JPH07105302B2 - Chip inductor manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a small chip inductor used in an electronic device or the like.

Regarding

(Summary of the Invention) The present invention is a method for manufacturing a chip inductor suitable for miniaturization, in which an inductive conductor film pattern is formed on a substrate surface excluding an outer surface and a slit is formed so that a rod-shaped portion is integrally formed. By firing an unfired laminated substrate with holes, forming end electrodes at both ends of the rod-shaped portion of the laminated substrate after firing, and then cutting and separating into individual chip inductors, continuous process and productivity Can be improved. In addition, the obtained chip inductor has a structure in which end electrodes composed of a metal thin film and a metal plating film are provided at both ends of a ferrite chip on which an inductive conductor film pattern is formed. It is possible to improve accuracy and reduce material costs.

(Prior Art) An example of the structure of a conventional chip inductor is shown in FIG. 12 as a first conventional example. In this case, as the chip inductor, an example of microchip beads in which the number of turns of the inductive conductor pattern is less than 1 is shown. In this figure, reference numeral 50 denotes a ferrite chip, which has two through holes 51A and 51B. The through holes 51A, 51B are respectively connected to the end electrodes 53A, 53B provided at both ends of the ferrite chip through conductor patterns 52A, 52B at one opening end face, and by the conductor pattern 52C at the other opening end face. Connected to each other.

This microchip bead is manufactured by firing a chip-shaped unfired ferrite chip provided with through holes in advance, and the through holes 51A, 51B and conductor patterns 52A, 52B, 52C, and further the end electrodes 53A, 53A are Ag. -The end electrodes 53A, 53 are formed by printing, applying and baking a conductor paste such as Pd material.
After electroplating, the surface except the end electrode portion is coated with an insulating coat.

Further, FIG. 13 is a second conventional example and shows an example of a wide band choke in which the number of turns of the inductive conductor pattern is one or more as a chip inductor. In this figure, the ferrite chip 55 is provided with six through holes 56A to 56F, which are conductor patterns 57 on both end faces.
The electrodes A to 57G are connected to each other or to the end electrodes 58A and 58B at both ends of the ferrite chip. That is, the conductor pattern 57A includes the end electrode 58A and the through hole.
56A is connected and conductor pattern 57B, 57C, 57D, 57E, 57F
Forms a coil that connects each through hole as shown in the figure and turns in a vertical plane. Then, the through hole 56F and the end electrode 58B are connected via the conductor pattern 57G, and a wide band choke that turns in a vertical plane is configured by the above configuration.

The wide band choke according to the second conventional example having the above configuration is manufactured by the same manufacturing method as that of the first conventional example.

(Problems to be Solved by the Invention) By the way, as in the conventional chip inductor shown in FIGS. 12 and 13, a long through hole is provided so as to penetrate from one surface of the ferrite chip single body to the other surface. In the case of a structure in which a conductor pattern is used for connection, the connection between the through holes is not easy when the size is small, and the provision of the through holes requires the thickness of the ferrite chip. Therefore, as in the wide band choke structure of the second conventional example. When the number of turns is large, the thickness is further increased, and there is a drawback that miniaturization becomes difficult.

Also on the manufacturing method, through holes are formed in an unfired ferrite chip molded into a chip shape and then fired, and through holes and conductor patterns by printing and baking are applied to each fired chip.
Since the end electrodes are formed (bulk processing), separate chips are processed in each process, and there is a concern that the processing will be troublesome when forming the end electrodes and transfer between each process. Takes time. Further, in bulk processing, it is difficult to automate the appearance selection of products and it is difficult to make the process continuous.

Moreover, when the end electrodes are made of a thick film by coating and baking Ag-Pd material etc. as in the past, it is difficult to control the thickness, and there is a tendency that the outer dimensions are likely to vary, and the material cost is high. There was a drawback.

In addition, Japanese Patent Publication No. 60-50331 is a method of manufacturing an inductance element in which an inductance element is formed by a printing method, but since the magnetic permeability and volume of the insulating layer that insulates each metal pattern from each other cannot be increased, the obtained inductance There is a limit to the value.

In view of the above points, the present invention can reduce the size of the chip inductor and improve the product dimensional accuracy, can reduce the material cost, and can simplify and rationalize the manufacturing process and improve mass productivity. An object is to provide a method for manufacturing a chip inductor.

