JPH0482295A - Wiring board using coaxial wire and manufacture thereof - Google Patents

Abstract

PURPOSE:To eliminate a crosstalk noise and to make possible a high-speed signal processing by a method wherein the core wires, which are used as signal conductors, of coaxial wires and the shielding layers of the coaxial wires are efficiently isolated from each other. CONSTITUTION:An adherent insulating layer 3 is formed on the surface of a circuit board 2 having a ground layer 1 and plurality of coaxial wires 4 are provided in a desired form. As the wires 4, wires 4 provided with adhesion layers for wire use, which have a superior adhesion to the layers 3 and are provided on the outermost layers of the wires 4 for an increase in the density of elements and the improvement of the workability of wiring, are used. Then, an insulating layer 11 is provided for fixing the wires 4, a laser beam is irradiated on parts, at which through holes 6 and 8 are respectively formed, to remove organic matters and shielding layers 5 of the wires 4 are exposed. As the wires 4 are used on a wiring board in such a way, no crosstalk noise is generated and a signal can be speeded up by using low-dielectric constant layers for wire insulating layers 9 of the wires 4. Moreover, a fluctuation in a dielectric impedance can be lessened by using the wires 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a wiring board using coaxial wires and a method for manufacturing the same.

(Prior Art) With the development of electronic devices, wiring boards with extremely high wiring density are now required.

Examples of such wiring boards with high wiring density include wiring boards that use wires for necessary wiring patterns (hereinafter referred to as multi-wire wiring boards (manufactured by Hitachi Chemical Co., Ltd., trade name)) and multilayer printed wiring boards.

As disclosed in Japanese Patent Publication No. 45-21434, a multi-wire wiring board has an adhesive resin layer (adhesive insulating layer) formed on an inner substrate on which circuits such as a power supply layer and a ground layer are formed. After that, wires coated with polyimide resin etc. are wired using a numerically controlled wiring machine (the wires are coated with adhesive and simultaneously bonded using ultrasonic waves), the wires are fixed using a press, etc., and the wires are It is manufactured by drilling a through hole across the surface and forming an electroless metal layer inside the hole.

Additionally, multilayer printed wiring boards can be formed by forming the outermost layer of an inner-layer circuit board that has multiple inner-layer circuits by etching away unnecessary parts of copper foil, or by plating copper on the necessary parts. There are two methods for laminating and bonding multiple circuit boards: the bottle lamination method, in which the circuit boards and insulating boards are stacked alternately using positioning pins and laminated by heating and pressurizing; and There is a build-up method in which insulating plates are laminated and integrated, unnecessary parts of the copper foil are removed by etching, and this process is repeated6. By the way, recently, automation of OA, FA, etc. is progressing, and unnecessary radiation from robots, control devices, etc. Accidents due to radio wave interference are increasing, and this interference is becoming a social problem.

In order to reduce this unnecessary radiated radio interference, it is becoming common to shield the wiring boards that emit radio waves.
Furthermore, in high-density wiring boards, the influence between conductors on the same wiring board, that is, crosstalk noise, can no longer be ignored on high-speed circuits on the same wiring board. 6 Multi-wire wiring boards and multilayer printed wiring The same goes for the board, in order to meet the demand for higher density, wire core diameter or signal line width Q is 1 mm, and 2.
．． 3 wires between 54mm or 2 wires between 1.27mm
Wooden wiring is used, but in this case the pinch of the wires and signal lines is less than 0.3 mm, and crosstalk between adjacent wires becomes a problem. As a countermeasure against this problem, it is known to increase the distance between wires or signal lines by setting the core diameter of the wire and the width of the signal line to about 0.04 mm. In addition, as a method for converting a wiring board into a wiring board, it is known from Japanese Patent Publication No. 5E154520 to form a ground pattern and a signal line by building and amplifying them, as shown in FIGS. 8(a) to (h). Furthermore, as shown in JP-A-51-71961, the use of a conductive coating film as a shield and the formation of a conductive shield layer by plating are disclosed in US Patent No. 4.
No. 646.436.

(Problem to be solved by the invention) However, in multi-wire wiring boards, reducing the core diameter of the wires reduces the breaking strength of the wires, so ultrasonic waves are applied to obtain appropriate adhesive strength during wiring. The energy creates a significant problem in that wires have a high probability of breaking at intersections, and high-density wiring requires that the wires be well embedded and secured in an adhesive insulating layer. Therefore, the level difference between the top of the wire and the surface of the adhesive insulating resin layer is less than half the wire diameter.
The method using the above-mentioned conductive coating film or the method of forming a conductive layer by plating does not result in forming a shield layer sufficient to reduce crosstalk between adjacent wires.

