JPH08225364A - Ceramic substrate for wiring circuit - Google Patents

Abstract

PURPOSE: To produce a ceramic substrate for wiring circuit having low relative permittivity, high strength and excellent reliability by forming a layer of an electrically conductive material on a substrate consisting of a ceramic sintered material containing mullite, a glass component and specific multiple oxides in specified ratios. CONSTITUTION: A ceramic sintered material containing 66.5-80.7wt.% of mullite, 15-29.2wt.% of a glass component, 4.3-18.5wt.% of multiple oxides consisting of aluminum oxide and silicon dioxide in a molar ratio of 1/0.7-1, and preferably at least one selected from an alkaline earth metal oxide (e.g. magnesium oxide) and an alkali metal oxide (e.g. sodium oxide), wherein the total amount of the latter oxides is 1wt.% or less than 1wt.% in terms of oxide, is produced. Subsequently, a layer of an electrically conductive material (e.g. a tungsten layer) is formed on a substrate comprising of the ceramic sintered material to obtain a ceramic substrate for a wiring circuit. This enables the prevention of the crack formation caused by the difference of thermal expansion coefficients between a ceramic insulating material and a wiring conductive material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel ceramic substrate for a wiring circuit, and in particular, has a high-density wiring, and has a function of mounting pins for inputting and outputting electric signals and mounting semiconductor components. The present invention relates to a ceramic substrate for a wiring circuit suitable for forming a module.

[0002]

2. Description of the Related Art In recent years, integrated circuits such as LSIs have become faster and faster.
With the increase in density, a method of directly mounting a chip on a ceramic substrate has been used in order to measure heat radiation and increase the speed of elements. However, in this mounting method, as the size of the integrated circuit such as the LSI increases, the stress caused by the temperature change during mounting between the integrated circuit material such as the LSI and the ceramic multilayer wiring circuit board material increases. There was a point. That is, the thermal expansion coefficient of alumina, which has been conventionally used as an insulating material of a ceramic multilayer wiring circuit board, is 75 ×
10 to ⁷ / ° C (room temperature to 500 ° C), and this value is LSI
Thermal expansion coefficient of silicon which is an integrated circuit material such as 35 × 1
Since it is more than twice as large as 0 to ⁷ / ° C (room temperature to 500 ° C), the stress caused by temperature change during mounting increases.
There has been a problem that the reliability of the connection portion has been reduced. The firing temperature of the alumina-based material is 1500 to 1650 ° C., and a conductor material that can be applied to simultaneously form the wiring circuit and the ceramic structure is tungsten or molybdenum. However, 45 × thermal expansion coefficient of tungsten or molybdenum, respectively ^{10 ~ 7, 54 × 10 ~} 7 /
C. (room temperature to 500.degree. C.), and when co-firing with the alumina-based material, there was a problem that cracks were generated inside the wiring board due to the difference in thermal expansion coefficient between them. Further, a problem of a substrate using a sintered body containing alumina as a main component as an insulating material is that the propagation speed of an electric signal is low. This is because the relative dielectric constant of alumina itself is 9.5%. (1
MHz).

[0003] Accordingly, Japanese Patent Application Laid-Open No. 55-139709 entitled "Mullite substrate manufacturing method" is an example of a substrate having a thermal expansion coefficient of a ceramic material close to that of silicon and having a small relative dielectric constant. According to this publication, since cordierite is generated between mullite main crystals, the cordierite has a coefficient of thermal expansion of 10 to 20 × 10 ⁷ / ° C. (room temperature to 5 ° C.).
Since the thermal expansion coefficient of the mullite substrate is lower than that of mullite alone by utilizing the fact that the temperature is 00 ° C.), a thermal expansion coefficient of 38 to 39 × 10 ⁷ / ° C. close to that of silicon is obtained.

[0004]

However, despite the above advantages, a ceramic circuit board formed by simultaneously firing a ceramic material and a conductor material cannot be formed.
This is because it must be fired at a temperature around 1500 ° C. where the cordierite phase exists, and cannot be fired simultaneously with tungsten or molybdenum, which is a conductor material that is difficult to sinter. Further, since the coefficient of thermal expansion of tungsten or molybdenum is 45 × 10 to ⁷ / ° C. and 54 × 10 to ⁷ / ° C., respectively, the difference in thermal expansion is large, and cracks are generated during simultaneous firing with alumina. .

