EP0530125A2 - Chip-Transformator und Herstellungsverfahren eines Chip-Transformators - Google Patents

Chip-Transformator und Herstellungsverfahren eines Chip-Transformators Download PDF

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Publication number
EP0530125A2
EP0530125A2 EP92610058A EP92610058A EP0530125A2 EP 0530125 A2 EP0530125 A2 EP 0530125A2 EP 92610058 A EP92610058 A EP 92610058A EP 92610058 A EP92610058 A EP 92610058A EP 0530125 A2 EP0530125 A2 EP 0530125A2
Authority
EP
European Patent Office
Prior art keywords
ferrite
conductor path
sheets
chip transformer
path segments
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP92610058A
Other languages
English (en)
French (fr)
Other versions
EP0530125A3 (en
Inventor
Jens Peter Holm
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
FERROPERM COMPONENTS APS
Original Assignee
FERROPERM COMPONENTS APS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by FERROPERM COMPONENTS APS filed Critical FERROPERM COMPONENTS APS
Publication of EP0530125A2 publication Critical patent/EP0530125A2/de
Publication of EP0530125A3 publication Critical patent/EP0530125A3/en
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/14—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for applying magnetic films to substrates
    • H01F41/16—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for applying magnetic films to substrates the magnetic material being applied in the form of particles, e.g. by serigraphy, to form thick magnetic films or precursors therefor
    • 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

