JPH0294595A - Manufacture of multilayer ceramic substrate - Google Patents

Abstract

PURPOSE:To eliminate malfunctions such as warpage, disconnection, etc., and to reduce the sheet resistance value of a conductor by employing a material for raising the contraction ending temperature of conductor paste higher than that of a green sheet. CONSTITUTION:The average particle size of conductor paste is so increased as to raise the contraction ending temperature of the paste higher than that of a green sheet, or so selected as to reduce the average particle diameter of the green sheet. If the sheet resistance value of the conductor is desired to be reduced, the particle size of the paste is increased, and charging ratio is so controlled that the shrinkages of the green sheet and the paste are not so separated. Plasticizer such as organic binder or the like, solvent of toluene are added to the material powder of ceramics such as alumina powder having selected particle size, the mixture is kneaded, its slurry is formed in a sheet state, thereby forming a green sheet. Holes for viaholes are opened at the green sheet, and conductive paste having a selected particle diameter and made of Cu, Ag, Ag-Pd, etc., for wiring is printed in a predetermined circuit on the front face.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a multilayer ceramic substrate.

[Prior Art] In the production of multilayer ceramic substrates, the problem of warping or other deformation occurring due to the difference in shrinkage rate between the green sheet and the conductive paste printed on it during firing has been solved by changing the shrinkage rate between the green sheet and the conductive paste. is small. A proposal to use the material has been made in Japanese Patent Laid-Open No. 60-24095. However, in this case, during firing, the shrinkage start temperature and shrinkage end temperature of the green sheet conductor paste must be almost the same, and for this purpose, the particle sizes of the materials used for the green sheet and conductor paste must be approximately matched. Therefore, it was not possible to provide flexibility in the sheet resistance of the conductor.

[Problems to be Solved by the Invention] The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to provide a novel multilayer ceramic substrate that has not been known in the past. This is the purpose.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and uses a material that makes the shrinkage end temperature of the conductor paste higher than the shrinkage end temperature of the green sheet. The present invention provides a method for manufacturing a multilayer ceramic substrate characterized by the following.

The present invention will be explained in detail below.

In the present invention, when firing is performed at a substantially constant temperature increase rate, the smaller the average grain size of the ceramic material, the lower the shrinkage end temperature, and the larger the average grain size, the higher the shrinkage end temperature. By using this method, the shrinkage end temperature of the conductor paste is made higher than the shrinkage end temperature of the green sheet to prevent deformation such as warping of the multilayer ceramic substrate and disconnection of the conductor. The purpose is to reduce the sheet resistance of the conductor by taking advantage of the fact that the average particle diameter becomes thicker (and the shrinkage end temperature becomes higher). Note that % means weight % unless otherwise specified.

Table 1 shows the average particle diameter, shrinkage end temperature, shrinkage rate, etc. of the green sheet.

Table 2 shows the average particle size, sheet resistance value, shrinkage end temperature, and shrinkage rate of conductor pastes containing 77% Ag, 20% Pd, and 3% glass frit or crystallized glass frit.

Table 3 shows glass frit or crystallized glass frit 3.
It is the average grain size of Cu conductor paste containing %.

In addition, in Tables 2 and 3, the thickness of the conductor after firing is 8μ.
Let it be m. Here, the contraction end temperature is the point at which the volume change due to compaction of the material ends.

Shrinkage rate is the rate of change obtained by dividing the difference (L, -L, = △L) between the dimension (Lo) before firing and the dimension after firing (L, ) by the dimension before firing. It is. (△L/
L, Furthermore, as can be seen from Tables 2 and 3, it can be seen that as the average particle size of the conductive paste increases, the sheet resistance value decreases.

Furthermore, it has been found that the shrinkage rate is controlled by the filling rate of the material. That is, the higher the filling rate is, the smaller the shrinkage rate is, and the lower the filling rate is, the higher the shrinkage rate is. Therefore, in order to control the filling rate of the material, in the case of green sheets,
The filling rate may be controlled by the amount of binder, and in the case of a conductor paste, the filling rate may be controlled by the amount of vehicle added to impart printability.

