JP2019079835A - Ceramic substrate - Google Patents

Abstract

To provide a ceramic substrate capable of mounting electronic components accurately, electrically and reliably above multiple via conductors, even if the multiple via conductors are disposed relatively densely at a center side of a front surface of a ceramic substrate body.SOLUTION: A ceramic substrate 1 includes a substrate body 2 being obtained by laminating ceramic layers c1-c3, and having a rectangular configuration in a plan view and a front surface 3 and a rear surface 4 facing each other, and a mounting region 5 located at a center side of the surface 3 of the substrate body 2 in the plan view, and having multiple via conductors 7 disposed in the thickness direction of the substrate body 2. On the surface 3 of the substrate body 2, multiple dummy via conductors 8 formed in a thickness direction of the substrate body 2 are disposed at an outside of the mounting region 5 in the plan view, the mounting region 5 and the multiple dummy via conductors 8 are included on the surface 3 of the substrate body 2 in the plan view, and a recess 10 protruding to a rear 4 side of the substrate body 2 in a side view is provided.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a ceramic substrate in which a plurality of via conductors are relatively densely disposed on the center side in a plan view of the surface of a substrate body made of ceramic.

In general, a ceramic substrate is manufactured by printing or filling a conductive paste containing a metal powder on the surfaces of a plurality of ceramic green sheets and through holes provided in the ceramic green sheets, laminating the green sheets, and firing the same. ing. However, at the time of the firing, it is known that the resulting ceramic substrate is inadvertently warped due to the difference in the amount of contraction between the ceramic and the metal.
For example, a plurality of ceramic layers are laminated, and a plurality of wiring parts in which external wiring patterns, internal wiring patterns, and vias (via conductors) connecting these are formed, and along the periphery of the wiring parts By forming dummy vias (dummy via conductors) in the non-wiring portions, which are formed of rectangular frame-shaped non-wiring portions arranged, generation of careless warpage can be suppressed and yield in the mounting process of electronic components can be improved. A ceramic multilayer substrate is proposed (see, for example, Patent Document 1).

  By the way, on the center side of the surface of the substrate main body made of ceramic, a plurality of pads for mounting electronic components are formed on the surface, and directly below the respective pads in the thickness direction of the substrate main body. A plurality of via conductors disposed along are individually connected. Between the central side and the peripheral side of the surface of the substrate main body on which the plurality of via conductors are arranged relatively densely, the central side in plan view due to the difference in the amount of contraction in the firing step during manufacturing. The surface of the conductor contracts more along the thickness direction due to the contraction of the plurality of via conductors than the surface on the peripheral side. As a result, when the contraction amount of the via conductor is larger than the contraction amount of the ceramic, the concave portion convex on the opposite back surface side includes the plurality of via conductors in plan view on the center side of the surface. It is formed along the mounting area. When the recess is formed, the peripheral portion of the bottom surface of the electronic component to be mounted on the plurality of pads later contacts or approaches the inclined surface or the curved surface on the peripheral side of the recess, thereby requiring the electronic component. Can not be mounted in the posture and position of the device, and the electrical connection may be unstable. Furthermore, since the concave portion is formed by a curved surface, the connection height between the pad on the peripheral side close to the end of the concave portion and the pad on the central side is different, so There is a problem that connection reliability decreases.

JP, 2012-114183, A (pages 1 to 13, FIGS. 1 to 5)

  The present invention solves the problems described in the background art, and even if a plurality of via conductors are relatively densely arranged on the center side of a plan view on the surface of the substrate body made of ceramic, the plurality of vias It is an object of the present invention to provide a ceramic substrate on which an electronic component can be accurately and reliably mounted on the upper side of a conductor.

Means for Solving the Problems and Effects of the Invention

According to the present invention, in order to solve the above problems, dummy via conductors are disposed along the outside of the mounting region in which a plurality of via conductors are disposed on the surface of the substrate main body made of ceramic, whereby the mounting is performed in plan view. The idea is to create a recess which is wider than the bottom of the electronic component to be manufactured.
That is, the ceramic substrate (Claim 1) of the present invention is made of ceramic, and has a substrate main body having a rectangular front surface and a rear surface, which has a rectangular outer shape in plan view, and a central side in plan view of the front surface And a mounting region having a plurality of via conductors arranged and disposed along the thickness direction of the substrate body, wherein the mounting region is a plan view of the mounting region on the surface of the substrate body. A plurality of dummy via conductors formed along the thickness direction of the substrate body along the outer side are disposed, and the mounting region and the plurality of dummy via conductors on the surface of the substrate body in plan view are included, and side surfaces It is characterized by having a crevice which becomes convex on the back side of the above-mentioned substrate main body visually.

