JP2004304113A - Multilayer ceramic package - Google Patents

Abstract

A multilayer ceramic package is provided that uniformly suppresses shrinkage during ceramic sintering and reduces a decrease in internal circuit pattern accuracy due to unevenness in shrinkage.
A low-temperature fired green sheet layer in which an internal circuit pattern is formed in a multilayer ceramic package formed by simultaneously firing a low-temperature fired green sheet made of a low-temperature sintered ceramic material and a conductive paste film formed on the sheet. 1 and a low-shrinkage green sheet layer 2 provided on the low-temperature fired green sheet layer and made of a textile base material of ceramic long fibers as a basic material.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multilayer ceramic package manufactured by simultaneously firing a ceramic green sheet and a conductive paste film that are sintered at a low temperature, and more particularly to an improvement in a reduction in accuracy of a conductive pattern and an improvement in a package strength.
[0002]
[Prior art]
In the LTCC (Low Temperature Co-fired Ceramic) process, in which a ceramic green sheet and a conductive paste film are simultaneously fired at a low temperature to form a multilayer package, conventionally, distortion generated in an electrode conductor due to sintering shrinkage of ceramics is prevented. For this purpose, baking (pressing baking) is performed through a dummy layer (alumina or the like) that does not sinter at a low temperature and while restraining shrinkage in the in-plane direction by pressing (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-9-92983 (FIG. 1)
[0004]
[Problems to be solved by the invention]
In the conventional method for manufacturing a multilayer ceramic package having such a configuration, the dummy layer needs to be peeled off and discarded after firing, or a multilayer structure lacks a restraining force, resulting in a difference in shrinkage between layers. (Necking). Further, there is also a problem that the process is special in the pressure firing and it is difficult to apply the process to a cavity structure having a step in a package.
[0005]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and can uniformly suppress in-plane shrinkage during ceramic sintering, thereby reducing the internal circuit pattern accuracy due to shrinkage variation. It is an object of the present invention to obtain a multilayer ceramic package capable of reducing the decrease in the thickness and improving the package strength.
[0006]
[Means for Solving the Problems]
In a multilayer ceramic package according to the present invention, an internal circuit pattern is formed in a multilayer ceramic package obtained by simultaneously firing a low-temperature fired green sheet made of a low-temperature sintered ceramic material and a conductive paste film formed on this sheet. It has a low-temperature fired green sheet layer and a low-shrinkage green sheet layer provided on the low-temperature fired green sheet layer and made of a textile base material of ceramic long fibers as a basic material.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a sectional view of a multilayer ceramic package according to Embodiment 1 of the present invention. In the multilayer ceramic package 101 of the present embodiment, a low-shrink green sheet layer 2 is disposed on the uppermost and lowermost layers of the low-temperature fired green sheet layer 1.
[0008]
The low-temperature fired green sheet layer 1 is obtained by forming a conductor paste film (not shown) to be an internal circuit pattern on the low-temperature fired green sheet by a screen printing method, and laminating seven such sheets (in FIG. Is omitted).
[0009]
The above-mentioned low-temperature fired green sheet is made of alumina powder (AL-M41-01), Al ₂ O ₃ , SiO ₂ , B ₂ O ₃ , CaO, BaO, MgO, ZrO ₂ , which is atomized to an average particle size of 3 μm or less. A ceramic slurry composed of an inorganic powder such as silicate glass powder, an organic component such as a binder (PVB) and a dispersant (treolein), and a solvent (isobutyl acetate) is adjusted to a viscosity of 3000 to 5000 cps, and then a carrier is formed by a doctor blade method. It is applied on a film and then dried at 80 ° C.
[0010]
The low-shrinkage green sheet layer 2 is formed by weaving low-loss glass long fiber yarn (NE-Glass manufactured by Nitto Boss) at a weaving density of 46/46 yarns / 25 mm each in the longitudinal / horizontal direction, and then opening it to form an orthogonal plain weave cloth base. A material (textile substrate) is impregnated with a ceramic slurry and dried at 80 ° C.
[0011]
Then, the low-temperature fired green sheet laminate 1 and the low-shrinkage green sheet layer 2 are superimposed and heated and pressed at 80 ° C. and 300 kg / cm ² to obtain a molded body. The molded body is fired at 870 ° C. in an electric furnace to produce a multilayer ceramic package 101.
[0012]
By arranging the low-shrinkage green sheet layer 2 made of a textile base material on the uppermost layer and the lowermost layer as described above, the variation in the in-plane shrinkage rate of the sintered body is 0.07% (0.5 in the prior art). %), And the shrinkage in the in-plane direction was considerably uniformly suppressed.
