JP2002290046A - Wiring board and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent such a faultiness as a faulty disconnection and to realize the high reliability of such a wiring board as a printed wiring circuit board, by improving the state of the inside of its through hole. SOLUTION: In a manufacturing method of a wiring board, there are laminated and molded via prepregs boards in each of which wiring layers are provided on both the surfaces of an insulating base material and conductive layers having respectively circuit patterns, etc. A through hole is so formed in the obtained laminated body by using an NC drilling as to subject then it to a metal-plating. When forming the through hole, the circumferential speed of the NC drilling is so set as to be not higher than 150 m/min. and the feed speed of the NC drilling is so set as to be not higher than 1.0 m/min., and thereby, the metal- plated-off maximum roughness Rmax of the inner-wall surface of the through hole is so set as to be not larger than 50 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board used for mounting electronic components, and more particularly to a substrate for electronic components having excellent high-speed transmission and high-frequency characteristics.

[0002]

2. Description of the Related Art In recent years, IT such as Internet, LAN, etc.
Along with the related technical innovation, a large amount of data communication using an optical cable, digital wireless communication using a base station such as a mobile phone, and communication using a satellite have been widely used. In these data communications, since a large amount of data is transmitted and received, a higher frequency is required for an electronic device to be used. The electronic devices required for communication are diverse, such as routers, servers, LAN switches, etc. used for networks, PLL synthesizers used as electronic components, VCOs, BP filters, etc., and base stations and radars used for communication , Navigator, down converter, antenna and other electronic devices and components.

[0003] With the increase in the frequency of these electronic devices and the like, excellent high-frequency characteristics are also required for wiring boards. In addition, since it is necessary to mount a large number of components in order to increase the number of channels, there is a demand for a substrate that can sufficiently respond to the demands for higher density and multilayer wiring.

As a substrate having excellent high frequency characteristics, PTF
It is known to use a Teflon (registered trademark) resin represented by E or PPO for the insulating layer. However, in the case of using a Teflon-based resin substrate, if a through hole is formed for conduction between layers, it is difficult to make a hole, and in order to form a conductive layer by metal plating, processing of special chemicals such as metallic sodium is required. It was required and it was difficult to manufacture through-holes. In addition, when a resin such as polybutadiene and polyisoprene is used, although high frequency characteristics are excellent,
When drilling with an NC drill and conducting conductive on both sides and multiple conductor layers by metal plating by through holes,
Manufacture double-sided wiring boards and wiring boards in order to make metal plating non-uniform because foreign matter and projections such as silicon oxide particles and glass cloth debris are generated in through holes Was difficult.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention improves the state of the inside of a through-hole in a wiring board such as a printed wiring board, thereby preventing problems such as disconnection defects and achieving high reliability. And at the same time, to realize excellent high-frequency characteristics, mechanical strength, workability, and the like.

[0006]

