JPH06164142A - Method for manufacturing multilayer wiring board - Google Patents

Abstract

(57) [Abstract] [Purpose] By using a green sheet having an uneven distribution layer containing a large amount of binder, it becomes easy to produce a laminate having excellent lamination adhesion between the green sheets, and by sintering this, Provided is a method for producing a dense and highly reliable multilayer wiring board which does not cause defects such as peeling, blistering, and cracking between layers. [Structure] A green sheet 1 having an uneven distribution layer 7 containing a large amount of a binder 3 near the surface of the green sheet is used. The amount of binder of the uneven distribution layer 7 is 24% or more of the amount of added binder that is present in the surface layer when the green sheet 1 is divided into five equal parts in the thickness direction. Further, in the drying process by the doctor blade method, the solvent content rate in the green sheet 1 is 10
The drying temperature up to 0 to 50% is 40 ° C or higher.

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 wiring board, and relates to reliability for preventing defective lamination adhesion of a multi-layer wiring board obtained by stacking and sintering green sheets having conductor wiring. The present invention relates to a method for manufacturing a high-performance multilayer wiring board.

[0002]

2. Description of the Related Art Generally, a multilayer wiring board is obtained by laminating and sintering green sheets having conductor wiring. First, after adding additives such as ceramic particles, a binder, a solvent and a dispersant with a ball mill to obtain a uniform slurry,
A green sheet is obtained by making this into a sheet on a polyester film by the doctor blade method. In this green sheet, the surface in contact with the polyester film (back surface) is likely to be flattened by the binder exuding due to the capillary phenomenon between the ceramic particles and the polyester film. On the other hand, the surface (surface) that was in contact with the blade is dried in a free state,
The binder involved in the adhesion is small on the surface of the ceramic particles, and irregularities having the width of the particle size distribution of the particles used are formed.

Such green sheets are subjected to through-hole processing, hole filling with conductors and wiring printing, and several tens of green sheets having these conductor wirings are stacked and pressure is applied while heating to form a laminate. . At this time, the front surface side having unevenness and less binder was inferior in adhesiveness to the flat back surface side. A multilayer wiring board can be obtained by sintering the laminated body of the green sheets. However, if the green sheet density is low, there are pores between the particles, and the packing state of the particles is coarse (large porosity). For example, there is a problem that the green sheet warps due to shrinkage after sintering.

If there is a poor adhesion between the layers of the laminate, the layers may be peeled off or bulged during sintering, causing a disconnection in the internal conductor. Therefore, conventionally, for example, JP-A-58
As described in JP-A-955641, a binder having good adhesiveness is used, and as described in JP-A-3-283496, the amount of the binder added is increased, the pressure is increased, and a solvent is applied to the surface of the green sheet. Was attempted to avoid the adhesion failure between layers by applying.

[0005]

In the above-mentioned prior art, the binder having good adhesiveness described in JP-A-58-95641 has other characteristics such as interaction with ceramic particles, workability and binder removal property. If taken into consideration, it may not always be reliable to use. In addition, JP-A-3-283496
In the technique described in the publication, when the amount of binder added is increased, the binder removal property in the subsequent sintering process deteriorates, and the characteristics of the sintered body deteriorate. Further, when the pressure bonding pressure is increased, the deformation of the wiring layer becomes a problem. In the case of solvent coating, sufficient consideration has not been given to problems such as bleeding of wiring conductors, swelling, and deformation of green sheets.

The present invention has been made to solve the above-mentioned problems of the prior art, and by using a green sheet having an uneven distribution layer containing a large amount of a binder, a laminate having excellent lamination adhesion between the green sheets. Facilitate the production of
It is an object of the present invention to provide a dense and highly reliable method for producing a multilayer wiring board, which is free from defects such as peeling between layers, swelling, and cracks by sintering this.

[0007]

In order to achieve the above object, the structure of the method for producing a multilayer wiring board according to the present invention comprises at least ceramic particles, a binder and a solvent,
In a method for manufacturing a multilayer wiring board, in which green sheets having conductor wiring are laminated and sintered, a green sheet having an uneven distribution layer containing a large amount of a binder is used near the surface of the green sheet.