Definitions

  • the invention relates to a chip transformer comprising a substrate carrying a plurality of ferrite sheets, at least some of the ferrite sheets being provided with one or several conductor path segments, where the conductor path segment(s) on each ferrite sheet is/are optionally connected to one or more conductor path segments on one or more of the other ferrite sheets to form a primary winding and a secondary winding isolated from said primary winding.
  • Small transformers are typically used as antennae transformers for impedance matching so as to remove spurious signals after a mixing element, to impedance transformation, or as directional couplers.
  • these transformers were wound on a core of ferrite.
  • Such transformers are relatively expensive.
  • they are not particularly suited for surface mounting and can only be used at frequencies below 500 MHz. Attempts have been made at solving this problem by forming the transformer as a transmission line transformer with the unfortunate result, however, that problems arise in maintaining a correct characteristic impedance. Accordingly, a succeeding manual trimming is necessary.
  • US-PS No. 4,803,453 discloses a laminated transformer comprising a plurality of ferrite sheets having surfaces on which conductor patterns are formed so as to provide the primary and the secondary winding, respectively. However, a predetermined distance must exist between the individual windings and between the primary and the secondary windings.
  • the object of the present invention is to provide a chip transformer allowing a reduction of the distance between the individual windings and between the primary and the secondary winding.
  • the chip transformer according to the present invention is characterised by the ferrite material being composed as follows Li 0,5(1+t-z-c) Zn z , Mn m , Ti t , Co c , Fe (1-0,2z-0,6t-0,4m-0,2- ⁇ ) where 0 ⁇ t ⁇ 0,2; 0,2 ⁇ z ⁇ 0,5; 0,2 ⁇ m ⁇ 0,4; 0,02 ⁇ c ⁇ 0,05; and ⁇ is of the magnitude 0,06, Bi2O3 also being added.
  • This material has a relatively high resistivity and as the losses involved are lower than the ones involved in connection with conventional transformers, it is possible to arrange the windings closer to one another, and a higher coupling factor is rendered possible due to the close arrangement of the windings. Furthermore the capacity is reduced between the primary and the secondary winding.
  • the substrate may be a ferrite sheet.
  • the invention relates furthermore to a method of producing a chip transformer by way of tape-casting or thick-film technology, and whereby a plurality of ferrite sheets is applied to a substrate, at least some of the sheets being provided with one or several conductor path segments, where the conductor path segment(s) on each ferrite sheet is/are optionally connected to one or more conductor path segments on one or more of the other ferrite sheets to form a primary winding and a secondary winding isolated from said primary winding.
  • the method according to the invention is characterised by the ferrite material used being composed as follows Li 0,5(1+t-z-c) Zn z , Mn m , Ti t , Co c , Fe (1-0,2z-0,6t-0,4m-0,2c- ⁇ ) where 0 ⁇ t ⁇ 0,2; 0,2 ⁇ z ⁇ 0,5; 0,2 ⁇ m ⁇ 0,4; 0,02 ⁇ c ⁇ 0,05; and ⁇ is of the magnitude 0,06, Bi2O3 also being added to achieve a sufficiently high resistivity.
  • the resulting method is particularly suited for the production of a chip transformer.
  • the chip transformer shown in Figure 1 comprises a base in form of a substrate, on which a plurality of ferrite sheets are arranged.
  • the embodiment of Figure 1 includes a total of eight ferrite sheets 1 to 8.
  • the base can optionally be omitted provided the ferrite sheets are sufficiently rigid.
  • conductor path segments are applied to the ferrite sheets 1, 2, 6, 7, and 8 to form portions of the primary winding, electric connections being provided between the conductor path segments to form the entire primary winding.
  • the secondary winding can be provided in a similar manner.
  • the electric connections between the sheets can for instance be provided by through holes in the ferrite sheets.
  • the conductor path segments are preferably made of Ag or Ag/Pd.
  • the ferrite material is of the following composition Li 0,5(1+t-z-c) Zn z , Mn m , Ti t , Co c , Fe (1-0,2z-0,6t-0,4m-0,2c- ⁇ ) where 0 ⁇ t ⁇ 0,2; 0,2 ⁇ z ⁇ 0,5; 0,2 ⁇ m ⁇ 0,4; 0,02 ⁇ c ⁇ 0,05; and ⁇ is of the magnitude 0,06.
  • a ferrite material is obtained which is so dense that a migration of the metals of the conductor path segments is avoided.
  • the ferrite material Prior to application of the individual ferrite sheet, the ferrite material is mixed with a polymer binder, such as polyvinyl butyral. The mixture is tape-cast to a thickness of 20 to 200 ⁇ m. Holes are punched in the individual ferrite sheet where an electric connection is to be provided between the sheets, such as at 2 a , 6 a , and 8 a in Figure 1. The holes are typically of a diameter of about 0.25 mm.
  • Conductor material such as Ag or Ag/Pd
  • the desired conductor path segments are applied for instance by way of silk printing followed by a stacking of the ferrite sheets. After the stacking, the sheets are pressed together while subjected to pressure and heat.
  • the total thickness of the ferrite sheets between the primary and the secondary windings and the mutual orientation of the ferrite sheets determine the mutual induction between the primary and the secondary windings and the characteristic impedance.
  • the secondary winding is provided on sheet No. 4 and is formed by a loop corresponding to 3/4 of a winding with the result that the secondary winding presents an inductance of approximately 56 nH.
  • the primary winding is formed by 21 ⁇ 2 winding and presents an inductance of about 0.5 to 1 ⁇ H.
  • the primary winding can comprise more or less windings.
  • the primary winding is composed of twenty windings, it presents an inductance of about 10 ⁇ H.
  • Figure 2 illustrates the final chip transformer comprising the stacked sheets of ferrite.
  • the dimensions of the chip transformer are for instance 3.2 x 2.5 mm. It appears that the outer terminals 11, 12 of the primary winding are placed at the ends, whereas the outer terminals 13, 14 of the secondary winding are placed at the sides. These outer terminals 11, 12, 13, 14 are applied by way of conventional chip termination technique, and the termination material is for instance palladium silver.
  • the conductor paths are made of Ag, Ag/Pd or other precious metals.
  • a particular advantage of the ferrite material used is that the sintering temperature is so low that it is possible to use conductor paths of Ag or Ag/Pd.
  • the conductor paths are typically of a width of a few hundred ⁇ m.
  • the isolation resistance between the primary and the secondary winding is typically more than 1000 M ⁇ , which is sufficient for most fields of application.
  • the capacity between the primary and the secondary winding is typically 0.1 to 10 pF.
  • the coupling factor between the windings is 0.7 to 1.0.
  • the transformer is able to stand at least 200 V DC.
  • the chip transformer is suited for surface mounting and can for instance be used in connection with telecommunication equipment, such as antenna transformers for impedance matching or as directionnal couplers in an antenna distribution system.
  • the chip transformer is furthermore suited for mass production as no succeeding manual trimming is necessary.
  • Each ferrite sheet is preferably manufactured by way of tape-casting, where the ferrite material is pressed by way of pressure and heat whereafter the binding agent is burnt and the material is sintered. Thick-film technology can, however, also be used.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Coils Or Transformers For Communication (AREA)
  • Soft Magnetic Materials (AREA)
EP19920610058 1991-08-23 1992-08-21 A chip transformer and a method of producing a chip transformer Withdrawn EP0530125A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DK150291A DK150291A (da) 1991-08-23 1991-08-23 Chiptransformer og fremgangsmaade til fremstilling af samme
DK1502/91 1991-08-23

Publications (2)

Publication Number Publication Date
EP0530125A2 true EP0530125A2 (de) 1993-03-03
EP0530125A3 EP0530125A3 (en) 1993-05-19

Family

ID=8105503

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19920610058 Withdrawn EP0530125A3 (en) 1991-08-23 1992-08-21 A chip transformer and a method of producing a chip transformer

Country Status (2)

Country Link
EP (1) EP0530125A3 (de)
DK (1) DK150291A (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0632472A1 (de) * 1993-06-01 1995-01-04 Eaton Corporation Stromwandler mit einem laminierten Ringkern und mit einem Leiterrahmen
EP0877396A1 (de) * 1997-05-09 1998-11-11 International Business Machines Corporation Metall/Ferrit laminierte Magnet
DE19811083C1 (de) * 1998-03-13 1999-09-30 Siemens Matsushita Components Induktives Bauelement und Verfahren zur Herstellung
WO2000060619A1 (en) * 1999-04-01 2000-10-12 Midcom, Inc. Multi-layer transformer apparatus and method
EP1290703A1 (de) * 1998-07-06 2003-03-12 Midcom, Inc. Mehrschichtiger transformator mit elektrischer verbindung in einem magnetkern
US6653776B1 (en) 2000-06-28 2003-11-25 International Business Machines Corporation Discrete magnets in dielectric forming metal/ceramic laminate and process thereof

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54101810A (en) * 1978-01-28 1979-08-10 Tohoku Metal Ind Ltd Magnetic material having square hysterisis loop
FR2604287A1 (fr) * 1986-09-22 1988-03-25 Murata Manufacturing Co Transformateur feuillete

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54101810A (en) * 1978-01-28 1979-08-10 Tohoku Metal Ind Ltd Magnetic material having square hysterisis loop
FR2604287A1 (fr) * 1986-09-22 1988-03-25 Murata Manufacturing Co Transformateur feuillete

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Week 7938, Derwent Publications Ltd., London, GB; AN 79-68880 & JP-A-54 101 810 (TOHM) 10 August 1979 *
IEEE TRANSACTIONS ON COMPONENTS,HYBRIDS,AND MANUFACTURING TECHNOLOGY vol. 8, no. 1, March 1985, NEW YORK US pages 221 - 227 C.K.MAITI ET AL *
NEW ELECTRONICS.INCORPORATING ELECTRONICS TODAY vol. 23, no. 7, July 1990, LONDON GB pages 45 - 46 A.MACLEOD *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0632472A1 (de) * 1993-06-01 1995-01-04 Eaton Corporation Stromwandler mit einem laminierten Ringkern und mit einem Leiterrahmen
EP0877396A1 (de) * 1997-05-09 1998-11-11 International Business Machines Corporation Metall/Ferrit laminierte Magnet
DE19811083C1 (de) * 1998-03-13 1999-09-30 Siemens Matsushita Components Induktives Bauelement und Verfahren zur Herstellung
EP1290703A1 (de) * 1998-07-06 2003-03-12 Midcom, Inc. Mehrschichtiger transformator mit elektrischer verbindung in einem magnetkern
EP1290703A4 (de) * 1998-07-06 2009-06-17 Nascentechnology Inc Mehrschichtiger transformator mit elektrischer verbindung in einem magnetkern
WO2000060619A1 (en) * 1999-04-01 2000-10-12 Midcom, Inc. Multi-layer transformer apparatus and method
US6198374B1 (en) 1999-04-01 2001-03-06 Midcom, Inc. Multi-layer transformer apparatus and method
US6653776B1 (en) 2000-06-28 2003-11-25 International Business Machines Corporation Discrete magnets in dielectric forming metal/ceramic laminate and process thereof
US6974358B2 (en) 2000-06-28 2005-12-13 International Business Machines Corporation Discrete magnets in dielectric forming metal/ceramic laminate and process thereof

Also Published As

Publication number Publication date
EP0530125A3 (en) 1993-05-19
DK150291D0 (da) 1991-08-23
DK150291A (da) 1993-02-24

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