JP2015177091A - Method of manufacturing multilayer inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a multilayer inductor which allows for easy production of a low DC resistance product having a large coil area, by using a general-purpose printing screen.SOLUTION: When forming a coil, going around spirally while overlapping in the lamination direction, in a magnetic material 11 by creating the printing parts 1-8, where an electrically insulating magnetic material 11 is printed around conductor patterns 10a-10d forming partial shapes A, B, C, D of a coil, by screen printing, sequentially laminating and pressure bonding the printing parts 1-8, and sequentially connecting the conductor patterns 10a-10d in the lamination direction, two printing parts 1(2), 3(4), 5(6), 7(8) having the same partial shapes A, B, C, D of a coil are sequentially laminated and pressure bonded.

Description

  The present invention relates to a method for manufacturing a multilayer inductor in which a coil is formed in a magnetic material by laminating a magnetic layer and a conductive pattern by screen printing.

  In recent years, with the demand for miniaturization and thinning of power circuit components, multilayer chip inductors have been developed and put into practical use as transformers and choke coils used in power circuits such as DC-DC converters.

  In such a multilayer inductor, an electrically insulating magnetic layer and a conductor pattern are alternately laminated, and the conductor pattern is sequentially connected in the laminating direction, so that the spiral is formed in a magnetic material while being superimposed in the laminating direction. A coil that circulates around the coil is formed, and both ends of the coil are respectively drawn out to the outer surface of the multilayer chip through lead conductors. Here, ferrite is used as the magnetic material, and the magnetic layer and the conductor pattern are formed by screen printing and sequentially stacked.

  FIG. 13 is a diagram for explaining a general method for manufacturing a multilayer inductor by screen printing. First, as shown in FIG. 13A, an Ag paste is used on a PET sheet 20 using a printing screen. While printing the partial shape of a coil, the printing part 21 which printed the ferrite around it is formed.

  Next, as shown in FIG. 13B, after the printed part 22 obtained in this way is pressure-bonded and transferred onto the ferrite block 23, as shown in FIG. 13C, a PET sheet 20 is obtained. Remove only. Then, the above-described multilayer inductor is manufactured by sequentially repeating the above steps and sequentially laminating a plurality of printing sections 21 on the printing section 21 from which the sheet 20 has been peeled off, followed by degreasing and firing.

  By the way, in the mobile market which requires miniaturization in recent years, the value of a current flowing through an inductor is increasing in accordance with an increase in switching frequency of a power supply used and an improvement in processing performance.

  In order to cope with this, it is conceivable to increase the thickness of the coil to make it a low DC resistance product. However, in recent years, printing screens are thinner in the direction of increasing accuracy, contrary to thick coating. is there. For this reason, there is no printing screen that can be used for printing a thick coil, and it is difficult to manufacture a required low DC resistance multilayer inductor.

JP-A-8-264364

  The present invention has been made in view of the above circumstances, and provides a method for manufacturing a multilayer inductor that can easily manufacture a low DC resistance product having a large coil cross-sectional area using a general-purpose printing screen. It is to be an issue.

  In order to solve the above-mentioned problem, the invention according to claim 1 creates a printing portion in which an electrically insulating magnetic material is printed around a conductive pattern forming a partial shape of a coil by screen printing, and the printing is performed. The laminated inductor is formed by sequentially laminating and crimping the portions, and by sequentially connecting the conductor pattern in the laminating direction to form a coil that spirals around in the laminating direction in the magnetic body. In the manufacturing method, at least two of the printed portions on which the conductive patterns having the same partial shape of the coil are printed are sequentially stacked and pressure-bonded.

  According to a second aspect of the present invention, in the first aspect of the present invention, when the two printed portions having the same partial shape of the coil are sequentially stacked and bonded together, The amount of the binder contained in the magnetic material is larger than the amount of the binder contained in the magnetic material of the other printing unit.

  Furthermore, the invention according to claim 3 is the invention according to claim 2, wherein the amount of the binder to be contained in the magnetic body of the printing part to be pressure-bonded later among the two printing parts is crimped first. The amount of the binder contained in the magnetic body of the printed part is increased.

  According to the invention described in any one of claims 1 to 3, a multilayer inductor is formed by sequentially pressing a plurality of printed portions each having an electrically insulating magnetic material printed around a conductive pattern forming a partial shape of a coil. At the time of manufacturing, at least two of the above-mentioned printing parts on which conductive patterns having the same partial shape of the coil are printed are sequentially stacked and bonded, so that the coil is compared with the case of using a normal printing screen. A multilayer inductor having a thickness dimension that is twice or more can be obtained. As a result, a low DC resistance product with a large coil cross-sectional area can be easily obtained without using a special printing screen that can form a thick-walled printing section, but using a thin-walled printing screen that has been used so far. Can be manufactured.

  In addition, according to the prototype experiment by the present inventors, when the two printed parts having the same partial shape of the coil are pressure-bonded, the binder amount of the magnetic paste in both printed parts is the same as the conventional amount. The crimping force was weak, and cracks sometimes occurred between the coils. On the other hand, in order to improve the mutual pressure-bonding property, when the binder amount of the magnetic paste in both printing parts is increased more than usual, the binder comes off badly in the firing process, and from the cavity generated in the magnetic body. There was a phenomenon of cracking.

  In general, as shown in FIG. 14, when the amount of the binder is increased, the transferability at the time of pressure bonding and the surface accuracy at the time of cutting after pressure bonding are improved, but the printability by the printing screen is deteriorated. It is known.

  Therefore, as in the invention described in claim 2, when the two printing parts having the same partial shape of the coil are pressure-bonded, the amount of the binder contained in the magnetic body of one of the printing parts is set to the other printing part. It has been found that when the amount is larger than the amount of the binder contained in the magnetic material, the desired pressure-bonding force and printability can be obtained, and cracking during firing can be prevented.

  Therefore, according to the second or third aspect of the invention, the manufacturing yield can be improved. At that time, as in the invention described in claim 3, the amount of binder contained in the magnetic body of the printed part to be pressure-bonded later is larger than the amount of binder contained in the magnetic body of the printed part that has been pressure-bonded first. By doing so, workability can also be improved, which is preferable.

It is a disassembled perspective view of the multilayer inductor manufactured by one Embodiment of this invention. FIGS. 2A and 2B show a printed portion on the upper side of the A-shaped coil in FIG. 1, where FIG. The lower side printing part of the A-shaped coil of FIG. 1 is shown, (a) is a front view, (b) is a back view. The printing part of the upper side of the B-shaped coil of FIG. 1 is shown, (a) is a front view, (b) is a back view. The printing part of the upper side of the B-shaped coil of FIG. 1 is shown, (a) is a front view, (b) is a back view. FIGS. 2A and 2B show a printed portion on the upper side of the C-shaped coil in FIG. 1, where FIG. FIGS. 2A and 2B show a printed portion on the upper side of the C-shaped coil in FIG. 1, where FIG. The printing part of the upper side of the D-shaped coil of FIG. 1 is shown, (a) is a front view, (b) is a back view. The printing part of the upper side of the D-shaped coil of FIG. 1 is shown, (a) is a front view, (b) is a back view. It is a perspective view which shows the state which crimps | bonds the printing part of FIG. 4 and the printing part of FIG. It is a graph which shows the composition of the magnetic body paste of the printing part in this embodiment. It is a perspective view which shows the coil shape of the multilayer inductor manufactured by this embodiment. It is a figure which shows the process of the manufacturing method of the multilayer inductor by general screen printing. It is a graph which shows the relationship between the amount of binders in a magnetic paste, and the change of the manufacture characteristic by this.

Hereinafter, an embodiment of a method for manufacturing a multilayer inductor according to the present invention will be described with reference to the drawings.
FIG. 1 shows a configuration of a multilayer inductor manufactured in the present embodiment. As shown in FIG. 13, this multilayer inductor forms partial shapes A, B, C, and D of a coil by screen printing. Eight layers of printed portions 1 to 8 each having a ferrite (electrically insulating magnetic material) 11 printed around the conductive patterns 10a to 10d are sequentially stacked and pressed, and each coil is cut and degreased. It is manufactured by baking later.

  And in this manufacturing method, as shown in FIG. 2 and FIG. 3, the conductive pattern 10a of the printing parts 1 and 2 is formed in the partial shape A of the same coil, and as shown in FIG. 4 and FIG. The conductive patterns 10b of the portions 3 and 4 are formed in a partial shape B of the same coil. Further, as shown in FIGS. 6 and 7, the conductive pattern 10c of the printing parts 5 and 6 is formed in a partial shape C of the same coil, and as shown in FIGS. The pattern 10d is formed in a partial shape D of the same coil.

  Here, as shown in FIG. 3B, FIG. 5B, FIG. 7B, and FIG. 9B, in the printing units 2, 4, 6, and 8, adjacent printing units having different coil shapes On the opposite surface, an insulating layer 12 is formed by printing the same electrically insulating Zn ferrite material pace as the ferrite 11 over the entire surface, and for electrically connecting adjacent conductive patterns having different coil shapes. A via hole 13 is formed.

