KR910000995B1 - Low Temperature Fired Ceramics - Google Patents

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Low Temperature Fired Ceramics

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to glass-ceramic substrate materials, and to novel low-temperature firing ceramics, which are manufactured through low temperature firing, and which are suitable as materials for multilayer circuit boards.

Recently, in the electronics industry, the circuit elements used in the electronic devices have been developed into high-integration and high-speed circuits such as LSI and VLSI in accordance with the trend of miniaturization, high performance, high functionality, and low cost of electronic devices. Electronic circuit boards for mounting circuits are also required to develop materials that meet high speed and high density.

In general, in order to be used as a circuit board material, electrical and physical properties such as high thermal conductivity, low dielectric constant and low dielectric loss, high reliability, thermal expansion coefficient compatibility with silicon, heat resistance, chemical safety and economic efficiency are required. Alumina-based materials are widely known as ceramics for IC circuit boards which are currently used as materials satisfying some properties (solid state tech. 14 (1). P40, 1971).

The Al ₂ O ₃ content of this alumina-based substrate material is 92-96 wt% and is calcined at a temperature of 1500-1600 ° C., with a dielectric constant (ε) of 10.5-12 and a dielectric loss (tanδ) of 2 × 10 ^{−3 to} 5 × 10 ^{− 3} , Volume resistivity (ρ) 2 × 10 ^{13 to} 1 × 10 ¹⁴ (Ω-cm), coefficient of thermal expansion 7.0 × 10 ^{-6 to} 7.5 × 10 ^-6 / ℃, resistance temperature 3000 (kg / ㎠), surface roughness 1.0 -2.0 (μRa) is shown.

However, since the alumina substrate material is fired at a high temperature of 1500 ° C., the wiring conductor used on the substrate must also use a metal having high resistance such as Mo, W, Mo-Mn, etc., which has a relatively high melting point. Since the reducing atmosphere must be maintained to prevent oxidation of the substrate, there is a problem in terms of high density and low price of the substrate material.

(T : 1cm당 신호전달지연시간)의 관계식에서 알 수 있는 바와 같이 신호전달지연시간에 상당한 영향을 미침에 따라 저유전율을 갖는 것이 바람직한 바, 상기 알루미나계 기판재료의 유전율은 최대 10정도의 값을 지님으로써 기판재료로서는 큰 값을 나타낸다.On the other hand, in the substrate material, the dielectric constant ε is T = 33.3 ×

As can be seen from the relationship of (T: signal propagation delay time per cm), it is desirable to have a low dielectric constant as it significantly affects the signal propagation delay time. The dielectric constant of the alumina substrate material is a value of about 10 at most. It has a large value as the substrate material.

In addition, if the dielectric loss tanδ of the substrate material is large, the electromagnetic field is converted into thermal energy in the dielectric layer around the wiring by the signal current, which adversely affects the signal loss, and the temperature of the substrate is increased by the thermal energy, resulting in malfunction of the IC chip or It is preferable that the dielectric loss of the substrate material is as small as possible as it causes breakage, but the dielectric loss of the alumina-based substrate material has a relatively large value, which causes problems in the use of high-speed circuit board materials. The high resistance of W, Mo-Mn) has a problem of high speed and high density of the circuit.

As a recently developed material for solving the problems of such alumina-based substrate material, a low-temperature fired glass-ceramic substrate based on borosilicate glass is known (IEEE, Transaction on Components Hybrids, and Manufacturing Technology, Vol CHMT-6, No 4, P382, 1983).

However, the glass-ceramic substrate material has an advantage of low dielectric constant of borosilicate glass, which is a main component. However, when the boron component is excessively contained, boric acid is released by reacting with moisture in the air, which results in weak water resistance.

Accordingly, the present invention was developed to improve the problems associated with the conventional alumina-based substrate material and borosilicate glass-ceramic substrate material. The present invention is not only capable of low-temperature firing but also provides a multilayered, miniaturized and low-cost circuit board. It is an object of the present invention to provide a low-temperature firing ceramic.

The glass-ceramic substrate material of the present invention exhibits low dielectric constant, low dielectric loss, and low coefficient of thermal expansion, and has excellent water resistance and strength, compared to conventional alumina substrate materials.

In addition, the substrate material of the present invention uses a low-resistance and relatively inexpensive material such as Ag, Ag-Pb, Cu, Ni, etc. as the internal electrode, so that the generation of noise is small, signal transmission delay resolution, and high speed are possible. It is characterized by a material.

