JPH05327218A - Manufacture of multilayer ceramic base - Google Patents

Abstract

PURPOSE:To obtain a multilayer base of which a glass-ceramic base shrinks only in the direction of thickness and not in the direction of plane at the time of baking. CONSTITUTION:A green sheet 1 is made of a glass-ceramic low-temperature sintered base material made to contain an organic binder and a plasticizer, electrode patterns 3 are formed of a conductor paste composition and a plurality of the sheets are laminated. Thereafter, lamination is made so that the green sheet laminate is held on the opposite sides by green sheets 2 of glass which are not crystallized at the baking temperature of a glass-ceramic base, but start to be crystallized at the crystallization completion temperature of glass- ceramic or above and are sintered. As for a baking process, binder removal for removing an organic substance is executed, then a temperature is raised to and kept at the temperature of crystallization of a glass-ceramic composition of an inner layer, and after the crystallization of this glass-ceramic composition of the inner layer is completed, the temperature is further raised to and kept at the temperature of the crystallization of the glass laminated on the opposite sides. After the crystallization is completed, crystallized substances on the opposite sides are removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multi-layer ceramic substrate for mounting semiconductor LSIs, chip parts, etc. and interconnecting them.

[0002]

2. Description of the Related Art In recent years, semiconductor LSIs, chip parts and the like have been made smaller and lighter, and wiring boards for mounting them have also been desired to be smaller and lighter. In order to meet such demands, the ceramic multilayer substrate has obtained the required high-density wiring, and since it can be thinned, it is regarded as important in today's electronics industry.

The conductor composition as an electrode material used in this ceramic multilayer substrate is generally a paste composition in which a conductive metal, an inorganic oxide and glass powder are dispersed in an organic medium. In recent years, with the development of low-temperature sintered glass / ceramic multilayer substrates, usable conductor materials are 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, base metals based on cheap prices and low price fluctuations have been used. Among them, since copper has a low specific resistance and an excellent solder wettability, use of a copper electrode material is desired.

Here, an example of a typical manufacturing method using copper for these low temperature sintered multilayer substrates will be described. One is obtained by using silver for the inner layer electrodes of a multilayer substrate, stacking a desired number of green sheets of low-temperature sintered substrates, firing in air, and then printing and firing silver and copper on the top layer. (See, for example, Japanese Patent Laid-Open No. 3-78798). This uses silver and copper, which have low impedance. 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. The second method is to use copper electrodes for the inner layer and the uppermost layer. Best in terms of conductor resistance, solder wettability, and cost,
All of them have to be fired in a neutral atmosphere such as nitrogen and are difficult to manufacture. Generally, to use a copper electrode, a wiring pattern is formed by screen-printing a Cu paste on a substrate, and after drying, a temperature (850 to 9) below the melting point of Cu is used.
Firing is performed at about 50 ° C.) in a nitrogen atmosphere in which the oxygen partial pressure is controlled so that Cu is not oxidized and the organic components in the conductor paste are sufficiently burned. 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, which leads to a long lead time and an increase in equipment costs (Japanese Patent Application No. 55-12889).
9). Therefore, in Japanese Unexamined Patent Publication (Kokai) No. 3-20914, cupric oxide paste is used in manufacturing a ceramic multilayer substrate,
A method having three steps of a binder removal step, a reduction step, and a firing step has already been disclosed. It uses cupric oxide as a starting material of 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.

On the other hand, the ceramic multi-layer substrate shrinks due to sintering during firing. 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 manufacturing a multilayer ceramic substrate, the inner layer wiring is fired as described above and then the uppermost layer wiring is formed. Therefore, when the shrinkage error of the substrate material is large, the inner layer wiring pattern and the dimensional error cause the inner layer wiring to have a large dimensional error. Cannot connect to the electrode. 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. Therefore, some screen plates may be prepared for the uppermost layer wiring 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.

Also, 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, There may be a case where the necessary portion cannot be printed due to the error.
Also, when mounting components, a predetermined component position and displacement occur.

