing order is 1st to 36th.

  When the processing order of the 36 divided regions is determined, the processing order of the planned drilling location 14 is determined based on this processing order. Then, laser light is irradiated according to the determined processing order. Since only one scheduled hole 14 is included in one divided area, the processing order of the scheduled holes 14 is the same as the processing order of the divided areas. In the present embodiment, as in the first embodiment, a cycle processing method is applied to laser light irradiation.

  Even in such a laser drilling method, the laser beam is not continuously irradiated to the adjacent divided regions, so that heat accumulation can be suppressed.

(Third embodiment)
FIG. 4 is a diagram for explaining a laser drilling method according to the third embodiment. In the laser drilling method according to the present embodiment, the sheet 2 is divided into 36 divided regions as in the second embodiment. These are classified into four groups A1 to A4. More specifically, more specifically, the sheet 2 is divided into three rows and three columns so that nine adjacent divided regions are included in one group.

  After the 36 divided regions are classified into four groups A1 to A4, the priority order in each group is determined for each divided region as shown in FIG. In FIG. 4A, B1 to B9 indicate that the priority order is 1st to 9th. The order of priority is common to the groups A1 to A4. Subsequently, the processing order of the divided regions is determined based on the determined priority order. At this time, the processing order is continued for the divided regions having the same priority order and different groups. Further, the processing order is not continuous between adjacent divided regions. The processing order of the 36 divided regions is set to the order indicated by T1 to T36 in FIG.

  When the processing order of the 36 divided regions is determined, the processing order of the planned drilling location 14 is determined based on this processing order. Then, laser light is irradiated according to the determined processing order. Since only one scheduled hole 14 is included in one divided area, the processing order of the scheduled holes 14 is the same as the processing order of the divided areas. In the present embodiment, as in the first embodiment, a cycle processing method is applied to laser light irradiation. Even in such a laser drilling method, the laser beam is not continuously irradiated to the adjacent divided regions, so that heat accumulation can be suppressed.

(Fourth embodiment)
FIG. 5 is a diagram for explaining a laser drilling method according to the fourth embodiment. In the laser drilling method according to the present embodiment, the sheet 2 is first divided into six divided regions as in the first embodiment. After the sheet 2 is divided into six divided regions, these are classified into two groups A1 and A2. More specifically, the sheet 2 is divided into three rows so that three adjacent divided regions are included in one group. After the six divided areas are classified into two groups A1 and A2, the priority order in each group is determined for each divided area. The arrangement of the priority order is common to the groups A1 and A2, and specifically, as shown in FIG.

  Subsequently, the processing order of the divided regions is determined based on the determined priority order. At this time, the processing order is continued for the divided regions having the same priority order and different groups. Further, the processing order is not continuous between adjacent divided regions. The processing order of the six divided areas is the order shown in FIG.

  When the processing order of the six divided regions is determined, the processing order of the 36 scheduled holes 14 is determined based on this order. More specifically, the order of the planned drilling locations 14 is as follows: six planned drilling locations 14 in the divided region n4, six planned drilling locations 14 in the divided region n1, six planned drilled locations 14 in the divided region n5, and divided region n2. , Six scheduled drilling locations 14 in the divided region n6, and six scheduled drilling locations 14 in the divided region n3. In addition, the order of processing is not ask | required about the six scheduled holes 14 included in each division area.

  In accordance with the determined processing sequence of the planned drilling location 14, the planned drilling location 14 is irradiated with laser light. In the present embodiment, as in the first embodiment, a cycle processing method is applied to laser light irradiation. Even in such a laser drilling method, since adjacent holes are not continuously drilled, there is a possibility that the laser beam is further irradiated with the laser beam by the laser beam irradiation. Becomes lower. Therefore, even when punching the sheet 2 at a narrow pitch, deformation of the sheet 2 due to heat accumulation is suppressed.

(Fifth embodiment)
FIG. 6 is a diagram for explaining a laser drilling method according to the fifth embodiment. In the laser drilling method according to the present embodiment, the sheet 2 is divided into 36 divided regions as in the third embodiment. These are classified into six groups A1 to A6. More specifically, the sheet 2 is divided into two rows and three columns so that six adjacent divided regions are included in one group.

