JP2004075534A - Insulating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulating composition stable to an internal wiring material for low temperature baking and provided with necessary characteristics. <P>SOLUTION: The insulating composition comprises an inorganic filler and a glass frit composed mainly of metal oxides selected from the group consisting of CaO, ThO<SB>2</SB>, BeO, SrO, MgO, Y<SB>2</SB>O<SB>3</SB>, rare earth oxides, Sc<SB>2</SB>O<SB>3</SB>, BaO, HfO<SB>2</SB>, ZrO<SB>2</SB>, Al<SB>2</SB>O<SB>3</SB>, Li<SB>2</SB>O, TiO, CeO<SB>2</SB>, SiO<SB>2</SB>, B<SB>2</SB>O<SB>3</SB>, Ta<SB>2</SB>O<SB>5</SB>, Cr<SB>2</SB>O<SB>3</SB>, and ZnO. The acidity/basicity of the glass frit is ≥0.503. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an insulating composition containing an inorganic material filler and glass frit and suitable for a circuit board or the like.

セ ラ ミ ッ ク As a circuit board used for a hybrid integrated circuit of an electronic device, a ceramic substrate containing alumina as a main component is used in terms of electrical insulation, mechanical strength, heat conductivity, and the like. However, a ceramic substrate containing alumina as a main component has a large relative dielectric constant of about 9, and is not suitable for an electronic circuit having a high signal propagation speed. In addition, since a ceramic material containing alumina as a main component must be fired at a high temperature of about 1400 to 1650 ° C., when providing internal wiring inside the substrate, a high melting point metal such as tungsten or molybdenum is used as the internal wiring material. Must be used. In this case, since the specific resistance of the refractory metal is high, an electronic circuit having a high signal propagation speed cannot be formed.

Therefore, for example, Japanese Patent Application Laid-Open No. 61-108192 discloses a composition for a circuit board for low-temperature firing, in which a ceramic inorganic filler such as alumina is added to a glass frit. According to the composition for a circuit board, since an internal wiring material having a low relative permittivity and a low melting point and a low specific resistance of a gold, silver, or copper can be used, an electronic circuit having a high signal propagation speed is used. Can be realized.

When a circuit board (for example, a multilayer circuit board) having internal wiring made of a conductive material such as gold, silver, or copper is manufactured using the conventional composition for a circuit board, the conductive material becomes In some cases or in the interface with the substrate (for example, see Japanese Patent Publication No. 47-13673). It is considered that this is because a weak bond is generated between the conductive material and oxygen of the metal oxide constituting the glass frit during firing, and the silver is apparently oxidized. When the above phenomenon occurs, for example, the substrate changes color from white to light yellow, and electrical characteristics such as dielectric loss tangent deteriorate.

の An object of the present invention is to provide an insulating composition which is stable with respect to an internal wiring material for low-temperature firing and can realize a circuit board having necessary characteristics.

Insulating compositions of the present invention, and an inorganic material _{filler, CaO, ThO 2, BeO,} SrO, MgO, Y 2 O 3, rare earth _{oxides, Sc 2 O 3, BaO,} HfO 2, ZrO 2, Al 2 O ₃ , glass frit containing as a main component a metal oxide selected from the group consisting of Li ₂ O, TiO, CeO ₂ , SiO ₂ , B ₂ O ₃ , Ta ₂ O ₅ , Cr ₂ O ₃ and ZnO. In the insulating composition, the acid-base degree of the glass frit is 0.503 or more (however, the acid-base degree (pO) of the glass frit containing i kinds of metal oxides is determined by the metal oxide When the oxidation number of the metal component i contained in the product is Zi, the atomic ratio of the component i when the oxygen atom in the component i is 1 g atom is ei, and the basicity of the component i is Gi,

で規定され、
　更に、ＧｉはＬ．Ｇ．ポーリングで電気陰性度Ｘｉを用いて、

Defined by
Further, Gi is based on L. G. FIG. Using electronegativity Xi in polling,

で規定されるものとする）。

).

