JP2727700B2 - Method for manufacturing multilayer ceramic circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] Regarding the configuration of a multilayer ceramic circuit board, an object of the present invention is to provide a multilayer ceramic circuit board having a reduced signal delay time and excellent mechanical strength. In forming the signal line, a green sheet made of crystallized glass having a large glass component or a low crystallization rate is used for the signal line forming region (6), and a ceramic layer is used for the reinforcing layer region (11) requiring mechanical strength. A plurality of green sheets made of crystallized glass having a high content or a high crystallization rate are used, and the crystallization rate of the ceramic component or the crystallized glass of the crystallized glass is maximized at the center of the reinforcing layer region (11). A method of manufacturing a multilayer ceramic circuit board is characterized by laminating a green sheet having a composition ratio gradually changed, followed by pressing and firing.

[Industrial applications]

The present invention relates to a method for manufacturing a multilayer ceramic circuit board having a reduced signal delay time and excellent mechanical strength.

Due to the need to process a large amount of information at high speed, information processing apparatuses have been reduced in size and capacity, and the apparatuses are mounted with a large number of semiconductor elements such as LSIs and VLSIs, and are mounted at high density.

Here, although a large number of the above semiconductor elements are mounted on the printed wiring board, the heat generation of the LSI chip is about 4 W and the heat generation of the VLSI chip is about 10 W due to the improvement in the degree of integration. Therefore, printed wiring boards need to be excellent in heat resistance.
Ceramics such as ₂ O ₃ ) are used as substrate materials.

Further, since a semiconductor element has a large number of lead terminals, three-dimensional wiring is required, and a multi-layer circuit board is used for that purpose.

[Conventional technology]

The prerequisites for the multilayer ceramic circuit board are that it has excellent heat resistance, and that the conductor resistance of the electronic circuit is low and that the signal delay time is short.

Here, alumina ceramics have excellent heat resistance and thermal conductivity. However, since the firing temperature is as high as about 1700 ° C., only a high melting point metal such as tungsten (W) can be used as a conductor line.

However, in that case, the conductor resistance is high and the signal transmission loss increases, so that it is not suitable as a transmission line.

Therefore, as a constituent material of the multilayer ceramic circuit board, a glass ceramic that can use copper (Cu) as a conductor line is used.

That is, the firing temperature of glass ceramics can be set to 1000 ° C. or less, and therefore, a metal material having excellent conductivity such as gold (Au) or Cu can be used.

FIG. 2 shows the structure of a conventional multilayer ceramic circuit board using glass ceramics. A shield layer 2 and a signal line 3 are screen-printed on a glass ceramic green sheet 1 using a conductive paste such as Cu. The multilayer ceramic circuit board 4 is obtained by aligning, laminating, integrating by pressing and firing.

Here, a typical glass ceramic is composed of a borosilicate glass to which alumina powder is added, and since it is made of a microcrystalline polymer, its mechanical strength, for example, its bending strength is high.
150 to 200 MPa, which is significantly improved compared to glass. Dielectric constant is 5 to 9 and dielectric constant of borosilicate glass (about 4).
Higher than this, which is a problem.

That is, although the frequency of a signal extends to light due to the speeding up of information processing, the multilayer circuit board on which an electronic circuit for processing such a high-speed signal is formed has a delay time τ of an electric signal as small as possible. In addition, it is necessary that the crosstalk between the wirings is small, and for that purpose, the dielectric constant ε of the used substrate needs to be small.

τ = ε ^1/2 / c (1) where c is the speed of light. Therefore, it was necessary to reduce the dielectric constant.

[Problems to be solved by the invention]

Multilayer ceramic circuit boards using glass ceramics as substrate materials are converted to green sheets made of glass ceramics.
It is made by screen printing copper paste to make conductor lines, drying, laminating green sheets, pressing and integrating and firing.

However, the multilayer ceramic circuit board manufactured in this way has a high dielectric constant, so that the signal delay becomes large and high-speed propagation becomes difficult.

On the other hand, a multilayer ceramic circuit board having a reduced content of ceramics has a low dielectric constant and is suitable for high-speed signal propagation, but has a problem in that it has low mechanical strength and is easily broken.