[0013]
A bending test piece was cut out from the sintered body and subjected to a three-point bending test. As a result, a bending strength of 320 MPa was obtained. Since the bending strength of the sintered body without the low-shrinkage layer 2 is 250 Mpa, it is understood that about 30% strength improvement can be obtained. Further, by changing the weaving density of the long fibers in the plain woven cloth base material, it is possible to control the sheet layer thickness, electric characteristics, and mechanical characteristics.
[0014]
The multilayer ceramic package 101 of the present embodiment is provided on a low-temperature fired green sheet layer 1 on which an internal circuit pattern (not shown) is formed, and is provided so as to overlap the low-temperature fired green sheet layer 1. A low-shrinkage green sheet layer 2 as a material. Since the low-shrinkage green sheet layer 2 made of the textile base material is provided as described above, the shrinkage in the in-plane direction during ceramic sintering can be evenly suppressed. The decrease in accuracy can be reduced, and the low-shrinkage layer made of the textile base material acts as a reinforcing layer to improve the package strength.
[0015]
Embodiment 2 FIG.
FIG. 2 is a sectional view of a multilayer ceramic package according to Embodiment 2 of the present invention. In the multilayer ceramic package 102 of the present embodiment, the low shrinkage green sheet layer 3 is disposed on the uppermost layer, the lowermost layer, and the intermediate layer of the low-temperature fired green sheet layer 1.
[0016]
The low-temperature fired green sheet layer 1 is formed by forming a conductor paste film (not shown) to be an internal circuit pattern on the low-temperature fired green sheet by a screen printing method and laminating ten sheets (in FIG. The description is omitted).
[0017]
The low-shrink green sheet layer 3 is formed by weaving an alumina long fiber yarn (Alf made by Nichibi) at a weaving density of 26/26 yarns / 25 mm each in the vertical / horizontal direction and opening the cross-linked plain weave cloth base material (textile base material) with ceramics. After being impregnated with the rally, it is dried at 80 ° C. to produce.
[0018]
Then, the low-temperature fired green sheet layer 1 and the low-shrinkage green sheet layer 3 are heated and pressed at 80 ° C. and 300 kg / cm ² to obtain a molded body. This molded body is fired at 870 ° C. in an electric furnace to produce a multilayer ceramic package 102.
[0019]
By arranging the low-shrink green sheet layer 3 made of a textile base material on the uppermost layer, the lowermost layer and the intermediate layer in this way, the variation in the in-plane shrinkage rate of the sintered body is 0.06% (in the prior art). 0.5%), and the shrinkage in the in-plane direction was considerably evenly suppressed.
[0020]
A bending test piece was cut out from the sintered body and subjected to a three-point bending test. As a result, a bending strength of 350 MPa was obtained. Since the bending strength of the sintered body without the low shrinkage layer is 250 MPa, it can be understood that about 40% strength improvement can be obtained.
[0021]
In a package used in a microwave or millimeter-wave band, dielectric properties near the substrate surface layer are the most important for high-frequency transmission loss, and a low dielectric loss tangent material is disposed near the substrate surface layer as in the present embodiment. This has the effect of reducing the loss more efficiently. Similar effects can be obtained by using an orthogonal plain woven cloth base made of quartz fibers or a hybrid cloth base made by combining these different kinds of fibers.
[0022]
By using long fibers such as low loss glass, alumina and quartz having low dielectric loss as ceramic long fibers, loss can be reduced more efficiently in packages used in microwave and millimeter wave bands. can do.
[0023]
Embodiment 3 FIG.
FIG. 3 is a sectional view of a multilayer ceramic package according to a third embodiment of the present invention. In the multilayer ceramic package 103 of the present embodiment, a low-shrinkage green sheet layer 4 is disposed on the uppermost layer and the lowermost layer of the low-temperature fired green sheet layer 1.
[0024]
The low-temperature fired green sheet layer 1 is formed by forming a conductive paste film (not shown) to be an internal circuit pattern on the low-temperature fired green sheet by a screen printing method, and laminating seven sheets (in FIG. The description is omitted).
[0025]
The low-shrink green sheet layer 4 is formed by weaving low-loss glass long fibers (NE-Glass manufactured by Nitto Boss) so as to intersect each other at an angle of 60 °, and forming an opened triaxial woven fabric base (textile base). The ceramic slurry is impregnated and dried at 80 ° C.
[0026]
Then, the low-temperature fired green sheet laminate 1 and the low shrinkage green sheet layer 4 are heated and pressed at 80 ° C. and 300 kg / cm ² to obtain a molded body. The molded body is fired at 870 ° C. in an electric furnace to produce a multilayer ceramic package 103.
[0027]