The inorganic material filler used in the present invention is, for example, a component for improving the strength of a circuit board formed from the insulating composition. Examples of the inorganic filler include cristobalite, quartz, corundum (α-alumina), mullite, stabilized zirconia, steatite, forsterite, cordierite, spinel, and zircon. These inorganic material fillers may be used as a mixture of two or more kinds. As the inorganic material filler, quartz, corundum, and cordierite are particularly preferable. By using these inorganic fillers, a circuit board having good strength can be realized. In addition, since the thermal expansion coefficient of the substrate is reduced and approaches the thermal expansion coefficient of silicon (around 40 × 10 ⁻⁷ / ° C.), when a silicon chip electronic component such as an IC is arranged on the substrate, thermal shock occurs. , The good connection between the electronic component and the circuit board is maintained. When corundum is used as the inorganic filler, a circuit board with high cost performance can be realized in addition to the effects described above.

粒径 The particle diameter of the inorganic material filler is not particularly limited, but usually has an average particle diameter of 1.0 to 6.0 µm, preferably 1.5 to 4.0 µm. When the average particle size is less than 1.0 μm, it becomes difficult to slurry the composition of the present invention. Conversely, if the average particle size exceeds 6.0 μm, it is difficult to obtain a dense substrate.

ガ ラ ス The glass frit used in the present invention is a glass frit containing a plurality of metal oxide components. In particular, a glass frit having an acid-base degree of at least 0.503, preferably at least 0.506, more preferably at least 0.508. This is because, in a glass frit having a small acid-base degree, oxygen in a metal oxide is easily extracted, and thus it is considered that another metal atom is easily taken in by, for example, ion exchange. In other words, it is considered that the internal wiring material is likely to diffuse into the substrate during firing.

The acid-base degree referred to in the present invention is described in J. Org. A. Duffy and M.S. D. This is defined in Ingram's dissertation (GLASS SCIENCE AND TECHNOLOGY, 7 , 8). The acid-base degree (pO) of a glass frit containing i kinds of metal oxides is defined by the above-described equation (Equation 1).

中 In the formula, Zi is the oxidation number of the metal component contained in each metal oxide, ei is the atomic ratio of component i when the oxygen atom in component i is 1 g atom, and Gi is the basicity of component i. Here, Gi is L. G. FIG. Since the above equation (Equation 2) can be obtained using the polling electronegativity Xi, the equation (Equation 1) can be rewritten as the following equation (Equation 3).

　本発明で用いられる、酸塩基度が０．５０３以上のガラスフリットとしては、前述したように、ＣａＯ、ＴｈＯ₂、ＢｅＯ、ＳｒＯ、ＭｇＯ、Ｙ₂Ｏ₃、希土類酸化物、Ｓｃ₂Ｏ₃、ＢａＯ、ＨｆＯ₂、ＺｒＯ₂、Ａｌ₂Ｏ₃、Ｌｉ₂Ｏ、ＴｉＯ、ＣｅＯ₂、ＳｉＯ₂、Ｂ₂Ｏ₃、Ｔａ₂Ｏ₅、Ｃｒ₂Ｏ₃及びＺｎＯからなる群から選ばれた金属酸化物を主成分とするものが好ましく、このようなガラスフリットは、主成分である金属酸化物が高温時のギブスの生成自由エネルギーが小さな非還元性酸化物であるため、非酸化性雰囲気で焼成する際でも還元されない。

As described above, as the glass frit having an acid-base degree of 0.503 or more, CaO, ThO ₂ , BeO, SrO, MgO, Y ₂ O ₃ , rare earth oxide, Sc ₂ O ₃ , _{BaO, HfO 2, ZrO 2,} Al 2 O 3, Li 2 O, TiO, CeO 2, SiO 2, B 2 O 3, Ta 2 O 5, Cr 2 O 3 and a metal oxide selected from the group consisting of ZnO It is preferable that the glass frit is fired in a non-oxidizing atmosphere because the metal oxide as the main component is a non-reducing oxide having a small free energy of Gibbs generation at a high temperature. It is not reduced even when you do.

