JPH05136572A - Manufacture of multilayered ceramic board - Google Patents

Abstract

PURPOSE:To obtain a multilayered board which shrinks only in a thicknesswise direction but not in a planar direction at burning by a method wherein a green sheet formed of inorganic composition is laminated on a green sheet laminate which includes organic binder and plasticizer. CONSTITUTION:A green sheet is formed of glass-ceramic for low temperature sintering, which contains, at least, organic binder and plasticizer. An electrode pattern of conductor paste composition is formed on the green sheet. Another green sheet 3 where an electrode has been formed is laminated on the above green sheet. A green sheet 4 formed of inorganic composition which is not sintered at the sintering temperature of the glass-ceramic is formed on one surface or both surfaces of a green sheet laminated board 1 formed of the glass-ceramic so as to sandwich it between them and sintered. Thereafter, the non-sintered inorganic composition layer 4 is impregnated and filled with resin, and an outermost wiring layer 5 is formed. By this setup, a multilayered ceramic board which is restrained from shrinking in a planar direction and excellent in mechanical strength can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic multilayer wiring board for mounting semiconductor LSIs, chip parts, etc., and interconnecting them, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the development of a low temperature sintered glass / ceramic multilayer substrate, usable conductor materials include gold, silver,
Copper, palladium or mixtures thereof have come into use. These metals have lower conductor resistance than conventionally used tungsten, molybdenum, etc., and the equipment that can be used is safe and can be manufactured at low cost.

On the other hand, of these metals, the precious metal gold,
Since silver and palladium are expensive and have large price fluctuations, it is desired to use Cu electrode materials that are inexpensive and have little price fluctuations.

Here, an example of a typical manufacturing method of these low temperature sintered multilayer substrates will be described. There are roughly three types of low-temperature sintering multilayer substrates.

First, silver is used for the inner layer electrodes of the multilayer substrate, a desired number of green sheets of low temperature sintered substrates are stacked and fired in air, and then silver and palladium paste is printed and fired on the uppermost layer. Is obtained. This uses silver with low impedance inside and silver / palladium having solder heat resistance as the uppermost layer.

The second method is to use silver for the internal electrodes as in the former case and copper for the uppermost layer. By using copper for the uppermost layer wiring, the impedance and solder wetting are lower than those of the former silver and palladium. It is effective in terms of. However, since the copper used for the uppermost layer has a low eutectic temperature with silver, a low temperature fired copper paste of about 600 ° C. must be used. As a result, there are many problems in terms of adhesive strength and solder wetting.

Finally, as a third method, there is a method of using copper electrodes for the inner layer and the uppermost layer. Although it is the best in terms of conductor resistance, solder wettability, and cost, it must be fired in a neutral atmosphere such as nitrogen, and its manufacture is difficult. Generally, in order to use a copper electrode, a wiring pattern is formed by screen-printing a Cu paste on a substrate, and after drying, at a temperature below the melting point of Cu (about 850 to 950 ° C.) and Cu
Is fired in a nitrogen atmosphere whose oxygen partial pressure is controlled so that the organic components in the conductor paste are sufficiently burned without being oxidized. In the case of multiple layers, the insulating layer is obtained by printing and firing under the same conditions.

However, it is difficult to control the atmosphere in the firing step under an appropriate oxygen partial pressure, and in the case of forming multiple layers, it is necessary to repeat firing each time after printing each paste, resulting in a long lead time. There are issues such as increased costs for equipment.

Japanese Patent Application No. 59-147833 has already disclosed a method of preparing a ceramic multilayer substrate by using a cupric oxide paste in three steps of a binder removal step, a reduction step and a firing step. .. It uses cupric oxide as a starting material for a conductor to form a multilayer body, and in the binder removal step, heat treatment is performed in a sufficient oxygen atmosphere for carbon and at a temperature sufficient to thermally decompose the organic binder inside. Next, the reduction step of reducing cupric oxide to copper and the firing step of sintering the substrate are established. As a result, the control of the atmosphere during firing becomes easy and a dense sintered body can be obtained.

[0010]

However, the ceramic multi-layer substrate has the following problems. That is, when the ceramic multilayer substrate is fired, shrinkage occurs due to sintering. The shrinkage due to the sintering varies depending on the substrate material used, the green sheet composition, the powder lot, and the like. This has caused some problems in the fabrication of multilayer substrates.

