JPH1084056A - Manufacture of ceramic board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ceramic board which is high in dimensional accuracy and uniform in plane structure by a method wherein a green sheet as a restraining layer containing slow-baking ceramic powder is laminated on both sides of a board green sheet which contains ceramic powder respectively, and the above laminate is baked under a high pressure applied in the direction of its thickness. SOLUTION: A restraining green sheet 12 which contains slow-baking ceramic powder is laminated on both sides of a board green sheet 11 which contains ceramic powder for the formation of a laminate, and the laminate is formed into a green sheet laminate 10 by thermocompression. Thereafter, the laminate 10 is subjected to a degreasing process in a oxidizing atmosphere to decompose and remove organic components contained in it and baked as it is pressed in its thickness wise direction with a high pressure to be elongated in a plane direction. By this setup, board green sheets are restrained form being shrunk in their plane direction and, on the contrary, the green sheets are elongated in their plane direction and restrained from varying in dimensions after baking. Board green sheets are flattened before baking and enhanced in evenness and dimensional accuracy after baking.

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 ceramic substrate, and more particularly, to a method for manufacturing a ceramic substrate used for an IC package for mounting a semiconductor element or the like.

[0002]

2. Description of the Related Art In order to protect a semiconductor device and at the same time to connect with a wiring formed on a motherboard, the semiconductor device is mounted on various packages. Among these packages, ceramic packages (ceramic substrates) have high reliability because of their excellent thermal conductivity, moisture resistance, heat resistance, and the like, and are used in many fields.

[0003] In recent years, with high integration of semiconductor elements, the performance and miniaturization of electronic devices have been rapidly progressing, and the method of mounting the semiconductor elements in a package has been changed from the conventional mounting method by wire bonding. The mounting method by flip chip bonding, which is suitable for multi-chip and high-density mounting, has been changed. Also, with the increase in control speed and signal processing speed of electronic devices, noise at the time of switching has become a problem, and ceramic substrates provided with capacitors have been used to absorb the switching noise. I have.

As a substrate used for the above-mentioned applications, a glass ceramic substrate using a glass which can be fired at a low temperature has attracted attention. This glass ceramic substrate is 800-10
Since it can be fired at a low temperature of about 00 ° C., Ag,
Simultaneous firing with a low-resistance wiring material such as Cu can be performed,
Low dielectric constant, low dielectric loss, thermal expansion coefficient of Si
Therefore, no problem occurs even when the semiconductor elements are connected by flip-chip bonding, which is suitable for applications such as flip-chip substrates. This glass ceramic substrate has been conventionally manufactured by the following method. First, a glass powder such as borosilicate glass and an aggregate powder such as alumina are mixed, and then a resin, a solvent, a plasticizer, etc. are added and mixed to prepare a slurry, and the doctor blade method is performed using the slurry. A green sheet is produced by the above method.

Next, after cutting these green sheets into a predetermined size, the green sheets are subjected to a processing such as punching according to the shape of each laminated portion and the like, and Ag
A via paste is filled in the via hole with a conductive paste mainly containing Cu or Cu or the like, and a conductive paste layer having a predetermined pattern is formed on the surface. Next, a ceramic substrate is manufactured by laminating a plurality of green sheets that have been subjected to the above processing, pressing and integrating the green sheets, performing binder removal processing, and firing. When a noise absorbing capacitor is incorporated in a ceramic substrate, a paste layer or a green sheet for forming a capacitor containing dielectric powder that can be fired at a similar temperature (a conductor paste layer for electrodes is formed on both sides). Is formed inside the substrate green sheet.

The glass ceramic substrate manufactured by the above method shrinks during the firing process, and the shrinkage is as large as about 20%. Further, when the conductive paste layer is formed inside the green sheet, the shrinkage differs between the conductive paste layer and the green sheet, so that the glass ceramic substrate is likely to warp or undulate. Also, in addition to the warpage and undulation, the shrinkage rate is affected by subtle changes in the firing conditions and the like, so that the dimensions vary. In a flip chip substrate, a conductor layer for flip chip bonding is formed, so high dimensional accuracy is required, and it is difficult to satisfy the requirements for dimensional accuracy by a normal firing method.

Conventionally, as a means for improving the dimensional accuracy of a ceramic substrate, various methods for suppressing shrinkage of a green sheet laminate in the surface direction during firing have been proposed. In Japanese Patent Publication No. 5-22671, a wall through which gas can flow in and out is opposed to both surfaces of a ceramic green sheet, pressure is applied through the wall in the thickness direction of the ceramic green sheet, and gas flows in from the wall. Alternatively, a method is disclosed in which the ceramic green sheet is fired while flowing. The publication describes that by applying mechanical pressure or gas pressure from the thickness direction, it is possible to suppress warpage, distortion, shrinkage, and the like of the sintered body.

