JPH10189869A - High-frequency module substrate and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency module substrate suitable for mass production, moreover capable of miniaturizing and reducing mutual interferences between respective functional blocks. SOLUTION: This high-frequency module substrate is provided with a dielectric substrate 1 with various circuit elements packaged on the main surface thereof, dielectric walls 2 erected for the formation of a plurality of cavities on the main surface of the dielectric substrate 1, grounding electrodes 81 provided on the main surface of the dielectric substrate 1, vertical grounding electrodes 21 with its upper part exposed from the upper end of the dielectric walls 2 and connecting to the grounding electrodes 81 on the lower ends thereof and a seal cap 71 made of conductive material covering the plurality of cavities, furthermore connecting to the upper ends of the vertical grounding electrodes 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency module board, and more particularly to a high-frequency module board used for a high-frequency circuit board used in a high-frequency circuit radio such as a portable communication telephone.

[0002]

2. Description of the Related Art In a conventional high-frequency circuit board, pads and ground electrodes for mounting various circuit elements are formed on the surface of a laminated board made of glass epoxy resin or the like. For example, as circuit elements used in a mobile communication device or the like, elements constituting each functional block such as a power amplifier block and a synthesizer block are mounted, and each block is separated by a ground electrode.

[0003]

In the above-described high-frequency circuit board, although each functional block is separated by using a ground electrode, there is a possibility that electromagnetic waves may cause interference through a space or the inside of the board. For example, there has been a problem that the oscillation frequency of the frequency synthesizer block fluctuates due to interference of electromagnetic waves from other functional blocks. Further, in order to reduce the interference of electromagnetic waves between the respective functional blocks, it is conceivable to dispose the respective functional blocks apart from each other. However, the circuit board is enlarged to meet the demand for miniaturization of the device. You will not be able to do it.

An object of the present invention is to provide a high-frequency module substrate which can be reduced in size, can reduce mutual interference between functional blocks, and is suitable for mass production.

[0005]

A high-frequency module substrate according to the present invention includes a dielectric substrate, a dielectric wall, a ground electrode, a vertical ground electrode, and a seal cap. The dielectric substrate is formed by laminating ceramic dielectric layers, and various circuit elements are mounted on the main surface. The dielectric wall is used to form a plurality of cavities in the main surface of the dielectric substrate.
It is erected on a dielectric substrate. The ground electrode is provided on the main surface of the dielectric substrate. The vertical ground electrode has an upper end exposed from the upper end of the dielectric wall and a lower end connected to the ground electrode. The seal cap is connected to the upper end of the vertical ground electrode, and is made of a conductive material that covers the plurality of cavities.

[0006] With this configuration, the electromagnetic waves of each functional block mounted in a plurality of cavities, in which the vertical ground electrode and the seal cap are fixed at the ground potential, can be sealed in the cavities. Mutual interference can be reduced. The vertical ground electrode may be configured such that its middle part is buried inside the dielectric wall. Further, the vertical ground electrode may have a configuration in which a lower end portion crosses the ground electrode and protrudes into the dielectric substrate. In this case, mutual interference between the functional blocks due to the propagation of the electromagnetic wave through the inside of the dielectric substrate can be reduced.

A method for manufacturing a high-frequency module substrate according to the present invention comprises the steps of: (a) applying a conductive paste to a main surface of a dielectric substrate to form pads and ground electrodes for mounting circuit elements; (B) A slip containing at least an insulating layer material made of ceramic or glass ceramic and a photocurable resin is applied on the main surface of the dielectric substrate, and further dried to form an insulating layer molded body. And (c) exposing and developing the insulating layer molded body to form a through hole for a cavity and a through hole for an electrode, filling the through hole for an electrode with a conductive paste, and curing or curing the through hole for a cavity. Filling a resin paste containing a thermosetting monomer, and curing the resin paste by exposure or heating; and (d) forming an insulating layer by the slip. Is repeated and the step (c) is repeated to form a laminated molded body for a dielectric wall, and at the same time, it is electrically connected to the ground electrode, and the upper end is exposed from the upper part of the laminated molded body for the dielectric wall. Forming a vertical ground electrode; and (e) sintering a laminate in which an insulating layer molded body is laminated on the dielectric substrate at a predetermined temperature to scatter the resin paste filled in the cavity through-hole. And (f) after mounting various circuit elements on the main surface of the dielectric substrate inside the cavity, the conductive material is connected to the upper end of the vertical ground electrode, and covers the plurality of cavities. Providing a seal cap.

