JPH1153940A - Copper metalized composition and glass ceramic wiring board using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper metalized composition and a glass ceramic wiring board using it which is capable of simultaneously burning a copper metalized composition filled in a via hole and a glass ceramic porcelain, and capable of effectively controlling an obtained via hole conductor to be protruded into protruded shape from an insulation base body surface, consisting of a glass ceramic porcelain, and particularly suitable in various circuit boards or high-frequency multilayered wiring boards or the like having a thermal via. SOLUTION: A copper metalized composition for a via hole containing 2 to 20 wt.% of SiO2 -Al2 O3 - RO (R: an alkaline earth metal) -B2 O3 based glass flit of 700 to 750 deg.C in glass transition point with respect to 100 wt.% of a main component, copper powders, is used and burned at the same time together with a glass ceramic porcelain at 700 to 1000 deg.C. Thereby, a glass ceramic wiring board of 5 μm or less in protrusion height from an insulation base body surface of a via hole conductor is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper metallized composition for via holes which can be fired simultaneously with glass ceramic porcelain, and an insulating substrate made of glass glass porcelain which is fired simultaneously with glass ceramic porcelain. Circuit board and high-frequency multilayer wiring with low-resistance via-hole conductors suitable as thermal vias, in which the height of the formed via-hole conductors from the surface of the insulating substrate is extremely small due to good consistency of firing shrinkage. The present invention relates to a glass ceramic wiring substrate applied to a substrate or the like.

[0002]

2. Description of the Related Art Conventionally, as an insulating base for various kinds of wiring boards such as a semiconductor element housing package for housing a semiconductor element and a hybrid integrated circuit device mounted with various electronic components in addition to the semiconductor element, an electric insulating property and a chemical insulating property are known. Alumina ceramics having excellent properties such as mechanical stability have been widely used.

However, in recent years, wiring boards frequently used in the high frequency range of 1 to 10 GHz in the communication field typified by mobile phones have been further reduced in conductor loss and reduced in size compared to the insulating base made of alumina ceramics. Therefore, copper (Cu) or gold (A) is used as a low-resistance conductor.
u), a glass-ceramic wiring substrate having a wiring layer formed of silver (Ag) and having a dielectric constant similar to that of alumina ceramics has been attracting attention as a wiring substrate for the communication field.
Application to power amplifier modules and the like of mobile phones is being studied.

On the other hand, the glass ceramic has a problem that heat conductivity is lower than that of alumina ceramic and heat radiation generated by a semiconductor element contained therein is inferior. Form a via hole from the die attach part to be mounted to the back surface of the insulating substrate, fill the via hole with a conductive material having high thermal conductivity to form a thermal via, and efficiently transfer heat through the conductive material having high thermal conductivity of the thermal via. Measures such as radiation are taken.

[0005] As the conductive material having such a high thermal conductivity, copper, gold, and silver of the low-resistance conductor can be applied,
Gold has the disadvantage of being expensive.

On the other hand, silver can be baked in the air, and wire bonding can be performed without plating on the wiring conductor formed on the surface of the insulating substrate. Although this is advantageous in terms of cost, the silver wiring conductor can be used. There is a disadvantage that the reliability is inferior from the problem of migration and solder erosion, and when palladium or the like is added to silver to improve it, the conductor resistance becomes high, especially for a wiring board used in the high frequency region. Was not applicable.

Accordingly, the low-resistance conductive material must be fired in a non-oxidizing atmosphere, and the wiring conductor on the surface of the insulating substrate requires plating, but high reliability can be ensured. Research and development are being carried out diligently.

A glass ceramic wiring board using copper as a wiring conductor is formed, for example, by forming a slurry prepared by using glass ceramic raw material powder and an organic binder into a sheet, and then forming a via hole or the like in the obtained glass ceramic green sheet. Punching, filling the via holes with a conductive paste containing copper as a main component, forming a predetermined wiring pattern on the green sheet using the same conductive paste, and aligning a plurality of these sheets. After lamination under pressure, it has been generally manufactured by heating the laminate in a non-oxidizing atmosphere consisting of a nitrogen atmosphere containing water vapor to remove the binder and fire it.