First, in the production of a multilayer ceramic substrate, the inner layer wiring is fired as described above before the uppermost layer wiring is formed. Therefore, if the shrinkage error of the substrate material is large, the uppermost layer wiring pattern and the dimensional error will occur. Therefore, the connection with the inner layer electrode cannot be performed. As a result, a land having an unnecessarily large area has to be formed in the uppermost electrode portion so as to allow a shrinkage error in advance, and it cannot be used in a circuit that requires high-density wiring. In addition, a method has been adopted in which some screen plates for the uppermost wiring are prepared according to the shrinkage error and used according to the shrinkage rate of the substrate. This method is uneconomical because many screen versions must be prepared.

On the other hand, if the uppermost layer wiring is carried out at the same time as the inner layer firing, a large land is not required, but since the shrinkage error of the substrate itself still exists even by this simultaneous firing method, in the cream solder printing at the time of the last component mounting. However, due to the error, there may be a case where it is not possible to print on the necessary part.
Also, when mounting components, a predetermined component position and displacement occur.

Secondly, the shrinkage rate of the multi-layer substrate formed by the green sheet laminating method is different depending on the film-forming direction of the green sheet depending on the width direction and the longitudinal direction. This is also an obstacle to the production of the ceramic multilayer substrate.

In order to reduce these shrinkage errors as much as possible, it is necessary to control not only the substrate material and the green sheet composition but also the difference in powder lot and the laminating conditions (press pressure, temperature) in the manufacturing process. There is.
However, it is generally said that the error of the shrinkage ratio is about ± 0.5%.

This is a problem common to ceramics and glass-ceramics regardless of the multilayer substrate, and the sintering of the substrate material occurs only in the thickness direction.
If a substrate with zero shrinkage in the plane direction can be produced, the above problems can be solved and it is extremely effective in industry.

Further, although the ceramic substrate is a multi-layer substrate suitable for high-density mounting, it has an unavoidable problem in view of machinability and mechanical strength in addition to lack of dimensional stability as described above.

[0017]

In order to solve the above problems, a green sheet containing at least an organic binder and a plasticizer in a glass / ceramic low temperature sintered substrate material is prepared,
An electrode pattern is formed from the conductor paste composition, and a desired number of the green sheet and another green sheet on which an electrode pattern has been formed are laminated. Then, on both sides or one side of the green sheet laminated body made of the low temperature sintered glass / ceramic, sandwiched by green sheets made of an inorganic composition that does not sinter at the firing temperature of the glass / ceramic low temperature sintered substrate material. Laminate and fire the laminate. After that, the inorganic composition layer that does not sinter is impregnated and filled with resin, and further the uppermost wiring is formed, so that shrinkage during firing does not occur in the planar direction, and a multilayer ceramic substrate with good mechanical strength is produced. It is a thing.

[0018]

According to the present invention, the glass / ceramic substrate shrinks only in the thickness direction during firing and does not shrink in the planar direction by performing the above-mentioned steps, and it has good mechanical strength. is there. The operation of the present invention will be described below.

First, according to the manufacturing method of the present invention, a green sheet containing at least an organic binder and a plasticizer is prepared on a glass / ceramic low temperature sintered substrate material, an electrode pattern is formed by a conductor paste composition, and the green sheet is separated from the green sheet. The desired number of green sheets with the electrode pattern formed thereon are laminated to form a multilayer, and the green sheet laminate made of the low temperature sintered glass / ceramic is laminated on both sides or one side at the firing temperature of the glass / ceramic low temperature sintered substrate material. A green sheet having a via hole formed of an inorganic composition which is not sintered is laminated. Thereby, even if the laminate is fired
No shrinkage occurs except in the thickness direction. It is considered that this is because the material is sandwiched between the non-sintering materials laminated on both sides or one side, and thus the contraction in the plane direction is prevented. After that, a resin is impregnated and filled in the inorganic layer that is not sintered. Further, the uppermost layer wiring is formed to obtain a desired substrate.

Firing of the glass-ceramic laminate is usually performed in the range of 800 ° C to 1000 ° C. Copper electrode,
If a silver electrode is used, it is performed at 900 ° C. In addition, the inorganic component of the inorganic composition green sheet that does not sinter at the firing temperature of the glass / ceramic low temperature sintering substrate material is Al
_The green sheet includes at least one of ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , BeO, and BN. 9
The low temperature sintering substrate material to be performed at a firing temperature of 00 ° C. is Al
₂ O ₃ is the most effective.