Such a material of the present invention is prepared by mixing a glass composition and a ceramic composition (Al ₂ O ₃ ) at a predetermined ratio and baking at a low temperature. Specifically, CaO 5-28 wt% and Al ₂ O ₃ 0-15 wt% Al ₃ O ₃ powder of 55-75 wt% glass powder consisting of 5-15 wt% BaO, 40-50 wt% SiO ₂ , 5-10 wt% ZnO, 2-25 wt% B ₂ O _3, and 10 wt% or less unavoidable metal oxide It is a low-temperature firing ceramics manufactured by low-temperature firing a magnetic composition having a composition of 45-25wt% at 900-1000 ℃.

The reason for numerical limitation about the containing component of this invention substrate material is as follows.

SiO ₂ : 40-50wt%

If the content of SiO ₂ is less than 40wt%, it is disadvantageous in terms of mechanical strength and chemical stability and the sintering temperature is high.If the content is more than 50wt%, the volume resistivity is reduced by the movement of the conductor paste. High density wiring is difficult and thermal expansion coefficient is increased.

Al ₂ O ₃ : 0-15wt%

Al ₂ O ₃ is an element that greatly affects the strength of the substrate. If the content exceeds 15wt%, the melting temperature of the glass composition material is increased and the melting temperature is increased. The lower the content of Al ₂ O _3, the lower the strength.

CaO: 5-28wt%

When the CaO content is less than 5wt%, the coefficient of thermal expansion and the electrical insulation are low, and when it exceeds 28wt%, devitrification easily occurs during the manufacture of glass powder, and when the substrate is fired, crystallization starts at low temperature, making it difficult to manufacture a dense sintered body. Do.

BaO: 5-15wt%

When the content of BaO is less than 5wt%, the mechanical strength is lowered and the surface roughness is increased.

B ₂ O ₃ : 5-25wt%

When the content of B ₂ O ₃ is less than 5wt%, the softening point of the glass becomes high, so that low temperature firing at 1000 ° C or less is difficult, and the surface state is also lowered. As a result, the molding state cannot be maintained.

ZnO: 5-10wt%

ZnO is an element added as a nucleating agent of the glass composition, the content of which is less than 5wt%, the nucleation is not active, and when it exceeds 5wt%, the coefficient of thermal expansion and dielectric loss is significantly increased.

Metal compound: 10wt% or less

Metal compounds incorporated in the glass powder are Na ₂ O, K ₂ O, Fe ₂ O ₃ , PbO, SrO ₂ , TiO ₂ and MgO. These oxides are either incorporated into the raw materials themselves or inevitably contained in the production of glass compositions. Although these metal oxides contain less than 10wt%, they do not need to be removed because they do not greatly affect the properties of the substrate material, but the sum of these elements is 5wt because Na ₂ O, K ₂ O and PbO adversely affect the electrical properties. Should be kept below%.

Glass Powder: 55-75wt%

The glass powder is obtained by mixing the SiO ₂ , Al ₂ O ₃ , CaO, BaO, B ₂ O ₃ , and ZnO metal compounds in a predetermined blending ratio, heating at 1450 ° C. for 5 hours, vitrifying, and then quenching by rapid cooling. The reason for limiting the numerical value of this glass powder is explained below for the reason for limiting the ingredients for the alumina powder.

Alumina Powder: 25-45wt%

The reason for limiting the glass powder to 55-75wt% and the alumina powder to 25-45wt% in the composition ratio of the magnetic composition is when the content of the alumina powder is 45wt% or more, that is, the glass powder content is 55wt% or less. Requires a firing temperature of at least 1000 ° C. That is, at the temperature of 1000 degrees C or less, manufacture of the compact sintered compact which is required as a substrate material becomes impossible. On the other hand, when the content of alumina powder is 25wt% or less, that is, the content of glass powder is 75wt% or more, it is possible to bake at a temperature of 900 ° C or less, but the range of the firing temperature is very narrow, and the deformation and fusion of the sintered body This results in an undesirable result and makes it impossible to obtain a good substrate material.

The substrate material of the present invention having such a component and composition range is manufactured by the following method.

First, raw oxides such as CaCO ₃ , SiO ₂ , Al ₂ O ₃ , ZnO, BaCO ₃ , H ₃ BO ₃ are accurately weighed and mixed at a predetermined ratio, and then the mixed powder is mixed at a temperature of 1450 ° C. for 5 hours. Vitrified over and rapidly cooled to prepare glass powder. The glass powder is adjusted to 55-75wt%, mixed with a predetermined amount of alumina powder, pulverized and dried, and then press-molded by adding a binder to the dried powder, followed by firing at 900-1000 ° C. The low temperature calcination ceramics of the invention are produced.

