JP2014220438A - Multilayer ceramic substrate and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer ceramic substrate having a plurality of continuous via conductors penetrating a plurality of ceramic layers coaxially in the thickness direction, and insulating only the continuous via conductors not requiring conduction, where the dimensions and shape of the substrate body are accurate, and to provide a manufacturing method capable of obtaining a multilayer ceramic substrate surely at a relatively low cost.SOLUTION: A multilayer ceramic substrate 1a includes a substrate body 2a laminating a plurality of ceramic layers 3-5, and a plurality of continuous via conductors 12 penetrating a plurality of adjacent ceramic layers 3-5 coaxially in the thickness direction in the substrate body 2a. At least one of the continuous via conductors 12 is insulated by a ceramic-based insulation layer 20 located between a plurality of ceramic layers 4, 5 adjacent in the continuous via conductors 12. Such an insulation layer 20 is located in a gap 13s within the wiring layer 13 formed between adjacent ceramic layers 4, 5, or in a gap 13g between a plurality of wiring layers 13.

Description

  The present invention relates to a multilayer ceramic substrate having a plurality of continuous via conductors that pass through a plurality of ceramic layers coaxially along the thickness direction and a method for manufacturing the same.

For example, in a manufacturing process of a ceramic substrate having a via conductor that penetrates a ceramic layer, a plurality of wires disposed in a dedicated mold are disposed on a green sheet in which a wiring layer is previously formed on at least one of the front surface and the back surface. A plurality of via holes are drilled at required positions by punches. By the way, if a dedicated mold is prepared each time a ceramic substrate including via conductors with different patterns is manufactured, there is a problem that the mold cost and the cost of the obtained ceramic substrate increase.
In order to solve the above-mentioned problems and to make the via hole drilling die as common as possible, to reduce costs, and to facilitate maintenance management, a plurality of via holes are formed in the green sheet by a plurality of punches in the common die. After filling and filling the conductor paste in each via hole, select the conductor paste for each position where conduction between the upper and lower wiring layers is unnecessary, and expose the exposed surfaces at the upper and lower ends of the conductor paste. There has been proposed a method of manufacturing a multilayer wiring ceramic substrate that is coated with an insulating layer formed on the front surface or the back surface of a green sheet so as to be in a non-conductive state (see, for example, Patent Document 1).

In the manufacturing method of the multilayer wiring ceramic substrate, the conductive paste at a position where conduction between the upper and lower wiring layers is not required on at least one of the front and back surfaces of the green sheet having the conductive paste filled in the plurality of via holes. The insulating layer is formed on almost the entire front surface or back surface of the green sheet so as to cover the exposed surface and expose the end surface of the conductive paste for each position where conduction is required.
However, as described above, when the insulating layer is formed over almost the entire surface of the green sheet, the thickness of the entire multilayer wiring ceramic substrate is increased, which is contrary to the demand for thinning or miniaturization, and the conduction is necessary. Forming the porous insulating layer that opens at every exposed end surface of the conductive paste on almost the entire surface of the green sheet has the problem that the manufacturing process becomes complicated.

JP 2006-291463 A (pages 1 to 6, FIGS. 1 to 6)

  The present invention solves the problems described in the background art, has a plurality of continuous via conductors that pass through a plurality of ceramic layers coaxially along the thickness direction, and insulates only the continuous via conductors that do not require conduction. It is another object of the present invention to provide a multilayer ceramic substrate in which the dimensions and shape of the substrate body are accurate, and a manufacturing method capable of reliably obtaining the multilayer ceramic substrate at a relatively low cost.

Means for Solving the Problems and Effects of the Invention

In order to solve the above-mentioned problem, the present invention forms an insulating layer in the vicinity of the connecting portion between unit via conductors that penetrate through the ceramic layers adjacent in the thickness direction and in a gap in the wiring layer located between the ceramic layers. , It was conceived.
That is, the multilayer ceramic substrate of the present invention (Claim 1) includes a substrate main body on which a plurality of ceramic layers are laminated, and a plurality of adjacent ceramic layers penetrating coaxially along the thickness direction in the substrate main body. A plurality of continuous via conductors, wherein at least one of the continuous via conductors is insulated by a ceramic insulating layer located between the plurality of adjacent ceramic layers in the continuous via conductor. In addition, the insulating layer is characterized in that it is located in a gap in a wiring layer formed between adjacent ceramic layers or in a gap between a plurality of wiring layers.

