JP6795441B2 - Ceramic wiring board and its manufacturing method - Google Patents

Description

The present invention relates to a ceramic wiring board that can be used for a CMOS package, a CCD package, a crystal device package, and the like, and a method for manufacturing the same.

Conventionally, tungsten and molybdenum are known as conductors used for wiring of ceramic wiring boards (see Patent Document 1).
Further, as a ceramic wiring board used for a ceramic package or the like, a ceramic wiring board having a relatively large diameter through hole (cavity) penetrating in the thickness direction of the ceramic substrate is known.

Japanese Unexamined Patent Publication No. 2001-77540

By the way, some ceramic wiring boards having the above-mentioned through holes have a shape in which the tip portion (that is, the open end) through which the through hole opens is popped up. That is, the open end of the through hole may have a shape protruding outward in the thickness direction from the main surface of the ceramic wiring board.

When a ceramic wiring board having such a shape is placed on a base, for example, a portion protruding outward from the main surface of the ceramic wiring board (that is, a protruding convex portion) is placed on the base. When present on the side surface, a load may be applied to the convex portion, and the convex portion made of ceramic may be chipped to generate a foreign substance.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to eliminate a convex portion to which a load is applied to an open end of a through hole, at least on a surface mounted on a base. It is an object of the present invention to provide a ceramic wiring board capable of suppressing the occurrence of defects due to the above and a method for manufacturing the same.

(1) The first aspect of the present invention is a ceramic having a through hole penetrating in the thickness direction, a ceramic substrate containing a ceramic as a main component, and a plurality of metal layers arranged inside the ceramic substrate. It is related to a wiring board.

This ceramic wiring substrate has one or more first metal layers made of tungsten and one or more second metal layers made of molybdenum as metal layers, and also has a first metal layer and a second metal layer. Is arranged so that at least a part of it overlaps when viewed from the thickness direction.

Further, the total WG1 obtained by summing the product of the distance T1 from the center to the first metal layer in the thickness direction of the ceramic wiring substrate and the volume of the first metal layer for all the first metal layers and the thickness direction of the ceramic wiring substrate. The total MG2, which is the sum of the products of the distance T2 from the center to the second metal layer and the volume of the second metal layer for all the second metal layers, satisfies the following formula (1).

| (MG2 / WG1) x 100 | ≤200 ... (1)
(However, for the distances T1 and T2, one direction from the center is positive and the other direction is negative.)
In the formula (1), it is shown that the absolute value of (MG2 / WG1) × 100 is 200 (%) or less.

Further, the distance T1 from the center to the first metal layer in the thickness direction of the ceramic wiring board and the distance T2 from the center to the second metal layer in the thickness direction of the ceramic wiring board are ceramic wiring boards along the thickness of the ceramic wiring board. The shortest straight line length parallel to the thickness direction from the center of the straight line length from the surface of the surface to the other surface facing the surface to the center of the thickness of each metal layer (first metal layer and second metal layer). Say that.

In the first aspect, the first metal layer made of tungsten and the second metal layer made of molybdenum are arranged as described above, and the total WG1 related to the first metal layer and the total MG2 related to the second metal layer are arranged. , The configuration satisfies the above formula (1). With such a configuration, when manufacturing a ceramic wiring board (that is, during firing), the open end (edge) of the through hole (cavity) enters the through hole side or is flat on at least one surface. It can be shaped.

That is, if the ceramic wiring board has the above-mentioned configuration, at least the opening end of the through hole on the surface mounted on the base does not have a protruding protrusion (bounce) protruding outward as in the conventional case. can do.

Therefore, even when a load is applied around the open end of the ceramic wiring board, it is possible to suppress the occurrence of a problem that the convex portion of the open end of the through hole is chipped and becomes a foreign substance as in the conventional case.
(2) In the second aspect of the present invention, alumina can be used as the ceramic.

This second aspect exemplifies a material suitable as a ceramic.
(3) In the third aspect of the present invention, the first metal layer and the second metal layer are arranged at different positions in the thickness direction of the ceramic substrate in a plane perpendicular to the thickness direction.

This third aspect exemplifies a suitable arrangement of the first metal layer and the second metal layer.
(4) The fourth aspect of the present invention relates to the method for manufacturing a ceramic wiring board according to any one of the first to third aspects.