On the other hand, the thermal via can be formed simultaneously in the same manner as a normal via hole, and the conductor paste for the via hole is punched into an opening of a glass ceramic green sheet where a semiconductor element is mounted. It is formed by filling and firing.

However, in general, the insulating base of the glass-ceramic wiring board and the via-hole conductor made of copper have different firing shrinkage rates. That is, spherical copper powder is used for the copper conductor paste forming the via-hole conductor. Since the filling property of the copper powder is high and the firing shrinkage rate is low, or the firing start temperature of the copper conductor paste is lower than that of the glass ceramic green sheet, the firing shrinkage curves of both tend to be inconsistent, and firing shrinkage tends to occur. It is difficult to make the ratios match exactly, and the via-hole conductor often protrudes from the surface of the insulating substrate due to the difference in shrinkage behavior between the two.

Therefore, particularly when the via-hole conductor forms a thermal via, if the via-hole conductor protrudes in a convex shape, a connection failure occurs when the semiconductor element is mounted on the surface of the insulating base, or the semiconductor element is inclined. Therefore, there is a disadvantage that the wire bonding becomes difficult, and when the semiconductor element is pressed down and mounted on the surface of the insulating base, the semiconductor element itself is broken.

In order to solve the above-mentioned drawback caused by the via-hole conductor in the bonding pad portion projecting in a convex shape, a via-hole electrically connected to the die-attach portion by removing the die-attach portion on which the semiconductor element is mounted. It has been proposed to provide a conductor (JP-A-5-13)
No. 6285).

[0013]

However, in the above proposal, since the via-hole conductor is provided at a position distant from the die attach portion, a thermal via for dissipating heat generated in the housed semiconductor element is provided directly below the semiconductor element. It is difficult to efficiently dissipate the heat because it is not disposed in a semiconductor device. There was a problem that was.

[0014]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a method for simultaneously firing a copper metallized composition filled in a via hole and glass ceramic porcelain. The conductor can effectively control that the conductor protrudes from the surface of the insulating substrate made of glass ceramic porcelain, and is particularly suitable for a copper metallized composition and a copper metallized composition suitable for various circuit boards having thermal vias or high-frequency multilayer wiring boards. To provide a glass ceramic wiring board.

[0015]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies, and as a result, have found that SiO ₂ —Al
_{By including 2} O ₃ -RO (R: alkaline earth metal) -B ₂ O ₃ -based glass frit in the copper metallized composition, the copper metallized composition filled in the via hole and the glass ceramic porcelain are simultaneously fired. However, it has been found that the obtained via-hole conductor can reduce the protrusion from the surface of the insulating substrate made of glass ceramic porcelain.

That is, the copper metallized composition of the present invention comprises:
A copper metallized composition for via holes that can be co-fired with glass ceramic porcelain at a temperature of 00 to 1000 ° C,
The composition has a SiO ₂ —Al ₂ O ₃ —R having a glass transition point of 700 to 750 ° C. based on 100 parts by weight of a copper powder as a main component.
O: and it is characterized in that it contains 2 to 20 parts by weight of (R alkaline earth metal) -B ₂ O ₃ based glass frit.

In particular, the borosilicate glass frit preferably has a glass transition point of 720 to 750 ° C. and a content of 3 to 15 parts by weight with respect to 100 parts by weight of the main component copper powder. It is.

