JP7381901B2 - Manufacturing method of wiring board - Google Patents

Description

The present disclosure relates to a method for manufacturing a wiring board and a wiring board.

Printed wiring boards are widely used as supports for electronic components to obtain desired electronic circuits. A printed wiring board has an insulating substrate and a wiring pattern on the insulating substrate. This wiring pattern is generally formed by patterning a conductive film deposited on an insulating substrate by etching.

On the other hand, Patent Document 1 below discloses that after a recess is formed on the surface of a glass substrate serving as a support substrate by irradiation with an ultraviolet laser, conductive ink is applied to the recess and hardened, thereby forming wiring inside the recess. Discloses technology to do so. Patent Document 2 below discloses a technique for obtaining a wiring board having vias penetrating a supporting substrate by forming grooves and through holes in an insulating sheet using a laser and placing a conductive paste inside these structures. is disclosed.

JP2015-029031A Japanese Patent Application Publication No. 2006-060150

To provide a wiring board that can be manufactured through a simple process and has improved reliability.

A method for manufacturing a wiring board according to the present disclosure includes a first groove structure forming step of forming a first groove structure having a first width on the first main surface of a base having a first main surface by scanning with a laser beam. a first irradiation step of further irradiating the inside of the first groove structure with a laser beam in an irradiation pattern different from the irradiation pattern in the first groove structure forming step; and filling the first groove structure with a first conductive material. and forming a first wiring pattern from the first conductive material that matches the planar shape of the first groove structure.

For example, the reliability of the wiring board is improved by suppressing peeling of the wiring pattern from the support.

1 is a flowchart illustrating an exemplary method of manufacturing a wiring board, according to an embodiment of the present disclosure. FIG. 1 is a perspective view for explaining a method for manufacturing a wiring board according to an embodiment of the present disclosure. FIG. 3 is a schematic plan view showing an example of the base 100S after the first groove structure 110 is formed. 4 is a schematic plan view showing a state after the inside of the first groove structure 110 is further irradiated with laser light from the state shown in FIG. 3. FIG. 5 is a schematic cross-sectional view showing an enlarged cross-section of a part of the base 100S shown in FIG. 4. FIG. FIG. 1 is a schematic cross-sectional view for explaining a method of manufacturing a wiring board according to an embodiment of the present disclosure. FIG. 2 is a schematic plan view for explaining a method for manufacturing a wiring board according to an embodiment of the present disclosure. FIG. 3 is a schematic diagram for explaining an additional polishing step in a method for manufacturing a wiring board according to an embodiment of the present disclosure. FIG. 6 is a diagram for explaining a modification of the method for manufacturing a wiring board according to an embodiment of the present disclosure, in which the inside of the first groove structure 110 is irradiated with a laser beam using a different irradiation pattern than when the first groove structure 110 is formed; FIG. 3 is a schematic plan view showing the state after irradiation with LB. 10 is a schematic sectional view showing an enlarged cross section of a part of the base 100S shown in FIG. 9. FIG. FIG. 7 is a schematic cross-sectional view for explaining a modification of the method for manufacturing a wiring board according to an embodiment of the present disclosure. FIG. 7 is a schematic plan view for explaining a modification of the method for manufacturing a wiring board according to an embodiment of the present disclosure. FIG. 7 is a schematic plan view for explaining a further modification of the method for manufacturing a wiring board according to an embodiment of the present disclosure. 5 is a flowchart illustrating a portion of an exemplary method for manufacturing a wiring board, according to another embodiment of the present disclosure. FIG. 7 is a perspective view for explaining a method of manufacturing a wiring board according to another embodiment of the present disclosure. 7 is a schematic plan view showing an example of the base 100S after the formation of the second groove structure 120. FIG. 17 is a schematic plan view showing a state after the inside of the second groove structure 120 is further irradiated with laser light from the state shown in FIG. 16. FIG. FIG. 7 is a schematic cross-sectional view for explaining a modification of the method for manufacturing a wiring board according to another embodiment of the present disclosure. FIG. 7 is a schematic plan view for explaining a method for manufacturing a wiring board according to another embodiment of the present disclosure. 20 is a schematic cross-sectional view corresponding to the plan view shown in FIG. 19. FIG. FIG. 7 is a diagram for explaining a modification of the method for manufacturing a wiring board according to another embodiment of the present disclosure, in which after forming the second groove structure 120, an irradiation pattern different from that at the time of forming the second groove structure 120 is used. 7 is a schematic plan view showing a state after the inside of the second groove structure 120 is irradiated with a laser beam LB. FIG. 22 is a schematic cross-sectional view showing an enlarged cross-section of a part of the base 100S shown in FIG. 21. FIG. 23 is a schematic cross-sectional view showing a state in which a second wiring pattern is formed from the state shown in FIG. 22. FIG. FIG. 7 is a schematic cross-sectional view showing a further modified example of the wiring board according to Embodiment 2 of the present disclosure. 25 is a schematic cross-sectional view for explaining an exemplary manufacturing method of wiring board 100E shown in FIG. 24. FIG. 25 is a schematic cross-sectional view for explaining an exemplary manufacturing method of wiring board 100E shown in FIG. 24. FIG. 25 is a schematic cross-sectional view for explaining an exemplary manufacturing method of wiring board 100E shown in FIG. 24. FIG. 25 is a schematic cross-sectional view for explaining an exemplary manufacturing method of wiring board 100E shown in FIG. 24. FIG. It is a typical sectional view showing a modification in which conductive paste 130r is selectively applied to the inner surface of through hole 150p. 7 is a schematic cross-sectional view showing a modification in which a through hole 150q is formed in the base 100S before forming the second groove structure 120. FIG. FIG. 7 is a diagram showing a microscope image of the first bottom surface of the sample of Example 1-1. FIG. 3 is a diagram showing a cross-sectional profile of the sample of Example 1-1. FIG. 7 is a diagram showing a microscope image of the first bottom surface of the sample of Example 1-2. FIG. 3 is a diagram showing a cross-sectional profile of a sample of Example 1-2. FIG. 7 is a diagram showing a microscope image of the first bottom surface of the sample of Example 1-3. FIG. 3 is a diagram showing a cross-sectional profile of a sample of Example 1-3. FIG. 7 is a diagram showing a microscope image of the first bottom surface of the sample of Example 1-4. FIG. 4 is a diagram showing a cross-sectional profile of a sample of Example 1-4. 3 shows a microscope image of the first bottom surface of the sample of Reference Example 1-1. FIG. 3 is a diagram showing a cross-sectional profile of a sample of Reference Example 1-1. It is a figure which shows the microscopic image of the 2nd part before filling with a conductive paste. It is a figure which shows the microscopic image regarding the cross section after filling a 2nd part with electrically conductive paste and hardening electrically conductive paste. It is a figure which shows the microscopic image of the 3rd part before filling with a conductive paste. It is a figure which shows the microscopic image regarding the cross section after filling a 3rd part with a conductive paste and hardening a conductive paste. It is a figure which shows the microscopic image of the 4th part before filling with a conductive paste. It is a figure which shows the microscopic image regarding the cross section after filling a 4th part with electrically conductive paste and hardening electrically conductive paste. FIG. 7 is a diagram showing a microscope image of the first bottom surface of the sample of Example 2-1. FIG. 7 is a diagram showing a cross-sectional profile of the sample of Example 2-1. FIG. 7 is a diagram showing a microscope image of the first bottom surface of the sample of Example 2-2. FIG. 7 is a diagram showing a cross-sectional profile of a sample of Example 2-2. FIG. 7 is a diagram showing a microscope image of the first bottom surface of the sample of Example 2-3. FIG. 7 is a diagram showing a cross-sectional profile of a sample of Example 2-3. FIG. 7 is a diagram showing a microscope image of the first bottom surface of the sample of Example 2-4. FIG. 7 is a diagram showing a cross-sectional profile of a sample of Example 2-4. FIG. 7 is a diagram showing a cross-sectional profile of a sample of Reference Example 2-1. It is a figure which shows the microscopic image of the 6th part before filling with a conductive paste. It is a figure which shows the microscopic image regarding the cross section after filling a 6th part with a conductive paste and hardening a conductive paste. It is a figure which shows the microscopic image of the 8th part before filling with a conductive paste. It is a figure which shows the microscopic image regarding the cross section after filling an 8th part with the electrically conductive paste and hardening the electrically conductive paste. It is a figure which shows the microscopic image of the 9th part before filling with a conductive paste. It is a figure which shows the microscope image regarding the cross section after filling a 9th part with electrically conductive paste and hardening electrically conductive paste. FIG. 7 is a diagram showing a microscope image of the first bottom surface of the sample of Example 3-3 before being filled with conductive paste. FIG. 7 is a plan view showing the appearance of the first wiring pattern after the tape is peeled off regarding the sample of Example 3-3. FIG. 7 is a diagram showing a microscope image of the first bottom surface of the sample of Comparative Example 3-1 before being filled with conductive paste. FIG. 7 is a plan view showing the appearance of the first wiring pattern after tape peeling regarding the sample of Comparative Example 3-2.

Embodiments of the present disclosure will be described in detail below with reference to the drawings. The following embodiments are
The wiring board and the manufacturing method thereof according to the present disclosure are not limited to the following embodiments, which are merely examples. For example, the numerical values, shapes, materials, steps, order of steps, etc. shown in the following embodiments are merely examples, and various modifications can be made as long as there is no technical contradiction.

The dimensions, shapes, etc. of the components shown in the drawings may be exaggerated for the sake of clarity, and the dimensions, shapes, and sizes of the components in the actual translucent member, light emitting device, and manufacturing equipment may differ. It may not reflect the relationship. In addition, some elements may be omitted to avoid overly complicating the drawings.

In the following description, components having substantially the same functions are indicated by common reference numerals, and the description thereof may be omitted. In the following description, terms may be used to indicate particular directions or positions (eg, "top," "bottom," "right," "left," and other terms including those terms). However, these terms are used only for clarity of relative orientation or position in the referenced drawings. If the relative directions or positional relationships using terms such as "upper" and "lower" in the referenced drawings are the same, the drawings other than this disclosure, actual products, manufacturing equipment, etc., are the same as the referenced drawings. It doesn't have to be the placement. In the present disclosure, "parallel" includes cases where two straight lines, sides, planes, etc. are within a range of about 0° to ±5°, unless otherwise specified. Furthermore, in the present disclosure, "perpendicular" or "orthogonal" includes cases where two straight lines, sides, planes, etc. are within a range of approximately ±5° from 90°, unless otherwise specified.

(Embodiment 1 of wiring board manufacturing method)
FIG. 1 illustrates an exemplary method of manufacturing a wiring board, according to an embodiment of the present disclosure. In the method for manufacturing the wiring board shown in FIG. 1, the step of forming a groove structure on the main surface of the base by laser beam scanning (step S1) is different from the irradiation pattern in the step of forming the groove structure. A step of further irradiating the inside of the groove structure with a laser beam using an irradiation pattern (step S2), and a step of filling the groove structure with a first conductive material to form a first wiring pattern from the first conductive material (step S3). including. The details of each step will be explained below.