More specifically, the binder amount of the uneven distribution layer is 24% or more of the added binder amount in the surface layer when the green sheet is divided into five equal parts in the thickness direction, and the surface of the green sheet is The neighborhood means the surface of the ceramic particles existing on the outermost surface of the green sheet to a thickness corresponding to 1/5 of the green sheet in the thickness direction.

Further, the particle packing rate of the green sheet per unit volume is 40% to 70%, and the particle packing rate of the portion where the binder is unevenly distributed is also 40% to 70%, and the particle packing rate is the same. Are equal in the thickness direction, and the porosity per unit volume of the portion where the binder is unevenly distributed is smaller than the porosities of the other portions.
Further, the green sheet is manufactured by the doctor blade method, and in the drying step, the drying temperature until the solvent content rate in the green sheet reaches 100 to 50% is 40 ° C. or more, so that a large amount of binder is used. This is to produce the portion having.

[0010]

The function of the above technical means is as follows. The present invention facilitates the production of a laminate having good adhesion between green sheets by using a green sheet having an uneven distribution layer containing a large amount of a binder near the surface, and by peeling it, peeling between layers and blistering A dense sintered body without cracks can be obtained.

Further, it becomes possible to improve the adhesiveness at a low pressure. Further, since a large amount of the binder exists only on the front surface or the back surface of the green sheet, there is no deterioration of the binder removal property. Further, the filling rate of the ceramic particles in the portion where the binder is large does not change from other portions, and since the porosity of the green sheet is smaller than other portions, defects such as deformation during sintering do not occur. By using such a green sheet, it is possible to manufacture a dense multi-layer wiring board without causing defects.

The inventors have studied the interface when laminating and bonding the green sheets. The contents will be described with reference to FIGS. 1 and 3. FIG. 1 is a schematic view showing a general laminated state of a green sheet, in which (a) is a schematic diagram before pressure bonding, (b) is a schematic diagram after pressure bonding, and FIG. 2 is a schematic diagram showing a binder state in a cross section of a green sheet. In the figure, (a) is a conventional green sheet, (b) is a schematic view of the green sheet of the present invention, and FIG. 3 is a cross-sectional view of the green sheet for examining the distribution state of the binder contained in the green sheet.
It is a perspective view showing the state where it was divided.

1 and 2, 1 is a green sheet,
2 is ceramic particles, 3 is a binder, 4 is voids, 5 is
The surface that was in contact with the blade when forming the sheet in the doctor blade method, that is, the front surface, 6 was the surface that was in contact with the polyester film when forming the sheet, that is, the back surface, 7
Is an uneven distribution layer containing a large amount of the binder 3.

As shown in FIG. 1 comparing the cross section of the green sheet 1 before and after pressure bonding, the binder 3 is softened to fill the adhesive interface, and the ceramic particles 2 at the adhesive interface are entangled with the binder 3 in a packed state. At that time, it was found that the lamination adhesion was good. When a green sheet is formed by the doctor blade method, its surface has irregularities to the extent that it corresponds to the particle size distribution of the ceramic particles used. Therefore, in order to achieve good lamination adhesion, it is necessary to supply a sufficient binder for adhesion to the lamination interface or to apply a pressure necessary for the particles to be entangled with each other.

Therefore, in the case of the present invention shown in FIG. 2 (b), as compared with the conventional green sheet 1'as shown in FIG. 2 (a), the uneven distribution layer containing much binder 3 near the surface of the green sheet. By using the green sheet 1 having No. 7, when the binder 3 is softened by heating at the time of stacking and bonding, the flow of the ceramic particles 2 is improved and the binder 3 sufficient for bonding is supplied to the stacking interface. .
The uneven distribution layer 7 has a small porosity, and the green sheet density is such that shrinkage deformation due to sintering does not occur.

The green sheet 1 as described above is produced by controlling the drying temperature. Drying of the green sheet by the doctor blade method can be generally divided into three stages. That is, gradually increasing the temperature to introduce the solvent to a temperature at which it is likely to evaporate, the middle stage where the solvent is most likely to evaporate, and the latter stage where a high temperature is applied to dry all the solvents. is there. The conventional drying by the doctor blade method is a slow drying in the initial stage, and the solvent is mainly dried in the middle stage. With such a drying method, the binder was not unevenly distributed near the surface.