  After the 36 divided areas are classified into six groups A1 to A6, the priority order in each group is determined for each divided area. The order of priority is common to the groups A1 to A6, and specifically, as shown in FIG. Subsequently, the processing order of the divided regions is determined based on the determined priority order. At this time, the processing order is continued for the divided regions having the same priority order and different groups. Further, the processing order is not continuous between adjacent divided regions. The order of the 36 divided regions is the order indicated by T1 to T36 in FIG.

  When the processing order of the 36 divided regions is determined, the processing order of the planned drilling location 14 is determined based on this processing order. Then, laser light is irradiated according to the determined processing order. Since only one scheduled hole 14 is included in one divided area, the processing order of the scheduled holes 14 is the same as the processing order of the divided areas. In the present embodiment, as in the first embodiment, a cycle processing method is applied to laser light irradiation. Even in such a laser drilling method, the laser beam is not continuously irradiated to the adjacent divided regions, so that heat accumulation can be suppressed.

(Sixth embodiment)
FIG. 7 is a view for explaining a laser drilling method according to the sixth embodiment. In the laser drilling method according to the present embodiment, the sheet 2 is divided into 36 divided regions as in the second embodiment. These are classified into four groups A1 to A4. More specifically, the sheet 2 is divided into three rows and three columns so that nine adjacent divided regions are included in one group. After the 36 divided areas are classified into four groups A1 to A4, the priority order in each group is determined for each divided area. The arrangement of the priority order is common to the groups A1 to A4. Specifically, the order is as shown by B1 to B3 in FIG. Note that the divided region located in the n4 row and m1 column, the divided region located in the n5 row and m2 column, and the divided region located in the n6 row and m3 column have the same priority order of B1.

  Subsequently, the processing order of the divided regions is determined based on the determined priority order. At this time, the processing order is continued for the divided regions having the same priority order and different groups. Further, the processing order is not continuous between adjacent divided regions. The order of the 36 divided regions is the order shown in FIG. Note that the processing order is not limited for divided regions having the same priority order and the same group. Therefore, in this embodiment, the order of the regions located in the n4 rows and m1 columns is T5, the order of the regions located in the n5 rows and m2 columns is T4, and the order of the regions located in the n6 rows and m3 columns is T1. For example, the order of the regions located in the n4 rows and m1 columns may be T1, the order of the regions located in the n5 rows and m2 columns may be T5, and the order of the regions located in the n6 rows and m3 columns may be T4. .

  When the processing order of the 36 divided regions is determined, the processing order of the planned drilling location 14 is determined based on this processing order. Then, laser light is irradiated according to the determined processing order. Since only one scheduled hole 14 is included in one divided area, the processing order of the scheduled holes 14 is the same as the processing order of the divided areas. In the present embodiment, as in the first embodiment, a cycle processing method is applied to laser light irradiation. Even in such a laser drilling method, the laser beam is not continuously irradiated to the adjacent divided regions, so that heat accumulation can be suppressed.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the above embodiment.

  For example, in the first to sixth embodiments, the scheduled holes 14 are arranged in 6 rows and 6 columns, but the scheduled holes 14 may be randomly distributed as shown in FIG. In this case, the sheet 2 is divided into row-like divided areas as shown in FIG. 8A or grid-like divided areas as shown in FIG. 8B, and straddling the boundaries of the divided areas. It is preferable to process the hole-scheduled portion 14 that is considered to belong to any one region. When the sheet 2 is divided into a grid, it is ideal that the number of the scheduled holes 14 included in the divided region is one, but as shown in FIG. 14 may not be included, or a divided area including 2 to 4 scheduled holes 14 may occur. In such a case, there is no particular problem. However, if a divided region including three or more scheduled holes 14 is generated, the sheet 2 may be divided more finely (for example, a place having a width of 0.3 mm). The number of divided areas to be grouped is increased (for example, 9 is changed from 4) to increase the number of divided areas to be grouped. Two or less are preferable. In this way, heat accumulation can be further suppressed.

  In the first to sixth embodiments, when the divided region is obtained, the entire sheet 2 is divided. For example, the distribution state of the scheduled holes 14 in the sheet 2 is detected (detection step) and detected. A part of the sheet 2 may be divided into a plurality of divided regions based on the distribution situation. In this case, the processing described above can be applied only to the area of the sheet 2 where the scheduled holes 14 are dense, so that the processing time can be shortened.

