JP2003347684A - Ceramic substrate and manufacturing method therefor - Google Patents

Abstract

(57) Abstract: When a conductor is divided into a through-hole having a C-face portion overlapping with a dividing groove after forming a conductor, there is no generation of divided burrs and no separation of the conductor in the through-hole portion. The swell that occurs sometimes is kept low. Kind Code: A1 A ceramic substrate 1 molded and fired with a die having a punch 5 having a blade 5c for forming a dividing groove on a C surface portion 5b and a mold 6 for forming a dividing groove, wherein the C of the through hole 2 is formed.
The dividing groove 3 is formed up to the surface portion 2a, and the depth D1 of the dividing groove 3 is formed to be the same as or deeper than the depth D2 of the C surface portion 2a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic substrate for an electronic component, in which a conductor is formed in a through hole and then divided between the through holes.

[0002]

2. Description of the Related Art FIG. 8 (a) is a plan view of a general ceramic substrate 11 for an electronic component in which a plurality of divided grooves 13 are formed so as to overlap a through hole 12. FIG. The main use of the through hole 12 of the ceramic substrate 11 of this shape is an end face electrode. After forming a conductor for conducting the front and back of the ceramic substrate 11 in the through hole 12 of the sheet-like ceramic substrate 11, the dividing groove is formed. By dividing 13 and 14, FIG.
A ceramic substrate 11a having a plurality of semicircular concave portions 15 as shown in the perspective view of (b) is obtained.

The semicircular recess 15 has an end face electrode 16 for electrically connecting the front and back of the ceramic substrate 11a.
Although not shown, the ceramic substrate 11a is mounted on a circuit board (not shown).
This is for electrically connecting the electronic component circuit chip or the resistive film mounted on the surface a to the circuit board land by the end face electrode 16.

A through hole 12 for forming these conductors
As shown in FIG. 8C, a C-plane portion 17 is often formed on the surface side of the through-hole 12 so that the paste serving as a conductor is smoothly sucked, as shown in the sectional view of the ceramic substrate 11 shown in FIG. ing.

As a method of manufacturing a ceramic substrate 11 having a shape in which the dividing groove 13 overlaps the through hole 12 having the C-plane portion 17 by a mold, as shown in a sectional view of FIG.
A punch 18 having a C-surface portion 18b and blades 19 for forming a dividing groove on the left and right sides of the punch 18 are mounted on a mold and pressed against a ceramic green sheet, as shown in a plan view of the ceramic substrate 11 in FIG. 9B. The through-hole 12 and the dividing groove 13 are formed, and the ceramic substrate 11 is obtained by firing at a predetermined temperature.

However, as shown in the cross-sectional view of the ceramic substrate 11 shown in FIG. 9C, the dividing groove 13 and the through hole 12 have a shape in which the dividing groove 13 is interrupted in the vicinity of the through hole 12. As a result, There is a problem that when dividing the dividing groove 13, dividing burrs occur.

According to Japanese Patent Application Laid-Open No. 4-206802,
The through holes 112 and the dividing grooves 113 shown in the plan view of the ceramic substrate 111 in FIG. 10A are intended to solve the problem of the dividing burrs and to prevent the flowing into the dividing grooves 113 when the paste is sucked into the through holes 112. And FIG.
As shown in the cross-sectional view of FIG.
A large-diameter hole 112a is provided on the front surface side and a small-diameter hole 112b is provided on the rear surface side.
13 is formed on the side of the above-described large-diameter hole 112a and is formed to be shallower than the large-diameter hole 112a.

As for the manufacturing method, as shown in FIG. 10C, a dividing groove 113 is formed by a blade (forming blade) 119 and a through-hole 11 is formed by a punch (through-hole punching pin) 118.
2 is pressed against the ceramic green sheet at the same time, and is molded. Then, in the next step, the outer periphery is cut with a dividing groove orthogonal to the dividing groove 113.
The molding of the projection 12a is shown in FIG.
19a, but the detailed structure is not described.

[0009]

When the through hole 12 overlapping the dividing groove 13 is formed by the punch 18 and the blade 19 having the C-surface portion 18b shown in FIG. 9A, as shown in FIG. 9C. In addition, the dividing groove 13 is interrupted at the C-plane portion 17 of the through hole 12, and when the dividing groove 13 is divided, divided burrs are generated. And in extreme cases, partial conductor peeling occurs.