According to this, among the plurality of continuous via conductors that pass through the plurality of ceramic layers coaxially, a continuous via conductor that does not require conduction is a gap in the wiring layer through which the via conductor passes or a plurality of adjacent via conductors ( (2 or more) is electrically insulated by a ceramic insulating layer formed in a gap between wiring layers. Moreover, the insulating layer is formed in a gap located inside the wiring layer disposed between two ceramic layers adjacent in the thickness direction, or a gap between a plurality of wiring layers adjacent in the same ceramic layer. Yes. Therefore, a plurality of continuous via conductors are formed along the thickness direction of the plurality of ceramic layers by a common mold, and the continuous via conductors that do not require conduction among them are insulated by the insulating layer and the insulating layers. Since the layer is formed in any one of the gaps, it is difficult for adverse effects such as dents to occur on the front and back surfaces of the substrate body.
Therefore, a plurality of continuous via conductors that pass through a plurality of ceramic layers coaxially along the thickness direction are insulated, and only the continuous via conductors that do not require conduction are insulated, and the size and shape of the substrate body are accurate. It is a multilayer ceramic substrate.

The ceramic includes, for example, glass ceramics which are a kind of low-temperature fired ceramics, in addition to high-temperature fired ceramics such as alumina, mullite, and aluminum nitride.
In addition, the insulating layer is the same ceramic as the ceramic, the same kind of ceramic having the same first component as the ceramic, or a different kind of ceramic having a different first component, and contains these ceramics as a main component. Also included.
Furthermore, the continuous via conductor penetrates a plurality of ceramic layers coaxially, even if the axis centers of individual unit via conductors are misaligned between adjacent ceramic layers, they can contact each other and be electrically conductive. It points to something.
The continuous via conductor, the unit via conductor, and the wiring layer are made of, for example, W, Mo, Cu, Ag, or the like, or an alloy based on any of these (first component).

Furthermore, the continuous via conductor includes a cylindrical continuous through-hole conductor formed along the inner wall surface of the plurality of through-holes formed coaxially in the plurality of ceramic layers, and the continuous through-hole conductor includes: A plurality of unit through-hole conductors having the same or equivalent outer diameter and inner diameter are connected coaxially.
In addition, the gap located in the wiring layer exhibits a circle, an oval, an ellipse, a regular polygon that is greater than or equal to a square, or a deformed polygon in plan view.
Further, the plurality of wiring layers are positioned between the ceramic layers between a plurality of (two) wiring layers that are located adjacent to each other and located adjacent to each other in a plan view. This is a region exhibiting a strip shape or a different shape.
Further, since the ceramic layer and the insulating layer are made of ceramics having different compositions, the density of the ceramic layer and the insulating layer are different from each other even when the ceramic layer and the insulating layer are made of the same ceramic. It is possible.
In addition, the insulating layer has at least twice the diameter of the continuous via conductor to be insulated in a plan view, preferably three times the diameter, the short diameter, or the length of one side.

In the present invention, the substrate body has a cavity that opens to the center of the surface of the substrate body, and the plurality of adjacent ceramic layers form the bottom surface and side surfaces of the cavity. A part of the peripheral portion of the insulating layer is flush with a side surface of the cavity, or extends to a bottom side of the cavity and is exposed in the cavity. 2) is also included.
According to this, between the two ceramic layers adjacent to each other in the thickness direction and forming the bottom surface and the side surface of the cavity, the gap is located between the plurality of adjacent wiring layers, and at least the 2 The ceramic insulating layer is formed in the middle of the continuous via conductor that passes through the ceramic layer coaxially in the thickness direction. Moreover, the peripheral portion of the insulating layer on the cavity side, or a part of the peripheral portion, is flush with the side surface of the cavity (almost flush), or extends to the bottom surface side of the cavity and It is exposed in the cavity. Therefore, among the plurality of continuous via conductors, the continuous via conductors that do not need to be electrically conductive can be insulated, and the green sheet on the upper layer side surrounding the cavity is inclined toward the cavity side in the laminating process and the subsequent crimping process at the time of manufacture. Since the situation of falling is suppressed, the multilayer ceramic substrate has a substrate body including a cavity having a required shape and size.
In addition, the said flat shape includes that a part of the peripheral portion is located in a range of 100 μm or less (for example, about several tens of μm) on the back side of the side surface of the cavity.

  On the other hand, a method for manufacturing a multilayer ceramic substrate according to the present invention (Claim 3) includes a substrate body in which a plurality of ceramic layers are laminated, and a plurality of adjacent ceramic layers in the substrate body coaxially along the thickness direction. A method of manufacturing a multilayer ceramic substrate having a plurality of continuous via conductors penetrating therethrough, the step of forming a plurality of via holes in a plurality of ceramic green sheets, and filling a via paste for each green sheet with a conductive paste A step of forming an unfired unit via conductor, and printing a conductive paste on at least one of the front and back surfaces of the green sheet, and a non-fired wiring layer having a gap inside, or a plurality of unfired adjacent layers Forming the wiring layer and at least one of the front and back surfaces of the at least one green sheet. Disposing a ceramic insulating paste around the position where the end face of the conductor is exposed to form a green insulating layer, and a plurality of the green sheets, and the unit via conductor for each green sheet Laminating so as to be concentrically continuous along a direction, and in the step of forming the insulating layer, the unfired insulating layer is a gap in the wiring layer or between the plurality of wiring layers. It is formed in a gap between them.

