Substrate processing method

Abstract

The present invention addresses the problem of providing a substrate processing method capable of forming a flat surface for positioning on the bottom surface of a recess and also capable of preventing the occurrence of burrs. The solution is characterized by comprising a first step for forming a pre-hole (20) in an M-shaped first foot region using a drill (DR) having a small diameter, and a second step for cutting while moving a milling cutter (RT) along a substantially M-shaped trajectory (TK) in a direction from the first foot region side to the second foot region side, a milling cutter is moved along a trajectory (KT) that moves in a first leg region so as not to expand a pre-hole, linearly between the first leg region and a second leg region, and in the second leg region to a position deeper than a bottom surface (11) of a recess (10), whereby a planar bottom surface can be formed by expanding the space between deep-cut portions (12, 13) of both substantially M-shaped legs. Burrs generated by drill bit machining can be removed through subsequent milling cutter machining.

Description

Technical Field

[0001] The present invention relates to a substrate processing method for forming a narrow recess having a planar bottom surface at the center on the outer peripheral edge of a printed circuit board. Background Art

[0002] When processing the outer shape of a printed circuit board, in order to prevent burrs or broken residues from being generated, a milling cutter is mainly used for processing. Milling cutter processing is a method of performing cutting and other processing while moving a cylindrical milling cutter (Router-bit, also simply referred to as Router) having a cutting edge on its side along a given trajectory on a substrate in one direction. For example, methods of cutting a printed circuit board by milling cutter processing are disclosed in Patent Documents 1 and 2.

[0003] In the processing method described in Patent Document 1, a forward rotation milling cutter is moved toward one end side of a hole portion in such a manner that the rotation direction faces the inner wall surface direction of the hole portion to cut the substrate, and the cutting is ended when the one end side of the hole portion is cut. Thereafter, a reverse rotation milling cutter is moved toward the other end side of the hole portion in such a manner that the rotation direction faces the inner wall surface direction of the hole portion to cut the substrate, and the cutting is ended when the other end side of the hole portion is cut. Thus, the printed circuit board is cut in a manner of crossing the hole portion formed in the printed circuit board.

[0004] In the processing method described in Patent Document 2, in the case of cutting out a plurality of printed circuit boards from one sheet, by forming the corners of each printed circuit board into an arc shape convex toward the inside of the substrate, a place (V-shaped cutting) where a groove having a V-shaped cross section for separating the printed circuit boards can be formed by milling cutter processing can be formed.

[0005] In addition, as a structure for positioning when fixing a printed circuit board to a chassis or the like, a recess is sometimes formed on the outer peripheral edge of the printed circuit board. When the boss for fixing the substrate provided on the chassis has a prismatic shape, a structure in which the bottom surface of the recess and the plane of the boss are in surface contact is required for positioning. Due to recent product miniaturization, the printed circuit board has also been miniaturized, and accordingly, the positioning recess has become narrow, and there is a need to form the positioning recess by milling cutter processing.

[0006] Figures 3 to 6 FIG. is an example of a conventional processing method for forming a recess 100 on the outer peripheral edge of a printed circuit board. Figure 3 A method of forming a recess only by milling cutter processing is shown. In Figure 3In the figure, the dashed arrow indicates the trajectory of the milling cutter RT. The milling cutter RT has a cylindrical shape, so the peripheral portion 102 of the bottom surface 101 of the recess 100 formed by cutting has a rounded corner, and the width becomes narrower as it approaches the bottom surface 101. Therefore, even if the width W of the boss 200 inserted into the recess 100 is smaller than the width W1 of the opening of the recess 100 O and larger than the width W1 of the straight portion of the bottom surface 101 B , the boss 200 cannot form a surface contact with the bottom surface 101 of the recess 100.

[0007] Figure 4 It also shows a method of forming the recess 110 only by milling cutter machining, but the trajectory of the milling cutter RT indicated by the dashed arrow is different from Figure 3 that. Figure 4 The trajectory of the milling cutter RT shown in (a) of has a shape close to the Latin letter "M", so the following machining method will be called "M-shaped machining". By performing M-shaped machining, only a flat bottom surface 111 is formed in the central portion of the recess 110, and at a position shallower than the bottom surface 111, there is no portion with a rounded corner whose width gradually becomes narrower. Thus, as shown in Figure 4 (b), without widening the width W1 of the opening of the recess 110 O , it is possible to make the plane of the boss 200 with a width W (W1 B < W < W1 O ) form a surface contact with the bottom surface 111 of the recess 110.

[0008] However, as shown in Figure 5 , when the opening width W2 of the recess 120 required corresponding to the width of the boss 200 is further narrowed (W1 O > W2 O > W2 O ), if only M-shaped machining is performed by the milling cutter RT, the bottom surface 121 of the recess 120 itself has a rounded corner and cannot form a flat surface, and it is impossible to make the plane of the boss 200 form a surface contact with the bottom surface 121 of the recess 120.

[0009] In contrast, Figure 6 shows a method of forming the recess 130 by performing M-shaped machining by combining long hole machining with a drill and milling cutter machining. Figure 6 (a) of shows a process of forming a long hole 132 with a drill DR having a diameter smaller than that of the milling cutter RT corresponding to a predetermined position where the recess 130 is to be formed. Figure 6The process shown in (b) is the process of forming the concave portion 130 by milling after the long hole machining. Before the milling operation, a long hole 132 is formed with a drill bit DR to a position deeper than the position of the bottom surface 131 that becomes the concave portion 130, so that when the milling cutter RT is used in the subsequent milling operation, there is no need to move the milling cutter RT with a larger diameter to a position deeper than the bottom 131.

[0010] By the processing method as Figure 6 shown, even in the case of forming the concave portion 130 with a narrow width W2 O , the bottom surface 131 can be formed as a flat surface, and the flat surface of the boss can be brought into surface contact with the bottom surface 131. However, when the milling cutter RT is moved along the Figure 6 dashed arrow trajectory in (b), as Figure 6 shown in (c), there is a problem of burrs 133 being generated at the peripheral portion on the rear side of the milling cutter trajectory on the bottom surface 131. This is because the milling operation has the property of moving the milling cutter RT in one direction like a single stroke, so that due to the burrs 133 generated during the long hole machining, there are portions that cannot be cut by the cutting edge of the milling cutter RT. When burrs 133 are generated, it is necessary to add a burr removal process, resulting in an increase in man-hours.

[0011] Prior art documents:

[0012] Patent documents:

[0013] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013-59818

[0014] Patent Document 2: Japanese Utility Model Publication No. 5-23564 Summary of the Invention

[0015] Problems to be solved by the invention:

[0016] The present invention is made to solve such problems, and its object is to be able to form a positioning flat surface on the bottom surface of the concave portion when forming a narrow concave portion on the outer peripheral edge portion of the printed circuit board, and also to be able to prevent the generation of burrs.

[0017] Means for solving the problems:

[0018] In order to solve the above-mentioned problems, in the present invention, a drill having a smaller diameter than a milling cutter is used to form a pre-hole in a region including a position deeper than the position of the bottom surface of the recessed portion in a first leg region corresponding to one leg of the M-shape, and then the milling cutter is moved along a substantially M-shaped trajectory from the first leg region side where the pre-hole is formed toward the second leg region side corresponding to the other leg of the M-shape, while cutting the outer peripheral edge portion of the printed circuit board, thereby forming the recessed portion. The substantially M-shaped trajectory is a trajectory in which the pre-hole formed in the first leg region is moved in a manner not to enlarge the pre-hole formed in the position deeper than the position of the bottom surface of the recessed portion, moves in a straight line in the bottom surface region between the first leg region and the second leg region, and moves to a position deeper than the position of the bottom surface of the recessed portion in the second leg region.

[0019] Effect of the invention:

[0020] According to the present invention constructed as described above, when a recess is formed in the outer peripheral edge of the printed circuit board by M-shaped processing, a pre-hole is formed using a drill having a smaller diameter than the milling cutter only in the first leg region corresponding to one leg of the M-shaped. Therefore, compared with the case where the milling cutter is used to dig deep to a position deeper than the position that becomes the bottom surface of the recess in the regions corresponding to both legs of the M-shaped, the distance between the deep-dug portion of the first leg region formed by the drill and the deep-dug portion of the second leg region formed by the milling cutter can be expanded. Therefore, even when a narrow recess is formed, a flat bottom surface can be formed in the central part of the recess (between the first leg region and the second leg region). In addition, according to the present invention, the pre-hole is formed only in the first leg region by drilling, so burrs are not generated in the second leg region due to drilling, and burrs generated in the first leg region due to drilling are removed in a manner that they are rolled into the milling cutter that moves from above the burrs. Therefore, according to the present invention, when a narrow recess is formed in the outer peripheral edge of the printed circuit board, a flat surface for positioning can be formed on the bottom surface of the recess, and burrs can also be prevented from being generated. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a diagram showing an example of a recessed portion formed in the outer peripheral edge portion of a printed wiring board by the substrate processing method according to the present embodiment.

[0022] Figure 2 It is a figure for demonstrating the substrate processing method involved in this embodiment.

[0023] Figure 3 It is a diagram showing an example of a conventional processing method for forming a recessed portion in the outer peripheral edge portion of a printed circuit board.

[0024] Figure 4 It is a diagram showing an example of a conventional processing method for forming a recessed portion in the outer peripheral edge portion of a printed circuit board.

[0025] Figure 5 This is a diagram showing an example of a conventional processing method for forming a recess in the outer peripheral portion of a printed circuit board.

[0026] Figure 6 This is a diagram showing an example of a conventional processing method for forming a recess in the outer peripheral portion of a printed circuit board.

[0027] Explanation of reference numerals:

[0028] 10 Recess

[0029] 11 Bottom surface

[0030] 12 Deeply dug portion in the first lead region

[0031] 13 Deeply dug portion in the second lead region

[0032] 20 Pilot hole

[0033] RT milling cutter

[0034] DR drill

[0035] Approximate M-shaped trajectory of the TK milling cutter Detailed implementation manner

[0036] Hereinafter, an embodiment of the present invention will be described based on the accompanying drawings. Figure 1 This is a diagram showing an example of a recess formed in the outer peripheral portion of a printed circuit board by the substrate processing method of this embodiment. As Figure 1 shown, in this embodiment, a narrow recess 10 having a planar bottom surface 11 at the center is formed. Narrow means that the opening width W2 of the recess O is small. According to this embodiment, by the milling cutter, in the recess 10 with an opening width W2 O of only about 3 mm, it is also possible to form a bottom surface 11 having a width W2 of about 0.8 mm B of.

[0037] Figure 2 This is a diagram for explaining the substrate processing method according to this embodiment, and is a diagram showing the processed portion of the printed circuit board on which the recess 10 is formed. Figure 2 (a) of Figure 2 shows the first process of the substrate processing method, Figure 2 (b) of

[0038] shows the second process. In Figure 2 (a) shown, the shape of the finally formed recess 10 is indicated by a dotted line. The drill bit), corresponding to a predetermined position where the recess 10 is formed, in the first leg region corresponding to one leg of the M shape, a pilot hole 20 is formed in a region including a position deeper than the position of the bottom surface 11 of the recess 10 (the deeply dug portion 12 of the first leg region). In the present embodiment, instead of performing pilot hole machining in the first leg region and the second leg region corresponding to the two legs of the M shape, the pilot hole 20 is formed only in the first leg region.

[0039] Here, by repeatedly performing a drilling process in which the drill bit DR moves vertically with respect to the printed circuit board while changing the position of the drill bit DR, a long hole-shaped pilot hole 20 is formed. The region including a position deeper than the position of the bottom surface 11 of the recess 10 means a region that satisfies the following condition: the rounded portion formed by drilling with a cylindrical drill bit DR becomes a position deeper than the bottom surface 11. The region where the pilot hole 20 is formed only needs to be a region that satisfies this condition. That is, the pilot hole 20 does not have to be a long hole shape and can also be a short hole shape.

[0040] In Figure 2 In the second process shown in (b) of, in the direction from the side of the first leg region where the pilot hole 20 is formed toward the side of the second leg region corresponding to the other leg of the M shape, the milling cutter RT cuts the outer peripheral edge portion of the printed circuit board while moving along a substantially M-shaped trajectory TK, thereby forming the recess 10. The trajectory TK of the milling cutter RT is preset to the milling machine, and the milling machine moves the milling cutter RT according to the set trajectory TK. The term "substantially M shape" instead of "M shape" means that the length of the portion corresponding to one leg of the M shape is not the same as the length of the portion corresponding to the other leg.

[0041] The substantially M-shaped trajectory TK is a trajectory that moves in the first leg region in a manner that does not expand the pilot hole 20 formed at a position deeper than the position of the bottom surface 11 of the recess 10, moves linearly in the bottom surface region between the first leg region and the second leg region, and moves to a position deeper than the position of the bottom surface 11 of the recess 10 in the second leg region. The milling cutter RT cuts the printed circuit board while moving along this series of trajectories TK, thereby forming the recess 10 having the shape shown in Figure 1 shown.

[0042] That is, in the first leg region, the milling cutter RT moves from the outer peripheral edge side of the printed circuit board toward the inside (from the opening side of the recess 10 toward the bottom surface side) along the pilot hole 20 to the middle, and then moves to the bottom surface region without digging the hole deeper than the position of the bottom surface 11 of the recess 10. As a result, the deeply dug portion 12 of the pilot hole 20 formed by the drill bit DR is substantially maintained as it is.

[0043] In the next bottom surface region, the milling cutter RT moves in a straight line. Thus, a planar bottom surface 11 is formed. In the present embodiment, a pilot hole 20 is formed by a drill bit DR having a diameter smaller than that of the milling cutter RT, and cutting is advanced into the bottom surface region while maintaining the pilot hole 20. Therefore, compared with the case where milling is performed on both legs of the M shape as in Figure 5 a longer distance can be ensured between the deepened portion 12a formed by the pilot hole 20 and the deepened portion 13 formed by milling in the next second leg region, and a planar bottom surface 11 can be formed here.

