JP2005252079A - Multilayer ceramic board, high-frequency module, and method of manufacturing multilayer ceramic board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the need for metallizing of a conductor layer on the cavity side or a process of forming a castellation structure, and to form a conductor layer on the cavity side of a multilayer ceramic board and the board side. <P>SOLUTION: The ceramic board comprises a first ceramic board layer 6, a second ceramic board layer 7 laminated on the first ceramic board layer to form a cavity, and a third ceramic board layer 9 laminated on the second ceramic board layer 7 to form a cavity communicating with the cavity of the second ceramic board. The third layer 9 has projecting pieces 25, bent along the cavity side of the second board layer 7 on a part of the layer, and a surface conductor layer 10 is formed on the pieces 25. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a structure of a multilayer ceramic substrate in which a conductor layer is formed on a side surface of a cavity formed on the substrate or a side surface of the substrate, a manufacturing method thereof, and a high frequency circuit in which a high frequency circuit is mounted on the ceramic multilayer substrate. It is about modules.

In recent years, high-frequency modules in which high-frequency circuits such as MMICs and MICs are mounted on multilayer ceramic substrates have been used in communication devices that transmit and receive wireless signals in the millimeter wave band and microwave band. In the high frequency module, a plurality of cavities are provided in a multilayer ceramic substrate, and an MMIC is accommodated and mounted in each cavity.
At this time, the conductor thin film was metalized on the side surface of the cavity to form the GND surface, thereby suppressing interference of high-frequency signals between adjacent cavities. Further, in order to obtain the same interference suppression effect, a plurality of halved through holes having a vertically halved shape are arranged facing the wall surface of the peripheral edge of the cavity (see, for example, Patent Document 1).

JP 2002-76241 A (see FIGS. 7 and 8)

As a similar structure, a castellation structure is known in which a groove is provided on the outer peripheral side surface of a multilayer ceramic substrate, and a plurality of castellation conductors are formed in the groove. The castellation conductor is soldered to a land of an external substrate on which the multilayer ceramic substrate is mounted, and functions as a signal terminal (see, for example, Patent Document 2).
JP 2001-77507 A (see FIGS. 3 and 7)

  For halved through-holes and castellation structures, after forming a plurality of holes in a ceramic green sheet, a conductor is filled in the hole to form a VIA hole, and punching is performed so that the filled conductor is divided into two at the center. Process. Thereafter, ceramic green sheets are laminated, and the laminated substrates are simultaneously fired.

In conventional multilayer ceramic substrates, when forming half-through holes or castellation structures, stress concentration occurs due to firing shrinkage around the printed half-holes or castellation conductors, causing cracks in the substrate. There are things to do.
Furthermore, when the VIA hole is divided into two parts by punching punching after the VIA hole is printed and filled, the punching die is repeatedly punched multiple times, so that the conductor attached to the die is castellated. There has also been a problem of redeposition on the ceramic wall surface where no conductor is formed.

The cavity is formed by punching a ceramic green sheet with a punch. Innumerable irregularities are generated on the cut surface of the side surface of the cavity after processing, and the surface becomes rough. For this reason, when metallizing on the side surface of the cavity, there is a problem that the conductor adhered on a part of the surface is peeled off. Polishing the cavity side face can improve the adhesion of the metallized conductor, but in general, it is difficult to polish the side face of the cavity and requires a considerable amount of processing time.
As described above, printing filling with a plurality of VIA holes and punching by punching a half through hole or castellation conductor are difficult and require complicated processes, so the yield is not stable.

  The present invention has been made to solve such a problem, and eliminates the need for metalizing the conductor layer on the side surface of the cavity and forming a castellation structure, so that it can be applied to the cavity side surface and the substrate side surface of the multilayer ceramic substrate. The object is to form a conductor layer.

  The multilayer ceramic substrate according to the present invention includes a first ceramic substrate layer, a second ceramic substrate layer that is laminated on the first ceramic substrate layer, and a cavity is formed, and a laminate on the second ceramic substrate layer. And a protruding piece having a surface conductor layer that is bent along the side surface of the cavity of the second ceramic substrate layer is formed in a part of the layer, and the cavity communicates with the cavity of the second ceramic substrate layer. And a third ceramic substrate layer formed.

  In addition, the first ceramic substrate layer having a groove formed on the side surface and the first ceramic substrate layer are laminated, and the surface conductor layer is bent along the inner surface of the groove on the side surface of the first ceramic substrate layer. You may provide the 2nd ceramic substrate layer which has the formed protrusion piece in a part of layer.

  Further, the multilayer ceramic substrate according to the present invention has a second ceramic green sheet laminated on the first ceramic green sheet and formed with an opening hole, and an opening hole having a protruding piece on the periphery of which a surface conductor layer is formed. A laminated step of obtaining a laminated body by laminating the molded third ceramic green sheet with matching the opening holes of each other, and the protruding piece of the third ceramic green sheet in the laminated body is replaced with the second ceramic green sheet. It is formed in the order of a compression molding process for pressing and bending along the side surface of the opening hole of the sheet, and a sintering process for firing the laminate.

  According to the present invention, a metal layer is directly metallized on the side surface of the substrate or the side surface of the cavity, or the side surface of the substrate or the cavity is provided without providing a half through hole or a castellation conductor on the periphery of the side surface of the substrate or the side surface of the cavity. A conductor layer can be disposed on the side surface.

