JP2002261445A - Wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board which can solve the problem raised when wiring having a thickness of >=30 μm is formed by simultaneously baking the wiring with an insulating substrate that the substrate warps, the resistance of the substrate increases, and disconnection, etc., is caused by the cracking or peeling of the wiring. SOLUTION: This wiring board is provided with the insulating substrate 1 composed of an AlN sintered compact containing AlN as the main ingredient and sintering aids and a wiring conductor layer 4 having a thickness of >=30 μm on or in the substrate 1. The conductor layer 4 contains a metallic component composed mainly of at least one kind of metal selected out of molybdenum and tungsten and a ceramic component in an amount of 5-15 wt.% per 100 wt.% of the metallic component. The ceramic component contains AlN and sintering aids and the ratio of the content of the sintering aids to that of AlN in the wiring conductor layer 4 is made 3-6 times as high as that of the content of the sintering aids to that of the metallic component in the AlN sintered compact.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AlN-type wiring board applied to various wiring boards and packages for housing semiconductor elements, and more particularly to a wiring conductor capable of flowing a large current, such as a power module board. The present invention relates to a wiring board having a layer and excellent heat dissipation.

[0002]

2. Description of the Related Art In recent years, heat generation from a semiconductor device has tended to increase with the increase in the degree of integration of semiconductor elements. In order to eliminate the malfunction of the semiconductor device caused by this, substrate materials having excellent heat dissipation properties have been required. Have been. Further, as for the power module substrate and the like, there is a demand for a wiring substrate capable of handling a large current of wiring and having excellent heat dissipation as described above.

Conventionally, alumina-based sintered bodies have been used for various insulating substrates and packages for accommodating semiconductor elements. However, their thermal conductivity is as low as about 20 W / m · K. Instead, AlN sintered bodies having high thermal conductivity have been attracting attention.

Since the theoretical thermal conductivity of this AlN has a high value of 320 W / m · K, research and development of a sintered body for approaching the theoretical value has been advanced, and recently 200 W / m · K has been promoted. An AlN sintered body having a thermal conductivity of K can be manufactured.

In a wiring substrate using an AlN sintered body as an insulating substrate, a wiring conductor layer is formed of a high melting point metal such as W or Mo, and is formed by simultaneous firing with the insulating substrate.

[0006]

However, as described above, the volume resistivity of the insulating substrate made of the AlN sintered body and the ordinary wiring conductor layer formed by co-firing are 3 × 10 5
^Since it is so high as ⁻⁸ Ω · cm, it cannot cope with a conductor layer for flowing a large current of 1 A or more, and therefore, it has been proposed to increase the thickness of the wiring conductor layer.

However, when the thickness of the wiring conductor layer is increased, the wiring conductor layer itself tends to cause poor sintering, and the periphery of the thick wiring conductor layer of the insulating substrate also suffers from poor sintering. Disconnection occurs due to the increase in resistance of the wiring conductor layer and the separation of the interface between the wiring conductor layer and the insulating substrate.
Since the shrinkage behaviors of the wiring conductor layer and the insulating substrate are different, there is a problem that the wiring substrate is warped.

Therefore, according to the present invention, when the thickness of the wiring conductor layer is 3
Even when the thickness is as thick as 0 μm or more, it can be formed by co-firing with an insulating substrate, does not cause the above problems due to poor sintering, has a small warpage of the substrate, and has a wiring conductor layer capable of handling a large current. It is an object of the present invention to provide an AlN-based wiring board.

[0009]

The present inventors have conducted various studies on the above-mentioned phenomena. As a result, it has been found that in the case of a thick wiring conductor layer, sintering failure is likely to occur due to a large absolute volume. Also, in the initial stage of sintering, the wiring conductor layer in a porous state
In order to absorb the sintering aid in the surrounding insulating substrate,
In order to find out the occurrence of sintering failure of the sintered body around the wiring conductor layer and eliminate it, the wiring conductor layer contains AlN, which is the same component as that of the insulating substrate, and is added thereto. It has been found that the above sintering failure is eliminated by blending the sintering aid in a much larger amount than the AlN sintered body.