(Means for Solving the Problems) In order to achieve the above-mentioned object, a method for manufacturing a chip inductor of the present invention is such that the unfired ferrite is formed by laminating a plurality of unfired ferrite sheet substrates and excluding a surface to be an outer surface. -The unbaked laminated substrate formed by forming an inductive conductor film pattern on any one of the substrate surfaces of the sheet substrate and forming slit holes so that the rod-shaped portions are integrally formed is fired, and the laminated substrate after firing is baked. After forming a metal thin film by a thin film technique so as to surround the end of the rod-shaped portion in a substantially U-shape, forming a metal plating film on the metal thin film to form an end electrode, and cutting the rod-shaped portion into a plurality of pieces. To separate.

(Operation) In the manufacturing method according to the present invention, a slit is formed so that the rod-shaped portion is integrally formed in a laminate of a plurality of unfired ferrite sheet substrates provided with a conductor film pattern except the substrate surface which is the outer surface. By using a laminated substrate in which holes are formed and fired and integrated, and processing is performed as one substrate in which a plurality of ferrite chips are connected in each process (substrate processing method) In the appearance selection process, etc., multiple chip inductors can be processed simultaneously without using a pallet, etc., making process lines (unification of transfer between processes) and mass production easy, reducing manufacturing costs and manufacturing. The required time can be shortened.

Further, without using a conductor paste such as Ag-Pb for the end electrode material, the lower electrode of the end electrode is formed on the rod portion of the laminated substrate after firing by a thin film technique such as sputtering, ion plating, or P-CVD. Since the metal thin film is deposited and the metal plating film is further provided, the thickness of the end electrodes can be easily controlled with high accuracy, and the end electrode film forming process can be simplified and mass production by simultaneous film formation can be performed. It is possible to reduce the material cost and manufacturing process, and improve the product dimensional accuracy and mounting rate.
Furthermore, it can be made smaller and thinner.

(Example) Hereinafter, an example of a chip inductor and a manufacturing method thereof according to the present invention will be described with reference to the drawings.

FIG. 1 is a process diagram for explaining a manufacturing process of microchip beads as a chip inductor. First, accept the unfired ferrite sheet substrate 1 shown in FIG.
In the conductor film pattern printing step 2, a plurality of predetermined inductive conductor film patterns 11 are provided in parallel on one substrate surface of the ferrite sheet substrate 1 by printing a conductor paste as shown in FIG. The conductor film pattern 11 is half-turned in the plane of the substrate as shown in the drawing, and both ends thereof are formed in a projecting shape so as to be connected to the end electrodes later. That is, in this case, since the number of turns is less than one, a microchip bead is formed.

Next, in a laminating step 3, as shown in FIG. 4, ferrite sheet substrates 1B and 1C having no conductor film are laminated so as to sandwich the ferrite sheet substrate 1A provided with the conductor film pattern 11. Then, in the next stacking (pressing) step 4, a uniform pressure treatment is carried out to produce an unfired laminated substrate having a three-layer structure.

After that, in the slit forming step 5, a plurality of slit holes 12 are punched or laser-processed in parallel at predetermined intervals in the unfired laminated substrate as shown in FIG. 5, and a large number of rod-shaped portions 13 are formed between the parallel slit holes. By doing
An unfired perforated laminated substrate 14 is produced. The positions of the slit holes 12 on each unfired ferrite sheet substrate are shown by imaginary lines in FIGS. 2 to 4.

Then, by sintering the perforated laminated substrate 14 in the firing step 6, the laminated and slit-hole-processed sheet substrates 1A, 1B, 1C are integrated, and a plurality of inductive conductor film patterns 11 are provided inside. A perforated ferrite substrate 15 having the rod-shaped portion 13 is obtained. At this time, V to U-shaped grooves, which serve as a cutting allowance when the chips are separated in a later step, may be formed in advance in the stacking step 4 or the slit forming step 5 and baked. It should be noted that both ends of the inductive conductor film pattern 11 are exposed at the end faces of the rod-shaped portion 13 by providing slit holes 12.

Then, in the end electrode film forming step 7, as shown in FIG. 6, the metal thin films 16A and 16B forming the lower layer part of the end electrode are formed by sputtering in the state of the perforated ferrite substrate 15, that is, Metal thin films 16A and 16B are formed so as to surround both ends of the rod-shaped portion 13 in a substantially U-shape. Metal thin film here 1
6A and 16B are electrically connected to both ends facing the slit hole 12 of the inductive conductor film pattern 11 shown in FIG. 3, and each has a two-layer structure. For example, the lower layer is adhesive to ferrite. A good sputtered film of NiCr, Ti or Cr, and a Cu sputtered film with a low resistance in the upper layer. At the time of forming the thin film, masking processing is performed in advance on both surfaces of the perforated ferrite substrate 15 and unnecessary portions on the side surfaces of the rod-shaped portion 13.

