WO2021200820A1

WO2021200820A1 - Printed wiring board and method for manufacturing same

Info

Publication number: WO2021200820A1
Application number: PCT/JP2021/013285
Authority: WO
Inventors: 啓作松本
Original assignee: 京セラ株式会社
Priority date: 2020-03-30
Filing date: 2021-03-29
Publication date: 2021-10-07
Also published as: JPWO2021200820A1

Abstract

This printed wiring board comprises an insulating substrate 1 and a conductor portion 3 disposed at least inside the insulating substrate 1. The insulating substrate 1 has a plurality of stacked insulating layers. The insulating substrate 1 has a through-hole 7 penetrating therethrough from a first opening thereof to a second opening thereof in the thickness direction. The conductor portion 3 includes a plurality of conductor layers 9 and a through-hole conductor 11. The plurality of conductor layers 9 are respectively positioned along the insulating layers 5 in a planar direction. The through-hole conductor 11 has a tubular shape extending from the first opening toward the second opening. The through-hole conductor 11 at an existing position is electrically connected to some of the plurality of conductor layers 9. The plurality of conductor layers 9 include at least one layer of a non-connected conductor layer closer to the second opening than to the through-hole conductor 11 which is not in contact with the through-hole conductor 11. The through-hole conductor 11, in a cross-sectional view taken along the central axis of the through-hole 7, has two end portions closer to the second opening, including a first end portion and a second end portion that have different positions in the thickness direction.

Description

Printed wiring board and its manufacturing method

This disclosure relates to a printed wiring board and a method for manufacturing the printed wiring board.

In recent years, printed wiring boards have been required to have high density mounting and thinning due to higher functionality and higher performance of electronic devices (see, for example, Japanese Patent Application Laid-Open No. 2017-135357).

The printed wiring board of the present disclosure has an insulating substrate and a conductor portion arranged at least inside the insulating substrate. The insulating substrate has a plurality of laminated insulating layers and through holes penetrating from the first opening to the second opening in the thickness direction. The conductor portion has a plurality of conductor layers and a through-hole conductor. The plurality of conductor layers are located along the plane direction in each of the insulating layers. The through-hole conductor has a cylindrical shape extending from the first opening toward the second opening. The through-hole conductor is electrically connected to a part of the plurality of conductor layers at the existing position. The plurality of conductor layers have at least one non-connecting conductor layer that is not in contact with the through-hole conductor near the second opening of the through-hole conductor. The through-hole conductors have different positions in the thickness direction of the first end portion and the second end portion, which are two end portions close to the second opening, in a cross-sectional view along the central axis of the through hole.

The printed wiring board of the present disclosure has an insulating substrate and a conductor portion arranged at least inside the insulating substrate. The insulating substrate has a plurality of laminated insulating layers and through holes penetrating from the first opening to the second opening in the thickness direction. The conductor portion has a plurality of conductor layers and a through-hole conductor. The plurality of conductor layers are located along the plane direction in each of the insulating layers. The through-hole conductor has a cylindrical shape extending from the first opening toward the second opening. The through-hole conductor is electrically connected to a part of the plurality of conductor layers at the existing position. The plurality of conductor layers have at least one non-connecting conductor layer that is not in contact with the through-hole conductor near the second opening of the through-hole conductor. The end face of the through-hole conductor near the second opening is inclined with respect to the central axis of the through-hole.

The method for manufacturing a printed wiring board of the present disclosure includes an insulating substrate in which a plurality of insulating layers are laminated, a conductor layer provided along the surface of the insulating layer, and a through hole penetrating the insulating substrate in the thickness direction. Including a step of preparing a multilayer substrate having a copper through-hole conductor original body covering the inner wall of the material. The manufacturing method includes a step of forming a protective layer which is not dissolved by the copper etching solution on the entire inner wall of the through-hole conductor raw material provided on the multilayer substrate. The manufacturing method uses a cutting jig having a diameter larger than the inner diameter of the through-hole conductor original body and having a tapered tip portion, and the axial center of the through hole is the through hole. The through-hole conductor original body and the protective layer are cut from one surface side of the multilayer substrate to a position in the middle of the thickness direction of the multilayer substrate by arranging the through-hole conductor original body and the protective layer at a position deviated from the central axis of the multilayer substrate. The step of making the through-hole conductor original body electrically connected to at least two conductor layers is included.

It is sectional drawing which shows a part of the printed wiring board shown as an example of embodiment. It is a schematic diagram which shows the other aspect of the through-hole conductor in the printed wiring board of an embodiment. It is sectional drawing which shows the other aspect of the printed wiring board of an embodiment. It is sectional drawing of the multilayer substrate used in the manufacturing method of the printed wiring board of an embodiment. It is sectional drawing which shows the printed wiring board processed body which formed the protective layer on the multilayer board shown in FIG. FIG. 5 is a cross-sectional view showing a state in which a portion of a through-hole conductor bulk material provided in the printed wiring board processed body shown in FIG. 5 is machined. It is sectional drawing which shows the state of the printed wiring board processed body after partially cutting a through-hole conductor raw material. FIG. 5 is a cross-sectional view showing a state after etching the printed wiring board processed body shown in FIG. 7. It is sectional drawing which shows the state after removing the protective layer from the printed wiring board processed body shown in FIG. It shows the manufacturing method of the printed wiring board of another aspect, and is sectional drawing which shows the state which cuts the part of the through-hole conductor original body with respect to the printed wiring board processed body which formed the protective layer. It is sectional drawing which shows the state of the printed wiring board processed body after partially cutting a through-hole conductor raw material. It is sectional drawing which shows the state after performing the etching process on the printed wiring board processed body shown in FIG. It is sectional drawing which shows the state after removing the protective layer from the printed wiring board processed body shown in FIG. It is a top view of the produced printed wiring board.