According to the method for manufacturing a high-frequency module substrate of the present invention as described above, a high-frequency module substrate that is easy to manufacture, has excellent mass productivity, and is suitable for miniaturization can be manufactured. (G) a step of preparing a slip containing at least an insulating layer material made of ceramic or glass ceramic, and a photocurable resin; and (h) applying the slip and drying to form an insulating layer molded body. Forming; and (i) subjecting the insulating layer molded body to an exposure treatment;
Curing the insulating layer molded body, (j) the above (h),
Forming a dielectric substrate by sequentially repeating the step (i). in this case,
The manufacturing process of the high-frequency module substrate has been simplified,
Mass productivity is improved.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A high-frequency module substrate to which one embodiment of the present invention is applied will be described with reference to FIG. This high-frequency module substrate has a dielectric substrate 1 formed by laminating a plurality of ceramic dielectric layers. On the main surface of the dielectric substrate 1, a dielectric wall 2 made of the same material as the dielectric substrate 1 is provided upright. Above the main surface of the dielectric substrate 1, a plurality of cavities 51 divided by the dielectric wall 2 are formed. The main surface of the dielectric substrate 1 constituting each cavity 51 is an area in which a circuit element constituting each functional block such as a power amplifier block and a synthesizer block used in a mobile communication device is mounted. ing. In each area of the main surface of the dielectric substrate 1, pads (not shown) for mounting circuit elements constituting the functional blocks and ground electrodes 81 located around the pads are provided.
It is formed by printing a conductive material.

[0010] Such a high-frequency module substrate can be produced as follows. First, as shown in FIG. 2, an insulating layer molded body 10d is formed on a supporting substrate 9 such as glass or ceramic.
To form This insulating layer molded body 10d is coated, for example, with a slip material obtained by homogeneously kneading a ceramic material, a photocurable resin, an organic binder, and an organic solvent or water so that the film thickness after drying is 40 to 200 μm. , Dried and formed. Photocurable resins include monomers and oligomers.

The ceramic material is a composite oxide containing at least Mg, Ti, and Ca as metal elements, and the composition formula of the metal element oxide is (1-x) M
gTiO ₃ -xCaTiO ₃ (where x represents a weight ratio, and 0.01 ≦ x ≦ 0.15).
Relative to 0 parts by weight, the boron-containing compound in terms _of B ₂ O ₃ 3
It is desirable to add and contain an alkali metal-containing compound in an amount of 1 to 25 parts by weight in terms of an alkali metal carbonate in an amount of from 30 to 30 parts by weight. In this case, the Q value at the measurement frequency of 7 GHz is 1300 or more, and Au at a low temperature of 850 to 1050 ° C.
It can be co-fired with a conductive paste containing Cu or Ag as a main component, so that an electronic component or substrate having a high Q value and excellent in a high frequency region can be obtained. In the case of this composition, the Q value at the measurement frequency of 7 GHz can be 3000 or more, particularly 5000 or more.

Another ceramic material is a composite oxide containing at least Ca and Zr as metal elements.
When expressed as ZrO ₂ , x is 0.87 ≦ x ≦ 1.3.
6, based on 100 parts by weight of the main component satisfying 6, the boron-containing compound is added and contained in the range of a part by weight in terms of B ₂ O ₃ , and the alkali metal-containing compound in the range of b parts by weight in terms of alkali metal carbonate, And a and b are 0 ≦ a ≦ 30, 0 ≦ b
Some satisfies ≦ 20 and 1.5 ≦ a + b. In this case, at a relatively low temperature of about 900 to 1050 ° C., a conductor metal such as Ag-based, Cu-based, or Au-based can be fired at the same time and a dielectric ceramic having a relative permittivity εr suitable for the frequency used can be selected. It has features such as a high Q value.

Further, at least Ba, T
i is a composite oxide containing i, and when a composition formula based on these molar ratios is expressed as BaO · x (Ti _1-a Zr _a ) O ₂ , the x and a are 3.5 ≦ x ≦ 4.5, 0 ≦ a ≦
Relative to 100 parts by weight of the main component which satisfies 0.20, 4 to 30 parts by weight of zinc-containing compound calculated as ZnO, 1-20 parts by weight of a boron-containing compound in terms _of B ₂ O _3, the alkali metal-containing compound alkali Some include 1 to 10 parts by weight in terms of metal carbonate. In this case, the relative dielectric constant is 20 to 4
0, the Qf value was 30000 [GHz] or more, and -4
The temperature coefficient τf of the resonance frequency in the temperature range of 0 to 85 ° C.
It is possible to set the firing temperature within the range of 40 to +40 [ppm / ° C.] and the firing temperature at 950 ° C. or lower. Can be formed. Examples of the alkali metal include Li, Na, and K.

