JPH06334282A - Green sheet for ceramic multilayer substrate - Google Patents

Abstract

PURPOSE:To simplify debinder process for manufacturing a substrate by using polypropylenecaronate resin, etc., for ceramic powder as main constituents and then a slurry where a material obtained by adding acryl resin as a dispersant is prepared as resin for binder. CONSTITUTION:The main constituent of binder resin is constituted by polypropylene carbonate resin or polyethylenecarbonate resin. Since the resins are completely subjected to thermal composition in air until temperature reaches 300 deg.C, debinder can be performed quickly and easily. The polypropylenecarbonate resin, etc., have relatively large molecular weight. Therefore, when a green sheet is formed only with the resins, the dispersion property of ceramic powder is poor so that the surface state of the green sheet becomes an island style or is cracked. Therefore, by adding acryl resin with a relatively small molecular weight, the dispersion property of the ceramic powder is improved to obtain the improved green sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a green sheet for a ceramic multi-layer substrate, and is particularly characterized by simplifying a debinding process for producing a substrate.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of electronic devices and the digitization of circuits, there has been a demand for high-density ceramic multilayer substrates. In particular, Ag, which is a low-impedance conductor,
Attention has been focused on a low-temperature fired ceramic substrate having a low dielectric constant and a low linear expansion coefficient, which can use Cu or a material similar thereto.

The conventional manufacturing process of a ceramic multilayer substrate is as follows.
Laminate multiple ceramic green sheets with wiring patterns printed on them, spend several tens of hours to remove (remove binder) the organic components from the green sheets, and then bake the substrate, This is done by screen-printing a conductor paste and firing the outer conductor.

Generally, the binder for the green sheet is a resin such as ethyl cellulose (thermal decomposition temperature: 350).
(° C or higher) is used, and cordierite glass ceramics and the like have been used as the ceramic powder.

[0005]

However, in the conventional manufacturing process of the above-mentioned ceramic multilayer substrate, in order to remove the organic component in the green sheet laminate, a binder removal process must be provided before the substrate baking process. This process required a very long time of several tens of hours, and its profile was also very delicate.

This is because the thermal decomposition temperature of the binder resin contained in a large amount in the green sheet is 350 ° C. or higher, and it takes a considerable amount of time and an associated electricity bill to completely remove the binder resin. It led to a significant cost increase.

It is an object of the present invention to solve the above problems and to provide a ceramic multi-layer substrate which can be manufactured at a lower cost by simplifying the debinding process for producing the substrate.

[0008]

Means for Solving the Problems In order to solve the above problems, a green sheet for a ceramic multilayer substrate of the present invention contains, as a main component, either a polypropylene carbonate resin or a polyethylene carbonate resin with respect to a ceramic powder, and an acrylic resin. Is prepared by using a slurry prepared by adding as a dispersant to a resin for binder.

[0009]

According to the above construction, the main component of the binder resin contained in the green sheet is polypropylene carbonate resin or polyethylene carbonate resin. Since these resins are completely thermally decomposed up to 300 ° C. in air, debinding can be easily performed in a short time. Since it is possible to omit the special debinding process before the substrate baking, it is possible to simultaneously perform the binder removal during the substrate baking process in the belt continuous baking furnace.

The reason why acrylic resin is added to the binder here is that polypropylene carbonate resin or polyethylene carbonate resin has a relatively large molecular weight (about 50,000), and when this resin alone is used to disperse the ceramic powder when a green sheet is molded. Since the surface properties of the finished green sheet are poor and have an island pattern or cracks, a good green sheet cannot be obtained. Therefore, by adding an acrylic resin having a relatively small molecular weight (10,000 or less), the dispersibility of the ceramic powder is increased and a good green sheet is obtained.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. Table 1 shows the composition of the slurry when molding the green sheet for a ceramic multilayer substrate in one example, and Table 2 shows the composition of the ceramic powder used at that time.

[0012]

[Table 1]

[0013]

[Table 2]

As shown in FIG. 2, a green sheet 6 having a thickness of 200 μm is formed from the slurry having the above composition by a doctor blade method and dried. Next, a via hole 4 is formed in the green sheet 6 by an NC punching device, and the via hole 4 is filled with a conductive paste and dried. Then, the inner layer conductor 2 is formed by screen printing and dried. The respective layers thus formed are thermocompression-bonded by a laminating machine to be integrated to complete a green sheet laminated body.

This green sheet laminate was subjected to a belt continuous firing furnace without a special debinding process, as shown in FIG.
120 minutes at 900 ° C with the profile shown in
The substrate is baked for 20 minutes.

Then, the outermost conductor 3 is formed on the surface of the dielectric layer 1 by a screen printing method using a conductor paste,
After drying and firing, the resistor 5 is formed by a screen printing method using a resistor paste, followed by drying and firing to complete the ceramic multilayer substrate shown in FIG.

In this embodiment, the inner layer conductor 2 is made of silver, and the outermost layer conductor 3 is made of a conductor whose main component is silver / platinum.
Further, the resistor 5 is formed of a resistor whose main component is ruthenium oxide. Table 3 shows the substrate characteristics of the ceramic multilayer substrate of this example.

[0018]

[Table 3]

In addition to the above examples, a green sheet using a slurry prepared by adding a polypropylene carbonate resin as a binder resin as a main component and adding an acrylic resin as a dispersant also simplifies the debinding process. can do.

[0020]

As described above, according to the green sheet for a ceramic multilayer substrate of the present invention, in the manufacturing process of the ceramic multilayer substrate, a belt continuous firing furnace is used for a short time without providing a special debinding process. It is clear that not only can the substrate be fired in the above-described manner and the manufacturing thereof can be easily performed, but this also contributes to cost reduction of the ceramic multilayer substrate.

[Brief description of drawings]

FIG. 1 is a sectional view of a ceramic multilayer substrate using a green sheet for a ceramic multilayer substrate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view in one manufacturing process of the ceramic multilayer substrate.

[FIG. 3] Substrate firing profile of the same ceramic multilayer substrate

[Explanation of symbols]

 1 Dielectric Layer 2 Inner Layer Conductor 3 Outer Layer Conductor 4 Via Hole 5 Resistor 6 Green Sheet

Front page continuation (72) Inventor Hiroshi Ochi 2-10, Shoucho, Takamatsu City, Kagawa Prefecture Matsushita Electronic Industry Co., Ltd.

Claims (1)

[Claims] 1. A slurry prepared by using, as a binder resin, a slurry containing, as a main component, either a polypropylene carbonate resin or a polyethylene carbonate resin and an acrylic resin added as a dispersant to a ceramic powder. Characteristic green sheet for ceramic multi-layer substrate.