It is also effective to add a small amount of a sintering aid to Al ₂ O ₃ to form a porous sintered body after sintering and impregnate with a resin.

When the glass / ceramic laminate is pressed and fired at the time of firing the glass / ceramic laminate, sinterability in the thickness direction is further promoted and a dense sintered body is obtained.

The inorganic layer which is not sintered is a porous layer, and as a method of filling the resin in the opening, a method of heating and melting and impregnating the resin, and a method of melting and impregnating the resin in a solvent , A method of impregnating in a monomer state to make a resin.

[0024]

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a cross section of a green sheet laminate according to an embodiment of the present invention.

First, a method for producing a multilayer ceramic substrate will be described. The manufacturing process of the present invention was performed by the method shown in FIG.

As the glass ceramic of the substrate material, a composition (MLS-19 manufactured by Nippon Electric Glass Co., Ltd.) was used in which lead borosilicate glass powder and alumina powder as a ceramic material were mixed in a weight ratio of 50:50. This glass / ceramic powder is used as an inorganic component, polyvinyl butyral as an organic binder, di-n-butyl phthalate as a plasticizer, and a mixed liquid of toluene and isopropyl alcohol as a solvent (30
(70 weight ratio) was mixed to form a slurry.

This slurry was formed into a sheet on an organic film by the doctor blade method. At this time, drying from film formation,
A system was used in which each step of punching and, if necessary, via hole processing was continuously performed. A conductive pattern was formed on the green sheet using silver paste and via hole filling printing was performed by a screen printing method. As the conductor paste, a glass frit (GA-9 glass powder manufactured by Nippon Electric Glass Co., average particle size 2.5 μm) for obtaining adhesive strength to Ag powder (average particle size 1 μm) was used in an amount of 5 w.
What added t% was made into the inorganic component, and ethyl cellulose which is an organic binder was added together with the vehicle which melt | dissolved in terpineol, and it mixed so that it might become suitable viscosity with the 3-step roll. The via-filling Ag paste was prepared by further adding 15% by weight of the glass-ceramic powder as an inorganic component.

Next, a green sheet that does not sinter is produced by using alumina (AL- manufactured by Sumitomo Aluminum Co., Ltd.) as an inorganic component.
41 A green sheet was prepared by using the same method as the green sheet for a glass / ceramic substrate with the same method, using only powder having an average particle size of 1.9 μm.
The substrate green sheet has a thickness of about 200 μm, and the alumina green sheet has a thickness of about 300 μm.

Via holes are formed in this alumina green sheet as described above. Further, a predetermined number of printed green sheets for the substrate are stacked, and further the alumina green sheets are stacked on both sides thereof. In this state, thermocompression bonding was performed to form a laminate. The thermocompression bonding conditions were a temperature of 80 ° C. and a pressure of 200 Kg / cm ² . The structure is shown in FIG. Reference numeral 1 is a green sheet layer made of the substrate material, 2 is a green sheet layer made of alumina, and 3 is an inner electrode layer.

Next, the laminate is placed on a 96% alumina substrate and baked. The condition is 900 in air by a belt furnace.
The firing was performed at 1 ° C. for 1 hour. (The holding time at 900 ° C. is about 12 minutes.) At this time, in order to assist the warp of the substrate and the sintering shrinkage in the thickness direction, an alumina sintered substrate was placed and pressed to perform firing.

The fired laminate was heated in a vacuum, and epoxy resin was dropped on the surface of the laminate. As a result, the unsintered alumina layer on the surface of the laminate was filled with the epoxy resin.

The shrinkage of the substrate after firing was less than 0.05%. The surface of the substrate after resin filling was slightly polished so that the via wiring was exposed on the surface, and further Cu plating with a thickness of about 35 μm was performed on the entire surface by electroless plating. After that, a desired wiring pattern was formed by an etching method.

As a result, a multilayer substrate having good mechanical strength without shrinkage in the plane direction could be produced. Since the shrinkage of the wiring in the ceramic part was extremely small, there was no deviation in the formation of the uppermost wiring pattern.

FIG. 3 is a sectional view of the multi-layer substrate manufactured in this way. (Embodiment 2) Hereinafter, a second embodiment of the present invention will be described.

