JPH0653050A - Laminated chip inductor and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide the title chip inductor connecting to a through hole conductor without fail and the manufacturing method thereof. CONSTITUTION:When a conductor pattern 2 is transferred to a ceramic green sheet 1a whereon a through hole 3 is formed, the conductor pattern 2 is arranged to make the ends thereof pass over the though hole 3 for traversing the same 3. At this time, both ends of the conductor pattern 2 in the through hole 3 are closely bonded onto the ceramic sheet 1 while the part of the conductor pattern 2 is connected to one layer lower conductor pattern 2 in the through hole 3 without fail. Furthermore, when a transferred film is to be released, the open state of a coil conductor in the through hole 3 brought about in the conventional method can be avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated chip inductor in which through-hole conductors are securely connected and a method for manufacturing the same.

[0002]

2. Description of the Related Art A method of manufacturing a laminated chip inductor is as follows.
(Hereinafter, abbreviated as ") and a carrier, and then dried to form a ceramic green sheet. This ceramic green sheet is peeled off from the carrier and, for example, 100 mm
Prepare a green sheet cut into corners.

Since several hundreds of multilayer chip inductors are simultaneously formed on this green sheet, a sheet having through holes for connecting the conductor patterns for the coil depending on the number of chips and a sheet having no through holes are formed. And prepare. At this time, the formed through hole has a diameter slightly larger than the width of the conductor pattern.

Since the above-mentioned coil conductor pattern is a substantially U-shaped pattern and is produced by an ordinary screen printing method, a screen plate on which the pattern is formed is prepared. In addition, a PET film having substantially the same size as the green sheet is prepared.

When these are prepared, a substantially U-shaped conductor pattern in which a coil is formed by through-hole connection is printed on the PET film with a conductive paste such as Ag.

FIG. 6 is an exploded perspective view of stacking the above green sheets. In the stacking procedure, first, a predetermined number of green sheets without through holes are stacked as a protective sheet 1a on a stacking stand. . Then, on the uppermost sheet, there is a P printed coil conductor pattern.
The ET film is printed side down, pressure-bonded with PE
When the T film is peeled off, the conductor pattern 2 is transferred to the green sheet 1.

The green sheet 1 having the through holes 3 formed thereon is superposed thereon, and transferred so that the end portions of the substantially U-shaped conductor pattern are located inside the through holes. This is repeated a predetermined number of times, and finally the coiled conductor patterns are superposed and transferred to form a desired number of coil turns, and then a predetermined number of green sheets without through holes are laminated as the protective sheet 1a. Pressurized to form a laminated body in which the sheets are connected and integrated.

Next, the obtained laminated body is cut by a predetermined cut line 4 according to the individual chip size to form a chip element, which is fired and then external electrodes are provided to obtain a laminated chip inductor.

[0009]

SUMMARY OF THE INVENTION In the above conventional method,
When connecting the conductor pattern with a through hole, the end of the conductor pattern hangs down to the surface of the green sheet one layer below through the through hole, but there is little pressure in the through hole during transfer, so the PET film is peeled off. In doing so, as shown in the enlarged cross-sectional view of the through hole portion of FIG. 5, the conductor to be transferred in the through hole 3 has a stronger adhesive force with the PET film than the adhesive force with the green sheet.
There is a problem that the conductor pattern for a coil may be taken off as it is attached to the PET film 5 and may not be transferred, and the conductor pattern for a coil may be in an open state, so that the coil may not be formed.

Therefore, an object of the present invention is to provide a multilayer chip inductor in which through-hole conductors are reliably connected and a manufacturing method thereof.

[0011]

As a result of research to achieve the above object, the present inventor found that the main cause of the open state of the conductor pattern in the through hole is as shown in the sectional view of FIG. In view of the fact that the adhesive force between the conductor pattern and the transfer film is superior to the adhesive force between the conductor patterns, in the ceramic green sheets laminated adjacent to each other, the conductor pattern of the upper layer is In contrast to the conventional connection method in which the conductor pattern of the lower layer is depressed and is connected to the conductor pattern of the lower layer, if the end portions of the conductor pattern to be connected in the through hole portion are arranged so as to cross the diameter of the through hole, The present invention has been achieved by finding that the above is solved.

Therefore, according to the present invention, firstly, a coil conductor pattern provided inside a laminated body obtained by laminating ceramic green sheets made of a ceramic magnetic material is connected by through holes to form a coil. A multilayer chip inductor having a starting end and an ending end connected to different external electrodes, respectively, which are formed on the vertically adjacent green sheets and are connected to each other at through holes. And a laminated chip inductor characterized by being formed from a conductor that traverses the diameter of the through hole, and secondly, forming a through hole in a ceramic green sheet made of a ceramic magnetic material, The coil conductor is printed on the sheet and laminated on the laminated body obtained by laminating the coil conductor pattern. In a method of manufacturing a multilayer chip inductor in which a starting end and a terminating end are connected to different external electrodes, (a) a predetermined number of ceramic green sheets without through holes are stacked, ) On the uppermost sheet, a polyethylene terephthalate film, on which one of the conductor patterns of the coil is printed, is pressure-bonded with the printed surface facing down, the film is peeled off, and the pattern is transferred. The desired number of sheets is formed by stacking the ceramic green sheets on which are formed and transferring the polyethylene terephthalate film on which a substantially U-shaped conductor pattern is printed so that the ends of the pattern traverse the diameter of the through hole. Repeat every time, (d) the other side of the coil on the ceramic green sheet with through holes The present invention provides a method for manufacturing a multilayer chip inductor, which comprises the steps of: transferring lead conductor patterns and superimposing them, and (e) further laminating a predetermined number of ceramic green sheets having no through holes. .