The multilayer ceramic substrate according to the present invention includes a low temperature co-fired ceramic (hereinafter referred to as LTCC) and a high temperature co-fired ceramic (hereinafter referred to as HTCC) known as alumina ceramic. Manufactured with pressure plate substrate manufacturing technology.
HTCC has a firing temperature of about 1500 ° C. or more, whereas LTCC enables firing at a low temperature of 1000 ° C. or less by adding a glass-based material or the like to the substrate material. LTCC can be fired simultaneously with a substrate material such as Ag (silver) or Cu (copper) having a low conductor resistance as a wiring material by low-temperature firing. LTCC has better high frequency characteristics (low dielectric constant, low resistance conductor) than HTCC, and can realize a high frequency band of mounted components. Further, by using Au, Ag, Ag / Pd, or Ag / Pt-based conductor paste as a conductor material, it is possible to stack fine wiring patterns with high accuracy and to realize a reduction in size of the package.
The present invention provides an effective method of forming a conductor on a cavity wall surface and a side surface of a substrate in a planar manner in a method for manufacturing a multilayer ceramic substrate. In particular, it is suitable and effective when used in the manufacture of LTCC.
Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a high-frequency module according to Embodiment 1 of the present invention. FIG. 1 (a) is a perspective view as viewed from above with the cover removed, and FIG. 1 (b) is a seal ring. FIG. 1 (c) is a cross-sectional view taken along the line AA with a cover attached to FIG. 1 (a).
2 is a diagram showing the configuration of the multilayer ceramic substrate according to the first embodiment of the present invention. FIG. 2 (a) is a perspective view as viewed from the top surface, and FIG. 2 (b) is a diagram of FIG. 2 (a). BB sectional drawing, FIG.2 (c) is a perspective view of arrow C direction, FIG.2 (d) is a perspective view of arrow D direction.

  In FIG. 1, the high-frequency module 500 includes a hermetically sealed package 1 and high-frequency circuits 5 a and 5 b such as MMIC and MIC accommodated in the package 1. For example, the high frequency circuit 5a constitutes a transmission system circuit (oscillator, multiplier, modulator, high output amplifier, etc.), and the high frequency circuit 5b constitutes a reception system circuit (low noise amplifier, mixer, etc.). The package 1 is configured such that the sealing 3 is soldered to the upper surface of the multilayer ceramic substrate 2 and the cover 100 is joined to the upper surface of the sealing ring 3 by seam welding. In the multilayer ceramic substrate 2, cavities 4a and 4b are formed. High-frequency circuits 5a and 5b are accommodated and mounted in the cavities 4a and 4b, respectively.

  The seal ring 3 is made of a conductive metal such as stainless steel or kovar, and is provided with two opening holes corresponding to the cavities 4a and 4b. The cover 100 is preferably made of a conductive member such as aluminum or kovar. Note that the cover 100 may be formed of a ceramic substrate with conductive plating applied to the entire surface. In this case, the cover 100 is joined to the multilayer ceramic substrate 2 with solder.

  The multilayer ceramic substrate 2 includes a first ceramic substrate layer 6, a second ceramic substrate layer 7, a third ceramic substrate layer 8, a fourth ceramic substrate layer 9, and a fifth ceramic substrate layer 10. Are stacked in order from the bottom. That is, the lower surface of the second ceramic substrate layer 7 is bonded to the upper surface of the first ceramic substrate layer 6, the lower surface of the third ceramic substrate layer 8 is bonded to the upper surface of the second ceramic substrate layer 7, The lower surface of the fourth ceramic substrate layer 9 is bonded to the upper surface of the third ceramic substrate layer 8, and the lower surface of the fifth ceramic substrate layer 10 is bonded to the upper surface of the fourth ceramic substrate layer 9. The upper surface of the fifth ceramic substrate layer 10 is bonded to the lower surface of the seal ring 3.

  Opening holes (cavities) provided in the second and third ceramic substrate layers 7, 8, opening holes (cavities) provided in the fourth and fifth ceramic substrate layers 9, 10, and the seal ring 2 The formed opening holes (cavities) overlap with each other, and communicate with each other vertically to form cavities 4a and 4b.

  1 and 2, the multilayer ceramic substrate 2 includes a pair of terminal blocks 12 that are exposed to the cavity space and are opposed to each other at the lower periphery of the side surfaces of the cavities 4 a and 4 b. The terminal block 12 is composed of the side walls of the second and third ceramic substrate layers 7 and 8. The terminal block 12 is disposed so as to protrude toward the cavity space with respect to the side walls of the fourth and fifth ceramic substrate layers 9 and 10 and has a shelf shape. As shown in FIG. 2C, a protruding piece 15 that forms a part of the third ceramic substrate layer 8 is provided on the side surface of the terminal block 12. The protrusion 15 has a sufficient length in the width direction so as to cover the side wall surface of the second ceramic substrate layer 7, and is bent downward from the horizontal along the side wall surface. The lower end surface of the protruding piece 15 is disposed in proximity to the upper surface of the first ceramic substrate layer 6. The height h in the vertical direction of the protruding piece 15 matches the sum t1 (for example, 0.2 to 0.3 mm) of the thicknesses of the second and third ceramic substrate layers 7 and 8, which is the height of the terminal block 12. Although it is desirable to make it short, it may be slightly shortened. The height h1 can be controlled within a range of approximately 10 μm. A grounded conductor layer 150 is formed on the surface of the protruding piece 15 on the cavity space side.