In addition to the above-mentioned ceramic materials, the constituent materials of the slip material include a photocurable resin which is lost by sintering, an organic binder, and further, an organic solvent or water. A slip material containing an organic solvent is called a solvent-based slip material, and a slip material containing water is called a water-based slip material.In the solvent-based slip material and the water-based slip material, the photocurable resin and the organic binder are slightly mixed. different.

The organic solvent or water mainly adjusts the viscosity of the slip and the like, and is completely lost during the binder removal in the firing step. The photocurable resin of the solvent-based slip material must have excellent thermal decomposability in order to cope with a low-temperature and short-time baking process. As a photo-curable resin, a monomer that needs to be photopolymerized by exposure after application and drying of a slip material, capable of forming free radicals and chain-growth addition polymerization, and having a secondary or tertiary carbon For example, alkyl acrylates such as butyl acrylate having at least one polymerizable ethylenic group and the corresponding alkyl methacrylates are effective. Further, polyethylene glycol diacrylates such as tetraethylene glycol diacrylate and methacrylates corresponding thereto are also effective. The photocurable resin is cured by exposure, and is added in a range such that portions other than the exposure can be easily removed by development.
5 parts by weight or less.

The organic binder of the solvent-based slip material must have good thermal decomposability like the photocurable resin. At the same time, because it determines the viscosity of the slip, wettability with solids must also be emphasized. According to studies by the present inventors, carboxyl groups such as acrylic acid or methacrylic acid-based polymers, alcoholic hydroxyl groups Preferred are ethylenically unsaturated compounds with The addition amount is preferably 25 parts by weight or less based on 100 parts by weight of the solid content.

The photocurable resin and the organic binder of the aqueous slip material must be water-soluble, and a hydrophilic functional group, for example, a carboxyl group is added to the resin and the organic binder. The amount of addition is 2 to 300, and preferably 5 to 100 in terms of acid value. If the added amount is small, the solubility in water and the dispersibility of the solid component powder become poor, and if the added amount is large, the thermal decomposability becomes poor. in view of,
It is appropriately added within the above range.

In any of the slip materials, the photocurable resin and the organic binder must have good thermal decomposability as described above.
It must be capable of thermal decomposition below ℃. More preferably, those which can be thermally decomposed at 500 ° C. or lower are preferable. If the thermal decomposition temperature exceeds 600 ° C., it remains in the dielectric layer, is trapped as carbon, changes the color of the dielectric layer to gray, and lowers the insulation resistance of the dielectric layer. In addition, it may become a void and cause delamination.

As a slip material, a sensitizer, a photo-initiating material or the like may be added as required. For example, the photoinitiating material includes benzophenones, acyloin ester compounds, and the like. As mentioned above,
A ceramic material, a photocurable resin, an organic binder, and an organic solvent or water are mixed and kneaded to form a solvent-based slip material or a water-based slip material. The method of mixing and kneading may be a conventionally used method, for example, a method using a ball mill. The slip material can be made thinner by, for example, a doctor blade method (knife coat method), a roll coat method, a printing method, or the like. In particular, a doctor can easily flatten the surface of the molded insulating layer after application. A blade method or the like is suitable. The viscosity is adjusted to a predetermined value according to the application method.

The drying is carried out using a batch drying oven or an in-line drying oven, and the drying temperature is desirably 100 ° C. or lower. Since rapid drying may cause cracks or the like on the surface, it is necessary to avoid rapid heating.
Next, the insulating layer molded body 10d is subjected to the following exposure treatment and cured. The process from the application of the slip material to the exposure process is repeated, and as shown in FIG.
A molded body 10 of the dielectric substrate 1 on which a to d are laminated is manufactured. Wiring layers, through holes,
Even when a via hole or the like needs to be provided, it can be easily formed by performing exposure and development processing as described later. Then, a conductive paste is applied to the surface of the molded body 10 of the dielectric substrate 1 to form a ground electrode conductive member 82.
Then, a conductive member (not shown) serving as a pad electrode is formed.

