JPH0643258B2 - Dielectric material for circuit boards - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric material useful as a circuit board, and more particularly to a dielectric material which can be fired at a low temperature and has a high bending strength.

Conventional technology With the high-density mounting of semiconductors and circuit components such as LSI,
In recent years, multilayer circuit boards have been widely adopted. A ceramic multilayer circuit board is manufactured by alternately laminating dielectric layers and conductor layers, co-firing and integrating them, and conventionally, alumina-based ceramics have been mainly used as a dielectric material. It was By the way, alumina is insulating,
It has excellent properties such as mechanical strength, but the sintering temperature is 1500 ℃.
Since high-melting point metals such as _Mo and W having relatively high electric resistance are used for the internal wiring conductor material, the conductor width must be made large, and miniaturization and high density are difficult. . Therefore, Ag, A with low electric resistance and low melting point
In order to use a highly conductive metal such as u or Cu as a conductor material, it is desired to develop a dielectric material that can be sintered at a temperature below the melting point of these metals.

Furthermore, the dielectric constant of the dielectric material has a great effect on the propagation speed of the signal inside the substrate, but the dielectric constant of alumina ceramics is about
Since it is relatively large at 8.5 to 10 and there is a limit to speeding up signal transmission, a dielectric material having a lower dielectric constant is required.

In response to these demands, various dielectric materials such as low temperature sintered ceramics, crystallized glass, and glass-ceramics mixtures have been proposed in recent years, and some of them have been put into practical use.
It does not satisfy all the electrical characteristics such as the permittivity and the mechanical strength required characteristics of the circuit board. In particular, the type of material which is currently put into practical use and which is fired at a low temperature in a non-oxidizing atmosphere has a defect that the bending strength is 2000 kg or less, which is significantly smaller than that of an alumina substrate.

The present inventors previously found that NgO, B ₂ O ₃ , SiO ₂ , BaO,
ZrO ₂ as a constituent component and BaZr (BO ₃ )
We developed a glass material that produced _two crystals and showed excellent insulating and dielectric properties, and filed a patent application. However, although this material exhibits excellent properties, its strength tends to be slightly lower than that of the alumina substrate.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention An object of the present invention is to provide a novel dielectric material for circuit boards, which can be fired at a low temperature, exhibits excellent insulating properties and dielectric properties after firing, and has improved mechanical strength. To do.

Means for Solving the Problems The present invention provides (A) magnesium, boron, silicon, barium,
Zirconium, aluminum and calcium are respectively converted into oxides MgO 20 to 40% by weight, B ₂ O ₃ 10 to 30% by weight, SiO ₂ 10 to 35% by weight, BaO 5 to 22% by weight, ZrO ₂ 5 to 20% by weight. , Al ₂ O ₃ 2 to 15% by weight, CaO 0 to 5% by weight, and the glass of (B) and (A) which have been heat-treated and crystallized in advance. It is a dielectric material for a circuit board, which consists of one or more selected types. The second invention is the glass and / or the glass-
It is a dielectric material for circuit boards in which crystalline filler is added to ceramics.

Glass (A) of the present invention, the raw material compounds of each component oxide is mixed so as to be in the above-mentioned roughening range in terms of oxide, and melted at a temperature of, for example, 1400 to 1600 ° C. according to a usual glass manufacturing method, It is then produced by quenching the melt to glass and crushing it. Also glass-ceramics
(B) is produced by heat-treating this glass at a crystallization temperature or higher to crystallize it in advance and then pulverize it.

As the crystalline filler, oxides such as alumina, zirconia, silica, beryllia, silicon zirconium, staratite, forsterite and mullite, and nitrides such as silicon nitride, aluminum nitride and boron nitride can be used.

Action The glass of the present invention has a crystallization temperature in the vicinity of 800 to 900 ° C., and is partly crystallized into a glass-ceramic by firing at a temperature above the crystallization temperature. As a result of X-ray diffraction analysis, the fired body was mainly BaZr (BO ₃ ) ₂ and BaAl ₂
It consists of two crystal phases of Si ₂ O ₈ and a glassy three phase of the balance composition. Due to the coexistence of these crystal phases and the glass phase, a dense dielectric having a high mechanical strength and an excellent insulating property is obtained. It is thought to be obtained.

