JPH08274429A - Wiring board - Google Patents

Abstract

PURPOSE: To provide a wiring board wherein an electronic component such as a semiconductor element, a capacitor and a resistor which are driven at a fast speed can be mounted and connected at a specified position firmly and accurately. CONSTITUTION: This wiring board is formed by applying a wiring conductor 2 to an inside and a surface of an insulation substrate 1 consisting of a glass ceramic sintered body. The wiring conductor 2 is formed of silver powder and gold powder or formed by coating a surface thereof with a gold layer, and a surface part 1a alone of the insulation substrate 1 is colored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board on which electronic parts such as semiconductor elements, capacitors and resistors are mounted.

[0002]

2. Description of the Related Art Conventionally, a wiring board is generally composed of a plurality of wiring conductors made of a refractory metal powder of tungsten, molybdenum, manganese or the like on and inside an insulating base made of an electrically insulating material such as an aluminum oxide sintered body. The upper surface of the insulating base is formed by mounting electronic components such as semiconductor elements, capacitors, and resistors on the upper surface of the insulating base and connecting electrodes of the electronic component to wiring conductors through solder. Each electronic component mounted on the board is electrically connected to each other via a wiring conductor.

However, in this conventional wiring board, since the relative permittivity of the aluminum oxide sintered body constituting the insulating base is as high as 9.5 to 10 (room temperature 1 MHz), an electric signal transmitted through the wiring conductor formed on the insulating base is obtained. The propagation speed is low, so that the semiconductor element that requires high-speed propagation of the electric signal cannot be mounted.

Since the electric resistance values of tungsten, molybdenum, etc. constituting the wiring conductor are high, the voltage drop of the electric signal transmitted through the wiring conductor is large, so that the wiring conductor cannot be made fine and the wiring board cannot be made compact and high-density.

It had drawbacks such as

Therefore, in order to solve the above-mentioned drawbacks, there has been proposed a wiring board in which an insulating substrate is formed of a glass ceramic sintered body and a wiring conductor is formed of a powder of copper, silver, gold or the like.

According to such a wiring board, the relative permittivity of the glass ceramics sintered body constituting the insulating substrate is 5.5 (room temperature 1M
Since it is as low as Hz), the propagation speed of the electric signal transmitted through the wiring conductor formed on the insulating base does not slow down, and it becomes possible to mount a semiconductor element that requires high speed propagation.

Further, according to this wiring board, the firing temperature of the insulating substrate is low, and the wiring conductor can be formed of copper, silver, or gold having a low conduction resistance, so that the voltage drop of the electric signal transmitted through the wiring conductor is small and the wiring is It is also possible to miniaturize the conductor to make the wiring board small and high-density.

In the wiring board, if the wiring conductor is formed of copper powder, the copper powder is a metal that is easily oxidized, so that an oxide film is formed on the exposed outer surface of the wiring conductor in a short time. When an oxide film is formed on the surface of a wiring conductor, the oxide film has poor solder wettability, so that the electrode of an electronic component cannot be firmly connected to the wiring conductor through solder. Nickel and gold, which are excellent in corrosion resistance, are sequentially deposited on the surface of the formed wiring conductor by a plating method.

[0010]

However, since the wiring substrate has an insulating base made of a glass-ceramic sintered body of white color and its light reflectance is close to that of silver or gold. Recognizing the position of the wiring conductor and mounting the electronic component at a predetermined position on the wiring board When mounting an electronic component such as a semiconductor element or capacitor on the wiring board using an automounter, the automounter determines the position of the wiring conductor. It was not possible to accurately recognize it, and as a result, it caused a drawback that it was impossible to accurately mount electronic components at predetermined positions on the wiring board.

In order to solve the above drawbacks, coloring agents such as iron oxide, cobalt oxide, manganese oxide, chromium oxide, and nickel oxide are added to an insulating base made of a glass-ceramic sintered body of a wiring board to make the entire insulating base black. It is conceivable that the light reflectance is different from the light reflectance of silver, gold, etc. forming the wiring conductor by making the light brown or brown.

However, when a coloring agent such as iron oxide or cobalt oxide is added to an insulating substrate made of a glass ceramics sintered body, the coloring agent has a large dielectric loss, so that when an electric signal propagates through the wiring conductor at a high speed, The drawback is that the signal is greatly attenuated.

