JPH09266402A - Manufacture of conductor imbeded dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the electric resistance of the imbeded conductor, to allow gaps to be hardly caused in the vicinity of the conductor part at lamination and to avoid production of exfoliation at baking by punching a primary board made of a dielectric material into a conductor shape to be imbeded and filling in conductor paste to punched holes. SOLUTION: A required number of dielectric sheets 30 are laminated and pressed lightly. Then a primary board 32 is obtained. The primary board 32 are punched into a conductor shape to be imbeded. Furthermore, a conductor paste 36 is put on an upper face of the primary board 32 and the paste is filled in punched holes 34 formed on the primary board 32. Then an uppermost layer of dielectric sheet 30a is exfoliated. Then the conductor imbeded primary board 38 is obtained. Since the laminated dielectric sheets 30 are lightly pressed, only the uppermost layer of dielectric sheet 30a is easily exfoliated. Then the conductor paste 36 adhered to the upper face of the dielectric sheet 30a is also removed at the same time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a dielectric filter having a structure in which an inner conductor is provided inside a dielectric chip and an outer conductor and an input / output electrode are provided outside. More specifically, according to the present invention, a primary substrate made of a dielectric material is punched into various conductor shapes to be embedded, the punched holes are filled with a conductive paste, and the obtained primary substrates are laminated and integrated to form a conductor-embedded conductor. Type dielectric filter. The dielectric filter manufactured by this method is used, for example, in various mobile communication devices used in the microwave band.

[0002]

2. Description of the Related Art There are many types of microwave filters that use dielectric materials. One of them is a type in which the resonator is composed of a strip line. For example, in the case of a quarter wavelength resonator, a stripline type resonator internal conductor is provided inside the dielectric material, one end of which is an open end, and the other end is an outer conductor of the outer surface of the dielectric material ( Ground conductor). Basically, a plurality of in-resonator conductors set to have a length that is an odd multiple of 1/4 of the resonance wavelength are arranged in parallel inside the dielectric material at a predetermined interval so as to have an appropriate degree of coupling. As a result, a bandpass filter characteristic is obtained.

[0003] With the recent miniaturization of communication equipment, dielectric filters have been required to be further miniaturized, and in order to cope with this, a laminated structure has been partially adopted. This is because a dielectric sheet with a large number of unsintered dielectric sheets (green sheets) laminated and the necessary internal conductor pattern printed is sandwiched internally, and the outermost layer has an outer conductor pattern. In this method, a body sheet is arranged, pressure-bonded and integrated, a necessary conductive material is attached to the side surface of the chip to form an outer conductor on the side surface, and sintering is performed.

An example of a two-stage interdigital type laminated dielectric filter is shown in FIG. In addition to a simple dielectric sheet (dielectric sheet not having a conductor pattern) 10, a dielectric sheet 12 having a resonator conductor pattern printed on its surface by screen printing using a conductive paste
And a dielectric sheet 14 having an outer conductor pattern printed on the entire surface
Then, the dielectric sheet 16 on which both the H-shaped outer conductor pattern 15a and the two rectangular input / output electrode patterns 15b insulated from it are prepared. Here, the conductor pattern in the resonator is a pattern in which two linear conductor patterns are arranged in parallel.

A dielectric sheet 12 on which an in-resonator conductor pattern is printed is arranged in the center, and simple dielectric sheets 1 are provided on both sides.
0 is laminated in the required number, the dielectric sheet 14 with the outer conductor pattern formed on the uppermost surface, and the dielectric sheet 16 with the outer conductor pattern and the input / output electrode pattern formed on the lowermost layer are heated and pressed. By press-bonding to integrate. The lowermost dielectric sheet 16 is laminated so that the outer conductor pattern and the input / output electrode pattern appear on the outer surface (lower surface in FIG. 12). After that, a conductive paste is applied to the side surface of the chip to form side conductors that will become the outer conductor 20 and the input / output electrodes 22, and the firing is performed, whereby the laminated dielectric filter 24 is obtained.

Usually, in such a manufacturing method, a dielectric sheet having a large area is used so that a large number of pieces can be taken, and printing is carried out so that necessary patterns are regularly arranged in the vertical and horizontal directions, and pressure bonding and integration are performed. After that, a method is adopted in which the chips are cut vertically and horizontally and separated into individual chips.