That is, the BaZr (BO ₃ ) ₂ crystal becomes a dielectric having a low dielectric constant and excellent insulating properties in coexistence with the above glassy material. On the other hand, Al ₂ O ₃ in the glass component greatly improves the bending strength of the fired body. This is due to Al ₂ O ₃
A new crystalline phase of l ₂ Si ₂ O ₈ (celsian) appears,
It is considered that this contributes to the increase in strength and the increase in the crystallinity of the entire system. Al ₂ O ₃
Although the sintering temperature is increased by blending, the addition of CaO can suppress the increase in the sintering temperature without affecting the production of the two crystal phases.

The reason for limiting the glass composition range is as follows.

When MgO is out of the range of 20 to 40% by weight, the crystals are hard to precipitate. If the content of B ₂ O ₃ exceeds 30% by weight, the strength is lowered and it cannot be used for a circuit board, and if it is less than 10% by weight, melting during glass production becomes difficult. SiO
_{When 2} exceeds 35% by weight, crystallization becomes slow. On the other hand, if the amount is less than 10% by weight, crystallization of the glass is accelerated and the sinterability is deteriorated. When BaO is more than 22% by weight, the dielectric constant becomes high, and when it is less than 5% by weight, ZrO ₂ causes a phase separation, and a homogeneous glass-ceramic cannot be obtained. When ZrO ₂ exceeds 20% by weight, it becomes difficult to melt, and when it is less than 5% by weight, the crystallization reaction becomes slow and only an incomplete crystal phase can be obtained. If Al ₂ O ₃ exceeds 15% by weight, the sintering temperature becomes high, which is not desirable, and if it is less than 2% by weight, the mechanical strength is not efficiently increased. CaO does not necessarily have to be blended, but is effective in suppressing the sintering temperature from increasing due to Al ₂ O ₃ . The addition of 1 to 5% by weight is effective, but if it exceeds 5% by weight, the bending strength is lowered.

Further, it is also possible to obtain a similar dielectric material with a low dielectric constant by crystallizing glass (A) in advance and pulverizing it to obtain a glass-ceramic dielectric material (B) and sintering it. .

The glass (A) and the glass-ceramic (B) may be used alone, or may be used as a mixture of both. When the glass (A) is used alone, the binder removal during firing tends to be insufficient, and carbon tends to remain in the fired body, so glass-ceramics (B) or crystallized in advance as a filler or , And it is desirable to use it by mixing with other commonly used crystalline filler. In particular, when glass-ceramics (B) is used as a filler, it is advantageous because it becomes a homogenous body after firing and does not significantly change the composition and characteristics, and it is possible to mix a large amount and freely select the mixing ratio. This is an advantage. These fillers have the effects of improving the binder removal property, mechanical strength, moldability, etc., and controlling the shrinkage ratio during firing.

The dielectric material of the present invention is used as a circuit board or a dielectric layer of a multilayer circuit.

For example, when used in a multilayer circuit board, the glass or glass-ceramics of the present invention is used in a pole mill to have an average particle size of 1
Grind to about 5 μm, add filler, binder, plasticizer, wetting agent to the obtained powder as needed, mix well in a solvent to make a slurry, and use a known method such as a doctor blade method. Mold to form a green sheet. A conductor is printed on the green sheet, a plurality of sheets are laminated, heated and pressed, and then fired to be integrated. The firing may be carried out at a crystallization temperature of glass or higher, for example, 1000
It can be fired at a low temperature of ℃ or less.

Depending on the conductor material used, the firing atmosphere may be an oxidizing atmosphere,
Although any non-oxidizing atmosphere may be used, the dielectric material of the present invention can obtain sufficiently high mechanical strength even when fired in a non-oxidizing atmosphere. A dielectric paste may be used instead of the green sheet to manufacture a multilayer circuit board by a paste laminating method.

EXAMPLES Example _{1 Mg (OH) 2, B} 2 O 3, SiO 2, BaCO 3, Zr
O ₂ , Al ₂ O ₃ and CaCO ₃ were weighed in the proportions shown in Table 1 in terms of oxides, mixed in an automatic mortar and mixed in a platinum crucible for 15
After being kept at 00 ° C. for 30 minutes to be melted, the glass was rapidly cooled by twin rolls. This glass was roughly crushed with a stamp mill and then with an alumina pole mill for 48 hours using methanol as a solvent to obtain a glass powder (A) having an average particle diameter of 2.5 μm.