The glass-ceramic wiring substrate using the copper metallized composition of the present invention has a glass transition point of 700.
To 750 ° C. of SiO ₂ -Al ₂ O ₃ -RO: the (R alkaline earth metal) -B ₂ O ₃ based glass frit and containing 2 to 20 parts by weight with respect to the copper powder 100 parts by weight of the main component of copper The metallized composition is placed in a nitrogen atmosphere at 700 to 1000
A via-hole conductor formed by co-firing with a glass ceramic porcelain at a temperature of ° C., wherein the height of the via-hole conductor protruding from the surface of an insulating substrate made of glass ceramic porcelain is 5 μm or less. .

In particular, the borosilicate glass frit in the copper metallized composition has a glass transition point of 720 to 720.
More preferably, the content is 750 ° C., and the content is 3 to 15 parts by weight based on 100 parts by weight of the copper powder as the main component.

Further, the via-hole conductor of the glass ceramic wiring board using the copper metallized composition is most suitable as a thermal via.

[0021]

According to the present invention, a copper metallized composition for a via hole is made of SiO ₂ having a glass transition point of 700 to 750 ° C.
—Al ₂ O ₃ —RO (R: alkaline earth metal) —B ₂ O
700 to 10 because it contains ₃ series glass frit
The glass frit and the glass ceramic porcelain can be co-fired at the above-mentioned temperature because they can be co-fired with the glass ceramic porcelain at a temperature of 00 ° C. and can match the firing shrinkage behavior with the insulating substrate made of the glass ceramic porcelain. With the reaction, the glass component in the copper metallized composition and the glass ceramic porcelain of the insulating substrate interdiffuse, and the shrinkage of the copper metallized composition filled in the via hole is promoted. It is possible to obtain a glass-ceramic wiring board in which the protrusion of the conductor is extremely small.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the copper metallized composition of the present invention and a glass ceramic wiring board using the same will be described in detail.

The copper metallized composition of the present invention has a glass transition point of 700 to 750 ° C. as a glass frit containing copper as a main component and interdiffusing with glass ceramic porcelain.
SiO ₂ —Al ₂ O ₃ —RO (R: alkaline earth metal) —B ₂ O ₃ based glass whose content accounts for 2 to 20 parts by weight based on 100 parts by weight of the main component .

As the main component copper in the copper metallized composition of the present invention, it is more preferable to use spherical powder having an average particle size of 1 to 10 μm, more preferably 2 to 6 μm.

The specific surface area of the copper powder is 0.2 to 0.2.
Is about 1.5 m ² / g, when the shape of the copper powder is non-spherical, for example, when a dendritic powder prepared by electrolytic method, packing density of the copper powder in the copper conductor paste is lowered In addition, there is a problem that coarse voids are easily generated inside the via-hole conductor after firing.

Further, ceramic powder can be added to the copper conductor paste in order to finely adjust the shrinkage behavior of the glass in the paste due to softening flow, and the copper powder has a high melting point. Any compound may be used as long as it does not easily react to form a compound, and examples thereof include Al ₂ O ₃ , SiO ₂ , and ZrO ₂ .

The amount of the ceramic powder to be added depends on the particle size and the glass powder added to the copper conductor paste, but is preferably about 0.5 to 3 parts by weight per 100 parts by weight of the copper powder. If it is too much, the via-hole conductor cannot be sintered densely, and the protrusion of the via-hole conductor becomes large.

On the other hand, the organic binder used for the copper conductor paste is an acrylic resin, preferably a methacrylic acid resin, having excellent thermal decomposability in a non-oxidizing atmosphere, and the solvent is dibutyl phthalate or the like. A general conductive paste solvent such as α-terpineol can be used.

The firing of the glass ceramic porcelain having the wiring pattern formed by using the copper conductor paste is performed as follows.
Generally, it is carried out in a nitrogen atmosphere mixed with water vapor. However, in order to react a small amount of carbon remaining after decomposition of the organic binder with water vapor in the atmosphere and to remove the carbon efficiently, the firing shrinkage temperature of the glass ceramic porcelain is set to 700. ° C. or higher, it is desirable to perform the decarbonization treatment in a porous state before the glass ceramic porcelain starts shrinkage shrinkage. It is desirable to be as high as possible.