[0008] Japanese Patent Publication No. 5-503498 discloses that
A method is disclosed in which a flexible and removable release layer containing a nonmetallic inorganic powder is laminated on both surfaces of a green sheet, and firing is performed while applying pressure in the thickness direction of the laminate. According to the above method, since pressure is applied in the thickness direction at the time of firing, shrinkage in the plane direction is suppressed. As a result, variation in shrinkage is reduced, and the occurrence of warpage and the like is also suppressed. Since the non-metallic inorganic powder does not sinter even after firing, even if it adheres to a sintered body, the release layer can be removed with a light force.

[0009]

However, in the method disclosed in Japanese Patent Publication No. 5-22671, the ceramic green sheet is pressed so as not to be deformed.
And special parts for inflow or outflow of gas are required, and inflow or outflow of gas during firing,
There was a problem that its thermal efficiency was low.

In the method disclosed in Japanese Patent Application Laid-Open No. 5-503498, the aim is to suppress the shrinkage of the green sheet in the plane direction at the time of firing, so that an excessively large pressure is applied so that the green sheet is not deformed. Not. Therefore, the green sheet is not firmly held by the release layer, and there are a part receiving a pressure close to the pressure applied to the green sheet and a part not receiving much pressure, which is caused by the non-uniformity of the pressure. Thus, there is a problem that the shrinkage varies depending on the location of the sintered body, and the dimensional accuracy of the sintered body is reduced.

The present invention has been made in view of the above problems, and provides a method of manufacturing a ceramic substrate capable of manufacturing a ceramic substrate having a high dimensional accuracy (positional accuracy) and a uniform structure in a plane direction. It is an object.

[0012]

According to the present invention, there is provided a method for manufacturing a ceramic substrate (1), wherein a constraining layer containing a non-sinterable ceramic powder is provided on both surfaces of a substrate green sheet containing a ceramic powder. By stacking green sheets for use and firing while applying a high pressure in the thickness direction of the laminated body, a sintered body extending in the surface direction more than the green sheet for a substrate before firing is manufactured.

According to the method (1) for producing a ceramic substrate, since a high pressure is applied, pressure is uniformly applied to the entire surface of the green sheet, shrinkage due to firing can be prevented, and dimensional accuracy (positional accuracy) can be prevented. ) Can be manufactured.

Further, in the method (2) for manufacturing a ceramic substrate according to the present invention, in the method (1) for manufacturing a ceramic substrate, a conductive paste layer is formed inside and / or on a surface of the green sheet for the substrate. It is characterized by.

According to the above method (2) for producing a ceramic substrate, the conductor paste is also uniformly pressed.
Even if a conductor layer (metal layer) is formed on the surface or inside, a ceramic substrate having high dimensional accuracy (positional accuracy) such as a conductor layer can be manufactured.

The method (3) for manufacturing a ceramic substrate according to the present invention is the same as the method (1) or (2) for manufacturing a ceramic substrate, except that a paste layer or a green sheet for forming a capacitor is formed inside the green sheet for the substrate. Is characterized in that a layer containing is formed.

According to the method (3) for manufacturing a ceramic substrate, even pressure is applied to a paste layer for forming a capacitor and the like, and even if a capacitor is formed inside the ceramic substrate, dimensional accuracy (positional accuracy) is obtained. , A ceramic substrate having a high value can be manufactured.

Further, the method (4) for manufacturing a ceramic substrate according to the present invention includes the method (1) for manufacturing a ceramic substrate described above.
(3) The method according to (3), wherein the ceramic substrate is a glass ceramic substrate.

According to the method (4) for manufacturing a ceramic substrate, since the ceramic substrate to be manufactured is a glass ceramic substrate, it can be fired at a relatively low temperature, and a wiring material having a low conductivity can be used. In addition, since it does not easily react with the constraining layer green sheet, a glass ceramic substrate having higher dimensional accuracy (positional accuracy) can be manufactured.

Further, the method (5) for manufacturing a ceramic substrate according to the present invention includes the method (1) to the method (1) for manufacturing a ceramic substrate.
In any of (4), the hardly sinterable ceramic powder constituting the green sheet for the constraining layer is made of MgO, Al ₂ O.
₃ , ZrO ₂ , or stabilized ZrO ₂ .