In addition, a protruding piece 25 that projects from the fourth ceramic substrate layer 9 toward the center of the cavity above the terminal block 12 at the periphery of the cavities 4 a and 4 b and forms a part of the fifth ceramic substrate layer 10. Is installed. As shown in FIG. 2C, the protruding piece 25 is bent from the horizontal to the lower side along the side wall surface so as to cover the side wall surface of the second ceramic substrate layer 9. The lower end surface of the protruding piece 25 is disposed close to the upper surface of the third ceramic substrate layer 8. That is, the height h2 in the vertical direction of the protruding piece 25 is preferably matched with the sum t2 (for example, 0.2 to 0.3 mm) of the thicknesses of the fourth and fifth ceramic substrate layers 9 and 10, It can be shortened. The height h2 can be controlled in size within a range of about 10 μm. A grounded conductor layer 250 is formed on the surface of the protruding piece 25 on the cavity space side.
In addition, exposed portions 28 where the ceramic surface of the fourth ceramic substrate layer 9 is exposed exist around the four corners of the cavities 4 a and 4 b in the fifth ceramic substrate layer 10.
In order to suppress unnecessary signals that are input from the ceramic surface of the exposed portion 28 into the package, an electromagnetic shielding wall may be configured by providing a plurality of VIA holes around the exposed portion 28. Even in this case, since the number of VIA holes provided for the purpose of electromagnetic shielding of the cavity side surface is reduced, there is a sufficient effect of reducing the time for drilling the VIA holes.

Further, in the second and fourth ceramic substrate layers 7 and 9, the side walls in the direction perpendicular to the opposing direction of the pair of terminal blocks 12 are flush with each other at the peripheral edges of the cavities 4a and 4b. Above the first ceramic substrate layer 6 on the same surface, a bent piece 26 protruding from the periphery of the cavity of the fifth ceramic substrate layer 10 is provided. As shown in FIG. 2D, the protruding piece 26 is bent from the horizontal to the lower side along the side wall surface so as to cover the side wall surfaces of the second and fourth ceramic substrate layers 7 and 9. . The lower end surface of the protruding piece 26 is disposed close to the upper surface of the first ceramic substrate layer 6. That is, the height h3 in the vertical direction of the protruding piece 26 is the sum t3 (for example, 0.2 to 0.3 mm) of the thicknesses of the second, third, fourth, and fifth ceramic substrate layers 7, 8, 9, and 10. ), But may be slightly shorter. The height h3 can be controlled within a range of approximately 10 μm. A grounded conductor layer 260 is formed on the surface of the protruding piece 26 on the cavity space side.
Further, in the vicinity of the other four corners of the cavities 4a and 4b in the fifth ceramic substrate layer 10, there are exposed portions 29 where the ceramic surface of the fourth ceramic substrate layer 9 is exposed.
In order to suppress an unnecessary signal input from the ceramic surface of the exposed portion 29 to the inside of the package, a plurality of VIA holes may be provided around the exposed portion 29 to constitute an electromagnetic shielding wall.
Further, the side walls in the direction orthogonal to the opposing direction of the pair of terminal blocks 12 do not necessarily have to be the same surface, and a shelf similar to the terminal block 12 is appropriately configured as necessary. Also good.

As shown in FIG. 2C, a conductor pad 13 and a ground conductor 14 are provided on the upper surface of the terminal block 12. The conductor pad 13 functions as a signal terminal. The ground conductor 14 is electrically connected to the conductor layer 150 to form a GND surface. The conductor pad 13, the ground conductor 14, and the conductor layer 150 are arranged in a non-contact manner and insulated with an exposed surface 18 where the ceramic surface of the third ceramic substrate layer 8 is exposed.
The distance between the end surface of the conductor pad 13 on the high frequency circuit side and the surface of the protruding piece 15 on the cavity side is preferably about 80 μm to 100 μm.

  As shown in FIGS. 1 and 2, a ground conductor layer 17 is formed on the upper surface of the first ceramic substrate layer 6, and the entire bottom surfaces of the cavities 4a and 4b form a GND surface. The upper parts of the cavities 4a and 4b are covered with a cover 100 and electromagnetically shielded.

  Further, a VIA hole for signal transmission, a VIA hole for heat conduction, and an inner layer conductor line (not shown) are disposed inside the first ceramic substrate layer 6 and are appropriately connected. A part of the conductor pad 13 in the cavity 4a is electrically connected to a part of the conductor pad 13 in the cavity 4b through a VIA hole for signal transmission, an inner layer conductor line, and the like (not shown). The other part of each of the conductor pads 13 in the cavities 4a and 4b is connected to a signal input / output terminal (external signal input) disposed outside the package 1 through a VIA hole for signal transmission, an inner layer conductor line, or the like. Output terminal) and a power supply terminal (not shown). The external signal input / output terminal and the power supply terminal are connected to a circuit board of the external unit (not shown) through a conductor terminal provided on the outer periphery of the package 1. A configuration in which a ball grid array (BGA) is interposed on the bottom surface and connected to the circuit board of the external unit by flip chip mounting may be employed.

  The high frequency circuit 5a is joined to the upper surface of the ground conductor 17 by soldering in the cavity 4a. The high frequency circuit 5b is joined to the upper surface of the ground conductor 17 by soldering in the cavity 4b. On the upper surface of the high-frequency circuits 5a and 5b, electrode terminals 50 for signal input / output, GND or power supply input are provided. The electrode terminals 50 of the high-frequency circuits 5a and 5b are appropriately connected to the conductor pads 13 and the ground conductors (ground conductors 14, 15, 17 and the like) through the conductive bonding wires 16.