As an example of a glass frit containing a non-reducing oxide as a main component as described above, 18.0 mol% of Al ₂ O ₃ , 50.0 mol% of SiO ₂ , and 5.0 mol% of B ₂ O ₃ , ZnO at 9.0 mol% and MgO at 18.0 mol%. In this glass frit, Xi, Zi and ei of each component are as shown in Table 1 below.

　表１のデータに基づいて、式（数３）によりｐＯ値を求めると、０．５０６７となる。ここで、上述のガラスフリットを例にして、ｅｉ値の求め方を説明する。まず、ガラスフリット中の全酸素の原子量を計算する。これは、成分ごとに酸素量を求め、これを加えると求められる。成分ごとの酸素量は、当該成分のガラスフリット中の割合に、（酸素原子のモル数／当該成分に含まれる原子のモル数の総和）を乗じると得られる。たとえば、Ａｌ₂Ｏ₃では、次の式（数４）のようになる。

When the pO value is obtained from the data of Table 1 by the equation (Equation 3), it is 0.5067. Here, a method of obtaining the ei value will be described using the above-described glass frit as an example. First, the atomic weight of total oxygen in the glass frit is calculated. This is determined by determining the amount of oxygen for each component and adding it. The amount of oxygen for each component is obtained by multiplying the ratio of the component in the glass frit by (the total number of moles of oxygen atoms / the number of moles of atoms contained in the component). For example, in Al ₂ O ₃ , the following equation (Equation 4) is obtained.

　これをＳｉＯ₂、Ｂ₂Ｏ₃、ＺｎＯ及びＭｇＯについても計算し、得られた値を加えて全酸素の原子量を求めると、０．６１となる。各成分のｅｉは、得られた全酸素の原子量を１とした場合の非酸素成分（Ａｌ₂Ｏ₃の場合はＡｌ）の原子量を求めると得られる。Ａｌ₂Ｏ₃のｅｉ値は、次の式（数５）から導かれる。

This is also calculated for SiO ₂ , B ₂ O ₃ , ZnO and MgO, and the obtained value is added to obtain the total oxygen atomic weight, which is 0.61. The ei of each component is obtained by calculating the atomic weight of the non-oxygen component (Al in the case of Al ₂ O ₃ ), where the obtained atomic weight of oxygen is 1. The ei value of Al ₂ O ₃ is derived from the following equation (Equation 5).

　また、本発明で用いられるガラスフリットは、焼成後にコージェライト、ムライト、スピネル、アノーサイト、セルジアン、β−スポジュメン、ドロマイト、ベタライト及びその置換誘導体の結晶を少なくとも１種析出する結晶化ガラスフリットであればより好ましい。上述のような結晶を析出する結晶化ガラスフリットを用いると、より強度の高い回路基板が実現できる。また、回路基板に厚膜抵抗体を形成した際に、その厚膜抵抗体の安定性が良好である。特に、アノーサイト又はセルジアンを析出する結晶化ガラスフリットを用いると、より強度の高い回路基板が実現できる。なお、コージェライト、ムライト又はβ−スポジュメンを析出し得る結晶化ガラスフリットは、焼成後の熱膨張率が小さなため、ＩＣ等のシリコンチップ電子部品を配置するための回路基板を構成する上で有効である。

Further, the glass frit used in the present invention is a crystallized glass frit that precipitates at least one crystal of cordierite, mullite, spinel, anorthite, serdian, β-spodumene, dolomite, betalite and a substituted derivative thereof after firing. More preferred. Use of a crystallized glass frit that precipitates crystals as described above can realize a circuit board with higher strength. Further, when the thick film resistor is formed on the circuit board, the stability of the thick film resistor is good. In particular, when a crystallized glass frit that precipitates anorthite or Celsian is used, a circuit board with higher strength can be realized. In addition, the crystallized glass frit capable of depositing cordierite, mullite or β-spodumene has a small coefficient of thermal expansion after firing, and thus is effective in forming a circuit board for arranging silicon chip electronic components such as ICs. It is.