Means for Solving the Problems In order to solve the above problems, the present inventors have conducted intensive studies and as a result have reached the following invention. [1] A wiring board in which a through-hole whose surface is covered with a metal plating film is provided in a substrate having a wiring layer on both surfaces of an insulating base material, and the inner wall surface maximum roughness R of the through-hole is provided.
A wiring board, wherein _max is 50 μm or less. [2] A substrate provided with a wiring layer on both sides of an insulating base material and a conductive layer provided with a circuit pattern or another substrate provided with a wiring layer on both sides of the insulating base material are thermoset to a sheet-like base material. A wiring board laminated with an insulating resin layer impregnated with a conductive resin, wherein a through hole whose surface is covered with a metal plating film is provided in the wiring board, and the inner wall surface of the through hole has a maximum. A wiring board having a roughness R _max of 50 μm or less. [3] The wiring board according to [2], wherein the insulating resin layer contains polybutadiene or polyisoprene. [4] The wiring board according to [2] or [3], wherein the insulating resin layer contains 5 to 60% by volume of silicon oxide particles and 10 to 40% by volume of glass cloth. [5] The wiring board according to any one of [1] to [4], wherein the insulating base material contains polybutadiene or polyisoprene. [6] In a substrate provided with wiring layers on both surfaces of an insulating base material, NC
A method for manufacturing a wiring board including a step of forming a through hole using a drill and then metal plating the through hole, wherein the maximum roughness R _max of the inner wall surface of the through hole after metal plating is set to 50 μm or less. A method for manufacturing a wiring board, comprising: [7] A substrate provided with a wiring layer on both sides of an insulating base material and a conductive layer provided with a circuit pattern or another substrate provided with a wiring layer on both sides of the insulating base material are thermosetted into a sheet-like base material. After laminating and molding through an insulating resin sheet in a B-stage state impregnated with a conductive resin, forming a through hole in the obtained laminate using an NC drill, and metal plating the through hole. A method of manufacturing a plate, wherein the maximum roughness R _max of the inner wall surface of a through hole after metal plating is 50 μm
A method for manufacturing a wiring board, comprising: [8] The method for manufacturing a wiring board according to [7], wherein the insulating resin sheet contains polybutadiene or polyisoprene. [9] The method for manufacturing a wiring board according to any one of [6] to [8], wherein the insulating base material contains polybutadiene or polyisoprene. [10] The method for manufacturing a wiring board according to any one of [6] to [9], wherein the peripheral speed of the NC drill is 150 m / min or less, and the feed speed of the NC drill is 1.0 m / min or less. Method for manufacturing a wiring board. [11] In the method for manufacturing a wiring board according to any one of [6] to [10], when forming a through hole having a diameter of 2 mm or more, the peripheral speed of the NC drill is set to 150 m / min or less,
A method for manufacturing a wiring board, wherein the feed rate of a C drill is 0.2 m / min or less.

In the present invention, since the inner surface roughness R _max of the through hole is set to 50 μm or less, the plating film thickness inside the through hole becomes uniform, and the conduction between the layers becomes good. In the present invention, R _max is more preferably 25 μm or less. In this way, the reliability of conduction between the layers is further improved, and the wiring board can withstand long-term use.

An NC drill used for drilling can be used as long as it is a drill used in the art, but a carbide blade such as WC is preferable in consideration of the degree of wear of the drill. The rotation speed and feed rate of the drill are such that the peripheral speed of the drill is 150 m.
/ Min and a feed rate of 1 m / min or less are preferred. Diameter 2
For drills of mm or more, the peripheral speed is more preferably 150 m / min or less and the feed speed is 0.2 m / min or less. In order to perform drilling with high production efficiency, the number of revolutions and feed rate should be 2m in diameter.
For drills less than m, the peripheral speed is preferably 50 m / min or more and the feed speed is 0.3 m / min or more. For drills with a diameter of 2 mm or more, the peripheral speed is 50 m / min or more and the feed speed is 0.1 m / min.
Minutes or more are preferred. In this way, the maximum roughness R _max of the inner wall surface of the through hole after metal plating can be stably reduced, and R _max can be reduced to 50 μm or less, particularly 25 μm or less.

The inner surface roughness of the through hole can be measured as follows. First, the substrate is cut to expose the inside of the through hole. Next, the inner surface of the through hole is observed with an optical microscope, and the maximum amount of unevenness is measured. This maximum unevenness amount is defined as _Rmax .

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The substrate according to the present invention has a structure in which wiring layers are provided on both surfaces of an insulating base material (hereinafter, appropriately referred to as a "core layer"). As the core layer, for example, a sheet-like base material impregnated with a thermosetting resin is used. This thermosetting resin is not in the B-stage state but in a completely cured state. The core layer can be configured to contain, for example, a thermosetting resin containing silicon oxide particles, glass cloth, polybutadiene or polyisoprene as a main component. Various thermosetting resins can be used, and polybutadiene or a copolymer containing a structural unit derived from butadiene is preferable, and 2,2-polybutadiene is particularly preferable. When such a resin is used, the high-frequency characteristics are significantly improved. In this case, the content of polybutadiene or polyisoprene with respect to the entire thermosetting resin is preferably 50% by mass or more.

As a specific embodiment of the substrate in the present invention, for example, a substrate containing 5 to 60% by volume of silicon oxide particles and 10 to 40% by volume of glass cloth can be mentioned.
As a resin component other than polybutadiene or polyisoprene, for example, a styrene resin can be used as an auxiliary component.

