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

• US 5,312,674 A
• Filed: 07/31/1992
• Issued: 05/17/1994
• Est. Priority Date: 07/31/1992
• Status: Expired due to Term

• Current Assignee: OL Security LLC (Intellectual Ventures LLC)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Gonzalez, Carlos H., Lusher, David M., Haertling, Carol, Shapiro, Andrew A., Goodman, Charles A., Pond, Ramona G., Washburn, Robert D., McClanahan, Robert F.
• Primary Examiner(s): Ryan, Patrick J.
• Assistant Examiner(s): LAM, CATHY FONG FONG
• Application Number:
  US07/923,409
• Time in Patent Office: 655 Days
• Field of Search: 501/17, 501/32, 252/62, 428/209, 428/210
• US Class Current: 428/210
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/32188 the layer connector connecting to a bonding area protruding from the surface of the item
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48472 the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 23/055 the leads having a passage through the base H01L23/057 takes precedence
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 25/165 Containers
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01012 Magnesium [Mg]
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01025 Manganese [Mn]
• CPC Class Codes: H01L 2924/01039 Yttrium [Y]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/15153 : the die mounting substrate comprising a recess for hosting the device
• CPC Class Codes: H01L 2924/1517 : Multilayer substrate
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/30107 : Inductance
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding
• CPC Class Codes: H05K 1/0306 : Inorganic insulating substrates, e.g. ceramic, glass
• CPC Class Codes: H05K 1/092 : Dispersed materials, e.g. conductive pastes or inks
• CPC Class Codes: H05K 1/165 : incorporating printed inductors
• CPC Class Codes: H05K 2201/086 : for inductive purposes, e.g. printed inductor with ferrite core
• CPC Class Codes: H05K 3/4611 : by laminating two or more circuit boards H05K3/4652 takes precedence
• CPC Class Codes: H05K 3/4629 : laminating inorganic sheets comprising printed circuits, e.g. green ceramic sheets
• CPC Class Codes: H05K 3/4688 : Composite multilayer circuits, i.e. comprising insulating layers having different properties having a special base or central core H05K3/4602
• CPC Class Codes: Y10T 428/24917 : including metal layer
• CPC Class Codes: Y10T 428/24926 : including ceramic, glass, porcelain or quartz layer

Abstract

A ferromagnetic material (18,20) in ink or tape form is sinterable using a same firing profile as and has approximately the same thermal shrinkage characteristics as low-temperature-cofired-ceramic (LTCC) tape, and is chemically non-reactive therewith. The ferromagnetic material (18,20) is applied to the surfaces of LTCC tape sheets (12,14,16) to form desired elements such as cores for inductors (22) and transformers and magnetic shields. Ferromagnetic vertical interconnects (vias) (54) can be formed by punching holes (56) through tape sheets (46) and filling them with ferromagnetic ink. The tape sheets (12,14,16) and ferromagnetic elements (18,20) are laminated together and cofired to form an integral structure (10). Ferromagnetic and non-magnetic components (114) can be fabricated separately and inserted into cavities (104a, 106a,108a) in tape sheets (104,106,108) prior to cofiring. A multi-layer transformer (250) includes primary (254b, 256b,258b,254d,256d,258d) and secondary (254c,256c,258c) coils, each being formed of vertically aligned, arcuate conductors which are printed on separate tape sheets (254,256,258) and vertically interconnected at their ends to form continuous electrical paths therethrough.

Claims

1. A cofired ceramic tape circuit structure, comprising;

a plurality of sandwiched sheets of low-temperature-cofired-ceramic (LTCC) tape; and

a ferromagnetic element sandwiched between sheets of said tape, said element being formed of a material which is substantially chemically non-reactive with, is sinterable using a same firing profile as and has approximately the same thermal shrinkage characteristics as said tape,

wherein said the ferromagnetic material comprises a ferromagnetic oxide, a glass powder (or frit) and an organic binder.

2. A structure as in claim 1, in which said material comprises a glass frit having a melting point of approximately 500-650°

C.

3. A structure as in claim 1, in which said material comprises;

a ferromagnetic oxide powder; and

a glass frit including silicon dioxide (SiO₂) and at least one material selected from the group consisting of lead oxide (PbO), bismuth oxide (Bi₂ O₃), sodium oxide (Na₂ O), lithium oxide (Li₂ O), and potassium oxide (K₂ O).

4. A structure as in claim 1, in which said element comprises a vertical interconnect (via) which extends through at least one of said sheets.

5. A structure as in claim 1, in which said element is flat.

6. A structure as in claim 1, in which:

the structure further comprises an inductor formed between sheets of said tape; and

said element is arranged to increase the inductance of the inductor.

7. A structure as in claim 6, in which:

the inductor includes a flat electrical conductor having a predetermined shape; and

said element comprises a flat layer which is vertically aligned with said conductor.

8. A structure as in claim 1, in which:

the structure further comprises an electrical component disposed between sheets of said tape; and

said element comprises a flat layer which is vertically aligned with and magnetically shields said component.

9. A ferromagnetic material which is cofirable with and chemically non-reactive with low-temperature-cofired-ceramic (LTCC) tape, 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.

10. A material as in claim 9, in which the glass frit has a melting point of approximately 500-650°

C.

11. A material as in claim 10, in which the glass frit comprises silicon dioxide (SiO₂) and at least one material selected from the group consisting of lead oxide (PbO), bismuth oxide (Bi₂ O₃), sodium oxide (Na₂ O) lithium oxide (Li₂ O) and potassium oxide (K₂ O).

12. A material as in claim 9, further comprising a solvent in a proportion selected such that said material is in fluid form and has a ink viscosity.

13. A material as in claim 9, in which said vehicle is selected such that said material is in solid form and has tape flexibility.

14. A material as in claim 13, in which said material is formed as a tape sheet.

15. A material as in claim 9, in which the ferromagnetic oxide comprises nickel-zinc ferrite (NiZnFe₃ O₄).

16. A material as in claim 9, in which the ferromagnetic oxide is selected from the group consisting of spinels, including magnetoplumbites and garnets.