Even in multilayer printed wiring boards, when the line width is reduced, scratches in the copper foil, waviness in the wA edge plate, etc. greatly affect pattern formation using ultraviolet rays, making it extremely difficult to form signal lines. In addition, forming ground patterns and signal lines by building up as in conventional technology is a major factor in reducing wiring density on wiring boards that require such high-density wiring patterns, and is also a major factor in reducing the wiring density in manufacturing. It also complicates the process.

The present invention has been made in view of these points, and provides a wiring board that is free from crosstalk noise and suitable for high-speed signal processing, and a method for efficiently manufacturing the wiring board.

(Means for Solving Problem !I) The present invention provides a method of eliminating crosstalk by efficiently separating the core wire, which is a signal line, of a coaxial wire and the shield layer.

As shown in FIG. 1, the present invention comprises a circuit board (2) having a ground layer (1), an adhesive insulating layer (3) provided on the surface of this circuit board, and a desired shape formed on the surface. A conduction hole (6) connecting the fixed coaxial wire (4), the shield layer (5) of the coaxial wire, and the ground layer (1), and a conduction hole (8) connected to the core W (7) of the coaxial wire. It is characterized by having the following.

Arrangement of the present invention! A tentative manufacturing method will be explained using FIGS. 2A to 2E.

As shown in FIG. 2A, first, an adhesive insulating layer 3 is formed on the surface of a circuit board 2 having a ground layer 1, and a plurality of coaxial wires are arranged in a desired shape.

As a substrate for forming the ground layer, a commercially available copper foil laminate can be used.

In addition, copper foil is formed on the surface of polyimide film, which has good laser processability, and metal foil is coated and cured with thermosetting or photocuring resin mixed with organic filler, granular inorganic filler, short fiber inorganic filler, etc. , using resin reinforced with organic cloth such as aramid fiber.
Preferably, a single foil laminate is used.

The adhesive insulating layer is not particularly limited as long as it can adhere the coaxial wire, and a resin composition containing natural rubber/synthetic rubber and epoxy resin as main components can be used.

Commercially available coaxial wires can be used, but
In order to increase the density and improve the wiring workability, it is preferable to use a coaxial wire provided with a wire adhesive layer having excellent adhesive strength with the adhesive insulating layer as the outermost layer as shown in FIG. 3.

Examples of this adhesive layer include polyvinyl butyral/epoxy and nylon/phenol.

Further, the core wire of the coaxial wire does not need to be a single wire, and may be a twisted wire. Furthermore, the material of the core wire #1 is copper, copper alloy, aluminum, with a diameter of about 30 to 80 μm,
Aluminum alloys, piano wires clad with copper, and wires whose surfaces are plated with gold, silver, or tin can be used.

Further, as the wire insulating layer, polyimide, polyamideimide, fluorine, methylpentene resin, etc. can be used.

Next, as shown in FIG. 2B, an insulating layer 11 is provided to secure the coaxial wire. This insulating layer may be formed by press laminating a glass/epoxy prepreg or a glass/polyimide prepreg, or may be formed by coating with an epoxy or polyimide film.

Next, as shown in FIG. 2C, a laser beam is irradiated onto the portion of this substrate where the conductive holes 6 and 8 are to be formed to remove organic matter and expose the shield layer of the coaxial wire. At this time, in order to completely expose the shield layer of the coaxial wire in the portion where the conductive hole 8 is formed, it is preferable to irradiate the laser beam from both sides of the substrate.

As the laser beam, a carbon dioxide gas laser is preferable, which can easily remove the organic insulating layer 11 and the adhesive insulating layer 3, but can hardly remove the metal layer of the shield layer 5. Further, a YAG laser or an excimer laser may be used alone or in combination with a carbon dioxide laser.

Next, as shown in FIG. 2D, a metal plating layer is formed by either electroless metal plating or a combination of electroless metal plating and electrolytic metal plating.

Then, at the same time that the through holes 6 are formed by the tenting method, the coaxial wire metal plating layer in the portion where the through holes 8 are to be formed is removed by etching.

As shown in FIG. 2E, one or more of the above substrates and the inner layer 1
2 are overlapped with prepreg interposed therebetween and integrated by pressure and heating. After drilling and metal plating,
The conductive holes 8 and the surface pattern are formed by a tenting method.

