Application of Conduction-Cooled PCBs and Composite Housing Materials in an Aerospace Electronic System

Transcription

1 Application of Conduction-Cooled PCBs and Composite Housing David L. Saums, Principal* DS&A LLC, Amesbury MA USA Robert A. Hay, Vice President, Business Development MMCC LLC, Waltham MA USA Subsidiary of Parker Hannifin Corporation Brian Edward, Senior Fellow and Systems Engineer RF Saab Defense and Security USA LLC, East Syracuse NY USA Peter Ruzicka, Sr. Mechanical Engineer Saab Defense and Security USA LLC, East Syracuse NY USA * Corresponding and Presenting Author IMAPS 23 rd Advanced Technology Workshop on Thermal Management Copyright 2014 DS&A LLC

2 Outline This presentation will describe: Part I: Development and results for a thermal constraining core material for use in highreliability, high density multilayer interconnect printed circuit board assemblies (PCBs), offering in a single material: a. Selectable coefficient of thermal expansion (CTE); b. Relatively high isotropic bulk thermal conductivity value; c. Reduced density d. Proven suitability for use in all standard PCB fabrication processes; Part II: Application of high-reliability PCBs fabricated using this PCB technology to mount multiple high heat flux RF semiconductors. Application of similar copper-graphite composite to manufacture a housing, providing heat transfer from the high-reliability PCBs to an ultimate heat sink. Application of cast copper-diamond composite inserts, cast in-situ into the composite housing material at specific locations, to which the highest dissipating packaged semiconductor devices are directly attached. Thermal modeling data for the devices, with demonstrated improvement in comparative thermal performance versus an identical housing manufactured from aluminum. Development of Cu-graphite composite as a thermal core for PCBs was presented here in Page 2 Copyright 2014 DS&A LLC

3 Part I Development of Constraining Core Thermal Materials for PCBs Page 3 Copyright 2014 DS&A LLC

4 Market Requirements -- Constraining Core Thermal Materials for PCBs Need: Single new material to replace heavy copper layer(s) for high-reliability PCBs as a constraining core thermal material for PCBs: Development of a thermal constraining core material for use in high-reliability, high density multilayer interconnect printed circuit board assemblies (PCBs), offering in a single material: a. Selectable coefficient of thermal expansion (CTE); b. Relatively high isotropic bulk thermal conductivity value; c. Reduced density d. Proven suitability for use in all standard PCB fabrication processes; Test program by a high-reliability PCB manufacturer to determine that all standard PCB fabrication processes per IPC 6012 can be met. Application of high-reliability PCBs fabricated using this PCB technology to mount multiple high heat flux RF semiconductors. Page 4 Copyright 2014 DS&A LLC

5 Existing PCB Materials and Constraining Core Thermal Materials Material Type CTE [ppm/ C, Room Temperature (typ.)] Thermal Conductivity (W/mK) Epoxy-coated E-glass Stablcor ST Cu-60Invar-20Cu 2 X-Y: 6.0 Z: 7.7 MMCC Cu-MetGraf Cu/50Mo/25Cu DuPont (Arlon) Thermount woven/nonwoven aramid with thermoset resins 1 X-Y: 175 Z: 1 X-Y: 164 Z: 22 X-Y: 287 Z: 225 X-Y: 268 Z: N/A Typical multilayer PCB Copper Aluminum Data sources: 1. J. Vesce, TTM Technologies, Inc., USA. 2. Pecht, M., Agarwal, R., McCluskey, F.P., Dishongh, T.J., Javadpour, S., Mahajan, R., Electronic Packaging Materials and Their Properties, CRC Press, Pergande, A., Rock, J., Advances in Passive PCB Thermal Control, Proceedings of the 2011 IEEE Aerospace Conference, Big Sky MT USA, March Rockwell Collins, Inc., USA. Page 5 Copyright 2014 DS&A LLC

6 Market Requirements -- Constraining Core Thermal Materials for PCBs Parameter or Property Goal or Requirement CTE Thermal Conductivity Density Young s Modulus Fabrication Manufactured Panel Size Manufactured Panel Thickness Manufactured Cost Availability Selectable, Lower value range appropriate for SiC, GaN Packaged or bare die Relatively high versus existing CTE-matched materials Requirement: > 250 W/mK Isotropic or near-isotropic if possible Reduced versus existing CTE-matched materials Requirement: 30+% reduction Relatively stiff, with reduced or no warpage in fabricated PCB Demonstrated compatibility with standard PCB fabrication processes (per IPC) Drop-in-place replacement of heavy copper layer Suitable for microdrilling, microvia processes Requirement: 30.5cm x 45.7cm (minimum) Initial requirement: 0.50mm (maximum) Stretch requirement: 0.25mm Reducible with future manufacturing process cost improvement program Suitable for IPC-standard PCB fabrication facilities globally Not subject to legislative restrictions Page 6 Copyright 2014 DS&A LLC