According to this, among the plurality of unit via conductors formed so as to pass through a plurality of green sheets coaxially by a common mold, the plurality of unit via conductors that do not require conduction are the plurality of unit via conductors. It is electrically insulated by a ceramic insulating layer formed in a gap in the wiring layer through which the via conductor penetrates or in a gap between a plurality of (two or more) adjacent wiring layers. Moreover, the insulating layer is formed in a gap located inside the wiring layer disposed between two green sheets adjacent in the thickness direction, or a gap between a plurality of adjacent wiring layers between the same green sheets. Is done. Therefore, a plurality of continuous via conductors obtained after firing are formed along the thickness direction of the plurality of ceramic layers after lamination, and among these, the continuous via conductors that do not require conduction are insulated by the insulating layer. At the same time, since the insulating layer is formed in any one of the gaps, it is possible to eliminate the occurrence of dents on the front and back surfaces of the substrate body after lamination and firing.
Accordingly, it is possible to reliably manufacture a multilayer ceramic substrate with a precise size and shape of the substrate body including a plurality of continuous vias at a relatively low cost.

The ceramic green sheet is obtained by molding a ceramic slurry in which a binder resin or a solvent is mixed with the ceramic powder into a sheet shape.
In addition, after the laminating step, a step of firing a laminated body of a plurality of laminated ceramic green sheets simultaneously with the continuous via conductor, wiring layer, etc., and then plating on the surface of the front and back terminals exposed to the outside And a plating step for coating the layer.
Further, the manufacturing method includes a plurality of green sheets each including a product region having a plurality of substrate regions adjacent to each other in the vertical and horizontal directions in plan view and an ear portion located on the outer peripheral side thereof. Forms are also included.

Further, in the present invention, the plurality of green sheets constitute a bottom surface of a cavity that opens to the center side of the surface of the substrate body and a side surface of the cavity, and are formed between the plurality of green sheets. In the laminating step, a part of the periphery of the unfired insulating layer is flush with the side surface of the cavity, or extends to the bottom surface of the cavity and is exposed in the cavity. And a method of manufacturing a multilayer ceramic substrate (claim 4).
According to this, between the two green sheets adjacent to each other in the thickness direction that form the bottom surface and the side surface of the cavity, the gap is located between the plurality of wiring layers adjacent between the green sheets, and at least The ceramic insulating layer is formed in the middle of the continuous via conductor that passes through the two green sheets coaxially in the thickness direction. In addition, the peripheral portion of the insulating layer on the cavity side or a part of the peripheral portion is flush with the side surface of the cavity, or extends to the bottom surface side of the cavity and is exposed in the cavity. . Therefore, among the plurality of continuous via conductors, continuous via conductors that do not need to be electrically conductive can be insulated, and in the stacking step and the subsequent crimping step, the upper layer side green sheet surrounding the cavity is inclined toward the cavity side (falling down) Therefore, a multilayer ceramic substrate having a substrate body including a cavity having a required shape and size can be reliably manufactured at a relatively low cost.

1 is a vertical sectional view showing a first multilayer ceramic substrate according to the present invention. (A) is a partial cross-sectional view taken along the line AA in FIG. 1, (B) is a partial cross-sectional view taken along the line BB in FIG. 1, and (C) is (B Sectional drawing which shows the deformation | transformation form of). The schematic sectional drawing which shows one manufacturing process for obtaining a 1st multilayer ceramic substrate. Sectional drawing which shows the outline of the manufacturing process following FIG. Sectional drawing which shows the outline of the manufacturing process following FIG. Sectional drawing which shows the outline of the manufacturing process following FIG. Sectional drawing which shows the outline of the manufacturing process following FIG. Sectional drawing which shows the outline of the manufacturing process following FIG. FIG. 3 is a vertical sectional view showing a second multilayer ceramic substrate according to the present invention. FIG. 10 is a horizontal sectional view taken along the line XX in FIG. 9. The schematic sectional drawing which shows one manufacturing process for obtaining a 2nd multilayer ceramic substrate. Sectional drawing which shows the outline of the manufacturing process following FIG. Sectional drawing which shows the outline of the manufacturing process following FIG.

