JPH05218652A - Manufacture of ceramic multilayer wiring board - Google Patents

Abstract

PURPOSE:To shorten unbindering process by unbinding a multilayer structure, wherein objects in each of which copper paste is printed on a glass ceramic green sheet and in a through hole and a wiring pattern is made are stacked, in steam atmosphere in high concentration. CONSTITUTION:In the manufacture of a multilayer wiring board capable of increasing signal transmission speed, wherein copper being a low melting point metal, as a conductor material, and glass ceramic lower in dielectric constant are baked at the same time, first a through hole is made in the green sheet for a glass ceramic wiring board, and copper paste is printed in this green sheet and on the green sheet so as to stick a conductor wiring pattern. Next, the multilayer structure being made by stacking these glass ceramic green sheets, whereon wiring patterns are made, into a multilayer is heated in nitrogen atmosphere at high steam pressure to decompose and remove the binder contained in the green sheet and the copper paste. Then, the low resistance of the wiring is maintained by baking it in reductive atmosphere.

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 an LSI element is mounted, and in particular, a low melting point metal, copper, is used as a conductor material, and this and a glass ceramic having a low dielectric constant are simultaneously fired. The present invention relates to a method for manufacturing a multi-layer wiring board that can increase speed. More specifically, it relates to a method for manufacturing a high-density package using the above-mentioned glass ceramic and copper as conductor materials.

[0002]

2. Description of the Related Art Since a multi-layer wiring board can achieve high packaging density, it has been widely used in the field of microelectronics as a high-density package substrate for mounting semiconductor integrated circuit elements and other elements.

As a conductor material used for forming a conductor circuit of a ceramic multilayer substrate of this type, a refractory metal such as molybdenum or tungsten, or gold, has been used so far.
Although noble metals such as silver and palladium are used, the former has a high electric resistance, and the latter has a drawback such as high price or migration, so the electric resistance is lower than these and the price is lower. Cheap copper is the best conductor material.

In the manufacture of a ceramic multilayer wiring board using copper, the firing process for decomposing and removing the binder and sintering the copper wiring and the ceramic component has conventionally been carried out in a neutral atmosphere. The reason why firing is carried out in a neutral atmosphere is that copper is oxidized in the air, the electric resistance is extremely increased, and it is no longer useful as a conductor.

[0005]

According to this method, the binder contained in the substrate material and the conductor material is removed in a neutral atmosphere. However, since the binder decomposition reaction is extremely slow in a neutral atmosphere, this is removed. It takes a very long time to do so, and it is difficult to completely remove the binder, so that it may remain in the substrate as a carbonaceous residue or cause generation of pores. Particularly, in a large-sized multilayer wiring board having a large number of laminated layers, it takes a long time of 100 to 300 hours to remove the binder, and a large amount of nitrogen gas is required. Therefore, it has disadvantages that productivity is low and production cost is high.

Therefore, the present invention aims to solve the above-mentioned conventional problems.

[0007]

Means for Solving the Problems That is, in order to achieve the above-mentioned object, the gist of the means adopted in the present invention is that a glass ceramic green sheet and a green ceramic sheet using a conductor paste containing metal copper powder as a main component are used. The green sheet and the binder contained in the conductor paste are decomposed and removed by heating in a high-concentration water vapor atmosphere by stacking the printed wiring patterns and wiring patterns to form an unsintered multilayer structure. And then firing in a reducing atmosphere.

[0008]

According to the present invention, since metallic copper is mainly used as the raw material of the conductor material, a ceramic multilayer wiring board having a low wiring resistance can be obtained. Moreover, since the binder is removed in a nitrogen atmosphere containing a high concentration of water vapor, the carbonaceous polymer remaining in the thermal decomposition process of the binder is directly combined with the water vapor at high temperature and scatters. The binder is decomposed and removed in a time (10 to 30 hours). In this atmosphere, the equilibrium oxygen partial pressure is 100.
Because of the low oxygen partial pressure of ppm or less, it is possible to minimize the oxidation of the conductive material containing metallic copper as the main component. Finally, by firing in a reducing atmosphere, the slightly oxidized conductor material forming the wiring pattern is reduced and the low resistance of the wiring is maintained.

The nitrogen atmosphere containing high-concentration water vapor is a water vapor partial pressure sufficient to remove the binder and also minimizes the oxidation of metallic copper. The steam partial pressure is preferably in the range of 0.1 to 0.5 atm. When the partial pressure of water vapor is less than 0.1 atm, it is often insufficient to decompose and remove the binder in a short time, and carbon remains in the substrate or pores are generated in the substrate after firing. On the other hand, when the pressure exceeds 0.5 atm, the oxidation of metallic copper cannot be minimized, and the volume increase due to the oxidation of metallic copper easily causes defects such as cracks in the substrate.