7 Solution: Constraining Core Thermal Materials for PCBs Result: The development program for a copper-graphite composite material manufactured in the required very thin sheets in large panel formats to achieve these goals was presented at La Rochelle in 2012 and 2013, as the program progressed. MMCC Cu-MetGraf -7 Copper-graphite composite sheet is now available in production in required 30.5cm x 45.7cm x 0.25mm thickness format. Several PCB manufacturing facilities have received prototype quantities and demonstrated compatibility with IPC 6012 fabrication process standard for PCBs. Initial programs and engineering design wins have been qualified for aerospace and defense procurement programs in the US. Page 7 Copyright 2014 DS&A LLC

8 Solution: Constraining Core Thermal Materials for PCBs Parameter or Property Goal or Requirement MMCC Cu-MetGraf Value CTE Thermal Conductivity Density Lower value range, appropriate for SiC, GaN Packaged or bare die Relatively high versus existing CTE-matched materials Requirement: > 250 W/mK Isotropic or near-isotropic if possible Reduced versus existing CTE-matched materials Requirement: 30+% reduction 7.0 ppm/ C Yes X-Y: 287 W/mK Z: 225 W/mK Near-isotropic 6.0 g/cc Young s Modulus Relatively stiff, with reduced or no warpage in fabricated PCB 75.8 GPa Fabrication Manufactured Panel Size Manufactured Panel Thickness Demonstrated compatibility, standard PCB fabrication processes Drop-in-place replacement of heavy copper layer Suitable for microdrilling, microvia processes Requirement: 30.5cm x 45.7cm (minimum) Initial requirement: 0.50mm (maximum) Stretch requirement: 0.25mm Yes Yes Yes Yes, demonstrated Yes, completed Yes, completed Manufactured Cost Reducible with future manufacturing process cost improvement program Yes, now underway Availability Suitable for IPC-standard PCB fabrication facilities globally Not subject to legislative restrictions Yes Yes Page 8 Copyright 2014 DS&A LLC

9 Solution: Constraining Core Thermal Materials for PCBs Result: A single new material to replace heavy copper layer(s) for high-reliability PCBs. Parameter or Property Molybdenum 1 Cu-Mo-Cu 1 CTE (ppm/ C) Thermal Conductivity (W/mK) Density (g/cc) X: 140 Y: Cu/60 Invar/ 20Cu 2 X-Y: 6.0 Z: 7.7 X-Y: 164 Z: 22 Cu-Graphite (Cu-MetGraf 7-300) 25Cu/50Mo/ 25Cu 2 Cu X-Y: 287 Z: 225 X-Y: 268 Z: N/A Young s Modulus (GPa) Notes: Constraining core materials for high-reliability PCBs. Sources: 1. Rockwell Collins Inc., USA; 2. Pecht, M., Agarwal, R., McCluskey, F.P., Dishongh, T.J., Javadpour, S., Mahajan, R., Electronic Packaging Materials and Their Properties, CRC Press, ISBN Page 9 Copyright 2014 DS&A LLC

10 Part II Application of Conduction-Cooled Constrained Core PCBs and Composite Aerospace Housing Page 10 Copyright 2014 DS&A LLC

11 Market Requirements Conduction Cooled Housing Need: Development and application of a conduction-cooled composite housing in an open-architecture format supporting commercially-available RF devices and thermal management technologies. mounting multiple high heat flux GaN RF devices Development of a commercially-sourced set of component RF devices will enable significant development and procurement cost reductions. Development of commercially-sourced constrained-core PCBs will enable cost reduction goals, eliminating traditional proprietary module packaging technologies. Use of CTE-matched commercially-available thermal management technologies enables: Limiting component operating temperatures to enhance system reliability and enable increases system availability with high performance devices Improvements in thermal management with CTE-matched materials for (a) component mounting and (b) local conduction cooling allows use of eutectic solder of GaN MMICs directly to Au-plated Cu-diamond composite inserts. Cu-diamond composite inserts transfer local device heat load to the transceiver base plate. Page 11 Copyright 2014 DS&A LLC

12 Solution: Conduction-Cooled Composite Housing with CTE-Matched Inserts Proposed: The same casting and finishing processes used to manufacture MMCC Cu- MetGraf -7 Copper-graphite composite sheet; Manufacture cast copper-graphite composite housing to support PCB; Incorporate high thermal conductivity, CTE-matched slugs cast within the composite housing at locations where high heat flux semiconductor devices would be located; Enable reduced procurement cost assembly. Page 12 Copyright 2014 DS&A LLC