The high frequency module 500 configured as described above operates as follows.
The external unit inputs / outputs control signals and RF signals to / from external signal input / output terminals. Also, a bias power supply is input to the power supply terminal. In the high-frequency circuit, control signals and RF signals are input / output to / from external signal input / output terminals via transmission lines such as inner layer lines, conductor pads, and bonding wires. In addition, the high frequency circuit receives a bias power from a power supply terminal via a transmission line such as an inner layer line, a conductor pad, and a bonding wire. Thereby, the high frequency circuit performs a required operation as an amplifier, an attenuator, an oscillator, or the like, and performs amplification of the input signal, amplitude adjustment of the input signal, output of the high frequency oscillation signal, and the like.

  At this time, the high-frequency circuit 5a in the cavity 4a and the high-frequency circuit 5b in the cavity 4b need to be iridinated with each other in a desired operating frequency band. In the cavity 4a, an unnecessary radiation signal in a high frequency band is generated from a bonding wire or an electrode terminal. When this unnecessary radiation signal is input into the multilayer ceramic substrate 2 from the side walls of the inner periphery of the cavities 4a and 4b, it propagates through the inner layer of the package 1. The high-frequency signal propagated through the inner layer of the package 1 passes through the inside of the package 1 and is re-radiated in the space of another cavity, and is coupled to the high-frequency circuit in the other cavity. Alternatively, signal loss occurs due to radiation outside the package. In this case, the high-frequency characteristics and operating characteristics of the high-frequency circuits 5a and 5b are deteriorated, so that the performance is not satisfied and a malfunction may occur.

  Therefore, the high-frequency module 500 according to this embodiment is arranged in another cavity by arranging a conductor layer on the side wall surface of the inner periphery of the cavities 4a and 4b and shielding the inner wall surface of the cavity space with a conductor. It is possible to suppress interference with the high frequency circuit and suppress leakage of the high frequency signal to the outside of the package.

  Further, at this time, the conductor layer provided on the side wall surface of the inner periphery of the cavities 4a and 4b is not directly attached to the cut surface (uneven surface with rough surface roughness) of the opening hole of the ceramic substrate layer. It is formed on the smooth surface of each protruding piece (15, 25, 26) that is bent in step (b). The conductor layer on the surface of each protruding piece can be formed by printing a conductor film (application of a conductor paste) before the multilayer ceramic substrate is laminated, and does not peel off after printing.

Next, a manufacturing method of the multilayer ceramic substrate 2 according to the first embodiment will be described.
FIG. 3 is a diagram showing a manufacturing flow of the multilayer ceramic substrate 2.
In the figure, in step S101, a ceramic green sheet (hereinafter referred to as green sheet) is manufactured. The green sheet is obtained by using a ceramic material containing a glass component, an organic binder, and a plasticizer, extending to a predetermined thickness by a doctor blade method, and drying. Prepare as many green sheets as you want to stack. Thereafter, in step S102, each green sheet is cut into a desired shape that is easy to handle. Each green sheet prepared here has a size of about 200 mm square and a thickness of about 0.1 mm.

  Next, in step S103, a VIA hole is formed by punching using a die punch. Further, through holes (pin holes) for alignment are provided at the four corners of the green sheet. Subsequently, in S104, a conductor paste is printed and filled in each VIA hole by squeezing through a metal mask. Thereafter, in step S105, a conductor pattern that forms a required circuit pattern is formed by screen-printing a conductor paste through a mesh screen using the pin hole as a position reference.

  Next, in step S106, an opening hole is formed to form a cavity using the pin hole 60 as a position reference. Next, in step S107, a predetermined plurality of green sheets are stacked in a predetermined stacking order. At this time, the green laminate corresponding to the first ceramic substrate layer 6, the second ceramic substrate layer 7, and the third ceramic substrate layer 8 is sequentially laminated from the bottom, and the primary lamination is performed. Form body 21. The second ceramic substrate layer 7 and the third ceramic substrate layer 8 are laminated with the pin hole 60 as a position reference so that the respective opening holes constituting the cavity coincide with each other.

  Then, in process S107, the primary laminated body 21 is compression-molded using an isostatic pressing method. Here, after the primary laminate is waterproof-packaged, it is immersed in a high-temperature bath and subjected to compression molding with hydrostatic pressure. Thereby, the binder of each green sheet which comprises the primary laminated body 21 fuses, and it becomes an integrated green sheet laminated body. After the treatment, the primary laminate 21 that is waterproof-packed from the hot tub is taken out and opened.

  Next, in step S109, a predetermined plurality of green sheets are stacked in a predetermined stacking order on the primary laminate 21 after compression molding. Here, on the primary laminate 21, the corresponding green sheets are laminated in order from the bottom on the fourth ceramic substrate layer 9 and the fifth ceramic substrate layer 10, respectively. The laminated body 22 is formed. The primary laminated body 21, the fourth ceramic substrate layer 9, and the fifth ceramic substrate layer 10 are laminated with the pin hole 60 as a position reference so that the respective opening holes constituting the cavity coincide with each other. Is done.

  Then, in process S110, the secondary laminated body 22 is compression-molded using an isostatic pressing method. Here, after the secondary laminate 22 is waterproof-packaged, it is immersed in a high-temperature bath and subjected to a compression molding process by hydrostatic pressure. Thereby, the binder of each green sheet which comprises the secondary laminated body 22 fuse | melts, and it becomes an integrated green sheet laminated body. After the treatment, the secondary laminated body waterproof-packed is taken out from the hot tub.

  Subsequently, in step S111, the secondary laminated body 22 after the compression molding is cut into a predetermined size by cutting an end using a cutting device. Thereafter, the secondary laminate 22 is sintered in a temperature-controlled sintering furnace to form a multilayer ceramic substrate. In the case of LTCC, a glass material is added to the substrate material, and sintering is performed at a temperature of 800 ° C. to 1000 ° C.