Next, the glass frit in the present invention is a borosilicate glass frit represented by SiO ₂ —Al ₂ O ₃ —RO (R: alkaline earth metal) —B ₂ O _3. Has a feature that it is easy to increase the glass transition point to 700 ° C. or higher, and rapidly softens and flows at a temperature equal to or higher than the transition point.

[0031] In the borosilicate glass represented by Pyrex glass (SiO ₂ -B ₂ O ₃ system), the SiO ₂ -Al ₂ O ₃ -RO by increasing the amount of SiO ₂
There is not possible to have: (R alkaline earth metal) -B ₂ O ₃ system glass and similar glass softening point, but the glass transition point as low as 600 ° C. or less, and gradual decrease of the glass viscosity versus temperature Therefore, it is very difficult to match the shrinkage curve of the copper metallized composition to which the borosilicate glass is added with the shrinkage curve of the glass ceramic porcelain.

When the glass transition point is increased by adjusting the composition of the borosilicate glass, the firing temperature (700 to 10
(00 ° C.), the fluidity of the glass is poor, and the copper metallized composition cannot be sintered densely.

On the other hand, the copper powder as the main component in the copper metallized composition of the present invention depends on its particle size distribution and shape.
Generally, the firing shrinkage starts at about 500 ° C., so that the shrinkage starting temperature of the copper metallized composition is increased, and the simultaneous firing temperature with the glass ceramic porcelain (700 to 1000).
(C), it is effective to add a glass powder having a high glass transition point to obtain a dense structure.

That is, it is necessary to add a glass powder which is in a solid state at a low temperature below the glass transition point, becomes a liquid phase above the glass transition point and rapidly softens and flows into the copper metallized composition. Yes, the expression of glass softening point is often used to express the softening properties of glass,
Even if the glasses have the same softening point, the change in the glass viscosity with respect to the temperature greatly varies depending on the glass composition system. Therefore, the selection of the glass composition system is important.

Therefore, in the present invention, when the glass transition point of the borosilicate glass frit is lower than 700 ° C., the shrinkage of the via-hole conductor during firing proceeds at a lower temperature than that of the glass ceramic porcelain. The via hole conductor has a large protrusion height, and the glass transition point is 75
If the temperature exceeds 0 ° C., the softening flow of the glass during firing becomes insufficient, so that densification failure of the via-hole conductor occurs. Therefore, the entire via-hole conductor protrudes in a convex shape, and the resistance value of the via-hole conductor also increases.

In particular, for high frequency applications to which the wiring board of the present invention is applied, it is necessary that at least the above-mentioned resistance value is about 5 mΩ / mm or less.

Next, when the content of the borosilicate glass frit is less than 2 parts by weight based on 100 parts by weight of the copper powder as the main component, the effect of suppressing sintering of the copper powder is small, and the surface of the insulating substrate of the via-hole conductor is reduced. The height of the protrusion from the substrate becomes large, and if it exceeds 20 parts by weight, the resistance value of the via-hole conductor becomes high. Therefore, the content is limited to 2 to 20 parts by weight, and further, the glass transition point is 720 to 750 ° C. Its content is 3 to 15
More preferably, it is by weight.

On the other hand, the glass ceramic porcelain of the present invention is composed of a mixture of a borosilicate glass containing SiO ₂ and B ₂ O ₃ and a ceramic filler, and the borosilicate glass has a glass transition point of 700 to 800 ° C. S
iO ₂ —Al ₂ O ₃ —RO (R: alkaline earth metal, Z
n) -B are ₂ O ₃ based crystalline glass, the average particle diameter is preferably that of 1 to 5 [mu] m.

If the glass transition point is lower than 700 ° C., shrinkage of the glass ceramic porcelain starts at a low temperature, so that it is difficult to sufficiently remove the binder in a non-oxidizing atmosphere. Powder production becomes difficult and the firing temperature becomes high, which is not suitable.