The multilayer ceramic substrate according to the present invention is manufactured as follows. The present invention prevents deformation of the multilayer ceramic substrate and disconnection of the conductor by making the shrinkage end temperature of the conductor paste higher than the shrinkage end temperature of the green sheet when fired at a constant temperature increase rate. In this case, the average particle size of the conductor paste is increased or the average particle size of the green sheet is decreased so that the contraction end temperature of the conductor paste is higher than the green sheet contraction end temperature. If it is desired to reduce the sheet resistance value of the conductor, the particle size of the conductor paste may be increased, and the particle size of the green sheet may be selected accordingly so as to satisfy the above conditions. Also, the filling rate is controlled as described above so that the shrinkage rates of the green sheet and the conductor paste do not differ too much. Raw materials for ceramics such as alumina powder and glass frit having particle sizes selected in this manner are combined with organic binders such as butyral resin and acrylic resin, plasticizers such as dibutyl phthalate, dioctyl phthalate, butyl-benzyl phthalate, and toluene. , a solvent such as alcohol is added and kneaded to create a slurry. Then, the slurry is formed into a sheet shape to create a so-called green sheet. Holes for via holes etc. are made in the green sheet, and Cu, Ag, Ag-P for wiring etc. are made on the surface.
A conductive paste having a particle size selected as described above, such as d, is printed on a predetermined circuit. At this time, Cu was placed in the via hall.
, Ag, Ag-Pd, etc. are filled. Next, a predetermined number of these printed green sheets are stacked one on top of the other, stacked by thermocompression bonding, and fired at a temperature of 1000° C. or lower to form a multilayer ceramic substrate. The multilayer ceramic substrate manufactured in this manner has circuits laminated in multiple layers with an insulating substrate interposed therebetween.

Although the present invention has been described with respect to multilayer ceramics,
Includes single-layer ceramic substrates and other ceramic electronic components.

[Example] Example 1 1. Preparation of green sheet Alumina 60, glass frit (5iO-Al□03-
(Ca0-Pb0 system) 40 was mixed in a ball mill for 30 minutes.

Next, an organic binder acrylic resin, dibutyl phthalate as a plasticizer, and toluene as a solvent were added to these and kneaded to prepare a slurry having a viscosity of 1000 to 3000 CPS.

Next, this slurry was formed into a sheet with a thickness of about 0.2 mm, and then dried at 70° C. for 2 hours to produce a green sheet. The average particle size of the glass frit used for green sheet production, the amount of binder, and the temperature increase rate of 3°C/rnin are 1
Table 1 shows the shrinkage end temperature and shrinkage rate when baked at 000°C for 6 hours.

2. Preparation of conductor paste (1) A mixed powder of 3% crystallized glass frit, 77% silver, and 20% palladium, and an organic vehicle consisting of ethyl cellulose resin and butyl calpitol to impart printability are placed in an alumina magnetic mortar. The mixture was mixed for 30 minutes in a vacuum chamber, and then dispersed using three rolls to prepare a conductive paste.

(2) As conductor powder: 3% glass frit, 9% copper powder
Table 3 shows the average particle size, shrinkage end temperature, shrinkage rate, and sheet resistance value of the conductor paste produced in the same manner as described above using 7%.

3. Preparation of multilayer ceramic substrate using silver-palladium as a conductor A test module was prepared to investigate the presence or absence of warpage and disconnection using the combination of the green sheet shown in Table 1 and the conductive paste shown in Table 2.

The manufacturing conditions are as follows.

Substrate size = 100mm x 100mm square printing pattern = 250μ, line width 250μ pitch through hole filling =
Number of horizontal wiring and connection layers filled in 200 holes = 20 layers per sheet Lamination method = 90℃ x 5 minutes Pressure firing temperature = 850℃, 6 hours, air atmosphere results are shown.
4. As shown in Table 4, in the combinations (Samples No., 5.No., 6.No., 7) where the shrinkage end temperature of the conductor paste is higher than the shrinkage end temperature of the green sheet,
No defects such as warping or wire breakage were observed.

4. Fabrication of a multilayer ceramic substrate using copper as a conductor (copper conductor) A test module was fabricated to investigate the presence or absence of warpage and disconnection using the combination of the green sheet shown in Table 1 and the conductive paste shown in Table 3. did. The manufacturing conditions are as follows.

Substrate size = 100mm x 100mm square printing pattern = 750μ, line width 150μ pitch through hole filling =
Number of horizontal wiring and connection layers filled in 150 holes = 20 layers per sheet Lamination method = 90℃ x 5 minutes Pressure firing temperature = 900℃, 6 hours, nitrogen atmosphere Results are shown below.
5. As shown in Table 5, the combinations where the shrinkage end temperature of the conductor paste is higher than the shrinkage end temperature of the green sheet (Sample No., 5. No., 6. No.
7), no defects such as warping or wire breakage were observed.

Table 1 (Green sheet) Table 2 (Ag, PD conductor paste) Table 3 (Cu conductor paste) [Effects of the invention] The present invention produces a multilayer ceramic substrate with excellent reliability without defects such as warping and disconnection. In addition to providing a method, the excellent effect of reducing the sheet resistance value of the conductor is also recognized, and its industrial value is great.

Table 4 (Using silver-palladium conductor) Table 5 (using copper conductor)

Claims (1)

[Claims] A method for manufacturing a multilayer ceramic substrate, comprising using a material that makes the shrinkage end temperature of a conductive paste higher than the shrinkage end temperature of a green sheet.