Particularly preferred as the crystallized glass for depositing the above crystals are those containing B ₂ O ₃ and SiO ₂ as a network homer, containing Al ₂ O ₃ as an intermediate, and an alkaline earth metal oxide as a network modifier. (MgO, CaO, SrO, BaO) or a glass frit containing ZnO. Such a glass frit is suitable for firing the composition of the present invention at about 800 to 1050 ° C. because it has a wide range of vitrification and a yield point of about 600 to 800 ° C. Accordingly, there is an advantage that a copper-based, silver-based, or gold-based conductive material having a low specific resistance and a low melting point can be used as the internal wiring. In this glass frit, if CaO, SrO, or BaO is selected as a network modifier, RO—Al ₂ O ₃ .2SiO ₂ (R is an alkaline earth metal) crystal such as anorthite or Celsian is deposited. Can be done. If MgO is selected, cordierite crystals can be obtained, and if ZnO is selected, garenite crystals can be obtained.

ガ ラ ス The glass frit used in the present invention is manufactured by a known method. That is, it can be obtained by mixing predetermined components at a predetermined ratio, heating and melting the mixture, gradually cooling and then pulverizing the mixture. The average particle size of the glass frit is not particularly limited, but is preferably about 1 to 3 μm.

第三 In addition to the above-mentioned inorganic material filler and glass frit, a third component such as an oxidizing agent may be added to the insulating composition of the present invention, if desired.

In the insulating composition of the present invention, the ratio of the above-mentioned inorganic material filler is preferably set to 5 to 70% by weight (more preferably, 20 to 60% by weight). If the content of the inorganic material filler is less than 5% by weight, sufficient strength cannot be obtained when a circuit board is formed. Conversely, if it exceeds 70% by weight, the glass frit does not act as an inorganic binder, and the strength is rather reduced when a circuit board is formed.

Since the insulating composition of the present invention contains a glass frit having an acid-base degree of 0.503 or more, it is stable with respect to the internal wiring material for low-temperature firing, and furthermore, it is necessary to have a dielectric loss tangent or an insulating property. A circuit board having characteristics can be realized.

Further, when a circuit board is formed using the insulating composition of the present invention, since the substrate body is made of the above-described insulating composition, it is stable with respect to the internal wiring and has stable electric characteristics.

FIG. 1 is a vertical cross-sectional partial view of a multilayer circuit board formed using the insulating composition of the present invention. In the figure, a multilayer circuit board 1 mainly includes a multilayer board 2 and internal wirings 3.

The laminated substrate 2 is composed of integrated sheets 2a, 2b, and 2c obtained by laminating three green sheets of the insulating composition and integrally firing them. Each green sheet is composed of the above-described insulating composition according to the present invention.

The internal wiring 3 is formed in a predetermined pattern between the sheets 2a and 2b and between the sheets 2b and 2c. The internal wiring 3 is connected through the through hole 4 and extends to the surface of the multilayer substrate 2 through the through hole 4. The tip of the internal wiring 3 extending to the surface of the laminated substrate 2 forms an electrode 3a on the upper surface and the lower surface of the laminated substrate 2 in the drawing. The internal wiring 3 is formed using a silver-based, gold-based, or copper-based conductive material that can be fired at a low temperature.

In the multilayer circuit board 1, since the laminated board 2 is made of the above-described insulating composition, the internal wiring material is unlikely to be diffused by the action of ion exchange or the like. Therefore, the multilayer circuit board 1 is hardly discolored and has good electric characteristics such as a dielectric loss tangent.

In the multilayer circuit board 1, when a silver-based conductive material is used for the internal wiring 3, the insulating composition includes B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ and a small amount of an alkaline earth metal oxide and / or It is preferable to use a glass frit containing lead oxide. In this case, since the glass has excellent softening fluidity, it can be fired in a short time, and is expected to have an effect of being excellent in acid resistance and corrosion resistance to chemicals. When is used, it is preferable to use an insulating composition containing a glass frit containing the above-mentioned non-reducing oxide as a main component. In this case, since the insulating composition can be fired in a non-oxidizing atmosphere, oxidation of the internal wiring 3 can be prevented.

