JP2016063133A - Wiring board and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board that can ensure plating around a through hole, while suppressing the bending in the major axis direction, even when an elongated hole where the major axis is two time or more of the minor axis is formed, and the method of manufacturing the same.SOLUTION: In a wiring board including an insulating layer, a conductor circuit arranged on both sides of the insulating layer, a penetration hole penetrating the conductor circuit and the insulating layer, and a through hole having through hole plating on the inner wall of the penetration hole, the penetration hole is an elongated hole including a linear region in the major axis direction and circular arc regions at both ends of the linear region, in the plan view, and hole inner roughness of the inner wall of the circular arc region is smaller than that of the linear region.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wiring board having a long hole formed by a drill and a manufacturing method thereof.

  As electronic devices have higher functionality and higher density, the form of components mounted on the wiring board has also diversified. For example, in order to mount discrete components, etc., it is sometimes required to form long holes in the wiring board. is there. Here, the long hole means one having a linear region in the major axis direction and arc regions located at both ends of the linear region in plan view. For example, a plurality of through holes are linearly connected in the planar direction. And through holes provided continuously.

In order to improve the accuracy of the position of the long hole and the finished shape as a method of forming the long hole that is one of these irregular shaped through holes, the direction of drilling from the coordinate position corrected for the amount of deviation in the direction perpendicular to the long hole direction (Patent Document 1), a method of drilling holes using a drill having a tip angle θ of 150 ° ≦ θ ≦ 180 ° (Patent Document 2), and a method of opening a target slot after providing a pilot hole Has been proposed (Patent Documents 3 and 4).
JP 2009-124837 A JP 2003-071794 A Japanese Patent Laid-Open No. 10-041593 JP 2007-0985502 A

  However, Patent Documents 1 to 4 all improve the accuracy of the position and finished shape of the long hole in plan view, but the other important factors are the roughness of the inner wall of the hole and the long hole. It is not considered about the surroundings of the through-hole plating to be formed.

  Further, when forming a long slot whose major axis is twice or more the minor axis, the curvature of the straight region in plan view tends to increase as the length of the slot increases in the major axis direction. Further, as a method for suppressing this bending, a method of increasing the tip angle of the drill and making it easier to stabilize the drill during processing can be considered as in Patent Document 2 described above. Since the surface roughness of the entire inner wall is increased, the through hole plating may be insufficient when it is necessary to form a through hole.

  The present invention has been made in view of the above problems, and even when a long hole whose major axis is twice or more as long as the minor axis is formed, the bending of the major hole in the major axis direction is suppressed and through-hole plating is applied. Provided are a wiring board capable of securing the periphery and a manufacturing method thereof.

The inventor of the present invention has a tendency that a lack of contact with through-hole plating tends to occur in the arc region of the long hole, and the reason is that in the arc region of the long hole, the through-hole plating is performed as compared with the straight region. As a result of obtaining the knowledge that the liquid flow of the plating solution during the process tends to be insufficient, the present invention has been made. The present invention relates to the following.
(1) It has an insulating layer, a conductor circuit disposed on both surfaces of the insulating layer, a through hole penetrating the conductor circuit and the insulating layer, and a through hole having a through hole plating on the inner wall of the through hole. It is a wiring board, and the through hole is a long hole provided with a linear region in a major axis direction in plan view and an arc region located at both ends of the linear region, and the roughness in the hole of the inner wall of the arc region is A wiring board smaller than the roughness in the hole in the inner wall of the straight region.
(2) The wiring board according to item 1, wherein a long diameter of the long hole in plan view is twice or more a short diameter.
(3) A method for manufacturing a wiring board according to Item 1 or 2, wherein arc regions located at both ends of the elongated hole are formed with an undercut type round hole drill, and a straight line in the major axis direction of the elongated hole A method of manufacturing a wiring board, comprising: forming a region with a straight type long hole drill; and forming a through-hole plating on an inner wall of the long hole.
(4) In the item 3, in the step of forming the linear region in the major axis direction of the long hole with the long hole drill, the wiring board for forming the processed hole at a position that divides the interval between the formed holes into two equal parts. Production method.
(5) The method for manufacturing a wiring board according to item 3 or 4, wherein the hole pitch at which the center of the processed hole moves on the center line 14 is 0.07 to 0.22 mm.
(6) In any one of items 3 to 4, the tip angle α of the round hole drill is 130 ° or more and 150 ° or less, and the tip angle β of the long hole drill is 140 ° or more and less than 160 degrees. A method for manufacturing a wiring board.