(First groove structure forming step (A))
First, a base having a main surface is prepared. Here, a base 100S having a top surface 100a as a first main surface as shown in FIG. 2 is illustrated. Note that FIG. 2 also shows arrows indicating the X direction, Y direction, and Z direction that are orthogonal to each other. Arrows indicating these directions may also be illustrated in other figures of this disclosure.

In this example, the outer shape of the base 100S when viewed perpendicularly to the top surface 100a is rectangular, and the sides of the rectangle coincide with the X and Y directions shown in the figure. However, it is not essential that the outer shape of the base 100S is rectangular, and the base 100S may have any shape. In the following, an example will be described in which a plate-shaped member having a lower surface 100b as a second main surface located on the opposite side of the upper surface 100a is used as the base 100S. The upper surface 100a and lower surface 100b of the base 100S are typically flat surfaces. However, the upper surface 100a and the lower surface 100b of the base 100S are not limited to flat surfaces, and one or both of the upper surface 100a and the lower surface 100b may include at least a portion of a curved surface or have a step. I don't mind.

As the base 100S, for example, various substrates defined in the ANSI/NEMA standards can be applied. In particular, resin substrates such as glass fiber reinforced resin substrates (glass epoxy substrates), flexible substrates made of resin films such as polyimide, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and silicone, and aluminum nitride. , aluminum oxide, zirconium oxide, or the like can be suitably used as the base 100S, but the base 100S is not limited to these examples. The base 100S may be prepared by purchase, or may be prepared by firing a green sheet or the like.

Next, the main surface of the base is irradiated with laser light, and a groove structure is formed on the main surface of the base by scanning the laser light (step S1 in FIG. 1). A known laser ablation device can be applied to the laser beam irradiation. FIG. 2 schematically shows an example in which a laser ablation apparatus 300 including a laser light source 310 and a galvanometer mirror 320 is applied. The number of galvano mirrors in laser ablation device 300 may be two or more. Examples of the laser light source 310 are a _CO2 laser, a Nd:YAG laser, a Nd: _YVO4 laser, and the like. Alternatively, it is also possible to use a laser light source called a green laser that outputs a laser having a wavelength of 532 nm as the laser light source 310.

In this step, the upper surface 100a of the base 100S is scanned with the laser beam LB. By scanning the laser beam LB, a part of the upper surface 100a side of the base 100S is removed, and as schematically shown in FIG. 2, a first groove structure 110 having a first width W1 is formed on the upper surface 100a. be done. At this time, if a material that absorbs the laser beam is dispersed in the base 100S, the laser beam can be efficiently absorbed into the base 100S, and a portion of the surface of the base 100S can be efficiently removed. Therefore, it is beneficial. A typical example of a material that absorbs laser light is a colorant. For example, when a UV laser whose center wavelength is in the ultraviolet region is used as the laser light source 310, a filler such as titanium dioxide, carbon, barium sulfate, or zinc oxide may be dispersed in the base 100S as a material that absorbs laser light. . When a green laser is used as the laser light source 310, carbon, nickel oxide, iron (III) oxide, etc. can be used as a filler, and when an IR laser whose center wavelength is in the infrared region is used, carbon, Calcium sulfate, magnesium silicate, aluminum oxide, tungsten composite oxide, etc. can be used as fillers.

Here, by scanning the beam LB in a certain direction (first direction), a plurality of first grooves 111 each extending along the first direction are formed on the upper surface 100a side of the base 100S, thereby forming A first groove structure 110 is formed. Note that FIG. 2 schematically shows a state in the middle of forming the first groove structure 110. For scanning the beam LB, a galvanometer mirror may be used as in the example in FIG. 2, or a base 100S may be placed on a stage made of quartz glass, etc., and the laser beam may be scanned while the stage is moved within the XY plane. irradiation may be performed. In the example shown in FIG. 2, the first direction is different from both the X direction and the Y direction in the figure. However, the scanning direction of the beam LB is arbitrary, and the first direction may coincide with the X direction or the Y direction.

By forming the plurality of first grooves 111 at an appropriate pitch, as schematically shown in FIG. A single groove structure 110 can be formed. In the example shown in FIG. 2, the first groove structure 110 includes a portion that extends in a direction different from the first direction and has a first width W1. Here, the first width W1 is a length measured in a direction perpendicular to the direction in which the focused portion of the first groove structure 110 extends. As understood from the above principle of formation of the first groove structure 110, the first width W1 is larger than the second width, which is the width of each of the plurality of first grooves 111.

FIG. 3 shows an example of the base 100S after the first groove structure 110 is formed. In the example shown in FIG. 3, the first groove structure 110 is formed on the upper surface 100a of the base 100S to include a first portion 110A having three branches and a Y-shaped second portion 110B. There is. The shape of the first groove structure 110 when viewed from the normal direction of the upper surface 100a of the base 100S is arbitrary. The first groove structure 110 may include a branch, a bend, etc., for example, like the first portion 110A shown in FIG. It's okay to stay. As in the example shown in FIG. 3, when the first groove structure 110 includes a plurality of parts, the shape and arrangement of each part and the number of the plurality of parts are also arbitrary. The shape of the first groove structure 110 illustrated in FIG. 3 is merely an example for explanation, and it goes without saying that the shape of the first groove structure 110 is not limited to the illustrated shape.

As described above, each of the plurality of first grooves 111 forming the bottom of the first groove structure 110 extends along the first direction. In FIG. 3, this first direction is indicated by a double-headed arrow d1. Each of the first grooves 111 is typically formed by irradiating pulses of laser light along the first direction so that laser spots partially overlap. Therefore, the direction in which the first groove structure 110 extends is not restricted by the first direction, that is, the direction in which the first groove 111 extends. Note that the direction of movement of the laser spot between two adjacent first grooves 111 when forming these grooves may be common or may be antiparallel (that is, reciprocating movement).

(First irradiation step (B))
Next, the inside of the first groove structure is further irradiated with laser light using an irradiation pattern different from the irradiation pattern in the step of forming the first groove structure (step S2 in FIG. 1). For example, a plurality of recesses are formed at the bottom of the first groove structure 110 by irradiating the bottom of the first groove structure 110 with a laser beam LB in pulses.

FIG. 4 schematically shows a state after the inside of the first groove structure 110 is further irradiated with laser light from the state shown in FIG. In this example, a plurality of dot-shaped recesses are formed at the bottom of the first groove structure 110 by irradiating the bottom of the first groove structure 110 with laser light. Hereinafter, these plurality of recesses will be referred to as "first recesses 111d."

In this way, by irradiating the laser beam LB in pulses overlapping the set of the plurality of first grooves 111 constituting the bottom of the first groove structure 110, for example, a plurality of first grooves 111 are formed inside the first groove structure 110. A recessed portion 111d can be formed. As schematically shown in FIG. 4, the first recess 111d may have a diameter larger than the width (second width) of each first groove 111. Note that in FIG. 4, the first recess 111d is exaggerated and drawn for convenience of explanation. In subsequent figures, the first recessed portion 111d and the like may be illustrated in an exaggerated manner.

Here, the plurality of first recesses 111d are arranged in a triangular lattice shape. Of course, the arrangement of the plurality of first recesses 111d is arbitrary. Typically, the first recesses 111d are formed at the bottom of the first groove structure 110 to have a uniform density. The plurality of first grooves 111 described above may have a pitch in a range of, for example, 10% or more and 100% or less with respect to the center-to-center distance between the two first recesses 111d.

The irradiation pattern in the process of further irradiating the bottom of the first groove structure 110 with laser light is different from the irradiation pattern used when forming the first groove structure 110. For example, by intermittently irradiating the bottom of the first groove structure 110 with a laser beam along a second direction (indicated by a double-headed arrow d2 in FIG. 4) that intersects the first direction, A plurality of aligned first recesses 111d can be formed at the bottom of the first groove structure 110. By repeating this scanning, a plurality of first recesses 111d can be formed in the bottom of the first groove structure 110, for example, in a triangular lattice shape. For example, a direction perpendicular to the first direction can be selected as the second direction. However, it is not essential that the second direction is perpendicular to the first direction.

Note that the scanning direction of the laser beam in this step is not limited to a direction different from the above-mentioned first direction. That is, the scanning direction of the laser beam in forming the plurality of first recesses 111d may coincide with the first direction. In this specification, "the irradiation patterns are different" is not limited to an operation in which the locus of movement of the laser spot is different, and is not limited to an operation in which the locus of movement of the laser spot is different; It is broadly interpreted to include operations in which the laser spot's movement locus (or the laser head's relative movement locus with respect to the stage) is the same, but the laser output, pulse interval, etc. are different from each other.

FIG. 5 schematically shows an enlarged cross section of a part of the base 100S shown in FIG. 4. As shown in FIG. The cross section shown in FIG. 4 corresponds to a cross section when the base 100S is cut along a plane perpendicular to the first direction in which the plurality of first grooves 111 extend. As schematically shown in FIG. 5, the first groove structure 110 includes a first bottom surface 110b formed by a set of a plurality of first grooves 111. Each of the plurality of first grooves 111 has a second width W2. Here, the second width W2 is smaller than the first width W1 of the first groove structure 110.

The position of the first bottom surface 110b of the first groove structure 110 generally corresponds to the position of the plurality of tops formed between two mutually adjacent first grooves 111. The distance from the first bottom surface 110b of the first groove structure 110 to the upper surface 100a of the base 110S, in other words, the depth Dp1 of the first groove structure 110 may be in a range of, for example, about 5 μm or more and 50 μm or less.

For example, by irradiating one or more first grooves 111 with laser light, a part of the first bottom surface 110b can be further removed, and a plurality of first recesses 111d can be formed as deeper parts in the first bottom surface 110b. . Note that the laser output in the process of forming the plurality of first recesses 111d may be the same as the laser output in the process of forming the first groove structure 110, or may be higher.

The plurality of first recesses 111d may include recesses with different depths. For example, by alternately forming two-dimensional dot-shaped recesses with different depths, a stronger anchoring effect can be exerted on the conductive material described below.

(First wiring pattern forming step (C))
Next, the first groove structure is filled with a first conductive material to form a first wiring pattern from the first conductive material (step S3 in FIG. 1). Here, as schematically shown in FIG. 6, the first groove structure 110 is filled with a conductive paste 130r as a first conductive material. FIG. 6 shows an example in which the conductive paste 130r is placed inside the first groove structure 110 by printing using a squeegee 190. As the conductive paste 130r, a material in which particles of Au, Ag, Cu, etc. are dispersed in a base material such as epoxy resin can be used. For example, a known Au paste, Ag paste, or Cu paste may be used as the conductive paste 130r. The conductive paste 130r may contain a solvent. Instead of the conductive paste 130r, for example, an alloy material containing copper powder in Sn--Bi solder may be used as the first conductive material.

