JPH0997703A - Resistive paste self-contained in low temperature baking substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the title resistive paste self-contained in low temperature baking substrate producing less change in the resistance value even if baking step is repeated. SOLUTION: Within the title resistance paste self-contained in low temperature baking substrate mainly comprising ruthenium oxide and glass, 1-5wt.% of bismuth oxide, copper oxide, manganese oxide in endomictic or mixed state is additionally contained in 99-95wt.% of ruthenium oxide and glass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance paste incorporated in a low temperature firing substrate having a firing temperature of 1000.degree.

[0002]

2. Description of the Related Art With the recent miniaturization of electronic devices, the demand for high-density integration of electronic circuits has increased, and ceramic substrates for electronic devices have multiple layers and fine pitch circuits. The demand for bare mounting of chips is increasing. In order to meet these requirements, Au, Ag, and Cu having a low conductor resistance and capable of fine patterning
A ceramic substrate that can be fired at a temperature at which it can be fired at the same time as a conductor such as 1000 ° C. is required.

Conventionally, alumina or glass epoxy substrates have been used as substrates for electronic equipment. However, the coefficient of thermal expansion of the glass epoxy substrate is 50 × 10 ⁻¹ /
It is unsuitable for satisfying the above requirements, such as a large temperature of about 0 ° C and a poor thermal conductivity as compared with alumina. Further, since alumina requires a high temperature of about 1600 ° C. for firing, W or Mo having a relatively high conductor resistance must be used as an internal conductor when multilayering is performed. There was a limit to fine patterning.

In order to cope with such a problem, Au, Ag, Cu or the like having a low conductor resistance, particularly Ag and Ag alloy which are advantageous in terms of cost, can be used as the inner conductor, and the thermal conductivity is high. Development of a low-temperature fired substrate made of a composition of glass, an inorganic filler such as a metal oxide, which is superior to that of a glass epoxy substrate, is under way.

Further, since the low-temperature fired substrate can be fired at a temperature of 1000 ° C. or lower, it has a feature that a functional component such as a ruthenium oxide-based resistor can be incorporated inside by simultaneous firing. However, since the resistance thus obtained is obtained by co-firing, it is impossible to modify the resistance value after firing, and the resistance value changes with the changes in the process of manufacturing the low temperature firing substrate. There was a problem of doing. For example, in the case where only the conductor is formed on the surface by the paste and the case where the resistor is also formed, in the latter case, the number of times of re-baking (for baking the surface conductor and the resistor) after simultaneous baking becomes larger. Therefore, since the resistance value of the internal resistance changes depending on the number of times of this re-baking, it is extremely difficult to match the final resistance value.

[0006]

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide a resistance paste for embedding in a low temperature firing substrate, which has a small change in resistance value even if firing is repeated by adding a specific oxide to the resistance paste. It is what

[0007]

The present invention for achieving the above object provides a resistance paste containing ruthenium oxide and glass as main components, wherein bismuth oxide, copper oxide and manganese oxide are added to ruthenium oxide and glass. Alone,
Alternatively, it is a resistance paste for embedding in a low temperature firing substrate, which is characterized by being added and contained in an amount of 1 to 5% by weight in a mixed state.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Generally, in order to manufacture a low temperature fired substrate, first, a green sheet made of glass, an inorganic filler, a resin and the like is prepared by using a doctor blade method or the like,
The built-in conductor and resistor paste are formed by printing. The obtained green sheets are laminated and co-fired to obtain a ceramic substrate having an internal circuit. The surface conductor is then printed and further fired. In order to further form a resistor on the surface, a resistor paste is further printed and fired. Therefore, the number of times of re-firing after simultaneous firing differs depending on the number of circuits and resistors formed on the surface.

In the case of a built-in resistance paste, it is difficult to correct the resistance value after simultaneous firing, and in order to obtain a built-in resistor having a resistance value as designed, it is necessary to grasp the change in resistance value due to re-firing and then incorporate It is necessary to determine the composition of the resistance paste.
Further, if the change in resistance value due to firing is large, it is necessary to change the composition of the resistance paste for each circuit formed on the surface, which raises the problem of increased cost and reduced design flexibility. Therefore, there is a demand for a paste for embedding which has a small change in resistance value due to re-firing.

As a result of various researches on an embedding paste which immediately meets such requirements, in an embedding paste mainly composed of ruthenium oxide and glass, bismuth oxide was added to 99 to 95% by weight of ruthenium oxide and glass. It was found experimentally that the change in resistance value due to re-baking can be extremely reduced by adding 1 to 5% by weight of copper oxide, copper oxide, and manganese oxide individually or in a mixed state, and the present invention has been completed. .

In the above-mentioned paste for embedding of the present invention, when the content of bismuth oxide, copper oxide and manganese oxide to be added to the ruthenium oxide-glass paste is less than 1% by weight based on the total amount of the paste. However, the effect is not sufficient, and when it exceeds 5% by weight, the change of the resistance value becomes rather large, which is not preferable.

[0012]

EXAMPLES Examples of the present invention will be described below. It goes without saying that the present invention is not limited to this embodiment.

SiO ₂ --Al ₂ O ₃ --B ₂ O ₃ --ZnO
-CaO based crystallized glass powder _(SiO 2: 35 wt%,
Al ₂ O ₃ : 25% by weight, B ₂ O ₃ : 8% by weight, Zn
O: 19% by weight, CaO: 13% by weight) and Al ₂ O ₃ powder were mixed in a weight ratio of 62:38 by using a ball mill to obtain a composition for low temperature firing substrate. The Al ₂ O ₃ powder used here had an average particle size of 0.5 to 1 μm.