According to the study of the present inventors, it has been confirmed that when a substrate having an insulating base material containing polybutadiene or polyisoprene is used, the metal plating in the through holes tends to be uneven. In this regard, according to the present invention, such a problem is effectively solved, and a wiring board having both good through-hole conduction characteristics and excellent high-frequency characteristics is provided.

The insulating base material constituting the substrate preferably has the following characteristics. That is, 2.4 GHz to 70 G
The dielectric constant in the frequency range of Hz is preferably 3.0
The dielectric loss tangent in the frequency region is preferably 0.0001 or more and 0.01 or less, more preferably 0.0001 or more and 0.007 or less. By using such an insulating base material, the attenuation rate of a high-frequency signal can be reduced and signal transmission can be performed favorably. The relative permittivity and the dielectric loss tangent of the insulating substrate are measured by a cavity resonator method and a traveling wave resonance method.

The insulating resin layer and the insulating resin sheet of the present invention are obtained by impregnating a sheet-shaped base material with a thermosetting resin, and may contain a filler and various additives. A specific example is prepreg. In the present invention, the “insulating resin sheet” refers to a B-stage state, and the state after laminating and forming the same under heating and pressure is referred to as an “insulating resin layer”.

Various thermosetting resins can be used as the insulating resin layer and the insulating resin sheet. Epoxy resins, polybutadienes, copolymers containing structural units derived from butadiene, and the like can be used. it can. When polybutadiene is used, 2,2-polybutadiene is preferred. In addition, a resin composition having low dielectric constant and low dielectric loss tangent using PPE, PPO, and phenolic resin as subcomponents can also be used. When such a resin is used, the high-frequency characteristics are significantly improved. The content of the thermosetting resin in the insulating resin layer and the insulating resin sheet is preferably 30 to 70% by mass.

As a specific embodiment of the insulating resin layer and the insulating resin sheet in the present invention, for example, one containing 5 to 60% by volume of silicon oxide particles and 10 to 40% by volume of glass cloth can be mentioned. In the present invention, the insulating resin layer and the insulating resin sheet may be singular or plural.

In the present invention, the insulating resin layer preferably has the following characteristics. That is, 2.4 GHz to 7
The dielectric constant in the frequency region of 0 GHz is preferably 3.0 or more and 4.5 or less, and the dielectric loss tangent in the frequency region is preferably 0.0001 or more and 0.018 or less. By using such an insulating resin layer, the attenuation rate of a high-frequency signal can be reduced, and signal transmission can be performed favorably. The relative permittivity and the dielectric loss tangent of the insulating resin layer can be measured based on the results measured by the cavity resonator method and the traveling wave resonance method.

In the present invention, the insulating resin layer and the insulating resin sheet used for interlayer bonding include a sheet-like base material as a constituent element, and the insulating base material forming the substrate also includes a sheet-like base material. Can be. Examples of such a sheet-like substrate include glass fiber, paper, and aramid fiber. The filler includes an organic filler and an inorganic filler. Specific examples of the organic filler include a powder epoxy resin (for example, TEPIC), a melamine resin, a benzoguanamine resin, a urea resin, a crosslinked acrylic polymer, and the like. Specific examples of the inorganic filler include magnesium oxide, calcium carbonate, Zirconium silicate, zirconium oxide, calcium silicate, calcium hydroxide, silicon oxide and the like can be mentioned. In addition, as various additives, barium sulfate, silicon sulfide, talc, clay, bentonite, kaolin, glass fiber, carbon fiber,
Mica, filler such as asbestos, thixotropic agent such as Aerosil, phthalocyanine, phthalocyanine green,
Examples include coloring pigments such as phthalocyanine blue, titanium oxide and carbon black, flame retardants, flame retardant aids, defoamers, adhesion promoters, and leveling agents.

In the present invention, it is preferable that the insulating base material constituting the substrate, the insulating resin layer and the insulating resin sheet used for interlayer bonding have a low water absorption. The range of the water absorption is preferably 0.3% or less. In this way, the change in the dielectric constant and the dielectric loss tangent of the composition due to the amount of moisture absorbed can be suppressed, and loss of reproducibility in the transmission characteristics of high-frequency signals can be prevented.