According to the method (5) for producing a ceramic substrate, the hardly sinterable ceramic powder hardly reacts with the green sheet for the substrate, and does not sinter at the sintering temperature of the green sheet for the substrate. It can be easily removed from the ceramic substrate.

The method (6) for manufacturing a ceramic substrate according to the present invention comprises the steps (1) to (1) for manufacturing the ceramic substrate described above.
(5) In any one of (5), the thickness of the constraining layer green sheet is 0.30 mm or less.

According to the method (6) for manufacturing the ceramic substrate, the thickness of the constraining layer green sheet is reduced.
Excessive elongation of the green sheet for a substrate can be suppressed, the elongation by firing becomes in a more appropriate range, and dimensional variation can be suppressed.

Further, the method (7) for manufacturing a ceramic substrate according to the present invention includes the method (1) to the method (1) for manufacturing a ceramic substrate.
In any one of (6) and (1), the length of one side of the green sheet for a substrate before firing is equal to the length of the ceramic substrate after firing.
The elongation rate of the length of the side is 0.20% or less.

According to the method for manufacturing a ceramic substrate (7), since the elongation percentage of the fired ceramic substrate is set in the above-described appropriate range, the shape of the sintered body is not impaired and the sintered body is uniform in the in-plane direction. Further, a ceramic substrate having high dimensional accuracy can be manufactured.

The method (8) for manufacturing a ceramic substrate according to the present invention includes the method (1) to the method (1) for manufacturing a ceramic substrate.
(7) The method according to any one of (7), wherein a pressure applied in the thickness direction of the laminate during firing is 7.4 × 10 ⁵ Pa or more.

According to the method (8) for producing a ceramic substrate, the pressure applied in the thickness direction of the laminate during firing is 7.4.
Since the pressure is as high as × 10 ⁵ Pa or more, the elongation ratio of the ceramic substrate is sufficiently adjusted, and a ceramic substrate with high dimensional accuracy can be manufactured.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a ceramic substrate according to the present invention will be described below.

In the method of manufacturing a ceramic substrate according to the present invention, the type of ceramic substrate to be manufactured is not particularly limited, and specific examples thereof include oxide-based ceramic substrates such as an alumina ceramic substrate and a mullite ceramic substrate. Examples include a ceramic substrate, a glass ceramic substrate made of borosilicate glass containing cordierite or the like as an aggregate, and the like. In this embodiment, among these, in particular, a glass ceramic substrate which can be fired at a relatively low temperature, does not easily react with the constraining layer, and requires dimensional accuracy and flatness, for example, a glass ceramic substrate for a flip chip Are mainly manufactured. Therefore, in the following, a method for manufacturing a glass ceramic substrate will be described as an example.

In the method of manufacturing a ceramic substrate according to the embodiment, first, a green sheet for a substrate and a green sheet for a constraining layer are prepared and laminated.

A green sheet for a substrate containing a glass ceramic raw material powder as a main component can be produced by a method substantially similar to the method described in the section of “Prior Art”. For example, ceramic powder for a ceramic substrate, resin,
It is manufactured by molding a mixed slurry composed of an organic solvent, a plasticizer, and the like by a doctor blade method. The green sheet for a substrate is usually composed of a laminate of a plurality of green sheets, but it is not always necessary to laminate a plurality of individual green sheets into a laminate, and may be composed of a single-layer green sheet. The formation of the conductive paste layer on the sheet is also optional.

The substrate green sheet is composed of the raw material powder of the glass ceramic, a resin, an organic solvent, a plasticizer and the like. The raw material powder of the glass ceramic,
Borosilicate glass, cordierite (MgO-Al ₂ O
_3- SiO ₂ ) glass, anorthite (CaO-Al)
_It is a mixture of powder such as ₂ O ₃ —SiO ₂ ) -based glass and powder of aggregate such as Al ₂ O ₃ .
1 to 10 μm is preferred. Examples of the resin include acrylic resin, butyral resin and the like, and examples of the organic solvent include toluene and xylene.
Examples of the plasticizer include dibutyl phthalate and dioxyl phthalate. These mixing ratios are based on 100 parts by weight of the raw material powder of the glass ceramic.
30 to 50 parts by weight of an organic solvent, 1 to 5 parts by weight of a plasticizer,
The binder is preferably 5 to 15 parts by weight. When a conductive paste layer is formed on the green sheet, Ag, C
u, Au, Ag-Pd or the like is used as the conductor material.

