JP2002246752A - Via hole structure of ceramic multilayer board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide via hole structure in a ceramic multilayer board that prevents defects, such as cracks from being easily generated on a ceramic green sheet, arranged near the outside at burning, and at the same time, has superior reliability in connection. SOLUTION: A through-hole, having a specific diameter, is formed on each of the ceramic green sheets 2 and 3 and is filled with conductive paste 13, thus forming via holes 14a, 14b, and 16 for lands, and relaying via holes 15a to 15d, 17a, and 17b. The diameter of the via holes 14a, 14b, and 16 is set larger than that of the relaying via holes 15a to 15d, 17a, and 17b. The plural sheets 2 and 3 are laminated for burning in one piece. Each of the via holes 14a, 14b, and 16 for lands, and the relaying via holes 15a to 15d, 17d, and 17b is connected for composing via holes 18 and 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a via hole structure in a ceramic multilayer substrate.

[0002]

2. Description of the Related Art Conventionally, a via hole shown in FIG. 7 has been known as a via hole in a ceramic multilayer substrate. This via hole 55 is formed as follows. A through hole having the same diameter is formed in each of the plurality of ceramic green sheets 52. Next, each of the through holes is filled with a conductive paste 58 to form a relay via hole 55a.
After that, the ceramic green sheets 52 are stacked and pressed to form a laminate. Via hole 55 for relay
a to 55f are connected in the stacking direction of the sheets 52 to form the via holes 55. Thereafter, the laminate is fired to obtain the ceramic multilayer substrate 51. Then, for example, a capacitor electrode 60 and the like are formed on the surface of the ceramic multilayer substrate 51 by a method such as screen printing so as to cover the exposed end surface of the via hole 55.

[0003]

However, when the sheets 52 are stacked, the conventional via hole 55 has a problem in that, as shown in FIG. The position of the relay via hole 55f (diameter 0.2 mm) exposed on the surface of the ceramic multilayer substrate 51 and the position of the relay via hole 55e (diameter 0.2 mm) adjacent to the relay via hole 55f are, for example, 1 There is a case where a part of the edge of the relay via hole 55e protrudes from the outer periphery of the relay via hole 55f by a shift of about ４ (about 50 μm).

When the laminate is fired in such a state, the ceramic green sheets 52 and the relay via holes 55a are formed.
Due to the difference in firing shrinkage behavior of the intermediate via holes 55f to 55f, a strong stress acts on the edge of the relay via hole 55e protruding from the outer periphery of the relay via hole 55f, and the outermost ceramic green sheet 52 has a defect such as a crack C. May occur.

The positional deviation between the relay via holes also occurs between the relay via holes 55b to 55e which are not exposed on the surface of the ceramic multilayer substrate 51. However, defects such as cracks due to misalignment are unlikely to occur in the ceramic green sheet 52 disposed inside the laminate, and the ceramic green sheet 52 disposed near the outside of the laminate such as the relay via hole 55e. 5
In No. 2, defects such as cracks due to displacement are likely to occur.

The via hole 55 and the capacitor electrode 6
There is also a problem that the connection area with 0 is small and the connection reliability is relatively low.

Accordingly, an object of the present invention is to provide a via hole structure of a ceramic multi-layer substrate having high connection reliability, in which defects such as cracks are less likely to occur in ceramic green sheets disposed near the outside during firing. It is in.

[0008]

In order to achieve the above object, the via hole structure of the ceramic multilayer substrate according to the present invention comprises: (a) a land via hole formed by filling a through hole with a conductive material; A first ceramic sheet;
(B) at least a second ceramic sheet provided with a relay via hole having a smaller diameter than the land via hole, formed by filling the through hole with a conductive material,
(C) a via hole formed by stacking the first ceramic sheet and the second ceramic sheet such that the first ceramic sheet provided with the land via hole is on the outside, and the land via hole and the relay via hole are connected to each other; Is formed, and the land via hole is exposed on the surface of the ceramic multilayer substrate.