According to the above-mentioned Japanese Patent Application Laid-Open No. 4-206802, the depth of the dividing groove 113 is set to be smaller than the depth of the hole 112a having a large diameter of the through hole 112 shown in FIG. However, when a rectangular recess is formed by pressing against a ceramic green sheet, a bulge occurs due to relief of stress on the surface of the ceramic substrate, which has a problem that circuit printing formed later is adversely affected. Further, if the depth of the large-diameter hole 112a is set to be small in order to suppress the bulging around the hole, the depth of the dividing groove 113 is further reduced, and even if the problem of the paste flowing into the dividing groove is solved, In this case, as in the case described above, the splitting surface becomes protruding or dented, and in extreme cases, conductor peeling occurs partially. there were.

Further, when the conductor is formed because the hole 112a having a large diameter has a rectangular shape in the cross section of the through hole 112, a place where the thickness of the conductor film on the edge portions of the through holes 112 and 112a is extremely thin occurs. There has also been a problem of reliability such as conductor breakage.

[0012]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a ceramic substrate having a plurality of divided grooves and a plurality of through holes formed on the surface so as to overlap the divided grooves. A side opening having a C surface portion, wherein the dividing groove is formed continuously to the C surface portion of the through hole, and the depth of the dividing groove is the same as the depth of the C surface portion of the through hole;
Alternatively, when the thickness of the ceramic substrate is t, the depth of the dividing groove is D1, and the depth of the C surface of the through hole is D2, the relational expression is 0.08 ≦ D1 / t ≦ 0.40 0.08 ≦ D2 / t ≦ 0.20 D1 ≧ D2.

Further, in the method of manufacturing a ceramic substrate having a plurality of divided grooves formed on a surface thereof and a through-hole having a plurality of C-plane portions so as to overlap the divided grooves, the punch for piercing the through-holes may have It has a straight portion and a C surface portion having a diameter larger than the straight portion diameter in the middle thereof, and comprises a pair of left and right blades pertaining to the C surface portion or the straight portion,
A step of mounting a blade for forming a dividing groove so as to have a depth equivalent to the blade of the punch between the plurality of blades of the punch, forming a mold, and punching a ceramic green sheet with the mold. And firing the punched ceramic green sheet at a predetermined temperature.

[0014]

Embodiments of the present invention will be described below.

FIG. 1A is a plan view showing an example of the ceramic substrate of the present invention.

The ceramic substrate 1 has a plurality of divided grooves 3 and 4 on its surface and a plurality of through holes 2 overlapping the divided grooves 3. The through hole 2 has a C-side portion 2a at the front side opening portion.
As shown in FIG. 1B, a sectional view obtained by dividing the dividing groove 2 is provided such that the dividing groove 3 is a C-plane portion 2 a of the through hole 2.
And the depth D1 of the dividing groove 3 is equal to or greater than the depth D2 of the C surface portion 2a of the through hole 2.

Next, a method for manufacturing the ceramic substrate 1 of the present invention will be described.

FIG. 2A is a perspective view of a punch 5 for piercing the through hole 2 which is an example of the present invention. The punch 5 for piercing has a straight portion 5a at the tip and a straight portion 5 It has a C-face portion 5b having a diameter larger than the diameter of 5a, and is provided with a pair of left and right blades 5c that are applied to the C-face portion 5b or the straight portion 5a.

Next, as shown in the sectional view of FIG. 2B, a dividing groove is formed between the blades 5c of the plurality of punches 5 so as to have the same depth as the blades 5c of the punch 5. A blade is attached to form a mold, and a ceramic green sheet is punched with the mold to obtain a raw product.

Next, the obtained green product, which is a punched ceramic green sheet, is fired at a predetermined temperature to form a through hole 2 having a C surface 2a shown in FIG. The ceramic substrate 1 in which the dividing grooves 3 are continuously formed up to 2a is obtained.

The material of the ceramic substrate 1 of the present invention is not particularly limited, and a ceramic sintered body containing alumina, zirconia, mullite, silicon nitride, aluminum nitride or the like as a main component can be used. Also, although the dividing groove 3 overlapping with the through hole 2 of the ceramic substrate 1 of the present invention has been described in only one direction, the dividing groove 3 in any direction is formed on the dividing groove 3, 4. May be.
Further, the sectional shape of the divided groove is substantially V-shaped including V-shape, U-shape, and multi-stage V-shape. However, the present invention is not limited to this, and any shape having a substantially C-plane shape including a curved surface shape may be used.

