JP3909366B2 - Low dielectric constant porcelain composition and method for producing substrate for electronic circuit using the porcelain composition - Google Patents

Description

【００２９】
【表２】

【００３０】
表２の結果からわかるように、各酸化物成分の含有量が本発明にて定める範囲内である試番1〜20では、焼成温度すなわち焼結可能温度が、Ａｇ導体の適用可能限界である950℃またはそれ以下であり、当初目標とした比誘電率ε_ｒが10以下で、Ｑｆ値が3500以上、共振周波数の温度係数τ_ｆが−30〜＋30ppm／℃のものが得られている。
【００３１】
これに対し、組成が本発明で規定した範囲を外れると、上述の特性のすべてを満足する磁器組成物が得られない。例えば、Ｌｉ_２Ｏが規定範囲より低い試番36ではｆＱ値が高くτ_ｆが小さいすぐれたものが得られるが、その特性を得るための必要焼成温度は980℃と高く、Ａｇの導体使用には不適当である。Ｂｉ_２Ｏ_３を規定範囲より多く含む試番29では860℃で焼結でき、比誘電率ε_ｒが低く温度係数τ_ｆは小さいが、ｆＱ値が低く損失が大きい。また、試番38では低い比誘電率で高いｆＱ値が低い焼成温度で得られているが、ＴｉＯ_２の量が規定範囲を下回っており、温度係数τ_ｆが大きな値を示している。
【００３２】
なお、試番32および34は、Ｑ値が低すぎ、両端短絡形誘電体共振器法では、これらの特性が測定できなかった。
【００３３】
このように、本発明の低誘電率磁器組成物は、比誘電率が低く高周波帯域における損失が低く、温度依存性が小さいものであり、しかも低い焼成温度でその特性を得ることができる。
【００３４】
【発明の効果】
本発明の低誘電率磁器組成物は、比誘電率が低く高周波帯域における損失が低く、温度依存性が小さいものであり、しかも低い焼成温度でその特性を得ることができる。したがって、内部導体や電極として比抵抗の低いＡｇを使用することができ、すぐれた高周波性能と相俟って、電子回路の高周波化、小型化、高密度化のための基板用等の用途に好適である。[0001]
[Technical field to which the invention belongs]
The present invention relates to a dielectric porcelain composition suitable for an electronic component or module used in a high frequency region of several GHz to several tens of GHz, and a method for manufacturing an electronic circuit board using the porcelain composition .
[0002]
[Prior art]
In recent years, with the development of high-speed mass communication and mobile communication of information, in the integrated circuit on the substrate, not only miniaturization and high density, but also the signal to be handled has a frequency of several GHz or more. Utilization has been studied, and a material suitable for such a high frequency band is also demanded for a dielectric ceramic composition used for a substrate. The performance required for this porcelain composition is that the relative permittivity is low in the high frequency band, the dielectric loss tan δ is small, that is, the Q value is high.
[0003]
In general, the lower the relative permittivity, the faster the signal propagation speed in the dielectric, so it is desirable that the relative permittivity ε _r be low for high frequency band applications. The smaller the loss in signal transmission, the better. The Q value should be as high as possible. In addition, the function as a dielectric is used for, for example, a filter or a resonator. In this case, the absolute value of the temperature coefficient τ _f of the resonance frequency is as small as possible in order to perform a stable operation against a temperature change. That is, it is important that the temperature dependency is small.
[0004]
Conductive materials used as internal conductors and internal electrodes on the mounting substrate may be required to be thinned due to miniaturization and high density, so the higher the specific resistance value, the more the loss increases and the cause of heat generation Therefore, it is desirable that the resistance is as low as possible. Such a low resistance material is Ag, Cu, Au, or the like, but these metals all have a melting point as low as about 1000 ° C.