When a capacitor for noise absorption is built in the ceramic substrate, a paste layer or a green sheet for forming a capacitor is laminated inside the green sheet for the substrate. Conductive paste layers for electrodes must be formed on both sides of the paste layer or the green sheet. Examples of the material for the capacitor include a BaTiO ₃ -based dielectric and an SrTiO ₃ -based dielectric, and the relative dielectric constant thereof is preferably about 3000.

A green sheet (a green sheet for a constraining layer) containing a non-sinterable ceramic powder to be laminated on both sides of the glass ceramic green sheet can be produced by a usual method for producing a green sheet.

It is preferable that the hardly sinterable ceramic powder does not easily react with the green sheet for the substrate and does not sinter at the firing temperature of the green sheet for the substrate. Specific examples include MgO and Al ₂ O. ₃ , ZrO
₂ , stabilized ZrO ₂ , mullite, SiO ₂ , AlN, B
N and the like, but when the glass component in the glass ceramic is basic, MgO or the like is preferable, and when the glass component is acidic, Al ₂ O ₃ , ZrO ₂ , stabilized ZrO ₂
Are preferred. The thickness of the constraining layer green sheet is preferably 0.30 mm or less in order to suppress the elongation of the fired ceramic substrate and keep the dimensional accuracy high. When the thickness of the constraining green sheet exceeds 0.30 mm, the constraining layer green sheet undergoes elongation due to pressure, whereby the elongation of the substrate green sheet also increases, and the elongation rate of the fired ceramic substrate increases. Therefore, the dimensional accuracy tends to decrease.

Examples of the organic solvent used for preparing the green sheet for the constraining layer include toluene and xylene, and examples of the plasticizer include dibutyl phthalate and dioxyl phthalate.
For example, butyral resin, acrylic resin and the like can be mentioned.
The mixing ratio of the organic solvent is 30 to 50 parts by weight, based on 100 parts by weight of the raw material powder of the non-sinterable ceramic powder,
The plasticizer is preferably 1 to 5 parts by weight, and the binder is preferably 5 to 15 parts by weight.

Next, the green sheets for the constraining layer are laminated on both sides of the green sheets for the substrate, and thermocompression-bonded to produce a green sheet laminate. Thereafter, a high pressure is applied in the thickness direction of the green sheet laminate to perform a degreasing step of decomposing and eliminating organic components in an oxidizing atmosphere while giving elongation in the surface direction of the green sheet laminate, followed by firing. . The pressure applied in the thickness direction of the green sheet laminate is preferably 7.4 × 10 ⁵ Pa or more, and 9.8.
× 10 ⁵ Pa or more is more preferable. If the pressure applied in the thickness direction of the green sheet laminate is less than 7.4 × 10 ⁵ Pa, the dimensional variation tends to increase. Further, the temperature in the degreasing step is preferably about 200 to 600 ° C, and the firing temperature is preferably about 800 to 1000 ° C. Since the green sheet laminate is densified due to high pressure and the resin and the solvent are not easily decomposed in the degreasing step, it is desirable to perform degreasing for a sufficient time while sufficiently flowing gas.

By adopting the above method, shrinkage in the plane direction does not occur during sintering of the green sheet for a substrate, but the sheet elongates slightly in the plane direction, and the dimensional variation after firing can be suppressed. In addition, by applying a high pressure, the green sheet for a substrate before firing is further flattened, so that the flatness of the substrate after firing is also increased. Since the elongation rate varies depending on the type of glass ceramic to be sintered, it cannot be unconditionally determined, but the elongation rate of the length of one side of the ceramic substrate after firing with respect to the length of one side of the green sheet for the substrate before firing. 0.20%
It is preferably at most, more preferably 0.01 to 0.08%. Generally, the elongation after firing is substantially constant regardless of the material of the constraining layer.

According to the above method, the dimensional variation of the manufactured ceramic substrate can be suppressed, and the dimensional accuracy can be improved. In particular, the thickness of the constraining layer green sheet is set to 0.30 mm or less, or the pressure applied in the thickness direction of the green sheet laminate is 7.4 × 10 ⁵ Pa.
As described above, the dimensional variation of the ceramic substrate is reduced to 0.
Can be controlled within 2%, and dimensional accuracy is ± 10μm
/ 10 mm or less. In addition, the flatness of the ceramic substrate can be suppressed to within 10 μm / 10 mm. Here, the dimensional variation refers to, for example, ｛(actual size−set size) / set size｝ × 100 (%) with respect to the size between wirings. The flatness is 10 mm
The difference between the lowest part and the highest part when the unevenness is measured for the straight line is indicated as A μm / 10 mm.