[0013]

According to the present invention, the conductor pattern formed on the polyethylene terephthalate film is arranged such that the end of the conductor pattern crosses the through hole after printing and is transferred and pressure-bonded. The conductive paste is straddled continuously on both sides of the sandwich, and the conductive paste is pressure bonded to the ceramic sheet at both ends of the through hole.

Therefore, when peeling the film,
Since both ends of the conductive paste in the through hole are in close contact with the ceramic green sheet, it is not taken to the transfer film and the coil conductor in the through hole does not become open as described above. .

[0015]

Embodiment 1 FIG. 1 is a perspective view showing a conductor pattern connected to a through hole in this embodiment, FIG. 2 is an enlarged perspective view showing a through hole portion of FIG. 1, and FIG. It is sectional drawing which shows the condition which peels a transfer film after connecting, and it demonstrates below, referring these drawings.

First, as shown in FIG. 1, a predetermined number of ceramic green sheets in which through holes are not formed are laminated as a protective sheet 1a, and the coil lead conductor pattern is transferred to the uppermost sheet, and then the through holes 3 are formed. The ceramic green sheet 1 on which is formed is placed, and the conductor pattern formed on the transfer PET film is arranged so that the end portion of the conductor pattern crosses the through hole and pressure-bonded. Are transferred over the diameter of the through hole 3, and the end portion of the conductor pattern is formed at a position protruding from the through hole.

As is more apparent from the enlarged view of FIG. 2, the end portion of the conductor pattern 2 to be transferred is pressure-bonded to the green sheet 1 across the through hole 3 and at the same time, the green one layer below the through hole. It is closely connected to the conductor pattern formed on the sheet.

Further, as seen in the cross-sectional view of FIG. 3, when the PET film 5 is peeled off, the conductor pattern 2 does not have to be brought to the film.

After repeating the above operation to secure a desired number of turns, a predetermined number of green sheets without through holes were further laminated as a protective sheet and pressure-bonded to form an inductor.

Conventionally, the defect rate per layer was 1.14%, but it decreased to 0.12% by adopting the method of the present invention. In the product, the product yield when 20 layers were laminated was 79.5% by the conventional method and 97.6%.
Improved.

As can be seen from the above drawings, according to the present embodiment, since the end portions of the conductor patterns intersect, the coil conductor does not break even if the stacking position is slightly deviated. The effect is that it becomes easier.

[0022]

[Embodiment 2] As described in Embodiment 1, when a conductor pattern is transferred to a green sheet having a through hole formed thereon by using a transfer film, the end portion of the pattern is crimped so as to cross the through hole. According to the procedure of Example 1 except that the conductor pattern 2 transferred on the green sheet 1 and the conductor pattern transferred on the sheet one layer below are arranged as shown in the perspective view of FIG. A laminated inductor was constructed.

In this embodiment, since the coil conductor has no protruding portion, it is suitable for miniaturization of the chip, and has the effect of increasing the self-resonant frequency as compared with the case of the first embodiment.

[0024]

As described above, in the multilayer chip inductor manufactured by the method of the present invention, the conductor patterns in the through holes are in close contact with the ceramic sheet at both ends, so that the coil conductors can be easily connected. Therefore, disconnection of the coil is eliminated, which contributes to improvement of reliability.

[Brief description of drawings]

FIG. 1 is a perspective view showing a conductor pattern connected to a through hole in an embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing a through hole portion of FIG.

FIG. 3 is a cross-sectional view showing a state in which the transfer film is peeled off after the conductor pattern is through-hole connected by the method of the present invention.

FIG. 4 is a perspective view showing a conductor pattern to be through-hole connected in another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing an open defect of a through-hole conductor that is caused by peeling of a transfer film when a conductor pattern is through-hole connected by a conventional method.

FIG. 6 is a laminated exploded perspective view of a conventional laminated chip inductor.

[Explanation of symbols]

 1 Ceramic green sheet 1a Protective sheet 2 Conductor pattern 3 Through hole 4 Cut line 5 PET film

Claims (2)

[Claims] 1. A coil is formed by connecting a coil conductor pattern provided in a laminated body obtained by laminating ceramic green sheets made of a ceramic magnetic material by through holes, and a coil has a start end and an end that are different from each other. A multilayer chip inductor connected to the external electrodes of the above-mentioned green sheets, which are respectively formed on the vertically adjacent green sheets, and the end portions of a pair of conductor patterns connected at the through-hole portions are A multilayer chip inductor formed by a conductor that extends across a diameter. 2. A coil conductor is internally provided in a laminated body obtained by forming through holes in a ceramic green sheet made of a ceramic magnetic material, printing a coil conductor pattern on the sheet, and laminating the coil conductor pattern. In a method of manufacturing a multilayer chip inductor in which and are connected to different external electrodes, (a) a predetermined number of ceramic green sheets without through holes are stacked, and (b) a coil on the uppermost sheet. The polyethylene terephthalate film on which one of the lead-out conductor patterns is printed is pressure-bonded with the printed surface facing down, the film is peeled off and the pattern is transferred, and (c) the ceramic green sheets having through holes are stacked, A polyethylene terephthalate film printed with a substantially U-shaped conductor pattern is The operation of transferring so that the end of the pattern crosses the diameter of the through hole is repeated for each desired number of sheets, and (d) the other conductor pattern of the coil is transferred to the ceramic green sheet in which the through hole is formed. And (e) further including respective steps of stacking a predetermined number of ceramic green sheets having no through holes formed therein.