That is, the wiring board of the present invention comprises an insulating substrate of an AlN sintered body containing a main component composed of AlN and a sintering aid component, and having a thickness of 30 mm on the surface or inside of the insulating substrate.
A wiring substrate comprising a wiring conductor layer having a thickness of at least one of molybdenum and tungsten.
5 to 15 parts by weight of a ceramic component with respect to parts by weight, wherein the ceramic component contains AlN and a sintering aid component, and contains the sintering aid with respect to AlN in the wiring conductor layer. The amount is 3 to 6 times the content of the sintering aid to AlN in the AlN sintered body.

[0011] As a sintering aid component in the AlN sintered body, at least one of Y-containing rare earth elements and / or at least one of alkaline earth elements are converted to oxides in total of AlN100. 2 per part by weight
Desirably, the content is 20 parts by weight.

Further, as a sintering aid component in the wiring conductor layer, at least one of Y-containing rare earth elements and / or
Alternatively, at least one of the alkaline earth elements is 10 to 70 per 100 parts by weight of AlN in total in terms of oxide.
It is desirable to include them in parts by weight. Further, the Al
It is desirable that the same element as the rare earth element and / or the alkaline earth element contained as the sintering aid component in the N-type sintered body be contained in the wiring conductor layer.

According to the present invention, the amount of the sintering aid in the AlN-containing ceramic component contained in the wiring conductor layer having a size of 30 μm or more is 3 times the amount of the sintering aid in the AlN sintered body constituting the insulating substrate. By setting it to 6 times, at the initial stage of sintering, the wiring conductor layer does not absorb the sintering aid component in the surrounding AlN molded body, and the sinterability of the wiring conductor layer can be improved. As a result, the thick wiring conductor layer and the surrounding AlN sintered body are sintered together to increase the resistance of the wiring conductor layer, prevent disconnection due to separation of the interface between the wiring conductor layer and the insulating substrate, and reduce the wiring. The occurrence of warpage on the surface of the substrate or the wiring conductor layer can be prevented.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Overall Structure) Hereinafter, a description will be given based on a schematic sectional view showing one embodiment of a wiring board of the present invention.
The wiring board of FIG. 1 includes an insulating substrate 1 on which a plurality of insulating layers 1a, 1b, and 1c made of an AlN sintered body are stacked.
Each surface of the insulating layers 1a, 1b, 1c has a thickness of 30 μm.
Less than the general conductor layer 2 is provided. Further, the insulating layer 1a as the outermost layer and the insulating layer 1b as the intermediate layer have a thickness of 3
The wiring conductor layer 4 having a thickness of 0 μm is provided. In addition, the general conductor layers 2 or between the general conductor layer 2 and the wiring conductor layer 4 are appropriately electrically connected by via-hole conductors 3.

The wiring conductor layer 4 provided on the insulating layer 1a, which is the outermost layer, has a function as a heat sink for radiating heat generated by components mounted on the surface of the wiring board, in addition to the wiring for large current. Have. In addition, the above-mentioned general conductor layer 2,
Each of the wiring conductor layer 4 and the via-hole conductor 3 is made of a conductor containing tungsten (W) and / or molybdenum (Mo) as a main component, and is formed by simultaneous firing with the insulating substrate 1. .

In the present invention, A which constitutes the insulating substrate 1
The 1N sintered body contains AlN as a main component, and as a sintering aid component, at least one of rare earth elements including Y and / or at least one of alkaline earth elements in total in terms of oxide. 2-2 per 100 parts by weight of AlN
It is desirably contained in an amount of 0 parts by weight, particularly 5 to 15 parts by weight.

If the amount of the auxiliary agent is less than 2 parts by weight, sintering cannot be performed unless the sintering temperature is 1900 ° C. or more. Becomes difficult. If the amount is more than 20 parts by weight, the thermal conductivity, which is an advantage of the AlN-based sintered body, is significantly reduced.

