Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F17/00—Fixed inductances of the signal type 
  • H01F17/0006—Printed inductances
  • H01F17/0013—Printed inductances with stacked layers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F27/00—Details of transformers or inductances, in general

Definitions

• the present invention relates to a multilayer inductor having a structure in which a coil is embedded in a magnetic material. More specifically, the inner portion of the coil is entirely a magnetic material, and an electrically insulating nonmagnetic material is provided outside the coil.
• the present invention relates to a multilayer inductor having a structure in which two or more such nonmagnetic layers are symmetrically positioned in the stacking direction with respect to the center of the stack. This multilayer inductor is particularly useful for inductors for DC-DC converters that require high noise.
• Transformers and choke coils used in power circuits such as DC—DC converters were generally configured with the coil wired to the magnetic core.
• power circuit components have become smaller.
• multilayer chip components have been developed and put to practical use.
• a multilayer inductor an electrically insulating magnetic layer and a conductor pattern are alternately stacked and the conductor patterns are sequentially connected, so that a coil that wraps around in a spiral shape while being superimposed in the stacking direction in the magnetic body.
• both ends of the coil are drawn to the outer surface of the laminated chip via lead conductors and connected to electrode terminals. That is, the coil is embedded in a chip-type magnetic body.
• the magnetic layer and the conductor pattern are formed and stacked using, for example, a screen printing technique.
• Such a multilayer inductor is characterized in that the required inductance can be obtained with a relatively small number of magnetic leaks because the coil is surrounded by a magnetic material. Is suitable.
• the AC resistance increases at low DC bias (thus, the loss due to standby current is large), and even with a small coil current (excitation current), the magnetic saturation of the magnetic material is reduced. There is a problem that a sudden inductance drop occurs due to the sum (that is, the DC superimposition characteristic is bad).
• the present applicant replaces a part of the entire magnetic layer with a non-magnetic layer, thereby interposing a magnetic gap in the multilayer inductor, thereby increasing the magnetic saturation level, thereby improving the transformer and choke.
• a multilayer inductor that can obtain a sufficient rated current as a coil. See JP 2005-45108 A.
• the problem to be solved by the present invention is to obtain a high inductance, to exhibit excellent DC superposition characteristics, and to suppress AC resistance at the time of low DC bias.
• a multilayer inductor has an electrical insulating magnetic layer and a conductor pattern that are alternately stacked, and the conductor patterns are sequentially connected to each other, thereby spiraling in a magnetic material while being superimposed in the stacking direction.
• a coil formed so as to circulate, an electrode terminal provided on the outer surface of the multilayer chip, and a lead conductor for connecting both ends of the coil to the electrode terminal on the outer surface of the multilayer chip,
• Two or more electrically insulating nonmagnetic layers are arranged symmetrically in the stacking direction with respect to the center of the stacked body over the entire outside of the coil except for the inside.
• the electrically insulating nonmagnetic layer extends, for example, between the conductor pattern layer forming a part of the coil and the conductor pattern layer overlapping the gap in the stacking direction and outside the coil. However, it may be provided in place of the magnetic layer so as to surround the conductor pattern forming a part of the coil in the same plane as the conductor pattern.
• FIG. 1 is an explanatory diagram showing an example of a multilayer inductor according to the present invention.
• FIG. 2 is a longitudinal sectional view showing another embodiment of the present invention.
• FIG. 3 is a graph showing a difference in DC superposition characteristics between the product of the present invention and a comparative example.
• a decrease in inductance due to an increase in DC superimposed current is caused by increasing the magnetic flux generated from the coil due to the increase in DC current and saturating the magnetic material.
• it is effective to reduce the cross-sectional area through which the magnetic flux passes.
• a decrease in cross-sectional area through which magnetic flux passes results in a decrease in inductance.
• the non-magnetic material that is, the force that disposes the non-magnetic material instead of the magnetic layer, minimizes the decrease in inductance and extends the DC superposition characteristics. Shape is important.
• an electrically insulating nonmagnetic layer extends over the entire outer surface except for the inner portion of the coil, and two or more such nonmagnetic layers are formed relative to the center of the multilayer body. It is configured so that it is positioned symmetrically in the stacking direction. Specifically, a force is provided to spread between the layers of conductive patterns that overlap with each other at an interval in the vertical direction and connected to the outside of the coil, or on the same plane as the conductive pattern so as to surround the conductive pattern. Provided in place of the magnetic layer.
• FIG. 1 is an explanatory view showing an embodiment of the multilayer inductor according to the present invention.
• A shows the appearance
• B shows the top surface of the conductor pattern
• C shows the longitudinal section
• D shows the structure of the nonmagnetic layer.
• This multilayer inductor 10 is a chip component for surface mounting that has a substantially rectangular parallelepiped shape. Almost all of the coil is embedded in a material made of a magnetic material, and both ends of the coil are at both ends of the chip. It is structured to be connected to the electrode terminal 12 that is formed in (A in Fig. 1).