In the method for manufacturing a wiring board according to the present invention,
Conditions for performing laminating under heat and pressure include, for example,
Heating temperature 100 ° C ~ 250 ° C, heating pressure 10kgf /
cm ^Two~ 60kg weight / cm^Two, Heating time from 5 minutes to 300 minutes
And In order to enhance the interlayer adhesion, the following (i)
To (iii). (I) A heating temperature of 100 ° C. to 250 ° C. and a heating pressure of 10
kg weight / cm^Two~ 60kg weight / cm^Two10 minutes heating time
To 180 minutes. (Ii) a heating temperature of 100 ° C to 200 ° C, more preferably
Is 100 ° C to 150 ° C, heating pressure is 10kgf / cm^Two
~ 60kg weight / cm^TwoAnd heating time from 10 minutes to 180 minutes
After performing the first heat treatment under the following conditions, the heating temperature is reduced to 15
0 ° C to 250 ° C, more preferably 160 ° C to 250 ° C
And the heating pressure is 10 kgf / cm^Two~ 60kg weight / c
m^Two, The second heating condition is 10 minutes to 180 minutes.
A heat treatment is performed. The second heat treatment is more than the first heat treatment
It is also preferable to perform the treatment at a high temperature. In addition, the second module
Heat treatment may be longer than the first heat treatment
preferable. (Iii) After the treatment of (ii), the heating temperature is set to 180 ° C.
~ 250 ° C, heating pressure 10kgf / cm^Two~ 60kg
Weight / cm^TwoUnder the condition that the heating time is 10 minutes to 180 minutes.
A third heat treatment is performed.

By adopting the above conditions, the interlayer adhesive strength can be sufficiently increased. In particular, if a multi-step process is performed as in (ii) or (iii), high adhesive strength can be stably exhibited. In addition, by heating in a two-stage system and a three-stage system, it is possible to minimize the displacement between the laminations during thermocompression bonding.

In the method for manufacturing a wiring board of the present invention, a step of performing a blackening treatment is performed before the step of laminating under heat and pressure, and after this step, the step of laminating under the above heat and pressure is performed within 48 hours. It is also possible to adopt a configuration in which a molding step is performed.

If the surface of the wiring layer such as a copper foil is left as it is, it is degraded by heating or moisture absorption, causing delamination or the like. In order to prevent such troubles, a blackening treatment for forming a black oxide film on the surface of the wiring layer using an oxidizing agent is effective. Thereby, the interlayer adhesive strength is improved.

In the present invention, a surface treatment other than the blackening treatment may be performed in order to improve the interlayer adhesion strength.

By the way, when the above-described blackening treatment is performed, the interlayer adhesion strength may vary from product to product depending on the treatment process. In the present invention, if a process of performing lamination molding within 48 hours after the blackening treatment is employed, such a variation in interlayer adhesive strength can be significantly reduced.

The material of the wiring layer and the conductive layer in the present invention is:
It can be used if it is a conductive metal or non-metal,
Copper foil and copper alloy foil are preferable as materials that can be obtained at low cost. Ni, Zn, Cr, M on the surface of copper foil and copper alloy foil
A foil having an antioxidant film formed of o, Co, In or the like is more preferable. For the purpose of preventing oxidation and obtaining a sufficient peel strength, it is also preferable to perform blackening treatment, CZ treatment, NBD treatment, MD treatment and the like.

There is no particular limitation on the method of forming a circuit on the wiring layer. For example, after laminating a dry film (manufactured by Asahi Kasei Corporation) that can be exposed and developed on the wiring layer,
After exposure, curing, and development, a circuit can be formed by etching with an iron chloride solution, a copper chloride solution, or the like.

The number of wiring layers of the wiring board is not limited.
About 30 to 30 layers are preferable. When increasing the number of layers, the number of substrates (core materials) can be increased as appropriate.
If a board and an insulating resin layer are alternately laminated and formed under heat and pressure, a wiring board having a desired number of layers can be obtained.

As a wiring method between the insulating layers, the substrate may be NC
Drilling is performed, and a conductive metal film is formed by electroless plating or electrolytic plating, and wiring can be performed. C
The insulating layer resin may be perforated by an O ₂ laser, an excimer laser, or the like, and a conductive metal film may be formed by electroless plating, electrolytic plating, or the like. Alternatively, a conductive bump may be formed on a conductive sheet, a prepreg may be laminated thereon, and a through-type wiring may be formed by through-bonding and thermo-compression bonding.