According to the ceramic substrate, the following effect (1) is obtained.
(1) On the surface of the substrate body, there is provided a mounting area in which a plurality of the via conductors are relatively densely arranged on the center side of the surface in plan view, and a plurality of via conductors are provided along the outside of the mounting area Dummy via conductors are disposed. Therefore, since the plurality of via conductors as well as the plurality of via conductors are contracted along their axial directions in the firing step at the time of manufacture, the mounting region and the above in the planar view are displayed on the surface of the substrate body. A recess is formed that includes a plurality of dummy via conductors located outside and that is relatively flat that is convex on the back surface side of the substrate body in a side view and that has a larger area than the mounting region of electronic components to be mounted later ing. Therefore, when the electronic component is mounted by brazing or the like with respect to the upper end surface of the plurality of via conductors or through a plurality of pads or the like joined to the upper end surface of each via conductor, Can be accurately and easily mounted in a required posture and position, so that electrical connection between each via conductor and the electronic component can be reliably obtained.

The ceramic is, for example, a high temperature fired ceramic such as alumina or aluminum nitride, or a low temperature fired ceramic such as glass-ceramic.
Further, the mounting area has a rectangular (square or rectangular) shape in plan view.
Further, the via conductor is made of tungsten (hereinafter, simply described as W) or molybdenum (hereinafter, simply described as Mo) when the substrate body is the above-mentioned high temperature sintered ceramic, and in the case of the above low temperature sintered ceramic Is made of copper or silver.
The dummy via conductor may be formed for each ceramic layer located at different depths in the same substrate body.
Furthermore, a pad protruding above the surface of the substrate body may be joined to the upper end surface of the via conductor.
The dummy via conductor is made of the same metal or the same metal as the via conductor.
Furthermore, the recess has a flat arc shape or a flat inverted trapezoidal shape in a side view.
In addition, the ceramic substrate may have a multi-piece form including a product region in which a plurality of the ceramic substrates are provided adjacent to each other vertically and horizontally in plan view.

The present invention also includes a ceramic substrate (Claim 2) in which the plurality of dummy via conductors are disposed at least along only the vicinity of the four corners in the mounting region in plan view.
According to this, the mounting area has a rectangular (square or rectangular) shape in a plan view, and the outlines of the plurality of via conductors disposed in the mounting area are substantially the same as the outlines of the mounting area in a plan view It is similar. Therefore, in the firing process at the time of manufacture, in the vicinity of the four corners of the mounting area, the via conductors are relatively dense, and the area where the via conductors exist (that is, the area where the contraction is large) and the via conductors do not exist. It is a boundary with a region (ie, a region with a small contraction). As a result, the four corners are relatively less likely to shrink than the other portions, and as described above, the plurality of dummy via conductors may be disposed only along the four corners in the mounting area in plan view. As a result, the ceramic substrate has a recess on the surface of the substrate body that is relatively wider than the mounting area of the same electronic component as described above. Therefore, it is possible to achieve the effect (1).

Furthermore, in the present invention, the substrate body is a laminate of a plurality of ceramic layers, and the upper surface of the dummy via conductor is exposed on the surface of the substrate body (Claim 3) Also included.
According to this, since the upper end surfaces of the plurality of dummy via conductors are exposed on the surface of the substrate main body, the surface side of the substrate main body on which the plurality of dummy via conductors are located is included in the firing step during manufacturing. The recess is formed at a position. As a result, the electronic component is accurately mounted via the balls (for example, solder balls) of the conductor or the pads joined in advance to the upper end surfaces of the plurality of via conductors located in the mounting area later. Can. Therefore, it is possible to reliably achieve the effect (1).
The plurality of dummy via conductors may penetrate through the uppermost ceramic layer having the surface of the substrate body or the ceramic layer and the middle ceramic layer adjacent thereto.