The rare earth elements containing Y include Y, Er,
At least one selected from the group consisting of Yb, Lu, Sm, and Lu
Seeds are preferably used. As the alkaline earth element, at least one selected from the group consisting of Ca, Ba, and Sr is suitably used.

In order to further improve the sinterability at a low temperature of 1700 ° C. or less, it is desirable to use the rare earth element containing Y and the alkaline earth element together, in which case the rare earth element containing Y 2 parts by weight or more in terms of oxide,
In particular, it is desirable to contain 4 parts by weight or more and an alkaline earth element in a proportion of 0.02 parts by weight or more, particularly 0.05 parts by weight or more in terms of oxide.

In order to improve other characteristics of the AlN sintered body, a 4a group such as Ti, Ta,
Group 5a group element such as Cr, group 6a group such as W and Mo, group 7a group such as Mn, and group 8a group element such as Fe, Ni and Co are contained in a ratio of 3 parts by weight or less in terms of oxide. Is also good.

In order to achieve the high thermal conductivity of the insulating substrate 1, it is preferable that the content of the sintering aid component is small, and the insulating substrate 1 is composed of a dense body having a relative density of 95% or more, particularly 97% or more. Is desirable.

Further, it is desirable that the thermal conductivity of the AlN sintered body is close to the theoretical value.
Further, it is 100 W / m · K or more, and further, 120 W / m.
-It is desirable to be K or more.

According to the present invention, among the various conductor layers provided on the wiring board, the wiring conductor layer 4 through which a large current flows has a large thickness, so that sintering failure or the like occurs, and the wiring board is warped. And so on.

Therefore, according to the present invention, the wiring conductor layer 4 is formed of at least one of molybdenum and tungsten.
The seed is used as the main metal component. First, it is important that the ceramic component containing AlN is contained in a proportion of 5 to 15 parts by weight, particularly 5 to 12 parts by weight, based on 100 parts by weight of the metal component. is there.

This prevents sintering failure of the wiring conductor layer 4,
This is for achieving simultaneous sintering with the insulating substrate 1 and reducing the warpage of the wiring substrate. If the content of the ceramic component is less than 5 parts by weight, the difference in the shrinkage behavior from the insulating substrate 1 becomes large, and the warpage of the wiring board increases. On the other hand, if the amount is more than 15 parts by weight, the conduction resistance of the wiring conductor layer 4 becomes high, which makes it unsuitable for applying a large current.

The ceramic component includes a sintering aid component composed of a compound containing at least one of a rare earth element containing Y and / or an alkaline earth element in addition to AlN. It is important that the content of the sintering aid component with respect to AlN is 3 to 6 times, particularly 3 to 5 times, the content of the sintering aid component with respect to AlN in the AlN-based sintered body. That is, when the content is less than three times, the sintering aid component in the AlN molded body of the insulating substrate is transferred to and absorbed by the wiring conductor layer during sintering of the wiring conductor layer. Since the peripheral sintered body causes sintering failure, the bonding strength with the insulating substrate is lost, and there is a possibility that disconnection or the like due to peeling may occur. Also, 6
If it is more than twice, the ceramic component composition in the wiring conductor layer becomes A
Since the composition ratio is largely different from the composition ratio of the 1N sintered body, the difference in shrinkage behavior between the substrate and the wiring conductor layer becomes large, and there is a problem that the substrate and the wiring conductor layer warp.

It is to be noted that at least one of the rare earth elements containing Y and / or at least one of the alkaline earth elements in the wiring conductor layer 4 has a total of 100 parts by weight of AlN in terms of oxide in the above ratio. 10
Suitably, it is contained in a proportion of 70 parts by weight.

The wiring conductor layer 4 contains Ni, in order to adjust the growth of W and Mo particles and to adjust the shrinkage.
O, Fe ₂ O _{3 and the} like may be contained in some cases. However, if the content of these components is too large, significant particle growth occurs,
On the contrary, the content is desirably not more than 2 parts by weight because the resistance may be increased.