  According to the present invention, even when a long hole whose major axis is twice or more of the minor axis is formed, a wiring board capable of securing the through hole plating while suppressing the bending of the long hole in the major axis direction and its A manufacturing method is provided.

It is a top view which shows a part of wiring board of one Embodiment of this invention. It is X-X 'sectional drawing of the wiring board of one Embodiment of this invention. It is Y-Y 'sectional drawing of the wiring board of one Embodiment of this invention. It is a top view which shows the formation method of the long hole of the wiring board of one Embodiment of this invention. The front-end | tip part of the long hole drill used for the manufacturing method of the wiring board of one Embodiment of this invention is shown. The tip part of the drill for round holes used for the manufacturing method of the wiring board of one Embodiment of this invention is shown.

(Wiring board)
An embodiment of a wiring board of the present invention will be described with reference to FIGS.
As shown in FIGS. 1 to 3, the wiring board 1 of the present embodiment includes an insulating layer 2, a conductor circuit 3 disposed on both surfaces of the insulating layer 2, and the conductor circuit 3 and the insulating layer 2. A wiring board 1 having a through-hole 4 and a through-hole 22 having a through-hole plating 7 on the inner wall 9 of the through-hole 4. The wiring board 1 is an elongated hole 8 having circular arc regions 6 positioned at both ends of the straight line region 5, and the inner wall 9 b of the circular arc region 6 has a smaller hole roughness than the inner wall 9 a of the straight line region 5. is there.

  In the present embodiment, the insulating layer 2 has electrical insulation and serves as a support for elements constituting the wiring substrate 1 such as the conductor circuit 3. It only needs to have electrical insulation and strength as a support, and can be formed using a general insulating material and method for a wiring board. From the viewpoint of high strength as a support, it is desirable to use a prepreg impregnated with a reinforcing material such as a glass cloth and impregnated with an epoxy resin or a polyimide resin and then molded using a hot press.

  The conductor circuit 3 is a conductor formed on the insulating layer 2 and patterned to form an electric circuit by electrically connecting electronic components or between an electronic component and a power source or a ground. A conductor circuit 3a and a land conductor circuit 3b are included. Similarly to a general wiring board, it can be formed by a circuit processing method such as a subtractive method or a semi-additive method using a metal foil such as a copper foil or plating.

  The through hole 4 is a hole provided so as to penetrate the conductor circuit 3 and the insulating layer 2 in order to form a long hole 8 described later, and is formed by drilling.

  2 and 3, the through hole plating 7 formed on the inner wall 9 of the through hole 4 is formed on the inner wall 9 of the through hole 4 in order to form the through hole 22. The through-hole plating 7 is formed in a film shape along the inner wall 9 of the through hole 4, and does not fill the through hole 4. For example, it is possible to form the through hole plating 7 on the inner wall 9 of the through hole 4 by using electroless copper plating, and then thicken it by using electrolytic copper plating.

  As shown in FIG. 1, the wiring board 1 of the present embodiment is a wiring board having a long hole 8 as a through hole 22, and is used for mounting discrete components and the like.

  As shown in FIG. 1, in the present embodiment, the through hole 4 is a long hole 8 that includes a linear region 5 in the major axis direction and arc regions 6 positioned at both ends of the linear region 5 in plan view.

  As shown in FIG. 1, the straight region 5 of the through hole 4 refers to a region where the outer periphery of the through hole 4 is formed so as to draw a straight line in the major axis direction in plan view. As a method of forming the straight region 5 in this way, as shown in FIG. 4, drilling is performed so that the hole center 13 of the circular processing hole 11 formed by drilling moves on the center line 14, And the method of arrange | positioning so that the adjacent process holes 11 may overlap is mentioned. Further, as the order and position of the drilling process, there is a method of forming the machining hole 11 at a position where the interval between the machining holes 10 and 11 that have already been formed is divided into two equal parts.

