Laser processing method

Abstract

This technology provides the ability to maintain or improve the quality of machining even when drilling multiple holes at a narrow pitch. [Solution] The laser processing method includes the steps of: forming a protective sheet on the surface of a substrate (S1); setting a first group of drilling positions and a second group of drilling positions on the surface of the substrate such that, if the first pitch between a plurality of drilling positions on the surface of the substrate is smaller than the processing diameter of the protective sheet, the second pitch is greater than or equal to the processing diameter of the protective sheet (S0); performing a first drilling process by irradiating the first group of drilling positions with a laser to form a first hole (S2); forming a new protective sheet (S3); performing a second drilling process by irradiating the second group of drilling positions with a laser to form a second hole (S4); and removing the protective sheet (S5).

Description

Technical Field

[0001] The present disclosure relates to laser processing technology. In particular, it relates to a laser processing method suitable for drilling a glass ceramic substrate using a carbon dioxide laser.

Background Art

[0002] In the laser processing of the prior art example, for example, as described in Patent Document 1, a protective sheet is attached to the surface of the substrate, and the laser light from the laser oscillator is irradiated onto the substrate from the protective sheet side to perform drilling.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when performing drilling of a plurality of holes (corresponding drilling positions) at a narrow pitch such as a hole diameter drilled on the upper surface of the protective sheet (hole diameter on the upper surface of the protective sheet) or less, there are the following problems. Between adjacent drilling positions, since the hole diameter on the upper surface of the protective sheet partially overlaps, a portion where there is no or little protective sheet occurs on a part of the upper surface of the glass ceramic substrate. Therefore, due to laser irradiation, molten glass ceramic components adhere to a part of the upper surface of the glass ceramic substrate, and the hole shape may be distorted because the irradiation of the laser light is too strong. As a result, the processing quality deteriorates.

[0005] An object of the present disclosure is to provide a technology that can maintain or improve the processing quality even when performing drilling of a plurality of holes at a narrow pitch as described above with respect to the above laser processing technology.

Means for Solving the Problems

[0006] A typical embodiment of this disclosure has the following configuration. One embodiment is a laser processing method for drilling holes in a substrate using a laser, comprising the steps of: forming a protective sheet on the surface of the substrate; setting a first group of drilling positions and a second group of drilling positions on the surface of the substrate such that, if the first pitch between a plurality of drilling positions for a plurality of holes on the surface of the substrate is smaller than the processing diameter of the protective sheet, the second pitch is greater than or equal to the processing diameter of the protective sheet; performing a first drilling process by irradiating the first group of drilling positions with a laser to form first holes; removing the protective sheet on the surface of the substrate that has been processed by the first drilling process and forming a new protective sheet; performing a second drilling process by irradiating the second group of drilling positions with a laser to form second holes; and removing the protective sheet on the surface of the substrate that has been processed by the second drilling process. [Effects of the Invention]

[0007] According to a representative embodiment of this disclosure, the laser processing technology described above can maintain or improve processing quality even when drilling multiple holes at such a narrow pitch. Other issues, configurations, and effects are shown in the embodiments for carrying out the invention. [Brief explanation of the drawing]