Therefore, an object of the present invention is to provide a ceramic substrate for a wiring circuit, which has a coefficient of thermal expansion close to that of tungsten or molybdenum and has a low relative dielectric constant and high strength.

[0006]

According to the present invention, there is provided a composite oxide containing mullite as a main component, silicon dioxide, aluminum oxide and silicon dioxide in a molar ratio of 1: 0.7 to 1, and an alkaline earth element. A ceramic substrate containing a metal oxide,
Provided is a ceramic substrate for a wired circuit, which has a conductor layer formed on the substrate.

The mullite is made of aluminum oxide (Al ₂
O ₃ ) and silicon dioxide (SiO ₂ ) have a composition of 3 or more and less than 4 to 2 in a molar ratio, and the content is preferably 70% by weight or more. In particular, mullite has a ratio of Al ₂ O ₃ to SiO ₂ of 3 to 3.
3.5 to 2 is preferred.

The silicon dioxide (SiO ₂ ) is 30% by weight.
It is preferable that it is amorphous (glass) and is formed at the grain boundary of the mullite crystal. In particular, 15 to 30
Weight percent is preferred.

The composite oxide is preferably at least one of andalusite, kyanite and sillimanite. Mullite stoichiometrically aluminum oxide (Al ₂ O ₃₎ rich 3Al ₂ O ₃ · 2SiO ₂ are preferred, composite oxide Al ₂ O ₃ · SiO ₂ is preferred. Al ₂
O ₃ · SiO ₂ is preferably 1 to 15 wt%.

According to the present invention, mullite is a main component,
At least one selected from the group consisting of silicon dioxide, a composite oxide of aluminum oxide and silicon dioxide in a molar ratio of 1: 0.7 to 1, aluminum oxide, and an alkali metal oxide and an alkaline earth metal oxide; Provided is a wiring circuit ceramic substrate having a ceramic substrate contained therein and a conductor layer formed on the substrate.

The above ceramic substrate is, by weight, 70% or more of mullite (3Al ₂ O ₃ .2SiO ₂ ), 30% or less of silicon dioxide (SiO ₂ ), and a composite oxide (Al ₂ O ₃ .Si).
O ₂ ) 30% or less, aluminum oxide 15% or less, and preferably 1% or less of at least one selected from alkali metal oxides and alkaline earth metal oxides.

In particular, mullite 70% or more, SiO ₂ 15
% Or less, made of _{Al 2 O 3 · SiO 2 10} % or less, Al ₂
It is preferred that 5% or less of O ₃ and 1% or less of an alkaline earth metal oxide or an alkali metal oxide are substantially dissolved in mullite and do not exist as another crystal phase.

It is preferable that the alkali metal oxide and the alkaline earth metal oxide are substantially completely dissolved in the mullite. Alkali metal oxides include lithium, sodium, potassium, rubidium and cesium oxides, and alkaline earth metal oxides include beryllium, magnesium, calcium, strontium and barium oxides.

According to the present invention, 70% or more of mullite powder having an average particle size of 5 μm or less, 30% or less of silicon dioxide powder having an average particle size of 2 μm or less, 15% or less of aluminum oxide powder having an average particle size of 1 μm or less, and alkali A method for manufacturing a ceramic circuit board for a wiring circuit includes forming a mixed powder containing 1% or less of an earth metal oxide powder under pressure, firing, and then forming a conductor layer on the obtained ceramic substrate.

The firing temperature is preferably 1550 to 1680 ° C., and more preferably 1580 to 1620 ° C.

[0016]

The aluminum oxide is used as a sintering aid for mullite to produce mullite and sillimanite.

The addition of SiO ₂ lowers the dielectric constant, suppresses grain growth during sintering of mullite, and improves strength.
SiO ₂ is preferably 10% to 30%. If it is 40%, the strength is not preferable. In particular, when manufacturing a ceramic multilayer wiring circuit board, a ceramic multilayer wiring circuit board with high density wiring is manufactured by a method of laminating a large number of green sheets on which conductive wiring materials are printed.

However, when the internal wiring conductors are to be wired at a high density, cracks occur due to the difference in thermal expansion coefficient between the ceramic insulating material and the wiring conductor material. Using alumina as the ceramic insulating material, the wiring when the wiring at a high density using tungsten as the conductive material, the thermal expansion coefficient of alumina 75 × 10 ~ ⁷ / ℃ (room temperature to 500 ° C.) and tungsten thermal expansion coefficient 45 × 10 to ⁷ / ° C (room temperature to 500
° C), there was a problem that cracks were generated inside the substrate due to the thermal stress caused by the difference.