The present invention also includes a ceramic substrate (claim 4) in which the upper end surface of the dummy via conductor also serves as an alignment mark.
According to this, for example, when the mounting area is rectangular in plan view, four dummy via conductors whose upper end faces also serve as alignment marks are disposed at four corners which are extensions of two diagonal lines in the mounting area. Or, in the outer shape of the mounting area, four dummy via conductors also serving as alignment marks are arranged on the extension of each pair of middle lines passing through the middle points of the pair of opposing sides vertically and horizontally. It is illustrated that. As a result, at the time of mounting of an electronic component to be performed later, the position of each of the dummy via conductors can be confirmed by image processing using a CCD camera or the like, thereby enabling more accurate mounting. Therefore, the effect (1) can be more remarkably obtained by using the dummy via conductor also serving as the alignment mark in combination, and the mounting by image processing is also possible (hereinafter referred to as the effect (2)).
The dummy via conductor which also serves as the alignment mark may be the same as the via conductor, or may have a color added to the upper end surface thereof by plating or painting.

In addition, in the present invention, the substrate body is a laminate of a plurality of ceramic layers, and the dummy via conductor is formed in the middle ceramic layer of the substrate body (Claim 5) Also included.
According to this, since the plurality of dummy via conductors are formed in the middle ceramic layer of the substrate main body, shrinkage during firing is less likely to become healthy on the front surface side and the back surface side of the substrate main body. As a result, a ceramic substrate having on the center side of the surface of the substrate body the concave portion which is wider than the mounting region in plan view and which suppresses the inclination of the inclined surface located on the peripheral side or the steepness of the curved surface. It is done. Therefore, it becomes a ceramic substrate which can obtain the said effect (1) more reliably.
Further, according to the embodiment, the electronic component can be reliably prevented from being mounted in the wrong area in confusion with the pad for mounting (hereinafter referred to as effect (3)).
Furthermore, according to the above-described embodiment, since the via conductor is not exposed to the outside, the amount of use of a nickel film or a gold film by electrolytic plating described later can be reduced (hereinafter referred to as effect (4)).
The dummy via conductor is, for example, in the form of a relatively vertically long penetrating the uppermost ceramic and the middle ceramic layer in the vicinity of the four corners of the mounting area, and in the middle position in each of the four sides of the mounting area. It is good also as a comparatively short form which penetrates only a ceramic layer.

(A) is a plan view showing a ceramic substrate according to one embodiment of the present invention, (B) is a vertical sectional view taken along the arrow of XX in (A), (C) is a state in which electronic components are mounted FIG. (A) is a partial plan view of the above-mentioned ceramic substrate containing a dummy via conductor of a different arrangement, (B) is a partial plan view of the above-mentioned ceramic substrate containing a dummy via conductor of application form. FIG. 7 is a vertical cross-sectional view of the ceramic substrate including dummy via conductors of different forms of arrangement. (A) is a partial plan view of the above-mentioned ceramic substrate containing a dummy via conductor of a different application form, (B) is a top view of the above-mentioned ceramic substrate containing a dummy via conductor of a further different application form.

Hereinafter, modes for carrying out the present invention will be described.
FIG. 1 (A) is a plan view showing a ceramic substrate 1 according to an embodiment of the present invention, and FIG. 1 (B) is a vertical cross-sectional view taken along the arrow X-X in FIG. 1 (A).
The ceramic substrate 1 is, as shown in FIGS. 1 (A) and 1 (B), a substrate body 2 having a square (rectangular) outer shape in plan view and having a front surface 3 and a back surface 4 facing each other; And a mounting region 5 having a plurality of via conductors 7 disposed along the thickness direction of the substrate main body 2 and located on the center side in plan view of the surface 3 of FIG.
The substrate body 2 is formed by integrally laminating three ceramic layers (ceramics) c1 to c3. The ceramic layers c1 to c3 are mainly made of alumina, for example.

Further, the mounting area 5 is a virtual area for arranging an electronic component to be mounted later on the surface 3 of the substrate main body 2 and has substantially the same size as the bottom surface of the electronic component. On the surface 3 in the mounting area 5, the upper end surfaces of the plurality of via conductors 7 arranged in a grid shape in plan view are exposed. The via conductor 7 is made of W or Mo and penetrates the ceramic layers c1 and c2 of the top layer and the middle layer of the substrate body 2.
The plurality of via conductors 7 are arranged relatively densely as compared with the peripheral side of the surface 3 of the substrate body 2 in plan view. The plurality of via conductors 7 may be arranged in a checkered (staggered) pattern in plan view.
Furthermore, as shown in FIGS. 1 (A) and 1 (B), the disk-shaped pads 9 protruding above the surface 3 of the substrate body 2 are individually bonded in advance to the upper end surfaces of the plurality of via conductors 7. It is done. The pad 9 is also made of W or Mo, and the surface exposed to the outside is coated with a nickel film and a gold film (both not shown) by electrolytic plating.