  Furthermore, in step S112, a predetermined plating process is performed on the sintered multilayer ceramic substrate. When a plurality of manufactured products are included in the sintered multilayer ceramic substrate after the plating treatment, the final multilayer ceramic substrate 2 is obtained by cutting into pieces by a cutting device.

  Next, steps S106, S108, and S110 of the manufacturing flow shown in FIG. 3 will be described in more detail below with reference to FIGS.

First, the cavity drilling process will be described.
FIG. 4 is a diagram showing the shape of each green sheet that has been subjected to cavity drilling in step S106.
FIG. 4A shows the shape of the green sheet constituting the second ceramic substrate layer 7. In the figure, opening holes 7a and 7b are formed, and punching is performed so that pin holes 60 are provided at the four corners of the green sheet. A plurality of the green sheets are laminated to constitute the second ceramic substrate layer 7.

  FIG. 4B shows the shape of the green sheet constituting the third ceramic substrate layer 8. In the figure, opening holes 8a and 8b are formed, and punching is performed so that pin holes 60 are provided at the four corners of the green sheet. A protruding piece 15 is attached to one side of the opening holes 8a and 8b. The opening holes 8a and 8b are punched with a punch smaller than the opening holes 7a and 7b by a required size. Furthermore, at the four corners of the opening holes 7a and 7b, portions where both ends of the projecting piece 15 intersect are punched with a sufficiently small punch. Further, when the projecting pieces 15 are bent along the broken lines in the figure, the centers of the opening holes 8a and 8b are processed so as to coincide with the centers of the opening holes 7a and 7b. In consideration of the bending allowance, the widths of the opening holes 8a and 8b after bending are smaller than the widths of the opening holes 7a and 7b by the thickness of the third ceramic substrate layer 8.

  FIG. 4C shows the shape of the green sheet constituting the fourth ceramic substrate layer 9. In the figure, opening holes 9a and 9b are formed, and punching is performed so that pin holes 60 are provided at the four corners of the green sheet. A plurality of the green sheets are laminated to constitute the fourth ceramic substrate layer 9.

FIG. 4D shows the shape of the green sheet constituting the fifth ceramic substrate layer 10. In the figure, opening holes 10a and 10b are formed, and punching is performed so that pin holes 60 are provided at the four corners of the green sheet. A protruding piece 25 and a protruding piece 26 are respectively attached to the two opposite sides of the opening holes 10a and 10b. The opening holes 10a and 10b are punched with a punch smaller than the opening holes 9a and 9b by a required size. Further, at the four corners of the opening holes 10a and 10b, portions where the protruding pieces 25 and the protruding pieces 26 intersect are punched with a sufficiently small punch. Further, when the protruding pieces 25 and 26 are bent along the broken line in the drawing, the center of the opening holes 10a and 10b is processed so as to coincide with the center of the opening holes 9a and 9b. When the bending allowance is taken into consideration, the width of the opening holes 10a and 10b after bending is smaller than the width of the opening holes 9a and 9b by the thickness of the third ceramic substrate layer 8.
As described above, the opening holes 7a and 7b, the opening holes 8a and 8b, the opening holes 9a and 9b, and the opening holes 10a and 10b are stacked in step S109 so as to overlap each other on the basis of the pin hole 60. The cavities 4a and 4b are configured respectively.

Next, details of the compression molding process will be described.
FIG. 5 is a diagram showing details of the manufacturing flow in the compression molding process of steps S108 and S110. In steps S108 and S110, the same processing is performed on the primary stacked body 21 and the secondary stacked body 22. Therefore, in the description here, as a representative example, the processing of the secondary stacked body 22 after the secondary stacking is performed. explain.
FIG. 6 is a perspective view showing a state in which the secondary laminate 22 is wrapped with a packaging material.
FIG. 7 is a view showing a state in which the secondary laminate 22 is wrapped in a packaging material and then immersed in a high-temperature bath.

  In the figure, in step S121, a flat plate 32 is laid on the upper surface of the secondary laminate 22. The flat plate 32 has a smooth flat surface and is formed of a metal material having a desired plate thickness. A resin material may be used for the flat plate 32. The flat plate 32 has an opening hole having the same opening width as that of the ceramic green sheet constituting the second ceramic substrate layer 7. The opening hole of the flat plate 32 is arranged on the upper surface of the ceramic green sheet constituting the third ceramic substrate layer 8 at a position matching the opening hole of the ceramic green sheet constituting the second ceramic substrate layer 7. In the four corners of the flat plate 32, penetrating pin holes are provided at the same positions as the pin holes 60 provided in each green sheet of the secondary laminate 22. Therefore, alignment with the cavities 4a and 4b of the secondary laminate 22 is performed with reference to the pin holes. This alignment is performed using a laminated tool 73 in which four pins 74 are installed at four corners. The secondary laminate 22 is placed on the laminating tool 73.

  Next, in step S <b> 122, the buffer material 33 is laid on the upper surface of the flat plate 32. The buffer material 33 is preferably a gel-like sheet based on a silicon resin, but may be a rubber sheet based on a silicon resin. The buffer material 33 has a function of preventing the shape of the secondary laminated body 22 in which the cavities 4a and 4b are formed from being deformed.

  Then, in process S123, the secondary laminated body 22 is accommodated in the packaging material 200 which consists of an aluminum thin film with the lamination tool 73, and is packaged. Next, the inside of the packaging material 200 is brought into a vacuum state by closely packaging the opening holes of the packaging material 200 and vacuum packaging. The packaging material 200 has a function of preventing displacement of the cushioning material 33 and waterproofing.