[0040]

Examples and Comparative Examples Hereinafter, examples of the method for manufacturing a ceramic substrate according to the present invention will be described.

[0041] <Example> (1) Formulation glass material powder for a green sheet glass ceramic raw material powder for _{substrate: CaO-Al 2 O 3 -SiO} 2 -B 2
O ₃ glass Aggregate powder: Alumina Mixing ratio: Glass material powder: 60 parts by weight, Alumina powder: 40 parts by weight Preparation of slurry: Toluene as an organic solvent in glass ceramic raw material powder, dioxyl phthalate as plasticizer,
Preparation of Green Sheet for Wet Mixing Substrate with Addition of Acrylic Resin as Binder (i) After preparing the sheet by a doctor blade method, it is cut into a predetermined size. (ii) Via holes are formed by punching, and the Ag conductor paste is filled in the via holes. (iii) A conductive paste layer is formed on the surface of the green sheet by screen printing.

(2) Preparation of Green Sheet Slurry for Constraint Layer Alumina powder (average particle size: 0.5 μm) as a non-sinterable ceramic powder, toluene as an organic solvent, dioxyl phthalate as a plasticizer, and an acrylic resin as a binder Use wet mixing. Preparation of green sheet for constraining layer A green sheet was prepared in the same manner as in (1).

(3) Production of Green Sheet Laminate As shown in FIG. 1, a green sheet 12 for a constraining layer was laminated on both sides of a green sheet 11 for a substrate, and 9.8 × 10
^The green sheet laminate 10 was produced by thermocompression bonding at a pressure of ⁶ Pa.

(4) Degreasing the green sheet laminate 10
4. Pressure in the thickness direction of the fired green sheet laminate 10:
0 × 10 ⁵ to 9.8 × 10 ⁵ Pa Degreasing conditions Temperature: 600 ° C., time: 1 hour, atmosphere: air atmosphere Firing conditions Temperature: 900 ° C., time: 10 minutes, atmosphere: air atmosphere <Evaluation> The dimensions (including the dimensions of the conductor layer pattern) of the ceramic substrate were measured, and the difference from the set value was compared to calculate the dimensional variation. The results are shown in Table 1 below.

[0045]

[Table 1]

As is clear from Table 1, a ceramic substrate manufactured by applying a high pressure in the thickness direction of the green sheet laminate 10 and performing a degreasing treatment and a sintering treatment does not shrink but elongates. And the dimensional variation is small. In particular, when the thickness of the green sheet for the constraining layer is 0.30 mm or less and the pressure is 7.4 × 10 ⁵ Pa or more, the dimensional variation is as small as 0.2% or less. The dimensional variation was significantly improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a laminated state of a green sheet laminate before firing in a method of manufacturing a ceramic substrate according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 green sheet laminate 11 green sheet for substrate 12 green sheet for constraining layer

Claims (8)

[Claims] 1. A green sheet for a constraining layer containing a non-sinterable ceramic powder is laminated on both sides of a green sheet for a substrate containing a ceramic powder, and fired while applying high pressure in the thickness direction of the laminate. A method of manufacturing a ceramic substrate, comprising: manufacturing a sintered body extending in a plane direction from a green sheet for a substrate before firing. 2. The method for producing a ceramic substrate according to claim 1, wherein a conductive paste layer is formed inside and / or on the surface of the substrate green sheet. 3. The method for manufacturing a ceramic substrate according to claim 1, wherein a paste layer for forming a capacitor or a layer containing a green sheet is formed inside the green sheet for a substrate. 4. The method for manufacturing a ceramic substrate according to claim 1, wherein the ceramic substrate is a glass ceramic substrate. 5. The ceramic powder constituting the constraining layer green sheet is characterized by containing at least one of MgO, Al ₂ O ₃ , ZrO ₂ and stabilized ZrO _2. The method of manufacturing a ceramic substrate according to claim 1. 6. The thickness of the constraining layer green sheet is 0.3.
The method for manufacturing a ceramic substrate according to claim 1, wherein the thickness is 0 mm or less. 7. The elongation percentage of the length of one side of the ceramic substrate after firing to the length of one side of the green sheet for substrate before firing is 0.20% or less.
7. The method for manufacturing a ceramic substrate according to any one of Items 6 to 6. 8. The method for manufacturing a ceramic substrate according to claim 1, wherein the pressure applied in the thickness direction of the laminate during firing is 7.4 × 10 ⁵ Pa or more.