[0005]
An integrated circuit using a porcelain composition as a substrate prints a circuit pattern using a paste-like conductor material on a green sheet, and laminates these sheets and fires them together so that the conductive material and the porcelain composition are simultaneously formed. Sintered and formed. However, when the firing temperature is close to the melting point of the conductor metal or higher than the melting point, diffusion and fluidization occur, and in particular, in the case of Ag, the conductor may become thin or disappear. For this reason, the porcelain composition must be capable of being sintered at a firing temperature of 1000 ° C. or less.
[0006]
As such a porcelain composition that can be fired at a low temperature, there is a so-called glass ceramic. This is a mixture of ceramic aggregates in glass, which makes it possible to sinter at low temperatures by softening the glass, and various improvements have been made by combining aggregates and glass. For example, in the invention disclosed in Japanese Patent Laid-Open No. 10-297960, zinc orthosilicate (Zn ₂ SiO ₄ ) and cristobalite (SiO ₂ ) are used as aggregates, and SiO ₂ —Li ₂ O—ZnO is used as glass. It is said that ceramics with low loss and low dielectric constant can be obtained at 800-1000 ° C.
[0007]
However, since glass ceramics have a large glass composition, the dielectric constant is generally low but the Q value is also low. Therefore, the loss in the high frequency band is large, and the temperature coefficient τ _{f of the} resonance frequency is large. Performance degradation becomes a problem. In many cases, the glass composition and the ceramic composition are prepared separately and mixed to obtain a green sheet, which makes the manufacturing process complicated.
[0008]
[Problems to be solved by the invention]
An object of the present invention is a low dielectric constant ceramic composition that can be sintered at low temperature, has a low relative dielectric constant, has a low loss in a high frequency band, and has a low temperature dependency, and a substrate for an electronic circuit using the ceramic composition To provide a manufacturing method.
[0009]
[Means for Solving the Problems]
The present inventors have made various studies to improve the performance of a porcelain composition used as an electronic circuit substrate in a high frequency band of 2 GHz or higher. Here, the relative permittivity ε _r , the dielectric loss tan δ, and the temperature coefficient τ _f were all measured by using a both-end short-circuited dielectric resonator method (Hack-Coleman method). The target performance at that time is that the relative dielectric constant ε _r is as low as 10 or less, the product of Q (reciprocal of dielectric loss tangent tan δ) and frequency f ( _{expressed in} GHz) is 3500 or more, and the temperature coefficient of the resonance frequency is The firing temperature for substrate production, that is, the sinterable temperature, was 950 ° C. or lower, which is the applicable limit of Ag conductors.
[0010]
Since the Q value has frequency dependency and tends to decrease as the frequency increases, the fQ value (the value of the product of f and Q), which is assumed to show a substantially constant value depending on the material, is superior or inferior in loss. Decided to compare. As a result of comparing and examining the performance of various porcelain compositions, it was determined that the material having an fQ value of 3500 or more was determined to be superior to conventional materials. The temperature dependence of the resonance frequency is measured as a temperature coefficient τ _f of the resonance frequency by the double-end short-circuited dielectric resonator method. This τ _f is −30 to +30 ppm / ° C., that is, its absolute value is 30 ppm / ° C. If it is smaller, it is considered that it is improved over conventional materials.
[0011]
In order to use Ag, which is the material having the lowest specific resistance near room temperature, as the conductor, the firing temperature of the porcelain composition should be below the melting point of Ag of 960.5 ° C., considering diffusion and reaction with the porcelain composition. It is necessary to make the sintered body sufficiently strong at 950 ° C. or less.
[0012]
Glass or glass-ceramics can be sintered at such a low temperature. However, as described above, since the Q value is small, the loss is large and the temperature dependence is large. We examined the possibility of realizing this. First, it was considered that SiO ₂ and ZnO as components constituting ceramics are indispensable for obtaining a high-frequency porcelain composition having a low relative dielectric constant and a high Q value. Therefore, these two components were used as main compositions, and the reduction of the sintering temperature due to the inclusion of various components was examined.