Next, a method for manufacturing the multilayer circuit board 1 will be described.

First, an insulating composition, an organic binder (for example, polymethacrylate resin), a plasticizer (for example, dibutyl phthalate), a solvent (for example, methyl ethyl ketone), and another additive (for example, an antifoaming agent) are mixed at a predetermined ratio. This is kneaded for about 24 to 72 hours using a ball mill to prepare a homogeneous slurry. After defoaming this slurry, a green sheet having a thickness of about 100 to 300 μm is formed by a known method such as a doctor blade method.

Next, a predetermined internal wiring pattern is formed on the surface of the obtained green sheet. Here, first, through holes for ensuring conduction between the internal wirings are formed in the green sheet. Then, a predetermined internal wiring conductor paste is filled in the through holes, and then a predetermined internal wiring pattern is formed on the surface of the green sheet. The pattern formation is performed by, for example, a screen printing method.

Note that the step of filling the through-holes with the paste may be performed after the formation of the internal wiring pattern.

導体 The conductive paste for internal wiring is obtained by adding an organic vehicle to silver-based, gold-based or copper-based conductive metal powder and kneading the mixture. Preferably, a small amount of glass frit is added to the conductive paste. This is because when the circuit board is fired, the joint strength between the circuit board and the internal wiring can be increased by matching the thermal shrinkage behavior of the insulating composition and the internal wiring material. As the glass frit added to the conductive paste, for example, borosilicate alkaline earth metal salt glass can be exemplified.

(5) Next, green sheets on which predetermined internal wiring patterns are formed are laminated in a predetermined order and subjected to thermocompression bonding or the like to obtain a laminate. Then, the obtained laminate is cut into a predetermined size and fired. The firing of the laminate is preferably performed in two stages. In this case, first, organic substances (organic binders) contained in the green sheet or the like are removed by the first-stage baking. This firing is usually performed at a temperature of about 500 ° C. Next, the second stage baking aims at baking the insulating composition and the internal wiring material. The firing temperature at this time is mainly determined from the melting point of the glass frit or the conductive material for the internal wiring, but is usually 800 to 1050 ° C. The firing atmosphere is appropriately adjusted according to the internal wiring material. For example, when a copper-based internal wiring material is used, firing is performed in a non-oxidizing atmosphere. When the firing is completed, the multilayer circuit board 1 of the present invention is obtained.

The obtained multilayer circuit board 1 is used with a predetermined surface circuit pattern 5 disposed on the surface and a thick film resistor 6 disposed on a predetermined portion of the surface. The surface circuit pattern 5 is formed by arranging and firing a gold-based, silver-based, or copper-based conductive material by an ordinary thick-film printing method. As the conductive material, a copper-based material that hardly causes migration is particularly preferable. As a copper-based material, DuPont thick copper film conductor No. 6001 can be exemplified. When the internal wiring 3 is made of a silver-based material, the firing temperature is preferably set to less than 779 ° C. This is because the eutectic point of copper and silver is 779 ° C., and when baked at a temperature higher than that, a liquid phase occurs at the interface between the surface circuit pattern 5 and the internal wiring 5, resulting in poor connection between the two wirings. Because there is.

The thick film resistor 6 is disposed between the surface circuit patterns 5, between the electrodes 3a, or between the electrodes 3a and the surface circuit patterns 5. The thick film resistor 6 is formed by arranging a paste composed of a conductive material, an inorganic binder, and an organic vehicle at a predetermined position and firing the paste. The conductive material is appropriately selected depending on the firing conditions. For example, when firing in an oxidizing atmosphere, ruthenium oxide is used. When firing in a non-oxidizing atmosphere, metal borides such as lanthanum hexaboride, metal silicides such as tantalum silicide, metals such as tantalum, metal oxide semiconductors such as tin oxide, and oxides such as calcium ruthenate are used. Ruthenium derivatives and the like are used. The paste for forming the thick film resistor 6 is applied so that the film thickness after firing becomes about 10 to 20 μm. A protective layer is formed on the formed thick film resistor 6 as required. This protective layer can be formed by arranging the resistor protective glass by a normal thick film baking method. The resistance of the thick film resistor 6 may be adjusted by a laser trimming method or the like.