By arranging the low-shrinkage green sheet layer 4 made of a triaxial woven fabric substrate on the uppermost layer and the lowermost layer as described above, it is possible to more isotropically reduce the shrinkage rate of the sintered body and its variation. Similar effects can be obtained by using other multiaxial woven fabric substrates or knitted fabric substrates.
[0028]
Embodiment 4 FIG.
FIG. 4 is a sectional view of a multilayer ceramic package according to Embodiment 4 of the present invention. In the multilayer ceramic package 104 of the present embodiment, although the low-temperature fired green sheet layer 1 and the low-temperature fired green sheet layer 5 are stacked, the low-shrinkage green sheet layer 4 is disposed on the uppermost layer and the lowermost layer.
[0029]
The low-temperature fired green sheet layer 1 is produced by forming a conductor paste film (not shown) to be an internal circuit pattern on the low-temperature fired green sheet by a screen printing method, and laminating a predetermined number of the sheets (in FIG. The description is omitted).
[0030]
The low-temperature fired green sheet layer 5 is formed by forming a resistor paste film made of ruthenium oxide (not shown) on the low-temperature fired green sheet by a printing method.
[0031]
The low-shrink green sheet layer 2 is formed by weaving low-loss glass long fiber yarn (NE-Glass manufactured by Nitto Boss) at a weave density of 46/46 yarns / 25 mm each in the length / width direction, and opening the crossed plain weave cloth base material (textile). The substrate is impregnated with a ceramic slurry and then dried at 80 ° C.
[0032]
Then, the low-temperature fired green sheet layer 1, green sheet layer 5, and low-shrinkage green sheet layer 2 are heated and pressed at 80 ° C. and 300 kg / cm ² to obtain a molded body. The molded body is fired at 870 ° C. in an electric furnace to produce a multilayer ceramic package 104.
[0033]
When the resistance value of the multilayer ceramic package 104 was measured, the variation of the measured value with respect to the design value was ± 9%. In the prior art, the variation in the resistance value of the built-in resistor is close to ± 20%, which is mainly caused by the size variation of the built-in resistor after sintering. It can be seen that with such a configuration, the dimensional accuracy is improved in each step, and a stable resistance value can be obtained.
[0034]
It should be noted that the built-in technology according to the present embodiment is also applicable to the manufacture of other component built-in packages such as capacitors and coils.
[0035]
【The invention's effect】
In a multilayer ceramic package according to the present invention, an internal circuit pattern is formed in a multilayer ceramic package obtained by simultaneously firing a low-temperature fired green sheet made of a low-temperature sintered ceramic material and a conductive paste film formed on this sheet. Since the low-temperature fired green sheet layer and the low-shrinkage green sheet layer which are provided so as to overlap the low-temperature fired green sheet layer and are basically made of a textile base material of ceramic long fibers are provided, the in-plane direction during ceramic sintering is provided. Of the conductor pattern can be reduced evenly due to uneven shrinkage, and the low shrinkage layer made of this textile substrate acts as a reinforcing layer to improve package strength. can do.
[Brief description of the drawings]
FIG. 1 is a sectional view of a multilayer ceramic package according to a first embodiment of the present invention.
FIG. 2 is a sectional view of a multilayer ceramic package according to a second embodiment of the present invention.
FIG. 3 is a sectional view of a multilayer ceramic package according to a third embodiment of the present invention.
FIG. 4 is a sectional view of a multilayer ceramic package according to a fourth embodiment of the present invention.
[Explanation of symbols]
1 Low-temperature fired green sheet layer (in which an internal circuit pattern is formed) 2 Low-shrinkage green sheet layer (basic material is an orthogonal plain woven cloth base material of low-loss glass long fiber yarn) 3 Low-shrinkage green sheet layer (alumina length 4) Low shrinkage green sheet layer (basic material is triaxial woven base material of low loss glass long fiber) 5) Low temperature firing green sheet layer (resistor is formed) ).

Claims (3)

In a multilayer ceramic package obtained by simultaneously firing a low-temperature fired green sheet made of a low-temperature sintered ceramic material and a conductive paste film formed on the sheet,
The low-temperature fired green sheet layer on which the internal circuit pattern is formed,
A low-shrink green sheet layer provided on the low-temperature fired green sheet layer and made of a long-fiber textile base material as a basic material. 2. The multilayer ceramic package according to claim 1, wherein the long fiber is any one of low loss glass having low dielectric loss property, alumina, and quartz. 3. The multilayer ceramic package according to claim 1, wherein the textile substrate is a triaxial woven fabric of the long fiber.

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