JPH11220260A - Manufacture of low-temperature baked ceramic multilayered board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a low-temperature baked ceramic multilayered board to be less warped in baking and to lessen conductor pattern resistance. SOLUTION: Conductor patterns 13 and 14 are printed on green sheets 12 with Ag conductor paste respectively. At this point, the Ag conductor paste is composed of Ag powder 0.1 to 5 μm in average grain diameter and 5 to 15 wt.% binder resin. After the patterns 13 and 14 have been printed, the green sheets 12 are laminated and bonded into one piece as heated, for instance, at a temperature of 80 to 150 deg.C under a pressure of 5 to 300 kgf/cm<2> , then the laminate is baked at a temperature of 800 to 1,000 deg.C for 20 minutes. In this case, since the Ag conductor paste is high in binder resin content, even if the surface conductor pattern 14 is compressed in a thermocompression process, the agglomeration of Ag powder contained in the surface conductor pattern 14 is relaxed by the binder resin, and a multilayered board of this constitution is less warped in baking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature fired ceramic green sheet
The present invention relates to a method for manufacturing a low-temperature fired ceramic multilayer substrate which is simultaneously fired at a temperature of not more than ° C to manufacture a low-temperature fired ceramic multilayer substrate.

[0002]

2. Description of the Related Art A low-temperature fired ceramic substrate fired at a temperature of 1000 ° C. or lower has a lower dielectric constant compared with an alumina substrate fired at around 1600 ° C., enables a high-speed signal processing, and simultaneously fires with a ceramic. There is an advantage that a low-melting-point metal such as an Ag-based conductor having a small conduction resistance can be used as a wiring conductor to be formed, and the demand has been increasing more and more in recent years. This low-temperature fired ceramic substrate is often manufactured as a multilayer substrate by laminating a plurality of ceramic green sheets in order to increase the density and reduce the size.

In general, a low-temperature fired ceramic multilayer substrate is
Often manufactured by the green sheet lamination method. In this green sheet laminating method, a plurality of low-temperature fired ceramic green sheets on which a conductor pattern is printed with a conductor paste are laminated, heat-pressed and integrated to form a laminate.
This is to produce a low-temperature fired ceramic multilayer substrate by simultaneous firing at a temperature of not more than ° C.

[0004]

The inner conductor pattern formed on the inner layer of the low-temperature fired ceramic multilayer substrate must be printed before lamination. However, the surface conductor pattern formed on the substrate surface must be printed before lamination and after lamination. Can be printed. However, when the surface conductor pattern is printed before the lamination, the firing warpage of the substrate tends to increase. It is considered that the cause is that the surface conductor pattern is compressed by the pressing force at the time of lamination, and the conductor powder in the surface conductor pattern is pushed in and agglomerated to increase the conductor density. Therefore,
Conventionally, the surface warpage of a substrate is reduced by printing a surface conductor pattern on the surface of a laminate after lamination.

However, in this manufacturing method, it is necessary to add a printing step after the laminating step, and the number of steps is increased. In addition, the expansion and contraction of the green sheet after lamination causes printing displacement of the surface conductor pattern, which adversely affects the electrical characteristics.

Therefore, using a conductor paste obtained by adding Pd powder or other sintering inhibitor to an Ag-based conductor paste,
There is a method of printing a surface conductor pattern before lamination. With this method, it is possible to reduce firing warpage of the substrate, but electrical characteristics such as an increase in conduction resistance, deterioration of solder wetting characteristics, and a decrease in adhesive strength between the substrate surface and the surface conductor are reduced. There is a disadvantage.

Since the inner conductor pattern to be printed before lamination also causes firing warpage of the substrate, it is preferable that the inner layer conductor pattern is also made of a conductor paste having less warpage of the substrate.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and accordingly, it is an object of the present invention to provide a method of manufacturing a low-temperature fired ceramic multilayer substrate capable of simultaneously reducing firing warpage of a substrate and improving electrical characteristics. Is to do.

[0009]

According to a first aspect of the present invention, there is provided a method for manufacturing a low-temperature fired ceramic multilayer substrate, wherein a conductive paste used for printing a predetermined conductive pattern comprises a conductive powder. In which an Ag-based powder is blended and a binder resin is blended in an amount of 5 to 15% by weight
A system conductor paste is used. This Ag-based conductor paste,
Since the compounding amount of the binder resin is larger than the conventional (2% by weight), even if the conductor pattern printed before lamination is compressed by the pressing force at the time of lamination, the conductor powder in the conductor pattern may be pushed and aggregated. Mitigated by binder resin,
The firing warpage of the substrate can be reduced. However, when the blending amount of the binder resin is more than 15% by weight, the tendency that the conduction resistance value becomes large becomes remarkable.
With the following, favorable electric characteristics can be obtained.