On the other hand, by applying a high temperature until the solvent content becomes 50%, a binder uneven distribution layer can be formed on the surface. In order to check whether or not the binder is unevenly distributed, the distribution of the binder amount in the cross-sectional direction of the green sheet is divided into 5 in the thickness direction from the surface as shown in FIG. 3, and the 1/5 area, 2/5 area, 3/5
Areas, 4/5 areas, and 5/5 areas were subjected to quantitative analysis of the amount of binder in each area.

[0018]

Embodiments of the present invention will be described below with reference to FIGS.
In addition to this, description will be made with reference to FIGS. 4 and 8. Figure 4
FIG. 5 is a diagram showing a comparison of binder distributions when the drying temperature is changed, and FIG. 5 is an explanatory diagram showing a comparison of the drying temperature, the amount of binder, and the presence or absence of internal defects in the sintered body in each example. The multilayer wiring board is obtained by stacking and sintering green sheets having conductor wiring. First, ceramic particles,
Additives such as a binder, a solvent and a dispersant are mixed by a ball mill to obtain a uniform slurry, which is then formed into a sheet on a polyester film by a doctor blade method to obtain a green sheet.

Alumina, zirconia, mullite, magnesia, calcia, borosilicate glass, etc. are used as the ceramic particles in the present invention, and polyvinyl alcohol, polyvinyl butyral, polyethylene glycol, acrylic resin, etc. are used as the binder. As the solvent, lower alcohols such as methanol, ethanol, butanol, isobutanol, and isopropanol, acetone, water, trichloroethylene, tetrachloroethylene and the like are used.

A through-hole is processed, holes are filled with a conductor, wiring is printed on the green sheet, several tens of green sheets having these conductor wirings are stacked, and a pressure is applied while heating to form a laminate. Then, by sintering this laminated body, a multilayer wiring board is obtained. In each of the examples of the present invention, a green sheet having an uneven distribution layer containing a large amount of a binder near the surface of the green sheet is used, and the green sheet contains a solvent in the green sheet in a drying step produced by a doctor blade method. The drying temperature is 40 until the rate reaches 100 to 50%.
A green sheet having an uneven distribution layer containing a large amount of a binder near the surface is prepared at a temperature of not less than ° C.

Example 1 As 100 parts of mullite as ceramic particles, 35 parts of silica, 3 parts of alumina,
2 parts magnesia, modified acrylic resin 12 as binder
0.5 part of a carboxylic acid-based dispersant and 38 parts of water as a solvent were added, and a slurry was prepared by mixing with a ball mill. After adjusting the viscosity, a green sheet having a thickness of 200 μm was prepared by a doctor blade method.

The drying temperature at this time was 70.degree. The green sheet is divided into 5 in the thickness direction as shown in FIG. 3, and from the top, for convenience, 8 is a 1/5 area, 9 is a 2/5 area, 10 is a 3/5 area, and 11 is a 4/5 area. , 12 were named 5/5 area. The cut section was polished and the binder content was determined. Figure 4 shows the binder distribution at that time.
It was shown to. In FIG. 4, the horizontal axis represents the green sheet position and the vertical axis represents the binder amount (%). The experimental results are shown in Fig. 4.
As shown by the mark, the binder amount is 40% in the 1/5 area,
The binder amount in the 2/5 area to 5/4 area was 20% or less.

This green sheet was cut into 100 mm square pieces, punched and printed with wiring, and then 40 layers were laminated to form 1
It was pressure-bonded at 20 ° C. and 50 kg / cm ² . Further, this laminated body was sintered at 1600 ° C. to manufacture a multilayer wiring board. A test piece having a width of 1 cm was prepared from this multilayer wiring board and polished, and then a cross-section was observed to examine the presence or absence of defects.
As a result, as shown in FIG. 5, defects such as peeling, swelling and cracks were not recognized between the layers of the sintered body.

Example 2 The composition of the ceramic particles, binder, solvent, dispersant, etc. of the green sheet is the same as in the previous example. The drying temperature in the green sheet forming process by the doctor blade method was set to 50 ° C. The result of examining the distribution of the binder by the same means as in the above example is
As shown by ▲ in FIG. 4, the binder amount is 3 in the 1/5 area.
5%, the amount of binder is 2 in the 2/5 area to 5/5 area
It was 0% or less. With this green sheet,
A multilayer wiring board was prepared in the same manner as in the previous example in the sintering process, and the cross section was similarly observed. As a result, as shown in FIG. 5, no internal defect of the sintered body was recognized.

