JPS63155695A - Manufacturing method of multilayer board with capacitor - 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 Field of Industrial Application The present invention relates to a method of manufacturing a multilayer wiring board with capacitors.

Conventional Technology Conventionally, conductor paste materials used in ceramic wiring boards include noble metals such as Au and Au-Pt.

Ag-Pt, Ag-Pd, etc. are W as base metals.

There are high melting point metals such as Mo and Mo-Mn. The former Au,
Noble metal pastes such as Au-Pt, Ag-Pt, and Ag-Pd can be baked in air and have high reliability, but have the problem of high cost. Also, the latter W
, M o , M o -M n etc. are about 1600°C, that is, above the green sheet sintering temperature (approximately 1500°C), so it is easy to make multilayers because they are fired at the same time, but they have high electrical resistance and cannot be used in a reducing atmosphere. It has problems such as being dangerous because it requires firing inside the conductor, and it also has the disadvantage that the conductor surface cannot be directly soldered, so it is necessary to plate the conductor surface with Ni etc., so it is widely used in the industry. Uke is the reason for not being accepted.

Therefore, in recent years, attention has been focused on Cu, which is inexpensive, has low electrical resistance, and has good solderability, and efforts are being actively made in various fields to put it into practical use. Here, an example of a method for manufacturing a ceramic wiring board using Cu paste will be described. Screen printing is performed using Cu paste on a sintered substrate such as alumina to form a wiring pattern, and after drying, the Cu is not oxidized at a temperature below the melting point of Cu and the organic binder in the conductor paste is fully absorbed. The process involves firing in a nitrogen atmosphere with controlled oxygen partial pressure so that it is decomposed and removed. Furthermore, in ceramic multilayer substrates using Cu paste, an insulating paste is further printed, and the Cu paste described above is printed.
The paste and insulating paste are printed and fired repeatedly to form multiple layers.

Problems to be Solved by the Invention However, multilayer substrates using Cu paste generally have the following problems. That is, in order to obtain a Cu electrode, it is necessary to perform firing in nitrogen, so a resistor and dielectric material that is sufficiently stable even in nitrogen is required. However, at present, these materials are not sufficient for practical use, and efforts are being made in various fields to develop these materials that can be fired with nitrogen. In particular, for capacitor materials, new types of material systems have been proposed that can be fired in neutral or reducing atmospheres such as N2. For example, P. Thayer, RIMEX COBORAISIDIN I, M.C. 1984 Tokyo pl 06-p 11
1 (P, 5ayers, Remex Corporation
ation, IMC, 1984 TOKYO, pl
o 6-p 111). A system is presented in which these materials can be integrated with copper paste. However, these material systems also have some problems.

This is because BaTiO3-based materials and pb perovskite-type capacitor materials are often reduced by heat treatment in an N2 atmosphere and lose their dielectric properties.Also, even when using special material systems, materials with a low dielectric constant or dielectric properties cannot be obtained. loss,
At present, only inadequate temperature characteristics can be obtained. Furthermore, when firing the capacitor paste, it is difficult to remove the organic binder in the paste.

Residual binder remains in the form of carbon, resulting in insufficient dielectric properties. Because of the problems mentioned above, it is thought that it will take many years before it can be put into practical use.

On the other hand, as a new proposal, a material has been developed that does not become a semiconductor even when fired at an oxygen partial pressure of 104 to 10'3 atmospheres and has sufficient insulation resistance as a capacitor.

For example, Wai, Sakabe, Kei, Minai, Kei.

Wakino, Japanese, Journal, Apolide.

Physics (Y, 5akabe, K, Min
ai.

K, Wakino, Jap, J, Appl
, Phys, ) 20 (suppl, 20-43,
147 (1981).

According to this method, the commonly used B aTr Oa
It has been shown that firing can be performed with a lower amount of oxygen compared to yarn materials. However, in actual firing, the oxygen partial pressure of 10 to 104 atm is difficult to control, and the upper layer Cu
It is also complicated to control the oxygen partial pressure when firing the electrodes.

Means for Solving the Problems In order to solve the above-mentioned problems of multilayer substrates with added capacitors, the present invention forms a capacitor using a capacitor material and an electrode paste that can be fired in air. Then, the via holes are filled with an insulating paste mainly composed of a powder made of a mixture of glass and ceramics with a softening point of 600°C or less, so that the capacitor material part is not exposed to the outside and the circuit pattern can be connected to the upper wiring part. Perform printing on the entire surface except for the part that forms the . Finally, a pattern is printed on the upper layer using Cu paste, and N2 is heated at a temperature of 800℃ or higher.
Fire. At this time, after printing the insulating paste, the Cu paste is printed, but it is also possible to form a multilayer structure by repeatedly printing the insulating paste and the Cu paste.

Function The present invention makes it possible to protect the capacitor material, which is reduced at high temperatures, from the N2 atmosphere by using the insulating paste having the above-mentioned structure, and to exhibit the capacitor performance. That is, when a capacitor forming part that has been fired once in air is covered with an insulating paste and then fired in N2,
The glass component in the insulation paste softens at around 600℃,
Since the capacitor part is sealed, B a T i
Oa.

Capacitor materials such as pb perovskite systems are not reduced.

Then, the insulating layer is sintered by further maintaining the temperature at a high temperature to crystallize the insulating material and react with ceramics such as alumina. Further, printing and firing of Cu paste on the upper layer are also performed at the same time. At this time, the insulating material does not soften because it has a high softening point due to crystallization or reaction with the ceramic. The hybrid IC with a capacitor of the present invention obtained as described above has the characteristics of capacitor materials suitable for firing in air, such as BaTiO3 and PB perovskite (accurate capacitor formation, high dielectric constant).