Secondly, the shrinkage rate of the multi-layered substrate formed by the green sheet laminating method varies 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 lamination conditions (pressing pressure, temperature) in the manufacturing process. is there. However, it is generally said that the error of the shrinkage ratio is about ± 0.5%.

This is a common problem with ceramics and glass-ceramics sintering, regardless of the multilayer substrate. Therefore, in Japanese Patent Application No. 3-257553, a desired number of green sheets made of low temperature sintered glass / ceramic with electrode patterns are laminated, and the glass / ceramic low temperature sintered substrate material is laminated on both sides or one side of the laminated body. The invention has been made in which green sheets made of an inorganic composition that does not sinter at the firing temperature are laminated so as to be sandwiched, the laminate is fired, and then the inorganic composition that does not sinter is removed. As a result, the substrate material is sintered only in the thickness direction, and a substrate having no shrinkage in the plane direction can be manufactured, and the above problems can be solved.

[0011]

However, although a substrate which does not shrink in the planar direction has been produced from the above, there are some problems. The point is to remove the inorganic composition that does not sinter at the firing temperature of the glass-ceramic low-temperature sintered substrate material laminated on both sides or one side of the low-temperature sintered glass-ceramic laminate to obtain an unshrinkable substrate. This unsintered inorganic composition is removed by ultrasonic cleaning, but this is because the multi-layered substrate is passed through a wet process, and the effects such as swelling of the multi-layered substrate are also considered. It will be one step more than the process of. Also,
In the part of the via where the conductor appears on the ceramic substrate surface, the conductor in the via reacts with the inorganic composition on the surface during firing, and the unsintered inorganic composition on the via part is removed by ultrasonic cleaning. Even if a method such as polishing or polishing is performed, it cannot be removed sufficiently and it takes a long time. Therefore, a method that can be removed in a shorter time is required.

In consideration of the above problems of the conventional manufacturing method, the present invention provides a multilayer ceramic substrate in which the multilayer substrate does not swell, the number of steps is small, and the unsintered inorganic composition can be removed in a short time. It is intended to provide a manufacturing method.

[0013]

According to 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 with a conductor paste composition, and the green sheet is prepared. And a plurality of different electrode pattern formed green sheets are laminated.
After that, crystallization does not occur on both surfaces of the green sheet laminated body composed of the low-temperature sintered glass / ceramic at the glass / ceramic substrate firing temperature, and crystallization begins and sinters at the glass / ceramic crystallization end temperature or higher. It is laminated so as to be sandwiched between glass or a green sheet made of glass and ceramic. Then, as a firing treatment of the laminate, after removing the binder to remove organic matter,
After the crystallization temperature of the glass-ceramic composition of the inner layer is raised and maintained, and after the crystallization of the glass-ceramic composition of the inner layer is completed, the crystallization temperature of the glass or the glass and ceramic mixture further laminated on both surfaces. The temperature is raised to and maintained. After the crystallization is completed, the crystallized substances on both sides are removed.

[0014]

[Function] 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 a green sheet on which an electrode pattern has been formed is formed separately from the green sheet. A plurality of sheets are laminated to form a multilayer, and the green sheet laminated body made of the low temperature sintered glass / ceramic does not cause crystallization behavior at the crystallization temperature of the glass / ceramic low temperature sintered substrate material, A green sheet made of glass or a mixture of glass and ceramic is laminated, which starts crystallization after the completion of the ceramic crystallization temperature and causes sintering. As a result, even if the laminate is fired, no shrinkage occurs except in the thickness direction. This is because the glass-ceramic laminate is sandwiched between the softening point of the glass, which causes shrinkage, and the sintering, and is sandwiched by materials that do not cause the sintering behavior on both sides. It is thought to be done. Then, after the glass / ceramic laminate is completely sintered, the materials laminated on both sides are sintered and contract in the plane direction. Because of this, the required removal from the glass-ceramic laminate is easy. Thus, a glass-ceramic substrate that does not shrink in the planar direction is finally obtained.

