JPH02161710A - Manufacture of coil parts - Google Patents

Abstract

PURPOSE:To obtain a coil whose mechanical strength, interlayer insulation and humidity resistance are excellent by a method wherein interlaminar parts are densely unified in a body by winding a green sheet of ceramic insulating material around a green rod whose shrinkage factor at the time of baking is smaller than the green sheet, and baking the sheet. CONSTITUTION:A green sheet 2 composed of oxide ceramic fine powder and organic binder is formed on a Mylar film 1, and a coil 3 is drawn by using Pt conductive paste. A green rod 5 is arranged perpendicularly to the longitudinal direction of the coil, and is bonded to the terminal edge 6 of a green sheet 4. While the sheet 2 is exfoliated from the film 1 by using a flat plate 7, a winding terminal end is bonded. A roll 8 is cut at a position 9, and baking is performed at an optimum condition, thereby obtaining an element body 10. Ag paste is printed on both ends 11, 12 of the element body 10, and external electrodes 13, 14 are formed. Leads 15, 16 are fixed, and a device is completed. By the effect of fastening pressure caused by the difference of shrinkage factors between the green sheet 4 and the rod, the interlaminar parts are densely unified in a body.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a coil component, and an object thereof is to provide a method suitable for manufacturing a small and highly reliable coil component.

In recent years, various proposals have been made regarding high-density packaging of electronic components with the aim of downsizing electronic circuits and improving their reliability. One such method is to embed components in a printed circuit board to make the circuit smaller and flat, while also allowing more space for external components. However, such a mounting method has not yet been fully put into practical use. This is thought to be due to the fact that a suitable shape and performance for an embedded chip component has not been obtained sufficiently.

Taking coil components as an example, the main requirements for a chip for embedding are that the size is equivalent to the thickness of a printed circuit board (most current printed circuit boards are 1.6 m thick).
m), and the width is at most 5 mm or less, considering the conductor of the printed circuit board.
When considering embedding, the ideal shape is a cylinder or disk that can be easily inserted into the through hole of the printed circuit board without considering directionality. It is desirable to have a structure in which one electrode is located on one surface of the circuit board, and the other electrode is located on the other surface.

There are no existing small coil components that meet these requirements.For example, axial lead type high frequency coils have a shape that is easy to embed, but they have axial leads and the size is similar to the thickness of the printed circuit board.・Not suitable for embedding in circuit boards.

The present invention eliminates these drawbacks and provides a method capable of producing small, highly reliable coil components having a diameter of up to 5+n+n and a thickness of 1.6 mm. That is, a flexible 11 green sheet containing a ceramic insulator material printed with a conductive paste for a coil is wound onto a green rod of a ceramic insulator material having a shrinkage rate smaller than the shrinkage rate in firing of this green sheet. A cylindrical molded body is formed and fired under the usual firing conditions for ceramic insulators.1. Further, an external electrode is provided on the end face of the obtained sintered body, and a lead wire is provided on the external electrode as required, thereby obtaining a coil component.

The coil component obtained in this way has an extremely tight lamination between the green sheets, between the green sheet and the coil, and between the green sheet and the green rod, and is made of high-density ceramic sintered with an integral color. Concretions are obtained;
bogus! II: Does not generate feelings.

As a result, a small coil component with excellent mechanical strength, two-layer insulation, and moisture resistance can be obtained. Further, this coil component has a cylindrical or disc shape, and can be easily embedded in the temporary through hole 7'j4 of the glint circuit I. In addition, after implantation, the electrodes are placed on the same flat plate as the printed circuit board, and there are no hollow holes.
It can also be easily connected to the conductor of a printed circuit board using conductive adhesive or the like. At this time, unlike conventional coil parts, there is no need to form lead terminals in advance, and after embedding the circuit board, the electrodes can be attached for connection. Upper culm l-6 has great advantages. Of course, even if a roughened electrode is formed, the effects of the present invention will not be lost.

The reasons for the above effects of the present invention and 1-1.

This is caused by the shrinkage rate of the wound green: >-1- which is more human-friendly than the core of the green, which is the center of the shaft. A force similar to that of applying a certain amount of pressure is generated on the wound sheet, and this appears as a tightening effect. This method of winding and tightening that takes advantage of the difference in firing shrinkage rate is an extremely useful method for coil parts that are wound and fired with Inirami, Kugreen-1, which has weak mechanical strength. , -4 In other words, not only is it possible to omit the winding and pressing operations, but also the pressure naturally generated during firing is so uniform that it cannot be obtained by applying force from the outside. It is possible to obtain high-quality fired products that were previously unavailable.

Next, an embodiment of the method for manufacturing a coil component according to the present invention will be described with reference to the drawings.

Green sheets of ceramic insulator material are made by known methods. 1 millivinyl butyral resin was added as a machine binder to fine powder of oxide ceramic having the known +A Il+ LIt composition. Also plastic +
Add di-n-butyl phthalate as 4 and 2, and mix δ uniformly with C with a solvent in a ball mill to make a slip, and coat this with a known method such as a knife coater, pipe coater, reverse roll coater, or screen printing. Appropriate mold release treatment is applied to the surface as shown in Figure 1 (
7 Mylar Fill J, forming a skin 1 pattern on Heath 1+,
A green sheet 2 having a predetermined lJ size is obtained by dry smoking.

Next, on this green sheet 2, platinum and platinum-palladium are placed.

A conductive paste made of palladium or silver-palladium as a conductive material is applied to one plate having multiple patterns.
Then, the coil 3 as shown in Fig. 2 is formed.
A green sheet 4 is produced.