Further, in the end electrode plating step 8, the metal thin films 16A and 16B of each rod 13 are plated with the perforated ferrite substrate 15 as it is, and as shown in FIG.
17B is deposited on the metal thin films 16A, 16B to form end electrodes 18A, 18B.
Make up B. Here, the metal plating films 17A and 17B have a two-layer structure, and the lower layer directly deposited on the metal thin films 16A and 16B has solder resistance (prevention of solder diffusion and solder heat resistance).
Ni plating film, Pb-Sn or Sn whose upper layer has good solder adhesion
It is a plated film. The plating may be electrolytic (wet) plating or electroless plating.

After that, the perforated ferrite substrate 15 is placed on the adhesive sheet, and in the cutting step 9, the cutting allowance (third part) indicated by the one-dot chain line X in FIG. 7 so as to have one inductive conductor film pattern 11 (third part). (Also shown in FIGS. 6 and 6), the rod-shaped portion 13 is cut and separated by a dicing saw or the like along
As shown in Fig. 9 and Fig. 9, one inductive conductor film pattern is provided inside.
One microchip bead having 11 and having end electrodes 18A, 18B connected to it is obtained. However, the two-dimensional pressure-sensitive adhesive sheet does not change the mutual planar positional relationship even after cutting, and in this state, in the next appearance selection step 10, image selection is automatically performed using image processing. Those that are judged to have a poor appearance by image processing are selectively removed. Products that are judged to be good in appearance are products.

8 and 9 show a finished microchip bead 20 obtained by the above-mentioned manufacturing method, and as shown in the exploded perspective view of FIG. 8, have a half-turn inductive conductor film pattern 11. End electrodes 18A, 18B connected to the inductive conductor film pattern on both ends of a ferrite chip 22 formed by laminating chip ferrite plates 21B and 21C having no conductor film on both sides of a chip ferrite plate 21A and firing and integrating them. It has a structure that has. However, as apparent from the perspective view of FIG. 9, the end electrodes 18A and 18B are the ferrite chips 2
Both ends of 2 are enclosed in a substantially U-shape, and the side surface of the ferrite chip 22 is not covered. This is a great advantage as well as reduction of variations in product dimensions due to the use of a combination of a metal thin film and a metal plating film by the thin film technology as the end electrodes 18A and 18B.

10 and 11 show another embodiment of the present invention,
In the above-described embodiment, the inductive conductor film pattern is provided on one substrate surface of the unfired ferrite sheet substrate, but in this case, the inductive conductor film is formed on each substrate surface of the plurality of unfired ferrite sheet substrates. A pattern is formed (excluding the substrate surface that is the outer surface of the laminated substrate), and the dielectric film patterns are laminated so that they are connected to each other through holes.
In the chip inductor, a wide band choke having one or more turns is constructed.

The manufacturing process of the embodiment of this wide band choke is the same as that of the process chart of FIG. 1, but in the conductor film pattern printing step 2, as shown in FIG. 10, for example, three ferrite sheet substrates 31A, 31B, Predetermined inductive conductor film patterns 32A, 32B, 32C are formed on one of the substrate surfaces of 31C.
Further, through holes 33 are formed in the ferrite sheet substrates 31A, 31B, 31C at positions where the conductor film patterns are connected to each other so as to form a coil that turns one or more times (see also FIG. 11). It is indicated by the same symbol.).

In the following laminating step 3 and stacking step 4, laminating ferrite sheet substrates 31D, 31E having no conductor film on both surfaces of the three ferrite sheet substrates 31A, 31B, 31C having the above-mentioned inductive conductor film pattern. Thus, a 5-layer unbaked laminated substrate is produced. At this time, the respective conductor film patterns are connected to each other through the through holes 33 to form a coil having one or more turns. Then, in the slit forming step 5, slit holes 12 are formed and then fired to form a perforated ferrite substrate.

Then, a product is obtained through each step as in the above embodiment. FIG. 11 shows an exploded perspective view of the finished product of the wide band choke 30 obtained by this manufacturing method. As can be seen from the figure, the inductive conductor film pattern forming a coil having one or more turns. 32A, 32B, 32C and through hole 33
3-layer chip-shaped ferrite plates 34A, 34B, 34C having
And, it has a structure having end electrodes 35A, 35B connected to the inductive conductor film patterns 32A, 32C at both ends of a ferrite chip formed by laminating and firing and integrating ferrite plates 34D and 34E without conductor films. .