The glass / ceramic green sheet as the substrate material had the same composition as in (Example 1). A conductor pattern was formed on the green sheet by using CuO paste and via hole filling printing was performed by a screen printing method. The conductor paste is CuO powder (average particle size 3μ
m) glass frit for obtaining adhesive strength (LS-0803 glass powder manufactured by Nippon Electric Glass Co., Ltd., average particle size 2.5)
was added as an inorganic component together with a vehicle in which terpineol was dissolved as an organic binder, and the mixture was mixed by a three-stage roll so as to have an appropriate viscosity. The CuO paste for filling vias was prepared by further adding 15% by weight of the above glass-ceramic powder as an inorganic component.

Next, a green sheet which does not sinter is produced by using only beryllium oxide (an average particle diameter of 1 μm, manufactured by Kanto Chemical Co., Inc.) powder as an inorganic component, with the same green sheet composition as the green sheet for glass / ceramic substrates.
A green sheet was prepared by the same method and a via hole was formed.

The thickness of the green sheet for the substrate is about 20.
0 μm, alumina green sheet is about 300 μm.

A predetermined number of the printed green sheets for the substrate are stacked, and the alumina green sheets are stacked on both sides of the stacked green sheets. In this state, thermocompression bonding was performed to form a laminate. The temperature for thermocompression bonding is 80
The temperature was 200 ° C. and the pressure was 200 kg / cm ² .

Next, the firing process will be described. The first is a binder removal step. The organic binders of the green sheet and CuO paste used in the invention are PVB and ethyl cellulose. Therefore, the decomposition temperature in air should be 500 ° C. or higher, so 600 ° C. was used. Then, the laminated body was reduced in an atmosphere of 100% hydrogen gas at 200 ° C. for 5 hours. When the Cu layer at this time was analyzed by X-ray diffraction, it was confirmed to be 100% Cu. Next, in the firing step, firing was performed in pure nitrogen in a mesh belt furnace at 900 ° C.

The beryllium oxide unsintered layer on the surface of the laminated body produced as described above is filled with resin in the same manner as in (Example 1). In the method, a polyimide monomer state melted with a chloroform solvent was dropped. Thereafter, the surface of this laminate is polished, copper foil having a thickness of 35 μm is laminated, and a polyimide layer is formed by heat treatment at 300 ° C. This strengthened the bond between the copper foil and the polyimide layer. Further, a wiring pattern was formed on this surface layer by etching. When the shrinkage rate of the substrate thus produced was evaluated, it was found to be 0.05% or less.

In this embodiment, Al ₂ O ₃ and BeO were used as the unsintered materials, but other materials such as MgO and Zr were used.
The same effect was obtained by using O ₂ , TiO ₂ , and BN.
Although the green sheet layers were formed on both sides, the same effect could be obtained even if only one side was laminated by applying a heavy load. However, when pressure is not applied, the substrate warps because it works so as to sinter only the non-laminated surface.

As described above, in this embodiment, when a green sheet layer made of an inorganic component that does not sinter is provided in the process for producing a multilayer ceramic substrate and the substrate is fired, shrinkage due to sintering does not occur in the plane direction at all. A multi-layered substrate can be obtained and has good dimensional stability, and it is possible to directly mount a semiconductor or the like.

[0043]

According to the present invention, by carrying out the steps as described above, it is possible to obtain a multilayer substrate in which the glass-ceramic substrate shrinks only in the thickness direction during firing and does not shrink in the planar direction, and the mechanical strength is good. The thermal expansion coefficient is close to that of semiconductors. This makes it possible to always obtain a substrate having the same size regardless of the substrate material used for the multilayer substrate, the green sheet composition, the powder lot, and the like. Similarly, in the production of the multilayer ceramic substrate, even if the innermost layer wiring is fired and then the uppermost layer wiring is formed as described above, the uppermost layer wiring pattern and the inner layer can be completely connected. As a result, the land area for connection can be reduced, and a high-density multilayer wiring board can be obtained. Furthermore, the number of screen plates is small, and it is economical because there is no need to back-calculate the shrinkage factor and expand the inner layer pattern in the board design.

As described above, this is an extremely effective invention in that it solves the problem of shrinkage error, which is the biggest drawback of the green sheet laminating method, and that it has good mechanical strength.

[Brief description of drawings]

FIG. 1 is a sectional view of a green sheet laminate according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a manufacturing method of the present invention.