On the other hand, a glass having the same composition as this was prepared, coarsely crushed, heat-treated at 900 ° C. for 30 minutes to crystallize, and crushed again to obtain a glass-ceramic powder (B) having an average particle diameter of 2.5 μm.

Glass powder (A) 50 parts by weight, glass-ceramic powder (B)
50 parts by weight, 12 parts by weight of acrylic resin, 3 parts by weight of phthalic acid plasticizer, and 28 parts by weight of ketone solvent were thoroughly mixed using an alumina pole mill to form a slurry. Then, when defoaming and viscosity adjustment were performed, a green sheet having a thickness of 150 μm was prepared by the doctor blade method. Six green sheets were heated and laminated at a temperature of 80 ° C. and a pressure of 100 kg / cm ² to obtain an unsintered substrate.

This was held in a belt furnace at 600 ° C for 2.5 hours to remove organic substances, and then at a temperature shown in Table 1 in a nitrogen atmosphere at 2.5 ° C.
Firing was performed while holding the time.

The relative permittivity, insulation resistance and bending strength of each of the obtained fired bodies were measured, and the results are shown in Table 1.

Examples 2 to 5 Green sheets were prepared in the same manner as in Example 1 except that the glass composition was changed as shown in Table 1, laminated, and fired.
The characteristics of the obtained fired body were measured, and the results are also shown in Table 1.

Comparative Example _{1~3 MgO, B 2 O 3,} SiO 2, BaCO 3, ZrO 2, Al 2
O ₃ and CaO were mixed in the proportions shown in Table 1, a green sheet was prepared in the same manner as in the example, laminated and then fired. The characteristics of the obtained fired body were measured, and the results are shown in Table 1.
Are also shown.

As is clear from Table 1, the dielectric material of the present invention has excellent characteristics as a circuit board material, and in particular, the addition of Al ₂ O ₃ significantly improved the bending strength. In Comparative Example 3, Al
_Since the addition amount of ₂ O ₃ was large, the firing temperature was high, and sintering did not occur even at 1100 ° C.

Examples 6 to 9 Green sheets were produced in the same manner as in Example 1 except that the ratio of the glass powder (A) and the glass-ceramic powder (B) was changed and the results were as shown in Table 2, and the sheets were laminated and then fired.

The characteristics of the obtained dielectric are shown in Table 2.

Example 10 Glass powder having the same composition as in Example 1 and an average particle size of 1.0 μm
The zirconium silicate powder (1) was mixed at a weight ratio of 50:50 to prepare a green sheet in the same manner as in Example 1, laminated and then fired at 980 ° C. for 2.5 hours. The relative permittivity, insulation resistance and bending strength of the obtained fired body are 7.8 and 10 ¹⁴ Ωc, respectively.
It was 2100 Kg / cm ² over m.

Effects of the Invention The dielectric material of the present invention has excellent electrical properties and high mechanical strength, and since it can be sintered at low temperatures,
Metals having low conductor resistance such as Ag, Au, and Cu can be used as wiring materials, and are extremely useful as circuit board materials capable of high-density mounting.

Claims (2)

[Claims] 1. (A) Magnesium, boron, silicon, barium, zirconium, aluminum and calcium are converted into oxides in an amount of 20-40% by weight of MgO, 10-30% by weight of B ₂ O _{3 and} 10-35% by weight of SiO _2. %, BaO 5 to 22% by weight, ZrO ₂ 5 to 20% by weight, Al ₂ O ₃ 2 to 15% by weight, CaO 0 to 5% by weight, and a glass of (B) (A). A dielectric material for a circuit board, which comprises one or more selected from glass-ceramics obtained by heat treatment and crystallization in advance. 2. (1) (A) Magnesium, boron, silicon, barium, zirconium, aluminum and calcium are converted into oxides in an amount of 20 to 40% by weight of MgO, 10 to 30% by weight of B ₂ O ₃ , and SiO ₂ 10 Glass containing 5 to 35% by weight, BaO 5 to 22% by weight, ZrO ₂ 5 to 20% by weight, Al ₂ O ₃ 2 to 15% by weight, CaO 0 to 5% by weight, and (B) (A) 1. A dielectric material for a circuit board, comprising one or more selected from glass-ceramics obtained by preliminarily heat-treating and crystallizing the glass, and (2) a crystalline filler.