Therefore, it is necessary to develop a ceramic insulating material having a thermal expansion coefficient of 45 × 10 to ⁷ and 54 × 10 to ⁷ / ° C. of tungsten or molybdenum used for the internal wiring conductor material. Further, a ceramic insulating material having a thermal expansion coefficient close to that of a semiconductor component directly mounted on the ceramic multilayer printed circuit board by soldering or the like is required.

The thermal expansion coefficient of a ceramic insulating material containing alumina as a main component is 75 × 10 ⁷ / ° C. (room temperature to 500 ° C.)
Because it is, the thermal expansion coefficient of more than 2 times the thermal expansion coefficient of 35 × 10 ~ ⁷ / ℃ silicon semiconductor element is a semiconductor component (room temperature to 500 ° C.) are different. For this reason, there is a problem that stress generated due to a temperature change at the time of mounting is increased, reliability of a connection portion is reduced, and disconnection is caused.

In recent years, gallium-arsenic semiconductor elements have been used as semiconductor components. The gallium-arsenic semiconductor device has a coefficient of thermal expansion of 65 × 10 ⁷ / ° C. Therefore, when the silicon semiconductor element and the gallium-arsenic semiconductor element are mounted on the same substrate, the ceramic insulating material needs to be close to the coefficient of thermal expansion of these semiconductor elements.

Thermal expansion coefficient of silicon semiconductor device 35 × 1
0 to ⁷ / ° C and thermal expansion coefficient of gallium-arsenide semiconductor device of 65
× 10 ~ ⁷ / ceramic insulating material close Both the ° C. That is, the thermal expansion coefficient of 35~65 × 10 ~ ⁷ / ℃, preferably, should be a 40~60 × 10 ~ ⁷ / ℃ It is. This value, × 45 thermal expansion coefficient of tungsten or molybdenum with internal wiring conductor material ^10-7 /
℃ and close to 54 × 10 ~ ⁷ / ℃. As a ceramic insulating material having such a coefficient of thermal expansion, 42 to 45 × 10 to ⁷
3Al ₂ O ₃ · 2SiO ₂ or 35 having a thermal expansion coefficient of
Al ₂ O ₃ · Si having a coefficient of thermal expansion of ~ 75 × 10 ~ ⁷ / ° C
There is O ₂ etc.

The sintered body containing these crystal phases as main components is
It becomes a ceramic insulating material having a thermal expansion coefficient of 40 to 60 × 10 to ⁷ / ° C. Al ₂ O ₃ .SiO ₂ includes crystalline phases of andalusite, kyanite, and sillimanite, all of which have almost the same thermal expansion coefficient. Absent.

On the other hand, a ceramic multilayer wiring circuit board using a sintered body containing alumina as a main component as a ceramic insulating material has a large relative dielectric constant of alumina of 9.5 (1 MHz). Is slow.
In order to lower the relative permittivity, it is necessary to lower the relative permittivity of the crystal phase constituting the ceramic insulating material.

[0025] There are _{3Al 2 O 3 · 2SiO 2,} Al 2 O 3 · SiO 2 , etc. as tungsten or molybdenum conductive material simultaneously with the aluminosilicate material is less likely there relative dielectric constant that can be configured is used as a wiring conductor material.
These ceramic insulating materials have a relative dielectric constant of 6 to 7 (1 MHz). The ceramic insulating material composed of these crystal phases has a small relative permittivity and a ceramic multilayer wiring circuit board having a high electric signal propagation speed can be obtained.

As described above, even when performing multilayer wiring,
The ceramic substrate of the present invention is suitable.

Further, 3Al ₂ O ₃ .2SiO ₂ is converted to Al
_The amount of SiO ₂ added as a system for sintering with ₂ O ₃ , SiO ₂ , alkaline earth metal oxide or alkali metal oxide is increased, and after firing, 3Al ₂ O ₃ .2SiO ₂ and Al ₂ O ₃
· And to the formation of SiO ₂ in the crystal phase. However, when the amount of the alkali metal oxide or the alkaline earth metal oxide is large, the sinterability is improved, but a crystal phase or an amorphous composite oxide of these oxides and Al ₂ O ₃ or SiO ₂ is used. Is generated and the strength of the ceramic insulating material is reduced. Moreover, since the relative permittivity is also high, the total amount of alkali metal oxides and alkaline earth metal oxides is 1 wt% or less, and 3Al ₂ O ₃
· 2SiO may not exceed ₂ and Al ₂ O ₃ · SiO ₂ solid solution limit is required. That is, a ceramic insulating material containing no crystal phase composed of an alkali metal oxide or an alkaline earth metal oxide must be used. Further, in the ceramic insulating material containing more than 1 wt% of the alkali metal oxide and the alkaline earth metal oxide, the firing shrinkage rate varies and a stable sintered body can be obtained in the temperature range where the firing can be sufficiently performed. There wasn't. It was confirmed by X-ray diffraction that this was because the crystal phase in the sintered body was not stable.

