JP3229540B2 - Manufacturing method of ceramic multilayer substrate - Google Patents

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 multilayer substrate by manufacturing a ceramic multilayer substrate by a green sheet laminating method.

[0002]

2. Description of the Related Art In recent years, in order to reduce sintering shrinkage in the surface direction of a ceramic substrate and improve the dimensional accuracy of the substrate, as shown in JP-A-5-503498, a green sheet serving as an insulating layer of a ceramic substrate is used. On both upper and lower surfaces, a dummy green sheet that does not sinter at the sintering temperature of the green sheet is laminated, and after sintering the green sheet while pressing from above, the unsintered material adhered to both surfaces of the sintered body There is a method of manufacturing a ceramic substrate by removing a dummy green sheet.

[0003]

Incidentally, a ceramic substrate is often configured as a multilayer substrate by laminating a plurality of green sheets by a green sheet laminating method. Since this ceramic multilayer substrate has a conductor pattern formed in an inner layer, as shown in FIG. 4, a laminate of green sheets 11 is sandwiched between two dummy green sheets 12 and pressed, or FIG. As shown in the figure, the pressed body of the green sheet 11 is connected to two dummy green sheets 12.
When baking while pressing with the press 13 between the substrates, the substrate surface is deformed so that the portion where the conductor pattern 14 is present in the inner layer of the substrate becomes convex, and the flatness of the substrate surface is deteriorated. There is. Such a decrease in the flatness of the substrate surface causes a reduction in the reliability of a conductor pattern to be retrofitted on the substrate surface or a reduction in the bonding reliability of an IC chip mounted on the substrate surface.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for manufacturing a ceramic multilayer substrate which can improve the flatness of the substrate surface.

[0005]

According to a first aspect of the present invention, there is provided a method of manufacturing a ceramic multi-layer substrate, comprising the steps of:
On both sides of the green sheet laminate, a sheet-like constrained material having a smaller rate of change in thickness when pressed than the green sheet and not sintering at the substrate sintering temperature is pressed and pressed, and the pressed body is pressed at the substrate sintering temperature. After sintering, the sheet-like constrained substances attached to both surfaces of the sintered body are removed.

In this manufacturing method, since the rate of change in thickness of the sheet-like restraint sandwiching the green sheet laminate during compression is smaller than that of the green sheet, even if a conductor pattern is formed on the inner layer of the substrate, the surface of the substrate is The convex deformation at the conductor pattern portion is suppressed by the sheet-like restraints on both surfaces of the substrate, and the flatness of the substrate surface is ensured.

In this case, the substrate is not pressurized at the time of firing, but the flatness of the substrate surface obtained at the time of pressing is not impaired, and firing shrinkage in the direction of the substrate surface is also restrained by the sheet-like restraint. .

However, in the present invention, the firing may be performed while pressing the green sheet pressure-bonded body from above the sheet-like constrained member as in the pressure bonding. In this case, warpage and peeling (delamination) of the substrate during firing can be prevented.

Further, the laminating and pressing of the green sheets is performed by a conventional general green sheet laminating method that does not use sheet-like restraints. The green sheet is sintered at the substrate sintering temperature while being pressed against the sheet-like restraint that is smaller than the thickness change rate before the shrinkage due to the pressure sintering and does not sinter at the substrate sintering temperature. May be.

[0010] In this case, even if a convexly deformed portion is formed on the substrate surface due to the inner layer conductor pattern at the time of pressing, the convexly deformed portion of the substrate surface is pressed by sandwiching the green sheet pressurized body between the sheet-like restraints at the time of firing. The substrate surface is flattened by being pressed.

Further, the green sheet may be formed of a low-temperature fired ceramic which can be fired at 1000 ° C. or less. In this case, a relatively inexpensive alumina green sheet can be used as the sheet-like restraint.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] A ceramic multilayer substrate is formed by the following (1) to
It is manufactured through the step (7).