The firing of the glass-ceramic laminate is 8
It is carried out in the range of 00 ° C to 1100 ° C. When a copper electrode or a silver electrode is used, it is performed at 950 ° C.

The inorganic components of the green sheet of the glass / inorganic composition mixture which does not sinter at the firing temperature of the glass / ceramic low temperature sintering substrate material include Al ₂ O ₃ , MgO, Z.
The green sheet contains at least one of rO ₂ , TiO ₂ , BeO, and BN.

When the glass-ceramic laminate is pressed and fired when firing the glass-ceramic laminate, sinterability in the thickness direction is further promoted and a dense sintered body is obtained.

Glass laminated on both sides, or glass
Since the ceramic mixture has been crystallized, it can be easily removed and the working time can be shortened.

By the above method, it is possible to manufacture a glass-ceramic substrate in which shrinkage during firing does not occur in the plane direction, and the work of removing the laminated body on both sides becomes easy.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a cross section of a multilayer ceramic substrate according to an embodiment of the present invention.

(Example 1) First, a method for producing a multilayer ceramic substrate will be described.

For the glass / ceramic of the substrate material, a composition (MLS-27 softening point 870 ° C. by Nippon Electric Glass Co., Ltd.) in which the weight ratio of lead borosilicate glass powder to alumina powder as the ceramic material is 50:50 is used. I was there. This glass / ceramic powder was used as an inorganic component, polyvinyl butyral as an organic binder, di-n-butyl phthalate as a plasticizer, and a mixed solution of toluene and isopropyl alcohol (30:70 weight ratio) as a solvent 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-8 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 4 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, crystallization does not occur at the glass / ceramic substrate firing temperature, but crystallization begins after the glass / ceramic crystallization temperature starts and sinters. A green sheet made of a mixture of glass and an inorganic composition is prepared using an inorganic component. As alumina (AL-41 made by Sumitomo Chemical Co., Ltd. average particle size 1.9
Glass frit (aluminum borosilicate glass manufactured by Nippon Electric Glass Co., Ltd., softening point: 930 ° C. GA-33 glass powder, average particle size: 2.5 μm) added to powder in an amount of 5 wt% is used. A green sheet was prepared by the same method with the same green sheet composition as the green sheet for use. The thickness of the substrate green sheet is about 200 μm, and the thickness of the alumina green sheet is about 250 μm.
Is.

A predetermined number of printed green sheets for the substrate are stacked, and crystallization does not occur on both surfaces of the glass / ceramic substrate at the firing temperature.
A green sheet made of a mixture of glass and an inorganic composition, which begins to crystallize after the glass / ceramic crystallization temperature is completed and is sintered, is superposed. In this state, thermocompression bonding was performed to form a laminate. The thermocompression bonding conditions are a temperature of 80 ° C. and a pressure of 200.
It was Kg / cm ² . The structure is shown in FIG. A plurality of green sheet layers 1 made of the substrate material are provided, and on both surfaces thereof, crystallization does not occur at the glass / ceramic substrate calcination temperature, and crystallization starts after the glass / ceramic crystallization temperature ends and the inorganic composition A green sheet layer 2 made of a mixture of substances is formed, and an inner electrode layer 3 is provided inside.

Next, the laminate is placed on a 96% alumina substrate and baked. The conditions are 500 in air by a belt furnace.
After the binder removal was completed at ℃, baking was performed at 950 ° C for 1 hour (at this time, baking was performed at 880 ° C for about 10 minutes.
C. is held for about 12 minutes to perform two-stage sintering).
At this time, in order to assist the warp of the substrate and the sintering shrinkage in the thickness direction, the alumina sintered substrate was placed and pressed so as to be fired.

There was a sintered body after suppressing the shrinkage of the ceramic substrate on both sides of the fired ceramic laminate, which could be easily removed.

When the shrinkage ratio of the substrate after firing is measured,
The shrinkage ratio was 0.1% or less. As a result, it was possible to manufacture a multi-layer substrate that does not shrink in the planar direction. Further, the uppermost layer pattern was screen-printed on this multilayer substrate with a silver / palladium paste, and drying and baking were performed in the same manner as described above. Since the shrinkage of the inner layer substrate was extremely small, there was no print displacement of the uppermost layer pattern.