Further, alkali metal oxides and alkaline earth metal oxides are very unstable substances in the air, and absorb moisture and the like when left unattended. Therefore, when these oxides are added, a method of adding them as a carbonate or a hydroxide is used. Carbonates or hydroxides are
Decomposes in the process of raising temperature and releases carbon dioxide or moisture. At this time, the oxide is in an active state and has an effect of improving sinterability.

Silicon dioxide (SiO ₂ ) has the lowest relative dielectric constant among oxides, and the relative dielectric constant of a ceramic insulating material can be reduced by increasing the amount of silicon oxide added. That is,
By adding SiO ₂ to 3Al ₂ O ₃ · 2SiO _2, it will be lower than the dielectric constant of 3Al ₂ O ₃ · 2SiO _2. Further, Al ₂ O ₃ or by diffusion reaction with 3Al ₂ O ₃ · 2SiO ₂ were added simultaneously by adding SiO _2, to produce a Al ₂ O ₃ · SiO ₂ crystal phase. Therefore, 3Al ₂ O ₃ · 2SiO ₂ in the ceramic insulating material
And it is 3Al ₂ O ₃ · SiO ₂ becomes crystal phase. These crystalline phases are very stable and do not change at temperatures around 1600 ° C. As a result, the firing shrinkage is stabilized by firing at a certain temperature or higher, and is promising as a ceramic multilayer wiring circuit board material. It was also found that the addition of a large amount of SiO ₂ has the effect of suppressing the grain growth of 3Al ₂ O ₃ .2SiO ₂ during firing. As a result, the relative permittivity was lowered and the strength was improved. It was found that the most effective effect was obtained by adding more than 75 wt% of the raw material components other than 3Al ₂ O ₃ .2SiO ₂ as the added amount of SiO ₂ .

In the method of manufacturing a ceramic multilayer wiring circuit board, it is necessary to first manufacture a green body (raw molded body), form a wiring conductor on the green body, laminate a large number of them at once, and perform simultaneous firing. Other than the green sheet method, there are a slip casting method, a die molding method by a pressing method, an injection molding method, and the like.

The green sheet method is a method in which a solvent and a thermoplastic resin are added to raw material powder, a stirred slurry is degassed, and then a green sheet is prepared by a green sheet preparing apparatus having a doctor blade.

The slip casting method is a method in which water, a dispersant and a resin such as a thermoplastic resin are added to raw material powder, and a stirred slurry is poured into, for example, a plaster mold.

In a press molding method, a solvent and a resin such as thermoplastic are added to the raw material powder, the raw material powder mixed and stirred by a grinder is sieved, granulated, and then put into a metal to reduce a load. In addition, it is a manufacturing method.

The injection molding method is a method in which a thermoplastic resin or wax is added to a raw material powder to perform injection molding.

Of course, a ceramic substrate for a wiring circuit in the case of not being multilayered can be manufactured by forming a wiring conductor on a green body and firing it.

[0036]

【Example】

(Embodiment 1) FIG. 1 is a sectional view showing one embodiment of a ceramic substrate for a wiring circuit according to the present invention. In the drawing, reference numeral 1 denotes a ceramic insulating material, and a bold line in the drawing denotes a wiring conductor material 8. These conductor layers are connected to each other by predetermined through-hole conductors indicated by bold lines in the vertical direction in the figure. Reference numeral 4 denotes a Kovar pin connected by a gold-indium braze 5 and 6 denotes a semiconductor component connected by a solder 7.

Next, an embodiment of the method for manufacturing a ceramic substrate for a wiring circuit according to the present invention will be described. In the following description,
Parts means parts by weight, and% means% by weight.

