Method for manufacturing a high-performance package for monolithic microwave integrated circuits

• US 5,023,993 A
• Filed: 12/19/1989
• Issued: 06/18/1991
• Est. Priority Date: 09/30/1988
• Status: Expired due to Fees

• Current Assignee: Grumman Aerospace Corporation (Northrop Grumman Corporation)
• Original Assignee: Grumman Aerospace Corporation (Northrop Grumman Corporation)
• Inventors: Fengelly, Raymond S.
• Primary Examiner(s): Echols, P. W.
• Assistant Examiner(s): Bryant, David P.
• Application Number:
  US07/452,308
• Time in Patent Office: 546 Days
• Field of Search: 29/825, 29/837, 29/840, 29/843, 29/851, 29/852, 29/853
• US Class Current: 29/843
• CPC Class Codes: H01L 23/66 High-frequency adaptations
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H01P 1/2039 Galvanic coupling between Input/Output
• CPC Class Codes: H01P 5/085 Coaxial-line/strip-line transitions
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing
• CPC Class Codes: Y10T 29/49144 by metal fusion
• CPC Class Codes: Y10T 29/49149 by metal fusion bonding
• CPC Class Codes: Y10T 29/49163 with sintering of base

Abstract

The present invention incorporates a specially-designed low-pass filter into the feedthrough of a monolithic microwave integrated circuit (MMIC) to provide compensation for discrepancies from the impedance required for an MMIC package to be matched to a transmission line. The compensation allows all parameters to be adjusted and the complete filter to be printed.

The main features of the invention include minimum width for the under-wall conductor and brazing metallization, two open-circuited stubs at the package-die interface for wire bonding ease, and metal-filled vias connecting the ground plane base and the lid sealing ring to bring the lid sealing ring to RF ground.

The present invention also includes a method for designing the desired feedthrough the obviates the need for scale-model feedthrough design before printing, a prior art method that requires precision in the scale model. An electrical model of a feedthrough is first derived. The electrical model is then adjusted according to the parameters desired for a new, compensated feedthrough using any known method, including software such as touchstone. Finally, the new feedthrough is fabricated based upon the adjusted electrical model.

Claims

1. A method for manufacturing a monolithic integrated circuit package having a perimeter, comprising the steps of:

(a) printing at least one feedthrough on a first surface of a ceramic substrate having first and second opposed surfaces;

(b) firing the ceramic;

(c) forming a plurality of visa in the ceramic substrate, each said via extending from said first surface to said second surface;

(d) cutting a die cavity in the ceramic for each package to be formed so that each via is located at a point distant from both said die cavity and the perimeter of each said package;

(e) metallizing at least one electrical conductor on the ceramic substrate, each said electrical conductor corresponding to a printed feedthrough;

(f) metallizing the vias; and

(g) brazing a ground plane base to the ceramic substrate on a second surface opposite said first surface.

2. A method for manufacturing a monolithic integrated circuit package as claimed in claim 1, further comprising the step, after step (f), of:

(f'"'"') cutting the ceramic substrate into individual packages.

3. A method for manufacturing a monolithic integrated circuit package as claimed in claim 1, further comprising the step of:

(h) welding a lead to each metallized feedthrough.