First, a conductive paste 130r is applied inside the first groove structure 110 or on the upper surface 100a of the base 110S, and the squeegee 190 is moved on the upper surface 100a as shown by the thick arrow MV in FIG. At this time, a portion of the conductive paste 130r enters the inside of the first groove 111 and the inside of the first recess 111d. That is, the inside of the first groove 111 and the inside of the first recess 111d are filled with the conductive paste 130r.

By moving the squeegee 190, a portion of the conductive paste 130r applied on the base 100S that is higher than the upper surface 100a of the base 100S is removed. By removing unnecessary portions of the conductive paste 130r, the surface 130ra of the conductive paste 130r can be approximately aligned with the upper surface 100a of the base 100S.

The method of applying the conductive paste 130r to the base 100S is not limited to the method using a squeegee. The conductive paste 130r can be applied using various methods such as spin coating, dip coating, screen printing, offset printing, flexographic printing, gravure printing, microcontact, inkjet, nozzle printing, and aerosol jet. Printing methods can be applied. Of course, the conductive paste 130r may be applied to the base 100S by a method other than the printing method.

Thereafter, the conductive paste 130r placed inside the first groove structure 110 is cured by heating or light irradiation. By curing the conductive paste 130r, as schematically shown in FIG. 7, the first wiring pattern 131 has a shape that matches the shape of the first groove structure 110 when viewed from the normal direction of the upper surface 100a of the base 100S. can be formed from conductive paste 130r. Through the above steps, a wiring board 100A having the first wiring pattern 131 on the upper surface 100a side is obtained.

If the surface of the conductive paste 130r is raised from the upper surface 100a of the base 100S after the conductive paste 130r is cured, an additional polishing step may be performed as necessary after the conductive paste 130r is cured. Good too. In the example shown in FIG. 8, the surface of the hardened conductive paste 130r and the upper surface 100a of the base 100S are polished using a grinding wheel 200 attached to a grinder device or the like. By polishing, the upper surface 131a of the first wiring pattern 131, which is the polished surface, can be aligned with the upper surface 100a of the base 100S. Further, the residue of the conductive paste 130r attached to the upper surface 100a of the base 100S can be removed. If necessary, a copper plating layer or a nickel-gold plating layer may be formed on the hardened conductive paste 130r.

According to this embodiment, a wiring board on which a wiring pattern having an arbitrary shape is formed can be obtained through a relatively simple process. As is clear from the above, the shape of the first wiring pattern 131 is determined by the shape of the first groove structure 110. Since the first groove structure 110 is formed by laser beam irradiation, a high degree of freedom can be obtained regarding the shape of the first wiring pattern 131. Since it is possible to form a relatively deep first groove structure of approximately 5 μm or more and 50 μm or less, it is easier to control the thickness of the wiring pattern compared to patterning that involves etching, especially for wiring with a high aspect ratio. can be formed. Increasing the aspect ratio is advantageous in reducing wiring resistance. According to the method of this embodiment, it is also relatively easy to form wiring in the form of highly accurate thin lines. Further, since the first wiring pattern 131 can be formed by curing the conductive paste as the first conductive material, an etching process can be omitted. Therefore, there are no costs related to waste liquid treatment.

Furthermore, in the above example, the inside of the first groove structure 110 is further irradiated with laser light using an irradiation pattern different from the irradiation pattern in the step of forming the first groove structure 110. By the second laser beam irradiation, it is possible to further form irregularities such as a plurality of first recesses 111d on the first bottom surface 110b including the plurality of first grooves 111. As described above, since the first conductive material is typically arranged inside the plurality of first recesses 111d, a portion of the first wiring pattern 131 is also generally arranged inside the plurality of first recesses 111d. It has a cross-sectional shape that is located at . By locating a portion of the first wiring pattern 131 inside the plurality of first recesses 111d that are deeper than the first bottom surface 110b, the area of the interface between the first wiring pattern 131 and the base 100S increases. By increasing the interface area between the first wiring pattern 131 and the base 100S, a stronger anchor effect can be obtained. Thereby, peeling of the first wiring pattern 131 from the base 100S can be suppressed. That is, it becomes possible to provide a wiring board with improved reliability. Note that by applying a silane coupling agent inside the first groove structure 110 before placing the first conductive material, the effect of suppressing peeling of the first wiring pattern 131 can be further improved.

As described with reference to FIG. 8, by additionally performing a polishing process after the conductive paste is hardened, the upper surface 131a of the first wiring pattern 131 can be aligned with the upper surface 100a of the base 100S. Therefore, it is possible to provide a thinner wiring board in which the wiring does not protrude from the upper surface 100a of the base 100S. While the wiring of a conventional printed wiring board formed by etching a conductor film protrudes from the surface of the substrate that supports the wiring, in the exemplary embodiment of the present disclosure, the surface of the wiring pattern is at the same level or even lower than the surface. That is, a thin wiring board having a high aspect ratio and fine wiring can be advantageously provided. It is also easy to make the upper surface 131a of the first wiring pattern 131 and the upper surface 100a of the base 100S substantially in the same plane, and it is possible to provide a wiring board with excellent mounting performance.

(Modified example)
In the above-described example described with reference to FIG. 4 and the like, a plurality of dot-shaped first recesses 111d are formed on the first bottom surface 110b by further irradiating the first bottom surface 110b of the first groove structure 110 with laser light. ing. However, the irradiation pattern in the process of further irradiating the first bottom surface 110b with laser light is not limited to the above-mentioned example. For example, a plurality of second grooves are formed on the first bottom surface 110b by scanning along the second direction. may be formed.

FIG. 9 is a diagram showing a modification of the first embodiment described above, in which after forming the first groove structure 110, the inside of the first groove structure 110 is exposed using an irradiation pattern different from that used when forming the first groove structure 110. The state after irradiation with the laser beam LB is schematically shown. In the example shown in FIG. 9, by scanning the laser beam LB in the second direction on the first bottom surface 110b, a plurality of second grooves similar to the first grooves 111 described above, each extending in the second direction, are formed. 112 is further formed inside the first groove structure 110.

Here, the second direction is a direction different from the first direction, and typically is a direction orthogonal to the first direction. However, the second direction is not limited to a direction orthogonal to the first direction, and any direction other than the first direction may be selected as the second direction. By forming the plurality of second grooves 112 overlapping the plurality of first grooves 111, a deeper portion can be formed at the position where the first grooves 111 and the second grooves 112 intersect. These relatively deep portions may be dot-shaped recesses similar to the plurality of first recesses 111d.

FIG. 10 is an enlarged view showing a cross section of a part of the base 100S shown in FIG. is schematically shown. The first groove structure 110 includes a first bottom surface 110b formed by a set of a plurality of first grooves 111, which is similar to the above example, but here, the base 100S using laser beam scanning is By partially removing the grooves, a plurality of second grooves 112 are further formed in the first bottom surface 110b. In this example, by forming a plurality of second grooves 112 overlapping a plurality of first grooves 111, a deeper portion is formed at a position where the first grooves 111 and second grooves 112 intersect. Hereinafter, these deeper portions may be referred to as "first recessed portions 112d" for convenience.

Each of the plurality of second grooves 112 has a third width W3. The third width W3 is smaller than the first width W1 of the first groove structure 110. Setting values such as laser output and pulse intervals in the step of forming the plurality of second grooves 112 may be the same as or different from the setting values in the step of forming the plurality of first grooves 111. The arrangement pitch of the second grooves 112 may also be the same as or different from the arrangement pitch of the first grooves 111.

Instead of forming the plurality of first recesses 111d by irradiating the laser beam LB at intervals along the second direction, as in this example, by further irradiating the laser beam, the plurality of first recesses 111d are formed. A plurality of second grooves 112 may be formed extending in a direction different from the direction in which one groove 111 extends (ie, the first direction). According to this embodiment, an arbitrary pattern can be relatively easily formed at the bottom of the first groove structure 110 by irradiating laser light with different irradiation patterns. As in this example, a plurality of second grooves 112 each having a width smaller than the first width W1 are formed on the first bottom surface 110b to obtain a first groove structure 110 having grid-like irregularities on the bottom. This can be expected to improve the anchoring effect. That is, peeling of the first wiring pattern 131 from the base 100S can be suppressed, and reliability of the wiring board can be improved.

In particular, as shown in FIG. 10, by forming a plurality of second grooves 112 on the first bottom surface 110b that overlap and cross the plurality of first grooves 111, the first grooves 111 and the second grooves 112 are A first recess 112d deeper than these grooves can be formed at the intersection. By forming the first recesses 112d in this manner, the anchor effect can be further improved as in the case where a plurality of dot-shaped first recesses 111d are formed. Also in this example, by applying a silane coupling agent inside the first groove structure 110 before placing the first conductive material, the effect of suppressing peeling of the first wiring pattern 131 can be improved. I can do it.

The steps after forming the plurality of second grooves 112 may be similar to the previous example described with reference to FIGS. 6 and 7. That is, after forming the plurality of second grooves 112, as schematically shown in FIG. 11, the inside of the first groove structure 110 is filled with a first conductive material, for example, a conductive paste 130r. At this time, the inside of the first recess 112d is filled with the conductive paste 130r.

After applying the conductive paste 130r to the base 100S, by curing the conductive paste 130r, a wiring board 100B including a first wiring pattern 131 having a shape matching the first groove structure 110 is formed, as in the example of FIG. can be obtained (see FIG. 12). In the wiring board 100B, the first bottom surface 110b of the first groove structure 110 includes, in addition to the plurality of first grooves 111, a plurality of second grooves 112 each extending in a direction different from the direction in which the plurality of first grooves 111 extend. including. Similar to the example described with reference to FIG. 8, the surface of the hardened conductive paste 130r and the upper surface 100a of the base 100S may be polished, if necessary.

Note that in each of the above examples, the plurality of first grooves 111 are formed by scanning the laser beam along the first direction. However, the locus of movement of the laser spot in forming the first groove structure 110 is not limited to repeated linear movement along a single direction. For example, as schematically shown in FIG. 13 by a broken circle and a solid arrow, the surface of the base 100S is partially removed by scanning the laser beam so that the laser spot moves in a zigzag manner, A first groove structure 110 may be formed. Further, the first groove 111 is not limited to the shape of a plurality of linear grooves parallel to each other, but may have a groove shape such as a concentric circle shape, a concentric polygonal shape, a spiral shape, etc. in plan view.

(Embodiment 2 of wiring board manufacturing method)
After forming the first wiring pattern 131 on the upper surface 100a side of the base 100S, a further wiring pattern may be formed on the lower surface 100b side of the base 100S by the same method as described above. For example, a double-sided board can be obtained by further forming a wiring pattern on the lower surface 100b side of the base 100S.

FIG. 14 illustrates a portion of an exemplary method for manufacturing a wiring board according to another embodiment of the present disclosure. The method for manufacturing a wiring board illustrated in FIG. 14 includes a step of forming a second groove structure on the other main surface of the base by scanning with a laser beam (step S4), and an irradiation pattern in the step of forming the second groove structure. The step includes further irradiating the inside of the second groove structure with a laser beam using a different irradiation pattern (step S5), and filling the second groove structure with a second conductive material to form a second wiring pattern from the second conductive material. step (step S6). The details of each step will be explained below.