In this method for manufacturing a ceramic wiring board, in the first step, a tungsten paste containing tungsten is applied to the surface of the first ceramic green sheet to form a first metal pattern to be a first metal layer.

In the second step, a molybdenum paste containing molybdenum is applied to the surface of the second ceramic green sheet to form a second metal pattern to be a second metal layer. The order of the first step and the second step may be reversed.

In the third step, one or more first ceramic green sheets and one or more second ceramic green sheets are laminated to form through holes containing a first metal pattern and a second metal pattern inside. A laminate having an opening is produced.

Further, when the first metal pattern or the second metal pattern is not formed on the green sheet which is the surface of the laminated body in the first step and the second step, after laminating by the third step, the surface of the laminated body or A step of forming a first metal pattern or a second metal pattern may be performed on the back surface.

In addition, when producing a laminated body, other ceramic green sheets may be laminated. Further, the laminated body is formed with an opening (that is, a hole through which) becomes the through hole after firing, and this opening may be formed after the laminated body is formed, or each ceramic. An opening to be the through hole may be formed in the green sheet, and the openings may be laminated to form a laminated body.

In the fourth step, the laminate (having an opening that serves as a through hole) is fired to produce a ceramic wiring board.
When the laminated body is produced in the first to third steps, the product of the distance T1'from the center to the first metal pattern in the thickness direction, which is the laminating direction of the laminated body, and the volume of the first metal pattern. The product of the total WG1'that is the sum of all the first metal patterns, the distance T2'from the center to the second metal pattern in the thickness direction of the laminate, and the volume of the second metal pattern is the product of all the second metal patterns. The total MG2'totaled for the metal pattern and the total MG2'satisfy the following equation (2).

| (MG2'/ WG1') x 100 | ≤200 ... (2)
(However, for the distances T1'and T2', one direction from the center is positive and the other direction is negative.)
In the formula (2), it is shown that the absolute value of (MG2'/ WG1') × 100 is 200 (%) or less.

Further, the distance T1 from the center to the first metal pattern in the thickness direction of the laminate and the distance T2 from the center to the second metal pattern in the thickness direction of the laminate are the distances T2 from the surface of the laminate along the thickness of the laminate. The shortest straight line length parallel to the thickness direction from the center of the straight line length to the other surface facing the surface to the center of the thickness of each metal pattern (first metal pattern and second metal pattern). To tell.

In the fourth aspect, the first metal pattern made of tungsten and the second metal pattern made of molybdenum are arranged as described above, and the total WG1'for the first metal pattern and the total MG2'for the second metal pattern are arranged. Satisfies the above formula (2).

Therefore, as is clear from the experimental examples described later, when the laminate is fired, it is possible to prevent at least one opening end of the opening of the laminate corresponding to the through hole of the ceramic wiring board from protruding outward. The shape can be such that the opening end enters the opening side (hanging shape).

That is, in the ceramic wiring board obtained by firing the laminated body, it is necessary to prevent at least one of the open ends of the through holes from being formed so as to protrude outward, so that the ceramic wiring board can enter the through holes or have a flat structure. Can be done.

Therefore, even when a load is applied around the open end of the through hole of the ceramic wiring board, it is possible to suppress the occurrence of a problem that the convex portion of the open end is chipped and becomes a foreign substance as in the conventional case.
Here, in the fourth aspect, the action of producing the above-mentioned effect will be described.

Due to the difference in sintering start temperature (grain growth start temperature) between ceramic (for example, alumina), tungsten, and molybdenum, the shape of the ceramic wiring substrate changes due to the temperature change in the firing process.

Here, of tungsten and molybdenum, molybdenum has a lower sintering start temperature and a larger sintering rate (that is, a larger shrinkage rate during sintering). Therefore, the shape after firing differs due to the change in volume balance between the types of conductor materials used for each layer of the ceramic green sheet (that is, tungsten and molybdenum).

Therefore, the moment that deforms the substrate generated by tungsten during firing and the moment generated by molybdenum during firing may be adjusted so that the open end hangs down.
That is, the above-mentioned WG1 and WG1'are tungsten moments (W moments)), and the above-mentioned MG2 and MG2'are molybdenum moments (Mo moments).