[0013]
As a result, it has been found that the combined addition of four components of Bi ₂ O ₃ , K ₂ O, CuO and Li ₂ O is extremely effective for lowering the sintering temperature. Each of these components is effective in lowering the sintering temperature, but it alone needs to be contained in a large amount, so that the Q value is greatly lowered. On the other hand, when added in combination, the effect of each component is not necessarily clear, but the decrease in the Q value can be reduced and the sintering temperature can be greatly reduced.
[0014]
When TiO ₂ and MgO are further contained in the composition thus obtained, the temperature coefficient τ _f of the resonance frequency can be reduced by reducing the decrease in the Q value and the increase in the relative dielectric constant. did it. When TiO ₂ is contained, τ _f becomes small. However, the relative dielectric constant increases with this, and in addition, the Q value significantly decreases. On the other hand, it has been found that when MgO is contained together, τ _f can be reduced without a significant decrease in the Q value. No effect of reducing the tau _f in the addition of MgO only, Q value was only slightly improved. Such an effect can be obtained by adding it together with TiO ₂ , but the reason is not clear.
[0015]
Based on the above examination results, the present invention was completed by confirming the limit of effectively exhibiting the effect of each component. The gist of the present invention is as follows.
(1) in mass% as the oxide composition _{ratio, SiO 2: 18.0~40.0%, ZnO} : 30.0~54.0%, Bi 2 O 3: 1.0~6.0%, MgO: 1.0~6.0%, TiO 2: 4.0~12.4 %, Li ₂ O: 0.2 to 1.1%, K ₂ O: 3.0 to 7.4%, and CuO: 0.5 to 3.7%.
(2) Each oxide powder raw material is blended in a required amount and wet-mixed in a ball mill, dried, calcined at 700 to 900 ° C., pulverized and sized, then added with a binder, kneaded and molded, After conducting printing and laminating of the conductor, it is sintered at 800 to 950 ° C. , and the oxide composition ratio is mass%, SiO ₂ : 18.0 to 40.0 %, ZnO: 30.0 to 54.0 %, _{Bi 2 O 3: 1.0 ~ 6.0} %, MgO: 1.0 ~ 6.0%, TiO 2: 4.0 ~ 12.4%, Li 2 O: 0.2 ~ 1.1%, K 2 O: 3.0 ~ 7.4% and CuO: the 0.5 to 3.7% The manufacturing method of the board | substrate for electronic circuits using the porcelain composition containing .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The component composition range of the low dielectric constant ceramic composition of the present invention is limited as follows. Here, the content composition is mass% expressed in the form of an oxide.
[0017]
The content range of SiO ₂ is 18.0 to 40.0%. This is because the Q value in the high-frequency region decreases even if the content is less than 18.0% or exceeds 40.0%. Desirable is 19.4 to 39.7%.
[0018]
ZnO is 30.0 to 54.0%. By incorporating it together with SiO ₂ , the basic characteristics of the porcelain composition such as strength, density, insulation and thermal conductivity are realized. When the content is less than 30.0%, sintering is insufficient at a firing temperature of 950 ° C. or lower, resulting in a dense porcelain composition and insufficient mechanical strength. When the content exceeds 54.0%, the Q value decreases. Desirable is 32.1 to 50.8%.
[0019]
Bi ₂ O ₃ contains 1.0 to 6.0%, K ₂ O contains 3.0 to 7.4%, Li ₂ O contains 0.2 to 1.1%, and CuO contains 0.5 to 3.7%. By using a composition containing these components at the same time, it can be sintered into a ceramic composition having a dense and sufficiently strong firing temperature of 950 ° C. or lower. If each component is less than the above lower limit, the effect of lowering the sintering temperature is not sufficient, and a dense porcelain composition cannot be obtained. However, if both are included exceeding the above upper limit value, the Q value decreases and the loss increases. More preferable content range is, _Bi 2 _{O 3} is 1.2 to 5.0%, respectively, _{K 2} O is 3.0 to 7.0% Li ₂ O 0.2 to 1.0%, and CuO is from 1.0 to 3.3%.
