JPH0517211A - Substrate material and circuit substrate - Google Patents

Abstract

PURPOSE:To ensure a low dielectric constant, to increase signal processing speed and to enhance yield and reliability by mixing specified powder with crystalline mullite and/or forsterite and sintering this mixture. CONSTITUTION:Glass forming powder is obtd. by blending compds. so that 60-80wt.% SiO2, 0-4wt.% Al2O3, 0-3wt % K2O, 0-3wt.% Li2O and 15-30wt.% B2O3 are contained by >=95wt.% total amt. when the compds. are expressed in terms of oxides and 50-70wt.% of the powder is mixed with 30-50wt.% crystalline mullite and/or forsterite to obtain a starting material mixture. This mixture is melted at 1,450-1,550 deg.C and water-ground and the resulting glass is sintered at 850-1,000 deg.C to produce a substrate material. When this material is laminated and copper or silver is disposed as an internal conductor, a circuit substrate is produced.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a substrate material and a circuit board,
More specifically, the present invention relates to a board material which is useful for a multilayer wiring circuit board and the like and has good compatibility with a conductor material such as copper or silver, and a circuit board using the same.

[0002]

2. Description of the Related Art Generally, alumina has been conventionally used as a material for a multilayer ceramic substrate and refractory metals such as tungsten and molybdenum have been used as circuit conductors. From the standpoint of achieving higher integration and higher integration, these conductor materials have problems such as high internal resistance. Therefore, copper, silver, or the like has begun to be used as an inexpensive conductor material having a low electric resistance. However, in order to use copper or silver, it is necessary to set the firing temperature of the substrate that is fired at the same time as these conductors to about 850 to 1000 ° C., which is the firing temperature of copper paste, etc. Many substrate materials have been studied.

For example, in JP-A-59-162169, an inorganic material comprising at least one of cristobalite, quartz, beryllia, corundum, magnesia, stabilized zirconia, thoria, steatite, forsterite, spinel and zircon porcelain. A substrate material has been proposed which is composed of a filler and a low melting point glass and can be sintered at 1000 ° C or lower. However, in this case, it was not possible to control the cristobalite precipitation when borosilicate glass was used as the low melting point glass. Generally, when borosilicate glass is fired at a high temperature, cristobalite is precipitated and the coefficient of thermal expansion tends to be too large.

Further, in JP-A-64-87555, a mullite-borosilicate glass composite is added to a ceramic powder such as alumina, forsterite and steatite and / or a ceramic such as quartz, cordierite and β-spodement. It has been shown that the addition of powder improves substrate strength.

Further, in Japanese Patent Application Laid-Open No. 2-141458, SiO ₂ is 50 when the glass composition is converted into oxide.
~70wt%, Al ₂ O ₃ is 5 to 20 wt%, CaO is 5-25 wt%, MgO is 0~5wt%, B ₂ O ₃ is 8
It has been shown that the addition of an inorganic filler in an amount of ˜13 wt% enables simultaneous firing with a conductor having good conductivity such as copper, and a substrate material without warpage and bending can be obtained.

[0006]

When a substrate material having a low firing temperature is used as a laminated substrate material for the interior of a circuit conductor, the glass material alone is insufficient in strength, so that it cannot be combined with ceramic powder. In the above-mentioned glass / ceramic composite substrate material, which is required, adjustment of the firing temperature and smoothness of the sintered body are mainly studied. On the other hand, it is necessary to lower the permittivity of the substrate material in order to respond to the speeding up of signal processing, but we will consider a substrate material that satisfies all characteristics of sintering temperature, smoothness and low permittivity. However, the glass composition is mainly required to be appropriate for lowering the dielectric constant.

When a ceramics substrate is formed using these substrate materials and made into a component, the pinning strength of pins serving as electrodes is required. Thermal expansion of the ceramics substrate and silicon generally used as a semiconductor chip. If the coefficients are perfectly matched, there is a problem that residual thermal stress is generated between the material such as the pins and the like, causing damage to the components, and reducing the reliability of the substrate and the yield of products.

The present invention has been invented in view of the above problems, and is capable of low temperature co-firing with a conductor such as copper or silver, has a low dielectric constant, and is used as a semiconductor chip. And a metal such as a conductor or a pin have a coefficient of thermal expansion intermediate between them and the difference in coefficient of thermal expansion between them is small, so that a highly reliable product can be made of a substrate material and a conductor such as copper or silver as an internal conductor. It is intended to provide a circuit board in which is used.