In the case of the embodiment described with reference to FIGS. 10 and 11 above, the case where three layers of inductive conductor film patterns are laminated and the number of turns of the coil is one and a half is shown. A pattern having a different shape may be formed, or the number of stacked layers may be increased or decreased.

Further, in the above embodiment, the connection between the inductive conductor film and the end electrode may be made by a through hole.

Further, in the end electrode film forming step 7, the metal thin film was formed of two layers of sputtered film, but the bottom layer was formed of NiCr sputtered film,
A three-layer structure in which the intermediate layer is a CuNi sputtered film and the upper layer is a Cu sputtered film may be used. 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.

(Effects of the Invention) As described above, according to the method for manufacturing a chip inductor according to the present invention, a slit hole is formed in a laminate of a plurality of unfired ferrite substrates so that the rod-shaped portion is integrally formed. By using a laminated substrate that is integrated by firing (substrate processing method), it is possible to process multiple chips as one substrate at the time of manufacturing, and it is possible to process multiple chip inductors simultaneously. It is possible without using Therefore, the process can be made into a line (unification of conveyance between processes) and mass production can be facilitated, the appearance selection can be automated by image processing, and the manufacturing cost and the manufacturing required time can be shortened.

Further, the laminated rod-shaped portion of the laminated substrate is provided with an end electrode film by a thin film technique, and the laminated substrate is cut into chips, so that it is possible to reduce the material cost and the manufacturing process and reduce the variation in product dimensions. Furthermore, it can be made smaller and thinner.

[Brief description of drawings]

FIG. 1 is a process diagram showing a manufacturing process of an embodiment of the present invention, and FIG.
The figure shows a perspective view of an unfired ferrite sheet substrate, the third
FIG. 4 is a partial perspective view showing a conductive film pattern printing process, FIG. 4 is a partially exploded perspective view showing a laminating process, FIG. 5 is a perspective view showing a slit forming process, and FIG. 6 is an end electrode film forming process. Partial perspective view, FIG. 7 is a partial perspective view showing the end electrode plating step, FIG. 8 is an exploded perspective view showing the structure of the microchip beads as the chip inductor after cutting, and FIG. 9 is the completion of the microchip beads. FIG. 10 is a perspective view showing the product, FIG. 10 is a partially exploded perspective view showing a laminating step in another embodiment of the present invention, FIG. 11 is an exploded perspective view showing the structure of the wide band choke after cutting, and FIG. FIG. 13 is a perspective view showing an example of the configuration of a conventional chip inductor, and FIG. 13 is a perspective view showing the configuration of another conventional example. 1 ... Unfired ferrite sheet substrate, 2 ... Conductor film pattern printing process, 3 ... Laminating process, 4 ... Stacking process, 5 ... Slit forming process, 6 ... Firing process, 7 ...
Edge electrode deposition process, 8 ... Edge electrode plating process, 9 ...
Cutting process, 10 ... Appearance selection process, 11,32A, 32B, 32C ... Inductive conductor film pattern, 12 ... Slit hole, 13 ... Rod portion, 14 ... Perforated laminated substrate, 15 ... Perforated Ferrite substrate, 16A, 16B …… Metal thin film, 17A, 17B …… Metal plating film,
18A, 18B, 35A, 35B …… End electrode, 22 …… Ferrite chip, 33 …… Through hole.

Continuation of the front page (56) Reference JP-A-59-103321 (JP, A) JP-A-55-145333 (JP, A) Actually open 1-17912 (JP, U) Actually open 58-116204 (JP , U)

Claims (2)

[Claims] 1. An unsintered ferrite sheet, which is obtained by laminating a plurality of unsintered ferrite sheet substrates and excluding an outer surface.
The unfired laminated substrate formed by forming an inductive conductor film pattern on one of the substrate surfaces of the sheet substrate and forming slit holes so that the rod-shaped portions are integrally formed is fired, and the rod of the laminated substrate after firing is fired. After forming a metal thin film by thin film technology so as to surround the upper end in a substantially U-shape, forming a metal plating film on the metal thin film to form an end electrode, cutting the rod-shaped portion into a plurality of pieces A method of manufacturing a chip inductor, comprising: 2. The method for manufacturing a chip inductor according to claim 1, wherein the inductive conductor film patterns are formed on a plurality of substrate surfaces and are connected to each other by through holes.