(1) Preparation of Green Sheet 21 First, 10 to 55% by weight of CaO, 45 to 70% by weight of SiO ₂ , 0 to 30% by weight of Al ₂ O _3, 0 to 10% by weight of impurities, and B ₂ A mixture containing 5 to 20% by weight of O ₃ is melted and vitrified at 1450 ° C., then quenched in water, and pulverized to obtain a C 3 having an average particle size of 3.0 to 3.5 μm.
making _{aO-SiO 2 -Al 2 O 3} -B 2 O 3 based glass powder. This glass powder is mixed with 50 to 65% by weight (preferably 60% by weight) and 50 to 35% by weight (preferably 40% by weight) of alumina powder containing 0 to 10% by weight of impurities to prepare a low-temperature fired ceramic powder. A solvent (eg, toluene, xylene), a binder (eg, an acrylic resin) and a plasticizer (eg, D
OP) and kneaded well to obtain a viscosity of 2000-4000.
A slurry of 0 cps is prepared, and a green sheet 11 having a thickness of, for example, 0.1 to 0.4 mm is prepared using a normal doctor blade method.

(2) Preparation of sheet-shaped constraining member 22 (alumina green sheet) Alumina powder of 100% by weight of Al ₂ O ₃ was used, and the same solvent, binder and plasticizer as described above were added to this alumina powder, and A slurry is prepared by kneading, for example, using a normal doctor blade method, for example, a thickness of 0.1 to 0.4 mm.
Is produced and used as the sheet-like restraint 22. The sheet-shaped restraint 22 has a smaller rate of change in thickness at the time of pressing, which will be described later, than that of the green sheet 21 and does not sinter unless heated to 1550 to 1600 ° C. The rate of change in the thickness of the sheet-shaped restraint 22 during compression can be adjusted by the type and properties of the binder (resin), the amount of the plasticizer mixed, the particle size (raw density) of the alumina particles, and the easiness of breaking the aggregated particles. Generally, as the mixing amount of the plasticizer increases, the green sheet 21 becomes softer, and the rate of change in thickness at the time of pressure bonding increases.

(3) Punching The green sheet 21 is cut into a predetermined size using a punching die, a punching machine, or the like, and a via hole is punched at a predetermined position of the green sheet 21. Also,
The sheet-like restraint 22 is also cut into the same size as the green sheet 21 or a size larger than that.

(4) Conductor pattern printing In the via holes of each green sheet 21, Ag, Ag / P
A conductor pattern 23 for wiring is screen-printed on the green sheet 21 which is filled with a conductor paste such as d, Au, Ag / Pt, and Cu and laminated on the inner layer using the conductor paste having the same composition as described above.

(5) Lamination / Crimping As shown in FIG. 1, a plurality of green sheets 21 are laminated so as to be sandwiched by two sheet-like restraints 22. Then, this laminated body is, for example,
Heated and pressed to be integrated under the conditions of ~250kg / cm ^2. At this time, the sheet-like constraining member 22 sandwiching the green sheet laminate has a rate of change in thickness at the time of press-bonding,
1 is smaller than that of the conductive pattern 23 on the inner layer of the substrate.
Is formed, the surface of the substrate is
The sheet-shaped restraints 22 on both sides of the substrate may be convexly deformed at the portion.
And the flatness of the substrate surface is ensured.
In FIG. 1, the number of stacked green sheets 21 is two, but it goes without saying that three or more green sheets 21 may be stacked.

(6) Sintering The pressure-bonded body manufactured as described above is subjected to a substrate sintering temperature of 800 to 10 using a normal electric continuous belt furnace.
The ceramic multilayer substrate is fired at 00 ° C. (preferably 900 ° C.). At this time, when Cu is used as the conductor pattern 23 of the inner layer, it is necessary to bake in a reducing atmosphere to prevent oxidation, but Ag, Ag / Pd, Au,
When Ag / Pt is used, firing can be performed in an oxidizing atmosphere (air).

In this case, the sheet-like restraining members 22 (alumina green sheets) laminated on both sides of the substrate are 1550 to 1
Since it does not sinter unless heated to 600 ° C.,
If it is fired at 000 ° C., the sheet-like restraint 22 is left unsintered. However, during the firing process, the sheet-like restraint 2
The solvent and binder in 2 are scattered and remain as alumina powder.