Further, the ceramic substrate 1 of the present invention is prepared by adding a binder, a sintering aid and the like to a ceramic powder mainly composed of the above-mentioned material by a known doctor blade method or roll compaction method. A punch 5 and a blade 6 for forming a dividing groove are provided in a mold on a ceramic green sheet formed into a shape, and are simultaneously molded by pressing the punch 5 and the blade 6 on the ceramic green sheet. The material is preferably a cemented carbide in terms of strength.

Furthermore, the ceramic substrate 1 of the present invention can be manufactured by firing the ceramic green sheet, which is a raw product obtained as described above, at a predetermined temperature.

The ceramic substrate 1 of the present invention thus obtained is, for example, a single ceramic substrate 1 shown in FIG.
As shown in the perspective view of a, the through hole 2 of the above-mentioned sheet-shaped ceramic substrate 1 becomes a semicircular recess 8 in the single ceramic substrate 1a after division, and this semicircular recess 8 is used as an end face electrode 7. Often. In the manufacturing process, the paste is smoothly sucked because the C-plane portion 2a is formed in the through-hole 2, and the conductor is cut off at the edge portion because the surface of the through-hole 2 is not extremely rectangular. A uniform film thickness can be formed over each part of the through-hole 2 without generation of the like. Furthermore, since the dividing groove 3 reaches the C-plane portion 2a, the dividing property is good, and a burr-like protrusion or a dent is formed at the position of the end surface electrode 7 of the ceramic substrate 1a divided into a single body. The problem of partial peeling from ceramics does not occur.

In order to provide these effects, FIG.
Is preferably 8 to 20% of the thickness t of the ceramic substrate 1 with respect to the thickness t of the ceramic substrate 1, and the depth D1 of the dividing groove 3 is equal to or greater than the depth D2 of the C surface portion 2a. The preferred range is 8 to 40% of the thickness t of the ceramic substrate 1. Also, C of the through hole 2
The width W of the surface portion 2a is for smoothing the suction of the paste for forming the conductor, and may be determined from the pattern design such as the clearance between the adjacent electrodes, at least about 5 to 20% of the thickness t of the ceramic substrate 1. It is good if it is in the range of. Note that the depth D1 of the division groove 3 refers to the division groove 3 between the through holes 2 and the C surface portion 2a of the through hole 2 shown in FIG.
The division grooves 3a in the area are collectively referred to, and the depth D1 of each of the division grooves 3 and 3a is formed at the same depth in order to obtain good division performance.

Here, the depth D1 of the dividing groove 3 between the through holes 2
The depth of the C-plane portion 2a of the through-hole 2 is equal to or greater than the depth D2, because the C-plane portion 2a of the through-hole 2 is pressed into a ceramic green sheet by a die. When the depth D2 of the surface portion 2a is deeply formed, a bulge is formed on the peripheral surface of the through hole 2 due to its compressive stress, which hinders later circuit printing.
In order to suppress this swelling at least within about 0.8% of the thickness t of the ceramic substrate 1,
It has been found that the depth D2 of a is experimentally limited to a maximum of 20% of the thickness t.

The depth D1 of the dividing groove 3 is empirically set within the range of 8 to 40% with respect to the thickness t of the ceramic substrate 1 from the viewpoints of both dividability and crack prevention before the dividing step. It is understood that the density of the portion of the C surface portion 2a of the through hole 2 is increased by pressing, and if the depth D1 of the dividing groove 3a is smaller than the depth D2 of the C surface portion 2a, C
There is a possibility that a division failure may occur in the division groove 3a of the surface portion 2a, and in order to obtain a good division property, the division may be performed at a depth of D1 ≧ D2.

[0028]

EXAMPLE Here, a ceramic substrate 1 according to an embodiment of the present invention shown in FIG. 5A, a ceramic substrate 21 of Comparative Example 1 shown in FIG. 6A, and a comparative example 2 shown in FIG. 20 sheets of each of the ceramic substrates 31 were manufactured.
Note that the manufacturing method of Comparative Example 1 is the same as that shown in FIG.
A method in which a punch 18 having a surface 18b and a blade 19 are mounted on a mold and pressed against a ceramic green sheet, and Comparative Example 2 is a blade (forming blade) 119 and a punch (through-hole punching pin) shown in FIG. 118 was mounted on a mold and pressed against a ceramic green sheet to form it.

