JP4677382B2 - Manufacturing method of ceramic substrate - Google Patents

Description

The present invention relates to a method for producing a ceramic substrate which is a multi-piece ceramic aggregate substrate of the multilayer structure.

  In the multilayer ceramic substrate, wiring conductors and ground conductors are formed not only on the main surface on which chip components etc. are mounted, but also between internal layers. Electrically connected. Further, when this type of ceramic substrate is used in an electronic circuit module incorporated in a high-frequency circuit, a shield case made of sheet metal is often attached to the ceramic substrate to electromagnetically shield chip components on the main surface. . In that case, a mounting structure is generally used in which a plurality of leg pieces provided at the corners of the shield case are inserted into each through hole penetrating the ceramic substrate and soldered together, and the shield case is formed on the main surface. Since the mounting area of the chip component is covered, the through hole into which the leg piece is inserted is usually disposed on the outer peripheral portion of the ceramic substrate.

  When manufacturing a ceramic substrate having such a multilayer structure, first, a plurality of ceramic green sheets are laminated and pressure-bonded to form a multilayer, and then the dividing grooves are engraved on the main surface in a lattice shape. Next, the multilayered green sheet is fired to form a ceramic aggregate substrate (large format substrate), and the aggregate substrate is divided along a dividing groove to be separated into a large number of ceramic substrates ( For example, see Patent Document 1).

When the singulated ceramic substrate has a through hole, conventionally, the through hole has been formed by the following procedure. That is, a pilot hole is formed in a through-hole formation portion and a conductive paste (electrode paste) is filled in the ceramic green sheet to be each layer of the ceramic aggregate substrate. Next, after a plurality of green sheets are laminated and pressure-bonded to form a multilayer, a through hole having a smaller diameter than the pilot hole is formed in the conductive paste filling portion with respect to the multilayer green sheet. Thereafter, when the multilayer green sheet is fired, a cylindrical through-hole conductor (electrode part) surrounding the through hole is obtained.
Japanese Patent Laying-Open No. 2001-251024 (second page, FIG. 10)

  By the way, when the miniaturization of the multilayer structure ceramic substrate described above is promoted, it becomes difficult to secure a mounting area of the chip component covered by the shield case on the main surface. There is an increasing demand to attach the shield case in such an arrangement that the mounting area can be expanded to the outermost peripheral portion of the main surface. Specifically, by mounting the leg pieces of the shield case in the through holes at the corners of the ceramic substrate, it is possible to secure a mounting area having a size substantially equal to that of the main surface. However, since the electrode material such as silver serving as a through-hole conductor has the property of diffusing into the surrounding green sheet and locally lowering the mechanical strength of the ceramic aggregate substrate, the grid-like divided grooves of the ceramic aggregate substrate If through holes are provided in the vicinity of the crossing point (the part that becomes the corner of the ceramic substrate after the division), the division failure that the ceramic aggregate substrate is not correctly divided along the dividing groove near the through hole in the division process. It tends to happen. That is, since the outer peripheral surface of each ceramic substrate corresponding to the divided end surface of the ceramic aggregate substrate is likely to be irregular in the vicinity of the through hole, it is difficult to avoid the deterioration of the manufacturing yield.

  If a through hole is formed across the dividing grooves of the ceramic aggregate substrate, a non-cylindrical through hole conductor (electrode) is obtained by dividing the through hole into two or four equal parts on the outer peripheral surface of the separated ceramic substrate. However, if the cylindrical electrode is divided in the dividing step, a lot of burrs are generated on the fracture surface, and it is not preferable to adopt such a method.

The present invention has been made in view of the drawbacks inherent in the related art, the purpose of that is, pieces made dividing the ceramic aggregate substrate into a desired shape provided with a through-hole conductor to the intersection near the dividing groove It is an object of the present invention to provide a method for manufacturing a ceramic substrate that facilitates miniaturization of the substrate.