As described above, the printed wiring board disclosed in Patent Document 1 is required to have the ability to mount electric elements at a high density in order to realize high functionality and high performance of electronic devices. When mounting a plurality of electric elements on a printed wiring board, it is necessary to design the wiring according to each electric element. Impedance matching of printed wiring boards is difficult due to the high density of wiring.

FIG. 1 is a cross-sectional view showing a part of a printed wiring board shown as an example of an embodiment. The printed wiring board A of the embodiment has an insulating substrate 1 and a conductor portion 3 arranged at least inside the insulating substrate 1. The insulating substrate 1 has a structure in which a plurality of insulating layers 5 are laminated. Here, for convenience, each insulating layer 5 is designated by a different reference numeral. The insulating substrate 1 has a structure in which a first insulating layer 5a, a second insulating layer 5b, and a third insulating layer 5c are laminated from an upper layer. FIG. 1 shows a case where the insulating layer 5 has three layers, but the present invention is not limited to this. The insulating substrate 1 also includes those having more than three insulating layers 5. The number of layers of the insulating layer 5 constituting the insulating substrate 1 may be 3 or more. For example, in the case of a structure in which the printed wiring board has an antenna, a filter, and the like, the number of layers is 30 or more. The upper limit of the number of layers of the insulating layer 5 is not particularly set, but 50 layers or less may be used as a guide.

Further, the insulating substrate 1 has a through hole 7. The through hole 7 penetrates the insulating substrate 1 in the thickness direction. The through hole 7 has a first opening 8a on one surface side of the insulating substrate 1. The other surface side of the insulating substrate 1 is the second opening 8b. The first opening 8a and the second opening 8b are arranged so as to face each other in the insulating substrate 1. Further, in the vertical cross-sectional view of the printed wiring board A shown in FIG. 1, for convenience, the inner wall on the left side of the through hole 7 is designated by reference numeral 7L, and the inner wall on the right side of the through hole 7 is designated by reference numeral 7R.

In FIG. 1, reference numeral 3 representing the conductor portion is used as a code for grouping the conductor layers 9 (9a, 9b, 9c, 9d, 9e, 9f, 9g, 9h) and the through-hole conductor 11. The conductor portion 3 has a plurality of conductor layers 9 and a through-hole conductor 11. The plurality of conductor layers 9 are located along the plane direction of each of the insulating layers 5. In FIG. 1, for convenience, the names and symbols of the conductor layers 9 arranged in each layer are changed. This is to make it possible to distinguish the conductor layers 9 arranged in each layer of the insulating layer 5 in FIG. The arrangement of each conductor layer 9 is shown in FIG. In the vertical cross-sectional view of the printed wiring board A, the first conductor layer 9a, the second conductor layer 9b, the third conductor layer 9c, and the third conductor layer 9c are arranged on the left side via the insulating layer 5, respectively, from the upper side in the stacking direction. A four-conductor layer 9d is arranged. On the right side, the fifth conductor layer 9e, the sixth conductor layer 9f, the seventh conductor layer 9g, and the eighth conductor layer 9h are arranged from the upper side in the stacking direction via the insulating layer 5, respectively. In this case, the first conductor layer 9a and the fifth conductor layer 9e arranged on the left side and the right side of one insulating layer (for example, the first insulating layer 5a) are electrically connected. Notation of 1st conductor layer 9a, 2nd conductor layer 9b, 3rd conductor layer 9c, 4th conductor layer 9d, 5th conductor layer 9e, 6th conductor layer 9f, 7th conductor layer 9g and 8th conductor layer 9h. Is used for convenience when the printed wiring board A is viewed in the vertical sectional view shown in FIG.

In FIG. 1, reference numeral 11 representing a through-hole conductor is a reference numeral that combines reference numeral 11L and reference numeral 11R. The through-hole conductor 11 has a cylindrical shape. The through-hole conductor 11 extends from the first opening 8a toward the second opening 8b. On the contrary, the through-hole conductor 11 extends from the second opening 8b side in the direction of the first opening 8a. In the vertical cross-sectional view of FIG. 1, the through-hole conductor 11 in contact with the inner wall 7L of the through-hole 7 is the first through-hole conductor 11L. The through-hole conductor 11 in contact with the inner wall 7R of the through-hole 7 is the second through-hole conductor 11R. The first through-hole conductor 11L and the second through-hole conductor 11R are used for convenience when the printed wiring board A is viewed based on a vertical cross-sectional view as shown in FIG. The through-hole conductor 11 has a first through-hole conductor 11L and a second through-hole conductor 11R. In this case, the first through-hole conductor 11L and the second through-hole conductor 11R are electrically connected. The via hole conductor 11 may be arranged so that one via hole conductor 11 is vertically divided, and the two are separately insulated and arranged.