(Second groove structure formation step (D))
Each step shown in FIG. 14 can be executed after steps S1 to S3 described with reference to FIG. 1 are executed. For example, a wiring board 100A manufactured according to the above-described procedure is prepared. A wiring board 100B shown in FIG. 12 may be used instead of the wiring board 100A.

Next, in the same manner as the example described with reference to FIG. 2, the lower surface 100b (second major surface), which is the other major surface of the base 100S, is irradiated with a laser beam, and the lower surface 100b is scanned by the laser beam. A second groove structure is formed (step S4 in FIG. 14). For example, similarly to the example described with reference to FIG. 2, the laser ablation device 300 is used to scan the lower surface 100b of the base 100S with the laser beam LB. By scanning the laser beam LB, a part of the lower surface 100b side of the base 100S is removed, and as schematically shown in FIG. 15, a second groove structure 120 having a fourth width W4 is formed on the lower surface 100b. be done. Here, the fourth width W4 regarding the second groove structure 120 means the length measured in the direction perpendicular to the direction in which the focused portion of the second groove structure 120 extends.

By scanning the beam LB in a certain direction, for example, the third direction, on the lower surface 100b of the base 100S, as schematically shown in FIG. 15, a plurality of third grooves 123 each extending along the third direction are formed. can be formed on the lower surface 100b side of the base 100S. FIG. 15 schematically shows a state in the middle of the formation of the second groove structure 120. The third direction, which is the scanning direction of the beam LB in the step of forming the plurality of third grooves 123, may be parallel to the above-mentioned first direction or second direction, or may be a direction different from either of these. It's okay.

Here, similarly to the formation of the first groove structure 110 on the upper surface 100a side of the base 100S, a plurality of third grooves 123 are formed by scanning the laser beam LB. By forming a plurality of third grooves 123 each extending along the third direction at an appropriate pitch, it is possible to form a second groove structure 120 having a bottom defined by a set of the plurality of third grooves 123. can.

In the example shown in FIG. 15, the second groove structure 120 includes a portion that extends in a direction different from the third direction and has a fourth width W4. As can be easily understood from the principle of formation of the second groove structure 120, if each third groove 123 has a fifth width W5 (see FIG. 18 described later), the fifth width W5 is It is smaller than the fourth width W4 of the second groove structure 120.

FIG. 16 shows an example of the base 100S after the second groove structure 120 is formed. In FIG. 16, the third direction in which the plurality of third grooves 123 extend is schematically indicated by a double-headed arrow d3. In the configuration illustrated in FIG. 16, the second groove structure 120 has a generally linear shape extending in a direction different from the third direction described above. As schematically shown in FIG. 16, in this example, a part of the second groove structure 120 on the lower surface 100b side of the base 100S overlaps with the first groove structure 110 located on the upper surface 100a side of the base 100S. There is. Of course, the shape of the second groove structure 120 in plan view is arbitrary like the first groove structure 110 described above. When the second groove structure 120 includes a plurality of parts, the shape and arrangement of each part and the number of the plurality of parts are also arbitrary.

In this embodiment, since the second groove structure 120 is formed by forming the plurality of third grooves 123 using laser light, a high degree of freedom can be obtained regarding the shape of the second groove structure 120. The laser light irradiation conditions in the step of forming the second groove structure 120 may be the same as or different from the laser light irradiation conditions in the step of forming the first groove structure 110.

(Second irradiation step (E))
Next, the inside of the second groove structure is further irradiated with a laser beam using an irradiation pattern different from the irradiation pattern in the step of forming the second groove structure (step S5 in FIG. 14). For example, by irradiating the bottom of the second groove structure 120 with a laser beam LB in pulses, the second groove structure 120 is A plurality of recesses can be formed in the bottom of the recess.

FIG. 17 schematically shows a state after the inside of the second groove structure 120 is further irradiated with laser light from the state shown in FIG. 16. In this example, a plurality of dot-shaped second recesses 123d are formed at the bottom of the second groove structure 120 by irradiating the bottom of the second groove structure 120 with laser light. As schematically shown in FIG. 17, the diameter of the second recess 123d is typically larger than the width (fifth width) of each third groove 123.

The irradiation pattern in the step of further irradiating the bottom of the second groove structure 120 with laser light is different from the irradiation pattern used when forming the second groove structure 120. In this example, the bottom of the second groove structure 120 is intermittently irradiated with a laser beam along a fourth direction (indicated by a double-headed arrow d4 in FIG. 17) intersecting the third direction described above. A plurality of second recesses 123d aligned in the direction are formed at the bottom of the second groove structure 120. The fourth direction may be a direction parallel to any one of the above-mentioned first direction, second direction, and third direction. Alternatively, the fourth direction may be a direction different from any of the first direction, the second direction, and the third direction.

Here, the irradiation conditions such as laser output in the step of forming the second recess 123d may be the same as the laser light irradiation conditions when forming the first recess 111d on the upper surface 100a side of the base 100S. It's okay and it can be different. Further, here, similar to the first recesses 111d on the upper surface 100a side of the base 100S, a plurality of second recesses 123d are arranged in a triangular lattice shape at the bottom of the second groove structure 120, but a plurality of second recesses 123d are arranged at the bottom of the second groove structure 120. Of course, the number and arrangement of the recesses 123d are arbitrary. Note that the pitch of the plurality of third grooves 123 described above may be in a range of, for example, 10% or more and 100% or less with respect to the distance between the centers of the two second recesses 123d. The plurality of second recesses 123d may include a plurality of recesses having different depths.

(Second wiring pattern formation step (F))
Next, the second trench structure is filled with a second conductive material to form a second wiring pattern from the second conductive material (step S6 in FIG. 14). As schematically shown in FIG. 18, the second groove structure 120 is filled with the second conductive material by printing using a squeegee 190, for example. Note that FIG. 18 is a diagram schematically showing an enlarged cross section of a part of the base 100S, and in FIG. 18, for ease of understanding, the first groove structure 110 and , shows an example of a cross section when the base 100S is cut at a position where the second groove structure 120 on the lower surface 100b side overlaps.

The second conductive material may be the same as the first conductive material described above, or may be different from the first conductive material. Here, the above-mentioned conductive paste 130r is used as the second conductive material. By moving the squeegee 190 on the lower surface 100b of the base 100S, the position of the surface 130rb of the conductive paste 130r on the lower surface 100b side of the base 100S can be approximately aligned with the lower surface 100b of the base 100S. When placing the conductive paste 130r in the second groove structure 120, the inside of the third groove 123 and the inside of the second recess 123d are filled with the conductive paste 130r. Of course, the method of applying the conductive paste 130r to the base 100S is not limited to the printing method.

As understood from FIG. 18, the second groove structure 120 includes a second bottom surface 120b formed by a set of a plurality of third grooves 123. By irradiating one or more of the third grooves 123 with laser light, a portion of the second bottom surface 120b can be further removed, and a plurality of second recesses 123d can be formed in the second bottom surface 120b as deeper portions. Here, the second groove structure 120 may have a depth in a range of, for example, approximately 5 μm or more and 50 μm or less. The depth Dp2 of the second groove structure 120 is defined as the distance from the position of the plurality of tops formed between two mutually adjacent third grooves 123 to the lower surface 100b of the base 110S.

Next, the second conductive material placed inside the second groove structure 120 is cured by heating or light irradiation. Here, by curing the conductive paste 130r as the second conductive material, as schematically shown in FIG. The second wiring pattern 132 having a shape matching the shape can be formed from the conductive paste 130r.

After the conductive paste 130r is hardened, if necessary, a polishing step of polishing the surface of the hardened conductive paste 130r and the lower surface 100b of the base 100S may be additionally performed in the same manner as the example shown in FIG. good. By polishing, the surface 132b of the second wiring pattern 132 can be aligned with the lower surface 100b of the base 100S, as schematically shown in FIG. 20.

Through the above steps, a wiring board 100C having the first wiring pattern 131 on the upper surface 100a side and the second wiring pattern 132 on the lower surface 100b side is obtained.

According to this embodiment, the second wiring pattern 132 having an arbitrary shape can also be formed on the lower surface 100b side of the base 100S by a relatively simple process. Like the first groove structure 110, the second groove structure 120 is formed by laser beam irradiation, so a high degree of freedom is obtained regarding the shape of the second wiring pattern 132, and wiring can be formed in the form of highly accurate thin lines. is also relatively easy. Further, wiring with a high aspect ratio can be realized. That is, according to the present embodiment, it is possible to provide a wiring board having a fine wiring pattern with a high aspect ratio on both sides of the base 100S through a relatively simple process.

In the example shown in FIG. 20, the surface (upper surface 131a) of the first wiring pattern 131 is aligned with the upper surface 100a of the base 100S, and the surface 132b of the second wiring pattern 132 is also aligned with the lower surface 100b of the base 100S. are doing. In this way, according to the present embodiment, a thinner double-sided board is provided in which the wiring does not protrude from the surface of the base 100S.

Furthermore, in this embodiment, similarly to the formation of the first wiring pattern 131 on the upper surface 100a side of the base 100S, the second groove structure 120 is formed on the lower surface 100b side of the base 100S after the second groove structure 120 is formed. The inside of the second groove structure 120 is further irradiated with laser light using an irradiation pattern different from the irradiation pattern in the formation process. Thereby, a further uneven shape can be provided to the second bottom surface 120b including the plurality of third grooves 123. For example, as described with reference to FIG. 17, a plurality of dot-shaped second recesses 123d may be formed on the second bottom surface 120b. For example, by forming a deeper portion in the form of a plurality of second recesses 123d on the second bottom surface 120b, the area of the interface between the second wiring pattern 132 and the base 100S increases, and a stronger anchoring effect can be obtained. That is, peeling of the second wiring pattern 132 from the base 100S is suppressed, and the reliability of the wiring board can be further improved.

(Modified example)
Similar to the example described with reference to FIGS. 9 to 12 regarding the formation of the first wiring pattern 131, by further irradiating the second bottom surface 120b of the second groove structure 120 with laser light, a dot-like pattern is formed on the second bottom surface 120b. Instead of forming a plurality of second recesses 123d, a plurality of fourth grooves may be formed as described below.

FIG. 21 schematically shows a state after forming the second groove structure 120 and irradiating the inside of the second groove structure 120 with a laser beam LB using an irradiation pattern different from that used when forming the second groove structure 120. Shown below. In the example shown in FIG. 21, for example, by scanning along the fourth direction described above, a plurality of fourth grooves 124, each extending in the fourth direction, similar to the third groove 123 are formed inside the second groove structure 120. More are forming. Here, a direction different from the third direction is selected as the fourth direction. That is, each of the plurality of fourth grooves 124 extends in a different direction from the plurality of third grooves 123.