High reliability, etc.) can not only be used as is, but also
In addition, since Cu can be fired at high temperatures, highly reliable Cu metallization can be obtained.

Furthermore, by repeating printing of Cu paste and insulating paste a desired number of times, multilayering can be easily achieved. Examples are described below.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

A lower conductor pattern for a capacitor was formed on the surface of a 96% Al2O8 substrate using Ag/Pd electrode paste (Dupont 6120) by screen printing.
Firing was carried out in air in a Metschbelt furnace at a temperature of 50° C. (peak time 10 minutes). This state is shown in FIG. 1 (al).

In the figure, 1 is an alumina substrate, and 2 is an Ag/Pd electrode. Next, add 2 parts of the capacitor forming paste shown in Table 1.
Printing was dried (120°C for 10 minutes) using a screen with an emulsion thickness of 50 mesh and 5 μm, and then dried at 850°C (
The mixture was fired in air in a Metschbelt furnace with a peak time of 10 minutes.

(in Figure 1).

Table 1 Capacitor Paste Used Next, the same Ag/Pd electrode as above constitutes the upper electrode of the capacitor. This is as shown in FIG. 1(C). The firing conditions at this time are also the same as those for the conductor and capacitor described above.

Furthermore, borosilicate glass (#7059 manufactured by Corning Inc.) was crushed to have an average particle size of 1.8 μm, and 50,150 wt% of alumina (average particle size: 0.3 μm) powder was mixed, and a solvent containing an organic binder was added. The mixture was kneaded using corrugated rolls to form a paste. This insulating paste is then printed so as to cover the capacitor portion, leaving a predetermined via forming portion. The printing conditions were 250 mesh and 10 μm emulsion thickness.

At this time, in order to completely protect the resistor from the N2 atmosphere, printing should preferably be repeated two or more times to reduce the probability of phenomena such as pinholes during printing. Zero-order Cu paste (Dupont #9153) An electrode pattern is formed using the screen printing method.

The product prepared as described above was placed in nitrogen (02 amount 11
00 pp or less) at 900°C and a peak time of 10 minutes in a Mesoschubert.

02 at this time? It is better to have the M degree as low as possible, but considering the metallization of decomposed Cu in the organic binder, it should be 10 to 5.
The most desirable value is about 0 ppm.

A cross-sectional view of the substrate obtained as described above is shown in Fig. 1(d).
Shown below. 4 is an upper electrode, 3 is a capacitor section, 5 is an insulating layer, and 6 is a Cu electrode.

Then, a comparison was made with the dielectric properties of the capacitor paste shown in Table 1. The conventional method is the result of fabrication in air using an Ag/PD electrode, and the method of the present invention shows the characteristics after further forming an insulating layer thereon and forming a Cu electrode. The results for both are shown in Table 2.

Table 2: As is clear from the table of comparison results with the in-air firing method, the characteristics of the capacitor treated in air did not change significantly even with the subsequent multilayering of Cu, and the dielectric characteristics were maintained.

In the present invention, borosilicate glass was used as the insulating paste.
Needless to say, it is sufficient that the material has a softening point of 00° C. or lower and does not contain components that are reduced in a nitrogen atmosphere at 600° C. or higher. Also, although alumina is used as the ceramic material, it goes without saying that any material that reacts with glass and has a high softening point when fired at about 900°C is sufficient.

Further, since Ag forms a eutectic with Cu, it is not appropriate to raise the firing temperature too much, but if an Ag/Pd alloy is used, there is no problem and around 900°C is optimal.

Effects of the Invention The present invention is aimed at incorporating a capacitor into a hybrid IC using Cu and a copper multilayer substrate.
This provides an effective method for adding capacitor materials that can be fired in air.

That is, by sealing the capacitor forming part with an insulating paste, the capacitor material is protected from the N2 atmosphere, and it is possible to bake Cu at high temperature without deteriorating the quality. Furthermore, it is possible to easily form multiple layers at the same time, so it can be said to be an extremely effective invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating the manufacturing method of a multilayer board with capacitors obtained by the present invention, (al is a capacitor lower conductor formed, (bl is a capacitor paste formed), (C1 is a capacitor upper conductor) FDL is a multi-layered part made of insulating paste and copper paste.■...Alumina substrate, 2...Lower conductor Ag/Pd, 3... ...Capacitor material, 4...
...Top conductor, 5...Insulating layer, 6...
・Cu conductor. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1

Claims (1)

[Claims] A lower conductor pattern is formed on a ceramic substrate with a conductor paste made of conductor powder containing at least one of Au, Ag, and Pd, and after baking in air, a capacitor paste made of capacitor material powder is printed and placed in the air. firing and then printing the upper conductor with the conductor paste,
The capacitor portion is not directly exposed to the outside and the desired upper and lower conductor portions are formed using an insulating paste mainly composed of a mixed powder of glass and ceramic filler having a softening point of 600° C. or lower. Printing is performed on the entire surface except for the via hole part that can be connected to the part, and then a desired circuit pattern is formed with copper paste on the insulating pattern, and the insulating paste printing and copper paste printing are repeated a predetermined number of times. The oxygen concentration is 100p
1. A method for manufacturing a multilayer board with a capacitor, comprising the step of firing at a temperature of 800° C. or higher in a nitrogen atmosphere of pm or less.