• the internal coil structure is formed by printing a substantially annular (or semi-annular) conductive pattern 20 and an electrically insulating magnetic layer 22 by screen printing or the like and alternately laminating them.
• the conductor pattern 20 is connected in a magnetic body by the magnetic layer 22 so as to circulate spirally while being superimposed in the stacking direction to form a coil.
• the conductor pattern is wound in a rectangular shape while being bent at a right angle. Both ends of the coil are respectively drawn out to opposite end faces of the outer surface of the multilayer chip via lead conductors 24 and connected to electrode terminals.
• an electrically insulating nonmagnetic layer 26 is provided in place of the magnetic layer, and two such nonmagnetic layers 26 are symmetrical in the stacking direction with respect to the center of the stack. It is located and is characterized by this point.
• a nonmagnetic layer 26 is provided between the first layer and the second layer, and between the third layer and the fourth layer from the bottom.
• the inside of the coil must be magnetic (see D in Fig. 1).
• the nonmagnetic layer 26 has a rectangular frame shape and the inside thereof is a rectangular magnetic layer 28.
• the boundary between the nonmagnetic material and the magnetic material is made slightly smaller than the inner contour line of the conductor pattern 20 to prevent a short circuit from occurring due to the inflow of the conductor paste. It is preferable that the size is such that it can be mounted on 26.
• the multilayer inductor having the structure of the present invention can satisfy the specifications normally required with a relatively small number of coils in applications such as a DC-DC converter.
• the optimum position for inserting the non-magnetic layer is appropriately determined according to the coil shape, the number of coils, and the like.
• FIG. 2A Another embodiment of the multilayer inductor according to the present invention is shown in FIG. In FIG. 2A, an electrically insulating nonmagnetic layer 32 is provided in place of the magnetic layer on the same plane as the conductor pattern 30 so as to surround the conductor pattern 30 forming a part of the coil, and In this structure, two nonmagnetic layers 32 are symmetrically arranged in the stacking direction with respect to the center of the stack.
• the other part is composed of an electrically insulating magnetic layer 34.
• Each of these layers is formed by a screen printing method or the like.
• This embodiment is also an example of the same number of coils as in the above embodiment, and the non-magnetic layer is provided at the position of the second and third conductor patterns in the lower force.
• FIG. 2B is a modified example of the multilayer inductor shown in FIG. 2A, in which the thickness of the nonmagnetic layer is changed. It is preferable to widen (thicken) the gap between the conductor patterns 30 that are in a relationship of being overlapped with each other at an interval in order to avoid a short circuit. On the other hand, if the thickness of the nonmagnetic layer 32 is controlled and reduced, the inductance can be increased. Therefore, in FIG. 2B, the thickness of the nonmagnetic layer 32 is controlled to be thin so as to obtain a high inductance.
• the other part is composed of an electrically insulating magnetic layer 34. Each of these layers is formed by a screen printing method or the like. This embodiment is also an example of several coils, and the lower force is also provided with a nonmagnetic layer at the positions of the second and third layer conductor patterns.
• FIG. 1 An example of the measurement result is shown in FIG.
• the DC superposition characteristics of three types of multilayer inductors with the same dimensions and the same force (a) to (c) were measured.
• the product of the present invention of (a) has the same structure as the multilayer inductor shown in FIG. 1, and although the two nonmagnetic layers are interposed, the inside of the coil is all magnetic.
• (b) and (c) are comparative examples, both of which have a structure in which a nonmagnetic layer is interposed over the entire horizontal cross section of the chip as described in JP-A-2005-45108. There is also a nonmagnetic layer inside the coil!
• Comparative Example 1 of (b) two nonmagnetic layers are provided on the top and bottom, and in Comparative Example 2 of (c), one nonmagnetic layer is provided in the center.
• the hatched portion represents the conductor pattern (coil)
• the dotted portion represents the nonmagnetic layer
• the other portions represent the magnetic layer.
• the inside of the coil is made of a magnetic material so that the magnetic flux can easily pass, and the outside is configured so as to control the passage of the magnetic flux by arranging a nonmagnetic layer in part.
• the DC superposition characteristics can be improved.
• the number of coils can be appropriately increased or decreased according to the required specifications. However, if the number of coils is excessively large, the number of manufacturing steps is increased and the cost is increased. Therefore, the number of coils is preferably set to the minimum necessary.
• the multilayer inductor according to the present invention two or more layers in which the inside of the coil is a magnetic body and the outside is a non-magnetic body are inserted symmetrically in the stacking direction with respect to the center of the stack! With this configuration, excellent direct current superimposition characteristics are exhibited while exhibiting high inductance, and the AC resistance during low DC bias can be kept low. This makes it possible to obtain multilayer inductors that are particularly useful for power circuits and power circuits such as DC-DC converters.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Coils Or Transformers For Communication (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=37396544

Family Applications (1)

Country Status (3)

Families Citing this family (16)

Citations (6)

Family Cites Families (2)

• 2005
  • 2005-05-10 JP JP2005136911A patent/JP4873522B2/ja active Active
• 2006
  • 2006-05-09 KR KR1020077018625A patent/KR101285646B1/ko active IP Right Grant
  • 2006-05-09 WO PCT/JP2006/309306 patent/WO2006121036A1/ja active Application Filing

Patent Citations (6)

Also Published As

Similar Documents

Legal Events