Specifically, the total WG1'for the first metal layer made of tungsten and the total MG2'for the second metal layer made of molybdenum may be arranged so as to satisfy the above formula (2).

As a result, the suppression of the surface to be hung down during firing is suppressed, and the open end is inserted into the through hole side.
<Hereinafter, each configuration of the present invention will be described>
-In addition to alumina, examples of ceramics include aluminum nitride, zirconia, and mullite. The main component indicates the highest content (for example, an amount exceeding 50% by volume).

The first metal layer made of tungsten has a tungsten content of 90% by volume or more in the first metal layer, and the second metal layer made of molybdenum has a molybdenum content of 90% by volume or more in the second metal layer. Is shown. That is, the first metal layer made of tungsten is a metal layer composed of 90% by volume or more of tungsten as described above, and this may include a case where tungsten is 100% by volume. The same applies to the second metal layer made of molybdenum.

-When the first metal layer is a layer having the same thickness, the volume of the first metal layer can be obtained by multiplying the area in a plan view seen from the thickness direction by the thickness. The same applies to the second metal layer.

It is a perspective view which shows the ceramic wiring board of an embodiment. (A) is a plan view of the ceramic wiring board of the embodiment, and (b) is a side view thereof. It is sectional drawing which shows the AA cross section of FIG. 2A enlarged. The method for manufacturing the ceramic wiring substrate of the embodiment is shown, (a) is a side view showing a first metal pattern formed on one ceramic green sheet, and (b) is a second side view showing a first metal pattern formed on another ceramic green sheet. A side view showing a metal pattern, (c) is a side view showing a laminated body, (d) is a cross-sectional view of a laminated body having an opening broken in the thickness direction, and (e) is a broken ceramic wiring substrate in the thickness direction. It is a sectional view. It is sectional drawing which shows the cross section which broke the frame part of the sample of an experimental example perpendicularly in the longitudinal direction. The experimental results are shown, (a) is a cross-sectional view schematically showing a cross section of the frame portion of the No. 1 sample, and (b) is a cross-sectional view schematically showing a cross section of the frame portion of the No. 2 to 4 samples. , (C) are sectional views schematically showing a cross section of the frame portion of the samples of Nos. 5 and 6.

Next, an embodiment of the ceramic wiring board of the present invention and a method for manufacturing the same will be described.
[1. Embodiment]
[1-1. Ceramic wiring board configuration]
First, the configuration of the ceramic wiring board of the present embodiment will be described with reference to FIGS. 1 and 2.

In this embodiment, a simple configuration in which the first metal layer and the second metal layer are each one layer and are provided in an annular shape in a plan view will be described as an example.
As shown in FIG. 1, the ceramic wiring board 1 of the present embodiment has a through hole 5 formed in the center of the flat plate-shaped ceramic substrate 3 so as to penetrate the ceramic substrate 3 in the thickness direction.

As shown in FIG. 2, the ceramic substrate 3 has an outer diameter of, for example, a square of about 10 mm square and a thickness of, for example, about 1 mm in a plan view. The ceramic substrate 3 is a substrate containing alumina as a main component (for example, 90% by volume of alumina).

Further, the through hole 5 provided so as to penetrate the axial center of the ceramic substrate 3 is a square having an inner diameter of, for example, about several mm square in a plan view.
That is, the ceramic substrate 3 has a square frame shape in a plan view, and the first frame portion 7 and the second frame portion 9 forming the sides extending in parallel in the left-right direction of FIG. 2 (a) and FIG. 2 (a). It is composed of a third frame portion 11 and a fourth frame portion 13 that form a side extending in the vertical direction of the above.

Further, inside the ceramic substrate 3, a first metal layer 15 made of tungsten (W) and a second metal layer 17 made of molybdenum (Mo) circulate around the through hole 5 in a plan view. It is arranged in a ring so as to surround it.

As shown in FIG. 2B, the first metal layer 15 and the second metal layer 17 are arranged in parallel when viewed from the direction perpendicular to the thickness direction.
In the ceramic wiring board 1, the lower side of FIG. 2B is the first main surface S1 which is the side (mounting surface) on which the base is mounted, and the opposite surface (exposed surface). Is the second main surface S2.