[0013]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned drawbacks, and an object thereof is to mount and connect electronic components such as a semiconductor element, a capacitor, and a resistor, which are driven at high speed, at a predetermined position accurately and firmly. An object is to provide a wiring board that can be used.

[0014]

SUMMARY OF THE INVENTION The present invention is a wiring board in which a wiring conductor is adhered to the inside and the surface of an insulating substrate made of a glass ceramic sintered body, and the surface of the wiring conductor is covered with a gold layer. In addition, only the surface portion of the insulating substrate is colored.

Further, the present invention is a wiring board formed by coating a wiring conductor on the inside and the surface of an insulating base made of a glass ceramics sintered body, wherein the wiring conductor is formed of silver powder or gold powder and the insulating base is formed. It is characterized in that only the surface portion of is colored.

[0016]

According to the wiring board of the present invention, since the surface portion of the insulating substrate is colored, the wiring conductor is insulated from the wiring conductor even if the wiring conductor is formed of silver or gold or the surface is covered with gold. The light reflectance of the substrate is different, which allows the automounter to accurately recognize the position of the wiring conductor, and it is possible to mount electronic components such as a semiconductor element and a capacitor at a predetermined position on the wiring board extremely accurately.

Further, according to the wiring board of the present invention, since only the surface portion of the insulating substrate is colored, the dielectric loss of the entire insulating substrate does not increase, and as a result, an electric signal is propagated to the wiring conductor at high speed. However, the electric signal is not greatly attenuated.

[0018]

The present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of a wiring board of the present invention, in which 1 is an insulating substrate and 2 is a wiring conductor. The wiring board 2 is formed by attaching the wiring conductor 2 to the insulating substrate 1.

On the upper surface of the insulating substrate 1 of the wiring board A, electronic components such as the semiconductor element 3 and the capacitor 4 are mounted,
It functions as a support member that supports electronic components such as the semiconductor element 3 and the capacitor 4.

The insulating substrate 1 is made of, for example, a glass-ceramics sintered body having 20.0 to 28.0% by weight of alumina and the balance being borosilicate glass. , 26.0 to 3
Borosilicate glass powder consisting of 2.0 wt% alumina, 8.0 to 15.0 wt% magnesium oxide, 5.0 to 10.0 wt% zinc oxide, 20.0 to 28.0 wt% alumina powder and suitable organic binder, organic solvent, plasticizer , A dispersant is added and mixed to form a slurry, and the slurry is formed into a sheet by a conventionally known doctor blade method or calendar roll method to obtain a green sheet (raw sheet), and then the green sheet Appropriate punching is applied to the product and multiple sheets are laminated,
It is manufactured by firing at a temperature of.

The insulating substrate 1 made of the glass ceramics sintered body has a low relative dielectric constant of 5.5 (room temperature 1 MHz) or less,
Therefore, the propagation speed of the electric signal transmitted through the wiring conductor 2 attached to the inside and the surface of the insulating base 1 becomes extremely high, and as a result, the mounting of the semiconductor element 3 requiring the high-speed propagation of the electric signal on the insulating base 1 is not possible. It will be possible.

Further, a plurality of wiring conductors are further provided inside and on the surface of the insulating substrate 1 made of the glass ceramics sintered body.
2 is deposited on the wiring conductor 2 and the insulating substrate 1
The electrodes of the semiconductor element 3 and the capacitor 4 mounted on top are connected via solder, so that the electronic components such as the semiconductor element 3 and the capacitor 4 are electrically connected to each other via the wiring conductor 2. Will be done.

The wiring conductor 2 is made of copper powder, silver powder, gold powder or the like. For example, a copper paste obtained by adding and mixing ethyl cellulose or an acrylic resin and a solvent such as alpha-terpineol to the insulating powder is used as the insulating substrate 1. Insulating substrate 1 is formed by printing and applying a predetermined pattern to the formed green sheet in advance by a conventionally known screen printing method or the like.
A predetermined pattern is deposited and formed on the inside and the surface of the.

