JP2005285865A - Multiple wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multiple wiring board, without peeling a metalized layer deposited on the inside surface of a through hole at the dividing of a ceramic master board, into respective wiring board regions. <P>SOLUTION: In the multiple wiring board, dividing grooves 9 are provided along the boundaries of square frame-shaped wiring board regions 3 in the principal surface of the ceramic master board 2, on which the wiring board regions 3 are arranged and formed longitudinally and laterally, and a plurality of through holes 4 over the entire surface of the inside surface, of each of which the metalized layer 6 is deposited, are formed to stride the dividing grooves 9. The metallized layer 6 progressively changes over the entire perimeter in thickness thereof, such that the farthest portion from the dividing groove 9 becomes thickest, and the portion in contact with the dividing groove 9 is set thinnest in a transverse plane. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  According to the present invention, a large number of wiring board regions, each of which is a small wiring board for mounting electronic components such as semiconductor elements and crystal resonators, are integrally formed in a vertical and horizontal arrangement on a large-area ceramic mother board. The present invention relates to a multi-piece wiring board.

  Conventionally, a small-sized wiring board for mounting and housing electronic components such as LSIs and crystal resonators was led out from the inside to the side of the recess, with an insulating base having a recess for storing the electronic component in the center of the upper surface. A wiring conductor and a metallized layer (side conductor) formed on the side surface of the insulating base so as to be connected to the lead-out end portion of the wiring conductor are provided. The metallized layer on the side surface is usually deposited on the side surface of the insulating base and on the inner surface of the groove formed in the vertical direction.

  This small wiring board is generally formed in the form of a multi-piece wiring board formed by arranging rectangular wiring board regions to be such wiring boards vertically and horizontally on a ceramic mother board. It is manufactured by dividing along the boundary of each wiring board region.

  As shown in FIGS. 3A and 3B, respectively, a plan view and a cross-sectional view taken along the line YY ′, the multi-cavity wiring board is composed of two layers made of a ceramic material such as an aluminum oxide sintered body. In this structure, a plurality of wiring board regions 33 in which concave portions 31 for mounting electronic components are formed are arranged vertically and horizontally at the center of the upper surface of a ceramic mother board 32 formed by laminating these insulating layers.

  A dividing groove 39 is formed along the boundary of each wiring board region 33, and a plurality of through holes 34 having a circular cross section are formed so as to straddle the dividing grooves 39. Has a metallized layer 36 applied thereto.

  The metallized layer 36 is connected to, for example, a wiring conductor 35 led out from the inner surface of the recess 31 to the through hole 34, and electrically connects the wiring conductors 35 to each other between adjacent wiring board regions 33, A function of leading the wiring conductor 35 to the lower surface side of the insulating base is provided.

  The reason why the wiring conductors 35 are electrically connected to each other between the adjacent wiring board regions 33 is that a plating layer for preventing oxidation or the like is deposited on the exposed surface of the wiring conductor 35 by electrolytic plating. Further, it is for supplying a current for plating to the wiring conductor 35 of each wiring board region 33 and supplying it.

  In general, an external connection conductor 37 is formed on the outer periphery of the lower surface of the ceramic mother substrate 32 so as to be connected to the metallized layer 36. Furthermore, a sealing metallization layer 38 for sealing the recess 31 by bonding a metal lid (not shown) is formed on the upper surface portion surrounding the recess 31 in each wiring board region 33. Has been.

  Then, by dividing the multi-cavity wiring board into regions to be the respective insulating bases 31, the metallized layer 36 on the inner surface of the through hole 34 formed on the boundary of each region is vertically divided into two, and metallized on the inner surface. A wiring board on which a side conductor made of a groove having the layer 36 is formed is manufactured.

  Such a wiring board accommodates an electronic component (not shown) in the recess 31 and electrically connects the electrode of the electronic component to the wiring conductor 35 on the bottom surface of the recess 31 via a bonding wire or a conductive adhesive. Then, after that, the lid is joined to the sealing metallization layer 38 so as to close the recess 31, and an electronic component is hermetically accommodated in the recess 31 to be an electronic device as a product. The external connection conductor 37 is mounted on the external electric circuit board by connecting to the wiring conductor of the external electric circuit board via solder, and the electrode of the electronic component to be accommodated is electrically connected to the external electric circuit. It will be.

  A multi-cavity wiring board is usually prepared by preparing a plurality of ceramic green sheets (hereinafter also simply referred to as green sheets) obtained by forming a raw material powder such as aluminum oxide into a sheet, and punching a part of the green sheet. And forming a through hole 34 that extends over the boundary of the wiring board region 33. Next, a metal powder paste such as tungsten is formed on the surface of the green sheet and the inner surface of the through hole 34. Is printed on a predetermined wiring conductor pattern, and then these green sheets are sequentially laminated and fired.

The metallized layer 36 deposited on the inner surface of the through hole 34 is formed by a well-known screen printing method using vacuum suction or the like. For example, the metal powder printed and filled in the through hole 34 is used. By sucking the paste from the lower side of the ceramic mother substrate 32 and removing a part of the metal powder paste, the remainder of the metal powder paste can be attached to the inner surface of the through hole 34. As shown in FIG. 4, the thickness of this metal powder paste (metallized layer 36) was substantially the same over the entire circumference. 4 shows the metallized layer 36 (attached to the inner surface of the groove 39 formed by dividing the through hole 34 in the wiring substrate region 33 formed by dividing the multi-cavity wiring substrate shown in FIG. The same parts as those in FIG. 3 are denoted by the same reference numerals.
JP 2000-68414 A

  However, in such a multi-piece wiring board, the size of each wiring board region 33 has become a small size of about several millimeters square in accordance with the recent demand for miniaturization of electronic devices. The width of the sealing metallization layer 38 is also very narrow, for example, 300 μm or less, and in order to ensure good bonding strength of a lid (not shown) to the sealing metallization 38, the sealing metallization 38. The width of is becoming a limit. Therefore, in order to further reduce the wiring board region 33, it is necessary to reduce the size of the plurality of through holes 34 formed at the boundary of the wiring board region 33.

  If the size of the through hole 34 is small, the area of the metallized layer 36 deposited on the inner surface of the through hole 34 is reduced. Usually, the metallized layer 36 deposited on the inner surface of the through hole 34 is formed with a thickness of about 10 to 15 μm. When the area of the metallized layer 36 is reduced, the adhesion strength (to peel off the metallized layer from the insulating substrate). Therefore, when the ceramic mother board 32 is divided into individual wiring board areas 33, each wiring board area 32 side is separated from each other at the boundary part between the adjacent wiring board areas 33. Since the stress acts in such a direction as to be pulled by the metallized layer 36, the metallized layer 36 deposited on the inner surface of the through hole 34 is peeled off. There has been a problem that defects such as an electrical short circuit between the metallized layers occur.

  The present invention has been devised in view of such conventional problems. The purpose of the present invention is to reduce the size of the wiring board, even if the through-hole to which the metallized layer is deposited becomes smaller. When dividing the substrate into each wiring board region, it is possible to effectively prevent peeling of the metallized layer deposited on the inner surface of the through hole, and the metallized layer deposited on the inner surface of the through hole. An object of the present invention is to provide a multi-piece wiring board in which disconnection due to peeling or short-circuiting between metallized layers does not occur.

  The multi-cavity wiring board of the present invention is provided with a dividing groove along the boundary of the wiring board area on the main surface of the ceramic mother board in which rectangular wiring board areas are arranged vertically and horizontally, and on the entire inner surface. A multi-cavity wiring board in which a plurality of through-holes with a metallized layer deposited thereon are formed so as to straddle the divided grooves, and the metallized layer has a portion farthest from the divided grooves in a transverse section. The thickness is gradually changed over the entire circumference so that the thickest portion contacting the dividing groove is the thinnest.

  In the multi-piece wiring board of the present invention, it is preferable that the metallized layer has a cross-sectional shape over the entire circumference that is axisymmetric with respect to an extension line of the dividing groove.

  Further, in the multi-cavity wiring board of the present invention, preferably, the ceramic mother board has a disposal margin area formed so as to surround the entire wiring board area on the outer periphery thereof, The frame-like conductor layer surrounding the entirety of the wiring board region, which is electrically connected to the wiring conductor formed on the main surface of the wiring board region through the through hole, is formed therein. It is a feature.

  According to the multi-cavity wiring board of the present invention, the metallized layer has a thickness that gradually changes over the entire circumference so that the portion farthest from the dividing groove in the cross section is the thickest and the portion that contacts the dividing groove is the thinnest. Therefore, the strength of the metallized layer as a coating can be increased by the thick portion (the portion where the thickness of the metallized layer is thick and the part far from the dividing groove), and when the ceramic mother board is divided into each wiring board region, It is possible to prevent the metallized layer from peeling off when the matching wiring board region is pulled to both sides. In addition, when the ceramic mother substrate is divided by the thin-walled portion (the portion where the metallized layer is thin and in contact with the dividing groove), the metalized layer can be divided into two vertically in a favorable manner, and cracks are formed in the metalized layer and the ceramic mother. It is possible to effectively prevent the metallized layer from peeling off by proceeding to the interface with the substrate.

  In the multi-cavity wiring board of the present invention, preferably, the metallized layer has a cross-sectional shape over the entire circumference that is axisymmetric with respect to the extension line of the dividing groove. Since the film strength of the metallized layers deposited on the inner wall can be made uniform, it is possible to prevent peeling of the metallized layer that occurs when the adjacent wiring board regions are pulled to both sides more effectively. it can.

  Further, in the multi-cavity wiring board of the present invention, preferably, the ceramic mother board has a disposal margin area formed so as to surround the entire wiring board area on the outer periphery thereof, and the disposal margin area is formed in the inside thereof. Since a frame-like conductor layer that surrounds the entire wiring board area and is electrically connected to the wiring conductor formed on the main surface of the wiring board area through the through-hole is formed, The board is easier to handle, and the ceramic mother board, in which square frame-like wiring board areas are arranged vertically and horizontally, is electrically integrated through a frame-like conductor layer formed in the disposal margin area. Therefore, it is possible to more easily form the plating uniformly on each wiring conductor in the wiring board region. Further, even if the dividing groove is formed along the boundary of the wiring board area on the main surface of the ceramic mother board, the wiring board area (wiring conductor, etc.) and the frame-like conductor layer formed in the disposal margin area are metallized layers. Are connected by the through-holes deposited, and stable electrical connection can be achieved regardless of the depth of the dividing groove.

  Next, the multi-piece wiring board of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1A is a plan view showing an example of an embodiment of a multi-piece wiring board according to the present invention, and FIG. 1B is a cross-sectional view taken along line X-X ′ of FIG. FIG. 2 is an enlarged perspective view of a metallized layer portion of a wiring board region formed by dividing the multi-cavity wiring board shown in FIG. In the figure, 1 is a recess for storing electronic components, 2 is a ceramic mother board in which square-shaped wiring board areas are arranged vertically and horizontally, 3 is a wiring board area, and 4 is across the boundary of the wiring board area 3. The formed through holes, 5 is a wiring conductor, 6 is a metallized layer deposited on the inner surface of the through hole 4, and 10 is a groove formed by dividing the through hole 4 into two.

  The ceramic mother board 2 is made of a ceramic material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, or a glass ceramic. For example, a plurality of insulating layers made of such ceramic materials are laminated. It is formed by doing.

  If the ceramic mother substrate 2 is made of, for example, an aluminum oxide sintered body, raw powders such as aluminum oxide and silicon oxide are formed into a sheet shape together with an organic solvent and a binder to produce a plurality of ceramic green sheets. The ceramic green sheet is punched to be processed into a predetermined shape and size, and is laminated up and down to form a laminated body, which is formed by firing at a high temperature (about 1500 to 1600 ° C.).

  In the ceramic mother board 2, wiring board regions 3 are arranged vertically and horizontally, and dividing grooves 9 are formed along these boundary lines. Then, a stress is applied to the ceramic mother board 2 along the dividing grooves 9 to cause the ceramic mother board 2 to be broken, whereby the wiring board regions 3 are divided.

  The dividing grooves 9 are normally formed on the upper and lower surfaces of the ceramic mother board 2 so as to be at the same position in plan view. This is to reliably divide each wiring board region 3 of the ceramic mother board 2 without causing defects such as burrs and burrs.

  Such dividing grooves 9 are formed by, for example, pressing a cutter blade or a die into the upper and lower surfaces of the ceramic green sheet laminate as the insulating layers of the ceramic mother substrate 2 to make a cut. Further, the depth of the dividing groove 9 is set to about 20 to 70% with respect to the thickness of the ceramic insulating layer of the ceramic mother substrate 2 in order to prevent cracks, burrs, and chipping during division. The The dividing groove 9 is formed so as not to reach the center of the thickness of the ceramic mother board 2 in order to prevent the ceramic mother board 2 from being divided into the wiring board regions 3 during handling.