(Example 2) As the glass / ceramic green sheet of the substrate material, the same composition as in Example 1 was used. 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 was an inorganic component obtained by adding 3 wt% of glass frit (LS-0803 glass powder manufactured by Nippon Electric Glass Co., Ltd., average particle size 2.5 μm) for obtaining adhesive strength to CuO powder (average particle size 3 μm). An organic binder, ethyl cellulose, was added together with a vehicle dissolved in terpineol, 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 that does not sinter is produced by using titanium oxide (Kanto Kagaku Co., Ltd., average particle size: 1.5 μm) powder, and glass frit (Corning Japan borosilicate aluminum glass softening point: 928 ° C.) as an inorganic component. 1
733 with an average particle size of 2.5 μm) added,
A green sheet having the same green sheet composition as the glass / ceramic substrate green sheet was prepared in the same manner. The thickness of the substrate green sheet is about 200.
μm, and the alumina green sheet is about 200 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. This step was performed without pressing the laminate. The first is a binder removal step. The organic binders of the green sheet and CuO paste used in this example 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 250 ° 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 carried out in pure nitrogen in a mesh belt furnace at 950 ° C. (At this time, firing is 880
C. is held for about 10 minutes and 950.degree. C. is held for about 12 minutes to perform two-stage sintering. ) There is a sintered body after suppressing shrinkage of the ceramic substrate on both surfaces of the laminated body produced as described above, but this could also be easily removed as in Example 1. When the shrinkage rate of the ceramic laminate was evaluated, the shrinkage was 0.05% or less.

Also in this example, when the uppermost layer was printed and baked using copper paste, a good low temperature sintered multilayer substrate was obtained.

In this example, Al ₂ O ₃ and TiO ₂ were used as the inorganic components of the green sheet for suppressing the shrinkage during firing of the ceramic substrate.
The same effect can be obtained by using rO ₂ , BeO and BN,
GA-33 and # 1733 are used for the glass material,
The same effect can be obtained as long as it does not crystallize at the required crystallization temperature of the glass-ceramic substrate, but crystallizes later. Further, since the green sheet layers that suppress shrinkage during firing of the ceramic substrate are formed on both sides, the same effect can be obtained without applying a weight to the laminated body.

Although the formation of the uppermost layer pattern was performed after firing the substrate, even if the uppermost layer paste is printed on the green sheet and simultaneously fired, the glass or the glass-ceramic mixture for suppressing shrinkage is sintered. It is needless to say that the ceramic multilayer substrate which can be easily removed and is in a good non-shrink state can be obtained because it is raised.

As described above, according to the present invention, in the process of manufacturing a multilayer ceramic substrate, both surfaces of the glass or the green sheet layer made of glass and ceramic which does not sinter at the temperature for crystallizing the inner layer glass-ceramic laminate are crystallized. When the substrate is fired, a multilayer substrate is obtained in which shrinkage due to sintering does not occur in the planar direction at all. Further, the green sheet layers provided on both sides start crystallization after the crystallization of the inner glass / ceramic laminate and start sintering, so that the sintered products on both sides can be easily removed after the firing is completed.

[0038]

As is clear from the above description,
INDUSTRIAL APPLICABILITY The present invention provides a multilayer substrate in which a glass-ceramic substrate shrinks only in the thickness direction during firing and does not shrink in the planar direction. The glass laminated on both sides is used for suppressing the shrinkage in the planar direction of the multilayer substrate. Alternatively, the mixture of glass and ceramic can be easily removed because it has shrunk after sintering and is contracted, and finally a multilayer substrate in a good state can be obtained.

As a result, the substrate material used for the multilayer substrate,
Substrates of the same size can always be obtained regardless of the green sheet composition and powder lot.

Similarly, in the production of the multilayer ceramic substrate, even if the inner 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.

