JP2003073163A - Low temperature sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low temperature sintered compact having sufficient mechanical strength for a multilayer circuit board, low relative permittivity at a high frequency region, and also low and stable tangent of dielectric loss, capable of manufacturing by firing at a low temperature of 800-1000 deg.C, and multilayering using gold (Au), silver (Ag) or copper (Cu) for wiring conductor. SOLUTION: The low temperature sintered compact manufactured by firing at a low temperature of 800-1000 deg.C, contains a gahnite crystal phase 1 as a principal crystal phase, Zn2 SiO4 crystal phase 2, cordierite crystal phase 3, and glass phase 4, permittivity is <6, tangent of dielectric loss is <=10×10<-4> at 3GH, and strength is 25 kg/mm<2> , can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low temperature sintered body for a multi-layer circuit board, and is particularly applied to a multi-layer composite circuit board on which semiconductor elements and various electronic components are mounted. The present invention relates to a high-temperature low-temperature sintered body capable of copper wiring.

[0002]

2. Description of the Related Art In recent years, with the advent of advanced information technology, information transmission has become faster and higher in frequency, semiconductor elements to be mounted have become faster and more highly integrated, and higher packaging density has been required. As a result, various circuit boards made of alumina, which have been frequently used, have a relative permittivity of 9 to 9 at 3 GHz.
Since the dielectric constant is 9.5, which is considerably large, it is said to be unsuitable for recent high frequency circuit boards and the like.

That is, in order to propagate a signal at high speed, the substrate material is required to have a lower dielectric constant.
Higher mechanical strength in order to prevent the substrate itself from being destroyed or chipped from the stress applied to the substrate in the process of connecting various electronic components and input / output terminals to the multilayer circuit substrate. Is also required.

Therefore, in order to satisfy the above requirements, for example, a glass sintered body made of a glass composition containing SiO ₂ , Al ₂ O ₃ and MgO as a main component has been proposed. Although the body has the property of having a low dielectric constant, the problem of low mechanical strength remains, and it does not completely satisfy the above requirements, and various research and development have been advanced in order to solve the problem for that. There is.

As a result, as a composition having a low dielectric constant and high strength, for example, a glass composition in which mullite and cordierite are precipitated as a main crystal phase by heat treatment has been proposed (Japanese Patent Laid-Open No. 05-298919). See the bulletin).

[0006]

However, the multilayer circuit board made of the glass composition proposed above has a dielectric constant and a dielectric loss tangent which are required especially as a circuit board for high frequencies.
In addition, there is a problem that not all properties such as mechanical strength are necessarily satisfied.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its object is to have a sufficient mechanical strength as a multilayer circuit board, a low relative dielectric constant in a high frequency region, and a dielectric loss tangent. It also has the characteristic of low
To provide a low-temperature sintered body for high frequency, which can be produced by sintering at a low temperature of 800 to 1000 ° C., which enables multilayering using u), silver (Ag), and copper (Cu) as a wiring conductor. It is in.

[0008]

Means for Solving the Problems As a result of intensive studies on the above-mentioned problems, the present inventor has found that a high frequency can be obtained by precipitating a garnite crystal phase, a Zn ₂ SiO ₄ crystal phase and a cordierite crystal phase as crystal phases. Low relative permittivity in the region,
It has been found that the dielectric loss tangent can be lowered, and in particular, the strength can be increased by precipitating the garnite crystal phase which is a spinel type crystal.

That is, the present invention is a low temperature firing sintered body produced by firing at a low temperature of 800 to 1000 ° C., in which the garnite crystal phase is the main crystal phase and the Zn ₂ SiO ₄ crystal phase is
Including a cordierite crystal phase and a glass phase, and 3
Dielectric constant less than 6 GHz, dielectric loss tangent 10 × 10
^-4 or less, with a strength of 2
It is characterized by being 5 kg / mm ² or more.

[0010]

According to the low temperature sintered body of the present invention, since zinc oxide is contained as a filler component, a garnite crystal phase exhibiting a low dielectric constant and a low dielectric loss tangent is precipitated as a main crystal phase, and further Zn ₂ SiO _{2 is formed. 4} By precipitating a crystal phase and then a cordierite crystal phase having a lower dielectric constant and a smaller dielectric loss tangent than the glass phase, it becomes possible to lower the dielectric constant and lower the dielectric tangent.

Further, by precipitating mainly the garnite crystal phase which is a spinel type crystal, the bending strength of the sintered body can be increased.

Further, the low temperature sintered body of the present invention is 800
Since it can be fired simultaneously with the internal wiring conductors of Au, Ag, or Cu at a low temperature of up to 1000 ° C., it is possible to easily achieve fine wiring of a multilayer circuit board or a package for housing a semiconductor element, which includes these wiring conductors. .

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A schematic diagram of the structure of a low temperature sintered body of the present invention is shown in FIG. The low temperature firing sintered body of the present invention is shown in FIG.
As shown in FIG.
n ₂ SiO ₄ crystal phase 2, cordierite crystal phase 3,
It is composed of a glass phase 4.

According to the present invention, the presence of the garnite crystal phase in the sintered body, and at the same time the Zn ₂ SiO ₄ crystal phase and the cordierite crystal phase,
It is possible to obtain a low relative permittivity and a low dielectric loss tangent.

Further, by precipitating a garnite crystal phase which is a spinel type crystal phase in the sintered body, the network of each crystal phase can be reinforced and a sintered body having high mechanical strength can be obtained.

The low-temperature sintered body of the present invention has a dielectric constant of less than 6 and a dielectric loss tangent of 1 at a measurement frequency of 3 GHz.
It has characteristics of 0 × 10 ^-4 or less, and strength of 25 kg.
/ Mm ² or more.

Next, as a specific method for producing the low-temperature sintered body of the present invention, as a starting material, SiO ₂ -A is used.
l ₂ O ₃ -MgO-ZnO-B ₂ O ₃ based glass in 50 to 9
9.9% by weight, particularly preferably 60 to 95% by weight, and zinc oxide as a filler component are mixed in an amount of 0.1 to 50% by weight, especially ZnO in an amount of 5 to 40% by weight based on the total amount.

The filler component can be added in the form of ZnO powder, carbonate, nitrate, acetate or the like capable of forming ZnO during the sintering process. Since it is important for zinc oxide to precipitate a garnite crystal phase and a Zn ₂ SiO ₄ crystal phase by a reaction with glass, the zinc oxide powder has a particle size of 1.5 μm or less, particularly 1.0 μm or less. It is desirable that it is a fine powder.

Further, as a starting material, SiO ₂ --Al ₂ O
₃ to use -MgO-ZnO-B ₂ O ₃ based glass, spinel-type crystal phase is deposited by the use of glass of this system, the crystal phase present in the form of reinforcing the network of the glass, high-strength This is because the sintered body of can be obtained.

According to the invention, at least SiO ₂ , A
The amount of glass containing l ₂ O ₃ , MgO, ZnO and B ₂ O ₃ is 5
If it is less than 0% by weight, in other words, if the amount of Zn converted to oxide is more than 50% by weight, it is 800 to 1000 ° C.
The porcelain cannot be fully densified at this temperature.

On the contrary, if the amount of glass is more than 99.9% by weight, in other words, the amount of Zn in terms of oxide is less than 0.
When it is less than 1% by weight, the dielectric loss tangent becomes larger than 10 × 10 ⁻⁴ .

Therefore, the content of the glass is 50 to 9
It is specified to be 9.9% by weight, and more preferably in the range of 60 to 95% by weight.

On the other hand, as a more specific composition of the glass, SiO ₂ is 40 to 50% by weight and Al ₂ O ₃ is 25 to ₃ %.
0 wt%, MgO 8-12 wt%, ZnO 6-9 wt%, and B ₂ O ₃ 8-11 wt% are desirable.

After appropriately adding a binder to the mixed powder which has been added and mixed in the above proportions, it is molded into a predetermined shape and N
₂ , 800 to 100 in a non-oxidizing atmosphere such as Ar
Baking at a temperature of 0 ° C. for 0.1 to 5 hours. If the firing temperature at this time is lower than 800 ° C, the porcelain will not be sufficiently densified and
If the temperature exceeds 000 ° C, the conductors of gold, silver and copper cannot be used.

In the case of producing a wiring board using the low temperature sintered body of the present invention, for example, the mixed powder prepared as described above is subjected to a known tape forming method such as a doctor blade method or a rolling method. Etc., a green sheet for forming an insulating layer is formed, and then a powder of Au, Ag or Cu, especially Cu
A wiring pattern is formed on the surface of the sheet by means of screen printing, gravure printing, offset printing or the like using a metal paste containing powder, and in some cases a through hole is formed in the sheet to fill the hole with the paste. After that, a plurality of sheets are laminated and pressure-bonded, and then the wiring layer and the insulating layer can be simultaneously fired by firing under the above-described conditions.

[0026]

EXAMPLES The low temperature sintered body of the present invention will be described in detail below. _{First, SiO 2 -Al 2 O 3 -MgO} -Z
As nO-B ₂ O ₃ based crystalline glass, crystalline glass A: SiO ₂ 44 wt% -Al ₂ O ₃ 29 wt% -MgO11 wt% -ZnO 7 wt% -B ₂ O ₃ 9 wt% crystalline glass B: Two kinds of glass of 50% by weight of SiO ₂ -25% by weight of Al ₂ O ₃ -9% by weight of MgO -8% by weight of ZnO -8% by weight of B ₂ O ₃ and ZnO having an average particle size of 1 μm or less are shown in Table 1. Mixed according to composition.

Then, an organic binder, a plasticizer, and toluene were added to this mixture, and a green sheet having a thickness of 300 μm was prepared by the doctor blade method. Then, 5 sheets of this green sheet are laminated and 100 at a temperature of 50.
A pressure of kg / cm ² was applied for thermocompression bonding. The obtained laminated body was debindered in a water vapor-containing / nitrogen atmosphere at a temperature of 700 ° C., and then fired in dry nitrogen under the conditions shown in Table 1 to obtain a sintered body.

The dielectric constant, dielectric loss tangent, and bending strength of the obtained sintered body were evaluated by the following methods. The dielectric constant and the dielectric loss tangent were measured by cutting out a sample having a diameter of 50 mm and a thickness of 1 mm from the sintered body, and measuring it at 3.0 GHz by a cavity resonator method using a network analyzer and a synthesized sweeper. In the measurement, the sample dielectric substrate was sandwiched between the sapphire-filled cylindrical resonators, and the permittivity and the dielectric loss tangent were calculated from the resonator's TE011 mode resonance characteristics.

The bending strength is 70 m from the sintered body.
m, thickness 3 mm, width 4 mm to prepare a measurement sample, JIS
A 3-point bending test was performed according to the regulations of C-2141.

As a comparative example, the filler component was Zn.
Instead of O, CaO and SiO ₂ were used, and a sintered body was prepared and evaluated in the same manner as above.

Further, instead of the crystalline glass, crystalline glass C: SiO ₂ 55.2% by weight-Al ₂ O ₃ 12% by weight-B ₂ O ₃ 4.4% by weight-BaO 20% by weight-ZnO 6.7 wt% -Na ₂ O 1.6 wt% -ZrO ₂ 0.1 wt% crystalline glass D: SiO ₂ 60.7 wt% -Al ₂ O ₃ 9.3 wt% -B ₂ O ₃ 5 wt% - SrO 15.4 wt% -ZnO 8.6 wt% -K ₂ O 1 wt% two kinds of glass were used, and CaO and SiO ₂ having an average particle diameter of 1.0 μm were further used as fillers, and similarly evaluated. .

[0032]

[Table 1]

As is clear from the results shown in Table 1, in the present invention in which the garnite crystal phase, the Zn ₂ SiO ₄ crystal phase and the cordierite crystal phase were precipitated as the crystal phases, the dielectric constant was less than 6 and the dielectric loss tangent was all in the present invention. Is 10 × 10 ⁻⁴ or less, strength is 2
It shows a high value of 5 kg / mm ² or more. Among these, those having a firing temperature of 850 to 900 ° C. have a dielectric constant of 5.4 or less and a dielectric loss tangent of 9 × 10 ⁻⁴ or less, which are more excellent in dielectric properties. .

On the other hand, in sample No. 1 in which the amount of glass is less than 50% by weight, it cannot be densified unless the firing temperature is raised to 1400 ° C., the dielectric loss tangent is extremely high, and the amount of glass is 99. When it exceeds 9% by weight, the dielectric loss tangent becomes larger than 10 × 10 ⁻⁴ and sufficient strength cannot be secured.

As a comparative example, sample No. 23 using CaO as a filler has a large permittivity of 7.0, which is the same as S.
The sample No. 24 using iO ₂ has a dielectric loss tangent of 50 × 1.
It was quite high, ^0-4 .

Further, the sample numbers 17 to 22 of the comparative examples using the crystalline glasses C and D could not be sufficiently densified at 800 to 1000 ° C., and all of them had a low dielectric constant, a low dielectric loss tangent and a high strength. No body could be obtained.

[0037]

As described in detail above, the low-temperature fired sintered body of the present invention has a low dielectric constant and a low dielectric loss tangent in the high frequency region, and is therefore suitable for microwave circuit elements and the like. By increasing the strength, the leads can be joined to the input / output terminals, the reliability of the board during mounting can be improved, and since it can be fired at a low temperature of 800 to 1000 ° C, wiring conductors made of Au, Ag, Cu, etc. can be used at the same time. It can be formed by firing and can be applied as a substrate for various multilayer wiring boards and semiconductor element housing packages.

[Brief description of drawings]

FIG. 1 is a schematic view of a structure of a low temperature sintered body of the present invention.

[Explanation of symbols]

1 Garnite crystal phase 2 Zn ₂ SiO ₄ crystal phase 3 Cordierite crystal phase 4 Glass phase

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 3/46 C04B 35/00 PF term (reference) 4G030 AA07 AA08 AA32 AA35 AA36 AA37 BA09 BA12 CA01 CA08 GA27 HA18 HA25 5E346 AA12 BB01 CC18 CC32 CC38 CC39 DD02 DD34 EE24 EE29 GG02 GG04 HH06 HH11 5G303 AA05 AB06 AB07 AB15 BA09 CA03 CB01 CB02 CB17 CB30 CB38

Claims (2)

[Claims] 1. A low-temperature fired sintered body produced by firing at a low temperature of 800 to 1000 ° C., wherein a garnite crystal phase is a main crystal phase, a Zn ₂ SiO ₄ crystal phase, and a cordierite crystal phase. And a glass phase, a dielectric constant at 3 GHz of less than 6, and a dielectric loss tangent of 10 × 10 ⁻⁴ or less. 2. The low temperature sintered body according to claim 1, which has a strength of 25 kg / mm ² or more.