Further, in the wiring board of the present invention, the general conductor layer 2 and the via-hole conductor 3 are not particularly limited since they have better sinterability than the thick wiring conductor layer 4. It is desirable in the manufacturing process that the wiring conductor layer 4 is formed of a conductor component having the same composition.

(Manufacturing Method) Next, a method for manufacturing the wiring board of the present invention will be described in detail. First, with respect to 100 parts by weight of AlN powder, at least one compound of the rare earth elements containing Y and at least one compound of the alkaline earth elements are expressed as oxides in a total amount of 100 parts by weight of AlN, It is added in a proportion of 2 to 20 parts by weight, especially 5 to 15 parts by weight. Further, if necessary, Ti, V, Nb, W, M
o, Mn, Fe, Ni, Co, etc.
At least one metal or compound of a, 6a, 7a, or 8a group is added at a ratio of 3 parts by weight or less in terms of oxide.

A slurry is prepared from the above mixture using a binder and an organic solvent, and the slurry is formed into a sheet by a method such as a doctor blade method, a calender roll method, and a rolling method, to produce a green sheet.

As the conductor paste for the wiring conductor layer 4, molybdenum or tungsten is used as a main metal component based on a solid component other than the organic component, and AlN and Y are contained with respect to 100 parts by weight of the metal component. A ceramic component containing at least one compound of the rare earth elements and at least one compound of the alkaline earth elements is added at a ratio of 5 to 15 parts by weight. At this time, the content of the sintering aid component with respect to AlN is 3% of the content of the sintering aid component with respect to AlN in the AlN molded body.
Mix up to 6 times.

The rare earth element compound and the alkaline earth element compound containing Y used in the above may be oxides or carbonates, nitrates and acetates capable of forming oxides by firing.

Then, the conductor paste is applied on the AlN green sheet in a pattern by screen printing. When the wiring conductor layer 4 is formed, a green sheet is punched by a die press, or a gap for the wiring conductor layer having a predetermined shape is formed by laser processing, and then the conductor paste is filled in the gap with a printing method or a dispenser. Fill with. At this time, the thickness of the wiring conductor layer can be freely changed by changing the thickness of the green sheet forming the void. That is, it can be dealt with by arbitrarily changing the shape and thickness of the wiring conductor layer in consideration of the current value allowed by the wiring and the heat generation amount of the electronic component.

When the via-hole conductor 3 is formed, a via hole having a diameter of 50 μm to 250 μm is formed on the green sheet by a microdrill, a laser, or the like, and the via paste is filled in the via hole. Thereafter, the green sheets on which the conductive paste is applied by printing are aligned and pressure-bonded by lamination, and the laminated body is placed in a non-oxidizing atmosphere such as a hydrogen-nitrogen mixed atmosphere at 1600 to 1400.
By baking at a temperature of 800 ° C., the insulating substrate 1 and the wiring conductor layer 4, the general conductor layer 2, and the via-hole conductor 3 can be formed by simultaneous baking.

[0036]

EXAMPLE For sintering at high temperature, 100 parts by weight of AlN were mixed at a ratio of 8.0 parts by weight of erbium oxide, and an acrylic resin was added and mixed as a binder, and the mixture was molded by a doctor blade method. An AlN green sheet was produced.

For low-temperature sintering, 1.0 parts by weight of strontium oxide and 1.0 part by weight of aluminum oxide were added to the above composition.
After adding 0 parts by weight, an AlN green sheet was prepared by the doctor blade method in the same manner as described above.

Next, tungsten (W) or molybdenum (Mo), AlN, and various sintering aid components were mixed with the green sheet for high-temperature sintering so that the composition shown in Table 1 was obtained. A cellulosic resin was added as a binder to the powder, and a phthalic acid-based organic solvent was mixed and dispersed to prepare a conductor paste for a high-temperature fired substrate.

In the same manner as above, a low-temperature fired substrate was mixed so as to have the composition shown in Table 2, and a binder and an organic solvent were added to prepare a low-temperature fired substrate conductor paste.