Hereinafter, modes for carrying out the present invention will be described.
FIG. 1 is a vertical sectional view showing a first multilayer ceramic substrate 1a according to the present invention, FIG. 2A is a partial sectional view taken along the line AA in FIG. 1, and FIG. FIG. 2 is a partial cross-sectional view taken along the line B-B in FIG. 1, and FIG. 2C is a modified form of (B).
As shown in FIG. 1, the first multilayer ceramic substrate 1a includes a substrate body 2a in which a plurality of ceramic layers 3 to 5 are laminated and has a front surface 6 and a back surface 7, and a front surface 6 and a back surface 7 of the substrate body 2a. There are provided a plurality of continuous via conductors 12 that pass coaxially there between, and a plurality of wiring layers 13 having a predetermined pattern formed between the ceramic layers 4 and 5. Further, a front surface terminal 14 is formed on the front surface 6 of the substrate main body 2a and is individually connected to the upper end portion of each continuous via conductor 12. The back terminals 15 are individually connected to each other.
The ceramic layers 3 to 5 are made of, for example, a ceramic mainly composed of alumina. The continuous via conductor 12, the wiring layer 13, the front and back terminals 14 and 15 are made of, for example, W, Mo, Cu, or Ag.

As shown in FIG. 1, the five (plural) continuous via conductors 12 are formed in the substrate body 2 a so as to penetrate the ceramic layers 3 to 5 coaxially along the thickness direction. Among these, the two continuous via conductors 12 positioned at the left and right ends in FIG. 1 are connected to the wiring layer 13 formed between the ceramic layers 4 and 5. Moreover, the continuous via conductor 12 located in the center in FIG. 1 penetrates the ceramic layers 3 to 5 constituting the substrate body 2a independently and linearly.
Further, the two continuous via conductors 12 positioned every second from the left and right in FIG. 1 are unnecessary for the first multilayer ceramic substrate 1a. Therefore, the two continuous via conductors 12 are insulated by a ceramic insulating layer 20 formed at each position so as to intersect between the ceramic layers 4 and 5. The insulating layer 20 is also made of a ceramic mainly composed of alumina similar to the ceramic layers 3 to 5.

That is, as shown in FIG. 2A, which is a partial sectional view taken along the line AA in FIG. 1, the continuous via conductor 12 located second from the left in FIG. The plan view opened in the wiring layer 13 located between the two is insulated by the insulating layer 20 formed in the circular gap 13s. The diameter of the insulating layer 20 is about three times the diameter of the continuous via conductor 12.
On the other hand, as shown in FIG. 2B, which is a partial cross-sectional view taken along the line BB in FIG. 1, the continuous via conductor 12 located second from the right in FIG. 5 is insulated by an insulating layer 20 formed in a gap 13g between two adjacent wiring layers 13. As shown in the figure, the gap 13g includes a circular portion that is approximately three times the diameter of the continuous via conductor 12 and two adjacent wiring layers 13 in the vicinity of the upper and lower end faces of the insulated continuous via conductor 12. In the meantime, it consists of a strip-shaped portion having a minimum width necessary for insulation between the wiring layers 13.
As shown in FIG. 2C, the insulating layer 20 located in the gap 13g is located between the adjacent two wiring layers 13 in the gap 13g and in the vicinity of the continuous via conductor 12 to be insulated. You may form only in the part of circular nourishment located in.

According to the first multilayer ceramic substrate 1a as described above, among the plurality of continuous via conductors 12 that pass through the plurality of ceramic layers 3 to 5 coaxially, the continuous via conductor 12 that does not require conduction is the via. The conductor 12 is insulated by the insulating layer 20 formed in the gap 13s in the wiring layer 13 through which the conductor 12 passes or in the gap 13g between two adjacent wiring layers 13. In addition, the insulating layer 20 includes the gap 13 s located in the wiring layer 13 disposed between the two ceramic layers 4 and 5 adjacent in the thickness direction, or two adjacent adjacent ceramic layers 4 and 5. A gap 13g between the wiring layers 13 is formed. Therefore, a plurality of continuous via conductors 12 are formed along the thickness direction of the plurality of ceramic layers 3 to 5 by a common mold, and the continuous via conductors 12 that do not require conduction are insulated by the insulating layer 20. In addition, since the insulating layer 20 is formed in the gaps 13s and 13g, adverse effects such as dents are unlikely to occur on the front surface 6 and the back surface 7 of the substrate body 2a.
Therefore, the plurality of continuous via conductors 12 that pass through the plurality of ceramic layers 3 to 5 coaxially along the thickness direction are insulated, and only the continuous via conductor 12 that does not need to be electrically conductive is insulated. The multilayer ceramic substrate 1a is accurate in shape.

Below, the manufacturing method of the said multilayer ceramic substrate 1a is demonstrated.
By mixing an appropriate amount of alumina powder, binder resin, solvent, and the like in advance, the obtained ceramic slurry is formed into a sheet shape by the doctor blade method, thereby obtaining three green sheets g3 to g5 as shown in FIG. Prepared.
Next, as shown in FIG. 4, a plurality of via holes 12h having a common inner diameter are seen in a plan view by a punching die having a plurality of punches (not shown) at predetermined positions in the green sheets g3 to g5. They were formed at approximately equal intervals.
Next, each of the via holes 12h in the green sheets g3 to g5 is filled with a conductive paste containing W or Mo powder, thereby forming a plurality of unfired unit via conductors 12u as shown in FIG. . As shown in the drawing, the plurality of unit via conductors 12u are formed at positions that are coaxial with each other in the thickness direction of the green sheets g3 to g5.