With the above configuration, the diameter of the land via hole is larger than the diameter of the relay via hole. Therefore, even if the position of the land via hole is shifted from the position of the relay via hole adjacent to the land via hole, the relay via hole is not removed. The edge of the via hole is hard to protrude from the outer periphery of the land via hole. Further, the connection area between the via hole and an electrode or the like provided on the ceramic multilayer substrate becomes larger than before, and the connection reliability is improved.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a via hole structure of a ceramic multilayer substrate according to the present invention, together with a method of manufacturing the same, will be described below with reference to the accompanying drawings.

As shown in FIG. 1, a plurality of ceramic green sheets 2 and 3 are prepared by kneading a magnetic ceramic powder, a dielectric ceramic powder, or a glass ceramic powder together with a binder and the like. In each of the ceramic green sheets 2, relay through-holes 5a to 5d, 7a, and 7b having the same diameter are formed at predetermined positions. Similarly, through holes 4a, 4b, 6 for lands are formed at predetermined positions in each of the ceramic green sheets 3.

The diameter of the land through holes 4a, 4b, 6 is set to be larger than the diameter of the relay through holes 5a to 5d, 7a, 7b. Preferably, the diameter of the land through-holes 4a, 4b, 6 is equal to the diameter of the relay through-holes 5a to 5d, 7a, 7b.
Set to 5 to 3.0 times. In the present embodiment, the land through holes 4a, 4b, 6 are circular through holes having a circular cross section and a diameter of 0.3 mm, and the relay through holes 5a to 5d, 7
a and 7b are circular in cross section and 0.2 mm in diameter.
Through hole. These through holes 4a to 7b are formed by a punch die, a laser, or the like.

Next, as shown in FIG.
b, Ag, Cu, Ag-Pd, Ni,
A conductive paste 13 such as Au is filled by a printing method or the like. As a result, the land via holes 14a, 14b,
16 and relay via holes 15a to 15d, 17a, 1
7b is formed. Further, although not shown, a wiring pattern is formed on each sheet 2 by printing a pattern of a conductive paste.

As shown in FIG. 3, a plurality of sheets 2 and 3 obtained in this manner are connected to land via holes 14a and 14a.
The sheets 3 provided with b and 16 are stacked so as to be on the outside, that is, the uppermost layer and the lowermost layer. next,
This laminate is pressed by a hot press method. Land and relay via holes 14a, 14b, 15a to 15d
Form via holes (through holes) 18 in the direction in which the sheets 2 and 3 are stacked. Also, the land and relay via holes 16, 17a, 17b are
3 are connected in the stacking direction to form a via hole 19. The laminated body after the pressure bonding is integrally fired to form the ceramic multilayer substrate 1.

The ceramic multilayer substrate 1 having the above configuration
Have via holes 18 and 19 built-in. Here, the via hole 18 has the axes of the land via holes 14a and 14b and the axes of the relay via holes 15a to 15d arranged on the same straight line. The via hole 19 is arranged such that the axis of the land via hole 16 and the axis of the relay via holes 17a and 17b are slightly shifted (eccentric).
The land via holes 14a and 14b arranged at both ends of the via hole 18 and the land via hole 16 arranged at one end of the via hole 19 are exposed on the upper and lower surfaces of the ceramic multilayer substrate 1.

Then, as shown in FIG. 4, the diameter of the land via holes 14a, 14b, 16 is
5a to 15d, 17a, and 17b, which are larger than the diameters of the land via holes 14a, 14b, and 16, and the relay via hole 1
Even if the positions of 5a, 15d, and 17a deviate, the edges of relay via holes 15a, 15d, and 17a are unlikely to protrude from the outer periphery of land via holes 14a, 14b, and 16. Therefore, when firing the laminate, the ceramic green sheets 2 and 3 and the land and relay via holes 14a to 14
The stress generated due to the difference in firing shrinkage behavior of b does not concentrate on the edges of the relay via holes 15a, 15d, 17a, and defects such as cracks are less likely to occur in the ceramic green sheet 3 disposed outside. In addition, when the thickness of the ceramic green sheet is smaller, defects such as cracks due to misalignment are more likely to occur.

