JPH07101830B2 - Ceramic filter manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a small ceramic filter used for communication equipment or the like.

(Summary of the Invention) The present invention is a method for manufacturing a ceramic filter using a piezoelectric ceramic substrate, wherein a predetermined filter electrode film is provided at a plurality of positions of the rod-shaped piezoelectric ceramic substrate integrally formed with the rod-shaped part. A pattern is formed, and a perforated protective substrate having the same shape as the perforated piezoelectric ceramic substrate is bonded and integrated to the perforated piezoelectric ceramic substrate to form a laminated substrate, and thin film technology is applied to both ends of the laminated rod-shaped portion of the laminated substrate. By forming the end electrode film by cutting and separating into individual ceramic filters, the process can be shortened and the productivity can be improved. Further, in the obtained ceramic filter, end electrode films connected to the filter electrode film pattern are formed at both ends of a laminated structure formed by integrally bonding a piezoelectric ceramic substrate having a filter electrode film pattern formed thereon and a protective plate. With this structure, the size can be reduced, and the product dimensional accuracy and the product strength can be improved.

(Prior Art) FIG. 10 and FIG.
Shown in Figure 11. In these figures, 50 is a piezoelectric ceramic substrate on which a predetermined filter electrode film pattern is formed, 51A, 51
B is a cover, and the cover is formed of an insulating resin so that at least the cavity portions 53A and 53B are provided on the opposing surfaces corresponding to both surfaces of the vibrating region that is a portion that vibrates when the piezoelectric ceramic substrate 50 operates. 52A and 52B are resin sealing coats that cover both surfaces of the piezoelectric ceramic substrate 50 provided with the cover 51. The covers 51A and 51B are piezoelectric ceramic substrates 50.
A first layer is formed by printing and curing an insulating resin on each of the vibration areas on both surfaces and the partial surface excluding a specific electrode position, and cavities 53A and 53B facing the vibration area are formed on the upper surface of the first layer. As described above, a two-layer structure is formed with a second layer in which an insulating resin is applied by printing and cured. The resin sealing coat 52A, 52B
Is also provided by applying an insulating resin by printing and curing.

Next, in order to reinforce the strength of the main body portion including the piezoelectric ceramic plate 50, the covers 51A and 51B, and the sealing coats 52A and 52B, a glass epoxy plate 56 having a ground electrode 54 is fixed to the lower surface of the main body portion with an adhesive 57. Then, the laminated structure 58 is obtained. Then, as shown in FIG. 11, the metal caps 59A and 59B as the end electrode material are used.
Are attached to both ends of the laminated structure 58. This metal cap
59A and 59B are mounted by elastically sandwiching both side ends of the laminated structure 58, and are fixed to the electrodes 55A and 55B on the upper surface of the filter electrode film pattern formed on the piezoelectric ceramic plate 50 by soldering, respectively, and electrically. Connected to form an end electrode. At the same time, the ground electrode 54 of the glass epoxy substrate 56 and the electrode 55C on the lower surface of the filter electrode film pattern are also connected by soldering.

(Problems to be solved by the invention) By the way, the above-mentioned conventional ceramic filter, by applying the cover 51A, 51B for providing the cavity and the sealing coat 52A, 52B, by applying an insulating resin by printing and curing it. Since the number of layers to be laminated is large, the number of manufacturing steps is large. Further, since the metal caps 59A and 59B are used for the end electrode material, it takes time and effort to form and mount the metal caps, resulting in high cost, which is not suitable for rationalization of manufacturing. In addition, as the ceramic filter becomes smaller, the handling becomes more troublesome in the process of manufacturing and mounting the metal cap, and the productivity and the dimensional accuracy of the product must be improved.

In view of the above points, the present invention provides a method of manufacturing a ceramic filter that can be downsized and can improve product dimensional accuracy and product strength, and that can simplify manufacturing processes, streamline manufacturing processes, and improve mass productivity. The purpose is to do.