FIG. 22 shows an enlarged cross-section of a part of the base 100S shown in FIG. 21. The fourth direction in irradiation, which is the scanning direction of the laser beam LB to the second bottom surface 120b of the second groove structure 120, is a direction different from the third direction in which the plurality of third grooves 123 extend. In this example, the second bottom surface 120b is partially removed by further irradiating the second bottom surface 120b of the second groove structure 120 with laser light, and as a result, a plurality of fourth grooves 124 are formed in the second bottom surface 120b. There is.

As schematically shown in FIG. 22, each of the plurality of fourth grooves 124 has a sixth width W6. The sixth width W6 is smaller than the fourth width W4 of the second groove structure 120 (see FIG. 15). Setting values such as laser output and pulse intervals in the step of forming the plurality of fourth grooves 124 may be the same as or different from the setting values in the step of forming the plurality of third grooves 123. The arrangement pitch of the fourth grooves 124 may also be the same as or different from the arrangement pitch of the third grooves 123.

By forming the plurality of fourth grooves 124 overlapping the plurality of third grooves 123, a deeper portion is formed at the position where the third grooves 123 and the fourth grooves 124 intersect. These relatively deep portions may be dot-shaped recesses similar to the plurality of second recesses 123d. Hereinafter, these deeper portions may be referred to as "second recessed portions 124d" for convenience.

FIG. 23 schematically shows a state in which a second wiring pattern is formed from the state shown in FIG. 22. By filling the inside of the second groove structure 120 with the second conductive material in the same manner as in the example described with reference to FIG. can be formed.

The wiring board 100D shown in FIG. 23 has a second wiring pattern 132 arranged in the second groove structure 120 on the lower surface 100b side of the base 100S, like the wiring board 100C described above. As in this example, by forming a plurality of fourth grooves 124 that intersect with a plurality of third grooves 123 by irradiating a laser beam with a different irradiation pattern than when forming a plurality of third grooves 123, a plurality of fourth grooves 124 are formed. A plurality of second recesses 124d may be further formed inside the two-groove structure 120. By forming a plurality of fourth grooves 124 overlapping the plurality of third grooves 123 instead of forming a plurality of dot-shaped second recesses 123d, fine wiring with a high aspect ratio can be formed on both sides of the base 100S. A wiring board having a pattern and improved reliability can be provided.

By forming the plurality of second recesses 124d, a part of the second wiring pattern 132 can be located not only inside the plurality of third grooves 123 and fourth groove 124 but also inside the second recesses 124d. Therefore, by further forming a plurality of fourth grooves 124 that are thinner than the second groove structure 120 on the second bottom surface 120b of the second groove structure 120, the area of the interface between the second wiring pattern 132 and the base 100S increases. , the anchor effect is further improved. Thereby, the effect of suppressing peeling of the second wiring pattern 132 from the base 100S and improving the reliability of the wiring board can be expected.

FIG. 24 shows a further modification of the wiring board according to Embodiment 2 of the present disclosure. The wiring board 100E shown in FIG. 24 includes a base 100S having a first groove structure 110 and a second groove structure 120 on the upper surface 100a side and the lower surface 100b side, respectively, and a first wiring arranged inside the first groove structure 110. It includes a pattern 131, a second wiring pattern 132 arranged inside the second groove structure 120, and at least one via 150 formed inside the base 100S.

In the configuration illustrated in FIG. 24, the first groove structure 110 has a first bottom surface 110b configured by a set of a plurality of first grooves 111, and the first bottom surface 110b has a wiring board 100A shown in FIG. A plurality of first recesses 111d are formed similarly to the example. Further, the second groove structure 120 has a second bottom surface 120b configured by a set of a plurality of third grooves 123, and the second bottom surface 120b has a plurality of third grooves 123, as in the example of the wiring board 100C shown in FIG. A second recess 123d is formed.

As schematically shown in FIG. 24, one end of the via 150 is connected to the first wiring pattern 131 on the upper surface 100a side of the base 100S, and the other end of the via 150 is connected to the second wiring pattern 131 on the lower surface 100b side. 132. That is, the via 150 penetrating the base 100S electrically connects the first wiring pattern 131 and the second wiring pattern 132 to each other. Note that in FIG. 24, only one via 150 is shown in order to avoid overly complicating the drawing, but the number of vias 150 and their arrangement are arbitrary. The cross-sectional shape of the via 150 when the wiring board is cut parallel to the upper surface 100a or the lower surface 100b is not limited to a specific shape.

As already explained, in the embodiment of the present disclosure, the first groove structure 110 and the second groove structure 120 are formed by scanning the laser beam LB, and have a high degree of freedom in shape in plan view. . In addition, the first wiring pattern 131 formed in the first trench structure 110 and the second wiring pattern 132 formed in the second trench structure 120 correspond to the first trench structure 110 and the second trench structure 120, respectively. It is formed in a plan view shape. That is, by appropriately determining the laser beam irradiation pattern, it is possible to easily obtain the first wiring pattern 131 and the second wiring pattern 132 having any shape in plan view. Therefore, according to the present embodiment, the base has wiring patterns of arbitrary shapes on both sides and a conductive path connecting these wiring patterns inside the base, while avoiding complication of the process. It is possible to provide an interposer.

An exemplary method for manufacturing wiring board 100E shown in FIG. 24 will be outlined below. First, the first wiring pattern 131 is formed on the upper surface 100a side of the base 100S in the same manner as in the example described with reference to FIGS. 2 to 7. Next, the second groove structure 120 is formed on the lower surface 100b side of the base 100S, for example, in the same manner as in the example described with reference to FIGS. 15 and 16. FIG. 25 schematically shows the base 100S in which the second groove structure 120 is provided.

(Through hole formation step (G))
Next, by irradiating laser light, a through hole is formed that connects the first groove structure 110 on the upper surface 100a side of the base 100S and the second groove structure 120 on the lower surface 100b side. For example, if a CO ₂ laser is used, the output of the laser is increased compared to when forming the plurality of third grooves 123, and the second bottom surface 120b is irradiated with the laser beam LB, as shown schematically in FIG. As shown in , a through hole 150p reaching the first groove structure 110 from the second bottom surface 120b can be formed inside the base 100S. Alternatively, when using a YAG laser, the through hole 150p is formed by processing such as moving the laser spot in a circular manner around the center of the area where the through hole 150p is to be formed on the second bottom surface 120b. It is possible. The through holes 150p may be provided at any position as long as the first groove structure 110 and the second groove structure 120 overlap when viewed from above, and the number of through holes 150p may also be determined arbitrarily.

Next, the second irradiation step (E) described above is performed. That is, by further irradiating the inside of the second groove structure 120 with a laser beam in the same manner as in the example described with reference to FIG. do. FIG. 27 schematically shows the base 100S in which a plurality of second recesses 123d are provided on the second bottom surface 120b. Note that instead of the plurality of second recesses 123d, a plurality of fourth grooves 124 intersecting the plurality of third grooves 123 are formed in the second bottom surface 120b, as in the example described with reference to FIGS. 21 and 22. By doing so, a plurality of second recesses 124d may be formed at the intersections of the third groove 123 and the fourth groove 124. Further, here, an example is shown in which a plurality of first recesses 111d are provided in the bottom of the first groove structure 110, but instead of the plurality of first recesses 111d, a plurality of second grooves 112 are provided in the first bottom surface. 110b, a plurality of first recesses 112d may be formed at the intersections of the first grooves 111 and the second grooves 112. In this way, the various configurations shown in this specification can be arbitrarily combined as long as there is no technical inconsistency.

Next, the above-described second wiring pattern forming step (F) is performed. However, here, the second conductive material is disposed not only inside the second groove structure 120 but also inside the through hole 150p. In the example shown in FIG. 28, the second groove structure 120 and the through hole 150p are filled with a conductive paste 130r as the second conductive material by printing using a squeegee 190. According to a method called a vacuum printing method in which filling is performed while performing evacuation, the conductive paste 130r can be filled into the through hole 150p while suppressing the inclusion of air bubbles. In this step, the conductive paste 130r typically occupies the entire space defined by the inner surface of the through hole 150p, as shown in FIG. However, the present invention is not limited to this example, and as schematically shown in FIG. 29, the conductive paste 130r may be selectively applied to the inner surface of the through hole 150p. In this case, the space inside the cylindrical conductive paste 130r film formed in the through hole 150p may be filled with resin or the like.

Next, the conductive paste 130r as the second conductive material placed inside the second groove structure 120 and the through hole 150p is hardened. By hardening the conductive paste 130r, a via 150 is formed from a portion of the conductive paste 130r located inside the through hole 150p, and the first wiring pattern 131 on the top surface 100a side of the base 100S is connected to the second wiring pattern on the bottom surface 100b side. The pattern 132 can be connected by vias 150. Through the above steps, a wiring board 100E shown in FIG. 24 is obtained.

According to the example described here, a conductive path between the upper surface 100a side and the lower surface 100b side of the base 100S can be formed relatively easily. The first wiring pattern 131 on the upper surface 100a side of the base 100S and the second wiring pattern 132 on the lower surface 100b side are not only electrically connected by the via 150 but also physically coupled, so the via By forming 150, peeling of the wiring pattern from the base can be more effectively suppressed. That is, it is possible to provide a double-sided board in which peeling of the wiring pattern from the base is suppressed while avoiding complication of the process.

In the example described here, the step of forming the through hole 150p is performed between the above-described second groove structure forming step (D) and the second irradiation step (E). However, the timing of performing the step of forming the through hole is not limited to this example. For example, the step of forming the through hole may be performed simultaneously with the second groove structure forming step (D) for forming the plurality of third grooves 123 that constitute the second bottom surface 120b of the second groove structure 120. However, it may be performed after forming the plurality of second recesses 123d or the plurality of fourth grooves 124. Alternatively, as shown in FIG. 30, a through hole may be formed in the base 100S in advance by laser processing, punching, processing using an NC lathe, etc. before forming the second groove structure 120. The processing method applied to forming the through hole may be appropriately selected depending on the material of the base 100S.

In the example shown in FIG. 30, one opening of the through hole 150q extending from the first bottom surface 110b of the first groove structure 110 toward the lower surface 100b of the base 100S is located on the lower surface 100b of the base 100S. The conductive material may be placed inside the through hole 150q at the stage of filling the first groove structure 110 with the first conductive material, or the second conductive material may be placed inside the second groove structure 120. It may also be carried out at the stage of filling the material.

When a ceramic substrate is used as the base 100S, a through hole connecting the front and back surfaces of the green sheet may be formed by punching or the like in the green sheet before firing. It is also possible to prepare a base in which vias are formed in advance and form the first groove structure 110 on this base, or to form vias in the base 100S in advance before forming the first groove structure 110. It may be formed in advance. In this case, a portion of the via may be removed by irradiation with laser light.

Hereinafter, a wiring board according to an embodiment of the present disclosure will be described in more detail using Examples. Of course, embodiments of the present disclosure are not limited to the forms specified by the following examples.

(Evaluation 1 regarding the shape of the bottom of the groove structure)
A groove structure was formed on one main surface of the resin plate by scanning a laser beam on a white resin plate, and the bottom of the groove structure was further irradiated with laser light by changing the irradiation pattern to create multiple samples. The shape of the bottom of the groove structure was evaluated for the sample.