During the firing, the substrate is not pressurized, but the flatness of the substrate surface obtained at the time of pressing is not impaired, and the flatness of the substrate surface is ensured. Further, firing shrinkage in the direction of the substrate surface is also restrained by the sheet-shaped restraint 22, and the dimensional accuracy of the substrate is also ensured.

(7) Finishing After firing, the sheet-like restraint 22 (alumina powder) adhered to both sides of the substrate is removed by polishing or the like.
Ag, Ag / Pd, Au, Ag / Pt, C
A surface conductor pattern is screen-printed using a conductor paste such as u, and is fired at 1000 ° C. or less.

The present inventor conducted the following experiment in order to evaluate the effect of sandwiching the laminate of the green sheets 21 with the two sheet-like restraints 22 and pressing the laminated body. .

<< Experiment 1 >> The green sheet 21 of the test sample was made of the above-mentioned CaO—SiO ₂ —Al ₂ O ₃ —B ₂ O
₃ series glass powder 50-65% by weight and alumina powder 50-
It is formed of a low-temperature fired ceramic consisting of a mixture with 35% by weight. 30 green sheets
2 mm, and the surface was cut out as shown in FIG.
The conductor pattern 23 of mm square was printed. The printed thickness of the conductor pattern 23 is 100 μm. Then, as shown in FIG. 1, the green sheet 21 on which the conductor pattern 23 was not printed was superimposed on the green sheet 21 on which the conductor pattern 23 was printed, and the green sheet 21 was sandwiched between two sheet-like restraints 22. These were used as test samples. As the sheet-like restraining member 22, an alumina green sheet containing 100% by weight of Al ₂ O ₃ was used.

The relationship between the pressing force of the test sample at the time of pressing and the rate of change in the thickness of the green sheet 21 is shown in Table 1 below.

[0025]

[Table 1]

Here, the thickness change rate is calculated by the following equation. Thickness change rate = (Thickness dimension before pressing-Thickness dimension after pressing)
/ Thickness before pressing x 100 (%)

Table 2 below shows the measurement results of the thickness change rate of the sheet-shaped restraint member 22, the unevenness of the substrate surface before firing, and the unevenness of the substrate surface after firing when pressed at a pressure of 100 kgf / cm ^2. It is shown.

[0028]

[Table 2]

Here, when the pressing force is 100 kgf / cm ² , the thickness change rate of the green sheet 21 is 13% (see Table 1). Sample No. In Nos. 1 to 3, since the rate of change of the thickness of the sheet-like constraining member 22 is smaller than the rate of change of the thickness of the green sheet 21 (13%), no irregularities are formed on the substrate surface before and after firing, and the substrate surface becomes flat. This allows
It is possible to improve the reliability of the conductor pattern to be retrofitted on the substrate surface and the bonding reliability of the IC chip mounted on the substrate surface.

On the other hand, the sample No. In Nos. 4 to 6, the rate of change in thickness of the sheet-shaped restraint 22 is equal to or greater than the rate of change in thickness of the green sheet 21 (13%). The constrained object 22) was deformed, and irregularities of about 0.06 mm were formed on the substrate surface. Such unevenness on the surface of the substrate causes a reduction in the reliability of a conductor pattern to be attached to the surface of the substrate or a reduction in the bonding reliability of an IC chip mounted on the surface of the substrate.

Table 3 below shows the rate of change in the thickness of the sheet-shaped restraint member 22 when pressed with a pressing force of 50 kgf / cm ² .
3 shows the measurement results of the unevenness of the substrate surface before firing and the unevenness of the substrate surface after firing.

[0032]

[Table 3]

Here, when the pressing force is 50 kgf / cm ² , the rate of change in the thickness of the green sheet 21 is 10% (see Table 1). Sample No. In Nos. 7 to 9, since the rate of change in thickness of the sheet-shaped restraint 22 is smaller than the rate of change in thickness of the green sheet 21 (10%), no irregularities are formed on the substrate surface before and after firing, and the substrate surface becomes flat.