[0008] [Figure 1] An example configuration of a laser processing apparatus for performing the laser processing method of Embodiment 1 is shown. [Figure 2] An example of the configuration of the workpiece substrate in the laser processing method of Embodiment 1 is shown. [Figure 3A] This shows an example of single-sided processing and through-hole drilling of a substrate in the laser processing method of Embodiment 1. [Figure 3B] This shows an example of single-sided processing of a substrate and non-through-hole processing in the laser processing method of Embodiment 1. [Figure 4] An example of the flow configuration in the laser processing method of Embodiment 1 is shown. [Figure 5A] This shows the state of the substrate during the first cycle processing (step S2) in the laser processing method of Embodiment 1. [Figure 5B] This shows the state of the substrate during the replacement of the protective sheet (step S3) in the laser processing method of Embodiment 1. [Figure 5C] This shows the state of the substrate during the second cycle processing (step S4) in the laser processing method of Embodiment 1. [Figure 5D] This shows the state of the substrate after the removal of the protective sheet (step S5) in the laser processing method of Embodiment 1. [Figure 6] An example of the flow configuration in the laser processing method of Embodiment 2 is shown. [Figure 7A] This shows the state of the substrate during the first cycle processing (step S21) of the first group of surfaces in the laser processing method of Embodiment 2. [Figure 7B] This shows the state of the substrate during the first cycle processing (step S22) of the first group on the back surface in the laser processing method of Embodiment 2. [Figure 7C] This shows the state of the substrate during the second cycle processing of the second group on the front surface and the second cycle processing of the second group on the back surface (steps S41, S42) in the laser processing method of Embodiment 2. [Figure 7D] This shows the state of the substrate after the removal of the protective sheet (step S5) in the laser processing method of Embodiment 2. [Figure 8A] This shows the state of the substrate during surface cycle processing in the first configuration example (first pitch) of the comparative example laser processing method. [Figure 8B] This shows the state of the substrate during surface cycle processing in the second configuration example (second pitch) of the comparative example laser processing method. [Figure 8C] This shows a state in which molten components are attached to a part of the surface in the second configuration example (second pitch) of the comparative example laser processing method.

Best Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same parts are generally denoted by the same reference numerals, and repeated descriptions are omitted. In the drawings, the representation of the components may not represent the actual position, size, shape, range, etc. for the purpose of facilitating the understanding of the invention, but there is no intention of limitation.

[0010] [Problems, etc.] FIGS. 8A to 8C are explanatory diagrams for explaining problems, etc. in the laser processing method of the comparative example. In the comparative example of FIG. 8A etc., the case of drilling the substrate 1 which is a glass ceramic substrate using a carbon dioxide laser is shown. In particular, the case of single-sided processing for drilling on the surface 1A (in other words, the upper surface) of the substrate 1, and the case of forming a through hole 1C as a hole are shown.

[0011] FIG. 8A shows the case of the first configuration example regarding the pitch of a plurality of drilling positions M (in other words, processing target positions, laser irradiation positions, etc.) on the surface 1A of the substrate 1. The first pitch in the first configuration example is set as P1. Note that the illustrated X-axis and X direction indicate the planar direction of the substrate 1, and the Z-axis and Z direction indicate the thickness direction and the vertical direction of the substrate 1. The +Z side is the surface (upper surface) 1A of the substrate 1, and the -Z side is the back surface (lower surface) 1B of the substrate 1.

[0012] A protective sheet 2A (in other words, a protective film) is provided on the surface 1A (in other words, the drilling target surface) of the substrate 1. The protective sheet 2A is provided to prevent the influence on the surface 1A of the substrate 1 by the molten components due to laser irradiation. As a plurality of drilling positions M on the surface 1A of the substrate 1, there are M1, M2, etc., and their position coordinates are determined. In FIG. 8A, the pitch of the plurality of drilling positions M in the X direction is P1.

[0013] In the comparative example, cycle machining is performed on a plurality of holes (corresponding drilling positions). In the cycle machining, the laser is sequentially irradiated onto each drilling position M. As a result, a hole diameter (in other words, the upper surface hole diameter of the protective sheet, the processing diameter of the protective sheet, etc.) 801 is formed on the upper surface of the protective sheet 2A. This hole diameter 801 is different from the hole diameter 802 (in other words, the upper surface hole diameter of the substrate, etc.) of the hole (through hole 1C) on the upper surface 1A of the substrate 1, and is larger than that.

[0014] In the case of the first configuration example (first pitch) of FIG. 8A, the pitch P1 is not less than the hole diameter 801. Therefore, a part 803 of the protective sheet 2A remains on the surface 1A of the substrate 1. The part 803 of the protective sheet 2A can prevent the influence of the molten component of the glass-ceramic substrate 1 on the upper surface 1A of the substrate 1. In other words, the corresponding upper surface 1A can be protected from the molten component by the part 803 of the protective sheet 2A.