To achieve the above object, the method for producing a ceramic substrate according to the present invention, a multilayer compression bonding process to obtain a multi-layer green sheet by crimping by stacking a plurality of ceramic green sheets, multilayer on the multilayer green sheet A through-hole forming step of forming a through-hole penetrating the green sheet and a cylindrical electrode surrounding the through-hole, and a plurality of dividing grooves on the main surface of the multilayer green sheet along two directions perpendicular to each other A step of forming a dividing groove formed in a shape, and a crossing portion removal by punching in the thickness direction of the multilayer green sheet over a predetermined region including a part of the cylindrical electrode located in the vicinity of the crossing portion of the dividing grooves And firing the multilayer green sheet to form a ceramic aggregate substrate after completion of the process and the dividing groove forming process and the crossing part removing process. And a dividing step of dividing the ceramic aggregate substrate along the dividing grooves into pieces into a plurality of ceramic substrates after the firing step, and at the corner portion of the ceramic substrate in the crossing portion removing step. The formed notch and the semi-annular through-hole conductor in plan view that protrudes from the notch at the remaining part of the cylindrical electrode exist.

  In this way, in the state of the unfired multilayer green sheet, the crossing portion of the lattice-shaped dividing groove is punched over a predetermined area, and a semicircular through-hole conductor (electrode portion) in plan view is exposed to the punched portion. If this is done, even if the through-hole conductor is in the vicinity of the crossing portion of the dividing groove, the portion where there is a possibility of division failure can be removed by the punched portion. It becomes possible to divide correctly along. In other words, the ceramic aggregate substrate can be singulated into a ceramic substrate of a desired shape by punching out in advance the parts that are likely to be broken due to a decrease in mechanical strength due to diffusion of the electrode material of the through-hole conductor. Thus, since the punched portion exists as a notch in the corner of the ceramic substrate, the manufacturing yield does not deteriorate even if the through-hole conductor is positioned in the corner of the ceramic substrate.

  In the manufacturing method of the present invention, a cross-sectional portion of a grid-like divided groove is punched over a predetermined region in a state of an unfired multilayer green sheet, and a semi-circular through-hole conductor in plan view is exposed to the punched portion. Even if the through-hole conductor is in the vicinity of the crossing portion of the dividing groove, the portion where there is a possibility of division failure can be removed by the punched portion. Can be correctly divided along the dividing groove. In other words, the ceramic aggregate substrate can be singulated into a ceramic substrate of a desired shape by punching out in advance the parts that are likely to be broken due to a decrease in mechanical strength due to diffusion of the electrode material of the through-hole conductor. Thus, since the punched portion exists as a notch in the corner of the ceramic substrate, the manufacturing yield does not deteriorate even if the through-hole conductor is positioned in the corner of the ceramic substrate.

  FIG. 1 is a plan view of an electronic circuit module according to an embodiment of the present invention, and FIG. 2 is an explanatory view showing a manufacturing process of a ceramic substrate of the electronic circuit module. FIG. 3 is a plan view showing the ceramic aggregate substrate before being singulated into the ceramic substrate, FIG. 4 is an enlarged view of a portion A in FIG. 3, FIG. 5 is a perspective view of the main part showing the corner of the ceramic substrate, and FIG. FIG. 7 is an explanatory view showing a mounting structure of a leg piece of a shield case with respect to a corner portion of the ceramic substrate, and FIG.

  The electronic circuit module shown in FIG. 1 includes a multilayer ceramic substrate 1, a chip component (not shown) mounted on the main surface 1a of the ceramic substrate 1, and a sheet metal attached to the ceramic substrate 1 so as to cover the main surface 1a. It is mainly composed of a shield case 2 made of metal. The ceramic substrate 1 is formed with a wiring conductor, a ground conductor, etc. (not shown) between the main surface 1a and the inner layers, and the main surface 1a is electrically connected to the layers and between different layers by a via hole conductor (not shown). Yes. The ceramic substrate 1 is obtained by dividing a ceramic aggregate substrate (LTCC substrate) 14 described later into individual pieces. The ceramic substrate 1 is formed in a substantially square shape in plan view, but notches 3 are provided at two corners at the diagonal positions among the four corners. That is, both end portions of one diagonal line of the main surface 1a are removed in the plate thickness direction to form the notches 3. As shown in FIG. 5, the notch 3 communicates with a through-hole 5 surrounded by a through-hole conductor (electrode part) 4 having a C-shape in plan view (semi-annular in plan view). 4 projects in the notch 3.

