JPH08316638A - Multilayer wiring board - Google Patents

Abstract

PURPOSE: To provide a multilayer wiring board which can effectively prevent wiring conductors or through-hole conductors from occurring circuit brake and ensure electronic connection of each electronic part mounted on an insulating body. CONSTITUTION: A multilayer wiring board is comprised of wiring conductive bodies 2 which are arranged in multilayer in an insulating unit 1 made of ceramic sintered body, and wiring conductors 2 connected by through-hole conductors 3. The wiring conductors 2 and the through-hole conductors 3 are made of only one of tungsten, molybdenum or manganese and the cross section of the through-hole conductors 3 are over 30% of the cross section of the wiring conductors 2 in lateral direction.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a multi-layer wiring board, particularly a multi-layer wiring board in which the conduction resistance of a wiring conductor is low, is generally an insulating base made of an electrically insulating ceramic sintered body such as an aluminum oxide sintered body. And a plurality of wiring conductors made of refractory metal powder such as tungsten, molybdenum, manganese, etc. on the surface are provided in multiple layers and each wiring conductor is provided in an insulating substrate. It has a structure in which it is connected by a through-hole conductor, and electronic components such as semiconductor elements, capacitors, and resistors are mounted on the upper surface of an insulating substrate, and the electrodes of the electronic component are connected to wiring conductors via solder. As a result, the electronic components mounted on the upper surface of the insulating substrate are electrically connected to each other via the wiring conductors.

Incidentally, such a conventional multilayer wiring board is usually manufactured by adopting a ceramics stacking technique and a thick film technique such as screen printing. Specifically, it is manufactured by the following method.

That is, (1) First, an appropriate organic binder, a plasticizer, and a solvent are added to and mixed with a raw material powder of aluminum oxide, silicon oxide, magnesium oxide or the like to form a sludge, and this is formed by a conventionally known doctor blade method. A plurality of ceramic green sheets (ceramic green sheets) are obtained by using a tape forming technique such as a calender roll method or the like, and then through holes are formed at predetermined positions of each ceramic green sheet by a drilling method.

(2) Next, a suitable organic binder, a plasticizer, and a solvent are added to and mixed with a refractory metal powder such as tungsten and molybdenum to obtain a metal paste, and the metal paste is screen-printed to obtain the metal paste. The surface of each ceramic green sheet is printed and applied in a predetermined pattern, and the through holes of each ceramic green sheet are filled.

(3) Finally, ceramic green sheets whose surfaces and through holes are coated and filled with a metal paste are laminated one on top of the other, and thereafter, in a reducing atmosphere or a neutral atmosphere, at a temperature of about 1600 ° C. By firing, a multilayer wiring board as a product is completed.

[0007]

However, in this conventional wiring board, the electric resistance value of tungsten and molybdenum forming the wiring conductor and the through-hole conductor is 4 × 10 ^−6.
Ω · cm to 8 × 10 ⁻⁶ Ω · cm, and the cross-sectional area of the wiring conductor in the width direction is generally 250 × 10 ⁻³ mm ^{2 to} 750.
× 10 to ^-3 of a mm ^2, each via a wiring conductor and the through-hole conductors from such that the cross-sectional area of the through-hole conductors is small and ^{2 × 10 -3 mm 2 ~70 ×} 10 -3 mm 2 electrons When an electric signal is applied to a component, a large amount of Joule heat is generated when electricity flows through the through-hole conductor, which locally heats the insulating base material and causes cracks or breaks in the insulating base material. The wiring conductor attached to the insulating substrate has a drawback that the wiring conductor is broken and the electrical connection of each electronic component mounted on the upper surface of the insulating substrate becomes unreliable.

[0008]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned drawbacks, and its purpose is to effectively prevent disconnection from occurring in a wiring conductor or a through-hole conductor, and to prevent the electronic components mounted on an insulating substrate from being broken. It is an object of the present invention to provide a multilayer wiring board capable of ensuring electrical connection.

[0009]

According to the present invention, a plurality of wiring conductors are arranged in multiple layers in an insulating substrate made of a ceramic sintered body, and the respective wiring conductors are connected through through-hole conductors. In the multilayer wiring board, the wiring conductor and the through-hole conductor are formed of at least one of tungsten, molybdenum, and manganese, and the cross-sectional area of the through-hole conductor is 30 with respect to the cross-sectional area in the width direction of the wiring conductor.
% Or more.

[0010]

According to the multilayer wiring board of the present invention, the cross-sectional area of the through-hole conductor connecting each wiring conductor is set to 30% or more of the cross-sectional area of each wiring conductor in the width direction. Does not generate a large amount of Joule heat in the through-hole conductor, and as a result, there is no occurrence of cracks or breaks in the insulating base due to local heating, and thus the wiring conductor attached to the insulating base is prevented. It is possible to effectively prevent the disconnection and the like, and it is possible to reliably electrically connect the electronic components mounted on the upper surface of the insulating substrate through the wiring conductor and the through-hole conductor.

[0011]

The present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of the multilayer wiring board of the present invention.
Is an insulating substrate, 2 is a wiring conductor, and 3 is a through-hole conductor.

The insulating substrate 1 is formed of a ceramic sintered body such as an aluminum oxide sintered body, a mullite sintered body, an aluminum nitride sintered body or a glass ceramic sintered body, and a semiconductor is formed on the upper surface thereof. Electronic components 4 such as elements, capacitors, and resistors are mounted.

The insulating substrate 1 has a plurality of wiring conductors 2 formed in multiple layers inside and on the surface thereof.
Are electrically connected via a through-hole conductor 3 provided in the insulating substrate 1.

The wiring conductor 2 and the through-hole conductor 3 electrically connect the electronic components 4 mounted on the upper surface of the insulating substrate 1 to each other and also electrically connect the electronic components 4 to an external electric circuit. It acts and is formed of at least one of tungsten, molybdenum, and manganese.

The cross-sectional area of the through-hole conductor 3 for electrically connecting the wiring conductors 2 is 30% or more of the cross-sectional area of each wiring conductor 2 in the width direction. Since the area is large, even if electricity flows through the through-hole conductor 3, a large amount of Joule heat is not generated, and as a result, there is no occurrence of cracks or fractures due to local heating in the insulating base body 1. It is effectively prevented that the attached wiring conductor 2 is broken, and each electronic component 4 mounted on the upper surface of the insulating substrate 1 is prevented.
Can be surely electrically connected via the wiring conductor 2 and the through-hole conductor 3.

When the cross-sectional area of the through-hole conductor 3 is less than 30% of the cross-sectional area of each wiring conductor 2 in the width direction, the cross-sectional area of the through-hole conductor 3 becomes narrow, and a large amount of Joule heat is generated when electricity flows. And the insulating substrate 1 is cracked or broken. Therefore, the cross-sectional area of the through-hole conductor 3 is specified to be 30% or more of the cross-sectional area of each wiring conductor 2 in the width direction.

Of the wiring conductors 2 formed on the upper surface of the insulating substrate 1, the exposed surface thereof is further plated with a metal having excellent corrosion resistance such as nickel and gold and having a good conductivity by plating. If it is applied to a thickness of 20.0 μm,
Oxidation corrosion of the wiring conductor 2 is effectively prevented, and the electrical connection between the wiring conductor 2 and the electronic component 4 is improved. Therefore, of the wiring conductors 2 formed on the upper surface of the insulating substrate 1, the exposed surface thereof is coated with a metal having excellent corrosion resistance such as nickel or gold and having a good conductivity by 1.0 to 20. It is preferable to deposit it to a thickness of 0 μm.

Thus, according to the above-mentioned multilayer wiring board, electronic components 4 such as semiconductor elements, capacitors, and resistors are mounted on the upper surface of the insulating substrate 1, and electrodes and terminals of each electronic component 4 are wired via solder or the like. Insulating substrate 1 if connected to 2
The electronic components 4 such as semiconductor elements and capacitors mounted on the upper surface of each are electrically connected to each other via the wiring conductors 2 and the through-hole conductors 3, thereby forming a predetermined electric circuit.

Next, a method of manufacturing the above-mentioned multilayer wiring board will be described with reference to FIGS. 2 (a) to 2 (c).

First, as shown in FIG. 2A, three ceramic green sheets 10a, 10b and 10c are prepared and through holes a are formed at predetermined positions of the ceramic green sheets 10a and 10b.

The ceramic green sheets 10a and 10b
, 10c is, for example, when the insulating substrate of the multilayer wiring board is formed of an aluminum oxide sintered body, an organic binder, a plasticizer, or a suitable organic binder for the raw material powder of aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, etc. It is formed by adding a solvent and mixing it to form a sludge, and then forming the sludge into a sheet by using a conventionally known doctor blade method, calender roll method or the like.

Further, the ceramic green sheet 10a,
The through holes a are formed in the ceramic green sheets 10a, 10b by forming through holes having a predetermined diameter in the ceramic green sheets 10a, 10b by a conventionally known press punching method.

Next, as shown in FIG. 2B, a metal paste is applied in a predetermined pattern on the surface of each of the ceramic green sheets 10a, 10b, 10c to form a wiring conductor pattern 20, and at the same time, through holes are formed. The conductor layer 21 for through holes is formed by filling the inside of a with a metal paste.

The metal paste for forming the wiring conductor pattern 20 and the through-hole conductor layer 21 is obtained by adding a suitable organic binder, a plasticizer and a solvent to a refractory metal powder made of at least one of tungsten, molybdenum and manganese and mixing them. It is formed by forming a paste.

The wiring conductor pattern 20 and the through-hole conductor layer 21 are formed by printing and applying a metal paste on the surface of each of the ceramic green sheets 10a, 10b and 10c by a screen printing method.

Next, each of the ceramic green sheets 10a, 10b, 10c, in which the wiring conductor pattern 20 is formed on the surface and the through-hole conductor layer 21 is filled in the through-hole a.
As shown in Fig. 2 (c), each ceramic green sheet
Wiring conductor pattern 20 formed on the surface of 10a, 10b, 10c
Are laminated vertically so as to be electrically connected by the through-hole conductor layer 21 filled in the through-holes a of the ceramic green sheets 10a and 10b to form a laminated body L.

Finally, the laminated body L is fired in a reducing atmosphere at a temperature of about 1600 ° C., and the ceramic green sheets 10a, 10b, 10c, the wiring conductor pattern 20, and the through-hole conductor filled in the through-hole a. By sintering and integrating the layer 21, a multilayer wiring board as a product having wiring conductors 2 electrically connected by through-hole conductors 3 inside and on the surface of the insulating substrate 1 shown in FIG. 1 is completed. To do.

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.

[0029]

According to the multilayer wiring board of the present invention, the cross-sectional area of the through-hole conductor connecting the wiring conductors is set to 30% or more of the cross-sectional area in the width direction of each wiring conductor. No large Joule heat is generated in the through-hole conductor even when electricity is applied to the through-hole conductor, and as a result, there is no occurrence of cracks or cracks in the insulating base due to local heating, and the wiring attached to the insulating base is thereby prevented. It is possible to effectively prevent the conductor from being broken, and it is possible to reliably electrically connect the electronic components mounted on the upper surface of the insulating substrate via the wiring conductor and the through-hole conductor.

[Brief description of drawings]

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

2A to 2C are cross-sectional views in each step for explaining a method of manufacturing the multilayer wiring board shown in FIG.

[Explanation of symbols]

 1 ... Insulating substrate 2 ... Wiring conductor 3 ... Through-hole conductor 4 ..... electronic components

Claims (1)

[Claims] 1. A multi-layer wiring board comprising a plurality of wiring conductors arranged in multiple layers in an insulating substrate made of a ceramic sintered body, and the wiring conductors being connected via through-hole conductors. A multilayer structure in which the wiring conductor and the through-hole conductor are formed of at least one of tungsten, molybdenum, and manganese, and the cross-sectional area of the through-hole conductor is 30% or more of the cross-sectional area in the width direction of the wiring conductor. Wiring board.