The through-hole conductor 11 has an end portion 11t in the middle of the insulating substrate 1 in the thickness direction. In the vertical cross-sectional view of FIG. 1, the end portion of the first through-hole conductor 11L located on the left side of the through-hole conductor 11 is designated by reference numeral 11 tL. In the vertical cross-sectional view of FIG. 1, the end portion of the second through-hole conductor 11R located on the right side of the through-hole conductor 11 is designated by reference numeral 11 tR. Here, reference numeral 11t is used when the reference numeral 11tL at the end of the first through-hole conductor 11L and the reference numeral 11tR at the end located on the right side of the second through-hole conductor 11 are collectively indicated. The through-hole conductor 11 reaches the surface 1a of the insulating substrate 1 on the surface 1a side of one side of the insulating substrate 1. The through-hole conductor 11 does not reach the front surface (back surface) 1b of the insulating substrate 1 on the other side surface 1b side of the insulating substrate 1. Here, the surface 1a on one side of the insulating substrate 1 is positioned on the upper surface side (first opening 8a side) of the insulating substrate 1 in FIG. The front surface (back surface) 1b on the other side of the insulating substrate 1 is positioned on the lower surface side (second opening 8b side) of the insulating substrate 1 in FIG. In the present disclosure, the through-hole conductor 11 may reach the surface 1b on the lower surface side of the insulating substrate 1 and may not reach the surface 1a on the upper surface side. The through-hole conductor 11 is provided so as to partially cover the inner wall 7L and the inner wall 7R of the through-hole 7 in the thickness direction. The through-hole conductor 11 is electrically connected to a plurality of conductor layers at a position where the through-hole conductor 11 exists.

The plurality of conductor layers 9 have at least one non-connecting conductor layer that is not in contact with the through-hole conductor 11 closer to the second opening 8b than the through-hole conductor 11. The first through-hole conductor 11L excludes at least one conductor layer 9 from the plurality of conductor layers (first conductor layer 9a, second conductor layer 9b, third conductor layer 9c, and fourth conductor layer 9d). It is electrically connected to another conductor layer 9. In this case, the first through-hole conductor 11L is electrically connected to the first conductor layer 9a and the second conductor layer 9b. The first through-hole conductor 11L is not connected to the third conductor layer 9c and the fourth conductor layer 9d. The through-hole conductor 11 is the other conductor layer 9 except for at least one of the plurality of conductor layers (fifth conductor layer 9e, sixth conductor layer 9f, seventh conductor layer 9g, and eighth conductor layer 9h). It is electrically connected to the conductor layer 9. In this case, the second through-hole conductor 11R is electrically connected to the fifth conductor layer 9e and the sixth conductor layer 9f. The second through-hole conductor 11R is not connected to the seventh conductor layer 9g and the eighth conductor layer 9h. In this case, the conductor layer 9 excluding at least one conductor layer 9 is the third conductor layer 9c, the fourth conductor layer 9d, the seventh conductor layer 9g, and the eighth conductor layer 9h. Here, the non-connecting conductor layer refers to the third conductor layer 9c, the fourth conductor layer 9d, the seventh conductor layer 9g, and the eighth conductor layer 9h.

The position of the end portion 11t of the through-hole conductor 11 in the thickness direction is different between the

inner walls

7L and 7R of the through-hole 7 when the insulating substrate 1 is viewed in a vertical cross section. In other words, the end portion 11tL of the first through-hole conductor 11L and the end portion 11tR of the second through-hole conductor 11R are located between the

inner walls

7L and 7R of the through-hole 7 when the insulating substrate 1 is viewed in a vertical cross section. The position in the thickness direction is different. The end portion 11tL of the first through-hole conductor 11L is hereinafter referred to as the first end portion 11tL. The end portion 11tR of the second through-hole conductor 11R is hereinafter referred to as the second end portion 11tR. The through-hole conductor 11 has different positions of the first end portion 11tL and the second end portion 11tR, which are two end portions close to the second opening 8b, in a cross-sectional view along the central axis Z of the through hole 7.

In FIG. 1, the central axis Z is shown separately on the upper side and the lower side of the printed wiring board A, but if it is described in the through hole 7, it may overlap with the display of other symbols or the like. This is because it came. The central axis Z is linearly connected to the upper side and the lower side of the printed wiring board A.

The fact that the positions of the first end portion 11tL and the second end portion 11tR are different is evaluated from the shape of the through-hole conductor 11 seen when the printed wiring board A or the insulating substrate 1 is viewed in cross section. That is, in the printed wiring board A shown in FIG. 1, the length LL of the first through-hole conductor 11L is longer than the length LR of the second through-hole conductor 11R. In other words, in the printed wiring board A shown in FIG. 1, the end portion 11tL of the first through-hole conductor 11L is located at a position deeper than the end portion 11tR of the second through-hole conductor 11R. That is, the printed wiring board A has a dimensional difference ΔL between the length LL of the first through-hole conductor 11L and the length LR of the second through-hole conductor 11R. Here, the dimensional difference ΔL is the difference in length between the length LL of the first through-hole conductor 11L and the length LR of the second through-hole conductor 11R. ΔL may have a different capacitance component that contributes to impedance in the printed wiring board A. ΔL depends on the thickness of the insulating layer 5 (here, the second insulating layer 5b), but may be 1 μm or more. The maximum value of ΔL is not particularly provided, but it may be within twice the thickness t of the one-layer insulating layer 5, and in particular, within a length corresponding to the thickness of the one-layer insulating layer 5. For example, it is preferably within 100 μm, particularly within 50 μm.

The printed wiring board A shown in FIG. 1 has different lengths of facing portions of the through-hole conductors 11 arranged in the through-hole 7 in this way. In this case, the opposing portions in the through-hole 7 are portions arranged on both sides when the through-hole conductor 11 is vertically divided, as shown in FIG. When the cross section of the through-hole conductor 11 has a cylindrical shape, the cross section is not limited to the cross section arranged on both sides when the place having the maximum diameter (the place having the diameter) is vertically divided. Even if the through-hole conductor 11 is vertically divided at an arbitrary location, both the portion that becomes the first through-hole conductor 11L and the portion that becomes the second through-hole conductor 11R may be visible. Here, the distance dL in the thickness direction from the end portion 11tL of the first through-hole conductor 11L to the third conductor layer 9c is the distance in the thickness direction from the end portion 11tR of the second through-hole conductor 11R to the seventh conductor layer 9g. Shorter than dR.

