Low-temperature-cofired-ceramic (LTCC) tape structures including cofired ferromagnetic elements, drop-in components and multi-layer transformer

Claim 2

The structure of claim 1, characterized in that said material comprises a glass frit having a melting point of approximately 500 - 650 °C.

Claim 3

The structure (10, 36, 40, 60) of claim 1 or claim 2, characterized in that said material comprises: a ferromagnetic oxide; and a glass frit including silicon dioxide (SiO₂) and at least one material selected from the group consisting of lead oxide (PbO), bismuth oxide (Bi₂O₃); sodium oxide (Na₂O), lithium oxide (Li₂O) and potassium oxide (K₂O).

Claim 4

The structure (10, 36, 40, 60) of any of claims 1-3, characterized in that said element (18, 20; 48, 50; 82, 84) comprises a vertical interconnect (via) (54) which extends through at least one (46) of said sheets (12, 14, 16; 37; 46, 52, 58; 62-70).

Claim 5

The structure (10, 36, 40, 60) of any of claims 1-4, characterized in that said element (18, 20; 48, 50; 82, 84) is flat.

Claim 6

The structure (10, 36, 40, 60) of any of claims 1-5, characterized in that: the structure (10) further comprises an inductor (22) formed between sheets (12, 16) of said tape; and said element (18, 20) is arranged to increase the inductance of the inductor (22).

Claim 7

The structure (10, 36, 40, 60) of claim 6, characterized in that: the inductor (22) includes a flat electrical conductor (22) having a predetermined shape; and said element (18, 20; 48, 50; 82, 84) comprises a flat layer (18', 20') which is vertically aligned with said conductor (22).

Claim 8

The structure of any of claims 1-5, characterized in that: the structure (40) further comprises an electrical component (42) disposed between sheets (52; 58) of said tape; and said element (18, 20; 48, 50; 82, 84) comprises a flat layer (48, 50) which is vertically aligned with and magnetically shields said component (42).

Claim 9

A ferromagnetic material which is cofirable with and chemically non-reactive with low-temperature-cofired-ceramic (LTCC) tape, preferably for use in a structure according to any of claims 1-8, comprising: a ferromagnetic oxide; an organic vehicle; and a glass frit comprising constituents selected such that said material is sinterable using a same firing profile as and has approximately the same thermal shrinkage characteristics as said tape.

Claim 10

The material of claim 9, characterized in that the glass frit has a melting point of approximately 500 - 650 °C.

Claim 11

The material of claim 9 or 10, characterized in that the glass frit comprises silicon dioxide (SiO₂) and at least one material selected from the group consisting of lead oxide (PbO), bismuth oxide (Bi₂O₃), sodium oxide (Na₂O), lithium oxide (Li₂O) and potassium oxide (K₂O).

Claim 12

The material of any of claims 9-11, further characterized by a solvent in a proportion selected such that said material is in fluid form and has a predetermined viscosity.

Claim 13

The material of any of claims 9-11, characterized in that said vehicle is selected such that said material is in solid form and has a predetermined flexibility.

Claim 14

The material of claim 13, characterized in that said material is formed as a tape sheet.

Claim 15

The material of any of claims 3-14, characterized in that the ferromagnetic oxide comprises nickel-zinc ferrite (NiZnFe₃O₄).

Claim 16

The material of any of claims 3-14, characterized in that the ferromagnetic oxide is selected from the group consisting of spinels, garnets and magnetoplumbites.

Claim 18

The method of claim 17, characterized in that step (b) comprises the substeps of: (e) providing said material as a fluid; and (f) applying said material to said surface of the first sheet (12, 14, 16; 37; 46, 52, 58; 62-70) in a predetermined pattern to form said element (18, 20; 48, 50; 82, 84).

Claim 19

The method of claim 17, characterized in that step (b) comprises the substeps of: (e) providing said material as a flexible tape; (f) cutting said tape to a predetermined shape to form said element (18, 20; 48, 50; 82, 84); and (g) placing said element (18, 20; 48, 50; 82, 84) on said surface of the first sheet (12, 14, 16; 37; 46, 52, 58; 62-70).

Claim 21

A cofired ceramic tape circuit structure (100, 130, 170, 250), comprising: a plurality of sandwiched sheets (100-110; 134-140; 172-176; 252-260) of low-temperature-cofired-ceramic (LTCC) tape having a cavity (112; 132; 178; 252a-260a) formed in at least one of said sheets (100-110; 134-140; 172-176; 252-260); and an electromagnetic component (114; 142; 180; 300) disposed in said cavity (112; 132; 178; 252a-260a) formed of a material which is cofirable with said tape.

Claim 22

The structure of claim 21, characterized in that said cavity (178; 252a-260a) extends through all of said sheets (172-176; 252-260).

Claim 23

The structure of claim 21, characterized in that said cavity (112, 132) extends from a surface of the structure (100, 130) through at least one (104-108; 134-138) but not all of said sheets (100-110; 134-140; 172-176; 252-260).

Claim 24

The structure of claim 21, characterized in that said cavity (112) extends through at least one (104-108) internal sheet but not the external sheets (102, 110) of the structure (100).

Claim 25

The structure of claim 21, characterized in that the structure (250) further comprises an electrical inductor (254b,c,d; 256b,c,d; 258b,c,d) which is formed on one of said sheets (254, 256, 258) and at least partially surrounds the cavity (254a, 256a, 258a); and said component (300) comprises a ferromagnetic material and constitutes a core of said inductor (254b,c,d; 256b,c,d; 258b,c,d).

Claim 27

The method of claim 26, further characterized by the step, performed prior to step (c), of: (e) prefiring said component (114; 142; 180, 300).

Claim 28

A cofired ceramic tape transformer structure (250), comprising: a plurality of sandwiched sheets (252-260) of low-temperature-cofired-ceramic (LTCC) tape; a primary coil, including: a plurality of vertically aligned, arcuate primary electrical conductors (254b,d; 256b,d; 258b,d) formed on surfaces of the sheets (254, 256, 258); and a plurality of primary vertical interconnects (vias) (264-280) which extend through said sheets (254, 256, 258) and interconnect ends of said primary conductors (254b,d; 256b,d; 258b,d) on adjacent sheets respectively to form a continuous electrical path through said primary conductors (254b,d; 256b,d; 258b,d); and a secondary coil, including: a plurality of vertically aligned, arcuate secondary electrical conductors (254c, 256c, 258c) formed on surfaces of the sheets (254, 256, 258); and a plurality of secondary vertical interconnects (vias) (286-292) which extend through said sheets (254, 256, 258) and interconnect ends of said second secondary conductors (254c, 256c, 258c) on adjacent sheets (254, 256, 258) respectively to form a continuous electrical path through said secondary conductors (254c, 256c, 258c).

Claim 29

The transformer structure of claim 28, characterized in that: said primary conductors (254b,d; 256b,d; 258b,d) comprise two radially spaced arcuate first and second conductor sections (254b, 256b, 258b; 254d, 256d, 258d); and said primary vias (264-280) interconnect said first and second conductor sections (254b, 256b, 258b; 254d, 256d, 258d) to form said continuous electrical path as including a first electrical path section through said first conductor sections (254b-258b) and a second electrical path section through said second conductor sections (254d-258d).

Claim 30

The transformer structure of claim 28, characterized in that: said secondary conductors (254c, 256c, 258c) comprise two radially spaced arcuate first and second conductor sections; and said secondary vias (286-292) interconnect said first and second conductor sections to form said continuous electrical path as including a first electrical path section through said first conductor sections and a second electrical path section through said second conductor sections.