Next, the slip material is applied to the surface of the molded body 10 of the dielectric substrate 1 on which the ground electrode conductive member 82 is formed to form an insulating layer molded body 20d as shown in FIG. As shown in FIG. 5, a photo target 91 is placed on the insulating layer molded body 20d so that the area where the through hole is formed is shielded from light, and an ultra-high pressure mercury lamp (10 mW / cm
Exposure is performed using ² ) as a light source. Since the photocurable monomer contained in the slip material is a negative type, the photopolymerization reaction of the photocurable resin does not occur in the insulating layer molded body 20d in a region where the through hole is formed, and the through hole is not formed. A photopolymerization reaction occurs in the insulating layer molded body 20d other than the region where is formed. Here, the site where the photopolymerization reaction has occurred is called an insolubilized portion x, and the site where the photopolymerization reaction does not occur is called a solubilized portion y. In addition, the insulating layer molded body 20d having a thickness of about 100 μm is formed by an ultrahigh pressure mercury lamp (10 mW / cm ² ).
Is exposed for about 10 to 15 seconds to perform exposure.

The developing treatment is to remove the solubilized portion y of the insulating layer molded body 20d with a developing solution.
The development is performed by a spray method using trichloroethane. Thereafter, unnecessary debris and the like generated by the development of the insulating layer molded body 20d are completely removed by washing and drying processes, and as shown in FIG.
Then, an electrode through hole 93 is formed.

Next, as shown in FIG.
The inside is filled with a conductor paste by a screen printing method and dried. Further, a resin paste having good thermal decomposability containing a thermosetting or photocurable monomer is filled in the cavity through-hole 92, and the resin filling layer 94 is formed by thermosetting or exposure curing. As the resin paste constituting the resin filling layer 94, alkyl methacrylate or the like is used as a photocurable material, and an acrylate-based unsaturated polyester resin or the like can be used as a thermosetting material.

Thereafter, a slip material is further applied and the same process is repeated to form a laminated molded body 2 of the dielectric wall 2 on which the insulating layer molded bodies 20a to 20d are laminated as shown in FIG.
0 is formed. At this time, each of the insulating layer molded bodies 20a to 20
A resin filling layer 94 is filled in the cavity through hole 92 of d, and a ground electrode conductive member 96 constituting the vertical ground electrode 21 formed of a conductive material is formed in the electrode through hole 93. . Furthermore, the laminated molded body 2 of the dielectric wall 2
A conductive paste is applied to the upper end of the electrode 0 so as to be electrically connected to the vertical ground electrode 21 to form an electrode conductive member 95 for forming the electrode 61. Thus, a laminated molded article is obtained.

Next, the support substrate 9 is removed. Then, if necessary, the shape of the laminated molded product is adjusted by a press, or a divided groove is formed. Next, baking is performed. The firing includes a binder removing step and a main firing step. The binder removal step is performed in a temperature range of about 600 ° C. or less, and the organic binder contained in the conductive paste of the insulating layer molded bodies 10 a to 10 d and 20 a to 20 d, the resin filling layer 94, and the conductive members 82, 96 and 95. , A process of erasing the photo-curable resin, and the main baking step is performed at a peak temperature of 850 to 1050 ° C.
For example, it is a baking process of a peak at 900 ° C. for 30 minutes.

The conductive paste of the conductive members 82, 95 and 96 is made of a powder of at least one metal material of gold, silver, copper or an alloy thereof, a low-melting-point glass component, an organic binder and an organic solvent. A kneaded product is used. In particular, when the firing temperature is 850 to 1050 ° C,
As the metal material, a material having a relatively low melting point and a low resistance material is selected, and the low melting glass component is also considered in consideration of the sintering behavior with the insulating layer molded body (coated with a slip material and dried). The one whose yield point is around 700 ° C. is used.

In the insulating layer molded body thus fired,
Resin-filled layer 9 filled in cavity through-hole 92
4 disappears at the time of firing, and a cavity 51 is formed as shown in FIG. As shown in FIG.
On the main surface side of the dielectric substrate 1, it is also possible to form an electrode forming groove 32 continuous with the electrode forming groove 31, and to provide the vertical electrode 22 continuous with the vertical earth electrode 21. When forming the dielectric substrate 1, the electrode forming groove 32 and the vertical electrode 22 are exposed and developed at positions corresponding to the electrode forming groove 32 to form the electrode forming groove 32. The process of filling the conductive groove into the groove 32 can be repeated. In this case, the vertical ground electrodes 21 and 22 have a shape intersecting with the ground electrode 81 integrally.

A metal seal cap 71 is provided further above the dielectric wall 2. The seal cap 71 is provided so as to cover the upper part of each cavity 51, and is connected to the electrode 61 by a conductive adhesive. Circuit elements corresponding to each functional block are mounted in the area of the dielectric substrate 1 constituting each cavity 51 before the seal cap 71 is covered.