  The wiring board region 3 has a function of airtightly accommodating electronic components (not shown), and is usually a square box shape, and has a mounting portion for mounting the electronic components at the center of the upper surface thereof. In addition, a semicircular groove 10 is provided on the outer peripheral portion in a top view.

  Such a groove 10 is formed by forming a through hole 4 in the ceramic mother substrate 2 so as to straddle the divided groove 9. That is, when the wiring substrate region 3 is divided, the through hole 4 is also divided into two to form the grooves 10.

  Further, a wiring conductor 5 is attached from the inside of the recess 1 of the wiring board region 3 to the through hole 4 on the side surface, and an electrode of an electronic component is bonded to a portion of the wiring conductor 5 exposed to the inside of the recess 1. It is electrically connected via a wire or the like.

  The wiring conductor 5 is made of a metal material such as tungsten, molybdenum, copper, or silver. For example, if the wiring conductor 5 is made of tungsten, a paste of tungsten is applied on the surface of the ceramic green sheet serving as each insulating layer of the wiring board region 3. It can be formed by printing and applying to a pattern and baking it integrally.

  Further, a metallized layer 6 is deposited on the inner surface of the through hole 4, and the same metal material as that of the wiring conductor 5 is used.

  The metallized layer 6 functions to electrically connect the wiring conductors 5 of the adjacent wiring board regions 3 to each other.

  Between the wiring substrate regions 3 adjacent to each other, the wiring conductors 5 are electrically connected to each other by depositing a plating layer on the exposed surface of the wiring conductor 5 by an electrolytic plating method as will be described later. This is because a current for plating is supplied to the wiring conductor 5 in each wiring board region 3 in such a case. Therefore, it is necessary to form the metallized layer 6 continuously on the inner periphery of the through hole 4 between the adjacent wiring board regions 3.

  The metallized layer 6 also functions as a conductor for connecting the wiring conductor 5 and the external connection conductor 7, and connects the external connection conductor 7 to the circuit conductor of the external electric circuit board via solder or the like. The electronic component housed inside and connected to the wiring conductor 5 is electrically connected to the external electric circuit via the metalizing layer 6 and the external connection conductor 7 attached to the inner surface of the wiring conductor 5 and the through hole 4. Connected.

  Further, a rectangular frame-shaped sealing metallization layer 8 is attached to the outer periphery of the upper surface of the wiring board region 3 so as to surround the recess 1, and the sealing metallization layer 8 is at least one of the metallization layers 6. Connected to one.

  The sealing metallization layer 8 functions as a base metal for joining a lid (not shown) on the wiring board region 3, and is a rectangular flat plate lid made of a metal such as iron-nickel-cobalt alloy, for example. The lid is bonded onto the wiring board region 3 by bonding the body to the sealing metallization layer 8 via the brazing material. The sealing metallization layer 8 is connected to one of the metallization layers 6 so that it can be electrically grounded, for example.

  Here, as shown in FIG. 2, the metallized layer 6 is formed so that the thickness is gradually changed over the entire circumference so that the portion farthest from the dividing groove in the cross section is the thickest, and the portion in contact with the dividing groove is the thinnest. Has been.

  As a result, the strength of the metallized layer 6 as a film can be increased by the thick portion (the portion where the thickness of the metallized layer 6 is thick and far from the dividing groove), and the ceramic mother board 2 is divided into each wiring board region 3. In this case, it is possible to prevent peeling of the metallized layer 6 that occurs when the adjacent wiring board regions 3 are pulled to both sides. Further, when the ceramic mother substrate 2 is divided by the thin portion of the metallized layer 6 (the portion where the thickness of the metallized layer 6 is thin and in contact with the dividing groove), the metallized layer 6 can be divided into two vertically in a favorable manner. It is possible to effectively suppress the crack from proceeding to the interface between the metallized layer 6 and the ceramic mother substrate 2 and peeling off the metallized layer 6.

  In this case, when the ceramic mother board 2 is divided into the respective wiring board regions 3, the cracks that have advanced from the tip of the dividing groove 9 can be linearly advanced to the thinnest part of the metallized layer 6. The crack can be divided into two vertically without being bent. As a result, since the progress of cracks does not vary, it is possible to prevent the metallized layer 6 from peeling off more reliably. This is because once the direction of the crack is determined, the crack tends to advance in that direction.

  Therefore, the metallized layer 6 on the inner surface of the through-hole 4 is divided from the front end of the upper split groove 9 to the front end of the opposing split groove 9, which effectively prevents the metallized layer 6 from peeling off. is there.

  Further, when the ceramic mother board 2 is divided into the respective wiring board regions 3, even if the cracks progressing from the front ends of the dividing grooves 9 meander until they progress in the direction of the front ends of the opposing dividing grooves 9, Since the metallized layer 6 deposited on the inner surface of 4 has a thick portion so as to be formed thicker toward the portion farthest from the dividing groove 9 in the cross section, it has strength as a film. , It does not peel off from the inner surface of the through-hole 4 and turn up.

  The wiring conductor 5, the metallized layer 6, the external connection conductor 7 and the sealing metallized layer 8 are preferably coated with a plating layer such as nickel or gold on the exposed surface. Thereby, oxidation of the wiring conductor 5, the metallized layer 6, the external connection conductor 7 and the sealing metallized layer 8 can be effectively prevented, the bonding property of the bonding wire to the wiring conductor 5, and the sealing It is possible to improve the wettability of the brazing material with respect to the metallized layer, and to make a multi-piece wiring board capable of forming a wiring board with excellent reliability such as electrical connection of electronic parts. it can.

  Such a plating layer is obtained by holding a multi-piece wiring board with a plating jig, and electrically connecting the wiring conductor 5 from a terminal of the jig to the wiring conductor 5 in a plating solution. It is formed.

  Further, the metallized layer 6 is preferably symmetrical with respect to the extension line of the dividing groove 9 in the cross-sectional shape over the entire circumference. Thereby, since the film strength of the metallized layers 6 deposited on the inner walls of the through holes 4 of the adjacent wiring board regions 3 can be made uniform, the adjacent wiring board regions 3 are more effectively arranged on both sides. It is possible to prevent the metallized layer 6 from being peeled off by being pulled.

  Thus, as a method of forming the metallized layer 6 having the thin portion and the thick portion on the inner surface of the through hole 4 of each insulating layer, for example, the method is manufactured as follows. First, after forming a through hole to be a through hole 4 at a predetermined position of the ceramic green sheet to be each insulating layer, the ceramic green sheet is printed on the printing table so that the through hole coincides with the suction hole provided in the printing table. Placed on. Thereafter, the elliptical opening hole formed in the screen printing plate making and the through hole of the ceramic green sheet overlap with the through hole of the ceramic green sheet, and the short diameter of the elliptical opening hole is divided into the dividing grooves 9. The plate making for screen printing is placed so as to be orthogonal to each other. The metallized paste such as tungsten can be formed by sucking and removing a part of the metallized paste from the suction hole of the printing table while pouring the metallized paste into the through hole 4.

  At this time, by adjusting the viscosity of the metallized paste to be used, it is possible to form the ceramic green sheet so that the portion farthest from the dividing groove 9 is thick and the portion in contact with the dividing groove 9 is thinnest. For example, in order to make the thickness of the metallized layer 6 deposited in the inside of the through hole after printing be about 30 to 40 μm at a portion farthest from the dividing groove 9 and about 10 to 15 μm at a portion in contact with the dividing groove 9, What is necessary is just to use a thing with a viscosity higher than the metallized paste which forms the wiring conductor 5. FIG. Then, by laminating and firing a plurality of these ceramic green sheets, the above through-holes overlap to form the through-hole 4, and the innermost part of the innermost part of the cross-section is the thickest in the divided groove 9. The metallized layer 6 is deposited and formed by gradually changing the thickness over the entire circumference so that the contacted portion becomes the thinnest.

  Here, the thickness of the metallized layer 6 deposited on the inner surface of the through-hole 4 of each insulating layer is 30 to 40 μm at the portion farthest from the dividing groove 9 and about 10 to 15 μm at the portion in contact with the dividing groove 9. It is desirable. When the thickness is less than 10 μm, it is difficult to electrically and reliably connect the wiring conductor 5 and the metallized layer 6 formed in each insulating layer. If the thickness exceeds 40 μm, the apparent opening diameter after the metallized layer 6 is formed becomes small, and the plating solution is not sufficiently circulated through the metallized layer 6 formed on the inner surface of the through hole 4. This is because it is difficult to be worn.