[Means for solving the problem]

The above problem is caused by forming a multi-layer ceramic circuit board, using a green sheet made of crystallized glass having a large glass component or a low crystallization rate in a signal line forming area, and using a green sheet made of crystallized glass having a low crystallization rate in a reinforced layer area requiring mechanical strength. Uses a plurality of green sheets made of crystallized glass with a large amount of ceramic components or a high crystallization rate, and in such a way that the crystallization rate of the contained ceramic component or the crystallized glass is maximized at the center of the reinforced layer region. The problem can be solved by a method of manufacturing a multilayer ceramic circuit board, characterized by laminating green sheets having gradually changed composition ratios, and firing by pressing.

[Action]

The present invention uses a low dielectric constant green sheet in a signal line forming area where a signal line and a shield layer are present among a large number of glass ceramic green sheets constituting a multilayer ceramic circuit board. A glass ceramic green sheet with high mechanical strength is laminated in the reinforcing layer area connecting the line forming area, and in this case, the glass ceramic green sheet in the center is configured to have the highest mechanical strength. It is.

FIG. 1 is a cross-sectional view showing a configuration method of a multilayer ceramic circuit board according to the present invention.
There is a shield layer 2 with a dielectric layer 5 interposed therebetween to form a signal line forming region 6.

Then, a second dielectric layer 7 and a third dielectric layer
8, the fourth dielectric layer 9, the fifth dielectric layer 10, the fourth dielectric layer
9, a third dielectric layer 8, a second dielectric layer 7, and a plurality of dielectric layers are sequentially laminated to form the reinforcing layer region 11. In this case, the central dielectric layer (in this example, In the case, the fifth dielectric layer 1
The composition of the raw glass ceramics is sequentially changed so that 0) has the highest mechanical strength.

Here, the reason for gradually changing the composition of the raw material is to prevent the occurrence of delamination during firing of the substrate or mounting of the semiconductor element due to the difference in thermal expansion coefficient and contraction rate between the respective dielectric layers.

As described above, according to the present invention, the signal line forming region 6 where the shield layer 2 is provided around the signal line 3 is formed using glass ceramics having a low dielectric constant, and the reinforcing layer connecting the two signal line forming regions 6 is formed. The region 11 is formed by using a plurality of glass ceramic layers so that the central portion has the highest mechanical strength.

By adopting such a configuration, it is possible to form a multilayer ceramic circuit board with little signal delay, excellent mechanical strength, and no delamination.

〔Example〕

Example 1: Mullite (3Al ₂ O ₃ · 2SiO ₂ ) as ceramics
And borosilicate glass (abbreviated as B glass) and quartz glass (abbreviated as S glass) were used as the glass.

In addition, polymethyl methacrylate (abbreviation: PMMA) was used as a binder, dibutyl phthalate (abbreviation: DBP) was used as a plasticizer, and ethyl alcohol and acetone were used as solvents. These raw materials were mixed with the composition shown in Table 1. Then, a dielectric material having a small dielectric constant (No. 1) and a dielectric material having a gradually increased mechanical strength (No. 2 to No. 5) were prepared.

The raw materials of the respective compositions were kneaded with a ball mill for 20 hours, and the resulting slurry was subjected to a doctor blade method to form a signal line forming region having a low dielectric constant and having a low dielectric constant.
The composition of the above makes a green sheet of 200 μm thickness,
In addition, those having compositions of Nos. 2 to 5 which form a reinforcing layer region having a high mullite content and excellent mechanical strength formed a green sheet having a thickness of 50 μm.

These green sheets were cut into 100 mm square, punched to form via holes, and then filled with copper paste in the holes.

Next, a signal paste and a shield layer were formed by screen-printing copper paste on a green sheet forming a signal line formation region.

Next, the respective green sheets were aligned and laminated in the order shown in FIG.

 Here, the green sheet of No. 1 composition is in the first dielectric layer, the green sheet of No. 2 composition is in the second dielectric layer, and the green sheet of No. 3 composition is in the third dielectric layer. The green sheet of the composition No. 4 corresponds to the fourth dielectric layer, and the green sheet of the composition No. 5 corresponds to the fifth dielectric layer.

Then, after being integrated under pressure at a temperature of 100 ° C. and 20 MPa, it was fired in a nitrogen (N ₂ ) stream at 1000 ° C. for 5 hours to complete a multilayer ceramic circuit board.