The ceramic green sheet used was a sheet-like sheet made of 96% alumina and formed by a doctor blade method, and had a thickness t after firing of 0.635 mm.

Ceramic substrates 1 and 2 after firing
The mold was set so that each of the dimensions 1 and 31 had the values shown in Table 1, and the ceramic green sheet was molded. Thereafter, the ceramic green sheet was fired at a maximum temperature of about 1600 ° C. in a continuous firing furnace in an oxidizing atmosphere. Then, each of the ceramic substrates 1, 21, 31 was obtained.

The through-holes 2, 22, 32 of the ceramic substrates 1, 21, 31 are formed by the single ceramic substrate 1a,
4 are formed on each of the left and right sides of the long side of 21a and 31a.
6 (b), FIG. 6 (b), and FIG. 7 (b), the large hole diameter φ1 on the front side is 0.6 mm, and the small hole diameter φ2 on the back side is 0.4 mm. 1
The width W of the C surface portions 2a and 22a and the large hole 3 of the comparative example 2
The width W of the rectangular step portion 2a is 0.1 mm (15.7% of the thickness t of the substrate), and the width W of the present invention is as shown in FIGS. 5 (c), 6 (c) and 7 (c). C surface portion 22a of Comparative Example 1
The depth D2 of the large hole 32a of Comparative Example 2 is 0.1 mm (15.7% of the thickness t of the substrate), and the depth D2 of the divided groove 3.23.33 overlapping with the through holes 2, 22, 32 is 0.1 mm. Depth D
1 is 0.1 mm (15.7% of substrate thickness t)
And

Table 1 shows the above dimensional values of the embodiment of the present invention and Comparative Examples 1 and 2.

[0033]

[Table 1]

With respect to the ceramic substrates 1, 21 and 31 of the above-described embodiment of the present invention and Comparative Examples 1 and 2,
Vertical dividing grooves 4, 24, 24,
34 is divided first, and then the divided grooves 3, 23, 33 overlapping the through holes 2, 22, 32 are divided by hand break. A single ceramic substrate 1a, 21a, 31a was prepared.

Next, FIGS. 6 (b), 7 (b) and 8 (b)
As shown in the ceramic substrates 1a, 21a, and 31a after the division, the height h1 of the burrs or the size c of the concavities opposite thereto are each measured with a metallographic microscope.
Any of the above was determined to be defective, and the number of defectives was divided by 160, which is the number of single ceramic substrates as product parts, to calculate a divided defective rate.

Further, the ceramic substrates 1a, 21
6 (c), 7 (c), 8
With respect to the height h2 of the bulge around the hole periphery shown in (c), five samples were measured with a metallographic microscope, and the average value was calculated. In addition, for the determination of the quality of the height h2 of the swelling, a criterion for rejecting 5 μm or more, which is a severe level of thick film conductor printing, was applied.

Table 2 shows the above results.

[0038]

[Table 2]

As can be seen from the results, in the embodiment of the present invention, since the division groove 3 was formed up to the C-plane portion 2a of the through hole 2, no division failure occurred. On the other hand, in the comparative example 1, since the division groove 23 is not formed at the position of the C surface portion 22a of the through hole 22, the division failure is 3.75.
%. In Comparative Example 2, the dividing property was prioritized over the bulge around the hole, and the depth D2 of the dividing groove 33 was the same as that of the embodiment of the present invention.
25% occurred. Although the cause is speculation, the through hole 32
The large hole 32a is a rectangular step, and it is considered that the stress in the dividing direction in the dividing groove 33 is dispersed at the rectangular step of the large hole 32 of the through hole 32.

Next, as for the height h2 of the swelling of the periphery of the through holes 2, 22, 32, the average value is 2.7 μm in the embodiment of the present invention and 2.5 μm in the comparative example 1 for the pass / fail judgment value of 5 μm.
μm is satisfactory. However, in Comparative Example 2, the average value of the height h2 of the bulge at the periphery of the hole was 5.7 μm, which was largely out of the standard. This is due to the fact that the molding volume of the large rectangular hole 32a is larger than that of the C-plane formation, so that the periphery of the hole is raised.