  The shield case 2 is provided with leg pieces 21 at two diagonal positions among the four corners. As shown in FIG. 7, the leg piece 21 is joined to the through-hole conductor 4 by solder 6 in the through hole 5 of the ceramic substrate 1. Thereby, since the shield case 2 is attached to the ceramic substrate 1 in a state where most of the main surface 1a is covered, the chip components and the like on the main surface 1a can be electromagnetically shielded. Note that the leg pieces 21 may be provided at all four corners of the shield case 2, and in that case, the notches 3 and the through-hole conductors 4 may be disposed at the four corners of the ceramic substrate 1.

  The manufacturing method of the ceramic substrate 1 will be described with reference to FIGS. 2 and 3. First, as shown in FIG. 2A, a ceramic green sheet 7 containing a low-temperature sintered ceramic material is prepared. Then, holes having predetermined sizes are formed in the through hole forming portions and via hole forming portions of the green sheet 7, respectively. At this time, as shown in FIG. 2 (b), the through hole forming portions of the green sheet 7 are formed. Is formed with a pilot hole 8 having a diameter larger than that of the through hole 5. Next, a conductive paste that becomes a wiring conductor, a ground conductor, and a via-hole conductor (not shown) is printed on the green sheet 7, and a conductive paste 9 that becomes a through-hole conductor 4 as shown in FIG. 2C. Is printed to fill the pilot hole 8.

  Next, as shown in FIG. 2 (d), a multilayer green sheet 10 is formed by laminating a plurality of ceramic green sheets 7 and press-bonding them. Alignment is made so that the via hole formation location matches. Next, as shown in FIG. 2 (e), the through hole 5 is formed in the through hole forming portion of the multilayer green sheet 10 to form an unfired cylindrical electrode 9a. That is, the cylindrical electrode 9 a surrounding the through hole 5 is obtained by drilling the through hole 5 having a diameter smaller than that of the lower hole 8 at the center of the conductive paste 9 filled in the lower hole 8.

  Thereafter, in order to make the cylindrical electrode 9 a a non-cylindrical through-hole conductor 4, a number of punched holes 11 are formed in a predetermined region of the multilayer green sheet 10. These punched holes 11 are formed by punching out regions corresponding to the intersections of the divided grooves 12 and 13 (see FIG. 3) formed in the main surface 10a of the multilayer green sheet 10 in the next divided groove forming step. is there. That is, after forming these punched holes 11, the V-shaped divided grooves 12 and 13 are formed in a lattice shape along two directions orthogonal to each other on the main surface 10 a of the multilayer green sheet 10, thereby 10a is divided into a large number of small sections corresponding to the respective ceramic substrates 1, but since the punched holes 11 are formed in advance at the intersections of the dividing grooves 12 and 13, the shape of each small section has two corners. It becomes a nearly square shape with a notch. Further, the unfired cylindrical electrode 9a is punched by about 1/4 in the circumferential direction by the punched hole 11, and becomes a non-fired through-hole conductor 4 having a C-shape in plan view. Are opposed to each other through a common punched hole 11 (see FIG. 4). In the present embodiment, the divided groove forming step is performed after the punched hole 11 is formed. However, the punched hole 11 may be formed after the divided groove forming step.

  Next, as shown in FIG. 3, the multilayer green sheet 10 is fired at a low temperature to form a ceramic aggregate substrate (LTCC substrate) 14. Then, after mounting chip parts (not shown) on each small section of the main surface 14 a of the ceramic aggregate substrate 14, the leg pieces 21 inserted into the through holes 5 are soldered to the through-hole conductors 4 to each small section. Install the shield case 2. Thereafter, the ceramic aggregate substrate 14 is divided along the dividing grooves 12 and 13 and separated into a large number of ceramic substrates 1, whereby a large number of electronic circuit modules as shown in FIG.