When the wiring conductor 2 is formed of copper powder, since copper is a metal that is easily oxidized, the exposed outer surface of the wiring conductor 2 made of copper powder is plated with nickel and gold to prevent oxidation. Layers are sequentially deposited by the method.

Further, since the wiring conductor 2 is formed of gold, silver, copper or the like having a small electric resistance value, the voltage drop of the electric signal transmitted through the wiring conductor 2 becomes extremely small, and as a result, the wiring conductor 2 is By miniaturization, the wiring conductor A can be miniaturized and high density can be achieved.

Further, in the wiring board A composed of the insulating base body 1 made of the glass ceramics sintered body and the wiring conductor 2, only the surface portion 1a of the insulating base body 1 is colored black, brown or dark brown. The light reflectance of the surface portion 1a differs from the light reflectance of the wiring conductor. Therefore, when electronic components such as the semiconductor element 3 and the capacitor 4 are mounted at predetermined positions on the wiring board A by using the automounter, the automounter accurately recognizes the position of the wiring conductor 2 and the semiconductor element 3
Electronic components such as the capacitor 4 and the capacitor 4 can be mounted extremely accurately at a predetermined position on the wiring board A.

Since only the surface portion 1a of the insulating substrate 1 is colored black, brown or dark brown, the dielectric loss of the entire insulating substrate 1 is not so large, and as a result, the electric signal is transmitted to the wiring conductor 2. The electrical signal will not be greatly attenuated even if it is propagated at high speed.

As a method of coloring only the surface portion 1a of the insulating substrate 1 in black, brown or dark brown, when a plurality of green sheets are laminated and fired to obtain the insulating substrate 1, the green sheet located at the uppermost layer is used. It is performed by adding a coloring agent such as iron oxide, cobalt oxide, manganese oxide, chromium oxide, or nickel oxide in advance.

Thus, according to the wiring board A described above, electronic components such as the semiconductor element 3 and the capacitor 4 are mounted on the upper surface of the insulating substrate 1 using an automounter, and the electrodes of the semiconductor element 3 and the capacitor 4 are mounted. When connected to the wiring conductor 2 via solder, the electronic components such as the semiconductor element 3 and the capacitor 4 mounted on the upper surface of the insulating substrate 1 are electrically connected to each other through the wiring conductor 2 and thereby the predetermined components are connected. Will form an electric circuit.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the gist of the present invention. For example, in the above-mentioned embodiments, the upper surface of the insulating substrate 1 can be changed. Although the electronic components such as the semiconductor element 3 and the capacitor 4 are mounted only in the above, the electronic components such as the semiconductor element 3 and the capacitor 4 may be mounted on the upper and lower surfaces of the insulating substrate 1.

In this case, the upper and lower surfaces of the insulating substrate 1 are colored.

[0032]

According to the wiring board of the present invention, since the surface portion of the insulating substrate is colored, the wiring conductor is formed of silver or gold.
Alternatively, even if the surface is coated with gold, the light reflectance of the wiring conductor and the insulating substrate are different, which allows the automounter to accurately recognize the position of the wiring conductor, and electronic components such as semiconductor elements and capacitors. Can be mounted extremely accurately at a predetermined position on the wiring board.

Further, according to the wiring board of the present invention, since only the surface portion of the insulating base is colored, the dielectric loss of the entire insulating base does not increase, and as a result, an electric signal is propagated to the wiring conductor at high speed. However, the electric signal is not greatly attenuated.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a wiring board of the present invention.

[Explanation of symbols]

 1 ... Insulating base 1a ... Surface of insulating base 2 ... Wiring conductor 3 ... ..Semiconductor element 4 .... Capacitor A ... Wiring board

Claims (2)

[Claims] 1. A wiring board comprising a wiring conductor adhered to the inside and the surface of an insulating base body made of a glass ceramics sintered body, wherein the surface of the wiring conductor is covered with a gold layer and the surface portion of the insulating base body is covered. A wiring board characterized in that only the color thereof is colored. 2. A wiring board formed by depositing a wiring conductor on the inside and the surface of an insulating base made of a glass ceramics sintered body, wherein the wiring conductor is made of silver powder or gold powder and the surface of the insulating base is formed. A wiring board characterized in that only a portion is colored.