  In the first to sixth embodiments, the cycle processing method is applied to the laser beam irradiation, but a burst processing method may be applied. However, from the viewpoint of more effectively suppressing the occurrence of wavy deformation or the like in the sheet 2, it is preferable to use a cycle processing method.

  In the first to sixth embodiments, the divided regions are obtained by dividing the sheet 2 into rows or grids, but the divided shape of the sheet 2 is not limited to this. Further, the number of divided areas and the number of groups are not limited to those described above.

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to the following. In the examples and comparative examples shown below, the processing order of the locations to be drilled was determined by controlling CAD. Further, the number of holes to be drilled is 400, and the holes are arranged in 20 rows and 20 columns.
(Production of sheet)

  A 40 μm thick glass cloth epoxy prepreg (manufactured by Hitachi Chemical Co., Ltd., product name: GEA-679FG) was prepared. A glass cloth epoxy prepreg was prepared by thermally laminating a PET film having a thickness of 12 μm on both sides. Hereinafter, the glass cloth epoxy prepreg laminated with the PET film is referred to as “sheet with PET”, and the glass cloth epoxy prepreg without the PET film laminated is referred to as “single sheet”.

Example 1
In the same manner as in the first embodiment, the processing order of the planned drilling locations was determined. However, since the arrangement of the drilling locations is 20 rows and 20 columns, it is different from the first embodiment in that the number of divided areas is 20 and the number of groups is 10. After determining the processing order of the planned drilling locations, punching was performed on the sheet with PET in the same manner as in the first embodiment.

(Example 2)
In the same manner as in the second embodiment, the processing order of the planned drilling locations was determined. However, it is different from the second embodiment in that the number of divided areas is 400 and the number of groups is 10 with the planned drilling location being 20 rows and 20 columns. After determining the processing sequence of the planned drilling locations, punching was performed on the sheet with PET in the same manner as in the second embodiment. Note that a cycle processing method was applied to laser light irradiation.

(Example 3)
In this embodiment, the actual drilling locations arranged in 20 rows and 20 columns are virtually added by 1 row and 1 column to form 21 rows and 21 columns, and nine adjacent divided areas are grouped into one group. After the sheet with PET was divided into 3 rows and 3 columns so as to be included, the processing order of the locations to be drilled was determined as in the third embodiment. After determining the processing order of the planned drilling locations, punching was performed on the sheet with PET in the same manner as in the third embodiment. However, it was decided not to perform the drilling process for one row and one column, which is generated by dividing as described above, and where the actual drilling location is not arranged. Thereby, it is possible to provide a cooling time for suppressing heat accumulation for such one row and one column. Note that a cycle processing method was applied to the laser light irradiation in this example.

Example 4
Drilling was performed in the same manner as in Example 1 except that the burst processing method was applied to laser light irradiation.

(Example 5)
Excavation processing was performed in the same manner as in Example 2 except that the burst processing method was applied to laser light irradiation.

(Example 6)
Excavation processing was performed in the same manner as in Example 3 except that the burst processing method was applied to laser light irradiation.

(Example 7)
Except that the single sheet was used, drilling was performed in the same manner as in Example 1.

(Example 8)
Except that the single sheet was applied, drilling was performed in the same manner as in Example 2.

Example 9
Except that the single sheet was applied, drilling was performed in the same manner as in Example 3.

(Comparative Example 1)
The processing sequence of the planned drilling locations was based on T1 to T36 shown in FIG. In other words, the processing order is always continuous between the adjacent drilling locations 14. After determining the processing order of the hole-scheduled location, the punched sheet was punched.

(Comparative Example 2)
Drilling was performed in the same manner as in Comparative Example 1 except that the burst processing method was applied to laser light irradiation.

(Comparative Example 3)
Except that the single sheet was applied, drilling was performed in the same manner as in Comparative Example 1.

Examples 1 to 9 and Comparative Examples were set such that the diameter of the planned drilling location was 80 μm, and the array pitch of the planned drilling locations (corresponding to the symbol D shown in FIG. 1) was 150 μm, 175 μm, 200 μm, 225 μm, 250 μm, 275 μm, and 300 μm. When forming holes in 1 to 3, whether or not a wave deformation has occurred in the PET-attached sheet or single sheet, and whether or not the PET-attached sheet or single sheet has been clogged by resin melting Each was examined. The results are shown in Table 1. In Table 1, ◯ indicates that no wavy deformation has occurred, Δ indicates that wavy deformation has slightly occurred, x indicates that wavy deformation has clearly occurred, and xx indicates resin. It shows that the hole has been blocked by melting.