[0009]

In order to achieve the above object, the substrate material according to the present invention comprises, in terms of oxide, 60 to 80 wt% of SiO _{2, 0} to 4 wt% of Al ₂ O ₃ , and K ₂ O.
Is 0 to 3 wt%, Li ₂ O is 0 to ₃ wt%, and B ₂ O ₃ is in the composition range of 15 to ₃₀ wt%, the total amount is 95 wt%.
50 to 70 wt% of the above glass composition powder and 30 to 30 of crystalline mullite and / or forsterite
It is characterized in that it is a sintered body of a raw material mixture consisting of 50 wt%, and further, the circuit board according to the present invention is characterized in that the above board materials are laminated and copper or silver is used as an internal conductor. There is.

Generally, the dielectric constant and the thermal expansion coefficient of a material are their own physical property values, which greatly depend on the composition. For composites, the rules of mixing vary, but in many cases chemical reactions during sintering give rise to different substances than at the start, and their properties deviate from the rules of mixing. As a result of various studies on the glass composition, the present inventors have found that the above glass composition has suitable characteristics as a substrate material that can be co-fired with a copper or silver conductor. Furthermore, by adding mullite and / or forsterite, one having excellent co-sinterability with a conductor such as copper or silver and strength can be obtained, and the thermal expansion coefficient of the substrate material is adjusted to be between that of silicon and metal. The present invention has been made, and it has been found that the stability in wire bonding, pin stand, etc. is also improved.

[0011]

According to the above-mentioned structure, SiO is calculated in terms of oxide.
₂ is 60-80 wt%, Al ₂ O ₃ is 0-4 wt%, K ₂
O is 0 to 3 wt%, Li ₂ O is 0 to ₃ wt%, B ₂ O ₃
The total amount of the composition range of 15 to 30 wt% is 95w
50 to 70 wt% of a glass composition powder of t% or more,
Crystalline mullite and / or forsterite 3
Since it is a sintered body of a raw material mixture consisting of 0 to 50 wt%, it can be co-fired at low temperature with a conductor such as copper and silver, has a low dielectric constant, and silicon and conductors used as a semiconductor chip. The difference in the coefficient of thermal expansion with the metal such as the pin is also small.

According to the circuit board having the above structure,
Since the above substrate materials are laminated and copper or silver is used as the internal conductor, a product having low electric resistance, low cost and stable characteristics can be obtained.

The limitation of each component to the above range is due to S
When the content of iO ₂ is less than 60 wt% in the glass composition, the chemical stability of glass deteriorates and the coefficient of thermal expansion increases.
On the other hand, when it exceeds 80 wt%, the softening temperature rises to 100
This is because densification does not occur sufficiently at a firing temperature of 0 ° C or lower.

Further, the mechanical strength by containing the Al ₂ O ₃ is increased, the content of Al ₂ O ₃ is softening point exceeds 4 wt% in the glass composition is increased.

Further, the softening point of the glass is lowered by adding K ₂ O and Li ₂ O, but K ₂ O and L
If the content of i ₂ O exceeds 3 wt% in the glass composition, the chemical stability is lowered, and particularly the reaction with the added ceramics occurs, and the thermal expansion coefficient and the like increase.

Further, the addition of B ₂ O ₃ lowers the softening point of the glass and facilitates the production of a glass frit. However, when the content of B ₂ O ₃ is less than 15 wt% in the glass composition, it is 900 ° C. Has a high viscosity, resulting in insufficient densification of the substrate. On the other hand, when it exceeds 30 wt%, the dielectric constant increases,
It is not suitable as a substrate material.

Further, the glass composition powder is added to the raw material mixture 5
If it is less than 0 wt%, it will not be sufficiently densified at a sintering temperature of 1000 ° C or lower. On the other hand, if it exceeds 70 wt%, it will be 85
Since the substrate is deformed by the softening of the glass at a temperature lower than 0 ° C., it is impossible to co-fire with a conductor such as copper or silver.

Furthermore, the addition of mullite improves the mechanical strength, suppresses the precipitation of cristobalite that occurs during the glass cooling process, and suppresses the coefficient of thermal expansion of the substrate material to be low. Also, the addition of forsterite improves the strength of the substrate material, and
It is possible to prevent the coefficient of thermal expansion from becoming too low only with the glass component and mullite, and the coefficient of thermal expansion is increased so that it can be adjusted between silicon and metal. Therefore, 30 to 50 wt% of mullite and / or forsterite
By setting the above, the desired thermal expansion coefficient and relative permittivity can be obtained.

Mullite and forsterite are added in crystalline form, respectively. The crystalline is superior to the glass in mechanical strength, and the glass composition alone has insufficient strength in combination with crystalline ceramics. This is because it will be improved as a result.

[0020]

EXAMPLES Examples according to the present invention will be described below together with comparative examples. First, the raw materials were mixed so as to have the composition shown in Table 1, melted at a temperature of 1450 to 1550 ° C., and water-granulated to obtain glass.

[0021]

[Table 1]

In the table, * marks are within the scope of the present invention,
Other than that, those outside the scope of the present invention are shown.

As is clear from Table 1, the glass obtained with the composition within the scope of the present invention is suitable for producing the target low temperature firing, low dielectric constant substrate material.

Further, the glass composition obtained in Sample No. 1 and mullite and forsterite having the compositions shown in Table 2 were pulverized and mixed in a ball mill, xylene and butanol were used as solvents, an acrylic resin was added, and a doctor was added. A 200 μm thick green sheet was prepared by the blade method.
Further, 3 to 10 layers of green sheets, laminated by pressing, were fired in N ₂ gas at 850 to 1000 ° C. to prepare a substrate material.

The density and porosity of each of the obtained substrate materials were measured to evaluate the sinterability. The relative permittivity was evaluated with an impedance analyzer and the thermal expansion coefficient was evaluated with a thermal expansion meter.

Further, using the green sheet prepared as described above, a copper conductor or a silver conductor is used as an inner conductor, and
A co-fired ceramic substrate was obtained by stacking 0 layers.
The characteristics of the circuit board obtained by mounting a silicon chip on the obtained ceramic substrate were evaluated as matching between silicon and electrodes. The results are shown in Table 2.

[0027]

[Table 2]

In the table, * marks are within the scope of the present invention,
Other than that, those outside the scope of the present invention are shown. As is clear from Table 2, all the substrate materials prepared with the composition within the range of the present invention are excellent in sinterability, dielectric constant and thermal expansion coefficient. Further, it can be seen that it is also effective as a co-firing circuit board using a copper conductor or a silver conductor.

The substrate material formed by such a composition can be co-fired at a low temperature with a conductor such as copper or silver,
Since a low dielectric constant can be realized, it becomes possible to cope with speeding up of signal processing. Further, since it is possible to reduce the difference in the coefficient of thermal expansion between silicon and a metal such as a conductor or a pin which is generally used as a semiconductor chip, a difference occurs between the substrate and silicon, and between the substrate and the metal such as a conductor or a pin. Residual thermal stress can be suppressed. Therefore, it is possible to manufacture a highly reliable product. Furthermore, since copper or silver is used as the inner conductor,
An inexpensive circuit board having a low electric resistance can be obtained.

[0030]

As described above in detail, in the substrate material according to the present invention, SiO ₂ is 60 to 80 w in terms of oxide.
t%, Al ₂ O ₃ is 0 to 4 wt%, K ₂ O is 0 to ₃ wt%.
%, Li ₂ O is 0 to ₃ wt%, B ₂ O ₃ is 15 to ₃₀ w
Since it is a sintered body of a raw material mixture consisting of 50 to 70 wt% of a glass composition powder whose total amount in the composition range of t% is 95 wt% or more, and 30 to 50 wt% of crystalline mullite and / or forsterite. It is possible to perform low temperature co-firing with conductors such as copper, silver and the like, and it is possible to realize a low dielectric constant and to cope with high-speed signal processing. Further, it is possible to adjust the difference in thermal expansion coefficient between silicon used as a semiconductor chip and a metal such as a conductor or a pin, which improves the yield in pin-bonding and wire-bonding. Can be provided.

Further, in the circuit board according to the present invention, since the above board materials are laminated and copper or silver is used as the internal conductor, a product having a small electric resistance, an inexpensive price and stable characteristics Can be provided.

Claims (2)

[Claims] 1. SiO ₂ is 60 to 80 w in terms of oxide.
t%, Al ₂ O ₃ is 0 to 4 wt%, K ₂ O is 0 to ₃ wt%.
%, Li ₂ O is 0 to ₃ wt%, B ₂ O ₃ is 15 to ₃₀ w
It should be a sintered body of a raw material mixture consisting of 50 to 70 wt% of a glass composition powder having a total content of 95 wt% or more in the composition range of t% and 30 to 50 wt% of crystalline mullite and / or forsterite. Substrate material characterized by. 2. The substrate material according to claim 1, which is laminated,
A circuit board using copper or silver as an inner conductor.