1. Bill Donakowski Mechanical Engineer UCB/SSL billd@ssl.berkeley.edu
IDPU Chassis
Bill Donakowski
Mechanical Engineer
UCB/SSL

2. Mechanical Design and Development
IDPU Chassis
IDPU Chassis
Mechanical Design and Development
Bill Donakowski
Mechanical Engineer
UCB/SSL

3. IDPU Chassis Requirements
Functional
Provide Mechanical Packaging for 4 EFW electronic boards in one card cage box
BEB/DFB/DCB/LVPS Boards
Allow removal of each board layer separately
Provide structure and attachment to S/C
All access to test points following board installation into box
Structural
Positive strength margins
First natural frequency greater than 50 Hz
Radiation Shielding
External walls to have .35” equivalent thickness Aluminum
LOS requirement from outside to boards
Venting
Allow proper venting on ascent
Thermal
Survival Temperatures: °C to +60°C
Operational Temperatures: -25°C to +55°C
Mass
10 Kg Maximum
EMI Shielding
Provide metal shielding between each board layer (.030” thick aluminum)

4. IDPU Chassis Design Description
Standard electronics box/card-cage design
Approx. 6U format circuit boards (160mm x 230mm)
Similar to THEMIS
Aluminum 6061 T6 panels bolted together
gaps prevented at panel interface by step in edges
Separate layers for individual boards to slide into box
Each card layer consists of PCB, wedgelocks, connectors, and EMI shield
Cards held in place by wedgelocks on sides and fasteners on front panels
Each panel can be removed by unscrewing bolts, loosening wedgelocks, and sliding out
Separate, removable radiation shield over connectors and cables
Installed for testing and at integration to S/C
Aluminum 6061-T6
538

5. IDPU Chassis Overview 10” 7.5” BEB DFB 4.2” DCB LVPS 3.5”
TOTAL MASS: CBE 8.3 kg
7.5”
BEB
DFB
4.2”
DCB
LVPS
3 X VENTS
ALL CABLES TO S/C MATE TO FRONT OF BOX
3.5”
HOLES FOR BOLTING TO S/C PANEL #5 (9 X bolts)
REMOVABLE RADIATION SHIELD

6. IDPU Chassis Overview .030” THICK EMI SHIELD DFB CARD
WEDGELOCKS ON EACH BOARD EDGE
(manuf: CALMARK)
DFB CARD
EACH BOARD CAN BE REMOVED INDIVIDUALLY

7. IDPU Chassis Overview REMOVABLE RADIATION SHIELD
BACKPLANE ACCESS PANEL ALLOWS TEST POINT USE FOLLOWING BOARD INTEGRATION
REMOVABLE RADIATION SHIELD
(INSTALLED FOLLOWING BOX INTEGRATION ONTO S/C)
8 X ATTACH BOLTS (8-32)

8. RBSP Chassis Radiation Shielding
All external aluminum panels provide shielding
.35” thickness
Interlocking steps to prevent any gaps at connections
Removable Radiation Shield covers connectors and cables on front of box
Radiation Shield installs following box installation onto S/C
Provides .35” equivalent thickness radiation shielding line of sight to boards
.030” ALUMINUM EMI SHIELDS BETWEEN CARDS
VOLUME FOR CABLE RUN TO S/C

9. IDPU Chassis Radiation Scheme for Cables
Radiation LOS Maze allows simple cable runs
CABLE TIE BASES BONDED TO SIDE WALL
GLENAIR BACKSHELLS
.90”
CABLE RUN
PASS-THRU FOR CABLES

10. IDPU Chassis Structural Analysis
Assumptions/Tools
Limit Loads 100G
CosmoWorks FEM simulation
Results
Thick walled sections leads to robust structure
High strength margins throughout
Margin= (Strength/(LoadxSF)) - 1
Item
Mode
Margin
Attach Bolts to S/C
Shear
+2.1
Attach legs
Bending
+107
Screws holding Top Plate
Tensile
+30

11. IDPU Chassis Thermal Analysis
High power component heat-sunk directly to Chassis Frame
Amplifier Transistor 2N3637 on LVPS (one part)
All other electrical components mounted to PCB
Thermal path
Components Radiate to interior of IDPU Box
Conductive path from PCB > Wedgelocks > Chassis Frame
Exterior of IDPU Chassis radiates to inside of S/C
Chassis Lower Panel bolted to S/C panel
Components Junction Temperatures Analysis
Board Level Analysis performed on all Cards
Assumes hot PCB steady state (65°C) on all boards
Output junction temps compared with component limits
Lowest margin 14.2°C (SDRAM module on DCB)
Analysis performed by SSL (Chris Smith)

12. IDPU Chassis Thermal Treatments
EXTERNAL SURFACES BLACK KAPTON XC TAPE
BOX INTERIOR SURFACES GOLD ALODINE
BOTTOM PANEL GOLD ALODINE INTERFACE TO S/C PANEL INCORPORATES CHO-SEAL GASKET (PROVIDED BY APL)

13. IDPU Chassis Prototype Testing Completed
Complete build-up with Electronics
fit-check with all electrical cards
Verified grounding
Preliminary Vibration Testing
PCB dummies in lieu of actual PCB
Sine sweep
qualification random
First Natural Frequency 820 Hz
No issues to report
Vibration Qualification to take place on first Flight Unit as Protoflight

14. IDPU Chassis Design Changes from PDR
KA98 Backplane Connectors Replace DIN96
DIN96 Connectors Rejected by APL
All Boards and Mechanical Hardware changes completed
Electrical Layouts
Small changes based on electrical layouts
Keep-out zones, connector locations
Removable Radiation Shield
Added 2X attach feet (and bolts) to S/C
Removed gap below Shield (no longer cantilevers above S/C panel)
No other design changes from PDR
No Items from Peer Review

15. IDPU Chassis Drawing/Purchasing Status
Mechanical ICD, RBSP-IDP-MEC-500
Drawing completed
Submitted to APL 23-Sep-2009
Individual Board ICDs completed
Showing connectors, board geometry, keep out zones
All components laid out according to ICDs
Long Lead Items
CALMARK wedgelocks (10 weeks lead)
Ordered July 2009 (delivery: 01 Oct 2009)
Mechanical Parts Drawings
All detail part drawings and assemblies completed
All drawings released
Flight Fab
Drawings and RFQs sent out to machine shops for pricing
All Purchase Orders to be Placed Early October 2009

16. IDPU Chassis Flight Fab Flow
Build-Up of IDPU Card Cage
Receipt of Machined parts
Cleaning
Card Instl
PCB Coat and Stake
Electrical Checkout
Instrument Cal
EMC Testing
Qual Vibration Testing
Electrical Checkout
Qual TVAC Testing
Electrical Checkout
Apply Thermal Coatings
Weigh/Mass Props
Ship