72 parts of slightly alumina-rich mullite powder (3Al ₂ O ₃ .2SiO ₂ ) having an average particle diameter of 2 μm, 25.3 parts of quartz powder (SiO ₂ ) having an average particle diameter of 1 μm, and alumina having an average particle diameter of 0.4 μm 1.9 parts of powder (Al ₂ O ₃ ) and magnesium carbonate (Mg ₃ (CO ₃ )) having an average particle size of 0.3 μm
₄ (OH) ₃ .5H ₂ O) is converted into MgO in 0.8 parts, and 5.9 parts of polyvinyl butyral having an average degree of polymerization of 1000 as a resin is put in a ball mill and dry mixed for 3 hours. Furthermore, 1.9 ml of butyl phthalyl glycolate as a plasticizer, and trichloroethylene 46 as a solvent.
Part, tetrachloroethylene 17 parts and n-butyl alcohol 18 parts are added and wet mixed for 20 hours to prepare a slurry.
Next, bubbles are removed from the slurry by vacuum degassing, and the viscosity is adjusted. Next, the slurry is applied to a silicon film-treated polyester film support with a doctor blade to a thickness of 0.23 mm and dried in an oven to prepare a ceramic green sheet. The ceramic green sheet is removed from the siliconized polyester film support, and cut at intervals of 220 mm. The ceramic green sheet thus produced is cut into 200 mm square pieces using the green sheet punch section, and holes for guides are formed. Thereafter, the ceramic green sheet was fixed using the holes for guides, and through holes having a diameter of 0.15 mm were formed at predetermined positions by a punch method.
Further, a conductive paste of tungsten powder: nitrocellulose: ethylcellulose: polyvinylbutyral: trichloroethylene = 100: 3: 1: 2: 23 (weight ratio) is filled in the through holes formed in the ceramic green sheet, and then screen printing is performed. The above-mentioned conductor paste is printed according to a predetermined circuit pattern. 30 of these ceramic green sheets were laminated as shown in FIG.
The layers were laminated under pressure of ３０30 kg / cm ² . Next, the laminated ceramic green sheets are put into a firing furnace and hydrogen 3
The temperature was raised to 1200 ° C. at a rate of 50 ° C./h in a nitrogen atmosphere containing ７7% by volume and a small amount of water vapor to remove a resin component used in producing a ceramic green sheet. After that, the temperature was raised at a heating rate of 100 ° C./h, the maximum temperature was maintained at 1620 ° C. for 1 hour, and the pressureless firing was performed.
Completed a ceramic multilayer wiring circuit board. This mullite multilayer board is about 67% by weight mullite, Al ₂ O ₃
· SiO ₂ 9% and SiO ₂ glass component was about 24%.

After electroless nickel plating and gold plating were applied to the ceramic substrate for a wiring circuit thus produced, the Kovar pin 4 was connected with a gold-indium solder 5 by a usual method using a carbon jig. Further, the semiconductor component 6 was mounted face down with the solder 7 directly connected thereto. In this way, the functional module shown in FIG. 1 was produced.

The coefficient of thermal expansion of the ceramic insulating material used for the ceramic substrate for a wiring circuit is 50 × 10 ⁷ / ° C. (room temperature to
500 ° C.), and the thermal expansion coefficient of tungsten used as the internal wiring conductor material is 45 × 10 ⁷ / ° C. (room temperature to 500 ° C.)
The thermal stress due to the difference in thermal expansion coefficient between the ceramic insulating material and the wiring conductor material did not occur, and no cracks occurred. The through hole pitch is 0.3m
m was also possible. The crystal phase in the ceramic insulating material of the firing method is mullite (3Al ₂ O _3).
· 2SiO ₂₎ and was Al ₂ O ₃ · SiO _2. Since these stable crystal phases have the same value of thermal expansion coefficient, little internal stress is applied. _{Further, Mg 3 (CO 3) 4} (OH) 2 · 5H 3 O was added, Mg in heated
Although it was O, it was confirmed by the X-ray diffraction method and the X-ray microanalyzer that the composite oxide of MgO and other components did not exist in the ceramic insulating material obtained by the firing method.

