JPS61108192A - Low temperature sintered multilayer ceramic substrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a multilayer ceramic substrate, and particularly to a multilayer ceramic substrate that can be fired at a low temperature and thus can utilize gold or silver palladium as a conductor.

(Prior Art) Conventionally, a multilayer ceramic substrate having a structure in which conductive wiring layers and insulating layers are alternately printed on an alumina substrate has been used as a substrate for high-density packaging.

However, in order to manufacture this board, firing must be repeated for each layer printed, which poses problems in terms of workability and economy, and the flatness of the board surface when the multiple layers are It was also difficult to realize fine patterns, and it was only possible to laminate up to about five layers. Furthermore, in this method, it is difficult to use both the upper and lower surfaces of the substrate as minute and effective external lead-out terminals.

In recent years, there has been a remarkable development in IC, T, and SI to realize the miniaturization and high performance of computers, communication peripheral terminal devices, etc., and the demand for higher-density mounting boards has increased accordingly. ing.

On the other hand, a multilayer ceramic substrate produced by the alumina green sheet lamination method solves the drawbacks of conventional multilayer substrates, and is attracting attention as a substrate for mounting high-density LSIs in recent years.

The multilayer ceramic substrate is manufactured by the alumina green sheet 4''RN method according to the following steps.

First, alumina raw material powder is mixed with an organic binder, a lubricant, and an organic solvent to form a slurry, and then a green sheet is formed on an organic film by a casting method or the like. The green sheet peeled from the organic film is patched to a desired size, various patterns of conductors are printed on it, and through holes are formed in the printed sheet using a drill, bottle, etc.

After embedding a conductor for vertical conduction into the printed conductor sheet with the through holes formed therein, each sheet was layered in 4* layers.
It is thermocompressed, cut into predetermined dimensions, and then fired. Also,
In another method, after forming through-holes in each green sheet, various patterns of conductors are printed, conductors are then embedded in the through-holes, and similar steps are performed to form a substrate. In this alumina green sheet lamination method, since alumina is used as the raw material, the firing temperature is as high as 1,500°C, and the conductor must necessarily be a metal with a high resistivity, such as W or Mo. First, the firing had to be carried out in a reducing atmosphere. In this case, W, M.

It is difficult to miniaturize signal wiring due to the resistance value of metals such as metals, and it is also disadvantageous in terms of equipment because of the reducing atmosphere.

Furthermore, in multilayer ceramic substrates using Mo, W, etc. as conductors, when resistors and capacitors are further integrated on the substrate using a thick film method, the normally used thick film paste has a 'C~900
Since it is baked at 1S, there were problems such as oxidation of conductors such as Mo and W, and the intended purpose could not be achieved.

(Objective of the Invention) The object of the present invention is to eliminate these drawbacks17, facilitate multilayering, enable high-density wiring, have high reliability of wiring connections, allow direct mounting of semiconductor chips, and facilitate mass production. It is an object of the present invention to provide a multilayer ceramic substrate that can be manufactured in a variety of ways and that can reduce costs.

(Structure of the Invention) According to the present invention, the ceramic layer is made of a low-temperature sintered material that can be sintered in a temperature range of 500 to 1051°C, and a conductor layer of gold, silver palladium, silver, copper, or nickel, and the conductor is It has a structure in which the through poles formed in the ceramic layer are also filled to provide vertical conduction between each layer, and are further formed to be electrically connected to the external terminal portions on both the upper and lower surfaces of the substrate. A characteristic low temperature sintered multilayer ceramic substrate is obtained.

(Example 1) The low-temperature sintered materials used in this example were: Aluminum oxide 55.0% by weight Silicon dioxide 292% by weight Lead oxide 7.5% by weight Boron oxide 3.1% by weight % Group ■ oxide 26% by weight Group ■ oxide 05% Group ■ oxide 2.1% by weight Selected from zinc oxide and zinc oxide. The group (I) element oxides are selected from titanium oxide, zirconium oxide, and the group I element oxides are selected from oxidized aluminum, potassium oxide, and potassium oxide.

The inorganic material having the above composition undergoes a softening reaction at a temperature of 750°C or higher, followed by a crystallization reaction at a temperature of 850°C or higher. As a result, the sintering reaction is sufficiently completed at a low temperature of about 900° C., resulting in a dense sintered body with excellent mechanical strength.

On the other hand, the conductor material used in this example was silver palladium. The composition of silver-palladium is 85 wt% silver and 15 wt% palladium, and when a paste with this composition is fired at 900°C, the sheet resistance value is lO ~ 12
mΩ/unit ◇ Below, a process for manufacturing a multilayer ceramic substrate using the above-mentioned low-temperature sintered material and silver-palladium conductor material will be explained.