An inner layer wiring (not shown) is appropriately formed between the ceramics c1 to c3, and the inner layer wiring is connected to any of the via conductors 7 and penetrates the middle and lower ceramic layers c2 and c3. A plurality of external connection terminals (not shown) formed on the back surface 4 of the substrate body 2 are also electrically connected via via conductors (not shown). The inner layer wiring, the via conductor, and the external connection terminal are also made of W or Mo.
Further, as shown in FIGS. 1A and 1B, on the surface 3 of the substrate body 2, along the outer side of the mounting region 5 in plan view, the plurality of dummy via conductors 8 have a rectangular frame shape and substantially It is arranged at equal intervals. The dummy via conductor 8 is also made of W or Mo, and both pass through the ceramic layers c1 and c2. The dummy via conductor 8 is conductive at the time of manufacture, including W powder or Mo powder filled in each of the plurality of via holes formed in the ceramic green sheet by the same punching as in the case of the via conductor 7. The paste is fired.

  In addition, as shown in FIGS. 1A and 1B, the surface 3 of the substrate body 2 has a rectangular shape including the mounting region 5 and the plurality of dummy via conductors 8 in a plan view, and a side surface A concave portion 10 having a shallow convex shape is provided on the side of the back surface 4 of the substrate body 2 as viewed. When the three-layered ceramic green sheet laminate to be the substrate body 2 is fired, the recess 10 has an axis of the unfired plurality of via conductors 7 and a plurality of dummy via conductors 8 after firing. It is formed as a result of contraction along the direction. Depending on the condition of the contraction and the like, the plan view may be similar on the central side of the back surface 4 of the substrate main body 2 and may be formed with a smaller, shallow recess (not shown) substantially in line symmetry. .

FIG. 1C is a vertical sectional view similar to the above, showing a state in which the electronic component 12 is mounted on the mounting area 5 on the surface 3 of the substrate body 2.
As illustrated, the electronic component 12 in the form of a flat rectangular parallelepiped as a whole is formed of solder or the like not shown above the plurality of pads 9 joined to the upper ends of the plurality of via conductors 7 located in the mounting area 5. Implemented via Moreover, the recess 10 is also formed in the region including the plurality of dummy via conductors 8 in the surface 3 of the substrate body 2, and the recess 10 is relatively flat at the center side in plan view, and the center side The peripheral side has a relatively steep curved surface. As a result, as shown in FIG. 1C, the entire periphery of the bottom surface of the electronic component 12 is located inside the recess 10, and a plurality of not-shown externals provided on the bottom surface of the electronic component 12 The electrodes can be individually conducted to the plurality of via conductors 7 via the solder or the pad 9.
Therefore, according to the ceramic substrate 1 as described above, it becomes easy to mount the electronic component 12 at a predetermined position and posture with high accuracy (the effect (1)).

FIG. 2A is a partial plan view showing the ceramic substrate 1 including the dummy via conductors 8 in an arrangement different from that described above.
As shown in FIG. 2A, a mounting area 5 having a plurality of via conductors 7 disposed in the same manner as described above is located on the center side of the surface 3 of the substrate body 2 in plan view. A plurality of dummy via conductors 8 are arranged at substantially equal intervals along the vicinity of the outside of the four corners of the region 5. The above-described shrinkage during firing tends to be relatively unlikely to occur near the four corners where two sides are adjacent to each other than the middle side of each side of the mounting area 5 in the mounting area 5 having a rectangular shape in plan view.
Therefore, the above effect (1) can be obtained also by the above-described form in which the plurality of dummy via conductors 8 are disposed only in the vicinity of the four corners outside the mounting area 5.
In FIG. 2A, of the five dummy via conductors 8 in the four corners having an L shape in plan view, the dummy via conductors 8 located at each corner may be omitted.