  As shown in Table 1, in Examples 1 to 9, it was confirmed that undulating deformation and hole blocking were less likely to occur than in Comparative Examples 1 to 3. In addition, since the results of Examples 2, 3, 5, 6, 8, and 9 are better than the results of Examples 1, 4, and 7, it is better to reduce the number of scheduled holes included in one divided region. It was found that undulation deformation and hole blockage were suppressed. In addition, since the results of Examples 3, 6, and 9 are better than the results of Examples 2, 5, and 6, the larger the number of divided regions included in one group, the more the wavy deformation and the hole blockage. It was found to be suppressed.

  From the above, when drilling dense laser holes in a sheet-shaped resin material, it is possible to prevent clogging of adjacent holes due to waves and resin melting by changing the drilling order and reducing heat accumulation. It has become clear that it is industrially useful and can contribute to higher density of wiring boards.

It is a perspective view which shows the sheet | seat punched by the laser drilling method concerning 1st Embodiment. It is a figure for demonstrating the laser drilling method concerning 1st Embodiment. It is a figure for demonstrating the laser drilling method concerning 2nd Embodiment. It is a figure for demonstrating the laser drilling method concerning 3rd Embodiment. It is a figure for demonstrating the laser drilling method concerning 4th Embodiment. It is a figure for demonstrating the laser drilling method concerning 5th Embodiment. It is a figure for demonstrating the laser drilling method concerning 6th Embodiment. It is a figure which shows the modification of a drilling plan location. It is a figure for demonstrating the laser drilling method in a comparative example. It is a figure for demonstrating the conventional laser drilling method.

Explanation of symbols

  2 ... sheet, 4 ... through hole, 14 ... scheduled hole location, A1 to A4 ... group, B1 to B36 ... sequence of processing of divided regions, T1 to T36 ... sequence of drilling location, D ... arrangement pitch.

Claims (6)

A laser drilling method for performing a drilling process by sequentially irradiating a laser beam to a plurality of planned drilling locations of a sheet-like member,
For at least some of the plurality of scheduled drilling locations, after the laser beam is irradiated to one scheduled drilling location, the scheduled drilling location located within a predetermined range from the scheduled drilling location is skipped. And irradiating the laser beam to the planned drilling location located outside the predetermined range ,
A preparation step for determining an order for the hole-scheduled portion;
Irradiation step of irradiating the planned drilling spot with the laser beam according to the order of the planned drilling spot determined in the preparation step,
Have
The preparation step includes
A dividing step of dividing the sheet-like member into a plurality of divided regions;
A first order determining step for determining an order for the divided regions divided in the dividing step;
A second order determining step for determining the order of the scheduled holes according to the order of the divided regions determined in the first order determining step,
At least a part of the plurality of divided regions includes the scheduled hole,
In the first order determination step, for the adjacent divided areas, the order of the divided areas is discontinuous,
The dividing step includes
Dividing the sheet-like member into the plurality of divided regions, and classifying the plurality of divided regions into a plurality of groups so that the adjacent divided regions belong to the same group,
The first order determination step includes:
A first step of determining a priority order within the group for the divided areas;
A second step of determining the order of the divided regions according to the priority order determined in the first step;
Including
In the second step, the laser drilling method is characterized in that the order of the divided regions is made continuous between the divided regions having the same priority order and belonging to different groups . 2. The laser drilling method according to claim 1, wherein the divided region is formed by dividing the sheet-like member into a row. The laser drilling method according to claim 1, wherein the divided region is formed by dividing the sheet-like member into a lattice shape. The preparatory step further includes a detection step of detecting a distribution situation of the planned drilling locations in the sheet-like member,
The division step is characterized in that a part of the sheet-like member is divided into a plurality of the divided regions based on the distribution situation of the planned drilling locations detected in the detection step.
The laser drilling method according to any one of 1 to 3 . The laser drilling method according to any one of claims 1 to 4 , wherein the sheet-like member is made of a mixture containing a resin. The laser beam is a laser drilling method according to any one of claim 1 to 5, characterized in that a pulsed carbon dioxide laser or UV YAG laser.

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