Next, a predetermined portion of the green sheet having a thickness of 30 to 300 μm was punched out by a die to a width of 5 mm and a length of 30 m.
After the formation of the voids of m, the green sheets were laminated and pressed on one side only. Then, the above-mentioned conductor paste is filled with 1
Filled by 65 mesh screen printing. Then N
_In an atmosphere of ₂ and H ₂ , firing was performed at the firing temperature shown in Table 1 for a high-temperature fired substrate and Table 2 for a low-temperature fired substrate to produce an AlN substrate having a wiring conductor layer having the thickness shown in the table.

It should be noted that AlN produced by high-temperature firing was used.
The thermal conductivity of the porous sintered body was 170 W / m · K, and the thermal conductivity of the AlN sintered body produced by low-temperature firing was 120 W / m · K.
m · K.

With respect to the AlN-based wiring board thus obtained, the surface warpage of the wiring conductor layer was measured by a shape measuring machine using a laser. Further, X-ray transmission analysis and cutting of the substrate, and SEM analysis of the wiring conductor layer were performed to confirm the sintering state of the wiring conductor layer, the presence or absence of cracks, and the presence or absence of peeling at the porcelain interface. Further, the electric resistance of the wiring conductor layer was measured by a four-terminal method.

[0043]

[Table 1]

[0044]

[Table 2]

According to the results of Tables 1 and 2, Sample No. 10
When the content of the ceramic component including AlN in the wiring conductor layer is less than 5 parts by weight, the warpage of the substrate increases. When the amount was more than 15 parts by weight as in 14, the electric resistance was increased. In addition, the sample No. 1, 7,
When the amount of the sintering aid component is less than three times the amount of the auxiliary component in the AlN sintered body as in 17, 23, 29, 35, and 41, the sintering around the wiring conductor layer and the wiring conductor layer is suppressed. Poor sintering of the body resulted in an increase in the electrical resistance of the wiring conductor layer and cracking and peeling of the wiring conductor layer. In addition, the sample No. 6,
When the amount of the sintering aid component is more than 6 times the amount of the auxiliaries component in the AlN sintered body as in 16, 22, 28, 34, 40, and 46, the warpage of the substrate is large, and electronic components and the like are generated. Had an effect on the implementation of

On the other hand, all of the samples of the present invention show good sinterability, have a small surface warpage of the wiring conductor layer, a small electric resistance, and are free from peeling and cracks on the insulating substrate. It could be prevented from occurring.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an example of an AlN-based wiring board of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating board 2 General conductor layer 3 Via hole conductor 4 Wiring conductor layer

Claims (4)

[Claims] 1. An insulating substrate of an AlN sintered body containing a main component composed of AlN and a sintering aid component, and a wiring conductor layer having a thickness of 30 μm or more on the surface or inside of the insulating substrate. A wiring substrate, wherein the wiring conductor layer is formed of a metal component mainly composed of at least one of molybdenum and tungsten, and 5 to 15 parts by weight based on 100 parts by weight of the metal component.
Parts by weight of a ceramic component, wherein the ceramic component includes AlN and a sintering aid component, and the content of the sintering aid component with respect to AlN in the wiring conductor layer is an AlN sintered body. A wiring substrate, wherein the content of the sintering aid component is 3 to 6 times the content of AlN. 2. The sintering aid component in the AlN sintered body includes at least one of Y-containing rare earth elements and / or
2. The wiring board according to claim 1, wherein at least one of the alkaline earth elements is contained in a ratio of 2 to 20 parts by weight per 100 parts by weight of AlN in terms of oxide. 3. A sintering aid component in a wiring conductor layer, wherein at least one of Y-containing rare earth elements and / or at least one of alkaline earth elements are converted to oxides in total per 100 parts by weight of AlN. The wiring board according to claim 1, wherein the wiring board is contained in an amount of 10 to 70 parts by weight. 4. A wiring conductor layer containing the same element as a rare earth element and / or an alkaline earth element contained as a sintering aid component in the AlN sintered body. Item 3. The wiring board according to Item 3.