Furthermore, in step S <b> 124, the secondary laminate 22 packaged with the packaging material 200 is submerged in the high-temperature bath 210. The hot water bath 220 is filled with hot water 220, and the secondary laminate 22 packaged with the packaging material 200 is immersed in the hot water 220 for a predetermined time. Inside the packaging material 200, the hydrostatic pressure 40 is equally applied to the secondary laminate 22.
At this time, the packaging material 200 and the cushioning material 33 receive pressure from the surroundings, and are brought into close contact with the shape of the secondary laminate 22 and partially expand and contract. In addition, since the packaging material 200 and the buffer material 33 expand and contract on the inner walls of the cavities 4a and 4b, there is an area where the contact with the secondary laminate 22 is not sufficient, and compression molding is performed in this state. As a result, in step 121, the flat plate 32 is placed on the upper surface of the uppermost layer of the secondary laminate 22 so that the portions of the packaging material 200 and the buffer material 33 that are not extended do not change the shape of the cavities 4 a and 4 b. It is on. As a result, pressure is uniformly applied to the surface of the secondary laminate 22, and it is possible to avoid pressure concentration on the stepped portions of the cavities 4a and 4b. Can be prevented.
Finally, in process S125, the secondary laminated body 22 packaged with the packaging material 200 is taken out from the high temperature bath 210. Thereafter, the packaging material 200 is opened, and the laminate 22 is taken out from the packaging material 200.

Next, the hydrostatic press process of process S108 after the process of process S107 will be described in further detail.
FIG. 8 is a diagram showing the operation of the hydrostatic pressure pressing step for the primary laminate, and FIG. 8A shows the state before the hydrostatic press of the primary laminate 21 in step S122, and FIG. ) Shows the state at the time of hydrostatic pressure pressing in step S124. In the figure, illustration of the packaging material 200 is omitted.
In FIG. 8, in step S <b> 107, the green sheet 61 is laminated on the upper surface of the lamination tool 70.
Next, the green sheet 62 is laminated on the upper surface of the green sheet 61, and the green sheet 63 is laminated on the upper surface of the green sheet 62. The green sheets 61, 62, 63 constitute the first ceramic substrate layer 6.
Further, the green sheet 71 is laminated on the upper surface of the green sheet 63, and the green sheet 72 is laminated on the upper surface of the green sheet 71. The first ceramic substrate layer 6 and the green sheets 71 and 72 constitute the second ceramic substrate layer 7.
Further, a green sheet constituting the third ceramic substrate layer 8 is laminated on the upper surface of the green sheet 72, and a conductor layer 81 is attached to the upper surface. The first ceramic substrate layer 6, the second ceramic substrate layer 7, and the third ceramic substrate layer 8 constitute hollow cavities 41a and 41b.

  At this time, since the lamination tool 70 has pins 71 installed at the four corners, the pin hole 60 of each green sheet is inserted into the pin 71 of the lamination tool 70 to generate the primary laminated body 21. A flat plate 30 is laid on the uppermost layer of the primary laminate 21. Further, a buffer material 31 is laid on the flat plate 30.

In FIG. 8A, the protruding piece 15 of the third ceramic substrate layer 8 stacked on the uppermost layer protrudes in the horizontal direction in the space of the cavities 41a and 41b.
Here, the hydrostatic press is performed in step S124, and the pressure 40 is uniformly applied to the cavities 41a and 41b, so that in the compression molding process, as shown in FIG. It is pushed and bent downward along the cavity wall surface. The pushed and bent projecting piece 15 strikes the cavity wall surface and is formed into a flat shape. Thereby, the conductor layer 81 is formed on the side surface along the cavity wall surface. At the same time, each green sheet is compressed at this point.

Next, the hydrostatic press in step S110 after the process in step S109 will be described in further detail.
FIG. 9 is a diagram showing the operation of the hydrostatic press of the secondary laminate, and FIG. 9A shows the state before the hydrostatic press of the secondary laminate 22 in step S122, and FIG. Indicates the state during the hydrostatic pressing in step S124.
In FIG. 9, in step S <b> 109, the primary laminate 21 is laminated on the upper surface of the lamination tool 73.
Next, the green sheet 91 is laminated on the upper surface of the primary laminate 21, and the green sheet 92 is laminated on the upper surface of the green sheet 91. The green sheets 91 and 92 constitute the fourth ceramic substrate layer 9.
Further, the green sheet constituting the fifth ceramic substrate layer 10 is laminated on the upper surface of the green sheet 92, and the conductor layer 101 is attached to the upper surface. The first ceramic substrate layer 6, the second ceramic substrate layer 7, the third ceramic substrate layer 8, and the fourth and fifth ceramic substrate layers 9, 10 that are primarily laminated are formed of hollow cavities 4 a, 4 b. Is configured.
At this time, the pinhole 60 of each green sheet is inserted into the pin 74 of the lamination tool 73 to generate the secondary laminated body 22. As described above, the flat plate 32 is laid on the uppermost layer of the secondary laminate 22. Further, a buffer material 33 is laid on the flat plate 32.