On the other hand, the ceramic filler mixed with the borosilicate glass can be selected according to the required material properties. For example, Al ₂ O ₃ , SiO ₂ , ZrO ₂ , 3Al ₂
O ₃ · 2SiO _2, calcium zirconate, include strontium titanate, an average particle diameter of from 0.5 to 3
μm is desirable.

Further, since the glass ceramic porcelain forming the copper wiring conductor is debindered in a non-oxidizing atmosphere such as nitrogen, the organic binder to be used is preferably a methacrylic acid resin or the like which is excellent in thermal decomposability. It is also possible to add a plasticizer according to the properties of the organic binder.

In the glass ceramic wiring board thus obtained, when the height of the via-hole conductor projecting from the surface of the insulating substrate exceeds 5 μm, the efficiency of heat dissipation from the connected semiconductor element is deteriorated, and the electric power of the semiconductor element is reduced. This is unsuitable because the characteristics may not be stable.

In the simultaneous sintering of the copper metallized composition of the present invention and the glass ceramic porcelain, the organic binder, plasticizer, solvent and the like contained therein were decomposed and removed in a nitrogen atmosphere containing water vapor at 300 to 500 ° C. Thereafter, the temperature is increased to 700 to 1000 ° C. in a nitrogen atmosphere containing water vapor.
, And a small amount of carbon remaining in the glass ceramic porcelain is removed by reacting with water vapor, and the glass ceramic porcelain is densified. When crystalline glass is used, the glass is crystallized simultaneously with the densification.

Next, the obtained copper wiring conductor on the surface of the insulating substrate is subjected to plating according to the intended use, the base is coated with nickel or copper, and gold is coated thereon to have a copper wiring conductor. A glass ceramic wiring board is obtained.

[0045]

EXAMPLE The copper metallized composition of the present invention and a glass ceramic wiring board using the same were evaluated as follows based on one example.

First, SiO ₂ —Al ₂ O ₃ —RO having a glass transition point (Tg) having a composition shown in Table 1 different from the main component of the copper metallized composition having an average particle size of 5 μm.
The: (R alkaline earth metal) -B ₂ O ₃ based glass frit and Al ₂ O ₃ powder as filler, copper powder 1 of the main component
The components were mixed in the proportions shown in Table 2 with respect to 00 parts by weight,
An organic binder and a solvent were added to the mixture and kneaded to prepare a copper metallized sample for a paste-like via-hole conductor.

[0047]

[Table 1]

On the other hand, 44% by weight of SiO ₂ and Al ₂ O ₃
There 28 wt%, MgO 11 wt%, ZnO 8% by weight, B ₂ O ₃ is 9% by weight of a crystalline glass powder 61 wt% with the composition, powdered calcium 21 wt% zirconate, strontium titanate powder 16% by weight, Al ₂ O
_{(3) To a} glass ceramic raw material powder composed of 2% by weight of powder, 12% by weight of solid content of isobutyl methacrylate resin as an organic binder and 6% by weight of dibutyl phthalate as a plasticizer, and toluene and ethyl acetate as solvents are added. The mixture was mixed by a ball mill for 40 hours to prepare a slurry.

A glass ceramic green sheet having a thickness of 0.4 mm was formed from the obtained slurry by a doctor blade method, a via hole having a diameter of 0.12 mm was formed in the green sheet, and the copper paste for via hole conductor was filled in the via hole. It was filled, and a pad pattern was printed on the upper surface thereof to produce a molded body in which three sheets were laminated under pressure.

Then, in order to remove the organic components such as the organic binder in the molded body and the carbon remaining after the organic components are decomposed, in a nitrogen atmosphere containing 55 mmHg of steam at a temperature of 750 ° C. for one hour. After performing the heat treatment for holding, the glass ceramic wiring board for evaluation was manufactured by holding at 900 ° C. for 1 hour.