  In the present embodiment, the straight region 5 is provided at a right angle or parallel to the direction of a reinforcing fiber such as a glass cloth that is a reinforcing material. Thereby, since the inner wall 9a of the straight region 5 is formed at right angles or parallel to the direction of the reinforcing fiber such as glass cloth, the roughness in the hole tends to be smaller than the inner wall 9b of the arc region 6 described later. . On the other hand, the arc region 6 always has a portion that intersects at 45 degrees with respect to the direction of the reinforcing fiber such as a glass cloth, so that the roughness in the hole tends to be larger than the inner wall 9a of the straight region 5. However, in the present embodiment, as will be described later, by using a round hole drill for the arc region 6 and using a long hole drill for the straight region 5, the in-hole roughness of the inner wall 9b of the arc region 6 is reduced. A long hole smaller than the roughness in the hole of the inner wall 9a of the straight region 5 can be formed.

  The arc regions 6 positioned at both ends of the straight region 5 are regions where the outer periphery of the through hole 4 is formed so as to draw a substantially semicircle in plan view. The method of forming the arc region 6 in this manner is the same as that for forming the straight region 5, and as shown in FIG. 4, the hole center 13 of the circular processing hole 11 formed by drilling is the center line. The circular arc region 6 is formed at both ends of the linear region 5 by drilling so as to move on 14 and arranging the adjacent processing holes 11 so as to overlap each other to form the linear region 5.

  The long hole 8 in the present embodiment is an interlayer connection that electrically connects conductor circuits 3 of different layers, and a through hole 22 that is mainly used to insert and mount a lead such as a discrete component. It is the through hole 4 for forming.

  In the wiring board of the present embodiment, the in-hole roughness of the inner wall 9b of the arc region 6 (FIG. 3) is smaller than the in-hole roughness of the inner wall 9a of the linear region 5 (FIG. 2). The in-hole roughness (FIG. 3) of the inner wall 9b of the arc region 6 is preferably 40 μm or less, and more preferably 30 μm or less. Thereby, even if it is the environment where the circular arc area | region 6 was obstruct | occluded on one side, the circulation of a plating solution can be ensured and the surroundings of the through-hole plating 7 can be ensured. Further, the roughness in the hole (FIG. 2) of the inner wall 9a of the linear region 5 is preferably 60 μm or less, more preferably 50 μm or less. If it is the range of this roughness in a hole, the surroundings of the through-hole plating 7 can be ensured because the straight region 5 is an open environment.

  As shown in FIG. 1, since the straight region 5 is located in a region that is not at both ends of the long hole 8, there is a space of the arc region 6 on both sides and is open, so when forming the through-hole plating 7 The plating solution is easy to circulate. For this reason, even if the inner wall 9a is somewhat rough in the hole, the through hole plating 7 can be secured. Here, in the drilling process in the straight region 5, as shown in FIG. 4 (process B-1) and (process B-2), a part that has already been processed and the processed hole 10 is formed and an unprocessed part are divided. Since the drilling process may occur over the span, the load on the drill is biased, and as a result, the straight region 5 tends to bend in the vertical direction from the major axis direction in plan view. However, in the straight region 5, the inner wall 9 a may have a slightly rough inner hole, so that in the straight region 5, which tends to bend in a plan view, a long hole drill with good straightness is obtained although the inner roughness is large. Can be used.

  Moreover, in FIG. 4 (process B-1) and (process B-2), the space | interval of the already formed process holes 10 and 11 is divided into two equally according to the order of the drill process shown near the hole center 13. FIG. By forming the processed hole 11 at the position, even when drilling occurs across the part that has already been processed and the processed hole 10 is formed and the unprocessed part, drilling is performed in the major axis direction of the long hole 8. Since the load balance can be maintained, bending can be suppressed. Furthermore, by repeating FIG. 4 (process B-1) and (process B-2), as shown in FIG. 4 (B-3), the inner wall 9a of the straight region 5 becomes substantially straight in plan view. Can be.