Here, the main surface (surface) on the side to be mounted on the base or the like is determined by the parts formed on each main surface, such as whether or not an external connection terminal (not shown) is formed. It is possible to do.
[1-2. Composition of 1st and 2nd metal layers]
Next, the configuration of the first metal layer 15 and the second metal layer 17, which are the main parts of the present embodiment, will be described.

As shown in FIG. 3, the first metal layer 15 is made of tungsten and has a flat plate shape having substantially the same thickness throughout itself. Here, the first metal layer 15 is a first metal layer 15 made of tungsten. Further, since the area of the first metal layer 15 is ME1 and the thickness is t1, the volume TA1 thereof is the area ME1 × the thickness t1.

The first metal layer 15 is arranged between the central CN in the thickness direction of the ceramic substrate 3 and the lower first main surface S1 in FIG. Specifically, it is arranged parallel to the plane direction of the ceramic substrate 3 (horizontal direction in FIGS. 3 and 2B) at a position at a distance T1 from the center CN. The distance T1 is the shortest straight line distance parallel to the thickness direction from the center CN to the center position of the thickness t1.

On the other hand, the second metal layer 17 is made of molybdenum and has a flat plate shape having substantially the same thickness throughout itself. Here, the second metal layer 17 is a second metal layer 17 made of molybdenum. Further, since the area of the second metal layer 17 is ME2 and the thickness is t2, the volume TA2 thereof is the area ME2 × the thickness t2. Here, for example, ME1 = ME2, t1 = t2, TA1 = TA2.

The second metal layer 17 is arranged between the central CN in the thickness direction of the ceramic substrate 3 and the second main surface S2 above FIG. Specifically, it is arranged at a distance T2 from the center CN and parallel to the plane direction of the ceramic substrate 3. Here, T1 = T2.

The distance T2 is the shortest straight line distance parallel to the thickness direction from the center CN to the center position of the thickness t2.
In particular, in the present embodiment, the first metal layer 15 and the second metal layer 17 are arranged so that at least a part of them overlap each other in a plan view (here, they are arranged so as to completely overlap each other).

Moreover, the total WG1 (here, here, the product SE1 of the distance T1 from the center CN of the ceramic wiring substrate 1 to the first metal layer 15 and the volume TA1 of the first metal layer 15 is summed for all the first metal layers 15). The product SE2 of the product SE2 of the distance T2 from the center CN of the ceramic wiring substrate 1 to the second metal layer 17 and the volume TA2 of the second metal layer is totaled for all the second metal layers. The total MG2 (here, only one second metal layer 17) satisfies the following formula (1).

| (MG2 / WG1) x 100 | ≤200 ... (1)
(However, for the distances T1 and T2, one direction from the center is positive and the other direction is negative.)
Further, in the present embodiment, when the ceramic wiring board 1 is defined by the central CN as the boundary between the first main surface S1 side and the second main surface S2 side, the first main surface S1 side is the second main surface. A larger amount (weight and volume) of tungsten is arranged than the surface S2 side.

Further, when the total WG1 on the first main surface S1 side and the total WG1 on the second main surface S2 side are compared, the total WG1 on the first main surface S1 side is the total on the second main surface S2 side. The value is larger than WG1 (here, WG1 = 0).

Therefore, as shown in FIG. 3, the opening end K1 of one of the through holes 5 (lower part of FIG. 3) of the ceramic wiring board 1 has a shape that enters the through hole 5 side (that is, a hanging shape).
That is, on the first main surface S1 side on the side where the first metal layer 15 made of tungsten is arranged, the opening end K1 of the through hole 5 has a gentle curve, and the inside of the through hole 5 from the opening end K1 side. It is shaped so that it goes in toward.

On the other hand, the opening end K2 on the other side of the through hole 5 (upper in FIG. 3) does not have a shape like the opening end K1 and does not have a shape that enters the through hole 5 side. That is, the second main surface S2 and the inner peripheral surface 5a of the through hole 5 are perpendicular to each other, and the entire surface of the second main surface S2 is flat. That is, the opening end K2 is not shaped like the opening end K1 so as to enter from the opening end K2 side toward the inside of the through hole 5.
[1-3. Manufacturing method of ceramic wiring board]
Next, the manufacturing method of the ceramic wiring board 1 of the present embodiment will be described with reference to FIG.

