Microwave/millimeter wave circuit structure with discrete flip-chip mounted elements

• US 5,757,074 A
• Filed: 07/29/1996
• Issued: 05/26/1998
• Est. Priority Date: 07/07/1995
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Larson, Lawrence E., Macdonald, Perry A., Matloubian, Mehran, Rensch, David B.
• Primary Examiner(s): Thomas, Tom
• Assistant Examiner(s): POTTER, ROY KARL
• Application Number:
  US08/681,688
• Time in Patent Office: 666 Days
• Field of Search: 257/778, 257/702, 257/725, 257/728
• US Class Current: 257/702
• CPC Class Codes: H01L 2223/6677 for antenna, e.g. antenna included within housing of semiconductor device antennas per se H01Q
• CPC Class Codes: H01L 2224/13111 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/81801 Soldering or alloying
• CPC Class Codes: H01L 23/66 High-frequency adaptations
• CPC Class Codes: H01L 24/81 using a bump connector
• CPC Class Codes: H01L 25/162 the devices being mounted on two or more different substrates
• 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 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01023 Vanadium [V]
• CPC Class Codes: H01L 2924/01029 Copper [Cu]
• CPC Class Codes: H01L 2924/01033 Arsenic [As]
• CPC Class Codes: H01L 2924/0105 Tin [Sn]
• CPC Class Codes: H01L 2924/01068 Erbium [Er]
• CPC Class Codes: H01L 2924/01074 Tungsten [W]
• CPC Class Codes: H01L 2924/01075 Rhenium [Re]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/10329 : Gallium arsenide [GaAs]
• CPC Class Codes: H01L 2924/1305 : Bipolar Junction Transistor [BJT]
• CPC Class Codes: H01L 2924/13064 : High Electron Mobility Transistor [HEMT, HFET [heterostructure FET], MODFET]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/1423 : Monolithic Microwave Integrated Circuit [MMIC]
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/19042 : being an inductor
• CPC Class Codes: H01L 2924/19043 : being a resistor
• CPC Class Codes: H01L 2924/19105 : in a side-by-side arrangement on a common die mounting substrate
• CPC Class Codes: H01Q 23/00 : Antennas with active circuits or circuit elements integrated within them or attached to them
• CPC Class Codes: H05K 1/0237 : High frequency adaptations H05K1/0216 takes precedence
• CPC Class Codes: H05K 2201/0175 : Inorganic, non-metallic layer, e.g. resist or dielectric for printed capacitor
• CPC Class Codes: H05K 2203/0315 : Oxidising metal
• CPC Class Codes: H05K 3/3452 : Solder masks

Abstract

A microwave/millimeter wave circuit structure supports discrete circuit elements by flip-chip mounting to an interconnection network on a low cost non-ceramic and non-semiconductor dielectric substrate, preferably Duroid. The necessary precise alignment of the circuit elements with contact pads on the substrate network required for the high operating frequencies is facilitated by oxidizing the interconnection network, but providing the contact pads from a non-oxidizable material to establish a preferential solder bump wetting for the pads. Alternately, the contact bumps on the flip-chips can be precisely positioned through corresponding openings in a passivation layer over the interconnection network. For thin circuit substrates that are too soft for successful flip-chip mounting, stiffening substrates are laminated to the circuit substrates. In a self-contained antenna application in which two of the circuit substrates are laminated together, with an antenna on one side and circuitry on the other side, a metallic ground plane between the substrates also serves a stiffening function.

Claims

1. A microwave/millimeter wave circuit structure, comprising:

a non-ceramic and non-semiconductor dielectric substrate,

an electrical interconnection network on said substrate, and

a plurality of discrete circuit elements flip-chip mounted to said substrate and electrically interconnected by said interconnection network, with spacings between the interconnected circuit elements compatible with electrical signals with wavelengths in at least part of the microwave/millimeter wave range,

said interconnection network comprising an oxidizing metal with an oxidized surface, and further comprising an array of non-oxidizing conductive pads on said oxidizing metal at the bump locations, with said bumps adhered to respective pads, said oxidizing metal comprising copper and said pads having a nickel/gold structure.

2. A microwave/millimeter wave circuit structure comprising:

a non-ceramic and non-semiconductor dielectric substrate,

an electrical interconnection network on said substrate, and

a plurality of discrete circuit elements, each of said plurality of discrete circuit elements being flip-chip mounted to said substrate with bumps including solder that electrically contact and mechanically adhere to and align with said interconnection network so that said discrete circuit elements are electrically interconnected by said interconnection network, with spacings between the interconnected circuit elements compatible with electrical signals with wavelengths in at least part of the microwave/millimeter range, wherein said dielectric substrate is less than approximately 600 micrometers thick, further comprising a stiffening substrate adhered to said dielectric substrate.

3. The circuit structure of claim 2, wherein at least some of said discrete circuit elements are electrically connected and mechanically adhered to said interconnection network by multiple reflowed solder bumps.

4. A microwave/millimeter wave circuit structure, comprising:

a non-ceramic and non-semiconductor dielectric substrate,

an electrical interconnection network on said substrate, and

a plurality of discrete circuit elements flip-chip mounted to said substrate and electrically interconnected by said interconnection network, with spacings between the interconnected circuit elements compatible with electrical signals with wavelengths in at least part of the microwave/millimeter wave range,

said structure comprising a transceiver circuit on a transceiver substrate, and further comprising an antenna substrate with an antenna formed on one side and adhered back-to-back with the transceiver substrate, said antenna communicating with said transceiver circuit through said substrates.

5. The circuit structure of claim 4, said and antenna substrate having a lower dielectric constant than said transceiver substrate.

6. A microwave/millimeter wave circuit structure comprising:

a non-ceramic and non-semiconductor dielectric substrate,

an electrical interconnection network on said substrate, and

a plurality of discrete circuit elements, each of said plurality of discrete circuit elements being flip-chip mounted to said substrate with bumps including solder that electrically contact and mechanically adhere to and align with said interconnection network so that said discrete circuit elements are electrically interconnected by said interconnection network, with spacings between the interconnected circuit elements compatible with electrical signals with wavelengths in at least part of the microwave/millimeter range, wherein said substrate is formed from a low-loss plastic material.