FIG. 2 (B) is a partial plan view of the ceramic substrate 1 showing an application of the embodiment shown in FIG. 2 (A).
As shown in FIG. 2B, the mounting area 5 similar to the above is located on the center side of the surface 3 of the substrate main body 2 and a plurality of the mounting areas 5 are provided along the outside only of the four corners of the mounting area 5. The dummy via conductor 8 is disposed in an L shape in plan view. Among the five dummy via conductors 8 at every four corners, each of which has an L shape in a plan view, a dummy via conductor 8a which doubles as an alignment mark for easy image recognition in a plan view. It is The dummy via conductor 8a is, like the other dummy via conductors 8, in the form in which the outermost layer of the upper end surface is coated with a gold film by plating, for example, a coating film having a bright color such as white The coating may be applied.
As illustrated, the four dummy via conductors 8 a are located at positions where two diagonal lines (virtual lines) in the mounting area 5 individually pass through the center of the mounting area 5 in plan view. Therefore, when the electronic component 12 is mounted on the mounting area 5, the mounting accuracy of the electronic component 12 is previously recognized by recognizing the positions of the four dummy via conductors 8a with a CCD camera (not shown) or the like. It is possible to increase the
Therefore, according to the above aspect, it is possible to obtain the effects (1) and (2).

FIG. 3 is a vertical cross-sectional view of the ceramic substrate 1 including the dummy via conductors 8b of different forms of arrangement.
As shown in FIG. 3, in the present ceramic substrate 1, the similar mounting area 5 is located on the center side of the surface 3 of the substrate body 2 in plan view, and along the outside of the mounting area 5, an intermediate layer is provided. A plurality of dummy via conductors 8b penetrating only the ceramic layer c2 are disposed. The dummy via conductor 8b which is not exposed on the front surface 3 and the back surface 4 of the substrate body 2 may be formed along the entire outer periphery of the mounting region 5 in a plan view or only near the four corners of the mounting region 5 It is good also as a form arrange | positioned.
By using the dummy via conductor 8b, as shown in FIG. 3, the concave portion 10 formed on the surface 3 side of the substrate main body 2 is more relieved of the steepness in the curved surface of the peripheral portion, so the effect (1) ) Can be obtained more reliably.
In addition, the effects (3) and (4) can be exhibited together.

FIG. 4A is a partial plan view of the ceramic substrate 1 including dummy via conductors 8 and 8b of different application forms.
As shown in FIG. 4A, in the present ceramic substrate 1 as well, the mounting region 5 similar to the above is located on the center side of the surface 3 of the substrate body 2 in a plan view. A plurality of dummy via conductors 8 penetrating the ceramic layers c1 and c2 in the vicinity of the four corners along the outer side of the mounting area 5 in plan view and having the upper end surface exposed on the surface 3 of the substrate body 2 are disposed. In addition, a plurality of dummy via conductors 8b which penetrate only the ceramic layer c2 and are not exposed to the surface 3 are disposed in the middle of each side of the mounting area 5.

As described above, by arranging the plurality of dummy via conductors 8 in the vicinity of the four corners of the mounting area 5 and arranging the plurality of dummy via conductors 8 b in the middle of each side of the mounting area which is between them. In the contraction process after firing, in the vicinity of the four corners of the mounting area 5, a sharp curved surface along the thickness direction of the substrate body 2 is formed every corner of the recess 10 and each mounting area 5 It is possible to form a recess 10 having a relatively gentle curved peripheral portion adjacent to each middle position of the side.
Therefore, the ceramic substrate 1 of the above-mentioned form also has the above effect (1).
In FIG. 4A, the dummy via conductors 8a which also serve as alignment marks may be separately added and arranged near the four corners of the recess 10.

FIG. 4B is a plan view of the ceramic substrate 1 including the dummy via conductors 8 and 8a of further different application forms.
As shown in FIG. 4B, in the present ceramic substrate 1 as well, the mounting region 5 similar to the above is located on the center side of the surface 3 of the substrate body 2 in a plan view. A plurality of dummy via conductors 8 are arranged in a zigzag form along the outside of the mounting area 5 in a plan view along the outside of the mounting area 5 in the inner and outer two rows in the vicinity of each of the four corners. A plurality of dummy via conductors 8 are arranged in a line along the inner side closer to the mounting area 5 every middle of the side.