The tensile strength of the Kovar pin was 4 kg / pin or more, and was sufficiently strong to withstand actual use. Also,
The solder connection part 7 of the semiconductor component 6 did not cause disconnection even after a temperature cycle of -65 ° C. to 150 ° C. for 2000 cycles or more. Thus, the strength was such that a sufficient connection life could be guaranteed even under severe use conditions. This is because
3Al ₂ O ₃ · 2SiO ₂ and Al ₂ O ₃ · thermal expansion coefficient of the SiO ₂ formed of a sintered body is 50 × 10 ~ ⁷ / ℃ a was in a silicon semiconductor for use as a semiconductor component thermal expansion coefficient of 35 × 1
0 to ⁷ / ° C (room temperature to 500 ° C), and gallium-
Thermal expansion coefficient of arsenic semiconductor 65 × 10 to ⁷ / ° C. (room temperature to 50
(0 ° C), the difference in the amount of expansion between the substrate and the semiconductor component when heated is small in a ceramic substrate for wiring circuits that mixes a silicon semiconductor and a gallium-arsenic semiconductor, and thermal stress is not so much applied to the solder joint. Is. In the case of the conventional substrate containing alumina as the main component, the coefficient of thermal expansion of alumina is 75 × 10 to ⁷ / ° C., which is significantly different from the coefficient of thermal expansion of the silicon semiconductor element, which is the main component currently as a semiconductor component. When heated, thermal stress was applied to the solder joints, resulting in early disconnection.

On the other hand, the signal propagation delay time by the internal wiring conductor 2 was 8.1 ns / m. This value corresponds to the relative dielectric constant of the ceramic insulating material being 6.2. In a conventional printed circuit board made of an insulator containing alumina as a main component, the relative dielectric constant of the ceramic insulating material is about 9.5, and the signal propagation delay time is 10.2 ns /.
m, the signal propagation delay time is reduced by about 20% according to the present embodiment.

Example 2 Example 1 was repeated except that the amounts of the ceramic raw material powders were shown in Tables 1 to 3 by weight%.
A ceramic substrate for a wiring circuit was manufactured in the same manner as described above.
The amounts of the alkali metal oxides and alkaline earth metal oxides in Tables 1 to 3 are shown by converting the actually used carbonate or hydroxide into oxides. Using the same method as in Example 1, the functional module shown in FIG. 1 was manufactured. Addition materials other than mullite are used as flux.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

Table 4 shows Al ₂ O ₃ .SiO ₂ of the obtained substrate.
The content of the phase (% by weight) is shown, and Table 5 also shows the content (% by weight) of the glass component of the obtained substrate.

[0048]

[Table 4]

[0049]

[Table 5]

The structure of the obtained substrate is mullite as a main component, and MgO is contained in mullite or Al ₂ O ₃ .S
Solid solution in iO ₂ , the amount of solid solution is 1% or less in terms of raw material MgO. If it exceeds this, another crystal phase is formed, which has a different thermal expansion coefficient from that of the substrate, which is not preferable. Mullite content 70 wt% (Nos. 1 to 7) and 80
FIG. 2 shows the relationship between the amount of SiO _{2 in} the flux and the bending strength for wt% (Nos. 22 to 28). The bending test was a four-point bending method based on JIS. From the figure, it can be seen that as the glass component increases, the bending strength tends to increase rapidly. That is, the amount of mullite 70 wt%
In the case of the above, the bending strength of 180 MPa or more is the composition in which the amount of SiO _{2 in} the flux is more than 80 wt%, and in the case of the amount of mullite of 80 wt%, the amount of SiO _{2 in} the flux is more than 75 wt%. Many compositions.

FIG. 3 is a diagram showing the relationship between the amount of added SiO ₂ and the bending strength. As shown in the figure, the addition of SiO ₂ improves the sinterability of mullite and sharply improves the strength. However, when it exceeds 30%, the strength sharply decreases, so it is not preferable to add it excessively. . In particular, 40
%, The sinterability is reduced and the strength is reduced. SiO
It is thought that the addition of ₂ improves the sinterability of mullite and increases the strength due to the formation of the glass component.

FIG. 4 is a graph showing the relationship between the bending strength and the amount of Al ₂ O ₃ added. As shown in the figure, the addition of Al ₂ O ₃ sharply reduces the strength. Therefore, the added amount of Al ₂ O ₃ is preferably 5% or less.

Next, the amount of mullite is 70 wt% and 80 w
FIG. 5 shows the relationship between the amount of SiO ₂ in the flux and the relative dielectric constant for t%. The measurement of the relative permittivity was constant at 1 MHz. The relative dielectric constant tends to decrease as the amount of SiO ₂ in the flux increases. That is, the mullite amount 8
In the case of 0 wt%, the relative dielectric constant becomes 6.7 or less because
When the SiO ₂ content in the flux is greater than 85 wt%, and when the mullite content is 70 wt%, the relative dielectric constant is smaller than 6.7 even when the SiO ₂ content in the flux is about 50 wt%.

