1 SPP FIELDS MEP Main Electronics Package Preliminary Design Review Bill Donakowski UCB/SSL 13/14 NOVEMBER 2013 MAVEN PFDPU Flight Unit SPP MEP Baseline Design 13/14 NOV 2013 B. Donakowski SPP MEP Prototype Unit

MEP PDR Overview Requirements Challenges Design Overview Design Heritage Interlocking Frame Design Board Layout Control Drawing Daughter Board Details Connectors Fastening Thermal Design FEM Dynamics Analysis Vibration Testing Mass Properties Spacecraft Mounting Ongoing Issues 213/14 NOV 2013 B. Donakowski

MEP Functional Requirements Provide Packaging for 9 different Board Assemblies in common box – LNPS1, LNPS2, MAGo, MAGi, RFS/DCB, DFB, AEB (2x), TDS Modular box arrangement allows individual boxes to be built up independently and taken apart a/r Design/Coordinate/Fab Box Frames with responsible groups – UCB/MN/LASP/GSFC.060” thick Aluminum walls for Radiation Shielding One plane mounting interface to Spacecraft Adequate Structure Integrity (Strength, Dynamics) Optimal thermal path to Spacecraft Electrical Ground to S/C 313/14 NOV 2013 B. Donakowski

MEP Project Requirements Requirements per EDTRD, Analysis/Design – Materials selection, dynamics analysis, structural analysis, venting, EMI/EMC, grounding Testing/Verification – Mass Properties, Vibration, TVAC, Bakeout, Cleanliness 413/14 NOV 2013 B. Donakowski

MEP Challenges Provide common module for different boards Differing functions, connectors, and organizations (UCB/LASP/MN/GSFC) Box will be located in hot environment, must get heat out of box as much as possible (Thermal environment: baseline 65 C) Modular Frames must fit well together into final structural/thermal package All frames must be in-plane for proper interface to Spacecraft Panel Limited Mass Column Grid Arrays require conformance to Steinberg requirements (separation of first natural frequencies of PWB and structure) 513/14 NOV 2013 B. Donakowski

MEP Box Overview 6 Attach surface to Spacecraft Panel 13/14 NOV ” 6.85” 8.25” B. Donakowski 10 X #8 Fasteners 9 Individual Boxes

MAVEN Design Heritage 7 6x Skewers Top EMI Shield over Card- Card Harnesses S/C Bracket Box Vents Connectors on 3 sides of box MAVEN Electronics Box 11 Separate Cards sharing common Frame details Bolted to S/C Bracket on one Box face Box Size: 8.1” Wide x 6.2” Tall x 9.3” Long SPP FIELDS Electronics Box 9 Separate Cards sharing common Frame details Bolted to S/C on one Box face 10x Attach feet to S/C (every other Frame) #8 Fasteners (no shear panels) Box Size: 8.25” wide x 6.85” Tall x 10.0” long 2x Skewers Box Vents Connectors on 3 sides of box 13/14 NOV 2013 B. Donakowski 2 Shear Panels

MEP Typ Box Frame Assy 8 FrameInstrument Connectors EMI Shield Mounting Surface to Spacecraft Intrabox Connectors Screws and Custom Inserts at PCB perimeter Card PWB Daughter Board (DCB, DFB, TDS) 13/14 NOV 2013 B. Donakowski

Box Machined Frame Design 9 Box Frame walls.060” Multiple PCB attach screws to Frame to increase PWB stiffness and provide good thermal conduction path Machined 6061 T6 Al Alloy Machined Frame.85” Pitch (Frame to Frame) Feet for attachment to S/C 2 5-sided Framed Boxes (LNPS) 6X Skewers (#8 Threaded Rod) 13/14 NOV 2013 (OPEN) B. Donakowski 7 Open Framed Boxes Prototype Frame

Interlocking Frames Design 10 Individual Frames bolted together with 6X skewers Detail showing Frame Interlocking Features Each Box can be Pulled From Stack 13/14 NOV 2013 B. Donakowski

Electronics Board Layout Control Drawing 11 Drawing Maintained by UCB Distributed to Electronics Designers Controlling Document for Design Consistency between EE and ME aspects 13/14 NOV 2013 B. Donakowski