In this case, it is preferable to use an ethyl cellulose or acrylic resin as the binder resin. Ethyl cellulose resin has high thixotropy and can be used for fine patterning. Further, even if the amount of the acrylic resin is increased, the viscosity of the conductive paste is kept low, and the filling property to the via hole is good.

The Ag-based powder to be mixed with the Ag-based conductor paste has an average particle size of 0.1 to 5 μm.
m is preferably used. If the average particle size is 5 μm or more, the printability deteriorates and it becomes difficult to form a fine pattern.

If the conductor pattern is too thick, it may cause firing warpage. Therefore, it is preferable to print the conductive pattern so that the dry film thickness at the time of printing is 5 to 30 μm. Further, in order to secure an appropriate interlayer adhesive force of the low-temperature fired ceramic green sheet laminate and to prevent a compressive deformation at the time of lamination, a pressing force at the time of lamination is 5 to 300 kg.
f / cm ² is preferable.

[0013] Both the inner conductor pattern and the surface conductor pattern may be formed using the Ag-based conductor paste described above, or only one of them may be formed (claim 5). When forming
As described in claim 6, the surface conductor pattern may be printed before lamination. This eliminates the need to add a printing step after the laminating step, and improves productivity. In addition, the problem of printing displacement of the surface conductor pattern due to expansion and contraction of the green sheet after lamination is solved, and it is easy to cope with fine patterning.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment (1)] A method for manufacturing a low-temperature fired ceramic multilayer substrate 11 according to an embodiment (1) of the present invention will be described below with reference to FIGS. First, a green sheet of a low-temperature fired ceramic is tape-formed using a slurry of the low-temperature fired ceramic. On this occasion,
As the low-temperature fired ceramic, CaO—SiO ₂ —Al
₂ O ₃ -B ₂ O ₃ based glass 50-65 wt% (preferably 60 wt%) alumina 50-35% by weight (preferably 40 wt%) using a mixture of. In addition, for example,
_{MgO-SiO 2 -Al 2 O 3} -B 2 mixture of O ₃ based glass and alumina, a mixture of SiO ₂ -B ₂ O ₃ based glass and alumina, PbO-SiO ₂ -B ₂ O ₃ based glass and alumina And a low-temperature fired ceramic material that can be fired at 800 to 1000 ° C., such as a cordierite-based crystallized glass.

Thereafter, the green sheet of the low-temperature fired ceramic formed into a tape is cut into a predetermined size, and a via hole (not shown) is punched at the predetermined position.
The green sheet 12 of each layer is formed. Thereafter, an Ag-based conductor paste is filled into the via hole of the green sheet 12 of each layer, and the inner conductor pattern 13 is screen-printed on the green sheet 12 of each layer except the uppermost layer using the Ag-based conductor paste having the same composition. At the same time, the surface conductive pattern 14 is screen-printed on the uppermost green sheet 12. At this time, the inner conductor pattern 13 and the surface conductor pattern 14 are screen-printed so that the dry film thickness is 5 to 30 μm.

The Ag-based conductor paste used in this printing step is prepared by mixing a binder resin and an organic solvent with an Ag-based powder and kneading the mixture sufficiently. In this case, in addition to Ag powder, Ag-Pd,
A powder of an alloy or a mixture of metals such as Ag-Pt, Ag-Pd-Pt, and Ag-Au may be used. However, it is preferable to use an Ag-based powder having an average particle size of 0.1 to 5 μm. If the average particle size is 5 μm or more, the printability deteriorates and it becomes difficult to form a fine pattern.

Ethyl cellulose or acrylic resin is used as a binder resin to be mixed with the Ag-based conductor paste. Ethyl cellulose resin has high thixotropy and can be used for fine patterning. Further, even if the amount of the acrylic resin is increased, the viscosity of the conductive paste is kept low, and the filling property to the via hole is good. The mixing ratio of the Ag-based powder, the binder resin, and the organic solvent in the Ag-based conductor paste is 50 to 9 for the Ag-based powder.
0% by weight, 5 to 15% by weight of a binder resin, and 5 to 35% by weight of an organic solvent.

The printing of the via conductor, the inner conductor pattern 13, and the surface conductor pattern 14 is not necessarily performed by using Ag of the same composition.
It is not necessary to use a system conductor paste, and at least one of the inner conductor pattern 13 and the surface conductor pattern 14 may be formed using the Ag conductor paste having the above composition.