On the other hand, the sample No. In No. 10, since the rate of change in the thickness of the sheet-shaped restraint 22 is the same as the rate of change in the thickness of the green sheet 21 (10%), the surface of the substrate (sheet-like sheet) is formed such that the portion where the conductor pattern 23 is present at the time of crimping becomes convex. The constraint 22) was deformed, and irregularities of about 0.05 mm were formed on the substrate surface.

<< Experiment 2 >> The green sheet 21 of the test sample was composed of 10 to 55% by weight of MgO and 45 to 70% of SiO _2.
Mg containing 0 to 30% by weight of Al ₂ O _3, 0 to 10% by weight of impurities, and 5 to 20% by weight of B ₂ O _{3
O-SiO 2 -Al 2 O 3} -B 2 O 3 based glass powder 50
It is formed of a low-temperature fired ceramic consisting of a mixture of about 65% by weight and 50 to 35% by weight of alumina powder containing 0 to 10% by weight of impurities. Other test conditions are the same as those in Experiment 1 described above.

Table 4 below shows the relationship between the pressing force of the test sample at the time of pressing and the rate of change in the thickness of the green sheet 21.

[0037]

[Table 4]

Table 5 below shows the measurement results of the thickness change rate of the sheet-like restraint member 22, the unevenness of the substrate surface before firing, and the unevenness of the substrate surface after firing when pressed with a pressing force of 100 kgf / cm ^2. It is shown.

[0039]

[Table 5]

Here, when the pressing force is 100 kgf / cm ² , the rate of change in the thickness of the green sheet 21 is 21% (see Table 4). Sample No. In Nos. 11 to 13, the thickness change rate of the sheet-shaped restraint 22 is smaller than the thickness change rate (21%) of the green sheet 21, so that the substrate surface becomes flat before and after firing, and the substrate surface becomes flat.

On the other hand, the sample No. 14 is such that the rate of change of the thickness of the sheet-shaped restraint 22 is greater than the rate of change of the thickness of the green sheet 21 (21%). 22) is deformed, and 0.
Irregularities of about 06 mm were formed.

Table 6 below shows the rate of change in the thickness of the sheet-shaped restraint member 22 when pressed with a pressing force of 50 kgf / cm ² ,
3 shows the measurement results of the unevenness of the substrate surface before firing and the unevenness of the substrate surface after firing.

[0043]

[Table 6]

Here, when the pressing force is 50 kgf / cm ² , the thickness change rate of the green sheet 21 is 15% (see Table 4). Sample No. In Nos. 15 to 17, since the rate of change of the thickness of the sheet-shaped constraining member 22 is smaller than the rate of change of the thickness of the green sheet 21 (15%), no irregularities are formed on the substrate surface before and after firing, and the substrate surface becomes flat.

On the other hand, the sample No. Reference numeral 18 indicates that the thickness of the sheet-shaped constraining member 22 is larger than that of the green sheet 21 (15%). 22) is deformed, and 0.
Irregularities of about 05 mm were formed.

[Second Embodiment] In the first embodiment, the substrate is not pressurized during firing, but in the second embodiment, the substrate is fired while pressing the substrate also during firing. The pressure during firing is ² to ²⁰ Kgf / cm ² . The rest is the same as the first embodiment.

Also in the second embodiment, by making the rate of change of the thickness of the sheet-like restraint 22 smaller than the rate of change of the thickness of the green sheet 21, no irregularities are formed on the substrate surface, and the substrate surface becomes flat. In addition, by firing under pressure, warping and peeling (delamination) of the substrate during firing can be prevented.

[Third Embodiment] In the third embodiment, the laminating and pressing of the green sheets 21 is performed by a conventional general green sheet laminating method that does not use the sheet-like restraining members 22. As shown in FIG. 3, on both surfaces of the pressed body of the green sheet 21, sheet-like restraints smaller than the thickness change rate before the green sheet 21 starts shrinking by pressure firing and not sintered at the substrate sintering temperature. Sintering is performed at a substrate sintering temperature while pressing the substrate 22 with a pressing machine 24. The pressure during firing is ² to ²⁰ Kgf / cm ² . The rest is the same as the first embodiment.