48 parts by weight of butyral resin, 70 parts by weight of dibutyl phthalate as a plasticizer, 50 parts by weight of isopropyl alcohol and 50 parts by weight of methyl ethyl ketone as a solvent were added to 100 parts by weight of the composition for a low temperature fired substrate thus obtained. Ball mill mixing was performed for a time to prepare a slurry, and a green sheet was produced on a PET film by a doctor blade method.

Next, ruthenium oxide, glass powder having the composition shown in Table 1 and each oxide (bismuth oxide, copper oxide, manganese oxide) were mixed at the ratio shown in Table 2, and 100 parts by weight of the mixture was added. On the other hand, 35 parts by weight of a terpineol solution of ethyl cellulose as a vehicle was added and kneaded with a three-roll mill to prepare a uniform paste. In Table 2, samples Nos. 2 to 10 and Sample No. 14 are paste examples in the composition range of the present invention, and Sample Nos. 1 and 11 to 13 are comparative paste examples outside the composition range of the present invention. is there.

[0016]

TABLE 1 Ingredient wt _{(%) SiO 2: 33 Al} 2 O 3: 24 B 2 O 3: 9 ZnO: 19 CaO: 15

[0017]

[Table 2] Composition (% by weight) Sample number RuO ₂ glass Bi ₂ O ₃ CuO Mn ₃ O ₄ Remarks ────────────────────────── ─────────── 1 88 12 0 0 0 Comparative Example 2 87.5 11.5 1 0 0 Invention Example 3 87.5 11.5 0 1 0 Invention Example 4 87.5 11.5 0 0 1 Inventive Example 5 86.5 10.5 3 0 0 Inventive Example 6 86.5 10.5 0 3 0 Inventive Example 7 86.5 10.5 0 0 3 Inventive Example 8 85.5 9.5 5 5 0 Invention Example 9 85.5 9.5 0 0 5 0 Invention Example 10 85.5 9.5 0 0 5 Invention Example 11 84.5 8.5 7 0 0 Comparative Example 12 84.5 8.5 0 7 0 Comparison Example 13 84.5 8.5 0 0 7 Comparative Example 14 86.5 10.5 2 1 0 Invention Example

Next, a silver paste was printed as an electrode on the above green sheet and dried at 120 ° C. for 20 minutes to prepare a green sheet with an electrode. Then, the resistance paste obtained by the method described above was screen-printed on the above-mentioned green sheet with electrodes using a printing pattern of 1 mm × 1 mm, and dried at 120 ° C. for 20 minutes.

The three green sheets with the conductor and the resistor formed as described above are sandwiched in the center and pressure-bonded at 60 to 80 ° C. at 100 kgf / cm ² for 5 minutes, and then, a predetermined amount is obtained. The sheet was cut into a size, and baked at a maximum temperature of 875 ° C. and a holding time at the maximum temperature of 20 minutes. Then, a silver electrode for measuring electric characteristics was provided on the uppermost layer, and the electric characteristics of the internal resistance could be measured by connecting the electrode and the internal electrode with a via hole using a silver paste.

The sample thus constructed was repeatedly fired twice under the firing process conditions of a total heating time of 30 minutes and a maximum temperature of 850 ° C. for 9 minutes. Was measured, and the obtained results are shown in Table 3. As a result of observing the cross section of the obtained sample with an optical microscope, the film thickness of the built-in resistor was about 10 μm.

[0021]

[Table 3] Sample number Resistance value (KΩ / sq) Resistance value change rate (%) Remark ───────────────────────────── ─── 15-7.4 Comparative Example 2 4.1-3 Invention Example 3 6.9-2 Invention Example 4 4.1-2.8 Invention Example 5 3 0 Invention Example 6 7.5 0.5 Invention Example 7 3.5-0.1 Invention Example 8 2.3 2.5 Invention Example 9 7.7 3.1 Invention Example 10 3.1 2.9 Comparative Example 11 2.2 6.5 Comparative Example 12 7. 8 7.2 Comparative Example 13 3 6.2 Comparative Example 14 4.7-0.1 Invention Example

From the results shown in Table 3, bismuth oxide, copper oxide, and manganese oxide were added to the resistance paste in an amount of 1 to 1 by mixing bismuth oxide, copper oxide, and manganese oxide with respect to 99 to 95% by weight of glass.
The pastes (Sample Nos. 2 to 10 and Sample No. 14) according to the present invention containing 5 wt% added can suppress the rate of change in resistance value within ± 5% even when re-baking is performed. On the other hand, the paste containing no bismuth oxide, copper oxide or manganese oxide (Sample No. 1) and the paste added even in an amount that deviates from the scope of the present invention (Sample Nos. 12 to 13) are It can be seen that the rate of change is extremely large. That is, according to the present invention, it can be seen that a resistance paste for embedding in a low temperature fired substrate with a small change in resistance value can be obtained.

[0023]

As described above, the resistance paste of the present invention does not significantly change its resistance value even if it is re-fired, so that it is very effective in design as a low-temperature firing substrate built-in resistance paste. be able to.

Claims (1)

[Claims] 1. In a resistance paste containing ruthenium oxide and glass as main components, 1 to 5% by weight of bismuth oxide, copper oxide and manganese oxide are added to ruthenium oxide and glass individually or in a mixed state. A resistance paste for embedding in a low-temperature fired substrate, characterized by being contained.