(Example 1-1)
First, a resin plate was prepared in which titanium dioxide particles were dispersed in a silicone resin as a base material. Next, by scanning a laser beam in a certain direction (first direction) on one main surface of this resin plate, a plurality of first grooves each extending along the first direction are formed in the resin plate. (corresponding to the first groove structure forming step described above). Here, by scanning the laser beam on five different regions on the main surface of the resin plate, five regions each having a first bottom surface defined by a set of a plurality of first grooves are formed. A first groove structure including a portion was formed in a resin plate. The laser beam irradiation conditions at this time are shown below.
Peak wavelength of laser light: 532nm
Laser power: 2.4W
Pulse width: 100 nanoseconds Frequency: 50kHz
Feed speed: 200mm/s
Defocus: 0μm
First groove pitch: 15μm or 30μm

Next, from among the five portions included in the first groove structure, one in which the pitch of the first groove is 15 μm is selected at random, and a beam of laser light is directed in a second direction intersecting the first direction. After scanning, the bottom of the selected portion (hereinafter referred to as the first portion) was irradiated with a laser beam (corresponding to the first irradiation step described above). As a result, a plurality of dot-shaped first recesses were formed at the bottom of the first portion, similar to the examples shown in FIGS. 4 and 5, and a sample of Example 1-1 was obtained. Note that here, a direction perpendicular to the first direction was selected as the second direction. When viewed from above, each first recess had a diameter of approximately 0.1 mm. The laser beam irradiation conditions at this time are shown below.
Peak wavelength of laser light: 532nm
Laser power: 2.4W
Pulse width: 100 nanoseconds Frequency: 50kHz
Feed speed: 200mm/s
Defocus: 0μm
Distance between centers of first recess: 15μm

FIG. 31 is a microscope image showing an enlarged first bottom surface of the sample of Example 1-1. FIG. 32 shows a cross-sectional profile of the sample of Example 1-1 obtained by a laser microscope, and corresponds to the XXXII-XXXII cross-sectional view of FIG. 31. The horizontal white dashed line in FIG. 32 indicates the position of the surface of the resin plate before the first groove structure is formed. As shown in FIG. 31, here, three first recesses are formed in the bottom of the first portion in a row in the horizontal direction of the page. The average depth of the three first recesses in the cross-sectional profile shown in FIG. 32 was approximately 120 μm.

(Example 1-2)
Among the five portions included in the first groove structure, the other one in which the pitch of the first groove is 15 μm is randomly selected, and the laser output is set to 1.2 W among the laser beam irradiation conditions. The bottom of the portion selected here (hereinafter referred to as the second portion) was exposed to laser light in the same manner as in Example 1-1 except that the frequency was changed so that the distance between the centers of the recesses was 60 μm. irradiated with a beam. As a result, a plurality of dot-shaped first recesses were formed at the bottom of the second portion, resulting in a sample of Example 1-2.

FIG. 33 is a microscope image showing an enlarged first bottom surface of the sample of Example 1-2. FIG. 34 shows a cross-sectional profile of the sample of Example 1-2 obtained by a laser microscope, and corresponds to the XXXIV-XXXIV cross-sectional view of FIG. 33. Similar to FIG. 32, the horizontal white dashed line in FIG. 34 indicates the position of the surface of the resin plate before the first groove structure is formed. Although it is difficult to confirm from FIG. 33, three first recesses are formed here along the XXXIV-XXXIV line, similar to the example shown in FIG. 31. The average depth of the three first recesses in the cross-sectional profile shown in FIG. 34 was approximately 50 μm.

(Example 1-3)
Among the five parts included in the first groove structure, one where the pitch of the first groove is 30 μm is randomly selected, and the distance between the centers of the first recesses is set to 30 μm under the laser beam irradiation conditions. The bottom of the selected portion (hereinafter referred to as the third portion) was irradiated with a laser beam in the same manner as in Example 1-2 except that the frequency was changed to . As a result, a plurality of dot-shaped first recesses were formed at the bottom of the third portion, and a sample of Example 1-3 was obtained.

FIG. 35 is a microscope image showing an enlarged view of the first bottom surface of the sample of Example 1-3. FIG. 36 shows a cross-sectional profile of the sample of Examples 1-3 obtained by a laser microscope, and corresponds to the XXXVI-XXXVI cross-sectional view of FIG. 35. The horizontal white dotted line in FIG. 36 indicates the position of the surface of the resin plate before the first groove structure is formed. Although it is difficult to confirm from FIG. 35, three first recesses are formed along the XXXVI-XXXVI line in this example as well, as in the examples shown in FIGS. 31 and 33. The average depth of the three first recesses in the cross-sectional profile shown in FIG. 36 was approximately 40 μm.

(Example 1-4)
Among the five parts included in the first groove structure, the other one in which the pitch of the first groove is 30 μm is selected at random, and under the laser beam irradiation conditions, the center-to-center distance of the first recess is 60 μm. The bottom of the portion selected here (hereinafter referred to as the fourth portion) was irradiated with a laser beam in the same manner as in Example 1-3, except that the frequency was changed so that the results were as follows. As a result, a plurality of dot-shaped first recesses were formed at the bottom of the fourth portion, resulting in a sample of Example 1-4.

FIG. 37 is a microscope image showing an enlarged first bottom surface of the sample of Example 1-4. FIG. 38 shows a cross-sectional profile of the samples of Examples 1-4 obtained by a laser microscope, and corresponds to the XXXVIII-XXXVIII cross-sectional view of FIG. 37. The horizontal white dotted line in FIG. 38 indicates the position of the surface of the resin plate before the first groove structure is formed. Although it is difficult to confirm from FIG. 37, three first recesses are formed along the XXXVIII-XXXVIII line in this example as well, similar to the examples shown in FIGS. 31, 33, and 35. The average depth of the three first recesses in the cross-sectional profile shown in FIG. 38 was approximately 38 μm.

(Reference example 1-1)
Among the laser beam irradiation conditions, the remaining one (hereinafter, the The bottom part (referred to as section 5) was irradiated with a beam of laser light. As a result, a plurality of dot-shaped first recesses were formed at the bottom of the fifth portion, and a sample of Reference Example 1-1 was obtained.

FIG. 39 is a microscope image showing an enlarged view of the first bottom surface of the sample of Reference Example 1-1. FIG. 40 shows a cross-sectional profile of the sample of Reference Example 1-1 obtained by a laser microscope, and corresponds to the XL-XL cross-sectional view of FIG. 39. The horizontal white dotted line in FIG. 40 indicates the position of the surface of the resin plate before the first groove structure is formed. Although it is difficult to confirm from FIG. 39, three first recesses are formed along the XL-XL line in this example as well, similar to the examples shown in FIGS. 31, 33, 35, and 37. The average depth of the three first recesses in the cross-sectional profile shown in FIG. 40 was approximately 22 μm.

From the cross-sectional profiles for each sample of Examples 1-1 to 1-4 (FIGS. 32, 34, 36, and 38) and the cross-sectional profile for the sample of Reference Example 1-1 (FIG. 40), it is found that It was found that the plurality of peaks formed between the two first grooves were located at a lower position than the surface of the resin plate before the first groove structure was formed. That is, in these samples, the position of the first bottom surface is lower than the surface of the resin plate before the formation of the first groove structure. Therefore, when the first conductive material is placed inside the first groove structure, the first conductive material is not only located at the bottom of the first groove structure, but also at the first groove structure located between the bottom and the surface of the resin plate. Since it also comes into contact with the side surface, it is expected that an anchor effect will be exerted at the interface between the side surface of the first groove structure and the first conductive material.

As can be seen by comparing the cross-sectional profiles of each sample of Examples 1-1 to 1-4 and the cross-sectional profile of the sample of Reference Example 1-1, the sample of Reference Example 1-1 is No large irregularities were formed in the irradiated area. That is, when forming a plurality of dot-shaped first recesses on the first bottom surface in the first irradiation step, from the viewpoint of forming the first recesses with an appropriate depth on the first bottom surface, the feed rate should not be made extremely high. I found that to be beneficial. In addition, from a comparison of the cross-sectional profile of the sample of Example 1-1 and the cross-sectional profile of each sample of Examples 1-2 to 1-4, it was found that if the feed rate is the same, the laser output can be controlled within a certain range. It was found that it is easier to obtain finer irregularities by suppressing the shape.

(Evaluation 1 of shape of first wiring pattern)
Next, a first wiring pattern is formed in the first groove structure by filling the first groove structure with conductive paste and curing the conductive paste (corresponding to the first wiring pattern forming step described above), and by cross-sectional observation. It was investigated whether the first wiring pattern had a shape that followed the shape of the bottom of the first trench structure.

(Example 1-5)
The second portion of the sample of Example 1-2 was filled with conductive paste and the conductive paste was cured to produce the sample of Example 1-5 according to the following procedure. Here, first, the second part is filled with conductive paste using a printing method using a squeegee, and then the conductive paste is cured by placing the resin plate filled with conductive paste at a temperature of 130°C for 30 minutes. In this way, a first wiring pattern was formed inside the second portion.

FIG. 41 is a microscopic image showing the second portion before filling with conductive paste. A plurality of first grooves and a plurality of first recesses running diagonally on the plane of the paper can be confirmed. FIG. 42 shows a cross section after the second portion is filled with conductive paste and the conductive paste is cured. In the following description, the cross-sectional view of the conductive paste after it has been cured shows a cross-section of approximately 4 mm square.

(Example 1-6)
A sample of Example 1-6 was prepared in the same manner as the sample of Example 1-5 except that the third portion of the sample of Example 1-3 was filled with conductive paste. FIG. 43 is a microscope image showing the third portion before filling with conductive paste. FIG. 44 shows a cross section after the third portion is filled with conductive paste and the conductive paste is cured.

(Example 1-7)
A sample of Example 1-7 was prepared in the same manner as the sample of Example 1-5 except that the fourth portion of the sample of Example 1-4 was filled with conductive paste. FIG. 45 is a microscope image showing the fourth portion before filling with conductive paste. FIG. 46 shows a cross section after the fourth portion is filled with conductive paste and the conductive paste is cured.

From the cross-sectional images (FIGS. 42, 44, and 46) of each sample of Examples 1-5 to 1-7, it is clear that a part of the first wiring pattern is located in the first groove and the first recess in each sample. It was found that it was inside the . That is, the first wiring pattern closely followed the shape of the bottom of the first trench structure, and no voids were generated between the first wiring pattern and the bottom of the first trench structure.

(Evaluation 2 regarding the shape of the bottom of the groove structure)
Instead of forming a plurality of dot-shaped first recesses in the first irradiation step, the bottom of the first groove structure is irradiated with laser light by scanning the laser light beam in a second direction different from the first direction. By doing so, a plurality of samples each having a plurality of second grooves extending in the second direction were produced at the bottom of the first groove structure. These samples were evaluated regarding the shape of the bottom of the first groove structure.

