10c-1 MAVEN IPER May 22-23, 2012 Particles and Fields Package Pre-Environmental Review May , c - Board Analysis Update Christopher Smith Mars Atmosphere and Volatile EvolutioN (MAVEN) Mission

10c-2 MAVEN IPER May 22-23, 2012 Board Analysis Responsibility Smith / UCB responsible for board and high dissipating part analysis on most boards GSFC did board and component temperature analysis for IIB. –Smith re-did the board  T analysis after board design changes but kept the GSFC part  Ts. BoardThermal SWIA Anode BoardSmith Preamp Board/MCPSmith Sweep HVPSSmith DigitalSmith LVPSSmith STATIC Anode BoardSmith Preamp BoardSmith TDC BoardSmith HV (15kV+MCP?)Smith Sweep HVPSSmith DigitalSmith Digital Daughter CardSmith LVPSSmith SWEA LVPSSmith DigitalSmith HVPSCESR PreampCESR AnodeCESR PFDPU BEBLASP DFBLASP MAG 1, 2 (MAD)GSFC DAP 1, 2Smith IIBGSFC / Smith IIB Daughter Card (ACHE)GSFC DCB 1, 2Smith DCB Daughter CardSmith REG 1,2Smith SEPDFESmith LPWPreAmpSmith

10c-3 MAVEN IPER May 22-23, 2012 Board Analysis Method Spreadsheet used to determine hottest board temp estimate –Dissipation, either centered or distributed, applied to board copper thickness. Assumed disk shape with diameter = to longest board dimension,  T 1 –Interrupted copper planes either conduct to their neighbors edge to edge or through overlaps,  T 2 –Conduction to board mounting surface calculated by screw pad overlap to thermal planes or via connection to thermal planes,  T 3 –Conduction to box body by screws or bonding with thermally conductive epoxy calculated,  T 4 –STATIC and SWIA are built with boards stacked on top of each other. For these an additional  T 5 was added from full box model in Thermal Desktop.

10c-4 MAVEN IPER May 22-23, 2012 Spreadsheet Example Copper Thermal Conductivity:390W/mK FR4 Thermal Conductivity:0.27W/mK Enter Values in Green Cells → Solder Thermal Conductivity:50W/mK Temperature Delta Across Planes of Copper (Centered Dissipation, Circular Plane Assumption) Include or Exclude From Total? Max Dimension of Board (in) Total Copper Thickness (oz) Max Dimension of Board (m) Copper Thickness (m) Inner Dissipation Radius Assumption (m) Single Conductance Value (W/C) # of Layers Total Conductance (W/C) Power Disipation (W)  T (C) Temperature Delta Across Planes of Copper (Distributed Dissipation,Circular Plane Assumption) Include or Exclude From Total? Max Dimension of Board (in) Total Copper Thickness (oz) Max Dimension of Board (m) Copper Thickness (m) Radius To Get Temperature (m) Single Conductance Value (W/C) # of Layers Total Conductance (W/C) Power Disipation (W/m 3 )  T (C) E E Edge Contact of One Plane to Another Plane Include or Exclude From Total? Length of Edge Contact (in) Gap (mil) Copper Thickness (oz) Length of Edge Contact (m) Gap (m) Copper Thickness (m) Shape Factor (m) Single Conductance Value (W/C) # of Layers Making Edge Contact Total Conductance (W/C) Power Disipation (W)  T (C) Sum of Two Paths Area Connection from One Plane to Another Plane Include or Exclude From Total? Area of Overlap (in 2 ) FR4 Thickness Between Copper (mil) Area of Overlap (m 2 ) FR4 Layer Thickness (m) Single Conductance Value (W/C) # of Same Overlaps Total Conductance (W/C) Power Disipation (W)  T (C)

10c-5 MAVEN IPER May 22-23, 2012 Max Board Temperature  T 1 → n are added to get an estimate for the hottest location on the board. Goal was to keep ∑  T n < 10 º C –Qual temp of box=50 º C so 50+10=60 º C for max predicted board temp –65 º C used for part stress analysis Interface Description Individual Conduction At Interface (W/K) Total Conduction At Interface (W/K)  T at Interface (C) Temperature Delta Across Planes of Copper (Centered Load) Temperature Delta Across Planes of Copper (Distributed Load) Edge Contact of One Plane to Another Plane Area Connection from One Plane to Another Plane Screw Pad Area Connection to Ground Plane Below Conduction Through Vias Bonded Area Connection of Board to Box Lip Screw Connection of Board to Box Using Area Screw Connection of Board to Box Using Screw Data Total to Board Mounting: Total to Board Mounting (other method for check): SWIA Board Mounting to Box  T: 5.1 Total  T: 9.2

10c-6 MAVEN IPER May 22-23, 2012 Component Temperatures All components dissipating 100 mW or more analyzed for each board. –In some cases lower dissipating parts were considered when grouped closely together. Theta J b used if provided –Calculated directly for simple parts. –Sometimes theta J c used in conjunction with calculated J c → b – Custom parts J c → b calculated using thermal imaging data and convection calculations Thermal images taken for all boards to make sure all high dissipating components were accounted for and behaving as expected. All resulted in individual component  Ts calculated at peak power.

10c-7 MAVEN IPER May 22-23, 2012 Board Temperature Margins Board Name Max Board Temp (C) Max Board Temp Margin (C) Max Component Temp (C) Max Component Derated Temp Limit (C) Max Component Temp Margin (C) Total Max Component Temp Margin (Board Margin + Component Margin) (C) SWIA Anode Board5312NoneN/A Preamp Board/MCP Sweep HVPS Digital578NoneN/A LVPS STATIC Anode Board588NoneN/A Preamp Board5213NoneN/A TDC Board HV (15kV+MCP?) Sweep HVPS Digital623NoneN/A Digital Daughter Card LVPS SWEA LVPS Digital PFDPU DAP 1, IIB DCB 1, DCB Daughter Card REG 1, SEPDFE5312NoneN/A LPWPreAmp : Component Heat Sunk to Box