(Means for Solving the Problems) In order to achieve the above object, a method for manufacturing a ceramic filter of the present invention is a method in which a rod-shaped portion is integrally formed with a predetermined number of portions of the rod-shaped piezoelectric ceramic substrate. The step of forming the filter electrode film pattern and the perforated protective substrate in which the rod-shaped portion is integrally formed and the cavity portion is formed on the facing surface corresponding to at least the vibration area of the piezoelectric ceramic substrate are bonded to the perforated piezoelectric ceramic substrate. A step of integrally forming a laminated substrate, a step of forming end electrode films by thin film technology at both ends of a laminated rod-shaped portion in which the rod-shaped portion of the piezoelectric ceramic substrate and the rod-shaped portion of the protective substrate are laminated,
And a step of cutting and separating the laminated substrate into a plurality of pieces so as to have one filter electrode film pattern.

(Operation) In the method of manufacturing a ceramic filter of the present invention, a piezoelectric ceramic substrate having a hole is integrally formed with a rod-shaped portion, and is treated as one plate at the time of manufacturing (substrate processing method) to achieve lamination. In each process such as process and end electrode forming process, simultaneous processing of multiple ceramic filters is possible without using a buret, etc., making the process line (unification of transport between processes) and mass production easy. Becomes
It is possible to reduce the manufacturing cost and the manufacturing time.

Thin film technology such as sputtering, ion plating, P-CVD, etc. is applied to the laminated rod part of a laminated substrate in which a metal cap is not used for the end electrode material and a perforated protective substrate of the same shape as the perforated piezoelectric ceramic substrate is overlaid. Since the end electrode film of the metal thin film is formed by deposition, it is possible to easily control the thickness of the end electrode film with high accuracy, simplify the end electrode formation process and enable mass production by simultaneous film formation. Therefore, the material cost and the manufacturing process can be reduced, and the product dimensional accuracy and the mounting rate can be improved, and the size and the thickness can be sufficiently reduced.

Further, when the piezoelectric ceramic substrate has a laminated structure in which both surfaces are sandwiched and fixed by protective substrates such as alumina having a hollow portion, the bending strength of the ceramic filter can be improved and the hollow portion can be surely secured.

(Example) Hereinafter, an example of a method for manufacturing a ceramic filter according to the present invention will be described with reference to the drawings.

FIG. 1 is a process drawing for explaining a manufacturing process of a ceramic filter. First, as shown in FIG. 2, a plurality of slit holes 11 are punched or laser-processed in parallel at predetermined intervals in an unfired piezoelectric ceramics sheet substrate to form a large number of rod-shaped portions 12 between the parallel slit holes. then,
After sintering the piezoelectric ceramic sheet substrate, a required polarization treatment is performed to form a polarized piezoelectric ceramic substrate (PZT) 1 with holes.

In the electrode forming step 2, the polarized piezoelectric ceramic substrate 1 with holes is provided with predetermined filter electrode film patterns at a plurality of positions on both surfaces of each rod-shaped portion 12. The filter electrode film pattern has a double-sided structure, and as shown in FIG. 3, a predetermined front side filter electrode film pattern 14 is provided on the front side of each rod 12 and a predetermined back side filter electrode corresponding to the front side is provided on the back side. The film patterns 15 are formed by thin film techniques such as sputtering. The electrode films 14A and 14B in the front side filter electrode pattern 14 are also continuously formed on the side surfaces of the rod-shaped portion 12, respectively. It should be noted that the vibrating region (where the filter action is performed) corresponding to one filter electrode film pattern of the rod-shaped portion 12 is a region surrounded by a dotted line P.

On the other hand, as shown in FIG. 4, at least cavities 23, 3 are formed on the opposing surfaces corresponding to the vibration regions (dotted line P in FIG. 3) provided for each filter electrode film pattern of the perforated piezoelectric ceramic substrate 1.
Prepare perforated alumina protective substrates 20 and 30 having 3. These perforated alumina protective substrates 20 and 30 have the same planar shape as the perforated piezoelectric ceramic substrate 1.

As shown in FIG. 4, the protective substrate 20 on the front side is formed by forming a plurality of cavities 23 in parallel at predetermined intervals by pressure molding or the like on an unsintered alumina sheet substrate, and slits on both sides of the cavity 23. Holes 21 are punched in parallel at a predetermined interval by laser processing or laser processing, and rod-like portions 22 having a large number of hollow portions 23 are formed.
And is sintered to have.