In FIG. 9A, in the fifth ceramic substrate layer 10 laminated on the uppermost layer, the protruding pieces 25 protrude in the horizontal direction in the spaces of the cavities 4a and 4b.
Here, hydrostatic pressing is performed in step S124, and pressure 40 is evenly applied to the cavities 4a and 4b, so that in the compression molding process, as shown in FIG. It is pushed and bent downward along the cavity wall surface. The projecting piece 25 that has been pushed and bent strikes the cavity wall surface and is formed into a flat shape. As a result, the conductor layer 101 is formed on the side surface along the cavity wall surface. At the same time, each green sheet is compressed at this point. In addition, since the third ceramic substrate layer 8 has already been compressed at the time of compression molding of the primary laminate, there is no shape collapse at the step portion of the cavity wall surface.
This step portion constitutes the terminal block 12, but since there is no shape collapse at this portion, the size of the ceramic substrate layer being crushed at the corner of the terminal block 12 becomes small. Therefore, when a bonding wire is connected to the conductor pad 13, the wire length can be shortened as much as possible by bringing the connection point of the wire closer to the corner edge of the terminal block 12.

The protruding piece 26 is also pushed and bent from the horizontal direction to the downward direction along the cavity wall surface in the same manner as the protruding piece 25.
In addition, since the bending process of the protruding pieces 15, 25, and 26 is performed in the process of a series of compression molding processes of a green sheet that is normally performed, no special processing process is added during the bending process. .

As described above, in this embodiment, since it is not necessary to form a half three hole on the side surface of the cavity, it is possible to avoid cracks in the substrate due to firing shrinkage.
Further, since metalizing on the side surface of the cavity becomes unnecessary, peeling of the conductor layer on the side surface of the cavity is suppressed.

Furthermore, compared to the conventional general manufacturing method, for example, after forming the cavity, printing a conductor on the side surface of the cavity, or filling the half half-hole with a conductor and then sintering, metalizing and through-holes are compared. Processing steps can be reduced.
In addition, since the conductor layer can be easily formed on the cavity wall surface by the manufacturing method according to this embodiment, a low-temperature fired multilayer ceramic substrate with improved electromagnetic shielding effect in the cavity can be easily obtained.

Embodiment 2. FIG.
10 is a perspective view showing a configuration of a high-frequency module 502 according to Embodiment 2 of the present invention.
In the figure, the high frequency module 502 includes a multilayer ceramic substrate 151 and a high frequency circuit 152 flip-chip mounted on the upper surface of the multilayer ceramic substrate 151. The multilayer ceramic substrate 151 is formed by LTCC. The multilayer ceramic substrate 151 has a plurality of grooves 153 formed on the side surface of the substrate. A conductor layer 154 formed in a planar shape is disposed in the groove 153 to form a side groove pattern structure. A conductor line 155 is disposed on the upper surface of the multilayer ceramic substrate 151. The high-frequency circuit 152 is provided with a plurality of terminals on the back surface (not shown). The back surface of the high-frequency circuit 152 is bump-connected to the conductor line 155 via the BGA.

  The multilayer ceramic substrate 151 is mounted on the external circuit substrate 160. The external circuit board 160 has a conductor line 161. The conductor layer 154 is soldered to the terminal of the conductor line 161, whereby the high frequency circuit 152 and the external circuit board 160 are electrically connected.

The high-frequency module 502 according to the second embodiment is configured as described above and operates as follows.
A high-frequency signal and a signal transmission of a power source are performed between the external circuit board 160 and the high-frequency circuit 152 with the conductor line 161, the conductor layer 154, and the conductor line 155 interposed therebetween. Thereby, the high frequency circuit 152 performs a desired operation.

  FIG. 11 is a diagram showing a part of the method for manufacturing the multilayer ceramic substrate 151 according to the second embodiment. The multilayer ceramic substrate 151 of this embodiment can be manufactured by dividing and cutting (dividing) after forming a multilayer ceramic substrate having a cavity structure. The difference from the first embodiment is that the cavity penetrates in the vertical direction of the substrate, but a multilayer having a through cavity structure as shown in FIG. A ceramic substrate 170 can be manufactured. In this embodiment, as shown in FIG. 11 (b), a side-surface groove pattern structure such as castellation is formed by cutting the formed multilayer ceramic substrate at a through cavity portion. .

  In FIG. 11A, a multilayer ceramic substrate 170 is formed by laminating a ceramic substrate layer 172 on an upper layer of a ceramic substrate layer 171 laminated in a plurality of layers. At this time, the ceramic substrate layer 172 has a protruding piece 173 bent along the side surface of the through cavity 175. A conductor layer 176 is formed on the protruding piece 173 on the surface layer facing the space of the through cavity.

The multilayer ceramic substrate 170 will be briefly described as follows.
A circuit pattern for each place is printed on a plurality of green sheets. Through holes 175 are formed in the ceramic substrate layer 171 by punching a plurality of printed green sheets with a punch. Next, a green sheet punched with a punch smaller than the required punching shape is stacked on the uppermost layer. This green sheet constitutes the ceramic substrate layer 172. The green sheet laminate thus laminated is then compression molded.

  In compression molding, a flat plate of a metal plate for maintaining the cavity shape is laid from the uppermost layer of the laminate, and then a buffer material is laid. At this time, the protruding piece 173 of the ceramic substrate layer 172 protrudes hollow into the through cavity 175. In this state, the laminate is packaged and subjected to an isostatic pressing process. The protruding piece 173 is pressed and bent along the side surface of the substrate by an isostatic pressing process, and is formed into a flat shape. Since the conductor layer 176 is provided on the protruding piece 173 in advance at the stage of printing the circuit pattern, the conductor layer 176 is formed in a planar shape along the side surface of the substrate. The laminate subjected to the isostatic pressing is put into a sintering furnace and sintered.