Further, as shown in FIG. 5, when the surface mount type electronic component 31 is mounted on the upper surface of the ceramic multilayer substrate 1, the land via holes 14a, 16 and the electronic component 3
Since the first external terminal electrodes 32 and 33 are electrically connected with a large connection area, the electronic component 31 and the via hole 1 are electrically connected to each other.
8, 19 connection reliability can be improved. Similarly, as shown in FIG. 6, when the capacitor electrode 60 (the opposite capacitor electrode is not shown) is formed on the upper surface of the ceramic multilayer substrate 1, the connection reliability can be improved.

Moreover, the land via holes 14a, 14
Since b and 16 are buried in the substrate 1 (having substantially the same thickness as the ceramic green sheet 3), compared with the case where land electrodes are separately formed on a multilayer substrate,
The total thickness dimension can be reduced, and the ceramic multilayer substrate 1 suitable for reducing the height of the electronic device can be obtained.

The via hole structure of the ceramic multilayer substrate according to the present invention is not limited to the above embodiment, but can be variously changed within the scope of the invention.
For example, in the above-described embodiment, a via hole functioning as a signal line has been described, but the present invention can be applied to a via hole functioning as an inductor. This inductor (via inductor) has the same structure as the via hole 18 or 19 shown in FIG. 3, and has an axis in a direction parallel to the stacking direction of the ceramic green sheets 2 and 3. When a current flows through the inductor (via inductor), a magnetic field circling around a plane perpendicular to the axial direction of the inductor (in other words, a plane parallel to the surfaces of the ceramic green sheets 2 and 3) around the inductor. appear.

Further, as the via hole for relay or the via hole for land, one having a rectangular cross section may be used (example size of relay via hole: 0.3 × 0.4 mm,
Land via hole size example: 0.4 × 0.5m
m).

[0021]

As is apparent from the above description, according to the present invention, since the diameter of the land via hole is made larger than the diameter of the relay via hole, the position of the land via hole and the position adjacent to the land via hole are increased. Even if the position of the relay via hole is shifted, the edge of the relay via hole does not easily protrude from the outer periphery of the land via hole. Therefore, when the laminated body is fired, the stress generated due to the difference in firing shrinkage behavior between the ceramic green sheet and the via hole does not concentrate on the edge of the relay via hole, and cracks and the like are formed on the ceramic green sheet disposed near the outside. Defects are unlikely to occur. Further, the connection area between the via holes and the electrodes and the like provided on the ceramic multilayer substrate can be made larger than before, and the connection reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a manufacturing procedure of one embodiment of a via hole structure of a ceramic multilayer substrate according to the present invention.

FIG. 2 is a sectional view showing a manufacturing procedure following FIG. 1;

FIG. 3 is a sectional view showing a manufacturing procedure following FIG. 2;

FIG. 4 is a plan view of the via hole shown in FIG. 3;

FIG. 5 is a partial cross-sectional view showing a state in which the surface-mount type electronic component is mounted on the ceramic multilayer substrate shown in FIG. 3;

FIG. 6 is a sectional view showing a state in which capacitor electrodes are formed on the ceramic multilayer substrate shown in FIG. 3;

FIG. 7 is a cross-sectional view showing a via hole structure of a conventional ceramic multilayer substrate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ceramic multilayer board 2 ... Ceramic green sheet (2nd ceramic sheet) 3 ... Ceramic green sheet (1st ceramic sheet) 4a, 4b, 6 ... Land through-holes 5a-5d, 7a, 7b ... Relay through-hole 13 ... conductive pastes 14a, 14b, 16 ... land via holes 15a-15d, 17a, 17b ... relay via holes 18, 19 ... via holes

Claims (1)

[Claims] A first ceramic sheet having a land via hole formed by filling a through hole with a conductive material; and a first ceramic sheet having a smaller diameter than the land via hole formed by filling a through hole with a conductive material. At least a second ceramic sheet provided with a relay via hole, wherein the first ceramic sheet and the second ceramic sheet are stacked so that the first ceramic sheet provided with the land via hole is outside, and A ceramic multilayer substrate having a built-in via hole formed by connecting a via hole and the relay via hole is formed, and the land via hole is exposed on the surface of the ceramic multilayer substrate. Via hole structure.