The conductor pattern is printed by screen-printing on a dielectric sheet using a silver-based conductive paste. Therefore, the conductor pattern is placed on the dielectric sheet. The dielectric sheet is a sheet obtained by bonding dielectric ceramic powder for microwaves with an organic binder and has a thickness of about several tens of μm. The conductor pattern formed thereon is as thick as possible in order to reduce electric resistance, and has a thickness of about ten and several tens of μm.
A large number of dielectric sheets are laminated in a predetermined order so as to sandwich the dielectric sheet having such a conductor pattern printed therein, and they are pressed and integrated by a heat press.

[0008]

As described above, the dielectric sheet is in a non-fired state (state in which the ceramic powder is bound with the organic binder) and is as thin as several tens of μm, so that the conductive sheet When printing is performed using the paste, the phenomenon called sheet attack occurs due to the vehicle contained in the conductive paste. Sheet attack is a phenomenon in which a vehicle is deformed so as to be wrinkled by the adhesion of a vehicle. When the sheets thus deformed are laminated and integrated, the inner conductor pattern and the outer conductor pattern are displaced from each other, resulting in large variations in characteristics. The only way to prevent sheet attack is to use a conductive paste containing a vehicle that is compatible with the dielectric sheet. However, in general, a conductive paste having a good compatibility has a property of being dried rapidly, and if such a conductive paste is used, it will be dried if printed 2-3 times. Therefore, it is necessary to clean the screen and perform the next printing, and the workability is extremely poor. In other words, in the prior art,
There is a large limitation on the conductive paste that can be used, and there is a problem that a conductive paste containing a vehicle with good printing workability cannot be used.

Further, although a process of laminating dielectric sheets printed with conductor patterns and pressurizing and integrating them is performed, a gap is apt to occur between the dielectric sheets in the vicinity of the end portions of the conductor patterns. This is because the dielectric sheet with unevenness on which a comparatively thick conductor pattern is printed and which is placed on the surface overlaps with the flat dielectric sheet with nothing printed on it, so the pressure is not uniform during pressurization. This is because it is difficult to apply sufficient pressure near the end of the conductor pattern. This not only causes unevenness in the laminated block, but when such a gap occurs, the gap is an air layer, so the relative dielectric constant is much smaller than that of the surrounding dielectric material, and the cause of deterioration of Q Becomes Further, the gap is a state in which the dielectric sheets are not sufficiently pressure-bonded to each other, which causes separation during firing.

Further, in the prior art, it is necessary to cut the stacked blocks vertically and horizontally into chips, and then print the outer conductor on the side surfaces. As a result, work efficiency is low, it takes time, and pattern breakage easily occurs at the side corners.

The object of the present invention is to make the conductors to be embedded inside various kinds thicker, so that the electric resistance of the conductors can be remarkably reduced, and moreover, gaps are less likely to occur in the vicinity of the conductor portions during lamination, and therefore the characteristics are good. It is an object of the present invention to provide a method for manufacturing a dielectric filter that does not peel off during firing. Another object of the present invention is to make it possible to simultaneously form the side conductors only by stacking layers, and therefore, it is possible to greatly simplify the process, such as eliminating the need to apply the conductive paste after cutting, and to improve the production efficiency. A method of manufacturing a body filter is provided.

[0012]

The present invention is a method for producing a dielectric filter having a structure in which an inner conductor is provided inside a dielectric and an outer conductor and an input / output electrode are provided outside. A feature of the present invention is that a primary substrate made of a dielectric material is punched into various conductor shapes to be embedded, the punching holes are filled with a conductive paste, and the conductor-embedded primary substrates are laminated and integrated, and the conductor is embedded by firing. A method for manufacturing a dielectric filter.

Here, the primary substrate may be composed of one dielectric sheet, but it is usually desirable to laminate a plurality of dielectric sheets. For example, several to several tens of dielectric sheets having a thickness of several tens of μm are laminated to form a primary substrate. The most preferable configuration is a first primary substrate in which an outer conductor and an input / output electrode are embedded, a second primary substrate in which side conductors for the input / output electrode and the outer conductor are embedded, and an input / output electrode together with a resonator inner conductor. And a third primary substrate in which side conductors for the outer conductor are embedded, a fourth primary substrate in which side conductors for the outer conductor are embedded, and a fifth primary substrate in which the outer conductor is embedded, in that order. Laminated and integrated with, and cut at the position of the side conductor to make a chip,
There is a firing method.