[0041]

As described above, in the ceramic substrate obtained by the manufacturing method of the present invention, the dividing groove is formed continuously up to the C-plane portion of the through hole, and the depth of the dividing groove is equal to that of the through hole. Since it is formed to be the same as or deeper than the depth of the C-plane portion, the dividing property between the through-holes is good, and the swelling on the periphery of the through-hole can be suppressed low.

Therefore, when the conductor for the end face electrode is formed and divided in the through hole overlapping the dividing groove by using the ceramic substrate of the present invention, the stress applied to the conductor at the time of division can be suppressed, and occurrence of defects such as conductor peeling can be prevented. .

[Brief description of the drawings]

FIG. 1A is a plan view showing an example of a ceramic substrate of the present invention, and FIG. 1B is a sectional view thereof.

2A is a perspective view of a punch for use in the method of manufacturing a ceramic substrate according to the present invention, FIG. 2B is a cross-sectional view of a mold using the punch for punching, and FIG. FIG. 4 is a partially enlarged plan view of the ceramic substrate of FIG.

FIG. 3 is a perspective view showing an example of a ceramic substrate of the present invention after division.

FIG. 4 is a partial sectional view of a dividing groove and a through hole in the ceramic substrate of the present invention.

5A is a plan view of a ceramic substrate of the present invention, FIG. 5B is a plan view of the divided ceramic substrate,
(C) is a sectional view of the through hole.

FIG. 6A is a plan view of a conventional ceramic substrate,
(B) is a plan view of the divided ceramic substrate, and (c) is a cross-sectional view of the through hole.

FIG. 7A is a plan view of another conventional ceramic substrate, FIG. 7B is a plan view of the divided ceramic substrate,
(C) is a sectional view of the through hole.

FIG. 8A is a plan view of a conventional ceramic substrate,
(B) is a perspective view of the divided ceramic substrate, and (c) is a cross-sectional view of the through hole.

9A is a cross-sectional view of a conventional ceramic substrate manufacturing apparatus, FIG. 9B is a partial plan view of a ceramic substrate formed thereby, and FIG. 9C is a cross-sectional view thereof.

10A is a partial plan view of another conventional ceramic substrate, FIG. 10B is a cross-sectional view thereof, and FIG. 10C is a cross-sectional view of the manufacturing apparatus.

[Explanation of symbols]

1: Ceramic substrate 1a: Single ceramic substrate 2: Through hole 2a: C surface 3: Dividing groove 3a: C surface division groove 4: Dividing groove 5: punch 5a: straight section 5b: C surface part 5c: Blade 6: Blade 7: End face electrode 8: Semicircular recess t: thickness D1: Depth D2: Depth W: width h1: height of burr h2: Height of climax c: The size of the dent

Claims (3)

[Claims] 1. A ceramic substrate having a plurality of divided grooves formed on a surface thereof and a plurality of through-holes formed so as to overlap the divided grooves, the through-holes have a C-plane portion on a front surface side opening, and the divided grooves are provided. Are continuously formed up to the C-plane portion of the through-hole, and the depth of the division groove is the same as the depth of the C-plane portion of the through-hole.
Or a ceramic substrate characterized by being deeper than this. 2. When the thickness of the ceramic substrate is t, the depth of the dividing groove is D1, and the depth of the C surface of the through hole is D2, the relational expression is as follows: 0.08 ≦ D1 / t ≦ 0.40 2. The ceramic substrate according to claim 1, wherein 0.08 ≦ D2 / t ≦ 0.20 D1 ≧ D2. 3. A method of manufacturing a ceramic substrate having a surface formed with a plurality of divided grooves and a through hole having a plurality of C-surface portions so as to overlap the divided grooves. It has a straight portion and a C surface portion having a diameter larger than the straight portion diameter in the middle thereof, and comprises a pair of left and right blades pertaining to the C surface portion or the straight portion,
A step of mounting a blade for forming a dividing groove so as to have a depth equivalent to the blade of the punch between a plurality of blades of the punch and forming a mold, and punching a ceramic green sheet with the mold. And firing the punched ceramic green sheet at a predetermined temperature.