  On the other hand, as shown in FIG. 1, since the arc region 6 is located at both ends of the long hole 8, one side is closed, and it is difficult for the plating solution to circulate when forming the through-hole plating 7. For this reason, when the inner wall 9b is rough in the hole, there is a possibility that the through hole plating 7 cannot be secured. However, for example, as shown in FIG. 4 (step A), by drilling the holes at both ends that will be the arc region 6 of the long hole 8 first, the drilling is performed only on the unprocessed portion. Become. For this reason, the arc region 6 is different from the straight region 5 in that there is no problem of bending in a plan view. Therefore, it is possible to use a round hole drill with inferior straightness but small in-hole roughness.

  In this way, since the in-hole roughness of the inner wall 9b of the arc region 6 is smaller than the in-hole roughness of the inner wall 9a of the straight region 5, in the straight region 5, the bending of the long hole 8 in the major axis direction is suppressed and the through hole is suppressed. The area around the plating 7 can be secured, and the area around the through-hole plating 7 can be secured even in the arc region 6. Therefore, it is possible to provide a wiring board capable of securing the through hole plating 7 while suppressing the bending of the long hole in the long diameter direction even when forming a long long hole whose long diameter is twice or more the short diameter.

  The long hole drill refers to a drill that does not easily bend. For example, as shown in FIG. 5, the diameter of the long hole drill 20 is the same from the blade tip to the root and has no undercut. Is mentioned. Thus, since the rigidity of the drill of the straight type drill is high, the bending of the long hole 8 in the major axis direction can be suppressed.

  On the other hand, the round hole drill refers to a drill in which the inner roughness of the inner wall 9 of the through hole 4 is smaller than the inner roughness of the inner wall 9 of the through hole 4 formed by the long hole drill. As shown, an undercut type drill having an undercut 18 with respect to the diameter 16 of the blade 15 of the round hole drill may be mentioned. Here, the undercut means a dimension in which the diameter on the base side of the cutting edge is smaller than the diameter of the cutting edge of the drill, and this undercut is generally 0.01 to 0.05 mm. In the undercut type drill, the friction with the inner wall 9 of the hole is reduced as compared with the straight type drill, and the roughness can be reduced.

  In this Embodiment, as shown in FIG. 1, it is preferable that the long diameter in planar view of a long hole is 2 times or more of a short diameter. As a result, since the plating solution circulates in the straight region 5 of the long hole, even if the inner wall 9a is rough to some extent, the through hole plating 7 can be secured, and the arc region 6 can be seen in a plan view. Straight lines are not a problem, and drilling is possible using a round hole drill having a small inner roughness of the inner wall 9b.

(Method for manufacturing a wiring board)
One embodiment of a method for manufacturing a wiring board according to the present invention will be described with reference to FIGS.
As shown in FIG. 4, the manufacturing method of the wiring board 1 according to the present embodiment includes a step A in which arc regions 6 located at both ends of the elongated hole 8 are formed by an undercut type round hole drill, and the long Step B (steps B-1 to B-3) of forming the straight region 5 in the major axis direction of the hole 8 with a straight type long hole drill, and step C of forming the through-hole plating 7 on the inner wall 9 of the slot 8 (Not shown).

  First, as shown in FIG. 4 (process A), in the process A in which the arc regions 6 positioned at both ends of the long hole 8 are formed by an undercut type round hole drill, only an unprocessed portion is drilled. Therefore, the load on the drill is the same in all directions, and bending is difficult to occur. For this reason, an undercut type drill for round holes can be used. Further, since the undercut type round hole drill in the arc region 6 is used, the in-hole roughness of the inner wall 9b of the arc region 6 can be kept small. The numbers near the hole center 13 indicate the order of drilling.