  In order to manufacture this multilayer inductor, the printed part 1 is pressed and transferred from the surface side shown in FIG. 2 (a) onto the ferrite block 23 shown in FIG. The printed part 2 of the conductive pattern 10a having the part shape A is transferred by pressing from the surface side shown in FIG. Then, similarly, the printing units 3 to 8 are sequentially pressure-bonded onto the back surface of the printing unit 2 shown in FIG.

  At this time, the amount of binder in the paste of the ferrite 11 of the printing parts 2, 4, 6, 8 to be pressure-bonded later among the printing parts 1 to 8 formed with the partial shapes A to D of the same coil is determined first. More than the binder amount in the paste of the ferrite 11 of the printed portions 1, 3, 5, and 7 that are pressure-bonded.

  In the present embodiment, the binder amount to be contained in the ferrite 11 of the printed portions 1, 3, 5, and 7 that have been press-bonded first is set to 2 parts by weight similar to the normal paste shown in the left diagram of FIG. The amount of binder contained in the ferrite 11 of the printing parts 2, 4, 6, 8 to be pressure-bonded later was set to 10 parts by weight, which is five times as shown in the right figure of FIG.

  In this manner, after the stacking / crimping of the printing units 1 to 8 is completed in sequence, usually, a plurality of coils are formed in parallel on the same plane, so that each coil is cut and degreased. By firing after the treatment, the above-described multilayer inductor in which the coil 14 is formed in the ferrite 11 so as to be spirally wound while being superimposed in the lamination direction as shown in FIG.

  As described above, according to the method for manufacturing a multilayer inductor having the above-described configuration, the two printed portions 1 (2) on which the conductive patterns 10a to 10d having the same partial shapes A, B, C, and D of the coil 14 are printed. ) 3 (4), 5 (6), 7 (8) are laminated and pressure-bonded in sequence, so that the thickness dimension of the coil 14 is twice that of a normal laminated inductor using the same printing screen. A multilayer inductor can be obtained. As a result, a low DC resistance product with a large coil cross-sectional area can be easily obtained without using a special printing screen that can form a thick-walled printing section, but using a thin-walled printing screen that has been used so far. Can be manufactured.

  In addition, as shown in FIG. 11, two printed portions 1 (2), 3 (4), 5 () in which conductive patterns 10a to 10d having the same partial shapes A, B, C, and D of the coils are printed. 6) When the 7 (8) is pressure-bonded, the binder amount in the ferrite 11 paste of the printed portions 1, 3, 5, and 7 that has been pressure-bonded first is set to 2 parts by weight as in the case of a normal multilayer inductor. Since the binder amount in the ferrite 11 paste of the printing parts 2, 4, 6, 8 to be crimped later is set to 10 parts by weight, which is five times that of the paste, as shown in FIG. In addition, it is possible to prevent generation of cracks during firing and deterioration of surface accuracy during cutting.

  As a result, the production yield of the multilayer inductor can be improved, and in particular, the amount of the binder to be contained in the ferrite 11 of the printing units 2, 4, 6, and 8 to be crimped later is printed first. Since the amount of binder contained in the ferrite 11 of 3, 5, 7 is increased, workability at the time of pressure bonding can also be improved.

1-8 Printing part 10a-10d Conductive pattern 11 Ferrite (magnetic material)
14 Coils A to D Partial shape of coil

Claims (3)

By screen printing, a printed part in which an electrically insulating magnetic material is printed around a conductive pattern that forms a part of the coil is formed, and the printed part is sequentially stacked and pressed, and the conductive pattern is In the method of manufacturing a multilayer inductor, in which a coil that spirally circulates while being superimposed in the lamination direction in the magnetic body by sequentially connecting in the lamination direction,
A method for manufacturing a multilayer inductor, comprising: sequentially laminating and press-bonding at least two printed portions on which the conductive pattern having the same shape of the coil is printed.   When the two printing parts having the same partial shape of the coil are sequentially laminated and bonded together, the amount of the binder contained in the magnetic body of one of the printing parts is added to the magnetic body of the other printing part. The method for manufacturing a multilayer inductor according to claim 1, wherein the amount is greater than the amount of binder to be contained.   Among the two printing parts, the binder amount to be contained in the magnetic body of the printing part to be pressure-bonded later is made larger than the binder amount to be contained in the magnetic body of the printing part that has been pressure-bonded first. The method for manufacturing a multilayer inductor according to claim 2.