The length of this coil 3 is the total length of the coil wound into one coil component. Next, this green sheet 4 is placed on a flat table, and a green rod 5, which will be described later, is glued to the end edge 6 of the green sheet 4 with a suitable adhesive at right angles to the longitudinal direction of the coil. Figure 3 shows these relationships. Then, as shown in Fig. 4, the green rod 5 is pressed from above by the flat plate 7 and rolled in the longitudinal direction of the coil, and the green sheet 2 is rolled up while being peeled off from the Mylar film base l, and the final end is fixed with an appropriate adhesive. Fix it to obtain a rod-shaped rolled product. Next, the rolled product 8 is cut at the position of the broken line 9 as shown in the cross-sectional view of FIG. 5 to obtain a cylindrical molded body. This was fired under the optimum firing conditions for the green sheet, and the coil component body lO shown in Fig. 6 was produced.
get. Furthermore, as shown in FIG. 7, a silver conductive paste is applied to both end surfaces 11.12 of this element body 10 and baked to form external electrodes 13.14. If necessary, connect lead wires 15.16 to external electrodes 13.14 as shown in FIG.
Connect with solder etc. to make a coil component.

FIG. 9 is a sectional view showing an example of the coil component body 10 being pressed and mounted on a printed circuit board. Reference numeral 17 denotes a printed circuit board, which has a through hole 18 having a diameter approximately equal to the diameter of the cylindrical coil component.

A coil component element body 10 having approximately the same thickness as the printed circuit board 17 is inserted into this through hole 18 so that both sides of the printed circuit board 17 and both end surfaces of the coil component element body 10 are on the same plane. insert.

Next, the coil 3 exposed on both end faces of the coil component element body lO
By electrically connecting the conductors 19 and 20 on the printed circuit board 17 with conductive adhesives 21 and 22, the coil component embedded circuit board is completed. Thereby, the conductive adhesives 21 and 22 also serve as electrodes.

The shrinkage rate during firing of the green rod in the present invention must be smaller than the shrinkage rate of the green sheet when fired under the optimum firing conditions under which the green sheet is fired.The shrinkage rate during firing of the green rod is: When the firing conditions are constant, they are determined by the physical and chemical properties of the ceramic powder constituting it, the characteristics of the organic binder, the blending amounts of these constituent materials, and the green density. Specifically, it is desirable that the green sheet be made of ceramic and an organic binder having the same composition as the green sheet. In this case, either use a particle size larger than the particle size of the ceramic material used for the green sheet, or use a smaller amount of organic binder than the amount of organic binder in the green sheet, or pressurize the green rod. This can be achieved by increasing the density by, for example, applying a heat treatment to the green rod at a temperature lower than the decomposition temperature of the organic binder.

In addition, as another method, the shrinkage rate of the green rod can be made smaller than that of the green sheet by mixing other ceramic materials with the green rod or changing the component ratio. That is, a ceramic material is used for the green rod, which sinters slightly more slowly than the ceramic material for the green sheet under the same firing conditions.

Green rods are produced by kneading ceramic powders and organic binders selected from those mentioned above using a roll machine, a milling machine, etc., and then extruding the kneaded product into a rod shape from a nozzle using heat and pressure. It will be done. The cross-sectional shape does not particularly need to be circular, and the effects of the present invention can be achieved even if the cross-sectional shape is oval or flat. Moreover, the green rod may not be an extruded product but may be a rod-shaped product obtained by winding a green sheet.

As described above, the present invention involves winding a green sheet of ceramic insulating material around a green rod having a smaller shrinkage rate than the shrinkage rate during firing of the green sheet, and then firing it. During firing, the coil parts obtained are extremely densely integrated between the layers due to the tightening pressure due to the difference in retention rate between the green sheets, and are free from delamination and cracking. , therefore, n-machine.

This makes it possible to create small coil parts with excellent mechanical strength, interlayer insulation, and thermal resistance.

Further, according to the present invention, it is possible to obtain a small-sized coil component with high yield and good mass productivity.

[Brief explanation of the drawing]

Figures 1 to 8 are diagrams for explaining each step of the method for manufacturing a coil component according to the present invention, and Figure 9 is a cross-sectional view showing a state in which the coil component obtained by the present invention is mounted on a printed circuit board. It is. 1... Mylar film heath, 2...
・Green sheet, 3... Coil, 4...
...green sheet with a coil, 5...green rod, 6...terminal edge of green sheet,
7... Flat plate, 8... Rolled product, 9.
... Cutting position, 10 ... Coil component body, 11.12 ... End face, 13.14 ...
・External electrode, 15.16...Lead wire, 17.
...Princess I/Circuit board, 18...Through hole, 192122...Conductive adhesive. Name of agent For patent attorney Shigetaka Awano and 1 other person 20...Conductor, 1 Figure 2 Figure 4, □ 3 Figure 4 Collection 9 Figure

Claims (4)

[Claims] (1) A flexible green sheet containing a ceramic insulator material on which a plurality of conductive pastes for coils are printed in parallel and straight lines, and the above-mentioned conductive pastes for connecting external electrodes are printed on both ends of each in opposite directions. A cylindrical molded body is obtained by winding the green sheet onto a green rod containing a ceramic insulating material having a shrinkage rate smaller than that of the green sheet during firing, and the cylindrical molded body is coated with the conductive paste for external electrode connection. A method for manufacturing a coil component, which comprises cutting the cylindrical molded body at the end, firing the cylindrical molded body, and forming electrodes on both end faces of the obtained sintered body. (2) The method for manufacturing a coil component according to claim 1, wherein the conductive material of the conductive paste for coils is platinum, palladium, platinum-palladium, or silver-palladium. (3) The method for manufacturing a coil component according to claim 1, wherein the ceramic insulator material is an oxide ceramic. (4) The method for manufacturing a coil component according to claim 1, wherein the green rod is made of a ceramic insulating material having the same composition as the green sheet and an organic binder.