Low Cost, Lightweight, Inflatable

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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar
Applications Polymers for Lightweight/Affordable
Radar Workshop December 7-8, 2000 Len
Chorosinski Northrop Grumman Corporation Electroni
c Sensors Systems Sector 1745A West Nursery
Road - MS 368 Linthicum, MD 21090 410-993-1380
Fax [phone] leonard_g_chorosinski_at_mail.north
grum.com
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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications

• Overview
• Need
• Proposed Solution
• Project Objectives
• Technical Approach
• Antenna/Substrate/Membrane Design
• Large Scale Manufacturing
• Other Enabling Technology Needs
• Summary

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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications

• Need
• LEO satellite constellation for space-based radar
• Current antenna packaging is expensive and heavy
• rigid panels and hybridized T/R modules in
  hermetic enclosures
• current costs over 1M/m2 and weights over 22
  Kg/m2
• Future antennae are projected to be much larger
• from 40 m2 to 130 m2 to 200 m2
• Cost of launch vehicles alone may preclude
  deployment feasibility
• Need low cost, lightweight, stowable, large
  antennae

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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications

• Proposed Solution
• Fabricate the antenna on a flexible membrane that
  could be folded or rolled-up
• printed flex circuit technology
• Use inflatable structures to deploy the membrane
• already proven
• Use chip-on-board to eliminate heavy T/R modules
• hermeticity not needed for reliability
• integrate electronics into the antenna substrate
• multi-layer flex with buried passives

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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
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Inflatable JPL/ILC Dover SAR Antenna
Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications

• Project Objective
• Develop a low cost base-line process on
  lightweight flex substrate extendable to large
  scale manufacturing for mechanically conformal
  antenna array
• small scale 2 x 2 antenna array to demonstrate
  approach
• chip-on-board T/R chip set on backside of antenna
• Low cost goal less than 250K/m2
• Lightweight goal less than 6 Kg/m2
• Scalable to large size
• deployed size of 132 m2 (6 m x 22 m)
• Stowed size TBD

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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications

• Technical Approach
• Use liquid crystal polymer (LCP) for flex circuit
  substrate instead of Kapton (unsupported
  polyimide)
• 20 to 50 the cost of Kapton
• self-reinforcing uniform dielectric
• low dielectric constant of 2.9
• low loss suitable for high speed/high frequency
  applications, tan d 0.002
• low coefficient of thermal expansion
• substrate target is 5 to 8 ppm/C

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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications

• Technical Approach (continued)
• high strength
• tensile strength of 30 Kpsi
• tensile modulus of 1.3 Mpsi
• good adhesion to metals
• copper peel strength 6 pli
• very low moisture absorption (
• specific gravity 1.4
• projected weight estimate for the proposed
  flexible antenna substrate is about 2 Kg/m2

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What is Liquid Crystal Polymer (LCP)?
Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
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Liquid Crystal Polymers Have Rigid Segments Which
Tend to Align in Shear Flow
Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
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Biaxial Orientationis AchievedUsing
theCounter-RotatingDie
Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
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Uniaxial and Biaxial Orientation of LCPs
Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
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Producing LCP Filmswith In-Plane Isotrophy (CTE)
Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
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CTE of a 4 mil LCP Laminate as a Function of
Copper (1/4 Ounce)
Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
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Available LCP Films Already Tested
Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
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Laminate Material Cost Guide
Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
Cost Estimate Assumptions a) 18 in. x 24 in.
laminate with 1 oz copper on both sides. b)
Quoted quantities of 10-29 panels Note This
guides intent is to summarize information
related to widely used microwave material.
However, users are encouraged to obtain data
sheets and cost estimates, since both can change
periodically.
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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications

• Technical Approach (continued)
• Antenna Design
• simple 2 x 2 array 10 GHz demonstration
• printed slot-coupled patch radiators on front
  side
• integrated chip-on-board GaAs MMIC T/R chipset on
  backside
• Flip chip attach un-thinned coplanar GaAs MMICs
• lower cost than wire bond
• die cost is 50 to 70 of thinned GaAs MMIC
• assembly cost is 60 to 70 of wire bond
• twice the reliability of wire bonded assemblies
• superior performance
• lower parasitics than wire bond (6X improvement)

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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
Initial Flex Antenna and T/R Function Approach
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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications

• Use coplanar flip chip approach for basic T/R
  functions
• Switch, LNA, and PA at X-band

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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications

• Technical Approach (continued)
• Substrate Design
• work with Foster-Miller and HiDEC
• investigate candidate LCP materials for
  substrate(s)
• evaluate various lamination/assembly approaches
• ALIVH (Any Layer Inner Via Hole)
• conventional drilling and plating
• lay-up schemes for flexibility
• devise large scale manufacturing schemes
• interface with ILC Dover and/or LGarde
• inflatable space frame requirements

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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
Multi Layer Flex Stack-up
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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible Membrane
for Space-based Radar Applications
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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications

• Technical Approach (continued)
• Large scale manufacturing
• in-line reel-to-reel processing
• currently marketed by Phillips
• Sheldahl already using in-line technology
• currently with polyimide films but interested in
  LCP
• other manufacturers are also investing
• can be done in continuous or indexed fashion
• indexed can use existing equipment
• LCP film already produced in a continuous process

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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
1. Pattern All Layers
2. Laminate Layers Together
3. Print Solder Paste and Optical
Waveguide and Populate
Test
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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
Representative View of Flex Assembly
Radiating Elements
Long Flex
Devices
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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
Align and Attach Antenna Strips
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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
Attach to Inflatable Structure and Make Base
Connections
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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications
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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications

• Technical Approach (continued)
• Other enabling technology needs
• R-FLICS (Radio Frequency Lightwave Integrated
  Circuits)
• need small, flip chip modulators and detectors
• printed optical waveguides
• off-shoot of ink jet/solder jet technology
• Microjet printing by MicroFab Technologies
• initial tests successfully performed (with lossy
  material)
• power distribution chip
• low profile, high efficiency (90) DC-DC
  converter
• under development at Lucent/Bell Labs and others
• Fluidic Self-assembly (FSA)

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Low Cost, Lightweight, Inflatable Antenna Array
Development Using Flip Chip on Flexible
Membranes for Space-based Radar Applications

• Summary
• Develop the basic process parameters for LCP
  multilayer flex
• Address fundamental packaging issues
• radius of curvature, CTE, strength, etc.
• current handling, RF and DC losses,
  interconnection, etc.
• Fabricate simple demonstration vehicle 2x2
  subarray at 10 GHz
• Show scalablity to large area antenna
  manufacturing
• Basic technology is applicable to many military
  and commercial applications