In this case, the inner conductor pattern 23
Even if a convex deformed portion is formed on the substrate surface by firing, the pressed body of the green sheet 21 is squeezed at the time of baking.
And pressurize, the convexly deformed portion of the substrate surface is pressed down and the substrate surface is flattened.

Experiment 3 below is an experiment for evaluating the manufacturing method of the third embodiment, and the results of the experiment will be described below.

<Experiment 3> As in Experiment 1, the green sheet 21 of the test sample was CaO—SiO ₂ —Al ₂ O
₃ is obtained by forming a low-temperature fired ceramic comprising a mixture of -B ₂ O ₃ based glass powder 50-65 wt% of alumina powder 50 to 35 wt%. Sheet-shaped restraint 22
Uses an alumina green sheet of 100% by weight of Al ₂ O ₃ .

Table 7 below shows the relationship between the pressing force during firing of the test sample and the thickness change rate before the shrinkage of the green sheet 21 due to the pressure firing starts.

[0053]

[Table 7]

Table 8 below shows the measurement results of the rate of change in thickness of the sheet-shaped restraint member 22 and the unevenness of the substrate surface after firing under pressure when firing while applying a pressure of 10 kgf / cm ^2. is there.

[0055]

[Table 8]

Here, when the pressing force is 10 kgf / cm ² , the rate of change in the thickness of the green sheet 21 is 2% (see Table 7). Sample No. In 19, since the rate of change in thickness of the sheet-shaped constraining member 22 is smaller than the rate of change in thickness of the green sheet 21 (2%), the unevenness of the substrate surface formed at the time of pressing the green sheet 21 is corrected by pressure baking, Becomes flat.

On the other hand, the sample No. Reference numeral 20 denotes the thickness change rate (2%) before the thickness change rate of the sheet-like restraint 22 starts to shrink by the pressure baking of the green sheet 21.
As a result, the unevenness of the substrate surface formed at the time of pressing the green sheet 21 was not corrected, and the unevenness of about 0.04 mm was formed on the substrate surface after the pressure firing.

Table 9 below shows the results of measurement of the rate of change in thickness of the sheet-shaped restraint member 22 when sintering was performed while applying pressure at a pressure of ²⁰ kgf / cm ² , and the unevenness of the substrate surface after sintering under pressure. is there.

[0059]

[Table 9]

Here, when the pressing force is ²⁰ kgf / cm ² , the rate of change in the thickness of the green sheet 21 is 4% (see Table 7). Sample No. Since the thickness change rate of the sheet-like restraint 22 is smaller than the thickness change rate (4%) before shrinkage of the green sheet 21 due to the pressure firing, the substrate surface formed when the green sheet 21 is pressed. The unevenness is corrected by pressure baking, and the substrate surface becomes flat.

On the other hand, the sample No. Reference numeral 23 denotes a thickness change rate (4%) before the thickness change rate of the sheet-like restraint 22 starts to shrink by the pressure baking of the green sheet 21.
As a result, the unevenness of the substrate surface formed at the time of pressing the green sheet 21 was not corrected, and the unevenness of about 0.04 mm was formed on the substrate surface after the pressure firing.

In the third embodiment, an unfired green sheet is used as the sheet-shaped restraining member 22, but a fired ceramic plate may be used.

In each of the above embodiments, the green sheet 21
As a material of CaO—SiO ₂ —Al ₂ O ₃ —B ₂ O
₃ system or MgO-SiO ₂ -Al ₂ O ₃ was used -B ₂ O ₃ based mixture of the glass powder and the Al ₂ O ₃ powder, SiO ₂ in addition to this -B ₂ O ₃ based glass and Al ₂ O ₃ system,
PbO-SiO ₂ -B ₂ O ₃ based glass and Al ₂ O ₃ system,
A ceramic material that can be fired at 1000 ° C. or lower, such as cordierite-based crystallized glass, may be used.