Table 2 shows that the multilayer ceramic circuit board according to the present invention has the signal delay time, the bending strength and the effective dielectric constant of the multilayer ceramic circuit board according to the present invention. This is a comparison with a circuit board.

As described above, the multilayer ceramic circuit board obtained by implementing the present invention has a small signal delay time and a large bending strength.

Example 2: Using a glass raw material having the composition shown in Table 3, a glass having a low crystallization ratio and a low dielectric constant, and a glass having excellent mechanical properties. Had made.

Here, PMMA is used as the binder, and DB is used as the plasticizer.
P, and ethyl alcohol and acetone as solvents. These materials are mixed with the composition shown in Table 3 to obtain a dielectric material with a small dielectric constant (No. 1) and a dielectric material with a gradually increasing mechanical strength. Body materials (No. 2 to No. 5) were prepared.

This glass material, a binder, a plasticizer and a solvent 43: 8:
The materials having the respective compositions were mixed at a weight ratio of 4:45, and kneaded with a ball mill for 20 hours using a ball mill, and the resulting slurry was subjected to a doctor blade method to reduce the dielectric constant and form a signal line forming region. The composition of No. 2 to 5 has a composition of No. 2 to 5 which forms a green sheet with a thickness of 200 μm, and has a high content of TiO ₂ as a nucleation product and forms a reinforcing layer region having excellent mechanical strength. The product formed a green sheet having a thickness of 50 μm.

These green sheets were cut into 100 mm square, punched to form via holes, and then filled with copper paste in the holes.

Next, a signal paste and a shield layer were formed by screen-printing copper paste on a green sheet forming a signal line formation region.

Next, the respective green sheets were aligned and laminated in the order shown in FIG.

 Here, the green sheet of No. 1 composition is in the first dielectric layer, the green sheet of No. 2 composition is in the second dielectric layer, and the green sheet of No. 3 composition is in the third dielectric layer. The green sheet of the composition No. 4 corresponds to the fourth dielectric layer, and the green sheet of the composition No. 5 corresponds to the fifth dielectric layer.

Then, after being integrated under pressure at a temperature of 100 ° C. and 20 MPa, it was fired in a nitrogen (N ₂ ) stream at 1000 ° C. for 5 hours to complete a multilayer ceramic circuit board.

Table 4 shows the signal delay time, bending strength, and effective dielectric constant of the multilayer ceramic circuit board according to the present invention obtained in this manner, which are made of crystallized glass of a single composition of No. 1 and No. 5, respectively. It is a comparison.

As described above, the multilayer ceramic circuit board obtained by implementing the present invention has a small signal delay time and a large bending strength.

〔The invention's effect〕

As described above, by implementing the present invention, a multilayer ceramic circuit board having a small signal delay time, excellent mechanical strength, and free from delamination during a working process or during use can be put to practical use. .

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing the configuration of a multilayer ceramic circuit board according to the present invention, and FIG. 2 is a partial sectional view showing the configuration of a conventional multilayer ceramic circuit board. In the figure, 2 is a shield layer, 3 is a signal line, 5 is a first dielectric layer, 6 is a signal line forming region, 7 is a second dielectric layer, 8 is a third dielectric layer, and 9 is a Reference numeral 4 denotes a dielectric layer, 10 denotes a fifth dielectric layer, and 11 denotes a reinforcing layer region.

Claims (2)

(57) [Claims] In forming a multilayer ceramic circuit board,
For the signal line forming area (6), a green sheet containing a large amount of glass component is used, and a reinforcing layer area (11) requiring mechanical strength is used.
Use multiple green sheets with many ceramic components for
Manufacturing a multilayer ceramic circuit board, characterized by laminating green sheets in which the composition ratio is gradually changed so that the contained ceramic component is maximized in the central portion of the reinforcing layer region (11), and firing by pressing. Method. 2. A method for forming a multilayer ceramic circuit board, comprising:
A green sheet made of crystallized glass having a low crystallization rate is used for the signal line forming area (6), and a plurality of glass sheets made of crystallized glass having a high crystallization rate are used for the reinforcing layer area (11) requiring mechanical strength. And the reinforcing layer region (11)
A method of manufacturing a multilayer ceramic circuit board, comprising: laminating green sheets whose composition ratios are gradually changed so that the crystallization ratio of glass is maximized in a central portion of the glass sheet, followed by firing under pressure.