The format of the conductive holes 6, the conductive holes 8, and the surface pattern is not limited to the tenting method, and any method currently used for wiring boards can be used. For example, an additive method may be used.

(Function) The wiring board according to the present invention uses coaxial wires, so crosstalk noise does not occur, and high-speed signals are achieved by using a material with a low dielectric constant for the wire insulating layer of the coaxial wires. be able to. Further, by using a coaxial wire, fluctuations in characteristic impedance are extremely small.

Example The composition of the resin composition used in each example is shown below.

[Composition of composition I]

Palladium chloride Ig was added to 300 g of resin with the following composition.
- Mix the solution dissolved in 50 g of methyl-2-pyrrolidone.

・Ethylene glycol monoethyl cartel acetate
:600g/j!・Epoxy resin: 109g//!・Acrylonitrile butadiene copolymer rubber: 20g71 ・Phenol resin: 60g/j2 ・Acrylonitrile butadiene: 144g/41!・Solicon dioxide: 50g/j! [Composition of Composition ■] Phenoquine resin Phenotote, YP-50 (Tobu Kasei Co., Ltd., trade name): 100 parts by weight Methylated melamine, Melan 523 (Hitachi Chemical Co., Ltd., trade name): 15 parts by weight・Glass short fiber, AC; P-01BZ (Asahi N-Hel Co., Ltd., trade name) = 35 parts by weight ・Metabrominated, serous, aromatic acid: 0.3 parts by weight ・Electrocollective plating catalyst Cat #11 (Hitachi Chemical Co., Ltd.) Co., Ltd., trade name) 2.5 parts by weight Cellosolve acetate: 220 parts by weight [Composition of composition ■] Phenotote YP-50 (Tobu Kasei Co., Ltd., trade name): 70 parts by weight Epicote 828 (Yuka Shell Epoxy Co., Ltd., trade name) = 20 parts by weight DEN438 (Dow Chemical Co., trade name): 10 parts by weight S-LEC BM-2 (Sekisui Chemical Co., Ltd., trade name): 20 parts by weight Melan 523 (Hitachi Kasei Kogyo Co., Ltd., trade name) = 20 parts by weight・2PZ-CNS (Shikoku Kasei Kogyo Co., Ltd., trade name): 2 parts by weight・Crystallite VX-X (Tatsumori Co., Ltd., trade name): 20 parts by weight・Cellosolve acetate (Wako Pure Chemical Industries, Ltd., trade name) = 200 parts by weight Example 1 Double-sided roughened copper foil-clad glass/polyimide laminate MCI, -1
-67 (trade name, Hitachi Chemical Co., Ltd.) A circuit board in which a desired etching resist was formed on the surface, and unnecessary copper foil was etched away from the portion that would become the conductive hole 6.8 to form a ground layer. Create. The composition #jyJI has a thickness of 1
00μm dry film, 150℃・I OK
Laminated on the surface of the circuit board under g/c press conditions for 10 minutes, with a core wire of 0.075 mm and an outer diameter of 0.22 mm.
A coaxial wire with a shield layer thickness of 0.01 mm and a wire insulating layer made of fluorine resin was placed using a numerically controlled wiring machine.
The wires were wired in the desired pattern using the wiring rules.

A 180 μm thick toy film of the composition (1) was applied to the surface of this substrate at 150° C. and 10 kg/c.
After laminating under the press conditions of nf for 10 minutes, it was further laminated under the conditions of 170°C and 30 kg/c for 9 minutes.
They were laminated and integrated by heating under pressure for 0 minutes.

A spot diameter of 20 mm is set on the part of this substrate where the conductive hole 6 is to be formed.
A carbon dioxide laser focused at 0 μm was irradiated with an output of 45 W, and the portion where the conductive hole 8 was to be formed was further irradiated with a carbon dioxide laser with a spot diameter of 1 and 7 mm.

After cleaning this substrate, applying a catalyst, and promoting deposition and deposition, electroless copper plating solution Hid-410 (Hitachi Chemical Co., Ltd., trade name) was applied.
After immersion in water for 10 hours to form a copper plating layer with a thickness of 25 μm, an etching resist was formed only on the portion where the conductive holes 6 were to be formed, and the unnecessary copper plating layer was removed by etching.

