JPH0280346A - Composite for substrate to be calcined at low temperature and low-temperature calcined substrate - Google Patents

Abstract

PURPOSE:To prevent the outflow of low-melting-point glass and to obviate a decrease in the solder wettability by incorporating a specified amt. of a material forming a lead compd. by a reaction with lead in calcination into the composition for a substrate to be calcined at low-temp. consisting essentially of a lead-contg. low-melting-point glass frit and a refractory filler. CONSTITUTION:(A) A lead-contg. low-melting-point glass frit (e.g., PbO-Al2 O3-SiO2-CaO based glass frit), (B) a refractory filler (e.g., alumina), (C) 0.01-30wt.%, based on the total amt. of the components A and B, of a material (e.g., Nb2O5 and Ta2O5) forming a lead compd. by a reaction with lead in calcination, and (D) a necessary additive such as an org. binder, a plasticizer, and a solvent are mixed to produce the composition for a substrate to be calcined at low. temp. As a result, the component (C) reacts with the PbO in the component A in calcination to form PbNb2O5, etc., hence the softening point of the component A is elevated, an excessive increase in the fluidity of the component A in calcination is prevented, and the outflow of glass can be obviated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a composition for low-temperature firing substrates and the like.

[Conventional technology] Low-temperature fired substrates that are fired at 1000°C or less using low-melting point glass frit, etc. or inorganic refractory fillers such as alumina, when multilayered, are made of low-melting point, low-resistance conductors such as Cu and Ag. It is suitable for high-frequency circuits and is attracting attention because it can be used with

However, in order to enable sintering at a low temperature of 1000°C or lower, the low-temperature firing substrate is composed of a high-melting point inorganic refractory filler and a low-melting glass frit that softens at 500 to 800°C. .

Therefore, at a firing temperature of, for example, 900°C, the softened low-melting glass increases its fluidity and flows out onto the surface of the substrate, which has the disadvantage that it covers the surface of the conductor formed on the surface of the substrate and deteriorates the solder wettability. Ta.

Furthermore, in order to prevent the low melting point glass from flowing out onto the surface of the substrate, if a glass whose softening point is close to the firing temperature of the substrate is used, for example, glass with a glass softening point of 900°C is fired at 900°C. In some cases, the fluidity of the glass is insufficient and the substrate cannot be sintered densely, resulting in a weak strength.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned drawbacks of the prior art, and to create a new composition for low-temperature firing substrates that was previously unknown. The purpose is to provide

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and in a composition for a low-temperature fired substrate whose inorganic components are a lead-containing low-melting glass frit and a refractory filler, The object of the present invention is to provide a composition for a low-temperature fired substrate, in which a substance that reacts with lead to form a lead compound during firing is added in an amount of 0.01 to 30% by weight based on the above inorganic components.

The present invention will be explained in detail below. Note that % means weight % unless otherwise specified.

The present invention provides a low melting point glass frit containing lead (pb),
In a composition for a low-temperature fired substrate comprising a refractory filler or the like, NbJs is contained in the composition.

By containing a substance that forms a lead compound such as Ta21s, the lead compound is formed with PB contained in the low melting point glass frit in the low temperature fired substrate composition during firing at 1000"C or less. This is intended to prevent the elution of the low melting point glass onto the surface of the substrate by causing the substances to react and forming a lead compound.Note that PB is usually contained in the low melting point glass frit as a lead oxide. There is.

The substances forming the lead compound may be used alone or in combination of two types.

The amount of the substance forming the lead compound added is preferably 0.01 to 30% based on the total amount of the low melting point glass frit and the refractory filler, which is the inorganic component.

If the amount added is less than 0.01%, the effect of improving solder wetting will be small (on the other hand, if it exceeds 30%, the dielectric constant of the low-temperature fired substrate will increase, which is undesirable. The desirable range is 0.01%.
05 to 20%, and a particularly desirable range is 0.1 to 1O
%.

On the other hand, the amount of lead-containing glass frit according to the present invention is not particularly limited, but if the amount of glass frit in the inorganic component is less than 30%, a dense sintered layer cannot be formed;
% or more is not preferable because the solder wettability of the conductor on the board decreases.

The amount of lead-containing glass frit is particularly preferably 40 to 60%.

As the refractory filler, alumina (A1.O,), zircon, cordierite, forsterite, etc. can be used alone or in combination. All of these fillers have the characteristics of being compatible with glass, producing a dense sintered substrate, and being easy to obtain.

[Function] In the present invention, Nb2O5 and TaaOs, which are substances forming the lead compound according to the present invention, react with pbo contained in the low melting point glass frit in the composition for a low temperature fired substrate, and form PbNb1Os, PbTa*Os. By forming this, it functions to raise the softening point of the above-mentioned low melting point glass. Therefore, the fluidity of the low melting point glass is prevented from increasing excessively during firing, and the low melting point glass is prevented from flowing out onto the surface of the low temperature fired substrate. Therefore, the phenomenon in which the low melting point glass flowing out onto the surface of the low-temperature fired substrate covers the conductor surface and inhibits solder wettability is prevented.

[Example] NbzOs, TazOs [
Next, an acrylic resin as an organic binder, dibutyl phthalate as a plasticizer, and toluene as a solvent were added to these and kneaded to prepare a slurry having a viscosity of 10,000 to 30,000 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. Print conductor paste on this green sheet and
The layers were laminated, thermocompressed at 90° C., 10 kg/am” for 6 minutes, and fired at 900° C. for 6 hours to obtain a multilayer low temperature fired substrate.

The firing atmosphere was air when the Ag-Pd conductor was printed, and nitrogen when the copper conductor was printed.

Regarding this multilayer low temperature fired substrate, the sintered density, porosity,
The solder wettability and dielectric constant were evaluated. The conductor materials and evaluation results are shown in Examples in [Table 1] and Comparative Examples in Table 1 and Table 2].

[Characteristics evaluation method] Dielectric constant: 100kHz by Ando Electric AC bridge
The characteristics of z were measured and evaluated.

Temperature 25±1℃, humidity 45±1% Evaluate the wet area ratio of solder Ta.

The area ratio was evaluated.

Continuation of [Table-1] Example [Table-1] Continuation of Example [Table-1] Example [Table-2] Comparative example [Effect of the invention] Formation of lead compounds such as Nb2O5, Taxes, etc. according to the present invention The substance prevents the outflow of low-melting point glass from the surface of the low-temperature fired substrate and provides a new low-temperature fired substrate composition and low-temperature fired substrate that exhibits excellent solder wettability.
Its industrial value is enormous.

Claims (2)

[Claims] (1) In a low-temperature firing substrate composition in which the inorganic component is a lead-containing low-melting glass frit and a refractory filler, the amount of a substance that reacts with lead to form a lead compound during firing is 0.01 to 0.01 to the above inorganic component. A composition for low-temperature firing substrates containing 30% by weight. (2) A low-temperature-fired substrate obtained by firing the composition for a low-temperature-fired substrate according to item 1.