The ceramic wiring board 1 can be manufactured by separating each ceramic wiring board 1 from a plate-shaped base material in which a plurality of ceramic wiring boards 1 are arranged, but here, for the sake of simplification of the description. An example is given in the case of manufacturing one ceramic wiring board 1.

First, for example, a ceramic slurry is prepared using, for example, alumina as a main component and a binder resin, a solvent, or the like, and a plurality of ceramic green sheets 21 are prepared by the doctor blade method using the ceramic slurry.

Next, as shown in FIG. 4A, a first metal that becomes the first metal layer 15 by applying a tungsten paste containing tungsten to the surface of a certain ceramic green sheet 21 (first ceramic green sheet 21a). The pattern 23 is formed (first step). The term "tungsten paste" as used herein refers to tungsten as a metal component to which a paste-forming component such as a binder is added.

Further, as shown in FIG. 4B, a second metal pattern formed by applying a molybdenum paste containing molybdenum to the surface of another ceramic green sheet 21 (second ceramic green sheet 21b) to form a second metal layer 17. 25 is formed (second step). The molybdenum paste referred to here is molybdenum as a metal component to which a paste-forming component such as a binder is added.

Next, as shown in FIG. 4C, the first ceramic green sheet 21a on which the first metal pattern 23 is formed, the second ceramic green sheet 21b on which the second metal pattern 25 is formed, and the first and second The ceramic green sheet 21 that does not form the metal patterns 23 and 25 is laminated to produce a laminated body 27 containing the first metal pattern 23 and the second metal pattern 25 (third step).

After that, as shown in FIG. 4D, an opening 29, which is a through hole that becomes a through hole 5 after firing, is formed in the laminated body 27 by, for example, punching.
The shape of the laminate 27 is substantially similar to that of the ceramic wiring board 1, and is a square frame shape in a plan view.

Next, as shown in FIG. 4E, the laminated body 27 having the opening 29 is fired in, for example, an air atmosphere at a firing temperature of 1350 ° C. for 48 hours, and a ceramic substrate having a through hole 5 is formed. A ceramic wiring board 1 having a first metal layer 15 and a second metal layer 17 inside 3 is produced (fourth step).

In particular, in the present embodiment, when the laminated body 27 is produced in the above-mentioned first to third steps, the distance T1'from the center of the laminated body 27 in the thickness direction to the first metal pattern 23 and the first metal pattern WG1', which is the sum of the product SE1'with the volume TE1'for all the first metal patterns 23 (here, only one first metal pattern 23), and the second from the center in the thickness direction of the laminate 27. The product SE2'of the distance T2'to the metal pattern 25 and the volume TME2'of the second metal pattern 25 is totaled MG2 for all the second metal patterns 25 (here, only one second metal pattern 25). 'And so that the following equation (2) is satisfied.

| (MG2'/ WG1') x 100 | ≤200 ... (2)
(However, for the distances T1'and T2', one direction from the center is positive and the other direction is negative.)
In the present embodiment, the ceramic wiring board 1 having the configuration shown in FIG. 3 described above can be manufactured by such a manufacturing method. That is, it is possible to manufacture the ceramic wiring board 1 in which one opening end K1 of the through hole 5 of the ceramic wiring board 1 is formed so as to enter the through hole 5 side.

As described above, although the sizes of the laminated body 27 before firing and the ceramic wiring board 1 after firing are different, they have substantially similar shapes, so that the laminated body 27 satisfies the above formula (2). Satisfies the above formula (1) for the ceramic wiring board 1.

<Application example>
Further, unlike the above-described embodiment, when at least one of the first metal pattern 23 and the second metal pattern 25 is provided, the following procedure can be adopted in order to satisfy the above formula (2). ..

For example, first, the first main surface S1 side (lower side of FIG. 4 (c)) and the second main surface S2 (upper side of FIG. 4 (c)) are separated from the center in the thickness direction of the laminated body 27. In this case, the amount (weight and volume) of the tungsten paste is arranged on the first main surface S1 side more than on the second main surface S2 side.

Further, when the total WG1'on the first main surface S1 side and the total WG1'on the second main surface S2 side are compared, the total WG1'on the first main surface S1 side is the second main surface S2 side. The value is larger than the total WG1'in the above.