After the printing step, the green sheets 1 of each layer
2 and laminating the laminate at, for example, 80 to 150 ° C. and 5 to
Under pressure of 300 kgf / cm ² , they are integrated by thermocompression bonding. If the pressure at the time of lamination is lower than 5 kgf / cm ² , the pressing force between the green sheets 12 is insufficient, delamination occurs, and 300 kgf / cm ^2.
If it is larger, the problem of compression deformation of the green sheet 12 occurs. Therefore, the pressing force at the time of lamination is 5 to 300 k
gf / cm ² is preferable.

After completion of the laminating step, the laminated body of the green sheets 12 is fired at 800 to 1000 ° C. for 20 minutes under a hold condition, and the green sheets 12 of each layer are simultaneously fired together with the inner layer / surface layer conductor patterns 13 and 14 to reduce the temperature. The fired ceramic multilayer substrate 11 is manufactured.

[Embodiment (2)] In the embodiment (1), the surface conductor pattern 14 is printed before lamination.
In the embodiment (2) shown in FIG. 1, after the green sheets 12 of each layer are laminated without printing the surface layer conductor pattern 14, the surface layer conductor pattern 14 is printed on the surface of the laminated body, and the surface layer is fired to be cooled at a low temperature. The fired ceramic multilayer substrate 11 is manufactured. Except for this, it is the same as the above-described embodiment (1).

[0022]

EXAMPLES The present inventors conducted a test to evaluate the relationship between the blending amount of the binder resin in the Ag-based conductor paste used for printing the conductor pattern, the firing warpage, and the conduction resistance, and the test results were obtained. Are shown in Table 1 below.

[0023]

[Table 1]

In this evaluation test, two production methods (1),
The firing warpage and conduction resistance of the low-temperature fired ceramic sample substrate manufactured in (2) were measured. Here, manufacturing method (1)
Is to print a surface conductor pattern before lamination using the process of FIG. 2 described in the above-described embodiment (1). On the other hand, in the manufacturing method (2), the surface conductor pattern is printed after lamination using the process of FIG. 3 described in the above-described embodiment (2).

In each of the production methods (1) and (2), two green sheets each having a thickness of 0.3 mm are laminated, the pressing force at the time of lamination is set to 50 kgf / cm ² , and the heating temperature is set to 110 ° C. for 15 seconds. Was performed twice. In each case, the surface conductor pattern to be printed was a square pattern of 10 mm in length × 10 mm in width, and was printed so that the dry film thickness was 15 to 25 μm. The firing of the sample substrate is performed at 890 ° C., 2
The test was performed under the condition of 0 minute hold. Since firing warpage occurs such that the surface conductor pattern portion rises, the measurement of the firing warpage is based on the portion of the substrate surface where the surface layer conductor pattern is not formed (the highest portion of the surface layer conductor pattern portion (central portion). Part) was measured.

In Examples 1, 2, and 3 and Comparative Examples 1 and 2, surface conductor patterns were printed using Ag pastes having different amounts of binder resin. The criteria for passing the quality inspection after firing are a firing warpage of 0.1 mm or less and a conduction resistance of 5.0 mΩ / □ or less.

Comparative Example 1 (compounding amount of binder resin: 2% by weight) corresponds to a conventional Ag paste and satisfies a passing criterion in terms of conduction resistance, but a method of printing a surface conductor pattern before lamination (1) Then, the firing warp does not satisfy the acceptance criteria. The cause is considered to be that the surface layer conductor pattern is compressed by the pressing force at the time of lamination, and the Ag powder in the surface layer conductor pattern is pushed in and agglomerated to increase the Ag conductor density. Even in this case, in the manufacturing method (2) in which the surface conductor pattern is printed after the lamination, since the Ag conductor density of the surface conductor pattern does not increase, the firing warp satisfies the acceptance criteria.

Comparative Example 2 (compounding amount of binder resin:
20% by weight), the firing warp satisfies the acceptance criterion regardless of whether the surface conductor pattern is printed before or after lamination.
This is because the amount of the binder resin is large, so even if the surface conductor pattern printed before lamination is compressed by the pressing force at the time of lamination, the Ag powder in the surface layer conductor pattern is forced into and coagulated by the binder resin. It is thought to be eased. However, in Comparative Example 2, since the amount of the binder resin was too large, the Ag conductor density of the surface conductor pattern was too low, and as a result, the conduction resistance was 6.8 m.
To Ω / □, failing to meet the acceptance criteria.