FIG. 3 is a sectional view of a completed substrate according to an embodiment of the present invention.

[Explanation of symbols]

 1 Glass / Ceramic Green Sheet Layer 2 Alumina Green Sheet Layer 3 Internal Electrode Layer 4 Resin Filling Layer 5 Top Wiring Layer

Front page continued (72) Inventor Yoshifumi Nakamura 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor, Kazuhiro Miura 1006 Kadoma, Kadoma City Osaka Prefecture (72) Invention Person Nishinobu Hidenobu 1006, Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (15)

[Claims] 1. A glass containing at least an organic binder having an electrode pattern formed of a conductor paste composition and a plasticizer.
Stack the desired number of ceramic green sheets,
A green sheet made of an inorganic composition that does not sinter at the firing temperature and is filled with via holes with the electrode material is laminated on both sides or one side of the green sheet laminate, and then the firing treatment is performed, and then the non-sintering inorganic A method for producing a multilayer ceramic substrate, characterized in that the composition layer is filled with a resin, and conductor wiring is formed on both sides or one side. 2. The method for producing a multilayer ceramic substrate according to claim 1, wherein the firing temperature is 800 ° C. to 1000 ° C. 3. A green sheet made of an inorganic composition that does not sinter in the firing treatment is Al ₂ O ₃ , MgO, ZrO ₂ , T.
_{2. The} method for producing a multilayer ceramic substrate according to claim 1, comprising a green sheet containing at least one of iO ₂ , BeO and BN. 4. A resin selected from an epoxy resin, a polyimide resin, a silicon resin, an acrylic resin, a phenol resin, and a urethane resin is used as a resin to be filled in the inorganic composition layer that is not sintered by the firing treatment. Claim 1
A method for manufacturing the multilayer ceramic substrate described. 5. The conductive paste is Ag, Ag / Pd, Ag
2. The method for producing a multilayer ceramic substrate according to claim 1, wherein any one of / Pt and Cu is contained as a main component. 6. The method for manufacturing a multilayer ceramic substrate according to claim 1, wherein the green sheet laminate is pressed during the baking process to be baked. 7. The wiring is formed by laminating and etching copper foil after resin impregnation.
A method for manufacturing the multilayer ceramic substrate described. 8. The method for producing a multilayer ceramic substrate according to claim 1, wherein after impregnating the resin, the entire surface layer is plated with copper and wiring is formed by an etching method. 9. A desired number of green sheets made of glass / ceramic containing at least an organic binder and a plasticizer, in which an electrode pattern is formed of a conductor paste composition containing cupric oxide as a main component, are laminated in a desired number, and the green sheet laminate is formed. After laminating a green sheet made of an inorganic composition which is filled with a via hole with the electrode material and does not sinter at the firing temperature, the organic binder inside the multilayer body decomposes and scatters in the air. An inorganic composition which is heat-treated at a temperature and then subjected to a reduction heat treatment in an atmosphere of hydrogen or a mixed gas of hydrogen and nitrogen, and further, the reduction heat-treated multilayer body is sintered in a nitrogen atmosphere, and then not sintered. A method for manufacturing a multilayer ceramic substrate, characterized in that a layer is filled with a resin, and conductor wiring is formed on both sides or one side. 10. The method for producing a multilayer ceramic substrate according to claim 9, wherein the firing treatment is performed in the range of 800 ° C. to 1000 ° C. 11. An inorganic composition group that does not sinter in a firing process.
The lean sheet is made of Al ₂O₃, MgO, ZrO₂, Ti
O₂, BeO, BN, containing at least one or more of
The lean sheet as claimed in claim 9.
Manufacturing method of multilayer ceramic substrate. 12. A resin selected from an epoxy resin, a polyimide resin, a silicon resin, an acrylic resin, a phenol resin, and a urethane resin is used as a resin to be filled in the inorganic composition layer that is not sintered in the firing treatment. The method for manufacturing a multilayer ceramic substrate according to claim 9. 13. The method for producing a multilayer ceramic substrate according to claim 9, wherein the green sheet laminate is pressed during the firing process to perform firing. 14. The method for manufacturing a multilayer ceramic substrate according to claim 9, wherein the wiring is formed by laminating and etching copper foil after impregnating the resin. 15. The method for producing a multilayer ceramic substrate according to claim 9, wherein after impregnating with the resin, the entire surface layer is plated with copper and wiring is formed by an etching method.