Then, in the case of setting in this way, it is confirmed whether or not the actual equation (2) is satisfied, and the size and arrangement of the first metal pattern 23 and the second metal pattern 25 are arranged so as to satisfy the equation (2). Should be corrected.
[1-4. effect]
Next, the effect of this embodiment will be described.

(1) The ceramic wiring board 1 of the present embodiment has a first metal layer 15 made of tungsten and a second metal layer 17 made of molybdenum inside the ceramic substrate 3 containing alumina as a main component. .. Further, the first metal layer 15 and the second metal layer 17 are arranged so that at least a part thereof overlaps in a plan view, and moreover, the above formula (1) is satisfied.

Therefore, the opening end K1 of the through hole 5 of the ceramic wiring board 1 has a shape that enters the through hole 5 side, and does not have a protrusion-like convex portion that projects outward as in the conventional case.
Therefore, even when a load is applied around the opening end K1 of the through hole 5 of the ceramic wiring board 1, a problem occurs in which the convex portion of the opening end K1 of the through hole 5 is chipped and becomes a foreign substance as in the conventional case. Can be suppressed.

(2) The method for manufacturing a ceramic wiring board of the present embodiment includes the above-mentioned first to fourth steps, and further satisfies the above formula (2).
That is, in the present embodiment, the total WG1'for the first metal pattern 23 made of tungsten and the total MG2'for the second metal pattern 27 made of molybdenum satisfy the above formula (2), so that the laminate 27 is fired. At that time, it is possible to prevent the opening end of the opening 29 of the laminated body 27 corresponding to the through hole 5 of the ceramic wiring board 1 from protruding outward, and the opening end can be formed into a shape that enters the opening 29 side. ..

Therefore, in the ceramic wiring board 1 obtained by firing the laminated body 27, it is possible to prevent the opening end K1 of the through hole 5 from being formed so as to protrude outward, and to enter the through hole 5 side. it can.

Therefore, even when a load is applied around the opening end K1 of the through hole 5 of the ceramic wiring board 1, it is possible to suppress the occurrence of a problem that the convex portion of the opening end K1 is chipped and becomes a foreign substance as in the conventional case [1]. -5. Correspondence of wording]
The ceramic wiring substrate 1, the ceramic substrate 3, the through hole 5, the first metal layer 15, the second metal layer 17, the first ceramic green sheet 21a, the second ceramic green sheet 21b, the first metal pattern 23, according to the present embodiment. The second metal pattern 25, the laminate 27, and the opening 29 are the ceramic wiring substrate, the ceramic substrate, the through hole, the first metal layer, the second metal layer, the first ceramic green sheet, and the second ceramic of the present invention, respectively. It corresponds to an example of a green sheet, a first metal pattern 23, a second metal pattern 25, a laminate 27, and an opening 29.
[1-6. Experimental example]
Next, an experimental example conducted for confirming the effect of the present invention will be described.

In this experimental example, samples (No. 1 to 6) of a laminated body of ceramic wiring boards were prepared so as to satisfy the conditions shown in Table 1 below.
In the ceramic wiring board of this sample, the first to seventh layers P1 corresponding to the first metal made of tungsten or the second metal made of molybdenum at each position (first to seventh planes H1 to H7) shown in FIG. ~ P7 was formed. The first to seventh metal layers are arranged in the first to fourth frame portions.

Further, here, the lower part of FIG. 5 is the first main surface side (mounting surface side), and the upper part of FIG. 5 is the second main surface side (exposed surface side), which is the center in the thickness direction of the ceramic wiring board. From 0 point, the first main surface side is minus (-), and from 0 point, the second main surface side is plus (+).

Specifically, the first layer P1 is provided on the first plane H1 on the first main surface separated from the point 0 by a distance L1. The second layer P2 is provided on the second plane H2 separated from the 0 point by a distance L2. The third layer P3 is provided on the third plane H3 which is separated from the 0 point by a distance L3. The fourth layer P4 is provided on the fourth plane H4, which is separated from the 0 point by a distance L4. The fifth layer P2 is provided on the fifth plane H5, which is separated from the 0 point by a distance L5.

The length of each distance L1 to L5 is, for example, L1 = 0.3 mm, L2 = 0.25 mm, L3 = 0.20 mm, L4 = 0.15 mm, L5, taking No. 2 in Table 1 as an example. = 0.05 mm, and L1> L2> L3> L4> L5. In the case of the calculation of the above equation (2), the values of the distances L1 to L5 are calculated as minus.