Further, a Pb perovskite compound, SrT
iO ₃ -based compound, BaTiO ₃ -based compound, CaTiO ₃
A green sheet may be formed using a dielectric ceramic such as a system compound or the like, and the green sheet may be laminated on an inner layer of the substrate to incorporate a capacitor. Further, for example, R
A resistor formed of a uO ₂ paste may be incorporated.

In addition, the present invention is not limited to the low-temperature fired ceramic multilayer substrate, but can be applied to the production of ceramic multilayer substrates such as alumina and aluminum nitride. it can.

[0066]

As is apparent from the above description, according to the method for manufacturing a ceramic multilayer substrate of claim 1 of the present invention,
When laminating a plurality of green sheets and pressing them together, a sheet-like restraint that has a smaller rate of change in thickness when pressed than the green sheets and does not sinter at the substrate sintering temperature is applied to both surfaces of the green sheet laminate. After sintering the pressed body at the substrate sintering temperature, the sheet-like restraint attached to both sides of the sintered body was removed. The flatness can be improved, and the reliability of the conductor pattern to be retrofitted on the substrate surface and the bonding reliability of the IC chip mounted on the substrate surface can be improved.

Further, in the second aspect of the present invention, the sintering is performed while pressing the green sheet pressed body from above the sheet-shaped restraint as in the case of the squeezing. Warpage and peeling (delamination) can be prevented, and a very high quality ceramic multilayer substrate can be manufactured.

In the third aspect, the sheet-like restraint is not used at the time of pressing, but the sintering is performed while the sheet-like restraint is applied to both surfaces of the green sheet press-bonded body at the time of firing. As in the first aspect, the flatness of the substrate surface can be improved.

According to a fourth aspect of the present invention, the green sheet comprises:
Since it is formed of a low-temperature fired ceramic that can be fired at 1000 ° C. or less, a relatively inexpensive alumina green sheet can be used as the sheet-like restraint, and the demand for reduction in manufacturing cost can be satisfied.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a manufacturing process according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a green sheet sample used in the experiment.

FIG. 3 is a schematic diagram showing a state during pressure firing in a third embodiment of the present invention.

FIG. 4 is a schematic view showing a comparative example.

FIG. 5 is a schematic view showing another comparative example.

[Explanation of symbols]

21: green sheet, 22: sheet-like restraint, 23:
Conductor pattern, 24 ... Pressing machine.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C04B 35/64-35/645

Claims (4)

(57) [Claims] 1. A method of manufacturing a ceramic multilayer substrate by laminating and pressing a plurality of green sheets on which a conductor pattern is formed, and sintering at a predetermined substrate sintering temperature. At the time of pressure bonding, a sheet-like restraint that has a smaller rate of change in thickness at the time of pressure bonding than the green sheets and that does not sinter at the substrate sintering temperature is pressed on both surfaces of the green sheet laminate, A method for manufacturing a ceramic multilayer substrate, comprising: sintering at a substrate sintering temperature; and removing the sheet-like restraint adhered to both surfaces of the sintered body to manufacture a ceramic multilayer substrate. 2. The method for manufacturing a ceramic multilayer substrate according to claim 1, wherein during firing, the green sheet press-bonded body is fired while pressing the green sheet pressed body from above the sheet-shaped restraint. 3. A method of manufacturing a ceramic multilayer substrate by laminating and pressing a plurality of green sheets on which a conductor pattern is formed and sintering them at a predetermined substrate sintering temperature. After laminating and pressing, a sheet-like restraint that is smaller than the thickness change rate before the green sheet starts shrinking by pressure firing and that does not sinter at the substrate sintering temperature is applied to both surfaces of the pressed body. And sintering at the substrate sintering temperature while pressurizing, and removing the sheet-like restraint from both surfaces of the sintered body to manufacture a ceramic multilayer substrate. 4. The method according to claim 1, wherein the green sheet is formed of a low-temperature fired ceramic that can be fired at 1000 ° C. or lower.