Further, it is economical because the number of screen plates is small and it is not necessary to back-calculate the shrinkage factor and expand the inner layer pattern in the substrate design.

Further, the laminates on both sides, which need to be removed after the completion of firing, can be easily removed, the working time can be shortened, and the work can be simplified.

As described above, the present invention solves the problem of shrinkage error, which is the greatest problem of the green sheet laminating method,
This is an effective invention that facilitates the work process.

[Brief description of drawings]

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

[Explanation of symbols]

1 glass / ceramic green sheet layer 2 green sheet layer that suppresses shrinkage during firing of glass / ceramic substrate 3 internal electrode layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiko Hakotani 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Yoshifumi Nakamura, Kabushi 1006 Kadoma, Osaka Prefecture

Claims (9)

[Claims] 1. Crystallization of the glass-ceramic on both surfaces of a green-sheet laminate in which a plurality of green sheets made of glass-ceramic containing at least an organic binder and a plasticizer having an electrode pattern formed of a conductor paste composition are laminated. Crystallization does not occur at a temperature, but after the glass or the glass that begins to crystallize and sinters at the crystallization end temperature of the glass / ceramic or a green sheet made of a glass and ceramic mixture is laminated, a baking treatment is performed to A method of manufacturing a multilayer ceramic substrate, characterized in that the glass-ceramic sintered body is removed after the sintering of the laminated green sheets is completed. 2. The firing treatment is carried out by removing the binder, holding at the crystallization temperature of the glass-ceramic composition of the inner layer, and further up to the crystallization temperature of the glass or the glass and ceramic mixture laminated on both sides. The method for manufacturing a multilayer ceramic substrate according to claim 1, wherein the temperature is raised. 3. The conductor paste is Ag, Ag / Pd, Ag /
2. The method for manufacturing a multilayer ceramic substrate according to claim 1, wherein one of Pt and Cu is a main component. 4. A green sheet laminate comprising a plurality of green sheets made of glass-ceramic containing at least an organic binder and a plasticizer having an electrode pattern formed of a conductor paste composition containing cupric oxide as a main component. Laminated on both sides of the glass, glass that does not crystallize at the crystallization temperature of the glass / ceramic and that begins to crystallize at a temperature above the crystallization end temperature of the glass / ceramic and sinters, or a glass and ceramic mixture. After that, these are heat-treated in air at a temperature at which the organic binder inside the multilayer decomposes and scatters, and then undergoes reduction heat treatment in an atmosphere of hydrogen or a mixed gas of hydrogen and nitrogen. After sintering the body in a nitrogen atmosphere, and after finishing the sintering of the green sheets laminated on both sides Method for manufacturing a multilayer ceramic substrate characterized in that to remove the sintered body. 5. The firing treatment is carried out by holding at the crystallization temperature of the glass-ceramic composition of the inner layer and further raising the temperature to the crystallization temperature of the glass or the glass and ceramic mixture laminated on both surfaces. The method for manufacturing a multilayer ceramic substrate according to claim 4, wherein the multilayer ceramic substrate is manufactured. 6. Crystallization by firing is 850 ° C. to 1100 ° C.
The method for producing a multilayer ceramic substrate according to claim 1 or 4, wherein a green sheet made of glass or a glass / ceramic mixture occurring in the range of (4) is used for laminating both surfaces of the inner glass / ceramic laminate. 7. The method for producing a multilayer ceramic substrate according to claim 1, wherein the firing temperature is in the range of 800 ° C. to 1100 ° C. 8. A glass to be laminated on both sides, or a mixture of glass and ceramic, which is selected from the group consisting of aluminum borosilicate crystallized glass and lead borosilicate crystallized glass, or Al ₂ O ₃ as a ceramic material. , Mg
5. The method for producing a multilayer ceramic substrate according to claim 1, containing at least one of O, ZrO ₂ , TiO ₂ , BeO and BN. 9. The firing process according to claim 1, wherein the green sheet laminate is fired by applying pressure during the firing treatment.
A method for manufacturing the multilayer ceramic substrate according to.