On the other hand, the sixth layer P6 is provided on the sixth plane H6, which is separated from the 0 point by a distance L6. The seventh layer P7 is provided on the seventh plane H7 on the second main surface, which is separated from the 0 point by a distance L7.
The lengths of the distances L6 and L7 are, for example, L7 = 0.30 mm and L6 = 0.15 mm, and L7> L6, taking No. 2 in Table 1 as an example. In the case of the calculation of the above equation (1), the values of the distances L6 and L7 are calculated as plus.

Further, the first to fifth layers P1 to P5 have the same planar shape and cross-sectional shape along the thickness direction, and are arranged at the center in the width direction (horizontal direction in FIG. 5) of the frame portion. The thickness of the first to fifth layers P1 to P5 is 0.01 mm.

On the other hand, the sixth and seventh layers P6 and P7 have the same planar shape and cross-sectional shape along the thickness direction, and are arranged at positions shifted outward from the center in the width direction of the frame portion (left and right in FIG. 5). Has been done. The thickness of the sixth and seventh layers P6 and P7 is 0.01 mm.

Then, the state of the open end of the through hole of the ceramic wiring board was examined for each of the above-mentioned samples. The results are also shown in Table 1 and FIG. 6 below. The shape of the open end is shown in the broken line ellipse of FIG.

The W moment in Table 1 is the value of the total WG1, the Mo moment is the value of the total MG2, and the moment ratio is (MG2 / WG1) × 100 in the formula (1). Is the value of.

As described above, WG1 and MG2 are the sum of the values obtained by multiplying the volume by the distance in each of the layers (first to seventh layers).
Further, "hanging" in Table 1 means that the opening end has entered the through hole side, and "bounce" means that the opening end has a convex portion protruding outward, and "hanging to flat". "" Indicates that there is no convex portion protruding to the outside, and the situation is almost flat or very slightly penetrates into the through hole.

The unit of the numerical value for obtaining the W moment and the Mo moment is mm.

As is clear from Table 1 and FIG. 6 (a), since the sample of No. 1 satisfies the above formula (1), the first main surface side (lower side of FIG. 6 (a)) forming the opening is formed. ) Has no convex portion at the open end, and has a shape that is curved toward the through hole side.

Although there was a convex portion at the opening end on the second main surface side (upper side of FIG. 6A) forming the opening, there is no problem because the first main surface side is the mounting surface.
As is clear from Table 1 and FIG. 6 (b), since the samples of Nos. 2 to 4 satisfy the above formula (1), they are convex to the opening end on the first main surface side forming the opening. There was no part, and the shape was curved toward the through hole side.

Further, there was no convex portion at the opening end on the second main surface side forming the opening, and the second main surface was flat.
As is clear from Table 1 and FIG. 6 (c), since the samples of Nos. 5 and 6 do not satisfy the above formula (1), the opening end (that is, the mounting end) on the first main surface side forming the opening is formed. There was a convex part on the side of the surface.

Although there is no convex portion at the opening end on the second main surface side that forms the opening, since it is not a mounting surface, the problem caused by the convex portion on the mounting surface cannot be solved.
From the above results, by satisfying the above formula (1), it is possible to form a structure having no convex portion at the opening end of at least one main surface (that is, the main surface on the side mounted on the base). ..
Further, when the above formula (1) is satisfied, it can be said that the above formula (2) is also satisfied, and the shape of the opening end of at least one main surface (that is, the main surface on the side mounted on the base) can be changed. , The shape can be controlled to have no convex portion.
Further, more preferably, the following equations (1') and (2') may be satisfied.

35 ≦ | (MG2 / WG1) × 100 | ≦ 150 ・ ・ (1')
35 ≦ | (MG2'/ WG1') × 100 | ≦ 150 ・ ・ (2')
With such a configuration, it is possible to have a structure having no convex portion at the open end of both main surfaces (S1 and S2).

Further, the main surface (for example, S2) facing the main surface (for example, S1) on the side mounted on the base is often formed with a pad for electrical connection with the element, and is preferably flat. .. From such a viewpoint, it can be said that a form satisfying the above formulas (1') and (2') is more preferable.