FIG. 6 is a diagram showing the relationship between the relative dielectric constant and the amount of SiO ₂ added. The addition of SiO ₂ significantly reduces the relative dielectric constant. In particular, when the relative dielectric constant rapidly decreases at 15% or more, it is preferable to add more than 15%.

FIG. 7 is a diagram showing the relationship between the firing temperature and the firing shrinkage of each sample. As shown in the figure, the sample of Example 1 has a constant shrinkage rate at a firing temperature of 1580 ° C. or higher,
The amount of MgO is no. 4.1% and CaO content and Na ₂
If the total amount of O is 2.7%, the firing temperature is 140
It varies between 0 and 1700 ° C and does not become constant. This is unfavorable when a large amount is fired in an electric furnace, since the temperature varies depending on the place in the furnace, and even if the composition is the same, different firing shrinkage ratios are obtained, causing variations in products.

FIG. 8 shows the amount of Al ₂ O ₃ added and A produced on the substrate.
FIG. 3 is a diagram showing a relationship with the amount of l ₂ O ₃ · SiO ₂ . As shown in FIG, Al the addition amount of _{Al 2 O 3 2 O 3 ·} SiO 2
Will increase. This Al ₂ O ₃ .SiO ₂ has properties equivalent to mullite.

From these results, a composition having a large bending strength and a small relative dielectric constant has a composition in which the SiO ₂ content in the flux is more than 80 wt% when the mullite content is 70 wt%, and the composition has a mullite content of 80 wt% %, The composition is such that the amount of SiO ₂ in the flux is more than 85 wt%. That is, the composition is 1 wt% or less as alkaline earth metal oxide (MgO).

Next, with respect to the ceramic insulating materials having these compositions, X-ray diffraction was performed to identify the crystal phase in the sintered body. The amount of alkaline earth metal oxide (MgO) is 1
If it is more than wt%, Al ₂ O ₃ .Mg
O and 2Al ₂ O ₃ · 2MgO · 5SiO ₂ are formed, but 3Al is formed at around 1600 ° C, which allows sufficient firing.
_{In addition to 2} O ₃ · ₂ SiO ₂ and Al ₂ O ₃ · SiO ₂ , Al ₂ O ₃ ,
Since there are many crystal phases composed of MgO and SiO _2, they cannot be identified. For this reason, there is a problem that the firing shrinkage ratio at each temperature is not constant, and the variation is large.

On the other hand, alkaline earth metal oxide (MgO)
When the amount is 1 wt% or less, a large amount of SiO ₂ and Al ₂ O ₃ .MgO, 2Al ₂ O ₃ .2Mg added in the firing process.
O · 5SiO ₂ is possible, in 1600 around ℃ capable of performing baking enough, a 3Al ₂ O ₃ · 2SiO ₂ and Al ₂ O ₃ · SiO ₂ only becomes stable crystalline phases. Therefore, at a firing temperature higher than 1550 ° C., that is, at a temperature at which sufficient firing is possible, the crystal phase does not change and the firing shrinkage amount is stable. In addition, Nos. Similar results were obtained for the compositions shown in 29 to 56. That is, when the total amount of the alkali metal oxide and the alkaline earth metal oxide is 1
When it is more than wt%, the bending strength is lower than 180 MPa or the relative dielectric constant is higher than 6.7. Also, the crystal phase after firing is not stable, and 3Al ₂ O ₃ · 2SiO ₂ and Al ₂
An unstable crystal phase was formed in addition to O ₃ · SiO ₂ .

On the other hand, when the total amount of the alkali metal oxide and the alkaline earth metal oxide was 1 wt% or less, the bending strength was 180 MPa or more and the relative dielectric constant was 6.7 or less. Also, the crystalline phase after firing is stable,
At a sintering temperature of not lower than ₃ ° C., 3Al ₂ O ₃ .2SiO ₂ and Al ₂
There were only two types of crystal phases, O ₃ and SiO ₂ . That is, the added alkali metal oxide and alkaline earth metal oxide are 3Al ₂ O ₃ .2SiO ₂ or Al ₂ O ₃ .Si.
Diffusively dissolved in the O ₂ crystal phase.

The coefficient of thermal expansion of the ceramic insulating material having the composition shown in Tables 1 to 3 is 40 to 60 × 10 to ⁷ / ° C. (room temperature to 50).
In the range of 0 ° C.), the thermal expansion coefficient of 45 × 10 ~ ⁷ / ℃ tungsten used for internal wiring conductor material (room temperature to 500
C.), the thermal stress due to the difference in thermal expansion coefficient between the ceramic insulating material and the wiring conductor material was small, and no cracks were observed.