Here, the distance dL in the thickness direction is a perpendicular line from the end portion 11tL of the first through-hole conductor 11L to the surface where the position of the upper surface of the third conductor layer 9c is translated in the horizontal direction, as shown in FIG. It is the length when it is lowered. As shown in FIG. 1, the distance dR in the thickness direction is when a perpendicular line is drawn from the end portion 11tR of the second through-hole conductor 11R to the surface where the position of the upper surface of the seventh conductor layer 9g is translated in the horizontal direction. Is the length of.

In the region on the left side of the printed wiring board A, the insulating layer 5b is arranged between the layers of the second conductor layer 9b and the third conductor layer 9c. In the region on the right side of the printed wiring board A, the insulating layer 5b is similarly arranged between the layers of the 7th conductor layer 9g and the 8th conductor layer 9h. In this case, the thickness t of the insulating layer 5b is the same between the region on the left side of the printed wiring board A and the region on the right side of the printed wiring board A. Here, the fact that the thickness t of the insulating layer 5b is the same means that the difference between the maximum thickness and the minimum thickness is within 10% when the thickness t of the insulating layer 5b is measured at a plurality of locations in the plane direction of the insulating layer 5b. Say if it is. In this case, the difference ΔtD between the maximum thickness and the minimum thickness is within 10%, which is expressed by the formula (tmax-tmin) / tmax = ΔtD (%) when the maximum thickness is tmax and the minimum thickness is tmin. The absolute value of the value is within 10%. The thickness t of the plurality of insulating layers 5 (here, the insulating layer 5a, the insulating layer 5b, and the insulating layer 5c) laminated to form the insulating substrate 1 may be the same, but it differs depending on the application. It may be the thickness.

The thickness of the first conductor layer 9a to the eighth conductor layer 9h may be the same, but may be different depending on the application. Here, the fact that the thickness of the conductor layer 9 is the same means that the difference ΔtM between the maximum thickness and the minimum thickness is 20% or less when the thickness of the conductor layer 9 is measured. The difference ΔtM between the maximum thickness and the minimum thickness is within 20% of the value expressed by the formula (tmax-tmin) / tmax = ΔtM (%) when the maximum thickness is tmax and the minimum thickness is tmin. The absolute value is within 20%.

In the case of the printed wiring board A, as described above, the distance dL from the end portion 11tL of the first through-hole conductor 11L to the third conductor layer 9c is from the end portion 11tR of the through-hole conductor 11R to the seventh conductor layer 9g. It is shorter than the interval dR. Due to the difference in spacing between the spacing dL and the spacing dR, the capacitance CdL generated in the insulating layer 5b located on the left side with the through hole 7 in the center and the insulating layer 5b located on the right side with the through hole 7 in the center. It is different from the capacitance CdR generated in. In this case, the third conductor layer 9c is in a state of entering the recess 7LC provided in the inner wall 7L of the through hole 7. When the third conductor layer 9c is located in the recess 7LC from the through hole 7, its capacitance goes around the recess 7LC from the end 11tL of the through hole conductor 11L to the third conductor layer 9c. Will also include the length of. Similarly, between the through-hole conductor 11R and the 7th conductor layer 9g, the length from the end 11tR of the through-hole conductor 11R to the recess 7RC and up to the 7th conductor layer 9g is included. In this way, in the printed wiring board A, when the through hole 7 is centered, the capacitance contributing to the impedance differs between the region AL on the left side and the region AR on the right side of the printed wiring board A. As a result, in the printed wiring board A, the impedance can be adjusted in each of the left region AL and the right region AR with the through hole 7 in the center.

In this case, the printed wiring board A may have a difference in inductance between the area AL and the area AR with the through hole 7 in the center. The inductance in the region AL of the printed wiring board A is such that the first conductor layer 9a, the second conductor layer 9b, and the first through-hole conductor 11L arranged so as to sandwich the first insulating layer 5a are electrically connected. Depends on length. The inductance of the printed wiring board A in the region AR is such that the fifth conductor layer 9e, the sixth conductor layer 9f, and the second through-hole conductor 11R arranged so as to sandwich the first insulating layer 5a are electrically connected. Depends on length. The printed wiring board A may have a structure having a difference between the inductance in the region AL and the inductance in the region AR.

FIG. 2 is a schematic view showing another aspect of the through-hole conductor in the printed wiring board of the embodiment. As shown in FIG. 2, the through-hole conductor 12 may have a cylindrical shape. The printed wiring board having the through-hole conductor 12 shown in FIG. 2 is hereinafter referred to as a printed wiring board B. The through-hole conductor 12 has an elliptical cut end at the end 12t. Also in the case of the through-hole conductor 12, the lengths of the opposing portions of the through-hole conductor 12 arranged in the through-hole 7 are different. The end face of the through-hole conductor 12 near the second opening 8b is inclined with respect to the central axis Z of the through-hole 7. In FIG. 2, the length LL of the left side portion of the through-hole conductor 12 is longer than the length LR of the right portion of the through-hole conductor 12. Even in such a structure, the impedance can be adjusted in the same manner as in the case of the printed wiring board A described above.

Also in this case, in the printed wiring board A described above, as shown in FIG. 1, the number of through-hole conductors 11 is the same in the left and right regions AL and AR of the through-hole 7 when the insulating substrate 1 is viewed in a vertical cross section. It is preferable that the conductor layer 9 is electrically connected to the conductor layer 9. If the through-hole conductor 11 has a structure in which the same number of conductor layers 9 are electrically connected in the left and right regions AL and AR of the through hole 7, the shape or size (length) of the through-hole conductor 11 is different. The change in the generated capacitance can be adjusted in the same insulating layer 5 (in the case of FIG. 1, the insulating layer 5c). This makes it possible to finely adjust the impedance of the printed wiring boards A and B. In the case of the through-hole conductor 12 shown in FIG. 2, when the insulating substrate 1 is viewed in a vertical cross section, it is electrically connected to the same number of conductor layers 9 in the left and right regions AL and AR of the through-hole 7. It is good to be there.