  Next, as shown in FIG. 4 (process B-1) to (process B-3), in the process B in which the straight region 5 in the major axis direction of the long hole 8 is formed with a straight type long hole drill, drilling is performed. Drilling is performed so that the hole center 13 of the formed circular processing hole 11 moves on the center line 14, and the adjacent processing holes 11 are arranged so as to overlap each other. The numbers near the hole center 13 indicate the order of drilling. As shown in FIG. 4 (process B-1) and (process B-2), drilling is performed across the unprocessed part and the part that has already been processed and the processed hole 10 is formed. There is a tendency for the load to be uneven and to bend easily. However, in the straight region 5, even if the inner wall 9a is somewhat rough, the through-hole plating 7 is good, so that it is possible to use a long hole drill with good straightness although the hole roughness increases. Become. Therefore, the bending of the long hole 8 in the major axis direction can be suppressed.

  Next, in the process C (not shown) of forming the through-hole plating 7 on the inner wall 9 of the long hole 8, the open area in which the plating solution is easy to circulate in the straight region 5 although the inner wall 9 a has a large roughness in the hole. Therefore, the circulation of the plating solution is ensured, and the attachment of the through-hole plating 7 is ensured. Further, the arc region 6 is a closed environment in which the plating solution is difficult to circulate, but the inner wall 9b has a small hole roughness, so that the circulation of the plating solution is secured and the through hole plating 7 is secured. Therefore, the attachment of the through-hole plating 7 is ensured over the entire long hole 8. The through-hole plating 7 can be formed, for example, by forming an underlying power supply layer on the inner wall 9 of the through-hole 4 using electroless copper plating and then thickening using electroless copper plating. .

  As shown in FIG. 4 (process B-1) and (process B-2), in the present embodiment, in the process of forming the linear region 5 in the major axis direction of the long hole 8 with a long hole drill, it is already formed. It is preferable to form the processed holes 11 at positions that divide the interval between the processed holes 10 and 11 into two equal parts. Thereby, as shown to FIG. 4 (process B-1), it can drill only to the area | region where drilling is not processed as much as possible, and since the load in the rotation direction of a drill becomes equal, bending can be suppressed. Moreover, as shown to FIG. 4 (process B-1) and (process B-2), the case where the case where it drills across the part which has already been processed and the processed hole 10 is formed, and an unprocessed part arises. However, since the load balance of the drill can be maintained in the major axis direction of the long hole 8, the bending can be suppressed. Therefore, bending can be suppressed over the entire major axis direction of the long hole 8. Furthermore, by repeating FIG. 4 (process B-1) and (process B-2), as shown in FIG. 4 (B-3), the inner wall 9a of the straight region 5 becomes substantially straight in plan view. Can be.

  4 (step B-1) to (step B-3), the hole pitch 12 at which the hole center 13 moves on the center line 14 is preferably 0.07 to 0.22 mm for each drilling of one hole. . By setting the hole pitch 12 in this range, the straight line region 5 in plan view shown in FIG. 1 is closer to a straight line, and the roughness in the hole of the inner wall 9a of the straight line region shown in FIG. 2 is reduced. For this reason, the surroundings of the through-hole plating 7 can be ensured.

  In the present embodiment, it is preferable that the tip angle α of the round hole drill is 130 ° or more and 150 ° or less in that a processed hole with small in-hole roughness can be formed. It is preferable that the tip angle β of the long hole drill is 140 ° or more and less than 160 ° in that the straightness of the drill can be improved and bending can be suppressed.

(Example)
First, a copper-clad laminate (Hitachi Chemical Co., Ltd., trade name MCL-E-679, thickness 1.6 mm) having copper foil with a thickness of 18 μm on both sides of an insulating layer impregnated with glass cloth with epoxy resin. The conductor circuit was formed in both surfaces by preparing and etching copper foil.

  Next, an upper cover plate was disposed on the drill entry surface of the wiring board, and a phenol resin substrate undercoat plate was disposed on the surface opposite to the drill entry surface. Thus, the wiring board was fixed and sandwiched between the upper plate and the lower plate of the phenol resin substrate, and set on the drilling table of the NC control drilling machine (trade name MARK20, manufactured by Hitachi Via Mechanics Co., Ltd.). .

Next, as shown in FIG. 4 (step A), the arc regions 6 positioned at both ends of the long hole 8 were formed with an undercut type round hole drill. Here, NC control drilling was performed using an undercut type drill (trade name 128 9110, manufactured by Union Tool Co., Ltd.) with a drill blade length of 9.0 mm, a diameter of 1.1 mm, and a tip angle of 140 degrees. The machined hole 10 was formed with a machine (manufactured by Hitachi Via Mechanics Co., Ltd., trade name MARK20) under the conditions of a spindle rotation speed of 55,000 min ⁻¹ and a feed rate of 1.40 m / min. The distance between the hole centers 13 of the processed holes 10 is 3.0 mm. The numbers near the hole center 13 indicate the order of drilling.

Next, as shown to FIG. 4 (process B-1)-(process B-3), the linear area | region 5 of the long diameter direction of the long hole 8 was formed with the drill for straight type long holes. Here, using a straight type drill with a drill length of 8.7 mm, a diameter of 1.1 mm, and a tip angle of 150 degrees (CARBIDE INTERNATIONAL, trade name: TCT SD24 SD 1100), the spindle rotation speed is 50, The machining hole 11 was formed under the drilling conditions of 000 min ⁻¹ and a feed rate of 2.5 m / min. The numbers near the hole center 13 indicate the order of drilling.

  As shown in FIG. 4 (process B-1) and (process B-2), in the present embodiment, in the process of forming the linear region 5 in the major axis direction of the long hole 8 with a long hole drill, it is already formed. The processed holes 11 were formed at positions where the interval between the processed holes 10 and 11 was equally divided. Further, FIG. 4 (Step B-1) and (Step B-2) are repeated, and finally, the hole pitch 12 at which the hole center 13 moves on the center line 14 is set to about 0.1 mm. As shown to (B-3), the inner wall 9a of the linear area | region 5 formed the substantially straight long hole 8 by planar view.

  Next, the through-hole plating 7 was formed in the inner wall 9 of the long hole 8 (process C). In addition, the inside of the long hole 8 after drilling is only spray-washed, and the desmear process using permanganic acid etc. which are used with a multilayer wiring board is not performed. The through-hole plating 7 uses CUST2000 (trade name, manufactured by Hitachi Chemical Co., Ltd., “CUST” is a registered trademark), which is an electroless copper plating for thinning, and has a thickness of about 1 μm on the inner wall 9 of the through-hole 4. After forming the base power feeding layer, the thickness was about 25 μm by electrolytic copper plating using a copper sulfate plating bath.

(Comparative Example 1)
In FIG. 4 (Process A), the arc regions 6 positioned at both ends of the long hole 8 are formed by a straight type long hole drill instead of being formed by an undercut type round hole drill. In the same manner, the long hole 8 was formed.

(Comparative Example 2)
In FIG. 4 (process B-1) to (process B-3), a long region is formed in the same manner as in the embodiment except that the straight region 5 in the major axis direction of the long hole 8 is formed by an undercut type round hole drill. Hole 8 was formed.

(Linearity linearity)
From the front and back sides of the wiring board after through-hole plating, the level (within 0.1 mm) where the bending could not be visually confirmed was ○, and the level (over 0.1 mm) that could be visually confirmed was x.

(Measurement of hole inner wall roughness)
10 holes each are cast from the wiring board after through-hole plating, and the cross section of the inner wall 9 of the long hole 8 is observed with a magnification of 500 times using a metal microscope, and the roughness in the hole (the uneven step on the inner wall of the hole) Was measured. At this time, with respect to the linear region 5 in the major axis direction of the long hole 8, a cross section in a direction perpendicular to the major axis direction (XX ′ direction in FIG. 1, parallel to the fiber of the glass cloth) is observed. For the arc region 6, a cross section in the major axis direction (YY ′ direction in FIG. 1, parallel to the fiber of the glass cloth) was observed. In addition, for the arc region 6 of the long hole 8, a direction intersecting with the major axis direction (YY ′ direction in FIG. 1, a direction parallel to the fiber of the glass cloth) at 45 degrees (a direction intersecting with the fiber of the glass cloth at 45 degrees). The cross section was also observed. In addition, regarding the in-hole roughness of each hole, the maximum roughness in the hole was defined as the in-hole roughness of the hole, and the maximum value, minimum value, and average value of the in-hole roughness for each 10 holes were calculated.