(Example 2-1)
First, in the same manner as in the preparation of the sample of Example 1-1 above, a first groove structure including five parts each having a first bottom surface defined by a set of a plurality of first grooves is formed on a resin plate. Formed. However, here, the laser beam irradiation conditions are changed as appropriate so that the pitch of the first grooves is 50 μm. Hereinafter, these five parts will be referred to as the 6th part to the 10th part.

Next, the laser beam was scanned in a second direction intersecting the first direction, and the bottom of the sixth portion of the first groove structure was irradiated with the laser beam (corresponding to the first irradiation step described above). ). As a result, like the example shown in FIG. 9, a plurality of second grooves each extending in the second direction were formed at the bottom of the sixth portion, overlapping the first grooves, and a sample of Example 2-1 was obtained. Note that here as well, a direction perpendicular to the first direction is selected as the second direction. The laser beam irradiation conditions at this time are shown below.
Peak wavelength of laser light: 532nm
Laser power: 2.4W
Pulse width: 100 nanoseconds Frequency: 50kHz
Feed speed: 200mm/s
Defocus: 0μm
Pitch of second groove: 50μm

FIG. 47 is a microscope image showing an enlarged view of the first bottom surface of the sample of Example 2-1. Figure 4
8 shows a cross-sectional profile of the sample of Example 2-1 obtained by a laser microscope, and corresponds to the XLVIII-XLVIII cross-sectional view in FIG. 47. The horizontal white dotted line in FIG. 48 indicates the position of the surface of the resin plate before the first groove structure is formed. As shown in FIG. 48, here, eight first recesses were formed at the bottom of the sixth portion along the horizontal direction of the page. The average depth of the eight first recesses in the cross-sectional profile shown in FIG. 48 was approximately 50 μm.

(Example 2-2)
The bottom of the seventh portion of the first groove structure was irradiated with a laser beam in the same manner as in Example 2-1 except that the laser output was 1.2 W among the laser beam irradiation conditions. As a result, a plurality of second grooves, each extending in the second direction, were formed at the bottom of the seventh portion, overlapping the first grooves, and a sample of Example 2-2 was obtained.

FIG. 49 is a microscope image showing an enlarged first bottom surface of the sample of Example 2-2. FIG. 50 shows a cross-sectional profile of the sample of Example 2-2 obtained by a laser microscope, and corresponds to the LL cross-sectional view of FIG. 49. Similar to FIG. 48, the horizontal white dashed line in FIG. 50 indicates the position of the surface of the resin plate before the first groove structure is formed. Also in this example, like the example shown in FIG. 48, eight first recesses were formed along the LL line. The average depth of the eight first recesses in the cross-sectional profile shown in FIG. 50 was approximately 35 μm.

(Example 2-3)
The bottom of the eighth portion of the first groove structure was irradiated with a laser beam in the same manner as in Example 2-1 except that the laser output was 1.6 W among the laser beam irradiation conditions. As a result, a plurality of second grooves, each extending in the second direction, were formed at the bottom of the eighth portion, overlapping the first grooves, and a sample of Example 2-3 was obtained.

FIG. 51 is a microscope image showing an enlarged view of the first bottom surface of the sample of Example 2-3. FIG. 52 shows a cross-sectional profile of the sample of Example 2-3 obtained by a laser microscope, and corresponds to the LII-LII cross-sectional view of FIG. 51. The horizontal white dotted line in FIG. 52 indicates the position of the surface of the resin plate before the first groove structure is formed. Similarly to the examples shown in FIGS. 48 and 50, eight first recesses were formed along the LII-LII line in this example as well. The average depth of the eight first recesses in the cross-sectional profile shown in FIG. 52 was approximately 37 μm.

(Example 2-4)
The bottom of the ninth portion of the first groove structure was irradiated with a laser beam in the same manner as in Example 2-1 except that the laser output was 2 W among the laser beam irradiation conditions. As a result, a plurality of second grooves, each extending in the second direction, were formed at the bottom of the ninth portion, overlapping the first grooves, and a sample of Example 2-4 was obtained.

FIG. 53 is a microscope image showing an enlarged first bottom surface of the sample of Example 2-4. FIG. 54 shows a cross-sectional profile of the sample of Example 2-4 obtained by a laser microscope, and corresponds to the LIV-LIV cross-sectional view of FIG. 53. The horizontal white dotted line in FIG. 54 indicates the position of the surface of the resin plate before the first groove structure is formed. Similarly to the examples shown in FIGS. 48, 50, and 52, eight first recesses were formed along the LIV-LIV line in this example as well. The average depth of the eight first recesses in the cross-sectional profile shown in FIG. 54 was approximately 42 μm.

(Reference example 2-1)
The bottom of the 10th portion of the first groove structure was irradiated with a laser beam in the same manner as in Example 2-1 except that the feed speed was 500 mm/s among the laser beam irradiation conditions. As a result, a plurality of second grooves, each extending in the second direction, were formed at the bottom of the tenth portion, overlapping the first grooves, and a sample of Reference Example 2-1 was obtained.

FIG. 55 shows a cross-sectional profile of the sample of Reference Example 2-1 obtained by a laser microscope. The horizontal white dotted line in FIG. 55 indicates the position of the surface of the resin plate before the first groove structure is formed. Similarly to the examples shown in FIGS. 48, 50, 52, and 54, in this example as well, the formation of eight first recesses was confirmed in the cross-sectional view. The average depth of the eight first recesses in the cross-sectional profile shown in FIG. 55 was approximately 30 μm.

From the cross-sectional profiles of each sample of Examples 2-1 to 2-4 (FIGS. 48, 50, 52, and 54), the results of Examples 1-1 to 1-4 and Reference Example 1-1 are Similarly to the samples, in these samples as well, the plurality of peaks formed between two first grooves adjacent to each other may be located at a lower position than the surface of the resin plate before the first groove structure is formed. Understood. Therefore, these samples are also expected to exhibit an anchoring effect at the interface between the side surface of the first groove structure and the first conductive material.

On the other hand, referring to the cross-sectional profile (FIG. 55) regarding the sample of Reference Example 2-1, in the sample of Reference Example 2-1, the position of the first bottom surface is the surface of the resin plate before the formation of the first groove structure. The position roughly corresponds to that of . This means that it is relatively difficult to form a first wiring pattern with a large aspect ratio. From this, it can be said that from the viewpoint of arranging the first conductive material inside the first groove structure and forming the first wiring pattern from the first conductive material, it is beneficial not to increase the feeding speed extremely.

(Evaluation of shape of first wiring pattern 2)
Next, regarding the configuration in which a plurality of first grooves and second grooves were provided at the bottom of the first groove structure, it was investigated whether the first wiring pattern had a shape that followed the shape of the bottom of the first groove structure. .

(Example 2-5)
In the same manner as the sample of Example 1-5, the sixth portion of the first groove structure was filled with conductive paste and the conductive paste was cured. As a result, a sample of Example 2-5 having the first wiring pattern formed from the conductive paste inside the sixth portion was obtained.

FIG. 56 is a microscope image showing the sixth portion before filling with conductive paste. In FIG. 56, it appears that a plurality of zigzag grooves are formed at the bottom of the first groove structure, but in reality, the plurality of first grooves are formed by scanning a laser beam along the first direction. , and forming a plurality of second grooves by scanning the laser beam along the second direction. Double-headed arrow d1 and double-headed arrow d2 in FIG. 56 represent the first direction and the second direction, respectively. FIG. 57 shows a cross section after the sixth portion is filled with conductive paste and the conductive paste is cured. The white dotted line in FIG. 57 indicates the approximate position of the first bottom surface of the first groove structure.

(Example 2-6)
A sample of Example 2-6 was prepared in the same manner as the sample of Example 2-5 except that the eighth portion of the sample of Example 2-3 was filled with conductive paste. FIG. 58 is a microscope image showing the eighth portion before being filled with conductive paste. The point is that the formation of the plurality of first grooves by scanning the laser beam along the first direction and the formation of the plurality of second grooves by scanning the laser beam along the second direction are performed sequentially. , similar to the sample of Example 2-5. FIG. 59 shows a cross section after the eighth portion is filled with conductive paste and the conductive paste is cured. Similar to FIG. 57, the white dotted line in FIG. 59 indicates the approximate position of the first bottom surface of the first groove structure.

(Example 2-7)
A sample of Example 2-7 was prepared in the same manner as the sample of Example 2-5 except that the ninth portion of the sample of Example 2-4 was filled with conductive paste. FIG. 60 is a microscope image showing the ninth portion before being filled with conductive paste. Similar to the sample of Example 2-5 and the sample of Example 2-6, in this example as well, a plurality of first grooves are formed by scanning the laser beam along the first direction, and a plurality of first grooves are formed by scanning the laser beam along the first direction. The formation of a plurality of second grooves by scanning the laser beam along the grooves was sequentially performed. FIG. 61 shows a cross section after the ninth portion is filled with conductive paste and the conductive paste is cured. The white dotted line in FIG. 61 indicates the approximate position of the first bottom surface of the first groove structure.

From the cross-sectional images (FIGS. 57, 59, and 61) regarding each sample of Examples 2-5 to 2-7, it is clear that in all samples, a part of the first wiring pattern is located in the first groove and the second groove. It was found that it was inside the . That is, the first wiring pattern closely followed the shape of the bottom of the first trench structure, and no voids were generated between the first wiring pattern and the bottom of the first trench structure.

(Evaluation of adhesion of first wiring pattern)
Next, a simple evaluation of the adhesion of the first wiring pattern was conducted in the same manner as the evaluation of the mechanical properties of the coating film using a method similar to the cross-cut test specified in JIS K 5600-5-6 (1999). went.

(Example 3-1)
First, a first groove structure including seven rectangular portions having a first bottom surface defined by a set of a plurality of first grooves was formed on a resin plate. The laser beam irradiation conditions at this time are shown below.
Peak wavelength of laser light: 532nm
Laser power: 0.3W~2.8W
Pulse width: 100 nanoseconds Frequency: 50kHz
Feed speed: 200mm/s
Defocus: 0μm
First groove pitch: 15μm

Hereinafter, the seven parts formed here will be referred to as 11th to 17th parts. Here, the laser output was adjusted so that the depths of the first grooves were different between the 11th part to the 17th part. The laser output when forming the eleventh portion was 0.3W. The dimensions of the 11th to 17th portions when viewed from above were in the range of approximately 300 μm□ to 500 μm□.

Next, the laser beam was scanned in a second direction intersecting the first direction, and the bottom of the eleventh portion of the first groove structure was irradiated with the laser beam. As a result, like the example shown in FIG. 9, a plurality of second grooves, each extending in the second direction, were formed in the bottom of the eleventh portion, overlapping the first grooves. Note that here as well, a direction perpendicular to the first direction is selected as the second direction. The laser beam irradiation conditions at this time are shown below.
Peak wavelength of laser light: 532nm
Laser power: 0.3W
Pulse width: 100 nanoseconds Frequency: 50kHz
Feed speed: 200mm/s
Defocus: 0μm
Second groove pitch: 20μm
Note that, according to measurements using cross-sectional photography using a laser microscope, the average value of the depth of the second groove was approximately 5 μm.