[0015] Note that in this example, in the case of machining a through hole 1C that penetrates from the surface 1A side to the back surface 1B side of the substrate 1 as the hole. A hole diameter 804 of the through hole 1C is formed on the back surface 1B side of the substrate 1. This hole diameter 804 is smaller than the hole diameter 802 on the surface 1A side. Since it is the drilling process of the through hole 1C, a protective sheet 2B is also provided on the back surface 1B side of the substrate 1. When the laser irradiated from the surface 1A side penetrates to the back surface 1B side, a hole diameter (in other words, the lower surface hole diameter of the protective sheet, the processing diameter of the protective sheet, etc.) 805 is also formed on the lower surface of the protective sheet 2B. This hole diameter 805 is smaller than the upper surface hole diameter 801 of the protective sheet.

[0016] Note that not limited to this example, for the formation of the hole, processing such as laser irradiation from the back surface 1B side may be performed. That is, not limited to single-sided processing, front and back processing may be performed. Also, not limited to the through hole 1C, non-through hole processing may be performed.​​​In this comparative example, as shown in Figure 8B, we consider a case where we intend to drill holes at multiple drilling locations M on the surface 1A of the substrate 1 at a pitch of 801 or less in diameter on the upper surface of the protective sheet. Figure 8B shows a second configuration example regarding the pitch of the multiple drilling locations M on the surface 1A of the substrate 1. This second pitch, pitch P2, is smaller than pitch P1 in Figure 8A, and is 801 or less in diameter.

[0018] In this case, for example, the hole diameters 801 on the upper surface of the protective sheet partially overlap between adjacent drilling positions M in the X direction. Part 806 indicates the overlapping portion of the hole diameters 801. Due to this overlap, as a result of the laser irradiation causing the protective sheet 2A to be scraped away, a portion 807 on the surface 1A of the substrate 1 (i.e., the portion between adjacent holes) is missing or has a reduced amount of protective sheet 2A. Part 807 is, in other words, the portion where the protective sheet has been peeled off.

[0019] Therefore, in some cases of unit 807, as shown in Figure 8C, molten glass ceramic (molten component) adhered to the upper surface 1A of the substrate 1, and the hole shape was distorted due to excessive laser irradiation. This resulted in a decrease in the quality of laser processing (drilling).

[0020] Figure 8C is an explanatory diagram (cross-sectional view and top view) corresponding to the case in Figure 8B. When holes were drilled with a pitch P2 of 801 or less on the top surface of the protective sheet, a state occurred where the protective sheet 2A was missing in the overlap portion 807. In this portion 807, glass ceramic (molten component) melted by the laser adhered to the top surface 1A of the substrate 1. Part 808 is the area where the glass ceramic (molten component) adhered. As a result, distortion occurred in the hole shape (hole diameter 802) of the hole (through hole 1C) in the substrate 1 after processing.

[0021] In response to the above-mentioned challenges, this embodiment provides a technology that can maintain or improve quality even when drilling multiple holes at a narrow pitch, such as the diameter of the holes on the top surface of the protective sheet.

[0022] <Embodiment 1> The laser processing method of Embodiment 1 will be described using Figures 1 and subsequent figures.

[0023] [Laser processing equipment] Figure 1 shows the configuration of a laser processing apparatus for performing the laser processing method of Embodiment 1. The configuration in Figure 1 is typical. The laser processing apparatus in Figure 1 includes an overall control unit 26, a laser oscillator 22 (carbon dioxide laser oscillator), an acousto-optic modulator 23 (abbreviated as AOM), a galvanometer scanner 24, and a damper 25. A workpiece substrate 21, which is the object to be processed, is placed on a stage or the like (not shown).

[0024] The laser oscillator 22 is a carbon dioxide laser oscillator that emits a laser pulse L1. The AOM 23 is an acousto-optic modulator that splits the laser pulse L1 output from the carbon dioxide laser oscillator 22 into two directions: a processing direction and a non-processing direction. The galvanometer scanner 24 is a galvanometer scanner that sequentially irradiates the laser pulse L2, which has been split in the processing direction by the AOM 23, onto the drilling positions on the workpiece substrate 21. This galvanometer scanner 24 is designed to scan the laser pulse L2 by rotating. The damper 25 is a damper that absorbs the laser pulse L3, which has been split in the non-processing direction by the AOM 23.

[0025] The overall control unit 26 is a control unit (in other words, a controller, etc.) that controls the operation of the entire laser processing apparatus and its various parts. The overall control unit 26 includes a laser oscillation control unit 27, an AOM control unit 28, and a galvanometer control unit 29. The overall control unit 26 also includes a processor, etc. The processor is composed of a semiconductor device such as a CPU. Note that the processing by the overall control unit 26 is not limited to software program processing, but may also be implemented with a dedicated circuit.

[0026] The laser oscillation control unit 27 outputs a laser oscillation command signal S to the carbon dioxide laser oscillator 22, instructing the oscillation of individual laser pulses L1 in the carbon dioxide laser oscillator 22. The AOM control unit 28 outputs an AOM drive signal D to the AOM 23, controlling the branching operation of the AOM 23. The galvanometer control unit 29 outputs a galvanometer operation control signal G to the galvanometer scanner 24, instructing the operation of the galvanometer scanner 24.

[0027] The AOM drive signal D, when it is ON, splits the laser pulse L1 input to AOM23 in the processing direction to become laser pulse L2, and at all other times, splits it into a laser pulse L3 in the non-processing direction.

[0028] The galvanometer operation control signal G keeps the galvanometer scanner 24 stationary during its off-times and rotates it during its on-times. With the galvanometer scanner 24 stationary, the laser is shone onto one drilling position, and as the galvanometer scanner 24 rotates, the laser pulse L2 is shone onto the next drilling position.

[0029] The workpiece substrate 21 is a glass-ceramic substrate 1, which is the substrate 1 to be drilled, with a protective sheet 2 provided on it (Figure 2).

[0030] [Work board] Figure 2 shows the workpiece substrate 21. A protective sheet 2A is attached to the upper surface 1A of the substrate 1 via adhesive 3A. Similarly, a protective sheet 2B is attached to the lower surface 1B of the substrate 1 via adhesive 3B. The protective sheets 2 (2A, 2B) are designed to be removable without leaving any adhesive (3A, 3B) on the substrate 1. Regarding the drilling position M1, the dashed area indicates the part that will melt when irradiated with a laser (similar to the area of ​​the through hole 1C in Figure 8A).

[0031] On the upper surface 1A of the substrate 1, for example, there are multiple drilling positions M in the X direction, such as M1, M2, ... The pitch P of the multiple drilling positions M is assumed to be a narrow pitch of 801 or less in diameter of the hole on the upper surface of the protective sheet, similar to the pitch P2 in Figure 8B. As will be described later, in this embodiment, the odd-numbered {M1, M3, ...} of the multiple drilling positions M are designated as the first group (first drilling position group) G1, and the even-numbered {M2, M4, ...} which are shifted by 1 pitch from the first group G1 are designated as the second group (second drilling group) G2. The first group G1 corresponds to the first group of holes and the first cycle processing, and the second group G2 corresponds to the second group of holes and the second cycle processing.

[0032] In the laser processing apparatus shown in Figure 1, the formation of multiple holes in the workpiece substrate 21 (for example, through-hole 1C in Figure 3A, or non-through-hole 1D in Figure 3B) is performed by cycle processing. Cycle processing involves moving the drilling position (laser irradiation position) while irradiating each drilling position with one laser pulse (unit amount), and repeating the same operation the required number of times once all drilling positions are completed.

[0033] Figure 3A shows an example of the hole shape when forming a through hole 1C, and Figure 3B shows an example of the hole shape when forming a non-through hole 1D. In either case, the laser processing method shown in this embodiment is effective. The following explanation will mainly describe the case of single-sided processing to form a through hole 1C as an example.

[0034] [Laser processing method flow chart] Figure 4 shows the flow of the laser processing method of Embodiment 1. In step S0, the laser processing apparatus in Figure 1 sets up the processing. The settings include setting that it is single-sided processing, processing of through holes 1C, multiple drilling positions M (especially groups), pitch, and cycle processing. In other words, the settings include setting parameters / recipe / program related to laser irradiation. In this embodiment, for cycle processing of multiple drilling positions M as shown in Figure 2, the drilling positions are divided into groups so that the pitch (second pitch) is longer than the hole diameter 801 on the top surface of the protective sheet compared to the original narrow pitch (first pitch), and the cycle processing pitch (second pitch) for each group is set. This pitch is set to a pitch of more than twice the original pitch (pitch P in Figure 2) (2P in Figure 5A).

[0035] Figure 5A shows the setting of the cycle machining pitch for each group. In this example, this pitch is twice the original pitch P (2P). The drilling positions M and cycle machining are divided into two parts: the first cycle machining for the first drilling position group G1 in Figure 2, and the second cycle machining for the second drilling position group G2. In other words, this pitch (2P) is such that, in the scanning direction (e.g., X direction), the drilling positions that are the laser irradiation targets are set while skipping one or more (e.g., one) drilling positions. In other words, this pitch (2P) is such that, in the scanning direction, the laser irradiation target drilling positions M and non-target drilling positions M are set alternately.

[0036] In this example, we show a case where the group is divided into two and the pitch is doubled (2P) from the original pitch. However, this is not the only option; it is also possible to divide the group into three or more and set the pitch to three times or more from the original pitch, for example.

[0037] In step S1 of Figure 4, a protective sheet 2A is formed on the surface 1A of the substrate 1, and a protective sheet 2B is formed on the back surface 1B. Step S1 corresponds to the state of the work substrate 21 as shown in Figure 2. Multiple holes (through holes 1C) are drilled at positions M on the surface 1A of the substrate 1. In this example, since through holes are being formed, a protective sheet 2B is also formed on the back surface 1B to protect the back surface 1B.

[0038] In step S2, the laser processing apparatus performs a first cycle of processing on the first group of drilling positions G1 (Figure 2) among a plurality of drilling positions M on the surface 1A of the substrate 1.

[0039] Figure 5A shows the state of the workpiece substrate 21 during the first cycle machining in step S2. The pitch 2P of the first drilling position group G1 in the first cycle machining is set to a pitch of 801 or more, which is greater than or equal to the protective sheet machining diameter, as shown in Figure 5A. The first drilling position group G1 in the first cycle machining consists of odd-numbered drilling positions such as M1, M3, ...

[0040] Alignment marks 510 (e.g., through holes) are pre-formed on the substrate 1 at predetermined positions. Multiple drilling positions M are set based on the alignment marks 510. The laser processing apparatus performs a first cycle of processing on the drilling positions M1, M3, etc. of the first group G1 while checking the alignment marks 510. In the first cycle of processing, the laser is sequentially irradiated onto each drilling position, and the drilling process progresses. The cycle processing is repeated the required number of times depending on the desired hole depth, etc. A hole diameter 801 (processed hole) is created in the protective sheet 2A due to the processing. As a result of repeating the first cycle processing, multiple holes 501 (through holes 1C) are formed in the first drilling position group G1.

[0041] In the first cycle of machining, the pitch (second pitch) of the first drilling position group G1 is set to satisfy the condition that the pitch (2P) is equal to or greater than the protective sheet machining diameter of 801. By satisfying this condition, in the first cycle of machining, it is possible to prevent the abrasion of the protective sheet 2A due to the overlap of the protective sheet machining diameter 801 between adjacent drilling positions M1, M3, etc., as shown in Figures 8B and 8C, as well as the adhesion of glass ceramic molten components and the occurrence of distortion of the hole shape. In Figure 5A, in the portion 503 between adjacent holes 501 on the upper surface 1A of the substrate 1, a sufficient amount of protective sheet 2A remains.

[0042] Furthermore, the laser processing of hole 501 (through hole 1C) creates a hole in the protective sheet 2B on the back side 1B that corresponds to the hole position M and the diameter of the through hole 1C. The hole diameter 805 (bottom hole diameter of the protective sheet) in this hole is smaller than the top hole diameter 801 of the protective sheet (same as in Figure 8A). Therefore, there is no overlap between adjacent bottom hole diameters 805 of the protective sheets, and the problems shown in Figure 8B, etc., do not occur.

[0043] In step S3, the protective sheet 2A with the processed hole (hole diameter 801) on the surface 1A of the substrate 1 is removed (in other words, peeled off), and replaced with a new protective sheet 2A (2A').

[0044] Figure 5B shows the state after replacing the protective sheet 2A in step S3. The protective sheet 2A in Figure 5A is removed and a new protective sheet 2A(2A') is applied.

[0045] In Embodiment 1 (Figures 5A to 5D), only one side of the surface 1A is processed, and with the protective sheet 2B on the back surface 1B present, the hole diameter 805 on the exit side does not overlap between adjacent drilling positions M (Figure 5C). In such a case, it is not necessary to replace the protective sheet 2B on the back surface 1B with a new one in step S3.

[0046] As a variation, if overlap occurs in the protective sheet 2B on the back surface 1B (i.e., the back surface 1B has the same problems as the front surface 1A), the protective sheet 2B on the back surface 1B may also be replaced with a new one, just as it is on the front surface 1A.

[0047] In step S4 of Figure 4, the laser processing apparatus performs a second cycle of processing on the second group of drilling positions G2 (Figure 2) among the multiple drilling positions M on the surface 1A of the substrate 1.

[0048] Figure 5C shows the state of the workpiece substrate 21 during the second cycle machining in step S4. The pitch of the second drilling position group G2 in the second cycle machining is the same as in the first cycle machining, with a pitch of 801 or more (2P) for the protective sheet machining diameter. The drilling positions in drilling position group G2 are even-numbered positions such as drilling positions M2, M4, ... The drilling positions in the second drilling position group G2 are shifted by 1 pitch (P in Figure 2) relative to the first drilling position group G1.

[0049] The laser processing device performs a second cycle of processing on the drilling positions M2, M4, etc., of the second group G2, while checking the alignment marks 510. In the second cycle of processing, the laser is sequentially irradiated onto each drilling position, and the drilling process progresses. Depending on the desired hole depth, the cycle processing is repeated the required number of times. A hole diameter 801 (processed hole) is created in the protective sheet 2A due to the processing. As a result of repeating the second cycle processing, multiple holes 502 (through holes 1C) are formed in the second drilling position group G2. The holes 502 formed in the second cycle processing have the same shape as the holes 501 formed in the first cycle processing.

[0050] In the second cycle of machining, the pitch of the second drilling position group G2 (second pitch) is set to satisfy the condition that the pitch (2P) is equal to or greater than the protective sheet machining diameter of 801, similar to the first cycle of machining. By satisfying this condition, in the second cycle of machining, it is possible to prevent the abrasion of the protective sheet 2A due to the overlap of the protective sheet machining diameter 801 between adjacent drilling positions M2, M4, etc., as shown in Figures 8B and 8C, as well as the adhesion of glass ceramic molten components and the occurrence of distortion of the hole shape. In Figure 5A, in the portion 504 between adjacent holes 502 on the upper surface 1A of the substrate 1, a sufficient amount of protective sheet 2A remains.

[0051] After the target holes (501, 502) are formed up to step S4 in Figure 4, in step S5, the laser processing apparatus removes the protective sheet 2A from the front surface 1A and the protective sheet 2B from the back surface 1B of the substrate 1.

[0052] Figure 5D shows the state after the removal of protective sheets 2A and 2B in step S5. Multiple holes (501, 502) are formed on the substrate 1 at multiple drilling positions M{M1, M2, ...}.

[0053] As a modification, additional processing may be performed on the back surface 1B during the processing in step S2 or step S4. For example, laser irradiation, polishing, or wet etching may be used to enlarge or adjust the shape of the hole diameter (hole diameter 804 in Figure 8A) on the back surface 1B. Alternatively, as shown in Figure 3B, a non-through hole 1D may be formed from the front surface 1A, and then some processing, such as laser irradiation, polishing, or wet etching, may be performed to change the non-through hole 1D into a through hole 1C.

[0054] As described above, in both the first and second cycle processing, a sufficient amount of protective sheet 2A remains on a portion of the upper surface 1A of the substrate 1, that is, the portion between adjacent holes (503, 504), thus preventing the adhesion of glass ceramic melted by the laser.

[0055] According to the laser processing method of Embodiment 1 described above, even when laser processing multiple holes in a glass ceramic substrate with a narrow pitch, such as a pitch smaller than the hole diameter on the top surface of the protective sheet, the influence of molten components on the substrate surface can be prevented, thereby maintaining or improving the quality of the processing. The narrow pitch mentioned above is, for example, in Figure 5A, a pitch P of approximately 1.5 times the hole diameter 802 of hole 501.

[0056] <Embodiment 2> Embodiment 2 will now be described. The basic configuration of Embodiment 2 and others is the same as and common to Embodiment 1, and below, the components that differ in Embodiment 2 and others from Embodiment 1 will be mainly described. Embodiment 2 is a modification of Embodiment 1 and shows the case where front and back processing is performed and the processing of non-through holes is performed.

[0057] When performing front and back processing, the main difference from the single-sided processing in Embodiment 1 is that, in addition to the first and second cycle processing on the front surface 1A side of the substrate 1, the same first and second cycle processing is also performed on the back surface 1B side of the substrate 1.

[0058] Figure 6 shows the flow of the laser processing method of Embodiment 2. Step S2 in Figure 4 is replaced by steps S21 and S22 in Figure 6, and step S4 in Figure 4 is replaced by steps S41 and S42 in Figure 6. In addition, one difference in the content of the steps is that in step S3, both the protective sheet 2A on the surface 1A and the protective sheet 2B on the back surface 1B are replaced with new protective sheets (2A', 2B').

[0059] In the machining settings of step S0, settings such as groups and pitches corresponding to front and back machining are made. The concept of drilling position groups and pitches is the same as in Embodiment 1. The drilling position groups and pitches are set so that peeling does not occur on both the front and back sides due to overlap of the machining diameter of the protective sheet.

[0060] In step S1, a protective sheet 2A is formed on the front surface 1A of the substrate 1, and a protective sheet 2B is formed on the back surface 1B (same as in Figure 2).

[0061] In step S21, the laser processing apparatus performs a first cycle of processing on the first drilling group G1 of surface 1A.

[0062] In step S22, the laser processing device performs the first cycle processing (third cycle processing when considering the entire surface including both the front and back) on the first drilling group G1 on the back surface 1B (the third drilling group when considering the entire surface including both the front and back).

[0063] In step S3, the protective sheet 2A on the surface 1A side with the processed holes and the protective sheet 2B on the back surface 1B side are replaced with new protective sheets (2A', 2B').

[0064] In step S41, the laser processing apparatus performs a second cycle of processing on the second drilling group G2 of surface 1A.

[0065] In step S42, the laser processing device performs a second cycle of processing (the fourth cycle of processing when considering the entire surface including both sides) on the second drilling group G2 on the back surface 1B (the fourth drilling group when considering the entire surface including both sides).

[0066] Figure 7A shows the state of the workpiece substrate 21 in step S21. The hole diameter 711 is assumed to be the machining diameter of the protective sheet 2A on the surface 1A side. In cycle machining, a pitch for cycle machining (second pitch) is set for each group of cycle machining with respect to the original pitch (first pitch) so that there is no overlap of hole diameter 711 between adjacent drilling positions M. In this example, this pitch is twice the original pitch P (2P), as is the case in Embodiment 1, and is a pitch greater than or equal to the hole diameter 711.

[0067] On surface 1A, the first cycle of machining is performed on the first drilling group G1{M1, M3, ...}. This forms a hole 701 (non-through hole 1D). In this example, this hole 701 (non-through hole 1D) is approximately halfway along the thickness direction (Z direction) of the substrate 1.

[0068] Figure 7B shows the state of the workpiece substrate 21 in step S22. On the back surface 1B, the first cycle of machining is performed on the first drilling group G1{M1, M3, ...} at the same pitch (2P) as on the front surface 1A side. This forms a hole 702 (non-through hole 1D). In this example, this hole 702 (non-through hole 1D) is vertically symmetrical to the hole 701 on the front surface 1A side and has a depth to approximately the middle of the thickness direction (Z direction) of the substrate 1.

[0069] Figure 7C shows the state of the workpiece substrate 21 in steps S41 and S42. In step S41, a second cycle of machining is performed on the second drilling group G2{M2, M4, ...} on the surface 1A. This forms a hole 703 (non-through hole 1D). Similarly, in step S42, a second cycle of machining is performed on the second drilling group G2{M2, M4, ...} on the back surface 1A. This forms a hole 704 (non-through hole 1D).

[0070] Figure 7D shows the state of the workpiece substrate 21 after the protective sheets (2A, 2B) are removed in step S5. Multiple holes (701, 702, 703, 704) are formed on the front surface 1A and the back surface 2A.

[0071] Furthermore, from the state shown in Figure 7D, additional processing (for example, wet etching of the non-penetrating portion in the middle of the Z direction) may be performed to open up hole 701 on the surface 1A side and hole 702 on the back surface 1B side to form a single through hole, and to open up hole 703 on the surface 1A side and hole 704 on the back surface 1B side to form a single through hole.

[0072] In the example shown in Figure 6, the cyclic processing is described in the order of the first group on the front surface 1A, the first group on the back surface 1B, the second group on the front surface 1A, and the second group on the back surface 1B. However, the order is not limited to this and can be changed. For example, it is also possible to perform the cyclic processing in the order of the first group on the front surface 1A, the second group on the front surface 1A, the first group on the back surface 1B, and the second group on the back surface 1B. Depending on the order, the protective sheet should be replaced as appropriate.

[0073] According to the laser processing method of Embodiment 2 described above, even when performing laser processing on both sides and when laser processing multiple holes in a glass ceramic substrate at a narrow pitch, the influence of molten components on the substrate surface can be prevented on both sides, thereby maintaining or improving the quality of the processing.

[0074] Although embodiments of this disclosure have been described in detail above, the invention is not limited to the embodiments described above and can be modified in various ways without departing from the gist of the invention. Each embodiment can be modified by adding, deleting, or replacing components, except for essential components. Unless otherwise specified, each component may be singular or plural. Combinations of each embodiment and its variations are also possible. [Explanation of Symbols]

[0075] 1...Substrate, 1A...Front surface, 1B...Back surface, 2(2A,2B)...Protective sheet, 21...Workpiece substrate, 501,502...Hole, M...Hole drilling position, P,2P...Pitch.

Claims

1. A laser processing method that uses a laser to drill holes in a substrate, The steps include forming a protective sheet on the surface of the substrate, The steps include setting a first group of drilling positions and a second group of drilling positions such that, when the first pitch between multiple drilling positions for multiple holes on the surface of the substrate is smaller than the processing diameter of the protective sheet, the second pitch is greater than or equal to the processing diameter of the protective sheet, The steps include: forming a first hole by performing a first drilling operation by irradiating the first group of drilling positions with a laser; The steps include removing the protective sheet with holes drilled in it by the first drilling process on the surface of the substrate, thereby forming a new protective sheet, The steps include: forming a second hole by performing a second drilling process by irradiating the second group of drilling positions with a laser; The step of removing the protective sheet from which the processed holes have been made by the second drilling process on the surface of the substrate, A laser processing method having the following characteristics.

2. In the laser processing method according to claim 1, The first drilling process is a first cycle process in which a laser is irradiated while moving the target position for each drilling position in the first drilling position group, The second drilling process is a second cycle process in which a laser is irradiated while moving the target position for each drilling position in the second drilling position group. Laser processing method.

3. In the laser processing method according to claim 1, The aforementioned laser is a carbon dioxide laser, The aforementioned substrate is a glass ceramic substrate, The protective sheet is formed by adhesive bonding. Laser processing method.

4. In the laser processing method according to claim 1, The steps include forming a second protective sheet on the back surface of the substrate, The steps include setting a third group of drilling positions and a fourth group of drilling positions such that, if the third pitch between multiple drilling positions for multiple holes on the back surface of the substrate is smaller than the processing diameter of the second protective sheet, the pitch becomes a fourth pitch which is greater than or equal to the processing diameter of the second protective sheet, The steps include: forming a third hole by performing a third drilling operation by irradiating the third group of drilling positions with a laser; The steps include removing the second protective sheet with holes drilled in it by the third drilling process on the back surface of the substrate, thereby forming a new second protective sheet, The steps include: forming a fourth hole by performing a fourth drilling operation by irradiating the fourth group of drilling positions with a laser; The steps include removing the second protective sheet, which has been drilled with holes by the fourth drilling process on the back surface of the substrate, A laser processing method having the following characteristics.

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