[Embodiment 3] The composition of the ceramic particles, binder, solvent, dispersant, etc. of the green sheet is the same as in the previous embodiment. The drying temperature in the green sheet forming process by the doctor blade method was set to 40 ° C. The result of examining the distribution of the binder by the same means as in the above example is
As shown by □ in Fig. 4, the binder amount is 3 in the 1/5 area.
1%, 2/5 area to 5/5 area has 2 binder amount
It was near 0% or 20% or less. Using this green sheet, a multilayer wiring board was prepared in the same manner as in the previous example in the stacking and sintering steps, and the cross section was similarly observed. As a result, as shown in FIG. 5, no internal defect of the sintered body was recognized.

[Embodiment 4] The composition of the ceramic particles, binder, solvent, dispersant, etc. of the green sheet is the same as in the previous embodiment. The drying temperature in the green sheet forming process by the doctor blade method was set to 30 ° C. The result of examining the distribution of the binder by the same means as in the above example is
As shown by ● in Fig. 4, the binder amount is 2 in the 1/5 area.
3%, binder amount is 2/5 area-5 / 5 area
It was near 0% or 20% or less. Using this green sheet, a multilayer wiring board was prepared in the same manner as in the previous example in the stacking and sintering steps, and the cross section was similarly observed. As a result, as shown in FIG. 5, internal defects of the sintered body were recognized.

Comparative Example 1 A comparative example shows data of a multilayer wiring board manufactured by a conventional technique for reference. The drying temperature in the green sheet forming process by the doctor blade method was 25 ° C. As a result of investigating the distribution of the binder by the same means as in the previous embodiment, as shown by Δ in FIG. 4, there is no uneven distribution layer containing much binder,
In the 5th to 5 / 5th areas, the binder amount was around 20%. Using this green sheet, the stacking and sintering steps were also performed by the conventional technique, a multilayer wiring board was produced, and the cross-section was similarly observed. As a result, as shown in FIG. 5, internal defects of the sintered body were recognized.

In each of the above-mentioned embodiments, the composition of the ceramic particles, the binder, the solvent, the dispersant, etc. of the green sheet is constant, and the drying temperature is changed. In addition to the above, the present inventors have also conducted experiments in which the binder addition amount is changed to, for example, 10 to 16 parts, although detailed implementation data is not shown here. Hereinafter, some consideration will be given, including the above-mentioned examples and the experimental results in which the binder addition amount is changed.

FIG. 6 is a diagram showing the relationship between the amount of binder (%) present in the surface layer of the green sheet and the amount of defects (%) in the sintered body. The results shown in FIG. 5 and Examples 1 to 1 above.
The result of measuring the amount of defects in the sintered body by changing the added amount of the binder used in 4 to 10 to 16 parts is as shown in FIG. 6, and the surface layer of the green sheet is irrespective of the added amount of the binder. Proved to depend on the amount of binder present,
It was confirmed that the binder amount was 24% or more.

FIG. 7 shows the green sheet density (g / c
m ³⁾ and is a diagram showing a relationship between the particle packing rate (%).
The composition used in Examples 1 to 4 and the binder addition amount were set to 1
FIG. 7 shows the relationship between the green sheet density and the particle packing rate in the state before sintering with the composition changed from 0 part to 16 parts.

The lamination adhesiveness is greatly influenced by the state of the binder, but when the green sheets are laminated, the green sheets are deformed, that is, the entanglement of particles at the adhesion interface described above. If it does not occur, adhesion is difficult. The condition under which this entanglement is possible is a green sheet density of 2.2 g / cm ³ or less in FIG. 7, that is, a particle packing rate of 70% or less. Also, due to the characteristics of the sintered body, the lower limit of the green sheet density is 1.3 g /
cm ³ , and the particle packing rate is 40%.

Therefore, the particle packing rate of the green sheet per unit volume is 40% to 70%, and the particle packing rate of the portion where the binder is unevenly distributed is also 40% to 70%. In the same way in the thickness direction, the porosity per unit volume of the unevenly distributed portion of the binder is smaller than the porosity of the other portion, thereby producing a laminate having excellent lamination adhesion between the green sheets. And by sintering this, a dense and highly reliable multilayer wiring board free from defects such as peeling between layers, blistering, and cracks can be obtained.