First, a powder of a low-temperature sintering material for forming a ceramic layer was prepared and wet-pulverized in a ball mill for 48 hours. Powder with controlled particle size is dispersed in a solvent together with an organic binder such as polyvinyl butylene, polyvinyl alcohol, or polyacrylic resin to form a slurry. This mud IJNr is made into a uniform green sheet with a thickness of about 10 μm to 190 μm using a roll coater method or a doctor blade method. This green sheet is 170
The green sheet is punched into a shape of MM x 170wtH, and through holes necessary for vertical conduction are formed in the green sheet using a blanking die.

A conductor paste of silver palladium is printed on the punched green sheets at predetermined positions 1d by screen printing, and at the same time it is embedded into the through holes provided in the green sheets. In this way, a conductor is printed, and the green sheets embedded in the through holes are laminated to form a predetermined circuit and bonded by thermocompression. Thereafter, the outer shape was cut into the required shape and baked in air at a temperature of about 900° C. for 1 hour. During the firing process, the binder was sufficiently removed by holding it in a non-reducing atmosphere at 500° C. for 10 hours.

A schematic cross-sectional view of the low-temperature sintered multilayer ceramic substrate thus obtained is shown in FIG. A conductor layer 2 is formed between each layer of the ceramic layer 1, and a conductor 4 is embedded in the through hole of the ceramic layer for vertical continuity between the layers and electrical connection to the external terminal section 3. There is. In this embodiment, a silver-palladium alloy is formed as the conductor.

(Example 2) In this example, aluminum oxide was used as the ceramic material according to the oxide conversion notation 60. Oi weight % Silicon dioxide 232 weight % Lead oxide 30 weight % Boron oxide 72 weight % Group (1) element oxide 38 weight % Group (2) element oxide 12 weight % Group I element oxide 16 weight 1t96 composition.

On the other hand, silver 70'r@fil 96 is used as a conductor material.
A composition of 30% by weight of palladium was used.

The method for manufacturing the multilayer ceramic substrate was the same as in Example 1, except that the composition of the inorganic material and the sintering temperature were approximately 1050 tl. In the substrate obtained in this way, the sheet resistance value of the conductor was 25 to 30 mΩ/hole, and the bending strength as a mechanical property was 9/d or more at 2500, and was in a dense state without grains. Ta.

Furthermore, in this example, the firing was performed in a neutral nitrogen atmosphere, but the same characteristics as those obtained when firing in air were obtained.

This means copper as a conductor material.

This makes it possible to use metals such as nickel, which have a relatively low melting point and are easily oxidized.

(Example 3) As a ceramic material, when following oxide conversion notation Aluminum oxide 45.0% by weight Silicon dioxide 10.2% by weight Lead oxide 184% by weight Boron oxide 10.2% by weight ■Group element oxide 88% by weight ■Group element oxide 51% by weight Group I element oxide 2.3% by weight The composition is

Gold was used as the conductor material. In the case of this ceramic composition, dense sintering was possible at a firing temperature of about 850°C, and the sheet resistance value of the conductor after firing was extremely low, 3 mΩ/mouth or less.

(Example 4) The composition of the ceramic material is shown below.

Aluminum oxide 400% by weight Silicon dioxide 183% by weight Lead oxide 11.0% by weight Boron oxide 145% by weight ■Group element oxide 100 Weight% ■Group element oxide 21% by weight■Group element oxide 41% by weight Conductor material Copper was used and fired at a temperature of 5 feet in a neutral atmosphere of nitrogen gas. By using copper, it has become possible to reduce the cost of multilayer ceramic substrates.

(Example 5) The ceramic material has the following composition.

Aluminum oxide 50.0% by weight Silicon dioxide 22.1% by weight Lead oxide 82% by weight Boron oxide 137% by weight If group element oxide 10% by weight Group 1V element oxide 23% by weight Group ■ oxide 27 Weight % Nickel metal was used as the conductor material, and a dense sintered body of a multilayer ceramic substrate was obtained at a firing temperature of about 100% in a neutral firing atmosphere.

(Effects of the Invention) In a comparison between the present invention and a conventional alumina green sheet method multilayer ceramic substrate, the firing temperature of the ceramic material was increased from the conventional high temperature of 1,500°C to 800°C to 10°C.
The ability to lower the temperature to 50°C has made it possible to use conductor materials that can be fired in neutral or oxidizing atmospheres, such as gold, silver palladium, silver, copper, and nickel, making high-density wiring possible. . Furthermore, compared to other thick-film multilayer methods, it has become easier to achieve high-density multilayering, has high wiring connection reliability, and has made it possible to provide multilayer ceramic substrates that can be mass-produced and reduce costs.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an example of the present invention. In the figure, 1...ceramic layer, 2...conductor layer, 3...
External terminal section, 4... conductor

Claims (1)

[Claims] The structure of a multilayer ceramic substrate consists of a ceramic layer made of a low-temperature sintered material and a conductor layer of gold, silver palladium, silver, copper, or nickel, and the conductor is formed in the ceramic layer so that the conductor is electrically connected between the multilayers. 1. A low-temperature sintered multilayer ceramic substrate, characterized in that the through-holes are also filled, and further the substrate is formed so as to be electrically connected to external terminal portions on both sides of the substrate.