When a single dielectric sheet is used as the primary substrate, a plurality of conductor-embedded primary substrates having the same shape are laminated to increase the conductor thickness and sufficiently reduce the electric resistance. Can also be configured.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A primary substrate composed of a plurality of dielectric sheets is punched out according to various conductor shapes to be buried, and the punching holes are filled with a conductive paste to form a sufficiently thick inner conductor. It becomes possible to do.
Also, since the side conductors have almost the same thickness as the primary substrate,
Electrical connection between the upper and lower primary substrates becomes possible. Therefore, by laminating and integrating the primary substrates including the conductors of a predetermined shape, the side surface conductors are electrically connected at that point, so it is only necessary to fire after cutting the laminated block. It is not necessary to apply the conductive paste on the side surface in the process. Further, since the primary substrate is a state in which a plurality of dielectric sheets are laminated, punching holes if punched at a time,
As a result, the conductors filling the punched holes are not displaced, and a highly accurate dielectric filter can be obtained.

[0016]

EXAMPLE FIG. 1 is a flow sheet showing an example of a method for manufacturing a dielectric filter according to the present invention. The dielectric sheet is a sheet obtained by binding dielectric ceramic powder for microwaves with an organic binder and has a thickness of 50 to 80.
It is about μm. Laminate a plurality of these (several to dozens),
A primary substrate is manufactured by lightly pressing. This is the primary stacking process. The thickness of the primary substrate is about 450 to 720 μm. This primary substrate is punched (punching step) according to various conductor shapes to be buried, and the punching hole is filled with a conductive paste (conductive paste filling step) to produce a conductor-embedded primary substrate. In the conductive paste filling step, the conductive paste is applied using the uppermost dielectric sheet of the dielectric sheet laminate as a mask, and then the uppermost dielectric sheet is peeled off. As a result, the punching holes of the dielectric sheet laminated body of the second layer or lower can be filled with the conductive paste cleanly. Of course, the film may be placed on the upper surface of the primary substrate, the primary substrate may be punched out together with the film, the conductive paste may be applied onto the film, and then the film may be peeled off. As the mask film, a thin film having good peelability and toughness, such as a polyester film (trade name: Mylar), is desirable. Next, various conductor-embedded primary substrates are laminated in a predetermined order (main lamination process). Then, heat and pressure are applied to completely bond the whole to form a laminated block. This laminated block is cut at the position of the side surface conductors to be separated into individual chips, and then baked to obtain a finished product (dielectric filter).

FIG. 2 is a process explanatory view showing a punching / filling process. As described above, the required number of dielectric sheets 30 are laminated (see A) and lightly pressed. This gives the primary substrate. Next, as shown in B, the primary substrate 32
Are punched out according to various conductor shapes to be buried. The punched holes are shown at 34. Here, in order to make the drawings easy to understand, a simple strip-shaped punching hole 34 is described as an example, but the shape of the punching hole has no particular meaning. Further, as shown in C, a conductive paste 36 is laid on the upper surface of the primary substrate 32, and the punched holes 34 formed in the primary substrate 32 are filled (painted) with the conductive paste 36. Then, as shown in D, the uppermost dielectric sheet 30a is peeled off. As a result, the conductor-embedded primary substrate 38 is obtained. Since the laminated dielectric sheets are only lightly pressure-bonded, only the uppermost dielectric sheet can be easily peeled off. At the same time, the conductive paste attached to the upper surface of the uppermost dielectric sheet can be removed. Therefore, only the conductive paste embedded in the punched holes remains on the obtained primary substrate. In this state, the thickness of the buried conductor is almost the same as the thickness of the primary substrate.

FIG. 3 is an explanatory view showing an example of the primary substrate. The first primary substrate 40a is punched into a shape corresponding to the outer conductor and the input / output electrode, and the punched hole 42a serves as the H-shaped outer conductor portion 45 and the rectangular input / output electrode located in the recess. This is a structure in which the conductor 44a including the portion 46 is embedded. In FIG. 3, in order to make the explanation easy to understand,
The primary substrate and the conductor are drawn separately, and only two conductors are drawn. However, in reality, as shown in FIG.
A large number of conductors 44a are regularly arranged vertically and horizontally on one primary substrate 40a.

5 to 8 are explanatory views showing other examples of the primary substrate. The second primary substrate 40b shown in FIG. 5 has punched holes 42 corresponding to side conductors for the input / output electrodes and outer conductors.
b is formed, and a side surface conductor 44b to be a part 47 of the input / output electrode and a part 48 of the outer conductor is embedded therein. The third primary substrate 40c shown in FIG. 6 is formed with punched holes 42c corresponding to the side conductors for the input / output electrodes and the outer conductor together with the intra-cavity conductor, and the intra-cavity conductor 49 and one of the input / output electrodes are formed therein. Side portion 44 which is the part 51 and a part 50 of the outer conductor
It is a structure in which c is embedded. FIG. 7 shows a fourth primary substrate 40d
In this structure, a punching hole 42d having a shape corresponding to the side conductor for the outer conductor is formed, and a side conductor 44d, which is a part 53 of the outer conductor, is embedded in the punching hole 42d. FIG. 8 shows a fifth primary substrate 40e, which has a structure in which a conductor portion 44e, which is a part 54 of the outer conductor, is embedded in a punching hole 42e shaped to be the outer conductor on the entire surface.

The first primary substrate 40a to the fifth primary substrate 40e are laminated in that order, heated and pressed, and completely pressure-bonded to form a laminated block. Then, the laminated block is cut vertically and horizontally at the position of the side surface conductor to form a chip. In order to make it easier to understand the chipped state, FIG. 9 shows an exploded perspective view of a portion corresponding to each primary substrate. The symbol a corresponds to the first primary substrate, and the symbol b corresponds to the second primary substrate. Hereinafter, symbols c to e correspond to the third primary substrate to the fifth primary substrate, respectively. Thus, the vertical and horizontal cutting is performed at a position where the side surface conductor is exposed.

A dielectric filter is obtained by firing after chip formation. A perspective view of the completed dielectric filter is shown in FIG. In FIG. 10, A is a perspective view with the mounting surface side (input / output electrode formation surface) facing upward, and B
On the contrary, it is a perspective view with the mounting surface facing downward.

The above description is for a two-stage interdigital filter. That is, the resonator pattern is as shown in FIG.
As shown in A of FIG. 1, it has two in-resonator conductors arranged in parallel, and one in-resonator conductor and the other in-resonator conductor are open ends (electrically connected to the side conductors. In this configuration, the non-exposed end) and the short-circuited end (the end electrically connected to the side surface conductor) are alternately arranged in the opposite direction. On the other hand, the present invention can be applied to the case of manufacturing a combline type dielectric filter having a configuration in which the open end and the short-circuited end are arranged in the same direction as shown in FIG. 11B. For that purpose, the position and shape of the side surface conductor which is a part of the outer conductor may be appropriately changed.

It goes without saying that the present invention can be applied to the production of a dielectric filter having one or more stages. The present invention can also be applied to a structure in which a load capacitance conductor is arranged as an inner conductor in the vicinity of the in-resonator conductor inside the dielectric.

In the present invention, the conductive paste filled in the punched hole is supported by the side wall of the punched hole.
Therefore, the thickness (sidewall area) of the primary substrate is required according to the property of the conductive paste and the filling amount. In order to increase the contact area, it is preferable that the primary substrate is thick to some extent, but depending on the properties of the conductive paste (such as viscosity), the shape of punched holes, and the filling amount, a single dielectric sheet constitutes the primary substrate. It is also possible to do so. When the thickness of the conductor is required, a structure in which a plurality of the same primary substrates are laminated is also possible. However, it is usually desirable to form the primary substrate by laminating a plurality of dielectric sheets, form punched holes in the primary substrate, and fill the conductive paste with the conductive paste.