Next, in the same manner as the sample of Example 1-5, the 11th portion of the first groove structure was filled with conductive paste and the conductive paste was cured. As a result, a sample of Example 3-1 having the first wiring pattern formed from the conductive paste inside the eleventh portion was obtained.

(Example 3-2)
In order to increase the depth of the first groove and the second groove, the conditions for laser beam irradiation were changed to 0.6 W, except that the laser output was changed to 0.6 W. A plurality of second grooves extending in the second direction were formed on the bottom of the twelfth portion, overlapping the first grooves. According to measurements using cross-sectional photography using a laser microscope, the average depth of the formed second grooves was approximately 10 μm.

Next, in the same manner as the sample of Example 3-1, the twelfth portion of the first groove structure was filled with conductive paste and the conductive paste was cured. As a result, a sample of Example 3-2 having the first wiring pattern formed from the conductive paste inside the twelfth portion was obtained.

(Example 3-3)
In order to increase the depth of the first groove and the second groove, the conditions for laser beam irradiation were changed to 1.2 W, except that the laser output was changed to 1.2 W. A plurality of second grooves extending in the second direction were formed at the bottom of the thirteenth portion so as to overlap the first grooves. According to measurements using cross-sectional photography using a laser microscope, the average depth of the formed second grooves was approximately 25 μm.

Next, in the same manner as the sample of Example 3-1, the 13th portion of the first groove structure was filled with conductive paste and the conductive paste was cured. As a result, a sample of Example 3-3 having the first wiring pattern formed from the conductive paste inside the thirteenth portion was obtained.

(Example 3-4)
In order to increase the depth of the first groove and the second groove, the conditions for laser beam irradiation were changed to 2.4 W, except that the laser output was changed to 2.4 W. A plurality of second grooves extending in the second direction were formed on the bottom of the fourteenth portion, overlapping the first grooves. According to measurements using cross-sectional photography using a laser microscope, the average depth of the second grooves formed was approximately 50 μm.

Next, in the same manner as the sample of Example 3-1, the 14th portion of the first groove structure was filled with conductive paste and the conductive paste was cured. As a result, a sample of Example 3-4 having the first wiring pattern formed from the conductive paste inside the fourteenth portion was obtained.

(Comparative example 3-1)
In forming the first grooves, each extending in the first direction was carried out in the same manner as in the sample of Example 3-1, except that the laser beam irradiation conditions were changed so that the depth of the first grooves became smaller. A 15th portion having a plurality of first grooves was formed. In forming the plurality of first grooves, the power was changed to 0.2W and the plurality of first grooves were formed here. Note that a plurality of second grooves are not formed here. According to measurements using cross-sectional photography using a laser microscope, the average value of the depth of the first groove was approximately 1.5 μm.

Next, in the same manner as the sample of Example 3-1, the 15th portion of the first groove structure was filled with conductive paste and the conductive paste was cured. As a result, a sample of Comparative Example 3-1 having the first wiring pattern formed from the conductive paste inside the 15th portion was obtained.

(Comparative example 3-2)
Similarly to the sample of Comparative Example 3-1, the conditions of laser light irradiation were changed so that the depth of the first groove was smaller than that of the sample of Example 3-1, and each A 16th portion having a plurality of first grooves extending thereinto was formed. In forming the plurality of first grooves, the power was changed to 0.2W and the plurality of first grooves were formed here.

Next, by scanning the laser beam in a second direction intersecting the first direction and irradiating the bottom of the 16th portion of the first groove structure with the laser beam, Similarly, a plurality of second grooves, each extending in the second direction, were formed on the bottom of the sixteenth portion, overlapping the first grooves. Note that here as well, a direction perpendicular to the first direction is selected as the second direction. The laser beam irradiation conditions at this time were the same as those for forming the first grooves, except that the laser output was 0.2 W and the pitch of the second grooves was 20 μm. Note that, according to measurements using cross-sectional photography using a laser microscope, the average value of the depth of the second groove was approximately 3 μm.

Next, in the same manner as the sample of Example 3-1, the 16th portion of the first groove structure was filled with conductive paste and the conductive paste was cured. As a result, a sample of Comparative Example 3-2 having the first wiring pattern formed from the conductive paste inside the 16th portion was obtained.

(Comparative example 3-3)
In forming the first grooves, each extending in the first direction was carried out in the same manner as in the sample of Example 3-1, except that the laser beam irradiation conditions were changed so that the depth of the first grooves became larger. A seventeenth portion having a plurality of first grooves was formed. In forming the plurality of first grooves, the power was changed to 2.8W and the plurality of first grooves were formed here.

Next, in the same manner as the sample of Comparative Example 3-2 except that the laser output was 2.8 W, the laser beam was scanned in a second direction intersecting the first direction to form the first groove structure. By irradiating the bottom of the 17th portion with a laser beam, a plurality of second grooves were formed in the bottom of the 17th portion, overlapping the first grooves. According to measurements using cross-sectional photography using a laser microscope, the average depth of the second grooves was approximately 60 μm.

Next, in the same manner as the sample of Example 3-1, an attempt was made to fill the inside of the 17th portion of the first groove structure with the conductive paste. However, the inside of the 17th portion was not sufficiently filled with the conductive paste, and although the conductive paste was cured, a wiring pattern of the desired shape could not be obtained.

Next, for each sample of Examples 3-1 to 3-4, Comparative Example 3-1, and Comparative Example 3-2, use a cutter to cut grooves that reach the first bottom surface in a grid pattern for the first wiring. By forming a pattern, a total of 25 rectangular sections were formed. At this time, grooves were formed in the first wiring pattern at a pitch of approximately 1 mm.

Next, apply cellophane tape to the surface of the first wiring pattern so as to cover the plurality of sections formed in the first wiring pattern. The tape was peeled off in the direction normal to the surface. At this time, out of the 25 sections formed in the first wiring pattern, the adhesion of the first wiring pattern was evaluated by examining the percentage of sections in which parts were peeled off from the resin plate due to adhesion to the tape side. evaluated.

In the sample of Example 3-1, peeling was confirmed in only one of the 25 sections, and in each of the samples of Examples 3-2 to 3-4, 25 sections were confirmed to have peeled off. No peeling was observed in any of the sections. On the other hand, in the sample of Comparative Example 3-1 and the sample of Comparative Example 3-2, the number of sections in which peeling was confirmed among 25 sections was 12.5 and 5, respectively.

FIG. 62 is a microscope image showing an enlarged first bottom surface of the sample of Example 3-3 before being filled with conductive paste. FIG. 63 shows the appearance of the first wiring pattern after the tape is peeled off regarding the sample of Example 3-3. FIG. 64 is a microscope image showing an enlarged first bottom surface of the sample of Comparative Example 3-1 before being filled with conductive paste. FIG. 65 shows the appearance of the first wiring pattern after the tape is peeled off regarding the sample of Comparative Example 3-2.

The results after peeling off the tape show that the formation of the second groove has the effect of preventing the first wiring pattern from falling off due to the anchor effect, and in particular, when the depth of the second groove is 5 μm or more, the first wiring pattern does not fall off. It was found that prevention is more advantageous. Furthermore, although there is a tendency that the deeper the second groove is, the greater the anchoring effect is obtained, it is important that the depth of the second groove does not exceed 60 μm to form the first wiring pattern in the desired shape. It also turned out to be advantageous.

The wiring board according to the embodiment of the present disclosure is useful in situations where printed wiring boards are used. The embodiments of the present disclosure are particularly suitable for high-density electronic components because it is relatively easy to form low-resistance wiring and it is also easy to form wiring patterns of arbitrary shapes on both sides of the board. is advantageous for implementation. Embodiments of the present disclosure are also applicable to manufacturing an interposer interposed between an electronic component and a wiring board.

100A to 100E Wiring board 100S Base 100a Top surface of the base 100b Bottom surface of the base 110 First groove structure 110b First bottom surface 111 First groove 111d, 112d First recess 112 Second groove 120 Second groove structure 120b Second bottom surface 123 Third groove 123d, 124d Second recess 124 Fourth groove 130r Conductive paste 131 First wiring pattern 132 Second wiring pattern 150 Via 150p, 150q Through hole 190 Squeegee 200 Grinding wheel 300 Laser ablation device 310 Laser light source 320 Galvano mirror

Claims (11)

By scanning a laser beam in a first direction to form a plurality of first grooves each extending in the first direction, a first width is formed on the first main surface of the base having a first main surface. a first groove structure forming step of forming a first groove structure having a first groove structure, wherein the first groove structure has a bottom defined by a set of the plurality of first grooves;
a first irradiation step of further irradiating the bottom of the first groove structure with a laser beam along a second direction perpendicular to the first direction;
The inside of the first groove structure is filled with a conductive paste by printing, the surface of the conductive paste is approximately aligned with the upper surface of the base, and a first wiring pattern is formed that matches the planar shape of the first groove structure. a first wiring pattern forming step of forming the conductive paste;
including;
The first irradiation step includes a first recess forming step of forming a plurality of dot-shaped first recesses on the bottom by further irradiating the set of first grooves with a laser beam,
The method for manufacturing a wiring board , wherein the plurality of first recesses are located deeper than the bottom surface of the first groove structure . 2. The method of manufacturing a wiring board according to claim 1, wherein the position of the bottom surface of the first groove structure generally corresponds to the position of a plurality of tops formed between the first grooves adjacent to each other. 3. The method for manufacturing a wiring board according to claim 1, wherein the depth from the first main surface of the base to the bottom surface of the first groove structure is 5 μm or more and 50 μm or less. Each of the plurality of first grooves formed in the first groove structure forming step has a second width smaller than the first width,
4. The method for manufacturing a wiring board according to claim 1, wherein the first recess has a diameter larger than the second width. Each of the plurality of first grooves formed in the first groove structure forming step has a second width smaller than the first width,
4. The method of manufacturing a wiring board according to claim 1 , wherein the pitch of the plurality of first grooves is in a range of 10% or more and 100% or less of a center-to-center distance of the first recesses. The method for manufacturing a wiring board according to any one of claims 1 to 5 , wherein the average depth of the plurality of first recesses is 35 μm or more and 120 μm or less. 7. The method for manufacturing a wiring board according to claim 1 , wherein the first irradiation step includes a step of intermittently irradiating the bottom portion with a laser beam. The method for manufacturing a wiring board according to claim 1 , wherein the plurality of first recesses are arranged in a triangular lattice shape. The method for manufacturing a wiring board according to any one of claims 1 to 8 , wherein the plurality of first recesses include recesses having different depths. The conductive paste is
At least one member selected from the group consisting of Au, Ag and Cu;
resin and
The method for manufacturing a wiring board according to any one of claims 1 to 9 , comprising: In the first wiring pattern forming step, the conductive paste follows the shape of the bottom of the first trench structure and creates a void between the bottom of the first trench structure and the first wiring pattern. The method for manufacturing a wiring board according to any one of claims 1 to 10 .

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