[0010]

EXAMPLE Next, a specific example 1 of the present invention will be described in detail.

The composition of the glass is SiO ₂ : 76.6 wt.
%, B ₂ O ₃ : 20.3 wt%, K ₂ O: 2.9 wt%,
A butyl methacrylate resin was mixed with a ceramic powder in which a composition consisting of Al ₂ O ₃ : 0.2% and alumina powder were mixed at a weight ratio of 75/25 and trichloroethylene, tetrachloroethylene and n-butanol 60:17: An organic binder dissolved in a solvent of No. 23 and a plasticizer made of diwabutyl phthalate were added and mixed with a ball mill to prepare a ceramic slurry. Next, after defoaming this slurry with a vacuum defoaming machine, a green sheet having a thickness of 200 to 250 μm was produced from the ceramic slurry by the doctor blade method. Next, after cutting this green sheet into a predetermined size, a diameter of 100 to 150 is obtained at a necessary position.
A μm via hole was formed.

Next, glass powder is added to copper powder and mixed, and an organic vehicle in which ethyl cellulose is dissolved in a mixed solvent of terpineol and n-butyl carbitol acetate is added to this mixed powder to prepare a copper paste, which is screened. The green sheet was printed by a printing method. Further, in this printing step, copper paste was also filled inside the via holes.

After that, a desired number of green sheets printed with the wiring patterns as described above are laminated, and the green sheets are dried at 100 ° C.
Thermocompression bonding was performed at a pressure of 50 kg / cm ² .

Next, in a nitrogen atmosphere in which the partial pressure of water vapor is adjusted to 0.3 atm, the temperature is raised from room temperature to 600 ° C. at a temperature gradient of 1.5 ° C./min, and the temperature is kept at 600 ° C. for 20 hours. After the holding, the temperature was returned to room temperature for binder removal treatment. Next, the temperature was raised from room temperature to 400 ° C. at a temperature gradient of 10 ° C./min in a reducing atmosphere in which 90% of nitrogen gas and 10% of hydrogen gas were mixed, and the temperature was maintained at 400 ° C.
After holding for a time, the atmosphere was replaced with a nitrogen atmosphere. Then 1.
The temperature was raised to 950 ° C. with a temperature gradient of 5 ° C./min, and the temperature was kept at 950 ° C. for 2 hours, then 10 ° C./min
The mixture was cooled from 950 ° C. to room temperature with a temperature gradient of and baked.

When the resistance value of the wiring inside the ceramic multi-layer substrate manufactured by the above steps was measured,
It was 0.2 Ω / cm. In addition, as a result of visual observation, generation of cracks and the like was not recognized, generation of residual voids often occurred when the binder was insufficiently removed, and residual carbon was 200 ppm or less. The results are shown in Table 1. A ceramic multilayer wiring board was manufactured in the same manner as in Example 1, except that the water vapor partial pressure and the removal time at the time of removing the binder were changed as shown in Table 1. As a result, the internal wiring resistance as shown in Table 1 was obtained. Further, the results shown in Table 1 were obtained for the occurrence of cracks and residual carbon.

When the partial pressure of water vapor was 0.1 atm or less, the residual carbon exceeded 300 ppm, and at 0.5 atm or more, the oxidation of copper proceeded, and the volume expanded and cracks occurred.

[0017]

[Table 1]

[0018]

As described above, according to the method for manufacturing a ceramic multilayer wiring board of the present invention, the binder removal process is performed in a nitrogen atmosphere containing a high concentration of water vapor, so that the binder removal process can be shortened. High productivity and no reduction in mechanical strength or electrical characteristics caused by insufficient binder removal. In addition, there is no occurrence of cracks or the like caused by the oxidation of the conductor. Further, since metal copper is used as the conductor, the wiring resistance of the conductor is low, and the signal propagation speed can be increased.

Claims (3)

[Claims] 1. A step of forming a through hole in a green sheet for a glass-ceramic wiring board, printing a copper paste in the through hole and on the sheet to attach a conductor wiring pattern, and a glass on which the wiring pattern is formed. A step of laminating the ceramic green sheets, and heating the multilayered unsintered multilayer structure in a nitrogen atmosphere having a high water vapor pressure to decompose the binder contained in the green sheets and the copper paste,
A step of removing and then firing in a reducing atmosphere. 2. A ceramic multilayer wiring board according to claim 1, wherein the atmosphere for the heat treatment step of decomposing and removing the binder is a nitrogen atmosphere having a water vapor partial pressure of 0.1 to 0.5 atm. Production method. 3. A method for manufacturing a ceramic multi-layer wiring board according to claim 1, wherein the temperature of the heat treatment step of decomposing and removing the binder is lower than the sintering point of the glass ceramic.