(1) Adjustment of Glass Frit The metal oxides shown in Table 2 were mixed at the ratios shown in Tables 3, 4, 5, and 6, and after melting at 1400-1600 ° C., the glass was dropped into water to form a glass. Manufactured. The obtained glass was placed in an alumina pot together with water and alumina balls, wet-pulverized and then dried to produce a glass frit having an average particle size of 2 μm.
(2) Preparation of Insulating Composition Fillers were mixed with the glass frit obtained in (1) in the proportions shown in Tables 3, 4, 5, and 6 to obtain an insulating composition.
(3) Production of circuit board 63.0% by weight of the insulating composition obtained in (2), 6.5% by weight of acrylic resin, 2.5% by weight of dibutyl phthalate and 28.0% by weight of toluene were mixed. The slurry was formed into a slurry, and a green sheet having a thickness of 200 μm was formed from the slurry by a doctor blade method. A silver paste was printed and printed on the green sheet so that the thickness after drying was 20 μm. Then, the green sheet on which the silver paste was printed was fired at 900 ° C. for 30 minutes to obtain a circuit board. In Examples 21, 22, and 23, a copper paste was used instead of the silver paste.

に つ い て About the obtained circuit board, discoloration around the silver film (or copper film) was visually observed, and a dielectric loss tangent was measured as an electrical property. The dielectric loss tangent was measured by a bridge method using a capacitance measuring device (model 4297 manufactured by YHP). The results are shown in Tables 3, 4, 5, and 6.

Since the insulating composition of the present invention contains a glass frit having an acid-base degree of 0.503 or more, it is stable with respect to the internal wiring material for low-temperature firing, and furthermore, it is necessary to have a dielectric loss tangent or an insulating property. A circuit board having characteristics can be realized.

場合 In addition, when a circuit board is formed using the insulating composition of the present invention, the substrate body is made of the above-described insulating composition, so that it is stable with respect to the internal wiring and has stable electric characteristics.

It is a longitudinal section partial view of an example of a circuit board concerning the present invention.

Explanation of reference numerals

Reference Signs List 1 multilayer circuit board 2 laminated board 3 internal wiring

Claims (3)

Inorganic material filler, CaO, ThO ₂ , BeO, SrO, MgO, Y ₂ O ₃ , rare earth oxide, Sc ₂ O ₃ , BaO, HfO ₂ , ZrO ₂ , Al ₂ O ₃ , Li ₂ O, TiO, CeO ₂ , an insulating composition comprising: a glass frit containing a metal oxide selected from the group consisting of SiO ₂ , B ₂ O ₃ , Ta ₂ O ₅ , Cr ₂ O ₃ and ZnO as a main component; An insulating composition characterized by having an acid-base degree of 0.503 or more.
(However, the acid-base degree (pO) of a glass frit containing i kinds of metal oxides is defined assuming that the oxidation number of a metal component i contained in each metal oxide is Zi and the oxygen atom in the component i is 1 g atom. When the atomic ratio of the component i is ei and the basicity of the component i is Gi,

Defined by
Further, Gi is based on L. G. FIG. Using electronegativity Xi in polling,

Defined by The glass frit is a crystallized glass frit that precipitates at least one crystal of cordierite, mullite, spinel, anorthite, Celsian, β-spodumene, dolomite, petalite and a substituted derivative thereof after firing. The insulating composition according to claim 1. The insulating composition according to claim 1, wherein the proportion of the inorganic material filler is 5 to 70% by weight.

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