  As shown in FIG. 11B, the multilayer ceramic substrate 170 is cut into a substrate 151a and a substrate 151b on a cross-sectional line EE connecting a plurality of through cavities. As a result, a multilayer ceramic substrate 151 having a side groove pattern structure 180 as shown in FIG. 11C is formed. The multilayer ceramic substrate 151 can constitute a plurality of grooves 153 formed on the outer peripheral side surface of the substrate and a conductor layer 154 disposed in the groove 153 on the outer peripheral side surface of the substrate by dividing the through cavity.

The above-described method for manufacturing a multilayer ceramic substrate eliminates the need for a castellation structure, and thus avoids cracks in the substrate when shrinking by firing.
In addition, a multilayer ceramic substrate having a conductor on the side surface of the substrate can be easily formed so as to ensure electrical characteristics.

As a result, a plurality of casters can be produced in comparison with the conventional method for forming a wall surface, which is obtained by, for example, printing and filling a castellation conductor, firing, and dividing a substrate after forming a castellation. The processing steps for obtaining the construction structure can be reduced.
In addition, it is possible to easily form a multilayer ceramic substrate having a conductor on the cavity wall surface that can ensure electrical characteristics.

1 is a diagram showing a configuration of a high-frequency module according to Embodiment 1. FIG. 1 is a diagram showing a configuration of a multilayer ceramic substrate according to Embodiment 1. FIG. FIG. 3 is a diagram showing a manufacturing flow of the multilayer ceramic substrate according to the first embodiment. It is a figure which shows the shape of the green sheet by Embodiment 1. FIG. 3 is a diagram showing a manufacturing flow of compression molding according to Embodiment 1. FIG. It is a figure which shows the state which wrapped the laminated body with the packaging material. It is a figure which shows the state which sunk the packaging material which wrapped the laminated body in the high temperature bathtub. It is a figure which shows the hydrostatic pressure press process of a primary laminated body. It is a figure which shows the isostatic pressing process of a secondary laminated body. It is a figure which shows the structure of the high frequency module by Embodiment 2. FIG. It is a figure which shows the structure of the multilayer ceramic substrate by the mounting form 2.

Explanation of symbols

  2 multilayer ceramic substrate, 4a, 4b cavity, 5a, 5b high frequency circuit, 6 first ceramic substrate layer, 7 second ceramic substrate layer, 7a, 7b opening hole, 8 third ceramic substrate layer, 8a, 8b opening Hole, 9 4th ceramic substrate layer, 9a, 9b opening hole, 10th ceramic substrate layer, 10a, 10b opening hole, 15 protruding piece, 25 protruding piece, 26 protruding piece, 151 multilayer ceramic substrate, 152 high frequency circuit , 153 groove, 154 conductor layer, 173 protruding piece, 150 conductor layer, 250 conductor layer, 260 conductor layer, 500 high-frequency module, 502 high-frequency module, S124 hydrostatic pressure press.

Claims (7)

A first ceramic substrate layer;
A second ceramic substrate layer laminated on the first ceramic substrate layer and having a cavity formed therein;
The second ceramic substrate layer has a protruding piece formed on the surface of the second ceramic substrate layer and bent along the cavity side surface of the second ceramic substrate layer. A third ceramic substrate layer formed with a cavity communicating with the cavity of the substrate layer;
Multi-layer ceramic substrate with A first ceramic substrate layer having a groove formed on a side surface;
A second ceramic substrate that is laminated on the first ceramic substrate layer and has a protruding piece that is bent along the inner surface of the groove on the side surface of the first ceramic substrate layer and has a surface conductor layer formed as a part of the layer. Layers,
Multi-layer ceramic substrate with A first ceramic substrate layer;
A second ceramic substrate layer laminated on the first ceramic substrate layer and having a cavity formed therein;
The second ceramic substrate layer has a protruding piece formed on the surface of the second ceramic substrate layer and bent along the cavity side surface of the second ceramic substrate layer. A third ceramic substrate layer formed with a cavity communicating with the cavity of the substrate layer;
A high-frequency circuit housed in the cavity of the second ceramic substrate layer and mounted on the first ceramic substrate;
High frequency module with A first ceramic substrate layer having a groove formed on a side surface;
A protruding piece having a surface conductor layer formed on the first ceramic substrate layer and bent along the inner surface of the groove on the side surface of the first ceramic substrate layer and electrically connected to the external circuit board is formed. A second ceramic substrate layer in part of the layer;
A high frequency circuit mounted directly or indirectly on the second ceramic substrate layer and electrically connected to the surface conductor layer of the second ceramic substrate layer;
High frequency module with A second ceramic green sheet laminated on the first ceramic green sheet and formed with an opening hole; and a third ceramic green sheet formed with an opening hole having a protruding piece formed with a surface conductor layer on the periphery; Laminating process to obtain a laminate by laminating the opening holes of each other,
A compression molding step of pressing and bending the protruding piece of the third ceramic green sheet in the laminated body along the side surface of the opening hole of the second ceramic green sheet;
A sintering step of firing the laminate,
The manufacturing method of the multilayer ceramic substrate shape | molded in order. The compression molding step is
6. The method for producing a multilayer ceramic substrate according to claim 5, wherein the laminated body is pressed together with the protruding piece by an isostatic press. The compression molding step is
A metal plate having an opening hole having the same opening width as that of the second ceramic green sheet is arranged on the upper surface of the third ceramic green sheet at a position where the opening hole matches the opening hole of the second ceramic green sheet. Process,
A step of wrapping the laminate with a waterproof material after covering the upper surface of the laminate on which the metal plate is disposed with a cushioning material;
A step of pressing the packaged laminate with a hydrostatic pressure press,
6. The method for producing a multilayer ceramic substrate according to claim 5, wherein the multilayer ceramic substrate is formed in the following order.

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