[0025]

As described above, the present invention is a method of forming a conductor-embedded primary substrate by filling a punching hole formed in the primary substrate with a conductive paste and stacking the conductor-embedded primary substrate. Since the thickness can be increased and the electric resistance is reduced, the Q is improved, the insertion loss is reduced, and the filter characteristics can be improved.

Further, according to the method of the present invention, since the conductor is embedded in the inside of the primary substrate, no gap is created between the primary substrates during the stacking, and therefore a uniform pressure can be applied during the pressure bonding and integration. it can. The generation of the gap means the existence of the air layer, and the dielectric constant is lowered, so that the characteristic (Q) is lowered, but the present invention does not cause such a problem. Further, there is no fear of peeling during firing.

Further, in the present invention, since the primary substrate having a certain thickness is used, the pattern displacement due to the bending of the dielectric sheet does not occur and the problem of the sheet attack due to the conductive paste does not occur. In other words, since the dielectric sheet is not deformed, compatibility with the conductive paste does not have to be taken into consideration, it can be easily manufactured using the optimum conductive paste, and the degree of freedom in selecting materials is expanded. In particular, in a method in which a plurality of dielectric sheets are laminated and punched out, the conductor forming accuracy becomes very good, and variations in characteristics can be suppressed.

Further, in the present invention, since the side conductors are continuous during the main lamination, it is not necessary to print the side outer conductors after cutting into chips. In the present invention, since the formation of all conductors is completed when the chips are cut vertically and horizontally to form chips, the working efficiency is significantly improved. Further, unlike the printing, since the conductor is thick, it is possible to prevent the occurrence of pattern breakage at the side corners.

[Brief description of drawings]

FIG. 1 is a process explanatory view showing an example of a process of manufacturing a dielectric filter according to the present invention.

FIG. 2 is an explanatory view showing a punching process of a primary substrate and a conductive paste filling process.

FIG. 3 is an explanatory diagram of a first primary substrate.

FIG. 4 is an explanatory diagram showing an arrangement state of conductors on a primary substrate.

FIG. 5 is an explanatory diagram of a second primary substrate.

FIG. 6 is an explanatory diagram of a third primary substrate.

FIG. 7 is an explanatory diagram of a fourth primary substrate.

FIG. 8 is an explanatory diagram of a fifth primary substrate.

FIG. 9 is an exploded perspective view showing an example of a conductor-embedded dielectric filter.

FIG. 10 is a perspective view of a completed product showing an example of a conductor-embedded dielectric filter.

FIG. 11 is an explanatory diagram showing an in-resonator conductor and a side conductor serving as an input / output electrode and an outer conductor.

FIG. 12 is an explanatory view showing the structure of a conventional laminated dielectric filter.

[Explanation of symbols]

 30 Dielectric Sheet 32 Primary Substrate 34 Punching Hole 36 Conductive Paste 38 Conductor-Embedded Primary Substrate

Claims (4)

[Claims] 1. An internal conductor is provided inside a dielectric chip,
In a method of manufacturing a dielectric filter having a structure in which an outer conductor and an input / output electrode are provided on the outer side, a primary substrate made of a dielectric material is punched into various conductor shapes to be embedded, and the punched holes are filled with a conductive paste. 2. A method of manufacturing a conductor-embedded dielectric filter, comprising: integrally laminating and firing the conductor-embedded primary substrate. 2. The method for manufacturing a conductor-embedded dielectric filter according to claim 1, wherein the primary substrate is formed by laminating several to several tens of dielectric sheets having a thickness of several tens of μm. 3. A first primary substrate in which an outer conductor and an input / output electrode are embedded, a second primary substrate in which side conductors for the input / output electrode and the outer conductor are embedded, and an input / output electrode together with a resonator inner conductor. A third primary substrate in which a side conductor for the outer conductor is embedded, a fourth primary substrate in which a side conductor for the outer conductor is embedded, and a fifth primary substrate in which the outer conductor is embedded, in that order. Laminated and integrated with, and cut at the position of the side conductor to make a chip,
The method for manufacturing a conductor-embedded dielectric filter according to claim 2, which comprises firing. 4. The conductor-embedded dielectric filter according to claim 1, wherein the primary substrate is made of a single dielectric sheet, and the conductor thickness is increased by laminating a plurality of conductor-embedded primary substrates having the same shape. Method.