FIG. 3 is a schematic view showing another aspect of the through-hole conductor in the printed wiring board of the embodiment. In the printed wiring board C shown in FIG. 3, the shape of the through-hole conductor 11 is different from that of the printed wiring board A in FIG. The printed wiring board C of FIG. 3 is a through-hole conductor 11 and a conductor layer 9 (first conductor layer 9a, second conductor layer 9b, fifth conductor layer 9e, sixth conductor) of the printed wiring board A shown in FIG. The portion corresponding to the insulating substrate 1 existing in the layer 9f) and its surroundings is drawn.

The following description describes the through-hole conductor 11L located on the left side of the through-hole 7 of the printed wiring board C, but the through-hole conductor 11R located on the right side of the through-hole 7 also has a mirror image relationship. In this case as well, the through-hole conductor 11L is longer than the through-hole conductor 11R, as in the printed wiring board A shown in FIG. Further, in the case of the printed wiring board C shown in FIG. 3, the surface of the through-hole conductor 11L on the inner wall 7L side of the through hole 7 is the outer surface 11LA, and the surface opposite to the outer surface 11LA is the inner surface 11LB. When the outer surface 11LA is formed, the length of the insulating substrate 1 in the thickness direction is longer than that of the inner surface 111LB. Using the notation shown in FIG. 3, the length LLA of the outer surface 11LA of the through-hole conductor 11L is longer than the length LLB of the inner surface 11LB. In other words, in the through-hole conductor 11 shown in FIG. 3, the first surface (outer surface 11LA) corresponding to the inner wall 7L side of the through hole 7 is located on the opposite side of the first surface (outer surface 11LA). It is located closer to the second opening 8b than 11LB). If the length LLA of the outer surface 11LA of the through-hole conductor 11 is longer than the length LLB of the inner surface 11LB, the inductance of this portion also depends on the difference between the length LLA of the outer surface 11LA and the length LLB of the inner surface 11LB. Can be changed. In this case, as shown in FIG. 3, the end portion 11tL of the through-hole conductor 11L may be inclined so as to be gradually shortened from the outer edge end 11LAt to the inner edge end 11LBt. The end face from the outer edge end 11LAt to the inner edge end 11LBt is preferably an inclined surface. When the cross section of the end portion 11tL of the through-hole conductor 11L is inclined from the outer edge end 11LAt to the inner edge end 11LBt, the impedance varies or changes due to the inductance and capacitance generated in the direction of the length of the through-hole conductor 11L, or the change thereof. Both can be made smaller.

Further, the various printed wiring boards A and C described above have a conductor layer 9 (third conductor layer 9c, seventh conductor layer 9g) that is not electrically connected to the through-hole conductor 11 among the conductor layers 9. Had had. Hereinafter, the third conductor layer 9c and the seventh conductor layer 9g will be referred to as a non-connecting conductor layer 9c and 9g. Here, when the conductor layer 9 that is not electrically connected to the through-hole conductor 11 is used as the non-connecting conductor layer, the non-connecting conductor layers 9c and 9g are arranged so as to sandwich the through-hole 7. The length in the direction along the surface of the insulating layer 5 may be different between the two. Even in such a case, the capacitance can be changed due to the difference in the covering area with respect to the surface of the insulating layer 5 between the non-connecting conductor layer 9c and the non-connecting conductor layer 9g. This makes it possible to adjust the impedance between the regions AL and the regions AR of the printed wiring boards A and C. Needless to say, the above effect can be obtained for the printed wiring board B as well.

The following configuration will be described with reference to FIG. Further, at least one of the above-mentioned non-connecting conductors 9c and 9g may be at a position where its ends 9ct and 9gt are recessed from the

inner walls

7L and 7R of the through hole 7. When the end 9ct of the non-connecting conductor layer 9c is recessed from the inner wall 7L of the through hole 7, for example, the distance between the through-hole conductor 11L and the end 9ct of the non-connecting conductor layer 9c becomes wide. This makes it possible to further improve the insulating property between the through-hole conductor 11L and the end 9ct of the non-connecting conductor layer 9c. As a result, changes and variations in the capacitance component between the through-hole conductor 11L and the non-connecting conductor layer 9c can be made small and stable. The above effect is the same between the through-hole conductor 11R and the non-connecting conductor layer 9g.

Next, the manufacturing method of the printed wiring board A of the embodiment will be described. FIG. 4 is a cross-sectional view of a multilayer board used in the method for manufacturing the printed wiring board A of the embodiment. First, the multilayer board 20 is prepared. The multilayer board 20 has an insulating board 21 and a conductor portion 23. The multilayer board 20 has through holes 25 in the thickness direction. The insulating substrate 21 includes a plurality of insulating layers 27. The insulating substrate 21 shown in FIG. 4 is composed of a first insulating layer 27a, a second insulating layer 27b, and a third insulating layer 27c from the upper side in the thickness direction. Here, the insulating substrate 21 formed by the three-layer insulating layer 27 is used, but the number of laminated insulating layers 27 is not limited to this. As described above, the insulating substrate 27 may have a further multi-layered structure depending on the application. The conductor portion 23 includes a plurality of conductor layers 29 and a through-hole conductor bulk material 31. The conductor layer 29 includes a first conductor layer 29a, a second conductor layer 29b, a third conductor layer 29c, a fourth conductor layer 29d, a fifth conductor layer 29e, a sixth conductor layer 29f, a seventh conductor layer 29g, and an eighth conductor. It is composed of layers 29h. Each of the above-mentioned conductor layers 29 may be integrated on the same surface of each layer of the insulating layer 27.

The pair of conductor layers 29 integrated on the same surface of each layer of the insulating layer 27 is as follows. The first conductor layer 29a and the fifth conductor layer 29e are arranged on the upper surface side of the first insulating layer 27a. A second conductor layer 29b and a sixth conductor layer 29f are arranged between the first insulating layer 27a and the second insulating layer 27b. A third conductor layer 29c and a seventh conductor layer 29g are arranged between the second insulating layer 27b and the third insulating layer 27c. The fourth conductor layer 29d and the eighth conductor layer 29h are arranged on the lower surface side of the third insulating layer 27c. The through-hole conductor bulk material 31 covers the entire inner wall 25L and inner wall 25R of the through-hole 25. The through-hole conductor base 31 includes a first conductor layer 29a, a second conductor layer 29b, a third conductor layer 29c, a fourth conductor layer 29d, a fifth conductor layer 29e, a sixth conductor layer 29f, a seventh conductor layer 29g, and the like. It is in a state of being electrically connected to the eighth conductor layer 29h. In this case, as shown in FIG. 4, in the vertical cross-sectional view of the multilayer substrate 20, the through-hole conductor bulk material 31 that appears to be separated across the through-hole 25 is divided into two parts on the left and right, and is indicated by a reference numeral. The code of the through-hole conductor bulk material 31 located on the left side of the through-hole 25 is 31GL. The code of the through-hole conductor bulk material 31 located on the right side of the through-hole 25 is 31GR.

FIG. 5 is a cross-sectional view showing a printed wiring board processed body in which the protective layer 33 is formed on the multilayer substrate 20 shown in FIG. Next, in the step shown in FIG. 5, the protective layer 33 is formed on the inner surfaces 31LA and 31RA of the through-hole conductor bulk material 31 (31GL, 31GR) formed on the prepared multilayer substrate 20. Here, the multilayer board 20 on which the protective layer 33 is formed is hereinafter referred to as a printed wiring board processed body 20A. The protective layer 33 is also formed on the surfaces of the first conductor layer 29a, the fourth conductor layer 29d, the fifth conductor layer 29e, and the eighth conductor layer 29h formed on the outermost surface of the insulating substrate 21. The protective layer 33 is in contact with the through-hole conductor bulk material 31 (31GL), the first conductor layer 29a, and the fourth conductor layer 29d. The protective layer 33 is in contact with the surfaces of the through-hole conductor bulk material 31 (31GL), the first conductor layer 29a, and the fourth conductor layer 29d. The protective layer 33 is in contact with the through-hole conductor bulk material 31 (31GR), the fifth conductor layer 29e, and the eighth conductor layer 29h. The protective layer 33 is in contact with the surfaces of the through-hole conductor bulk material 31 (31GR), the fifth conductor layer 29e, and the eighth conductor layer 29h. As the material used for the protective layer 33, for example, tin or an ED film is suitable. The protective layer 33 formed of such a material is preferably formed by an electrolytic plating method for tin and an electrodeposition method for an ED film.

FIG. 6 is a cross-sectional view showing a state in which a portion of the through-hole conductor bulk material 31 provided in the printed wiring board processed body 20A shown in FIG. 5 is cut. FIG. 7 is a cross-sectional view showing a state of the printed wiring board processed body 20A after the through-hole conductor original body 31 is partially cut. In the step shown in FIG. 6, the through-hole conductor base 31 provided in the printed wiring board processed body 20A is cut to remove a part of the through-hole conductor base 31 and the protective layer 33. A part of the through-hole conductor bulk material 31 and the protective layer 33 is removed by a jig for cutting. As an example of a jig for cutting, a drilling machine can be mentioned. FIG. 6 schematically shows the tip portion of the drilling machine. The tip portion of the drill processing machine is hereinafter referred to as a drill 35. As the drill 35, a drill 35 having a tip portion 35A having a diameter (diameter or maximum diameter) larger than the inner diameter of the through-hole conductor bulk material 31 is used. The inner diameter of the through-hole conductor bulk material 31 is the portion where the double-headed arrow is designated by the symbol DT in FIG. The diameter of the tip portion 35A of the drill 35 is a portion in which a thick double-headed arrow is designated by a reference numeral DD in FIG. As the drill 35, a drill 35 having a slightly tapered tip portion 35A is used. Further, in the process of cutting with the drill 35, the axis 39 of the drill 35 is displaced from the central axis Z of the through-hole conductor original body 31.

When the tip 35A of the drill 35 has a slightly tapered shape and the axis 39 of the drill 35 is displaced from the central axis Z of the through-hole conductor original body 31, as can be seen from FIG. 6, the through after cutting is performed. Differences in length can be made on both sides of the through hole 25 of the hole conductor original body 31 sandwiched between them. The difference in length in the through-hole conductor bulk material 31 is between the through-hole conductor processed body 31GL and the through-hole conductor processed body 31GR. In FIGS. 6 and 7, the length of the through-hole conductor processed body 31GL remaining from the through-hole conductor bulk material 31 is represented by the reference numeral LTL. Further, the length of the through-hole conductor processed body 31GR remaining from the through-hole conductor bulk material 31 is represented by the reference numeral LTR. Here, the portion remaining after the cutting process is the portion of the through-hole conductor processed body 31GL from the first conductor layer 29a to the portion in contact with the tip portion 35A of the drill 35. Further, in the through-hole conductor processed body 31GR, the range is from the fifth conductor layer 29e to the portion where the tip portion 35A of the drill 35 is in contact. The length LTL of the through-hole conductor processed body 31GL, which is a portion not cut after cutting, is longer than the length LTR of the through-hole conductor processed body 31GR, which is also a portion not cut after cutting.

FIG. 8 is a cross-sectional view showing a state after etching the printed wiring board processed body 20A shown in FIG. 7. FIG. 9 is a cross-sectional view showing a state after the protective layer 33 is removed from the printed wiring board processed body 20A shown in FIG. The step of FIG. 8 is a step of etching the through-hole conductor processed body 31GL and the through-hole conductor processed body 31GR remaining after the cutting process. The etching solution used in this case dissolves the metal (copper) used in the through-hole conductor bulk material 31, but does not dissolve the protective layer 33. Examples of the etching solution include an aqueous solution of cupric chloride or an aqueous solution of ferric chloride. Such an etching process is called a half etching process. As shown in FIG. 8, when the through-hole conductor processed body 31GL and the through-hole conductor processed body 31GR are subjected to the etching process, the through-hole conductor processed body 31GL and the through-hole conductor processed body 31GR are viewed from the direction in which the drill 35 is inserted. It is further removed by a predetermined length. In this case, the length LTL of the through-hole conductor processed body 31GL after etching is shorter than the protective layer 33 in contact with the through-hole conductor processed body 31GL. The length LTR of the through-hole conductor processed body 31GR after etching is also shorter than the protective layer 33 in contact with the through-hole conductor processed body 31GR. At this time, at the same time, the third conductor layer 29c, the fourth conductor layer 29d, the seventh conductor layer 29g, and the eighth conductor layer 29h, which are not covered by the protective layer 33, are also partially removed. The third conductor layer 29c and the seventh conductor layer 29g are partially removed from the inner wall 25L and the inner wall 25R of the through hole 25 toward the back. The end portion 29ct of the third conductor layer 29c and the end portion 29gt of the seventh conductor layer 29g are recessed from the inner wall 25L and the inner wall 25R of the through hole 25. After that, as shown in FIG. 9, the protective layer 33 is removed from the printed wiring board processed body 20A. When the protective layer 33 is a tin metal film, Enstrip (manufactured by Meltex Inc.), Meckli Mover (manufactured by MEC), or the like is used to remove the metal film. In the printed wiring board processed body 20A thus obtained, as shown in FIG. 9, the length LTL of the through-hole conductor processed body 31GL is longer than the length LTR of the through-hole conductor processed body 31GR. After that, if necessary, the filler is embedded in the voids where the through-hole 25, the through-hole conductor processed body 31GL, and the through-hole conductor processed body 31GR are present. Further, if necessary, a circuit pattern is further formed on the surface of the printed wiring board processed body 20A, and then a solder resist is applied, and the surface of the exposed conductor portion 23 is selected from the group of gold, platinum, and nickel. A metal film containing at least one kind of material as a main component is formed. A plating film should be applied to the metal film. The printed wiring board A can be obtained by the above steps.

FIG. 10 shows a method of manufacturing a printed wiring board of another aspect, and shows a cross section showing a state in which a portion of the through-hole conductor original body 31 is cut with respect to the printed wiring board processed body on which the protective layer 33 is formed. It is a figure. FIG. 11 is a cross-sectional view showing a state of the printed wiring board processed body after the through-hole conductor original body 31 is partially cut. FIG. 12 is a cross-sectional view showing a state after etching the printed wiring board processed body shown in FIG. FIG. 13 is a cross-sectional view showing a state after the protective layer 33 is removed from the printed wiring board processed body shown in FIG. The printed wiring board processed body shown in FIGS. 10 to 13 is designated as a printed wiring board processed body 20B by using reference numeral B. Also in the step shown in FIG. 10, the axial center 39 of the drill 35 is shifted with respect to the central axis Z of the through hole 25. The difference between the steps shown in FIGS. 10 to 13 and the steps shown in FIGS. 6 to 12 is that the shape of the drill 35 is different. The drill 35 used here has a conical tip 35A. By using a drill 35 having a conical tip 35A, the length LTL of the through-hole conductor processed body 31GL remaining after cutting and etching is longer than the length LTR of the through-hole conductor processed body 31GR. Can be done. Further, the shapes of the through-hole conductor processed body 31GL and the end portions 31tL and 31tR of the through-hole conductor processed body 31GR can be made into the inclined shape shown in FIG.

Next, the multilayer board 20 shown in FIG. 4 was prepared, and specifically, a printed wiring board was produced by using the steps of FIGS. 5 to 9. Further, the multilayer board 20 shown in FIG. 4 was prepared, and specifically, a printed wiring board was produced by using the steps of FIGS. 10 to 13. For the multilayer substrate, FR-4 material (glass cloth base material epoxy resin) was used for the insulating layer. For the conductor layer, a copper foil or a copper foil plated with electrolytic copper was used. Here, the printed wiring board produced by using the steps of FIGS. 5 to 9 is used as sample 1. The printed wiring board produced by using the steps of FIGS. 10 to 13 is used as sample 2. FIG. 14 shows the shape of the through-hole conductor and the shapes of the first conductor layer and the fifth conductor layer formed on the surface of the produced printed wiring board when viewed in a plan view. The through-hole conductor L and the through-hole conductor R are arranged so as to be opposed to each other by providing an insulating portion on the inner wall of the through hole. The arrangement of the insulating layer and the first to eighth conductor layers is basically a four-layer structure shown in FIG. The shapes of the first to eighth conductor layers are also strip-shaped as shown in FIG. The area, length and thickness of the conductor layer formed on each insulating layer are the same. The length of the portion corresponding to the through-hole conductor L was made longer than the length of the portion corresponding to the through-hole conductor R. It was prepared so that the capacitance between the second conductor layer and the third conductor layer in Sample 1 was larger than the capacitance between the sixth conductor layer and the seventh conductor layer. The through-hole conductor of sample 2 has a cylindrical shape and an inclined end portion thereof.

The impedance of the manufactured printed wiring board was measured using an impedance analyzer. As the impedance analyzer, 4192A manufactured by Yokogawa Hewlett-Packard Co., Ltd. was used. The measurement frequency was in the range of 1 MHz to 10 MHz. For the impedance, the average value of the values obtained from the range of 1 MHz to 10 MHz was used. The measurement measured the circuits between the first conductor layer and the third conductor layer, and between the fifth conductor layer and the seventh conductor layer, respectively. The ratio of the impedance of the circuit between the 5th conductor layer and the 7th conductor layer to the average impedance of the circuit between the 1st conductor layer and the 3rd conductor layer was determined, respectively. As a comparative example, the same evaluation was performed on a sample in which the through-hole conductor was cylindrical and the difference between the length on the through-hole conductor L side and the length on the through-hole conductor R side was the same (0.01 μm or less). When the ratio of the impedance of the circuit between the 5th conductor layer and the 7th conductor layer to the average impedance of the circuit between the 1st conductor layer and the 3rd conductor layer of the sample of the comparative example is 1, the sample The impedance ratio of sample 1 tended to be larger than that of the sample of Comparative Example, and the impedance ratio of sample 2 tended to be larger than that of sample 1.

This disclosure can be used for printed wiring boards and methods for manufacturing them.

A, B, C ... Printed

wiring board

1, 21 ...

Insulation substrate

3, 23 ...

Conductor part

5, 27 ...

Insulation layer

7, 25 ... Through hole 8a ..... 1st opening 8b ........... 2nd opening 9, 29 .....

Conductor layer

11, 31 ・・・・・・・・ Through-hole conductor 20 ・・・・・・・・・ Multi-layer board 33 ・・・・・・・・ Protective layer Z ・・・・・・・・ Central axis

Claims

It has an insulating substrate and a conductor portion arranged at least inside the insulating substrate.
The insulating substrate has a plurality of laminated insulating layers and through holes penetrating from the first opening to the second opening in the thickness direction.
The conductor portion has a plurality of conductor layers and a through-hole conductor.
The plurality of conductor layers are located along the plane direction in each of the insulating layers.
The through-hole conductor has a cylindrical shape extending from the first opening toward the second opening, and is electrically connected to a part of the plurality of conductor layers at an existing position.
The plurality of conductor layers have at least one non-connecting conductor layer that is not in contact with the through-hole conductor near the second opening of the through-hole conductor.
The through-hole conductor has two ends close to the second opening in a cross-sectional view along the central axis of the through-hole, and the positions of the first end and the second end in the thickness direction are different.
Printed wiring board.
It has an insulating substrate and a conductor portion arranged at least inside the insulating substrate.
The insulating substrate has a plurality of laminated insulating layers and through holes penetrating from the first opening to the second opening in the thickness direction.
The conductor portion has a plurality of conductor layers and a through-hole conductor.
The plurality of conductor layers are located along the plane direction in each of the insulating layers.
The through-hole conductor has a cylindrical shape extending from the first opening toward the second opening, and is electrically connected to a part of the plurality of conductor layers at an existing position.
The plurality of conductor layers have at least one non-connecting conductor layer that is not in contact with the through-hole conductor near the second opening of the through-hole conductor.
The through-hole conductor is a printed wiring board in which an end surface close to the second opening is inclined with respect to the central axis of the through-hole.
The printed wiring board according to claim 1 or 2, wherein the through-hole conductor is electrically connected to the same number of conductor layers in the left and right regions of the through-hole when the insulating substrate is viewed in a vertical cross section. ..
The through-hole conductor has any one of claims 1 to 3, wherein the first surface corresponding to the inner wall side of the through hole is located closer to the second opening than the second surface located opposite to the first surface. Printed wiring board described in Crab.
The printed wiring board according to any one of claims 1 to 4, wherein the non-connecting conductor layer has portions having different lengths in the plane direction.
The printed wiring board according to claim 5, wherein the end of the non-connecting conductor layer is recessed from the inner wall of the through hole.
An insulating substrate in which a plurality of insulating layers are laminated, a conductor layer provided along the surface of the insulating layer, and a copper through-hole conductor base covering the inner wall of the through hole penetrating the insulating substrate in the thickness direction. And the process of preparing a multilayer board with
A step of forming a protective layer that is not dissolved by the copper etching solution on the entire inner wall of the through-hole conductor bulk material provided on the multilayer substrate.
Using a jig for cutting, which has a diameter larger than the inner diameter of the through-hole conductor bulk material and has a tapered tip.
The axis of the jig is arranged at a position deviated from the central axis of the through hole, and the through hole conductor original body and the protective layer are placed in the thickness direction of the multilayer substrate from one surface side of the multilayer substrate. Cut to the middle position,
A method for manufacturing a printed wiring board, which comprises a step of making the through-hole conductor bulk material electrically connected to at least two conductor layers.
The method for manufacturing a printed wiring board according to claim 7, wherein the jig is provided with a processing jig having a conical tip shape.
The method for manufacturing a printed wiring board according to claim 7 or 8, wherein a tin film is used as the protective layer.
The method for manufacturing a printed wiring board according to claim 9, wherein the through-hole conductor original body is half-etched after the tin film is peeled off.