In particular, the magnetic composition of the present invention is capable of simultaneous firing at 900-1000 ° C. using Ag, Ag-Pb, Cu, Ni, Au, etc. as a conductor circuit in an air or non-oxidizing atmosphere, and also the magnetic composition of the present invention. In order to use as a multilayer circuit board, materials such as Cu, Ni, Ag, Ag-Pd can be used as the inner conductor, and Cu and Ni can be used as the circuit conductors and fired in a nitrogen gas atmosphere.

In addition, the Ag, Ag-Pd, Cu conductor material has a specific resistance of less than 1/10 of the Mo used in the conventional alumina-based substrate material, so that the wiring can be further refined as well as the sintering temperature. In addition, since the low temperature is less than 1000 ℃ there is an advantage that the diffusion reaction of the wiring conductor does not occur.

On the other hand, the effect of the substrate material of the present invention, the coefficient of thermal expansion is 5 ~ 6 × 10 ^-4 / ℃ significantly lower than that of the conventional alumina-based multilayer substrate, and can be directly bonded to the LSI chip, the dielectric constant (ε) and dielectric loss are 5-9 (1 MHz) and 1-10 × 10 ⁻⁴ , respectively, which are lower than those of the alumina-based substrate material, so that high-speed response of the signal at high frequency is possible.

In addition, the ceramics of the present invention have a specific gravity less than that of conventional alumina-based multilayer boards (2.8-3.1 g / cm 3) for easy handling and 0.4-0.5 (μRa) of half of alumina in surface roughness. In addition to being advantageous in this regard, it is possible to use a resistive conductor material such as Ag, Cu, Au, etc., which is particularly suitable for high speed and high density of circuit boards.

On the other hand, the present invention can obtain a compact sintered body by firing at a low temperature of less than 1000 ℃ can be usefully used in heat-resistant industrial parts, tableware, ornaments and the like, such as a multilayer circuit board.

Below. An embodiment of the present invention will be described.

Example 1

CaCO ₃ 87g, SiO ₂ 120g, Al ₂ O ₃ 27g, ZnO 21g, BaCO ₃ 30g, H ₃ BO ₃ 27g was mixed and mixed for 10 hours, and then the mixed powder was vitrified at 1450 ° C for 5 hours and rapidly cooled. Made into powder. Next, 120 g of the glass powder and 80 g of alumina were mixed, pulverized, dried, and then, 2 wt% of a polyvinyl alcohol 10% aqueous solution was added to the dried powder as a binder and press-molded at a pressure of 1000 kg / cm 2 for 5 hours at 900-1000 ° C. Calcined for In this way, the overall characteristics of the fired specimen were measured. The measurement conditions of the specimen were as follows.

Volume resistivity (ρ): (D.C 250V) ASTM D257-78

Permittivity (ε): (1MHz) ASTM D150-81

Dielectric Loss (tanδ): (1MHz) ASTM D150-81

Sectional Strength: ASTM E855-84 (3-Bending)

Thermal Expansion Coefficient: (25-500 ℃) ASTM D696-79

The characteristic values of the specimens thus measured are shown in Examples 1 to 10 in Table 1 below.

Example 2

66 g of CaCO ₃ , 138 g of SiO ₂ , 28 g of Al ₂ O ₃ , 21 g of ZnO, 30 g of BaCO ₃ , and 45 g of H ₃ BO ₃ were mixed and mixed, and then vitrified at 1450 ° C. for 5 hours to form a powder.

120 g of this glass powder and 80 g of alumina powder were mixed for 24 hours by a ball mill under the addition of 120 g of a solvent in which trichloroethylene and tetrachloroethylene were mixed 3: 2 and 3.6 g of span85 (trade name: Co., Ltd.) as a peptizing agent. It became. The first mixed sheet was subjected to secondary ball milling for another 24 hours under the addition of 12 g of polyvinyl butyral resin as a binder and 18 g of dibutyl phthalic acid as a plasticizer. The viscosity of the mixed sheets in this way was 800 cps, but after the degassing step, the viscosity was adjusted to 18,000-20,000 cps, and a sheet of 1.5-2 mm was obtained by using a doctor blade device. The sheet was cut to a size of 2.5 × 2.5 cm and calcined at 900-1000 ° C., and then measured for each property. Examples 11 and 12 in Table 1 were specimens prepared in this manner.

TABLE 1

Claims (1)

CaO 5-28wt%, Al ₂ O ₃ 0-15wt%, BaO 5-15wt%, SiO ₂ 40-50wt%, ZnO 5-10wt%, B ₂ O ₃ 2-25wt% and less than 10wt% of unavoidable metal oxide Low temperature firing ceramics, characterized in that the magnetic composition having a composition of 55-75wt% of glass powder and 45-25wt% of Al ₂ O ₃ powder.