13 Solution: Conduction-Cooled Composite Housing with CTE-Matched Inserts Proposed: Same casting and finishing processes as used to produce MMCC Cu-MetGraf -7 Copper-graphite composite sheet to be used to cast composite housing; GaN RF die mounted to pockets machined in surface of thermal core PCB. Plan View Exploded View Page 13 Copyright 2014 DS&A LLC

14 Solution: Conduction-Cooled Composite Housing with CTE-Matched Inserts Proposed: Same casting and finishing processes as used to produce MMCC Cu-MetGraf -7 Copper-graphite composite sheet to be used to cast composite housing; GaN RF die mounted to pockets machined in surface of thermal core PCB. Plan View Exploded View Page 14 Copyright 2014 DS&A LLC

15 Solution: Conduction-Cooled Composite Housing with CTE-Matched Inserts Proposed copper-graphite composite housing with copper-diamond inserts cast in-situ: Multi-channel electronics unit housing Cu-MetGraf Copper-graphite composite housing with Cu-Diamond Inserts Page 15 Copyright 2014 DS&A LLC

16 Solution: Conduction-Cooled Composite Housing with CTE-Matched Inserts Constrained-core PCB: Constrained-core PCB with Cu-MetGraf layers (2) and thermal vias for heat spreading and transport Page 16 Copyright 2014 DS&A LLC

17 Solution: Conduction-Cooled Composite Housing with CTE-Matched Inserts Proposed copper-graphite composite housing with copper-diamond inserts cast in-situ: Oversize Copper Metgraf Structure As-Cast Frame Structure Design Finished Frame Outline Copper Diamond Inserts Cross-section schematic of as-cast hybrid composite frame structure for composite housing Page 17 Copyright 2014 DS&A LLC

18 Solution: Conduction-Cooled Composite Housing with CTE-Matched Inserts Proposed: Same casting and finishing processes as used to produce MMCC Cu-MetGraf -7 Copper-graphite composite sheet to be used to cast composite housing; Copper-diamond composite inserts cast as mounts for high heat flux devices: Example of porous diamond particulate preforms manufactured via low pressure injection molding. (Gates and sprues will be removed and recycled prior to copper infiltration.) Page 18 Copyright 2014 DS&A LLC

19 Solution: Conduction-Cooled Composite Housing with CTE-Matched Inserts Copper-diamond composite insert manufacturing: Diamond preforms loaded into fiber preform Page 19 Copyright 2014 DS&A LLC

20 Solution: Conduction-Cooled Composite Housing with CTE-Matched Inserts CTE-matched copper-graphite composite housing manufacturing: Post-processing final machining steps for composite enclosure casting Finished back side of copper-graphite composite housing Page 20 Copyright 2014 DS&A LLC

21 Solution: Conduction-Cooled Composite Housing with CTE-Matched Inserts Composite copper-graphite housing (copper-diamond inserts) and constrained core PCB: Highest heat flux GaN RF devices mount directly through window in PCB to the copper-diamond inserts in enclosure casting: Heat transport from the high power components into the copper MetGraf housing, immediate spreading by the copper-diamond Inserts, and removal by the array structure. Page 21 Copyright 2014 DS&A LLC

22 Solution: Conduction-Cooled Composite Housing with CTE-Matched Inserts Thermal model results for the copper-graphite housing and copper-diamond inserts. Temperature at the GaN device mounting interface is 59.6 C: Example of thermal model for reference copper-graphite housing Page 22 Copyright 2014 DS&A LLC

23 Solution: Conduction-Cooled Composite Housing with CTE-Matched Inserts Thermal model results for a reference aluminum housing. Temperature at the GaN device mounting interface is 70.7 C: Example of thermal model for reference aluminum housing Page 23 Copyright 2014 DS&A LLC

24 Solution: Conduction-Cooled Composite Housing with CTE-Matched Inserts Thermal modeling shows the following comparative results: Parameter or Property Aluminum Housing (Reference) Cu-Graphite Composite Housing w/cu-diamond Inserts Temperature at GaN device mounting interface ( C) Page 24 Copyright 2014 DS&A LLC

25 Solution: Conduction-Cooled Composite Housing with CTE-Matched Inserts CTE-matched copper-graphite composite housing manufacturing: Post-processing final machining steps for composite enclosure casting Machining cavity side of copper-graphite housing Finished multichannel electronics unit housing manufactured as a cast copper-graphite composite with in-situ copper-diamond inserts. Page 25 Copyright 2014 DS&A LLC