[2. Other embodiments]
It is needless to say that the present invention is not limited to the above-described embodiment or the like, and various forms can be adopted as long as it belongs to the technical scope of the present invention.

(1) For example, in the above-described embodiment, the case where one first metal layer and one second metal layer are provided is taken as an example, but the first metal layer and the second metal layer are 1 or Multiple layers can be adopted.
(2) It is desirable that the first metal layer is entirely composed of tungsten, and similarly, it is desirable that the second metal layer is entirely composed of molybdenum, but in the first metal layer and the second metal layer, Some other components (such as glass) may be contained.

(3) In the above embodiment, the case where the first metal layer and the second metal layer are provided in an annular shape has been mentioned, but the first metal layer and the second metal layer may not be provided in an annular shape. For example, in a plan view, a shape such as a rectangle can be adopted, or a complicated plan shape may be adopted.

(4) As the ceramic constituting the ceramic substrate, for example, aluminum nitride, zirconia, mullite and the like can be adopted in addition to alumina.
(5) The function of one component in each of the above embodiments may be shared by a plurality of components, or the function of the plurality of components may be exerted by one component. Further, a part of the configuration of each of the above embodiments may be omitted. In addition, at least a part of the configuration of each of the above embodiments may be added or replaced with respect to the configuration of another embodiment. It should be noted that all aspects included in the technical idea specified from the wording described in the claims are embodiments of the present invention.

1 ... Ceramic wiring board 3 ... Ceramic board 5 ... Through hole 15 ... First metal layer 17 ... Second metal layer 21 ... Ceramic green sheet 23 ... First metal pattern 25 ... Second metal pattern 27 ... Laminated body 29 ... Opening

Claims (4)

A ceramic substrate that has a through hole that penetrates in the thickness direction and is mainly composed of ceramic,
A plurality of metal layers arranged inside the ceramic substrate,
In a ceramic wiring board equipped with
As the metal layer, one or more first metal layers made of tungsten and one or more second metal layers made of molybdenum are included, and the first metal layer and the second metal layer are It is arranged so that at least a part of it overlaps when viewed from the thickness direction.
Moreover, the second metal layer is arranged only on one surface side of the ceramic wiring board in the thickness direction from the center of the ceramic wiring board in the thickness direction.
The total WG1 obtained by summing the product of the product of the distance T1 from the center of the ceramic wiring board in the thickness direction to the first metal layer and the volume of the first metal layer for all the first metal layers.
The product of the product of the distance T2 from the center of the ceramic wiring substrate in the thickness direction to the second metal layer and the volume of the second metal layer is the total MG2 for all the second metal layers.
However, a ceramic wiring board satisfying the following formula (1).
| (MG2 / WG1) x 100 | ≤200 ... (1)
(However, for distances T1 and T2, one direction from the center is positive and the other direction is negative.) The ceramic is alumina.
The ceramic wiring board according to claim 1. The first metal layer and the second metal layer are arranged on a plane perpendicular to the thickness direction at different positions in the thickness direction of the ceramic substrate.
The ceramic wiring board according to claim 1 or 2. The method for manufacturing a ceramic wiring board according to any one of claims 1 to 3.
The first step of applying the tungsten paste containing tungsten to the surface of the first ceramic green sheet to form a first metal pattern to be a first metal layer, and
A second step of applying the molybdenum paste containing molybdenum to the surface of the second ceramic green sheet to form a second metal pattern to be a second metal layer.
One or more of the first ceramic green sheets and one or more of the second ceramic green sheets are laminated to form an opening serving as a through hole containing a first metal pattern and a second metal pattern inside. The third step of producing the laminated body to have and
The fourth step of firing the laminate to produce a ceramic wiring board, and
With
When the laminated body is produced in the first to third steps,
The total WG1'of the product of the product of the distance T1'from the center of the laminated body in the thickness direction, which is the laminating direction, to the volume of the first metal pattern and the volume of the first metal pattern for all the first metal patterns. When,
The product of the distance T2'from the center of the laminated body in the thickness direction to the second metal pattern and the volume of the second metal pattern is the total MG2'for all the second metal patterns.
However, a method for manufacturing a ceramic wiring board that satisfies the following formula (2).
| (MG2'/ WG1') x 100 | ≤200 ... (2)
(However, for the distances T1'and T2', one direction from the center is positive and the other direction is negative.)

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