Similarly, the back side protective substrate 30 is formed by forming a plurality of cavities 33 and electrode holes 35 in parallel at predetermined intervals by pressure molding or the like on an unsintered alumina sheet substrate, as shown in FIG.
Slit holes 31 are formed on both sides of the cavity 33 and the electrode hole 35 in parallel at a predetermined interval by punching or laser processing,
It is sintered so as to have a rod-shaped portion 32 having a large number of hollow portions 33 and electrode holes 35.

The cavities 23 and 33 are
It is provided in order to smoothly operate and protect the vibration in the vibration region of the perforated piezoelectric ceramic substrate 1.

In the laminating step 3, perforated alumina protective substrates 20 and 30 having cavities 23 and 33 are bonded and integrated on both surfaces of the perforated piezoelectric ceramic substrate 1 to form a perforated laminated substrate 40. That is, as shown in FIG. 4, an adhesive 43 is printed on a predetermined bonding portion on the front side of the perforated piezoelectric ceramic substrate 1 on which the filter electrode film pattern has been formed, and the vibration region of the piezoelectric ceramic substrate 1 is formed thereon. The front side protective substrate 20 having the hollow portion 23 is pressure-bonded. And the back side is also adhesive
43 is printed, and the back side protective substrate 30 has a cavity 33 corresponding to the vibration region and an electrode hole 35 corresponding to the back side electrode film pattern 15.
Is pressure-bonded to form a laminated substrate 40 having a slit hole 41 and a laminated rod-like portion 42 as shown in FIG.

Then, in the end electrode forming step 4, as shown in FIG. 6, the metal thin films 16A and 16B constituting the lower layer portion of the end electrode film are formed.
Is formed in the state of the laminated substrate 40 by sputtering, that is, the metal thin films 16A and 16B are formed so as to surround both end portions of each laminated rod-shaped portion 42 in a substantially U shape, and also penetrate the electrode hole 35. The metal thin film 16 is connected to the back side electrode film pattern 15.
Form C.

The metal thin films 16A and 16B are electrically connected to the end portions of the electrode films 14A and 14B in the front filter electrode film pattern 14 shown in FIG. 3, and the metal thin film 16C is an electrode of the back filter electrode film pattern. They are electrically connected to the holes 35 and each have a two-layer structure. For example, the lower layer is a NiCr, Ti or Cr sputtered film having good adhesion to ceramics, and the upper layer is a resistive Cu sputtered film. When forming the thin film, the unnecessary portions on both sides of the laminated substrate 40 and the side surfaces of the laminated rod-shaped portion 42 are masked in advance.

Further, in the end electrode plating step 5, plating is performed on the substrate thin films 16A, 16B and 16C of each laminated rod-shaped portion 42 with the laminated substrate 40 as it is, and as shown in FIG. 7, substrate plated films 17A, 17B,
17C is deposited on the substrate thin films 16A, 16B and 16C to form the end electrode films 18A and 18B and the terminal electrode film 18C as shown in FIG. Here, the metal plating films 17A, 17B, 17C have a two-layer structure, and the lower layer directly deposited on the metal thin films 16A, 16B, 16C has a solder resistance (solder diffusion prevention and solder heat resistance) Ni. The plating film and the upper layer are Pb-Sn or Sn plating films with good solder adhesion. The plating may be electrolytic (wet) plating or electroless plating.

Then, in a cutting step 6, the lamination is performed along a cutting margin (also shown in FIGS. 3 and 6) indicated by a chain line X in FIG. 7 so as to have one filter electrode film pattern. The rod-shaped portion 42 is cut with a dicing saw or divided by slit grooves to have one filter electrode film pattern inside as shown in FIGS. 8 and 9, and end electrode films 18A and 18B connected to this. Thus, one ceramic filter having the terminal electrode film 18C is obtained.

As shown in the exploded perspective view of FIG. 8, each ceramic filter includes a piezoelectric ceramic substrate 45 on which a front filter electrode film pattern 14 and a back electrode film pattern 15 are formed,
An upper protective plate 46 made of alumina having a cavity 23 formed on at least the opposing surface corresponding to the vibration area of the piezoelectric ceramic substrate.
And a lower protective plate 47 made of alumina in which the cavity 33 is formed in the same manner.
And the back end filter electrode film pattern 1 having end electrode films 18A and 18B connected to the filter electrode film pattern at both ends of a laminated structure 48 formed by adhering and integrating
It has a terminal electrode film 18C connected to 5.

After cutting into individual ceramic filters, washing and drying are performed as necessary to obtain products.