In the composition (Tables 1 to 3) in which the total amount of the alkali metal oxide and the alkaline earth metal oxide is 1% by weight or less, the tensile strength of the Kovar pin is 4 kg / pin or more, which is enough to withstand practical use. Met. Further, the solder connection part of the semiconductor component is 2,000-65 ° C. to 150 ° C.
No disconnection occurred after more than one temperature cycle. The strength was such that a sufficient connection life could be guaranteed even under such severe use conditions. This is because the coefficient of thermal expansion of a silicon semiconductor used as a semiconductor component is 35 × 10 to ⁷
/ ° C (room temperature to 500 ° C), and the coefficient of thermal expansion of the gallium-arsenic semiconductor is 65 × 10 ~ ⁷ / ° C (room temperature to 500 ° C).
This is because even in such a mixed wiring circuit ceramic substrate, the amount of expansion of the substrate and the semiconductor component when heated is small, and stress is not so much applied to the solder connection portion.

On the other hand, the signal propagation delay time due to the internal wiring conductor when the circuit board was multilayered was 8.4 ns / m or less. This value corresponds to the relative dielectric constant of the ceramic insulating material being 6.7 or less. Since the alumina-based ceramic insulating material is about 9.5% and the signal propagation delay time is 10.2 ns / m, according to the present embodiment, the signal propagation delay time is reduced by about 17% or more. Will be.

FIG. 9 is a configuration diagram of a semiconductor device mounting using the substrate manufactured in the first embodiment of the present invention. 11: LSI chip, 12: substrate of the present invention, 13: CCB (solder 350
Up to 400 ° C.), 14: silicon carbide sealing body, 15: printed circuit board, 16: backboard (printed circuit board), 1
7: Solder (250-300 ° C.), 18: Cooling water, 1
9: low-temperature solder (150-200 ° C.).

[0065]

According to the present invention, mullite is used as a main component, silicon dioxide, a composite oxide of aluminum oxide and silicon dioxide in a molar ratio of 1: 0.7 to 1 and an alkaline earth metal oxide. The use of the ceramic substrate contains no cracks due to the difference in the coefficient of thermal expansion between the ceramic insulating material and the wiring conductor material, and also causes cracks in the substrate caused by thermal stress and disconnection of the connection between the substrate and the semiconductor component. And the like, and a high-quality and highly reliable ceramic substrate for a wiring circuit can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a wiring circuit ceramic substrate and an insulating module using the same, showing an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the amount of SiO ₂ in the flux and the bending strength.

FIG. 3 is a diagram showing the relationship between bending strength and the amounts of SiO ₂ and Al ₂ O ₃ , respectively.

FIG. 4 is a diagram showing the relationship between the bending strength and the amounts of SiO ₂ and Al ₂ O ₃ .

FIG. 5 is a graph showing the relationship between the amount of SiO ₂ in the flux and the relative dielectric constant.

FIG. 6 is a diagram showing the relationship between the relative dielectric constant and the amount of SiO ₂ .

FIG. 7 is a diagram showing the relationship between firing temperature and firing shrinkage.

8 is a graph showing the relationship between the Al ₂ O ₃ · SiO ₂ amount and the amount of Al ₂ O _3.

FIG. 9 is a configuration diagram showing an example of a mounting structure of a semiconductor device using the substrate of the present invention.

[Explanation of symbols]

1. Ceramic insulating material of the present invention 2. Wiring conductor material
3. Ceramic substrate for wiring circuit of the present invention, 4. Kovar pin, 5. Gold-indium brazing, 6. Semiconductor component, 7.
Solder.

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[Procedure amendment]

[Submission date] December 13, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Shinohara 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi Ltd. Production Engineering Research Laboratory, Hitachi, Ltd.

Claims (2)

[Claims] 1. A glass component 1 containing 67% by weight or more of mullite.
A base made of a ceramic sintered body containing 5 to 30% by weight and 4.3% by weight or more of a composite oxide in which the molar ratio of aluminum oxide and silicon dioxide is 1: 0.7 to 1, and formed on the base. And a conductive material layer that has been formed. 2. The ceramic sintered body according to claim 1, wherein at least one of an alkaline earth metal oxide and an alkali metal oxide is contained in an amount of 1% by weight or less in terms of oxide. A method of manufacturing a ceramic substrate for a wiring circuit.