[0020]
TiO ₂ is contained in an amount of 4.0 to 12.4%, and MgO is contained in an amount of 1.0 to 6.0%. TiO ₂ is contained in order to reduce the temperature coefficient of the resonance frequency, but 4.0% or more is necessary to obtain this effect. However, since the relative permittivity increases and the Q value decreases, the content of TiO ₂ must be 12.4% or less. MgO has an action of suppressing the increase of the relative dielectric constant and the decrease of the Q value due to the inclusion of TiO _{2, and is} contained at least 1.0% in order to obtain the effect. However, MgO deteriorates the sinterability, so it is at most 6.0%. Preferred range of content TiO ₂ is 4.4 to 11.8%, MgO is 1.1 to 5.5%.
[0021]
The components other than the above are various impurities mixed into the raw material, but are not particularly limited as long as they do not adversely affect the characteristics of the porcelain composition.
[0022]
The production of the porcelain composition may be carried out in accordance with a method for sintering ordinary ceramics, but a required amount of each oxide powder of each component as a raw material is prepared and sufficiently mixed in a ball mill. When the oxide powder is a hygroscopic unstable material such as K ₂ O, other forms such as carbonate may be used, and in that case, the oxide powder has a molar amount corresponding to the oxide amount after sintering. Blend powder. After mixing, the mixture is calcined, and after confirming that the ceramic formation reaction has been performed, pulverization and sizing. The calcination is desirably performed at a low temperature in order to be sufficiently sintered in the final calcination, but if it is too low, a ceramic formation reaction does not occur.
[0023]
A binder or the like is added to the sized powder, kneaded and molded, and if necessary, the conductive circuit is printed, laminated, processed into a final shape, etc., and fired at 800 to 950 ° C. to obtain a porcelain composition. When the firing temperature is less than 800 ° C., sintering is not sufficiently performed, and the mechanical strength may not be obtained due to lack of denseness. When Ag is used for the inner conductor, the conductor may be lost or diffused, so the firing temperature should be up to 950 ° C. In addition, when using Cu for an internal conductor, you may bake over 950 degreeC, However, In order to suppress the oxidation of Cu, it is necessary to set it as inert atmospheres, such as nitrogen atmosphere which does not contain oxygen. In that case, it is preferable to set the temperature up to 1000 ° C. because there is a possibility that seizure with a holding table or the like may occur.
[0024]
【Example】
A porcelain composition having a composition of Table 1 composed of powder materials of high purity SiO ₂ , ZnO, Bi ₂ O ₃ , MgO, TiO ₂ , K ₂ O (as K ₂ CO ₃ ) and CuO having a purity of 95% or more Was made.
[0025]
The raw material powder blended in a predetermined composition was added with pure water using a ball mill made of zirconia balls, wet-mixed for 24 hours, dried and stirred with a laika machine, and calcined at about 750 ° C. for 2 hours. After calcination, it was confirmed by X-ray diffraction that a sintering reaction was performed, and further, pure water was added in a ball mill made of zirconia balls and pulverized for 24 hours to obtain powder having a particle diameter of 1 to 4 μm. After drying, add a binder of 10% PVA aqueous solution, granulate it, mold it into a cylindrical shape with a diameter of 15mm and a height of 8mm at a pressure of 1t / cm ² using a mold, and then fire it in the air to make a specimen. Produced.
[0026]
In that case, each sample is preliminarily baked experimentally at a temperature of 840 to 980 ° C. using a part of the sample, and a temperature necessary for sufficient densification is found. The piece was fired. Both firing times are 2 hours.