26 Result: Conduction-Cooled Composite Housing and CTE-Matched Inserts Composite housing and inserts: Manufactured with the same casting and finishing processes Comparison of material properties Parameter or Property Cu-Graphite Composite 1 Copper Diamond Composite 2 Cu-MetGraf CuDia 65 CTE (Average in-plane, C) (ppm/ C) Thermal Conductivity (W/mK) X-Y: 7.0 Z: 16 X-Y: 287 Z: 225 X-Y: 7.5 Z: Z: 550 Density (g/cc) Material applications: 1. Constraining core layer for high-reliability PCB fabrication and for manufacture of CTE-matched system housing; 2. High thermal conductivity inserts for high heat flux device mounting locations. Page 26 Copyright 2014 DS&A LLC

27 Result: Conduction-Cooled Composite Housing with CTE-Matched Inserts Successful design and prototype manufacturing of conduction-cooled CTE-matched copper-graphite enclosure housing; Initial thermal modeling results show the thermal design advanced on this program reduces the GaN device operating temperature in excess of 10 C. Thermal performance improvements result in: Reduction in power amplifier operating temperature in excess of 10 C. This temperature reduction yields an order of magnitude (10X) amplifier MTBF increase Accomplishes attendant performance improvements with respect to RF device and system output power, efficiency, and gain. Current work indicates system-level cost improvements: a. Unit production costs will be reduced on the order of 50%; b. Active array operation and maintenance costs, which are ultimately even more significant, can be reduced up to 50% also. c. Overall improvement in development and Life Cycle Cost structure. Next steps: Manufacture and assembly of complete test array for empirical data collection and system performance analysis. Page 27 Copyright 2014 DS&A LLC

28 Notes DuPont is a registered mark of E.I. du Pont denemours and Company. MetGraf and Cu-MetGraf are trademarks of MMCC LLC, Waltham MA USA Website: Stablcor is a registered mark of Stablcor Technology Inc., Huntington Beach CA USA Website: Thermount is a trademark of E.I. du Pont de Nemours and Company. Page 28 Copyright 2014 DS&A LLC

29 References 1. Future Trends in PCB Technologies for Space Applications, ESA PCB Workshop, October ESTEC, Noordwijk, The Netherlands. 2. Hay, R., Copper MetGraf Composites for Printed Circuit Board Thermal Control, IMAPS Advanced Technology Workshop on Thermal Management 2011, Palo Alto CA USA, November 7-9, IPC 6012(C) Qualification and Performance Specification for Rigid Printed Circuit Boards, ISBN , April Published by IPC, Bannockburn IL USA, 4. Pecht, M., Agarwal, R., McCluskey, F.P., Dishongh, T.J., Javadpour, S., Mahajan, R., Electronic Packaging Materials and Their Properties, CRC Press, ISBN Pergande, A., Rock, J., Advances in Passive PCB Thermal Control, Proceedings of the 2011 IEEE Aerospace Conference, Big Sky MT USA, March 2011, Manuscript / Saums, D., Developments in CTE-Matched Thermal Core Printed Circuit Boards, Electronics Cooling Magazine, June 2011, pp Soulier, J.-Y., C-PCB: A EURIPIDES Initiative for Evaluating Carbon-drained Printed Circuit Boards for Airborne Applications, EURIPIDES Forum, Berlin, Germany October, Vasoya, K., Burch, C., Roy, D., Solving Thermal and CTE Mismatch Issues in Printed Circuit Boards and Substrates, Proceedings, IMAPS Symposium 2005, Philadelphia PA USA, September 25-29, Page 29 Copyright 2014 DS&A LLC

30 Contact Information DS&A LLC David L. Saums, Principal Chestnut Innovation Center E: 11 Chestnut Street Tel: Amesbury MA USA Website: Business and product development strategy for electronics thermal management: advanced thermal materials, components, and thermal systems. MMCC LLC Robert A. Hay, Vice President Business Development 191 Clematis Avenue E: Waltham MA USA Tel: Website: MMCC is a subsidiary of Parker Hannifin Corporation Metal matrix cast composite design, development, and series production on a design-to-print basis for commercial, industrial, and military/aerospace markets. Saab Defense and Security USA LLC Brian Edward, Senior Fellow and Systems Engineer RF 5717 Enterprise Parkway E: brian.edward@saabusa.com East Syracuse NY USA Tel: Pete Ruzicka, Sr. Thermal Engineer E: peter.ruzicka@saabusa.com Page 30 Copyright 2014 DS&A LLC