(Around through hole plating)
Ten holes were cast from the wiring board after through-hole plating, and the cross section of the inner wall 9 of the long hole 8 was observed and evaluated at a magnification of 100 times using a metal microscope. When the thickness of the through-hole plating on the inner wall in the hole is 50% or more with respect to the plating thickness of the surface of the wiring board, △ is indicated when the thickness is less than 50%, and the through-hole plating is not observed. When it was, it was set as x.

(Evaluation results)
Table 1 shows the measurement results (minimum value to maximum value) of the in-hole roughness of Examples and Comparative Examples 1 and 2 and the evaluation results of the attachment of through-hole plating.

In the example, although the roughness in the hole of the linear region was larger than that of the arc region, the linearity of the plating area and the linear region was good. In Comparative Example 1 using only the straight type long hole drill, the roughness in the hole in the arc region was large, and the periphery with plating could not be obtained. In Comparative Example 2 using only the undercut type round hole drill, bending or drill breakage occurred in the linear region, and linearity was not obtained. In Comparative Examples 1 and 2, although the same drill is used, the straight area has a smaller hole roughness than the arc area because the hole pitch of the processed holes is small. Most of the parts are already finished, and what is actually drilled is a very small part, which is thought to be because the load on the drill is small. On the other hand, in the arc region, it is considered that an unprocessed portion is processed and the load on the drill is large.

1. 1. Wiring board 2. Insulating layer Conductor circuit 3a. (Line-shaped) conductor circuit 3b. 3. (land-shaped) conductor circuit Through hole 5. 5. Linear area Arc region 7. Through-hole plating8. Slot 8a. Minor axis 8b. Major axis 9. Inner wall 9a. Inner wall 9b. Inner wall (in the arc region) 10. Processing hole (for round hole drill) 11. Processing hole (for long hole drills) 12. Hole pitch13. Hole center 14. Center line 15. Round hole drill blade 16. Diameter (of drill blade) 17. Undercut diameter 18. Undercut 19. Tip angle α
20. 21. Long hole drill blade 21. Tip angle β
22. Through hole 23. Land 24. Copper foil

Claims (6)

  A wiring board having an insulating layer, a conductor circuit disposed on both surfaces of the insulating layer, a through hole penetrating the conductor circuit and the insulating layer, and a through hole having a through hole plating on an inner wall of the through hole. The through hole is a long hole having a linear region in the major axis direction in plan view and an arc region located at both ends of the linear region, and the roughness in the hole of the inner wall of the arc region is A wiring board smaller than the roughness in the hole in the inner wall.   2. The wiring board according to claim 1, wherein the major axis of the elongated hole in plan view is twice or more the minor axis.   It is a manufacturing method of the wiring board of Claim 1 or 2, Comprising: The process of forming the circular arc area | region located in the both ends of the said long hole with an undercut type round hole drill, and the linear area | region of the long diameter direction of the said long hole A method of manufacturing a wiring board, comprising: a step of forming with a straight type long hole drill; and a step of forming through-hole plating on an inner wall of the long hole.   4. The method for manufacturing a wiring board according to claim 3, wherein in the step of forming the straight region in the major axis direction of the elongated hole with the elongated hole drill, the processed hole is formed at a position that divides the interval between the formed holes into two equal parts. .   5. The method of manufacturing a wiring board according to claim 3, wherein a hole pitch at which the center of the processed hole moves on the center line 14 is 0.07 to 0.22 mm.   5. The wiring according to claim 3, wherein the tip angle α of the round hole drill is 130 ° or more and 150 ° or less, and the tip angle β of the long hole drill is 140 ° or more and less than 160 °. A method for manufacturing a substrate.

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