Using the glass ceramic wiring board for evaluation, the protruding height (μ) was measured by a stylus method using a surface roughness meter so as to cross the via-hole conductor on the surface of the insulating substrate.
m), the resistance of the via-hole conductor penetrating the insulating substrate was measured by a four-terminal method, and the via-hole resistance (m
Ω / mm).

After the surface of the semiconductor element is mounted on the via-hole conductor, the semiconductor element is ground and removed, and the ratio of the bonding area to the die-attach portion is examined.
Those with less than 90% were determined to be defective, and their suitability for thermal vias was judged from their bonding properties.

Based on the individual evaluations described above, comprehensive evaluations were made for excellent, good, and poor.

[0054]

[Table 2]

As is clear from the table, in Sample Nos. 1, 2, 6, and 7, which are out of the claims of the present invention, the protrusion height of the via hole is 7 μm or more, and the bonding property as a thermal via is poor. Similarly, in sample numbers 6 and 14, the via-hole conductor had an extremely large resistance of 5.5 mΩ / mm or more,
The object of the present invention is not satisfied.

On the other hand, in the wiring boards according to the present invention, the projecting height of the via-hole conductor is less than 5 μm, the resistance is as low as 4.7 mΩ / mm or less, and the wiring board is suitable for thermal via.

The present invention is not limited to the above-described embodiment.

[0058]

As described in detail above, the copper metallized composition of the present invention and the glass ceramic wiring board using the same have a glass transition point of 700 to 750 ° C. with respect to 100 parts by weight of the main component copper powder. SiO ₂ —Al ₂ O ₃ —RO
(R: alkaline earth metal) -B ₂ containing O ₃ based 2-20 parts by weight of glass frit, since produced using a copper metallization composition for glass ceramic porcelain and fireable via holes, copper metallization As the glass frit in the composition reacts with the glass ceramic porcelain of the insulating substrate, the shrinkage of the copper metallized composition is promoted, and the protrusion of the via-hole conductor on the surface of the insulating substrate composed of the glass ceramic porcelain becomes extremely small. A suitable glass ceramic wiring board can be obtained.

Claims (5)

[Claims] 1. A copper metallizing composition for via holes which can be co-fired with glass ceramic porcelain, having a glass transition point of 700 to 75 with respect to 100 parts by weight of copper powder as a main component.
A copper metallized composition comprising 2 to 20 parts by weight of 0 ° C. SiO ₂ —Al ₂ O ₃ —RO (R: alkaline earth metal) —B ₂ O ₃ based glass frit. _2. An SiO ₂ —Al ₂ O having a glass transition point of 720 to 750 ° C. with respect to 100 parts by weight of the copper powder as the main component.
₃ -RO (R: alkaline earth metal) -B ₂ O ₃ based copper metallization composition of claim 1, wherein the glass frit is characterized by containing 3-15 parts by weight. 3. SiO ₂ —Al ₂ O ₃ — having a glass transition point of 700 to 750 ° C. based on 100 parts by weight of copper powder as a main component.
The (alkaline earth metal R) -B ₂ O ₃ based copper metallization composition and the glass frit contains 2-20 parts by weight, RO
A glass-ceramic wiring board having a via-hole conductor formed by co-firing with a glass-ceramic porcelain at a temperature of 700 to 1000 ° C. in a nitrogen atmosphere, wherein the height of the via-hole conductor protruding from the surface of the insulating base made of the glass-ceramic porcelain Is 5 μm or less. 4. The SiO ₂ -A in said copper metallized composition
l ₂ O ₃ -RO (R: alkaline earth metal) -B ₂ O ₃ based glass transition point of the glass frit is 720-750 ° C., 3 the content of the copper powder 100 parts by weight of the main component The glass-ceramic wiring board according to claim 3, wherein the amount is from 15 to 15 parts by weight. 5. The glass ceramic wiring board according to claim 3, wherein said via hole conductor forms a thermal via.