Further, as shown in the drawing, one dummy via conductor 8a which doubles as an alignment mark is disposed outside each corner of the mounting area 5. As shown in FIG.
According to the embodiment as described above, the ceramic substrate 1 can be provided with the recess 10 having a relatively large area on the center side of the plan view of the surface 3 of the substrate body 2 and the effects (1), ( 2) can be played.
The plurality of dummy via conductors 8 may be arranged in two or more inner and outer rows along the entire outer periphery of the mounting area 5 in a plan view. In this case, the plurality of dummy via conductors 8 are not limited to the zigzag shape in plan view, and may be arranged at each grid position.
Further, the dummy via conductor 8 a may be a normal dummy via conductor 8.

The present invention is not limited to the embodiments described above.
For example, the ceramic constituting the substrate body 2 may be, for example, a high temperature fired ceramic such as aluminum nitride or mullite, or a low temperature fired ceramic such as glass-ceramic. In the latter case, copper or silver is applied to the conductors such as the via conductor 7, the dummy via conductors 8, 8 a and 8 b, and the pad 9.
Further, the substrate body 2 may be a laminate of two ceramic layers or four or more ceramic layers. For example, in the case of a substrate body 2 composed of four ceramic layers, the via conductor 7 and the dummy via conductors 8 and 8a are adjacent only to the uppermost ceramic layer having the surface 3 or the uppermost ceramic layer. The dummy via conductor 8b may penetrate through one or both of the two ceramic layers in the middle layer.

Furthermore, the front surface 3 and the back surface 4 of the substrate body 2 may have a rectangular shape facing each other in plan view.
In addition, a mounting area 5 may be provided on the center side of the surface 3 of the substrate body 2 in which the outer shape in plan view has a rectangular shape. In this case, the dummy via conductor 8 (including the dummy via conductors 8a and 8b) may be disposed only along the outside of the pair of opposing short sides among the sides forming the rectangular shape, or It is recommended that the pitch provided along the outside of the pair of short sides be smaller than the pitch provided along the outside of the pair of long sides facing each other.
Furthermore, the pad 9 may be omitted, and the upper end surface of the via conductor 7 may be exposed to the surface of the substrate body 2.

The dummy via conductor 8a also serving as the alignment mark is disposed at four positions outside each of the intermediate positions on each side of the mounting area 5 having a rectangular shape in plan view, or the corner of the mounting area 5 It is good also as a form arrange | positioned in any three places in each.
In addition, the recess 10 has a substantially similar shape surrounding the mounting area 5 whose plan view is rectangular, and the middle of each side is gently curved toward the periphery or center of the surface 3 It may be

  According to the present invention, even if a plurality of via conductors are relatively densely arranged on the center side of the surface of the substrate body made of ceramic, the electronic component is accurately followed and located above the plurality of via conductors. It is possible to reliably provide a ceramic substrate that can be reliably mounted electrically.

1... Ceramic substrate 2 ........ Substrate body 3 ........ Surface 4 ........ Back surface 5 ........ Mounting area 7 ........ Via conductor 8, 8a, 8b ... Dummy via conductor 10 ..... Concave portion c1 to c3 ... Ceramic layer (ceramic)

Claims (5)

A substrate main body made of ceramic, having a rectangular outer shape in plan view and opposing front and back surfaces;
A ceramic substrate comprising: a mounting area having a plurality of via conductors located on the center side in plan view of the surface of the substrate body and disposed along the thickness direction of the substrate body,
A plurality of dummy via conductors formed along the thickness direction of the substrate body along the outer side of the mounting area in plan view are disposed on the surface of the substrate body.
The mounting area and the plurality of dummy via conductors on the surface of the substrate body in a plan view, and a concave portion convex on the back surface side of the substrate body in a side view
A ceramic substrate characterized by The plurality of dummy via conductors are disposed at least along only the vicinity of the four corners in the mounting region in plan view.
The ceramic substrate according to claim 1, characterized in that: The substrate body is formed by laminating a plurality of ceramic layers, and the upper surface of the dummy via conductor is exposed on the surface of the substrate body.
The ceramic substrate according to claim 1 or 2, characterized in that The upper end surface of the dummy via conductor also serves as an alignment mark.
The ceramic substrate according to claim 3, characterized in that: The substrate body is formed by laminating a plurality of ceramic layers, and the dummy via conductor is formed in the middle ceramic layer of the substrate body.
The ceramic substrate according to claim 1 or 2, characterized in that

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