[0027]
The sintered body after firing was smoothed by polishing the bottom surface, and then the relative permittivity ε _r and the dielectric loss tan δ (or Q = 1 / tan δ) were determined by a double-end short-circuited dielectric resonator method. Since the dielectric loss varies depending on the measurement resonance frequency f, the magnitude of the loss was evaluated by the fQ value of the product of f and Q, which is assumed to be a constant value in the measured material without being influenced by the frequency. The temperature coefficient τ _f of the resonance frequency was obtained from the rate of change with the resonance frequency f ₀ at 25 ° C. as a reference by measuring the resonance frequency in the temperature range from −25 ° C. to 85 ° C. These measurement results are shown together in Table 2.
[0028]
[Table 1]

[0029]
[Table 2]

[0030]
As can be seen from the results in Table 2, in trial numbers 1 to 20 in which the content of each oxide component is within the range defined in the present invention, the firing temperature, that is, the sinterable temperature is the applicable limit of the Ag conductor. 950 ° C. or lower, an initial target dielectric constant ε _r of 10 or less, a Qf value of 3500 or more, and a resonance frequency temperature coefficient τ _f of −30 to +30 ppm / ° C. are obtained.
[0031]
On the other hand, if the composition is out of the range defined in the present invention, a porcelain composition satisfying all of the above characteristics cannot be obtained. For example, sample No. 36 with a Li ₂ O lower than the specified range can provide an excellent one with a high fQ value and a small τ _f, but the necessary firing temperature for obtaining the characteristics is as high as 980 ° C. Is inappropriate. Sample 29 containing more Bi ₂ O ₃ than the specified range can be sintered at 860 ° C., has a low dielectric constant ε _{r and a} small temperature coefficient τ _f , but has a low fQ value and a large loss. Further, in the trial number 38, a high fQ value with a low relative dielectric constant is obtained at a low firing temperature, but the amount of TiO ₂ is below the specified range, and the temperature coefficient τ _f shows a large value.
[0032]
In the trial numbers 32 and 34, the Q value was too low, and these characteristics could not be measured by the both-end short-circuited dielectric resonator method.
[0033]
As described above, the low dielectric constant ceramic composition of the present invention has a low relative dielectric constant, a low loss in a high frequency band, a small temperature dependency, and can obtain the characteristics at a low firing temperature.
[0034]
【The invention's effect】
The low dielectric constant ceramic composition of the present invention has a low relative dielectric constant, a low loss in a high frequency band, a small temperature dependency, and its characteristics can be obtained at a low firing temperature. Therefore, Ag having a low specific resistance can be used as an internal conductor or electrode, and combined with excellent high frequency performance, it can be used for applications such as substrates for higher frequency, smaller size, and higher density of electronic circuits. Is preferred.

Claims (2)

In mass% as the oxide composition _{ratio, SiO 2: 18.0~40.0%, ZnO} : 30.0~54.0%, Bi 2 O 3: 1.0~6.0%, MgO: 1.0~6.0%, TiO 2: 4.0~12.4%, Li A low dielectric constant ceramic composition comprising ₂ O: 0.2 to 1.1%, K ₂ O: 3.0 to 7.4%, and CuO: 0.5 to 3.7%. The required amount of powder raw materials for each oxide is mixed and wet mixed in a ball mill, dried, calcined at 700 to 900 ° C., pulverized and sized, then added with a binder, kneaded and molded, After printing and laminating, it is sintered at 800 to 950 ° C. , and the oxide composition ratio is mass%, SiO ₂ : 18.0 to 40.0 %, ZnO: 30.0 to 54.0 %, Bi ₂ O _{3: 1.0 ~ 6.0%, MgO} : 1.0 ~ 6.0%, TiO 2: 4.0 ~ 12.4%, Li 2 O: 0.2 ~ 1.1%, K 2 O: 3.0 ~ 7.4% and CuO: porcelain containing 0.5 to 3.7% The manufacturing method of the board | substrate for electronic circuits using a composition.