Furthermore, the same conductive paste as described above is screen-printed on the surface of the green sheet g5 located at the lowermost layer in FIG. Wiring layer 13 and two unfired and two wiring layers 13 adjacent to each other with a gap 13g interposed therebetween. As shown in FIG. 5, the upper end surface of one unit via conductor 12u formed in the green sheet g5 was exposed at the center of the gap 13s. In addition, the upper end surface of another unit via conductor 12u was exposed at the center of the circular portion in plan view in the gap 13g.
Next, as shown in FIG. 6, a screen having a predetermined pattern is formed in the gap 13s located in the wiring layer 13 and in the gap 13g sandwiched between two adjacent wiring layers 13 (see FIG. 6). An unfired insulating layer 20 was formed by filling an insulating paste 20p containing alumina (ceramic) powder using a squeegee 29 and a squeegee 29, respectively.

Next, the green sheets g3 and g4 on which the plurality of unit via conductors 12u are formed, and the green sheet 5 on which the same unit via conductors 12u, the insulating layer 20, and the plurality of wiring layers 13 are formed as green sheets The unit via conductors 12u for each of g3 to g5 were laminated so as to be in contact with each other along the axial direction, and further pressed.
As a result, as shown in FIG. 7, an unfired substrate body 2a made of green sheets g3 to g5 and three unit vias that are located in the center in FIG. 7 and pass through the green sheets g3 to g5 coaxially. An unfired laminated body 24 including the conductor 12u and the three wiring layers 13 connected to the upper and lower unit via conductors 12u located between the green sheets g4 and g5 and located at the left end or the right end in FIG. 7 is obtained. It was. In the laminate 24, the upper and lower unit via conductors 12u located second from the left in FIG. 7 are insulated from the insulating layer 20 located in the gap 13s in the left wiring layer 13 in FIG. Further, the upper and lower unit via conductors 12u located second from the right in FIG. 7 are insulated from the insulating layer 20 located in the gap 13g between the two adjacent wiring layers 13 on the right side in FIG.

Furthermore, as shown in FIG. 8, the same conductive paste as described above is screen-printed on each unit via conductor 12u exposed on the surface 6 of the substrate body 2a in the laminate 24, and a plurality of unfired plural pastes The front surface terminals 14 are formed, and the same conductive paste as described above is screen-printed on each unit via conductor 12u exposed on the back surface 7 of the substrate body 2a to form a plurality of unfired back surface terminals 15. did.
Then, after degreasing and firing the laminate 24, it is sequentially immersed in an electrolytic Ni plating solution and an electrolytic Au plating solution, and on the surfaces of the front surface terminals 14 and the rear surface terminals 15 exposed to the outside of the substrate body 2a, A plating layer (not shown) composed of a Ni plating film on the base side and an Au plating film on the surface layer side was coated. As a result, the first multilayer ceramic substrate 1a shown in FIGS. 1, 2A and 2B was obtained.
In the firing step, the green sheets g3 to g5 are fired into the ceramic layers 3 to 5, and the plurality of unit via conductors 12u that have been in contact with each other in a coaxial manner become a plurality of continuous via conductors 12, and part of them Insulated by the fired insulating layer 22.
Moreover, you may perform the manufacturing method of the above multilayer ceramic substrates 1a with the form of many pieces.

According to the manufacturing method of the first multilayer ceramic substrate 1a as described above, among the plurality of unit via conductors 12u formed so as to penetrate the plurality of green sheets g3 to g5 coaxially by a common mold, The plurality of unit via conductors 12u that do not require conduction are formed by the insulating layer 20 formed in the gap 13s in the wiring layer 13 through which the plurality of via conductors 12u pass or the gap 13g between two adjacent wiring layers 13. Electrically isolated. Moreover, the insulating layer 20 includes a gap 13s located in the wiring layer 13 disposed between the green sheets g4 and g5 adjacent in the thickness direction, and between the two wiring layers 13 adjacent between the green sheets g4 and g5. Formed in a gap 13g. Therefore, a plurality of continuous via conductors 12 that are coaxial are formed along the thickness direction of the plurality of green sheets g3 to g5 after lamination, and among these, the continuous via conductor 12 that does not require conduction is the insulating layer. 20 and the insulating layer 20 is formed in one of the gaps 13s and 13g, so that there is no occurrence of dents on the front surface 6 and the rear surface 7 of the substrate body 2a after lamination and after firing. I was able to.
Therefore, the multilayer ceramic substrate 1a in which the size and shape of the substrate body 2a including the plurality of continuous via conductors 12 are accurate can be reliably manufactured at a relatively low cost.