On the other hand, in Examples 1, 2, and 3, the compounding amounts of the binder resin were 5% by weight, 8% by weight, and 15% by weight, and as the compounding amount of the binder resin increased, the conduction resistance value increased. Although there is a tendency to increase little by little, even in Example 3 in which the amount of the binder resin is the largest among the examples, the conduction resistance value is 5.2 mΩ / □, which satisfies the acceptance criteria.
In addition, as for the firing warpage, there was a tendency that the firing warpage gradually decreased as the amount of the binder resin increased. This is probably because the effect of the binder resin to alleviate the aggregation of the conductor increases as the amount of the binder resin increases. Therefore, among the examples, the largest firing warpage is in the case where the surface layer conductor pattern is printed before lamination in Example 1 in which the blending amount of the binder resin is the smallest, and even in this case, the firing warpage is still large. 0.08 mm, meeting the acceptance criteria.

From the above test results, when the amount of the binder resin is 5 to 15% by weight, both of the firing warpage and the conduction resistance satisfy the acceptance criteria, and the low-temperature fired ceramic multilayer substrate of good quality is obtained. Was obtained.

In the example shown in FIG. 1, the surface conductor pattern 14 is formed only on the upper surface of the low-temperature fired ceramic multilayer substrate 11, but the surface conductor pattern is also formed on the lower surface of the low-temperature fired ceramic multilayer substrate 11. May be.

[0032]

As is apparent from the above description, according to the method for manufacturing a low-temperature fired ceramic multilayer substrate of claim 1 of the present invention, Ag containing 5 to 15% by weight of a binder resin is used.
Since the conductor pattern is printed using the system conductor paste, it is possible to satisfy the requirements of reducing the warpage of the substrate and reducing the conduction resistance value regardless of whether the conductor pattern is printed before or after laminating the green sheets. It is possible to manufacture a low-temperature fired ceramic multilayer substrate of good quality.

In the second aspect, since an ethylcellulose-based or acrylic-based resin is used as the binder resin, printability can be favorably maintained even if the blending amount of the binder resin is increased.

In the third aspect, since the average particle size of the Ag-based powder to be mixed with the Ag-based conductor paste is 0.1 to 5 μm, printing of a fine pattern is easy.

According to a fourth aspect of the present invention, the conductor pattern is printed so as to have a dry film thickness of 5 to 30 μm, and the pressing force at the time of lamination is 5 to 30 μm.
Since the pressure is set to 300 kgf / cm ² , the problems of delamination and compression deformation can be avoided.

In this case, the above-described A
The intended object of the present invention can be achieved by forming at least one of the inner conductor pattern and the surface conductor pattern using a g-based conductor paste. Since printing is performed with the system conductor paste, it is not necessary to add a printing step after the laminating step, so that the productivity can be improved and the problem of printing displacement of the surface layer conductive pattern due to expansion and contraction of the green sheet after lamination can be solved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a method for manufacturing a low-temperature fired ceramic multilayer substrate according to an embodiment (1) of the present invention.

FIG. 2 is a process chart showing a manufacturing process according to an embodiment (1) of the present invention.

FIG. 3 is a process chart showing a manufacturing process according to an embodiment (2) of the present invention.

[Explanation of symbols]

11: low-temperature fired ceramic multilayer substrate, 12: green sheet, 13: inner layer conductor pattern, 14: surface layer conductor pattern.

Claims (6)

[Claims] 1. A method of manufacturing a low-temperature fired ceramic multilayer substrate by simultaneously firing a low-temperature fired ceramic green sheet laminate on which a predetermined conductor pattern is printed with a conductive paste at 800 to 1000 ° C. together with the conductor pattern. The paste was prepared by mixing an Ag-based powder as a conductor powder and 5 to 15% by weight of a binder resin.
A method for manufacturing a low-temperature fired ceramic multilayer substrate, comprising using a g-based conductor paste. 2. The method according to claim 1, wherein the binder resin is an ethylcellulose-based resin or an acrylic-based resin. 3. The Ag-based powder has an average particle size of 0.1 to 3.
The method for producing a low-temperature fired ceramic multilayer substrate according to claim 1, wherein the thickness is 5 μm. 4. The predetermined conductor pattern is printed so as to have a dry film thickness of 5 to 30 μm, and a pressing force for producing the low-temperature fired ceramic green sheet laminate is 5 to 300 kgf / cm ² . The method for producing a low-temperature fired ceramic multilayer substrate according to any one of claims 1 to 3, wherein: 5. The conductor pattern according to claim 1, wherein the predetermined conductor pattern is at least one of an inner conductor pattern formed on an inner layer of the substrate and a surface conductor pattern formed on the surface of the substrate. 3. The method for producing a low-temperature fired ceramic multilayer substrate according to 1.). 6. The method according to claim 1, wherein when forming the surface conductor pattern on the surface of the substrate, the surface conductor pattern is printed before laminating the low-temperature fired ceramic green sheets. A method for manufacturing a low-temperature fired ceramic multilayer substrate.