This board, an inner layer plate made by the engineered foil method, glass polyimide prepreg CIA67N (Hitachi Chemical Co., Ltd., trade name), and copper foil were layered at 180°C.
After applying pressure and heating for 90 minutes at 30 kg/c to integrate the layers, drill holes with a diameter of 0.8 mm at desired locations on the board, wash, apply a catalyst, promote adhesion, and electroless copper plating. An electroless copper plating layer of approximately 35 μm was formed on the inner wall of the hole and the surface of the copper foil, and etching resist was formed at necessary locations such as pads and component mounting terminals, and unnecessary copper was removed by etching.

Example 2 The above composition (■) was applied to a thickness of 10 μm on both sides roughened M foil with a thickness of 35 μm.
0 μm coating, 120°C-30 minutes, 160°C・3
Heating is performed for 0 minutes. Next, an etching resist is formed on the surface, and the copper foil in the portion that will become the conductive hole 6.8 is etched away to produce a circuit board on which a ground layer is formed.

The composition (1) was made into a dry film with a thickness of 100 μm,
Laminate on the surface of the circuit board under pressing conditions of 150°C, 10 kg/c, and 10 minutes. Then, a 108 m thick epoxy/nylon adhesive layer was applied to the surface of the coaxial wire of Example 1 using a numerically controlled wiring machine to achieve the desired wiring density of 2 wires/2.54 mm and a wire pinch of 0.45 mm. I wired the pattern.

The subsequent steps were performed in the same manner as in Example 3.

Example 3 After impregnating the composition (1) into aramid fibers to a semi-cured state, a double-sided roughened copper foil with a thickness of 35 μm was layered and heated at 160°C.
Using this board, which was integrated under pressure and heat under the conditions of -30 kg/cnf and 60 minutes, an etching resist was formed on the surface, and the copper foil in the area that would become the conductive hole 6.8 was removed by etching to form a ground layer. A circuit board is manufactured.

The subsequent steps were performed in the same manner as in Example 1.

Example 4 The same procedure as in Example 1 was conducted using a coaxial wire having a core wire diameter of 0.06 mm, an outer diameter of 0.18 mm, a shield layer thickness of 0.01 mm, and a wire insulating layer made of polyimide resin.

No crosstalk noise in the wiring board manufactured in this manner was observed under the following measurement conditions.

On the other hand, the crosstalk noise of conventional wiring boards manufactured using wires with the shield layer removed is 4 to 45%.
The great effects of the present invention were confirmed.

〔Measurement condition〕

Conductor spacing: 0.4mm Length of conductors installed in parallel: 30cm Induced pulse voltage
:5v Induction pulse width: 500ns Induction pulse rise time: In5

[Brief explanation of drawings]

FIG. 3 is a cross-sectional view of a coaxial wire according to an embodiment of the present invention. Explanation of symbols 1. Ground layer 28 Circuit board 3. Adhesive insulating layer 4. Coaxial wire 5, shield layer
6. Conduction hole 7, core M 8
．． Conductive hole 9, wire insulation layer 10. Power layer 1, 11', insulation layer 12. Inner layer plate 13, adhesive layer for wire 14° Laser processing part (a) (b) Fig. (d) (e) Fig.

Claims (4)

[Claims] 1. A circuit board (2) having a ground layer (1), an adhesive insulating layer (3) provided on the surface of this circuit board, a coaxial wire (4) fixed to the surface in a desired shape, and a coaxial wire A wiring board characterized by comprising a conduction hole (6) connecting a shield layer (5) and a ground layer (1), and a conduction hole (8) connected to a core wire (7) of a coaxial wire. 2. A method for manufacturing a wiring board, comprising the following steps. A. Fixing a plurality of coaxial wires (4) in a desired shape to an adhesive insulating layer (3) provided on the surface of a circuit board (2) having a ground layer (1). B. Step of providing an insulating layer (11) on the surface on which the coaxial wire (4) is provided. C. A step of irradiating the insulating layer (11) and adhesive insulating layer (3) with a laser to remove the portions where the conductive holes (6) and (8) are to be formed. D. Step of forming conductive holes (6) with metal plating. E. Coaxial wire (4) in the part where the conduction hole (8) is formed
a step of removing the shield layer (5); F. A step of integrating the substrate obtained in the above step with the inner layer plate (12) using an insulating layer (11'). G. After drilling, a process of forming conductive holes (8) with metal plating. 3. The wiring board according to claim 1, characterized in that a coaxial wire having an adhesive layer as the outermost layer is used. 4. 4. The insulating layer (11) and the adhesive insulating layer (3) are made of an organic cross organic filler, a granular inorganic filler, a short fiber inorganic filler, and a thermosetting or photocuring resin. wiring board.