FIG. 9 is a vertical sectional view showing a second multilayer ceramic substrate 1b according to the present invention, and FIG. 10 is a horizontal sectional view taken along line XX in FIG.
As shown in FIGS. 9 and 10, the multilayer ceramic substrate 1b includes a substrate body 2b having a front surface 6b and a back surface 7 formed by laminating a plurality of ceramic layers 8 to 10 similar to the above, and a surface of the substrate body 2b. The cavity 16 opened to the center side in 6b, and a plurality of continuous via conductors 12 that coaxially penetrate the ceramic layers 8 to 10 surrounding the cavity 16 in the thickness direction. The upper and middle ceramic layers 8 and 9 have a rectangular frame shape in plan view in order to provide the cavity 16, and the cavity 16 is a bottom surface that is substantially square in plan view and is a part of the surface of the ceramic layer 10. 17 and four side surfaces 18 erected vertically from the four sides of the bottom surface 17. A front surface terminal 14 provided on the front surface 6 b of the substrate body 2 b and a back surface terminal 15 provided on the back surface 7 are individually connected to the upper and lower ends of each continuous via conductor 12.

Also, as shown in FIGS. 9 and 10, a plurality of via conductors 21 penetrate between the bottom surface 17 of the cavity 16 and the back surface 7 of the substrate body 2 b, and are the upper ends of the via conductors 21. The same number of internal terminals 19 are formed on the bottom surface 17 of the cavity 16. On the internal terminal 19, an electronic component (not shown) to be mounted in the cavity 16 later is mounted. A back surface terminal 15 provided on the back surface 7 of the substrate body 2b is individually connected to the lower end of each via conductor 21.
Further, as shown in FIGS. 9 and 10, a plurality of wiring layers 23 having a square shape in plan view are formed apart from each other between the middle ceramic layer 9 and the lower ceramic layer 10. A plurality of insulating layers 22 similar to those described above are individually formed for each gap 23g having a square shape in plan view located between the layers 23.

In FIG. 10, circular gaps 23s are formed in the wiring layers 23 located at the four corners, and the insulating layer 22 disposed in the gaps 23s insulates the continuous via conductors 12 in contact with the central part of the gaps 23s. ing. In FIG. 10, continuous via conductors 12 are individually connected to the upper and lower surfaces of a plurality of wiring layers 23 located on the four sides.
On the other hand, in FIG. 10, a rectangular insulating layer 22 is formed for each gap 23g between the plurality of wiring layers 23 located on the four sides, and the upper and lower continuous via conductors 12 are insulated by the insulating layer 22. . The peripheral portion 22a on the cavity 16 side in the insulating layer 22 is flush with the side surface 18 of the cavity 16 or extends to the bottom surface 17 side of the cavity 16 as shown in FIGS. The cavity 16 is exposed.
Note that a part of the peripheral portion 22a may be a part of the side on the cavity 16 side. Further, the peripheral portion 22a may be flush (substantially flush) positioned slightly below the side surface 18 of the cavity 16 within the range of 100 μm or less.

According to the second multilayer ceramic substrate 1b as described above, the bottom surface 17 and the side surface 18 of the cavity 16 are formed and between the adjacent ceramic layers 9 and 10 in the thickness direction, and the ceramic layers 9 and 10 are formed. The insulating layer is located in the middle of any of the plurality of continuous via conductors 12 that are located in the gaps 23g between the plurality of adjacent wiring layers 23 and pass through the plurality of ceramic layers 8 to 10 coaxially in the thickness direction. 22 is formed. Moreover, the peripheral portion 22a on the cavity 16 side in the insulating layer 22 or a part of the peripheral portion 22a is flush with the side surface 18 of the cavity 16 or extends to the bottom surface 17 side of the cavity 16 and The cavity 16 is exposed. In addition, the insulating layer 22 provided in the gap 23 s in the wiring layer 23 does not cause a dent in the surface 6 b of the substrate body 2 b surrounding the opening of the cavity 16.
Therefore, among the plurality of continuous via conductors 12, the continuous via conductor 12 that does not need to be electrically conductive can be insulated, and the upper green sheet surrounding the cavity 16 tilts toward the cavity and falls down in the lamination and crimping process at the time of manufacture. Since the situation is suppressed, the multilayer ceramic substrate 1b has the substrate body 2b including the cavity 16 having a required shape and size.

Hereinafter, a method for manufacturing the multilayer ceramic substrate 1b will be described.
Three green sheets g8 to g10 were prepared in advance by the same method as described above. Among these, punching with a punch having a square cross section and a die having a punch hole having a shape similar to that of the cross section was performed on the central portion of the green sheets g8 and g9 on the upper layer side. As a result, as shown in FIG. 11, in addition to the flat green sheet 10 on the lower layer side, green sheets g8 and g9 having square through holes 18h in plan view were obtained.
Next, as shown on the right side in FIG. 11, a plurality of via holes 12h were formed at predetermined positions in the green sheets g8 to g10 by a punching die having a plurality of punches similar to the above. Next, as shown on the left side in FIG. 11, each of the via holes 12h was filled with the same conductive paste as described above to form unfired unit via conductors 12u individually.