After forming the wiring board, the printed wiring board can be manufactured by an ordinary method. In detail, after applying, exposing, curing and developing solder ink (manufactured by Tamura Kaken, Taiyo Ink)
It is preferable to perform electrode formation such as I-Au plating, Ag plating, and flux, and display parts and the like by silk printing.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. In the examples, _Rmax was measured by observing the inner surface of the through hole with an optical microscope.

Example 1 A substrate having a copper foil having a thickness of 18 μm provided on the front and back surfaces of a core layer was prepared. The core layer, with respect to the entire core layer,
It is configured to contain 50% by volume of silicon oxide particles, 25% by volume of glass cloth, and 25% by volume of thermosetting resin. The thermosetting resin is mainly composed of a polybutadiene resin. The thickness of the core layer is about 0.20 mm.

This substrate is cut into a size of 500 × 400 mm, stacked into 10 sheets, sandwiched between a discard plate and a backing plate, and set on an NC drilling machine (Hitachi Via Mechanics, drill: Toshiba Tungaloy). Diameter 2.
Drilling was performed using a 5 mm drill. The drilling conditions were as follows: a drill having a diameter of 0.4 mm was rotated at 100,000 rpm, a peripheral speed was 125 m / min, a feed speed was 0.8 m / min. The rotation speed of the drill having a diameter of 2.5 mm was 18,000 rotations / minute, the peripheral speed was 140 m / minute, and the feed speed was 0.18 m / minute. Next, desmearing, electroless copper plating, and electrolytic copper plating were performed to form through holes. After the formation of the through holes, a part of the through holes having a diameter of 0.4 mm and a diameter of 2.5 mm was cut, and the surface shape was observed with a focus microscope. As a result, the maximum surface roughness (R _max ) in the through hole having a diameter of 0.4 mm was 18 μm, and the maximum roughness was 2.5 mm.
Had an inner surface roughness of 15 μm and a smooth inner wall surface.

Next, buffing and soft etching were performed to laminate a dry film (Sunfort AQ-3058: manufactured by Asahi Kasei). The exposure of the dry film was performed using a film in which a wiring pattern such as a signal line was previously printed on a silver halide film using an exposure machine. Thereafter, an unnecessary dry film was removed by development, an unnecessary copper foil was removed by etching, and then the dry film was removed to prepare a circuit-formed substrate. Thereafter, the solder resist was removed from a predetermined electrode portion by applying a solder resist (manufactured by Tamura Kaken), exposing and developing. After that, Ni-
Au plating was performed to produce an electrode for the component mounting portion.

A good substrate was obtained from the manufactured substrate without peeling. As a reliability evaluation of the substrate, a thermal shock test (repeated test of 260 ° C. for 20 seconds and 25 ° C. for 20 seconds) was performed 400 times, and as a result, the rate of change of the resistance of the signal circuit was 0.1%.
It was less than that, and the substrate sufficiently reflected the conductive connection reliability of the through hole. Further, as a result of performing a soldering heat test in which the formed substrate was boiled and absorbed and then immersed in a solder bath at 288 ° C. for 10 seconds, no peeling and swelling was observed, and the component mounting characteristics were sufficient. By forming a through hole having an inner wall surface roughness (R _max ) of 50 μm or less, a printed wiring board with sufficient inter-layer conductive reliability was obtained.

Example 2 A core material (substrate) having an 18 μm-thick copper foil provided on the front and back surfaces of a core layer was prepared. The core layer is composed of 50% by volume of silicon oxide particles and glass cloth 25 with respect to the entire core layer.
The composition contains 25% by volume and 25% by volume of a thermosetting resin. The thermosetting resin is mainly composed of a polybutadiene resin. The thickness of the core layer is about 0.20 mm.

The substrate was cut into a size of 500 mm × 400 mm, subjected to buffing and soft etching, and laminated with a dry film (Sunfort AQ-3058: manufactured by Asahi Kasei). The exposure of the dry film was performed using a film in which a wiring pattern such as a signal line was previously printed on a silver halide film using an exposure machine. Thereafter, the unnecessary dry film was removed by development, the unnecessary copper foil was removed by etching, and then the dry film was removed to produce a circuit-formed substrate. Next, the surface layer of the copper foil was subjected to a reduction treatment by a blackening reduction treatment.