Next, FIG. 8 is a diagram showing the relationship between the temporal transition in the drying of the green sheet and the residual solvent amount (%) in the sheet. Here, the conditions are not particularly described, but the measurement results under the conditions 1, 2, and 3 are plotted by ●, ■, and Δ. The solvent is rapidly dried in the middle of the drying period, and the residual amount of the solvent is around 50%. When the residual amount of the solvent is 50% or less, it becomes difficult to form the uneven distribution layer in the green sheet. Therefore, it is necessary to set the drying temperature to 40 ° C. at which the uneven distribution layer can be formed before the residual amount of the solvent reaches 50%. is there. From the results shown in FIGS. 4 and 5 above, no internal defect of the sintered body was observed under the condition that the drying temperature was 40 ° C. or higher.

Therefore, in the drying process by the doctor blade method, the solvent content in the green sheet is 100 to 100%.
Since the drying temperature up to 50% is 40 ° C. or higher, a portion having a large amount of binder can be produced,
This facilitates the production of a laminate having excellent lamination adhesion between green sheets, and by sintering this,
It is possible to obtain a dense and highly reliable multilayer wiring board that does not cause defects such as peeling between layers, blistering, and cracks.

[0035]

As described in detail above, according to the present invention, by using a green sheet having an uneven distribution layer containing a large amount of binder, it is easy to produce a laminate having excellent lamination adhesion between the green sheets. By sintering this, it is possible to provide a method for producing a dense and highly reliable multilayer wiring board in which defects such as peeling between layers, blistering, and cracks do not occur.

[Brief description of drawings]

FIG. 1 is a schematic view showing a laminated and pressure-bonded state of a general green sheet.

FIG. 2 is a schematic diagram showing a state of a binder in a cross section of a green sheet.

FIG. 3 is a perspective view showing a state in which the green sheet is divided into five in the cross-sectional direction in order to check the distribution state of the binder contained in the green sheet.

FIG. 4 is a diagram showing a comparison of binder distributions when the drying temperature is changed.

FIG. 5 is an explanatory diagram showing a comparison of the drying temperature, the amount of binder, and the presence or absence of internal defects in the sintered body in each example.

FIG. 6 is a diagram showing the relationship between the amount of binder present in the surface layer of the green sheet and the amount of defects in the sintered body.

FIG. 7 is a diagram showing the relationship between green sheet density and particle packing rate.

FIG. 8 is a diagram showing a relationship between a temporal transition in the drying of the green sheet and the amount of residual solvent in the sheet.

[Explanation of symbols]

 1 Green Sheet 2 Ceramic Particles 3 Binder 4 Voids 5 Front Surface 6 Back Surface 7 Uneven Distribution Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Sawako Takahata, Sawako Takahata, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Inside the Hitachi, Ltd. Institute of Industrial Science (72) Naoko Hosaki 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd., Production Engineering Laboratory (72) Inventor, Mitsuhiro Takasaki, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture

Claims (5)

[Claims] 1. A method for manufacturing a multilayer wiring board, comprising laminating and sintering green sheets having conductor wiring, wherein a green sheet having an uneven distribution layer containing a large amount of a binder is used near a surface of the green sheet. Method for manufacturing multilayer wiring board. 2. The binder amount of the uneven distribution layer is 24% or more of the added binder amount that is present in the surface layer when the green sheet is divided into five equal parts in the thickness direction. Manufacturing method of multilayer wiring board. 3. The vicinity of the surface of the green sheet is defined as being from the surface of the ceramic particles existing on the outermost surface of the green sheet to a thickness corresponding to ⅕ of the green sheet in the thickness direction. A method for manufacturing the multilayer wiring board described. 4. The particle packing rate of the green sheet per unit volume is 40% to 70%, and the particle packing rate of a portion where the binder is unevenly distributed is also 40% to 70%, and the particle packing rate is the green sheet. The method for manufacturing a multilayer wiring board according to claim 1, wherein the porosity per unit volume of the portion where the binder is unevenly distributed is smaller than the porosity of other portions while being equal in the thickness direction. 5. The green sheet is manufactured by a doctor blade method, and in the drying step, the drying temperature is 40 ° C. or higher until the solvent content in the green sheet reaches 100 to 50%. The method for manufacturing a multilayer wiring board according to claim 1, wherein a portion having a large amount of binder is produced.