  Further, in the multi-cavity wiring board of the present invention, the ceramic mother board 2 has a disposal margin area 11 formed so as to surround the entire wiring board area 3 on the outer peripheral portion thereof. It is preferable that a frame-like conductor layer 12 surrounding the entire wiring board region 3 is formed, which is electrically connected to the wiring conductor 5 formed on the main surface of the wiring board region 3 through the through hole 4. .

  The disposal allowance area 11 makes it easier to handle the ceramic mother board 2 and the rectangular frame-like wiring board areas 3 are arranged vertically and horizontally through the frame-like conductor layer 12 formed in the discard allowance area 11. The formed ceramic mother board 2 can be electrically connected integrally, and it becomes even easier to uniformly deposit and form the plating on each wiring conductor 5 in the wiring board region 3. Even if the dividing groove is formed along the boundary of the wiring board region 3 on the main surface of the ceramic mother board 2, the frame-like conductor layer formed in the wiring board region 3 (wiring conductor 5 and the like) and the disposal margin region 11. 12 is connected by the through-hole 4 to which the metallized layer 6 is attached, and can be a stable electrical connection regardless of the depth of the dividing groove.

  For example, a lead wire for plating is led out and formed on the side surface of the ceramic mother substrate 2 from the frame conductor layer 12, and the terminal of the plating jig is connected to the lead portion of the lead wire, whereby the frame conductor layer 12 is formed. Thus, a plating current can be supplied to the wiring conductors 5 of the respective wiring board regions 3 at once.

  Thus, according to the multi-piece wiring board of the present invention, when the ceramic mother board 2 is divided into the wiring board areas 3, the metallized layer 6 is peeled off due to the adjacent wiring board areas 3 being pulled to both sides. Therefore, it is possible to prevent disconnection or short-circuit due to peeling of the metallized layer 6 on the inner surface of the through-hole 4 and to provide an electronic device having excellent electrical reliability.

  It should be noted that the present invention is not limited to the examples of the above-described embodiments, and changes and modifications can be made without departing from the scope of the present invention.

(A) The top view which shows an example of embodiment of the multi-cavity wiring board of this invention, (b) is sectional drawing in the X-X 'line | wire of the multi-cavity wiring board of (a). FIG. 2 is an enlarged perspective view of a metallized layer portion of a wiring board region formed by dividing the multi-cavity wiring board of FIG. 1. (A) The top view of the conventional multi-cavity wiring board, (b) is sectional drawing in the Y-Y 'line | wire of the multi-cavity wiring board of (a). FIG. 4 is an enlarged perspective view of a metallized layer portion of a wiring board region formed by dividing the multi-cavity wiring board of FIG. 3.

Explanation of symbols

2 ... Ceramic mother board 3 ... Wiring board area 4 ... Through hole 5 ... Wiring conductor 6 ... Metallized layer 9 ... Dividing groove 11 ... Discard allowance area 12 ... Frame-shaped conductor layer

Claims (3)

Divided grooves are provided along the boundary of the wiring substrate region on the main surface of the ceramic mother substrate in which rectangular wiring substrate regions are arranged vertically and horizontally, and a plurality of metallized layers are deposited on the entire inner surface. A multi-piece wiring board in which a through-hole is formed so as to straddle the dividing groove, and the metallized layer has a thickest portion in the cross section that is the farthest from the dividing groove and a portion that is in contact with the dividing groove. A multi-cavity wiring board characterized in that the thickness gradually changes over the entire circumference so as to become thinner. 2. The multi-piece wiring board according to claim 1, wherein the metallized layer has a cross-sectional shape over the entire circumference symmetrical with respect to an extension line of the dividing groove. In the ceramic mother board, a margin area is formed on the outer periphery of the ceramic mother board so as to surround the entire wiring board area, and the discard margin area is a wiring formed on the main surface of the wiring board area. The multi-piece wiring according to claim 1 or 2, wherein a frame-like conductor layer is formed which is electrically connected to a conductor via the through hole and surrounds the entire wiring board region. substrate.

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