Subsequently, a B-stage resin (prepreg) having a size of 500 mm × 400 mm and a thickness of 0.1 mm before the thermosetting of the resin composition was prepared, and two prepregs were used inside the two core substrates on which the circuit was formed to laminate. Then, it was heated and pressed by a hot press at 180 ° C. and 30 kg / cm ² for 2 hours.

The obtained substrate was subjected to NC drilling (NC: manufactured by Hitachi Via Mechanics, drill: Toshiba Tungaloy).
Drill 0.5mm, 1mm, 2mm diameter, 20μm thick by desmearing, electroless plating and electrolytic plating
Copper plating was performed. The conditions of the NC drill were as follows. (i) Drilling 0.5 mm diameter 80,000 revolutions / min, peripheral speed 125 m / min (ii) Drilling 1 mm diameter 40,000 revolutions / min, peripheral speed 125 m / min Feeding speed: 0.8 m / min (iii) Diameter Drilling of 2mm 20,000 rotations / min, peripheral speed 125m / min Feeding speed: 0.18m / min The through hole after copper plating was modeled and the cross section was measured with a microscope for inner surface roughness. The degree (R _max ) is 0.5μ in diameter and 18μ in through hole.
m, 1 mm in diameter was 15 μm, and 2 mm in diameter was 12 μm. Then, after buffing and soft etching the copper surface of the base material, dry film (Sunfort AQ)
-3058: manufactured by Asahi Kasei), and then exposed using a silver halide film on which the circuit of the substrate was printed.
Unnecessary dry film was removed by development, copper foil was removed by etching, and cured dry film was removed, and a predetermined circuit was formed. Thereafter, the solder resist was removed from a predetermined electrode portion by applying a solder resist (manufactured by Tamura Kaken), exposing and developing. Then, Ni-Au
Plating was performed to produce an electrode for the component mounting portion. A good substrate without peeling was obtained from the manufactured substrate. A thermal shock test (260 ° C. for 20 seconds and 2
(Repetition test at 5 ° C. for 20 seconds) was performed 400 times. As a result, the substrate had a change rate of the resistance of the signal circuit of less than 0.1% and sufficiently reflected the reliability of the conductive connection of the through hole. Further, as a result of performing a soldering heat test in which the formed substrate was boiled and absorbed and then immersed in a solder bath at 288 ° C. for 10 seconds, no peeling and swelling was observed, and the component mounting characteristics were sufficient. The inner wall surface roughness (R _max ) of the through hole is 50μ
m or less, the characteristics were sufficient to have the reliability of conductive connection between layers.

Examples 3 to 5 The same core material (substrate) as in Example 1 was used. A printed circuit board was manufactured in the same manner as in Example 2 except that the number of core members formed with circuits was changed, the number of prepregs was changed accordingly, and the conditions for drilling NC were changed. Table 1 shows the manufacturing conditions, the conditions of the NC drill, and the measurement results of the surface roughness of the inner wall surface of the through hole. As a reliability evaluation, a thermal shock test and a solder heat resistance test were carried out in the same manner as in Example 1. As a result, the change in electric resistance was less than 0.1%, and the substrate was highly reliable without solder blistering. As a result of obtaining a smooth surface having a surface roughness (R _max ) of 50 μm or less on the inner wall surface of the through hole, the printed circuit board had excellent conduction reliability between layers.

[0041]

[Table 1]