PCB Attach Method 1213/14 NOV 2013 Custom UCB designed insert Stainless Steel, Silver Plated Spiralock Threads provide Locking Device Insert soldered to PCB Traces UCB will provide to outside groups B. Donakowski

Daughter Board Details DB Module to be designed/built by SSL Large Chip (RJEX4000 CCGA) at Center Used on DCB, TDS, DFB 13 Custom threaded tool thru threaded inserts applies gentle force at corners to remove DB from MB 4X Custom Tools 13/14 NOV 2013 B. Donakowski Prototype Hardware

Connectors Fastening 14 UCB Custom Connector Nutplate Easier than nuts to assemble no need to get wrench to hold nuts during jackpost torquing Standoffs can be removed one-by-one D-Connector OTS Jackposts Spiralock tapped holes Desirement: Allow Jackposts to be Removed from outside of Box without opening box Material: 6061 T6 Aluminum 13/14 NOV 2013 B. Donakowski

Thermal Design S/C environment is hot—testing at 65 C Boards screwed to Frames at perimeter 2X Screws at PCB center to EMI shield w/ integral posts Attachment frame wet mounted to S/C (TBC) All Exterior Surfaces painted with electrically conductive Black Paint (Aeroglaze Z307) Black Anodize Interior Surfaces Alodine 600 Treatment at Box interfaces (to PCB, SC, other Frames) 15 S/C PCB screwed to EMI Shield (2x) 13/14 NOV 2013 B. Donakowski

Thermal Considerations: Center of PCB EMI Shield with integral posts to PCB provide conductive path from center of PCB Shield screwed to Frames at perimeter 16 Screws at perimeter to frame Integral Posts at Center (fastened to PCB) 13/14 NOV 2013 B. Donakowski

PWB Thermal Design Consider entire heat path Component To Board – All components dissipating more than 50 mW should be looked at by thermal engineer Thermal / Ground / Power Planes – Board dissipated power needs to travel to the frame via conduction in thermal (or ground) planes, then to the frame Board Mounting to Box – Need a good path from thermal planes to standoffs / box lip / wedge locks etc 2 Oz Copper Layers Layouts to be reviewed by thermal engineer 1713/14 NOV 2013 B. Donakowski

MEP FEM Dynamics Analysis Requirements – Project: MEP Box First Natural Frequency > 100 Hz Easy to achieve – Project: PWB First Natural Frequency > 150 Hz Analysis: 190 Hz – Steinberg Design: First Natural Frequency separation of 2X between individual PCB Assys and Entire Box (2 X 195 Hz = 390 Hz) 1813/14 NOV 2013 B. Donakowski

MEP FEM Dynamics Analysis 19 PCB/Spacers/EMI Shield Assy Fixed at Perimeters (to Frame) Fn=195 Hz Entire MEP Box Assy (PCBs/Frames) Fixed at Attach Feet (to S/C) Predict Fn > 500 Hz Preliminary FEM Runs Encouraging Fn > 100 Hz Separation of 2X between PCB and Overall Structure More detailed analysis required With completed LNPSs design Vibration testing of Prototype frames 13/14 NOV 2013 B. Donakowski

Vibration Testing 20 Vibration Testing Performed 01 Nov 2013 Sine Survey Performed – X Axis first mode: 376 Hz (perpendicular to PCBs) – Predict: > 500 Hz Prototype Hardware First Mode frequency Lower than FEM predicts Required 2X frequency separation close Further analysis required 13/14 NOV 2013 B. Donakowski

Mass Properties Current Estimate: Kg Continengency (20%): Kg Current Best Estimate: Kg – (Intrabox Cables included, S/C cables not included) 2113/14 NOV 2013 B. Donakowski

Spacecraft Mounting 22 +Y Interior Panel 13/14 NOV 2013 B. Donakowski

Ongoing Issues EMI shielding of cables on top of Box TBD – Separate Aluminum EMI Shield – Wrapping individual cables with proper shielding FEM – Verify adequate frequency separation between box structure and PWAs Further analysis and test required Continue coordination with outside groups design efforts – LASP/MN: PWA (Connectors, EMI Standoffs, Dynamics, Structural Properties) – GSFC: Box Frame (Interface Geometry to other Frames, Dynamics, Structural Properties) Grounding strap interface (APL to provide straps) 2313/14 NOV 2013 B. Donakowski