Furthermore, after the plurality of wiring layers 23 are formed by screen printing the same conductive paste as described above along the periphery of the surface of the green sheet g10 on the lower layer side, as shown in FIG. For each gap 23g between the layers 23, an unfired insulating layer 22 made of the same insulating paste was printed in the same manner as described above. At this time, the width w2 between the center side and the peripheral side of the green sheet g10 in the insulating layer 22 was formed larger than the width w1 of the green sheets g8 and g9 on the middle and upper layers.
Next, the green sheets g8 and g9 on which the plurality of unit via conductors 12u are formed, and the green sheet 10 on which the same unit via conductors 12u, the insulating layer 22, and the plurality of wiring layers 23 are formed are green. The unit via conductors 12u for each of the sheets g8 to g10 were laminated so as to be in contact with each other along the axial direction, and further pressure-bonded.

As a result, as shown in FIG. 13, green sheets g8 to 10 are laminated, an unfired substrate body 2b having a front surface 6b and a back surface 7 and a cavity 16 opened to the front surface 6b, A plurality of via conductors 21 penetrating between the bottom surface 17 and the back surface 7 of the substrate body 2b; a plurality of unfired and plural sets of unit via conductors 12u coaxially penetrating the peripheral portion of the substrate body 2b; Of these, an unfired laminated body 26 including unfired insulating layers 22 formed between the unit via conductors 12u to be insulated and between the green sheets g9 and g10 was obtained.
In the multilayer body 26, the unit via conductors 12 u are coaxially connected to the upper and lower surfaces of a part of the wiring layers 23 among the plurality of wiring layers 23. The upper and lower unit via conductors 12 u that are in coaxial contact with the upper and lower surfaces of the central portion of the insulating layer 22 are insulated by the unfired insulating layer 22 formed in the gap 23 s located in the inner space 23.

Moreover, since the width w2 of the insulating layer 22 is set in advance larger than the width w1 of the upper and middle green sheets g8 and g9, the green sheets g8 and g9 surrounding the cavity 16 It was also possible to reliably prevent the so-called “falling” phenomenon that leans toward the cavity 16 side.
Further, as shown in FIG. 13, the internal terminal 19 and the back terminal 15 are individually connected to the upper and lower ends of the via conductor 21, and each of the upper and lower ends of the plurality of unit via conductors 12 u that are coaxial, The front surface terminal 14 and the back surface terminal 15 were individually connected.
And after degreasing and baking the said laminated body 26, each surface terminal 14, each back surface terminal 15 exposed to the exterior of the said board | substrate main body 2b, each back surface terminal, and each inside are immersed in electrolytic Ni plating liquid and electrolytic Au plating liquid sequentially. The surface of the terminal 19 was covered with a plating layer (not shown) composed of a Ni plating film on the base side and an Au plating film on the surface layer side. As a result, the first multilayer ceramic substrate 1b shown in FIGS. 9 and 10 was obtained.

Even during the firing, since the width w2 of the insulating layer 22 was previously set larger than the width w1 of the upper and middle green sheets g8 and g9, the insulating layer 22 on the cavity 16 side in the fired insulating layer 22 was previously set. The peripheral portion 22 a extends to the bottom surface 17 side of the cavity 16 or is at least flush with the side surface 18 of the cavity 16.
Further, in the firing step, the green sheets g8 to g10 become the ceramic layers 8 to 10, and the plurality of unit via conductors 12u that are in contact with each other coaxially become a plurality of continuous via conductors 12, and part of them Insulated by the fired insulating layer 22.
Furthermore, the manufacturing method of the multilayer ceramic substrate 1b as described above may be performed in a multi-cavity form.

According to the manufacturing method of the second multilayer ceramic substrate 1b as described above, a plurality of wiring layers which form the bottom surface 17 and the side surface 18 of the cavity 16 and are adjacent between the green sheets g9 and g10 adjacent in the thickness direction. The insulating layer 22 is formed in the middle of a plurality of unit via conductors 12u that are located in the gap 23g between the 23 and pass through the green sheets g8 to g10 coaxially in the thickness direction. Moreover, the peripheral portion 22a on the cavity 16 side in the insulating layer 22 or a part of the peripheral portion 22a is flush with the side surface 18 of the cavity 16 or extends to the bottom surface 17 side of the cavity 16 and It was exposed in the cavity 16. In addition, the insulating layer 22 provided in the gap 23 s in the wiring layer 23 did not cause dents on the surface 6 b of the substrate body 2 b surrounding the opening of the cavity 16.
Therefore, among the plurality of continuous via conductors 12, the continuous via conductor 12 which does not need to be electrically conductive can be insulated, and the upper side green sheets g8 and g9 surrounding the cavity 16 can be formed in the cavity in the laminating process, the crimping process, and the firing process. Since the situation of tilting toward the side 16 could be suppressed, the multilayer ceramic substrate 1b having the substrate body 2b including the cavity 16 having the required shape and size could be reliably manufactured at a relatively low cost.