  As described above, in the method for manufacturing the ceramic substrate 1 according to the present embodiment, the intersection of the lattice-shaped dividing grooves 12 and 13 in the state of the unfired multilayer green sheet 10 is a predetermined region including a part of the cylindrical electrode 9a. The through-hole conductor 4 (remaining part of the cylindrical electrode 9a) having a C-shape in plan view (semi-annular in plan view) is exposed to the punched hole 11. Therefore, even if the through-hole conductor 4 to which the leg piece 21 of the shield case 2 is solder-bonded is positioned at the corner portion of the ceramic substrate 1 in order to promote downsizing, a portion where there is a risk of division failure is formed by the punch hole 11. Since it can be removed in advance, the fired ceramic aggregate substrate 14 can be correctly divided along the dividing grooves 12 and 13, and the manufacturing yield is not deteriorated. In other words, if the portion of the through-hole conductor 14 that is likely to be divided due to a decrease in mechanical strength due to the diffusion of the electrode material is removed in advance by the punched holes 11, the ceramic aggregate substrate 14 is formed into a ceramic substrate having a desired shape. 1, and the punched hole 11 exists as a notch 3 in the corner of the ceramic substrate 1.

  Moreover, since the leg piece 21 of the shield case 2 is attached to the corner of the ceramic substrate 1, the electronic circuit module according to this embodiment can cover almost the entire area on the main surface 1a with the shield case 2. This is suitable for downsizing. In addition, since the through-hole conductor 4 having a C-shape in plan view (semi-annular shape in plan view) is projected from the notch 3 provided at the corner of the ceramic substrate 1, the ceramic substrate 1 has a structure as described above. There is no possibility of causing a division failure in the manufacturing process, and therefore it can be manufactured with a good yield.

  It should be noted that the shape of the punched holes 11 formed in the intersections of the divided grooves 12 and 13 of the multilayer green sheet 10 is not limited to the above-described embodiment, and for example, hexagonal punched holes 11 as shown in FIG. Or the elliptical hole 11 as shown in FIG. 9 may be sufficient.

It is a top view of the electronic circuit module which concerns on the example embodiment of this invention. It is explanatory drawing which shows the manufacturing process of the ceramic substrate of this electronic circuit module. It is a top view which shows the ceramic assembly board | substrate before dividing | segmenting into this ceramic substrate. It is the A section enlarged view of FIG. It is a principal part perspective view which shows the corner part of this ceramic substrate. It is explanatory drawing which shows the attachment structure of the leg piece of the shield case with respect to the corner | angular part of this ceramic substrate. It is principal part sectional drawing which shows the solder joint state of this leg piece. It is a principal part enlarged view which shows the modification of a punch hole. It is a principal part enlarged view which shows the modification of a punch hole.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic substrate 1a, 10a, 14a Main surface 2 Shield case 3 Notch 4 Through-hole conductor (electrode part)
DESCRIPTION OF SYMBOLS 5 Through-hole 7 Ceramic green sheet 9 Conductive paste 9a Cylindrical electrode 10 Multilayer green sheet 11 Punched hole 12,13 Dividing groove 14 Ceramic assembly board 21 Leg piece

Claims (1)

A lamination pressure bonding step of obtaining a multilayer green sheet by laminating and pressure bonding a plurality of ceramic green sheets; and
A through hole forming step of forming a through hole penetrating the multilayer green sheet and a cylindrical electrode surrounding the through hole in the multilayer green sheet;
A dividing groove forming step of forming a plurality of dividing grooves in a lattice shape along two directions orthogonal to each other on the main surface of the multilayer green sheet;
A crossing portion removing step of punching in the thickness direction of the multilayer green sheet over a predetermined region including a part of the cylindrical electrode located in the vicinity of the crossing portion of the divided grooves;
A firing step in which the multilayer green sheet is fired to form a ceramic aggregate substrate after the split groove forming step and the crossing portion removing step are completed;
A division step of dividing the ceramic aggregate substrate along the division grooves after the firing step into individual ceramic substrates,
At the corner of the ceramic substrate, there is a notch formed in the crossing part removing step and a semicircular through-hole conductor in plan view that protrudes from the notch at the remaining part of the cylindrical electrode. A method for manufacturing a ceramic substrate .

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