In the high-frequency module substrate of the present invention thus configured, even if electromagnetic waves are emitted from the circuit elements corresponding to the functional blocks mounted in each area, the vertical earth electrodes 21 and 22, the earth electrode 81 and the seal Since the electromagnetic wave is sealed in the cavity by the cap 71, it is possible to reduce mutual interference between the functional blocks. Although the example in which the laminated molded body 10 of the dielectric substrate 1 is formed on the support substrate 9 has been described, when a dielectric substrate created by a different method is used, this may be used as the support substrate. In this case, the step of removing the support substrate can be omitted. [Other Embodiments] The ground electrode 21 may be formed on the peripheral surface of the dielectric wall 2.

[0030]

According to the present invention, it is possible to confine electromagnetic waves emitted from circuit elements constituting each functional block to be mounted in each cavity, and to reduce mutual interference between the elements. A high-frequency module substrate excellent in miniaturization and mass productivity can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a high-frequency module substrate to which an embodiment of the present invention is applied.

FIG. 2 is a process chart showing the manufacturing method.

FIG. 3 is a process chart showing the manufacturing method.

FIG. 4 is a process chart showing the manufacturing method.

FIG. 5 is a process chart showing the manufacturing method.

FIG. 6 is a process chart showing the manufacturing method.

FIG. 7 is a process chart showing the manufacturing method.

FIG. 8 is a process chart showing the manufacturing method.

FIG. 9 is a process chart showing the manufacturing method.

FIG. 10 is a schematic configuration diagram of a longitudinal section.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric substrate 2 Dielectric wall 21 Vertical earth electrode 22 Vertical earth electrode 31 Electrode forming groove 32 Electrode forming groove 51 Cavity 61 Electrode 71 Seal cap 81 Ground electrode 91 Photo target 92 Cavity through hole 93 Electrode through hole 94 Resin filling layer 95 Electrode conductive member 96 Earth electrode conductive member

Claims (5)

[Claims] 1. A dielectric substrate on which a ceramic dielectric layer is laminated and on which a variety of circuit elements are mounted on a main surface, and the dielectric substrate for forming a plurality of cavities on the main surface of the dielectric substrate. A dielectric wall provided upright, a ground electrode provided on a main surface of the dielectric substrate, and a vertical end exposed from the upper end of the dielectric wall and connected to the ground electrode at a lower end. A high-frequency module substrate, comprising: a ground electrode; and a seal cap made of a conductive material that is connected to an upper end of the vertical ground electrode and covers an upper part of the plurality of cavities. 2. The high-frequency module substrate according to claim 1, wherein said vertical earth electrode has a middle portion embedded in said dielectric wall. 3. The high-frequency module substrate according to claim 1, wherein said vertical earth electrode has a lower end crossing said earth electrode and projecting into said dielectric substrate. 4. A step of: (a) applying a conductive paste to a main surface of a dielectric substrate to form pads and ground electrodes for mounting circuit elements; and (b) at least ceramic or glass ceramic. A step of applying a slip containing an insulating layer material and a photocurable resin on the main surface of the dielectric substrate, and further drying to form an insulating layer molded body; (c) an insulating layer molded body Is exposed and developed to form a through hole for a cavity and a through hole for an electrode, a conductive paste is filled in the through hole for an electrode, and a resin paste containing a photocurable or thermosetting monomer in the through hole for the cavity. And curing the resin paste by exposure or heating, (d) forming an insulating layer molded body by the slip, and repeating the step (c). (E) forming a vertical ground electrode that is electrically connected to the ground electrode and that has an upper end exposed from an upper portion of the multilayer molded body for the dielectric wall, while forming a laminated molded body for an electric body wall; Baking a laminate in which an insulating layer molded body is laminated on a body substrate at a predetermined temperature to disperse the resin paste filled in the through-holes for the cavity; and (f) the dielectric in the cavity. After mounting various circuit elements on the main surface of the substrate, a step of providing a seal cap made of a conductive material connected to the upper end of the vertical ground electrode and covering the plurality of cavities,
A method for manufacturing a high-frequency module substrate comprising: 5. A step of preparing a slip containing at least a ceramic or glass-ceramic insulating layer material and a photocurable resin; and (h) applying and drying the slip to form an insulating layer. Forming a molded body, (i) subjecting the insulating layer molded body to exposure treatment and curing the insulating layer molded body, and (j) the steps (h) and (i).
Forming a dielectric substrate by sequentially repeating the steps of
The method for manufacturing a high-frequency module substrate according to claim 4, further comprising: