JP3176258B2 - Multilayer wiring board - Google Patents

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 components such as semiconductor elements, capacitors and resistors are mounted.

[0002]

2. Description of the Related Art Conventionally, a multilayer wiring board, particularly a multilayer wiring board having a low conduction resistance of a wiring conductor, generally has an insulating substrate made of an electrically insulating ceramic sintered body such as an aluminum oxide sintered body. In addition, a plurality of wiring conductors made of a high melting point metal powder such as tungsten, molybdenum, manganese, etc. are arranged in a multilayer, and each wiring conductor is provided from a high melting point metal powder such as tungsten, molybdenum, manganese, etc. provided in an insulating base. A semiconductor device, a capacitor, a resistor, and other electronic components mounted on the upper surface of the insulating base and connecting the electrodes of the electronic components to the wiring conductors via solder. Thus, each electronic component mounted on the upper surface of the insulating base is electrically connected to each other via a wiring conductor.

Incidentally, such a conventional multilayer wiring board is usually manufactured by employing a ceramic lamination technique and a thick film technique such as screen printing, and specifically, manufactured by the following method.

[0004] (1) First, an appropriate organic binder, a plasticizer, and a solvent are added to a raw material powder such as aluminum oxide, silicon oxide, and magnesium oxide to form a slurry, which is mixed with a conventionally known doctor blade method. Multiple ceramic green sheets by using tape forming technology such as or calender roll method
(Ceramic raw sheet) is obtained, and thereafter, through holes are formed at predetermined positions of each ceramic green sheet by a boring method.

(2) Next, a suitable glass frit, an organic binder, a plasticizer and a solvent are added to and mixed with a high melting point metal powder such as tungsten or molybdenum to obtain a metal paste, and the metal paste is screen-printed. In this way, a predetermined pattern is printed and applied on the surface of the ceramic green sheet, and the ceramic green sheet is filled in through holes.

(3) Finally, ceramic green sheets coated and filled with a metal paste on the surface and through-holes are laminated one above the other, and thereafter, they are placed 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 multilayer wiring board, the electrical resistance of tungsten and molybdenum forming the wiring conductor and the through-hole conductor is 4 × 1.
^{0 -6 Ω · cm~8 × 10 -6} Ω · cm and high that, the cross-sectional area in the width direction of the wiring conductors generally 250 × 10 ^-3 mm ² ~7
Since the cross-sectional area of the through-hole conductor is as small as 2 × 10 ⁻³ mm ² to 70 × 10 ⁻³ mm ² , whereas the cross-sectional area of the through-hole conductor is 50 × 10 ⁻³ mm ² , When an electric signal is applied to an electronic component, large Joule heat is generated when electricity flows through the through-hole conductor, which locally heats the insulating base and causes cracks and cracks in the insulating base. As a result, In addition, the wiring conductors attached to the insulating base may be broken or the like, resulting in low reliability of electrical connection of each electronic component mounted on the upper surface of the insulating base.

[0008]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned drawbacks, and has as its object to effectively prevent breakage of wiring conductors and through-hole conductors and to reduce the number of electronic components mounted on an insulating substrate. An object of the present invention is to provide a multilayer wiring board that can make electrical connection reliably.

[0009]

According to the present invention, there is provided a multilayer wiring board in which a plurality of wiring conductors formed by firing a metal paste are arranged in a multilayer on an insulating base made of a ceramic sintered body. A multilayer wiring board comprising the wiring conductors connected via through-hole conductors formed by firing a metal paste, wherein the length of the wiring conductor is L ₁ , the cross-sectional area is S ₁ , and the specific resistance is When σ ₁ , the length of the through-hole conductor is L ₂ , the cross-sectional area is S ₂ , and the through-hole specific resistance is σ ₂ , the ratio of the metal powder in the metal paste forming the through-hole conductor is defined as Either the ratio is higher than the ratio of the metal powder in the metal paste to be formed, or the cross-sectional area S ₂ of the through-hole conductor is 30% or more wider than the cross-sectional area S _{1 of the} wiring conductor, or the through-hole conductor before the length L ₂ of the By less length L ₁ of the wiring conductor, it is characterized in that it has a _{σ 1 · L 1 / S 1} ≧ σ 2 · L 2 / S 2.

[0010]

According to the multilayer wiring board of the present invention, the specific resistance of the material is made smaller than that of the wiring conductor by increasing the ratio of the metal powder in the metal paste forming the through-hole conductor, or By making the cross-sectional area 30% or more wider than the cross-sectional area of the wiring conductor or shortening the length to less than or equal to the length of the wiring conductor, the relationship between the wiring board and the through-hole conductor is reduced to reduce the length of the wiring conductor to L _1. , The cross-sectional area is S ₁ , the specific resistance is σ ₁ , the length of the through-hole conductor is L ₂ ,
When the cross-sectional area is S ₂ and the through-hole resistivity is σ ₂ , σ
_{Since 1} · L ₁ / S ₁ ≧ σ ₂ · L ₂ / S ₂ , even when electricity flows through the through-hole conductor, no large Joule heat is generated in the through-hole conductor. There are no cracks or cracks in the base due to local heating, thereby effectively preventing the wiring conductors attached to the insulating base from breaking or the like, and each electronic component mounted on the upper surface of the insulating base. Can be electrically connected via the wiring conductor and the through-hole conductor.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows an embodiment of a multilayer wiring board according to the present invention.
Is an insulating base, 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, a glass ceramic sintered body, etc. Electronic components 4 such as elements, capacitors, and resistors are mounted.

A plurality of wiring conductors 2 are formed in the inside and on the surface of the insulating base 1 in multiple layers.
Are electrically connected via a through-hole conductor 3 provided in the insulating base 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 base 1 to each other, and also electrically connect the electronic components 4 to an external electric circuit. It functions and is made of tungsten, molybdenum, manganese, or the like.

Each of the wiring conductors 2 and the through-hole conductor 3 is formed by reducing the specific resistance of the through-hole conductor 3 or widening the cross-sectional area and shortening the length of the through-hole conductor 3. The relationship with the through-hole conductor 3 is that the length of the wiring conductor is L ₁ , the cross-sectional area is S ₁ , the specific resistance is σ ₁ , the length of the through-hole conductor is L ₂ , the cross-sectional area is S ₂ ,
When the through-hole resistivity is σ ₂ , σ ₁ · L ₁ / S
₁ ≧ σ ₂ · L ₂ / S _2, and the electric resistance of the through-hole conductor 3 is extremely smaller than the electric resistance of the wiring board 2. Even if it flows, no large Joule heat is generated in the through-hole conductor 3, and as a result, there is no occurrence of cracks or cracks due to local heating in the insulating base 1, and the wiring conductor 2 attached to the insulating base 1 Each of the electronic components 4 mounted on the upper surface of the insulating substrate 1 is effectively prevented from being disconnected or the like.
It is possible to reliably make an electrical connection via the.

The wiring conductor 2 and the through-hole conductor 3 are formed by adding a glass frit to a high melting point metal powder such as tungsten or molybdenum. In order to effectively prevent the generation of Joule heat in the through-hole conductor 3 by making it smaller, for example, the amount of glass frit added and contained in the through-hole conductor 3 is made smaller than the amount added and contained in the wiring conductor 2. The proportion of the high melting point metal powder such as tungsten or tungsten may be increased.

If the cross-sectional area of the through-hole conductor 3 is 30% or more wider than the cross-sectional area of the wiring conductor 2, the electric resistance of the through-hole conductor 3 is small, and the joule in the through-hole conductor 3 is reduced. The generation of heat is effectively prevented. Therefore, it is preferable that the cross-sectional area of the through-hole conductor 3 be 30% or more wider than the cross-sectional area of the wiring conductor 2.

Furthermore, if the length of the through-hole conductor 3 is made shorter than 100% of the total length of the wiring conductor 2, the electric resistance of the through-hole conductor 3 becomes small, and the Joule heat generated in the through-hole conductor 3 is reduced. Is effectively prevented. Therefore, it is preferable that the length of the through-hole conductor 3 is shorter than the total length of the wiring conductor 2 by 100% or less.

Further, the insulating substrate 1 of the wiring conductor 2
The one formed on the upper surface of the substrate is further provided with a metal having excellent corrosion resistance, such as nickel and gold, and a good conductive metal to a thickness of 1.0 μm to 20.0 μm by a plating method. 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, the wiring conductor 2 formed on the upper surface of the insulating substrate 1 is further coated on the exposed surface with a highly conductive metal such as nickel or gold having a good corrosion resistance of 1.0 μm to 20 μm by plating. Preferably, it is applied to a thickness of 0 μm.

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

Next, in the above-mentioned multilayer wiring board, by making the specific resistance of the through-hole conductor 3 smaller than the specific resistance of the wiring conductor 2, the generation of Joule heat in the through-hole conductor 3 is effectively prevented. A method for manufacturing a multilayer wiring board will be described with reference to FIGS.

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, 10b
, 10c is, for example, when the insulating substrate of the multilayer wiring board is formed of an aluminum oxide-based sintered body, an organic binder, a plasticizer, and the like suitable for a raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide; A solvent is added and mixed to form a slurry, and thereafter, the slurry is formed into a sheet by employing a conventionally known doctor blade method, calender roll method or the like.

The ceramic green sheets 10a,
The through holes a are formed in the ceramic green sheets 10a and 10b at predetermined positions of the ceramic green sheets 10a and 10b by forming through holes of a predetermined diameter in the ceramic green sheets 10a and 10b by a conventionally known press drilling method.

Next, as shown in FIG. 2 (b), 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 is formed, and at the same time, a metal paste is filled in the through-hole a to form the conductor layer 21 for the through-hole.

The metal paste for forming the wiring conductor pattern 20 is formed by adding a suitable glass frit, an organic binder, a plasticizer, and a solvent to a high melting point metal powder such as tungsten or molybdenum and mixing the mixture to form a paste. the metal paste to form a through-hole conductor layer 21 is made of a metal paste substantially the same composition that form the wiring conductor pattern 20, minus the amount of the glass frit is used. In this case, the addition and mixing amount of the glass frit of the metal paste forming the conductor layer 21 for the through hole is smaller than that of the metal paste forming the wiring conductor pattern 20, and the ratio of the high melting point metal powder such as tungsten is increased. Conductor layer for through hole 21 described later
The specific resistance of the through-hole conductor 3 formed by sintering can be made smaller than the specific resistance of the wiring conductor 2.

The wiring conductor pattern 20 is formed by applying a predetermined metal paste to the ceramic green sheets 10a, 10b, 10c.
Are coated in a predetermined pattern by a screen printing method on each surface of the ceramic green sheets 10a and 10b. This is done by filling.

Next, each of the ceramic green sheets 10a, 10b, 10c in which a wiring conductor pattern 20 is formed on the surface and a through-hole a is filled with a through-hole conductor layer 21 is formed.
As shown in FIG. 2 (c), each ceramic green sheet
10a, 10b, 10c Wiring conductor pattern 20 formed on the surface
Are laminated vertically so that they are electrically connected by the through-hole conductor layer 21 filled in the through-holes a of the ceramic green sheets 10a and 10b.

Finally, the laminated body L is fired in a reducing atmosphere at a temperature of about 1600 ° C., and the ceramic green sheets 10 a, 10 b, 10 c, 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 in which the wiring conductors 2 electrically connected by the through-hole conductors 3 are provided inside and on the surface of the insulating base 1 shown in FIG. 1 is completed. I do.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. The electrical resistance value of the through-hole conductor 3 is reduced by making the specific resistance of the through-hole conductor 3 smaller than the specific resistance of the wiring conductor 2, and the generation of Joule heat in the through-hole conductor 3 is effectively prevented. Increasing the diameter of the through-hole a provided in 10a, 10b to increase the cross-sectional area of the through-hole conductor 3 or reducing the thickness of the ceramic green sheets 10a, 10b and shortening the length of the through-hole conductor 3 As a result, the electric resistance of the through-hole conductor 3 is made smaller than the electric resistance of the wiring conductor 2, thereby effectively preventing the generation of Joule heat in the through-hole conductor 3. May be.

[0031]

According to the multilayer wiring board of the present invention, the specific resistance of the material is made smaller than that of the wiring conductor by increasing the ratio of the metal powder in the metal paste forming the through-hole conductor, or The relation between the wiring board and the through-hole conductor is reduced by making the cross-sectional area of the conductor 30% or more wider than the cross-sectional area of the wiring conductor or shortening the length to not more than the length of the wiring conductor. L ₁ ,
When the cross-sectional area is S ₁ , the specific resistance is σ ₁ , the length of the through-hole conductor is L ₂ , the cross-sectional area is S ₂ , and the through-hole specific resistance is σ ₂ , σ ₁ · L ₁ / S ₁ ≧ σ ₂ - from the fact that without the L ₂ / S _2,
Even when electricity flows through the through-hole conductor, no large Joule heat is generated in the through-hole conductor, and as a result, there is no occurrence of cracks or cracks due to local heating on the insulating base, and thus the insulating base is attached to the insulating base. It is possible to effectively prevent disconnection or the like from occurring in the wiring conductor, and to electrically connect the electronic components mounted on the upper surface of the insulating base via the wiring conductor and the through-hole conductor.

[Brief description of the drawings]

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

2 (a) to 2 (c) are cross-sectional views for explaining respective steps of a method for manufacturing the multilayer wiring board shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulating base 2 ... Wiring conductor 3 ... Through-hole conductor 4 ... Electronic components

Claims (1)

(57) [Claims] To 1. A dielectric in substrate made of a ceramic sintered body, a metal paste the respective wire conductors with arranging a plurality of wiring conductors formed by firing a metal paste on a multilayer
A multilayer wiring board formed by sintering through a through-hole conductor, wherein the length of the wiring conductor is L ₁ , the cross-sectional area is S ₁ , the specific resistance is σ ₁ , the through-hole conductor of length L _2, the sectional area S _2, when the through-hole resistivity was sigma _2, metal paste for forming the through-hole conductor
The ratio of the metal powder in the metal powder to the metal
Higher than the ratio of metal powder in the
The cross-sectional area S ₂ of the through-hole conductor is determined by the cross-sectional area of the wiring conductor.
Or a wider 30% or more than S _1, or the scan
The length L ₂ of the through hole conductor is equal to or less than the length L _{1 of the} wiring conductor.
And by a _{σ 1 · L 1 / S 1} ≧ σ 2 · L 2 / S 2
Multi-layer wiring board, characterized in that the.