JPS58199741A - Enamel composition - Google Patents

Abstract

PURPOSE:To obtain an enamel composition having a high softening point and superior electric characteristics and enabling the baking of paste which is baked at a high temp. on the composition by providing a special composition consisting of CaO, BaO, SrO, MgO, Al2O3, SiO2 and B2O3. CONSTITUTION:An enamel composition consisting of, by weight, 7-20% CaO, 10-18% BaO, 3-7% SrO, 3-13% MgO, 10-22% Al2O3, 20-30% SiO2 and 7- 23% B2O3 while satisfying Al2O3/SiO2=0.5-0.68 and CaO/MgO=3.2-0.11 is baked on a metallic core to form an enamel layer. Recrystallized Wallastonite and cristobalite are deposited in the layer to increase the softening temp. of the layer to >=900 deg.C, and an enameld substrate enabling the use of paste which is baked at a high temp. is obtd. The substrate can be used as a substrate for a hybrid integrated circuit with a high degree of integration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel enamel composition which enables the use of a high temperature baking paste by baking onto a metal core and which can be used as a substrate for highly integrated hybrid integrated circuits. The purpose is to make it possible to produce a hollow substrate.

Conventionally, ceramic substrates have been used as substrates for electronic circuits, allowing the use of high-temperature baking pastes that have excellent electrical properties, but these have the disadvantages of high manufacturing costs and low mechanical strength. Therefore, attempts have been made to solve the above drawbacks by using a hollow substrate in which a single layer of hollow is baked onto a metal core.

However, existing enamel substrates made of enamel compositions baked into metal cores have a low softening point of about 700°C or less, and if you try to bake a high-temperature baking paste that will not stick to ceramic substrates, it is difficult to bake at temperatures of 750°C to 900°C. A high-temperature baking paste cannot be used because the single layer of enamel becomes molten in a temperature atmosphere and reacts with the high-temperature baking paste.

Therefore, it is decided to use a low-temperature baking paste that can be baked in an atmosphere at a temperature of about 650° C. or lower.

In this case, the paste has a low melting point and high reactivity, resulting in poor electrical properties such as resistance value drift.

In addition, when trying to apply the laminated printing method to increase the degree of integration of thick film hybrid integrated circuits, the firing temperature of the overglass that forms the insulating layer is higher than the softening point of a single layer of enamel. Another drawback is that the single layer of enamel and the enamel board paste soften and react, making it impossible to form a circuit, making it impossible to perform lamination baking.

In the present invention, the composition of the enamel composition is Ca07~20wt1
%, BaO10-18% by weight, 5rO3-7% by weight, M
g03-13% by weight, AA'20310-22% by weight,
5iO2 is composed of 20-30% by weight, B2037-23% by weight, and the ratio of Al2O3 and 5102 is 0.5-0.6.
8. By setting the ratio of CaO and MgO within the range of 3.2 to 0.11, it is possible to prevent worstenite (CaO
・5i02) and cristobalite (Si(h)) are precipitated to make the softening temperature of the hollow layer higher than 900°C, thereby solving the above drawbacks. explain.

Here, A 1203 /S i 02 is “0,5~
Within the range of 068 and L7Th. hot water,. . Yo75E* *”
``*'y/: 1□□7.1, so it becomes impossible to print in microns, and if this ratio is too small, the enamel will become too vitrified during enamel firing, and the paste will react and form a circuit. This is because it becomes impossible to do so.

In addition, the reason why CaO/MgO was set in the range of A, 2 to o, tt is because if this ratio is too large, the volatile components in the patch will be too large, making batch preparation and frit manufacturing difficult. This is because if it is too much, the crystal structure will change and the expansion coefficient will no longer match.

50ffX 50ffX0.7++11 as metal core
Using an ultra-low carbon steel plate of
It was coated so as to have a thickness of .mu. and baked at about 900.degree. C. for 5 minutes to obtain a hollow substrate.

During the above firing, the enamel layer has extremely low viscosity at its initial melting point, and then rapidly increases its viscosity due to partial devitrification.

As a result of X-ray diffraction measurement of one surface of the enamel substrate obtained as described above, it was found that worstenite (CaO-5i
Recrystallization of cristobalite (SiO+) and cristobalite (SiO+) was confirmed (see attached drawing). These recrystallized minerals solidify the surface of the single layer of enamel, making it possible to use a high-temperature baking paste, and also making it possible to obtain a degree of integration equivalent to that of a ceramic substrate by laminated baking.

Further, the measurement results of the electrical properties, thermal properties, and mechanical properties of the hollow substrate are shown in Table 2.

Table 2 Also, 8 pieces of alumina substrate Kawabeito were added to the above-mentioned enamel substrate.
When baked at 50° C. for 10 minutes, the solder wettability and adhesive strength were similar to those of the alumina substrate.

As described above, the present invention makes it possible to bake a high-temperature baking paste that exhibits a significantly high softening point and has excellent electrical properties by applying and baking it on the surface of a metal core. This provides unique effects such as being able to obtain a thick-film hybrid integrated circuit with high performance.

[Brief explanation of drawings]

The drawing is an X-ray diffraction measurement result of a single layer of enamel obtained using the enamel composition of the present invention.

Claims (1)

[Claims] 1. Ca07-20% by weight, Ba010-18% by weight, 5r03-7% by weight, Mg03-13% by weight, A1
2os10-22% by weight, SiO+20-30% by weight,
82037~23% by weight, Al2O3/Si
02 from 0.5 to 0.68, CaO/MgO from 3.2 to
An enamel composition characterized in that the porosity is in the range of 0.11.