The present invention is not limited to the embodiments described above.
For example, the ceramic of the ceramic layer is not limited to the alumina, but may be a high-temperature fired ceramic such as mullite or aluminum nitride, or a low-temperature fired ceramic such as glass-ceramic. In the latter case, Cu or Ag is applied to the conductor such as the continuous via conductor or the wiring layer.
The number of ceramic layers constituting the front substrate body is at least two, but may be four or more. Accordingly, the number of green sheets is also determined.
Further, when a plurality of non-conducting continuous via conductors are provided in the substrate body, the insulating layer that insulates these continuous via conductors is formed in the gaps that are located between the ceramic layers at different positions. Also good.
In addition, two or more cavities may be provided in one substrate body. For example, two cavities are opened on the same surface of the substrate body, or on the front and back surfaces of the same substrate body. Two cavities may be provided symmetrically in the thickness direction.

  According to the present invention, there are a plurality of continuous via conductors that pass through a plurality of ceramic layers coaxially along the thickness direction, only the continuous via conductors that do not require conduction are insulated, and the size and shape of the substrate body are It is possible to provide an accurate multilayer ceramic substrate and a manufacturing method capable of reliably obtaining the multilayer ceramic substrate at a relatively low cost.

1a, 1b ......................................................... Multilayer ceramic substrate 2a, 2b ........................... ………… Substrate body 3-5, 8-10 …………………… Ceramic layer 6b …………………………………… Surface 12 …………………………………… Continuous via conductor 12h ………………………………… Via hole 12u ………………………………… Unit via conductors 13, 23 …………………………… Wiring layers 13s, 13g, 23s, 23g… Gap 16 …………………… ……………… Cavity 17 …………………………………… Bottom 18 …………………………………… Side 20, 22 …………………… ……… Insulating layer (ceramic insulating layer)
20p …………………………………… Insulating paste 22a ………………………………… Periphery of insulating layer g3 to g5, g8 to g10 ……… Green sheet

Claims (4)

A substrate body in which a plurality of ceramic layers are laminated;
In the above substrate body, a multilayer ceramic substrate comprising a plurality of continuous via conductors coaxially passing through a plurality of adjacent ceramic layers along the thickness direction,
At least one of the continuous via conductors is insulated by a ceramic insulating layer located between the plurality of adjacent ceramic layers in the continuous via conductor, and the insulating layer is formed between the adjacent ceramic layers. Located in the gap between the wiring layers or between the plurality of wiring layers,
A multilayer ceramic substrate characterized by the above. The substrate body has a cavity opened to the center side of the surface of the substrate body, and the plurality of adjacent ceramic layers form a bottom surface and a side surface of the cavity, and a peripheral portion of the insulating layer A part of the surface is flush with the side surface of the cavity, or extends to the bottom surface side of the cavity and is exposed in the cavity.
The multilayer ceramic substrate according to claim 1, wherein: A method of manufacturing a multilayer ceramic substrate comprising: a substrate body on which a plurality of ceramic layers are laminated; and a plurality of continuous via conductors that pass through the adjacent ceramic layers coaxially along the thickness direction in the substrate body. Because
Forming a plurality of via holes in a plurality of ceramic green sheets;
Filling the via hole for each green sheet with a conductive paste to form an unfired unit via conductor;
A step of printing a conductive paste on at least one of the front and back surfaces of the green sheet to form a wiring layer that is unfired and has a gap inside, or a plurality of wiring layers that are unfired and adjacent to each other;
Forming a green insulating layer by disposing a ceramic-based insulating paste at and around the position where the end face of the unit via conductor is exposed in at least one of the front surface and the back surface of the at least one green sheet;
Laminating a plurality of the green sheets such that the unit via conductors for each green sheet are coaxially continuous along the axial direction,
In the step of forming the insulating layer, the unfired insulating layer is formed in a gap in the wiring layer or in a gap between the plurality of wiring layers.
A method for producing a multilayer ceramic substrate. The plurality of green sheets constitute a bottom surface of a cavity that opens to the center side of the surface of the substrate body, and a side surface of the cavity.
A part of the periphery of the unfired insulating layer formed between the plurality of green sheets is flush with the side surface of the cavity or extends to the bottom surface of the cavity in the stacking step. And exposed in the cavity,
The method for producing a multilayer ceramic substrate according to claim 3.

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