Although the front and back filter electrode film patterns 14 and 15 are formed by a thin film technique such as sputtering in the electrode forming step 2 in the above embodiment, they may be formed by a thick film technique such as printing by printing a conductor paste.

In the end electrode film forming step 4, the metal thin films 16A, 16B,
Although 16C is formed by a two-layer sputtered film, a three-layer structure may be used in which the lowermost layer is a NiCr sputtered film, the intermediate layer is a CuNi sputtered film, and the upper layer is a Cu sputtered film. Further, the structure may be made of only one Cu sputtered film.

Also, instead of sputtering, ion plating, P-
The metal thin film may be formed by CVD or the like.

(Effect of the Invention) As described above, the method for manufacturing a ceramic filter of the present invention uses the perforated piezoelectric ceramic substrate integrally formed with the rod-shaped portion and the perforated protective substrate having the same shape (the substrate processing method). ), It can be processed as one plate at the time of manufacturing, and a large number of ceramic filters can be processed at the same time without using a pallet or the like. Therefore, it becomes easy to make the process lines (unification of conveyance between processes) and mass production, and it is possible to reduce the manufacturing cost range and the manufacturing time.

Further, since a metal cap is not used for the end electrode material, the troublesome work of mounting the metal cap can be omitted, and the workability can be improved. Furthermore, since the end electrode film by thin film technology is applied to the laminated rod-shaped portion of the laminated substrate in which the protective substrate is overlaid on the piezoelectric ceramic substrate, and the laminated substrate is cut into chips, the material cost and the manufacturing process are reduced, Variations in product dimensions can be reduced, and further miniaturization and thinning can be supported.

[Brief description of drawings]

FIG. 1 is a process diagram showing a manufacturing process of an embodiment of the present invention, and FIG.
FIG. 4 is a perspective view showing a polarized piezoelectric ceramic substrate, FIG. 3 is a partial perspective view showing an electrode forming process, FIG. 4 is a partially exploded perspective view showing a laminating process, and FIG. 5 is a perspective view showing a laminated substrate in the same process. FIG. 6 is a partial perspective view showing an end electrode forming step, FIG. 7 is a partial perspective view showing an end electrode plating step,
8 is an exploded perspective view showing the structure of the ceramic filter after cutting, FIG. 9 is a perspective view showing the finished ceramic filter after the cutting process, and FIG. 10 is an exploded view showing the structure of an example of a conventional ceramic filter. A perspective view and FIG. 11 are front views of the same. 1 ... Polarized piezoelectric ceramic substrate, 2 ... Electrode forming step,
3 ... Laminating process, 4 ... End electrode forming process, 5 ... End electrode plating process, 6 ... Cutting process, 11, 21, 31, 41 ... Slit hole, 1
2,22,32 ... Rod-shaped part, 14 ... Front side filter electrode film pattern, 1
5 ... Back side filter electrode film pattern, 16A, 16B, 16C ... Metal thin film, 17A, 17B, 17C ... Metal plating film, 18A, 18B ... End electrode film, 18C ... Terminal electrode film, 20 ... Front side protective substrate, 30 ... Back side protective substrate, 23, 33 ... Hollow part, 35 ... Electrode hole, 40 ... Laminated substrate, 4
2 ... Laminated bar, 43 ... Adhesive, 45 ... Piezoelectric ceramic substrate, 46, 47 ... Protective plate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliography flat 2-5929 (JP, U) flat 1-74623 (JP, U) flat 58-76223 (JP, U)

Claims (1)

[Claims] 1. A predetermined filter electrode film pattern is formed at a plurality of positions of the rod-shaped piezoelectric ceramic substrate integrally formed with the rod-shaped portion, and the rod-shaped portion is integrally formed and at least the piezoelectric ceramic substrate is formed. A perforated protective substrate having a cavity formed on the opposing surface corresponding to the vibration region is bonded and integrated with the perforated piezoelectric ceramic substrate to form a laminated substrate, and the rod-shaped portion of the piezoelectric ceramic substrate and the rod-shaped portion of the protective substrate are formed. Of the ceramic filter, wherein end electrode films are formed on both ends of the laminated rod-shaped part in which is laminated by thin film technology, and then the laminated substrate is cut and separated into a plurality of pieces so as to have one filter electrode film pattern. Production method.