[0044] In the final second leg region, after the milling cutter RT moves to a position deeper than the position of the bottom surface 11 of the recess 10, it moves toward the outer peripheral edge portion of the printed circuit board. A position deeper than the position of the bottom surface 11 of the recess 10 means a region that satisfies the following condition: the rounded portion formed by cutting with the cylindrical milling cutter RT is deeper than the bottom surface 11.

[0045] The rotation direction of the milling cutter RT when moving along such a series of trajectories TK is the rotation direction in which the milling cutter RT presses the peripheral portion on the second leg region side of the bottom surface 11 when the milling cutter RT moves toward the outer peripheral edge portion (the opening portion of the recess 10) of the printed circuit board in the second leg region. In Figure 2 the case of (b) it is the clockwise direction. In this way, burrs can be prevented from being generated along with the milling process at the peripheral portion on the second leg region side of the bottom surface 11.

[0046] As described in detail above, in the present embodiment, when forming the recess 10 at the outer peripheral edge portion of the printed circuit board by M-shaped machining, only in the first leg region corresponding to one leg of the M shape, a pilot hole 20 is formed by a drill bit DR having a diameter smaller than that of the milling cutter RT. Thus, compared with the case where both regions corresponding to the two legs of the M shape are deepened by the milling cutter RT to a position deeper than the bottom surface position of the recess 120 as in Figure 5 the interval between the deepened portion 12a of the first leg region formed by the drill bit DR and the deepened portion 13 of the second leg region formed by the milling cutter RT can be widened.

[0047] Therefore, even when forming a narrow recess 10, a planar bottom surface 11 can be formed at the central portion (between the first leg region and the second leg region) of the recess 10. When forming the recess 10 having an opening width W2 using the drill bit DR and the milling cutter RT with an opening width W2 O = 3 mm, a planar bottom surface 11 with a width of 0.8 mm can be formed. In addition, even when forming a narrower opening width W2 OIn the case of the recessed portion 10 with a width of 2.8 mm, a flat bottom surface 11 with a width of 0.5 mm can be formed.

[0048] In addition, according to the present embodiment, the pre-hole 20 is formed only in the first leg region by drilling, so that burrs due to drilling are not generated in the second leg region. The burrs generated in the first leg region by drilling are removed in a manner that they are subsequently drawn into the milling cutter RT that moves from above the burrs. On the other hand, only milling is performed in the second leg region, so burrs are less likely to be generated compared to drilling. Moreover, by rotating the milling cutter RT in the direction of the peripheral portion of the second leg region side where the bottom surface 11 is pressed by the milling cutter RT, burrs generated accompanying milling can be reliably prevented.

[0049] Thus, by the substrate processing method of this embodiment, when a narrow recess is formed on the outer peripheral edge of the printed circuit board, a flat surface for positioning can be formed on the bottom surface of the recess, and burrs can also be prevented from being generated. In addition, the pre-hole processing only needs to be performed once, and there is no need for a burr removal process after milling, so the processing time and cost can be reduced.

[0050] In addition, in the above embodiment, an example is described in which the milling cutter RT is moved from the first leg region toward the second leg region to cut the printed circuit board after the pre-hole 20 is formed in the first leg region of the recess 10, but the opposite may be true. That is, after the pre-hole 20 is formed in the second leg region of the recess 10, the milling cutter RT is moved from the second leg region toward the first leg region to cut the printed circuit board. In this case, the rotation direction of the milling cutter RT is set to be counterclockwise.

[0051] In addition, the above-mentioned embodiments are only examples of specific implementations of the present invention, and should not be interpreted as limiting the technical scope of the present invention. That is, the present invention can be implemented in various forms without departing from its gist or its main features.

Claims

1. A substrate processing method, comprising forming a narrow recess having a planar bottom surface at the center on the outer peripheral portion of a printed circuit board, characterized in that comprising: a first step of forming a pilot hole in a first leg region corresponding to one leg of the M shape, in a region including a position deeper than the position of the bottom surface of the concave portion, using a drill bit having a diameter smaller than that of the milling cutter; and a second step of cutting the outer peripheral edge portion of the printed circuit board while moving the milling cutter along a substantially M-shaped trajectory in a direction from the side of the first leg region where the pilot hole is formed toward the side of a second leg region corresponding to the other leg of the M shape, thereby forming the concave portion, wherein the substantially M-shaped trajectory is a trajectory that moves in the first leg region in such a manner as not to expand the pilot hole formed at a position deeper than the position of the bottom surface of the concave portion, moves linearly in a bottom surface region between the first leg region and the second leg region, and moves to a position deeper than the position of the bottom surface of the concave portion in the second leg region.

2. The substrate processing method according to claim 1, wherein the rotation direction of the milling cutter is a rotation direction in which the milling cutter presses the peripheral portion of the bottom surface on the side of the second leg region when the milling cutter moves toward the outer peripheral edge portion of the printed circuit board in the second leg region.

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