Comparative Example 1 The same core material as in Example 1 was used. Using an NC drilling machine (Hitachi Via Mechanics, drill: Toshiba Tungaloy), drilling of 0.5 mm, 1 mm, and 2 mm diameter was performed. The drill conditions were as follows. (i) Drilling of 0.5 mm diameter Rotation speed of 160,000 rotations / minute Weekly speed of 250 m / min Feeding speed of 1.6 m / min (ii) Drilling of 1 mm diameter Rotation speed of 80,000 rotations / minute Circumferential speed of 250 m / min Feeding Speed: 1.6 m / min (iii) Drilling of 2 mm diameter Rotation speed: 40,000 revolutions / min Circumferential speed: 250 m / min Feeding speed: 0.36 m / min As in Example 1, desmearing and plating are performed to create through holes. did. The substrate is cut at the through hole in the same manner as in Example 1, and the inner wall surface roughness R of the through hole is cut.
As a result of observing the _maximum , it was 75 μm at a diameter of 0.5 mm, 95 μm at a diameter of 1 mm, and 105 μm at a diameter of 2 mm, indicating that the smoothness of the inner wall surface was poor. Next, a circuit was formed in the same manner as in Example 1. As a through hole reliability test,
As in Example 1, a thermal shock test and a solder heat resistance test were performed. As a result of the thermal shock test, the rate of change from the initial resistance value after 400 times was increased by 10%, and the reliability was poor. No abnormalities were found in the solder heat test. Surface roughness of the inner wall surface of the through hole 50μ
m, the printed wiring board had poor conduction reliability between layers.

[0043]

As described above, according to the present invention, the flatness inside the through hole is improved, the plating thickness inside the hole becomes uniform, and the reliability of conduction between the layers of the wiring plate is improved.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ichiro Nakayama 5-32-1, Tomuro, Atsugi-shi, Kanagawa Prefecture Inside Printtech Co., Ltd. (72) Inventor Hiroichi Yabuuchi 580-32 Nagaura Sodegaura-shi, Chiba Mitsui Chemicals (72) Inventor Yoshito Uehara 580-32 Nagaura, Sodegaura-shi, Chiba F-term in Mitsui Chemicals Co., Ltd.

Claims (11)

[Claims] 1. A wiring board provided with a through hole whose surface is covered with a metal plating film in a substrate provided with wiring layers on both surfaces of an insulating base material, wherein the maximum roughness of the inner wall surface of the through hole is provided. A wiring board, wherein R _max is 50 μm or less. 2. A sheet-like base material comprising: a substrate provided with wiring layers on both surfaces of an insulating base material; and a conductive layer provided with a circuit pattern or another substrate provided with wiring layers on both surfaces of the insulating base material. A wiring board laminated via an insulating resin layer impregnated with a thermosetting resin, wherein a through hole whose surface is covered with a metal plating film is provided in the wiring board, and an inner wall of the through hole is provided. A wiring board having a maximum surface roughness R _max of 50 μm or less. 3. The wiring board according to claim 2, wherein the insulating resin layer contains polybutadiene or polyisoprene. 4. The wiring board according to claim 2, wherein the insulating resin layer contains 5 to 60% by volume of silicon oxide particles and 10 to 40% by volume of glass cloth. 5. The wiring board according to claim 1, wherein said insulating base material contains polybutadiene or polyisoprene. 6. A substrate provided with wiring layers on both surfaces of an insulating base material.
After forming a through hole using an NC drill,
Manufacture of wiring boards including the step of metal plating through holes
The method, wherein the inner wall surface of the through hole after metal plating
Maximum roughness R_{ma x}Is not more than 50 μm
Manufacturing method of wiring board. 7. A sheet-like base material comprising: a substrate provided with wiring layers on both sides of an insulating base material; and a conductive layer provided with a circuit pattern or another substrate provided with wiring layers on both sides of the insulating base material. After laminating and molding through an insulating resin sheet in a B-stage state impregnated with a thermosetting resin, a through-hole is formed in the obtained laminate using an NC drill, and the through-hole is metal-plated. A method for manufacturing a wiring board, comprising:
Inner wall surface maximum roughness R _max of through hole after metal plating
Is not more than 50 μm. 8. The method for manufacturing a wiring board according to claim 7, wherein the insulating resin sheet contains polybutadiene or polyisoprene. 9. The method for manufacturing a wiring board according to claim 6, wherein said insulating base material contains polybutadiene or polyisoprene. 10. The method for manufacturing a wiring board according to claim 6, wherein the peripheral speed of the NC drill is set to 150 m.
A method for manufacturing a wiring board, wherein the feed rate of an NC drill is 1.0 m / min or less. 11. The method for manufacturing a wiring board according to claim 6, wherein when forming a through hole having a diameter of 2 mm or more, the peripheral speed of the NC drill is 150 m / min or less, and the feed speed of the NC drill is 0. .2 m / min or less.