MICROMINIATURE MONOLITHIC FERROCERAMIC TRANSFORMER

• US 3,833,872 A
• Filed: 06/13/1972
• Issued: 09/03/1974
• Est. Priority Date: 06/13/1972
• Status: Expired due to Term

• Current Assignee: Ira R. Marcus, William L. Muckelroy
• Original Assignee: Ira R. Marcus, William L. Muckelroy
• Inventors: Marcus, Ira R., Muckelroy, William L.
• Primary Examiner(s): Kozma, Thomas J.
• Application Number:
  US05/262,406
• Time in Patent Office: 812 Days
• Field of Search: 336/83,180,200,183,232,221 340/174CC,174JA
• US Class Current: 336/83
• CPC Class Codes: H01F 2027/2809 on stacked layers
• CPC Class Codes: H01F 27/255 made from particles H01F27/26 takes precedence
• CPC Class Codes: H01F 41/02 for manufacturing cores, coils, or magnets H01F41/14 takes precedence; for dynamo-electric machines H02K15/00
• CPC Class Codes: H01F 41/0246 Manufacturing of magnetic circuits by moulding or by pressing powder magnetic cores made by moulding or by pressing powder H01F27/255; soft magnetic particles H01F1/20, H01F1/36
• CPC Class Codes: H01F 41/046 structurally combined with ferromagnetic material

Abstract

A monolithic microminiature transformer element comprising at least two separate contiguous windings of conductive metal film, each having an interconnecting magnetically permeable core of refractory material, immersed in a rectangular block of stratified refractory material. The element is a contiguous mass of ceramic material, especially alumina, primary and secondary transformer windings formed by printing or photoetching loops on a rectangular piece of ceramic sheet. A method for making this transformer element wherein paths of conductive material are deposited onto thin unsintered magnetically permeable ceramic sheet with holes for interconnection therein to form windings of said transformer and wherein said holes are aligned and said sheets are laminated such that upon sintering said metal forms a contiguous conductive path and provides a primary or secondary winding for said transformer, and wherein said path is immersed in a contiguous block of ceramic.

Claims

1. A microminiature transformer comprising:

a. a monolithic block comprised of a plurality of appositioned strata thermally fused together, each stratum comprised of sintered refractory ceramic dielectric material;

b. an electrically-insulated magnetically-permeable powder dispersed in said strata;

c. individual conductive metal primary spirals deposited on some of the surfaces of said strata, said primary spirals on each said stratum being coaxially located and enclosed by said block;

d. individual conductive metal secondary spirals deposited on some of the surfaces of said strata, said secondary spirals on each said stratum being coaxially located and enclosed by said block;

e. a first hole in each said stratum for housing a means for interconnecting each primary spiral;

f. a second hole in each said stratum for housing a means for interconnecting each secondary spiral;

g. said means for interconnecting each primary spiral comprising a metal film deposited on the inside cylindrical wall of each of said first hole;

h. said means for interconnecting each secondary spiral comprising a metal film deposited on the inside cylindrical wall of each of said second hole.

2. The microminiature monolithic transformer element of claim 1 wherein said primary spirals comprise a primary transformer winding and wherein said secondary spirals comprise a secondary transformer winding and wherein said dispersed powder provides a magnetically permeable flux link for said windings.

3. The microminiature transformer of claim 2 further comprising at least four deposited metal bonding pads, two of which are located on one face at said block, two more of which are located on the opposite face of said block, whereby one parallel and coaxial pair of said bonding pads form the terminations of the primary winding and another parallel and coaxial pair of said bonding pads form the terminations of the secondary winding.

4. The microminiature transformer of claim 3 wherein said powder is selected from the group consisting of 2-81 permalloy and carbonyl iron.

5. The microminiature transformer of claim 4 wherein said primary and said secondary spirals are coaxially oriented.

6. The microminiature transformer of claim 4 wherein said primary spirals are coaxially arranged about a first axis and wherein said secondary spirals are coaxially arranged about a second axis, said second axis being located a distance away from said first axis greater than the sum of the combined maximum radii of said primary and said secondary spirals.

7. The microminiature transformer of claim 5 wherein said strata are of equal thickness.

8. The microminiature transformer of claim 5 wherein said metal spirals, said metal film, and said metal bonding pads are thermally matched to said strata.

9. The microminiature transformer of claim 6 wherein said strata are of equal thickness.

10. The microminiature transformer of claim 6 wherein said metal spirals, said metal film, and said metal bonding pads are thermally matched to said strata.

11. The microminiature transformer of claim 1 further comprising melted glass frit dispersed in said conductive metal spirals and said metal film, whereby said frit provides a ceramic-to-metal bond.