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SCM PREAMP & SENSOR Fabrication Readiness Review. P. Leroy. SCM Team. Block Diagram. S/C Location (1). +Y. -X. +X. -Y. SPACECRAFT DECK COMPONENTS. DSS. Mag boom (stowed). RF xnpdr. Battery. 3. 2. 4. C&DH. Navigator. 5. 1. USO. 8. SCM Pre-Amp. 6. DPU. 7. Star
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S/C Location (1) +Y -X +X -Y SPACECRAFT DECK COMPONENTS DSS Mag boom (stowed) RF xnpdr Battery 3 2 4 C&DH Navigator 5 1 USO 8 SCM Pre-Amp 6 DPU 7 Star Sensors PSEES Mag boom (stowed) FEEPS S-Band Antenna
S/C Location (2) AFG SCM SDP CEB EDI SDP AEB ADP INSTRUMENT DECK COMPONENTS (BOOMS DEPLOYED) SDP EDI SDP DFG
33mm 30mm 18mm Scope: Design Overview • Sensor (3 one axis sensors in a triaxial structure) • Primary coil • Secondary coil (feedback) • Preamplifier (3 analog channels, Power Supply Regulation + Calibration Buffer) • 1st level of amplification: Low Noise + Feedback • 2nd level of amplification +filtering • Calibration in flight from DSP Low Noise Preamplifier 46dB Amplification & Filtering 31.5dB B MMS Preamp packaging Vin Vout Feedback CAL From DSP
Action items since last review (CDR) • Gains have been adjusted to meet the resolution requirement • The preamp has been tuned with the EM4 sensors (4 mm ferrite cores). The sensitivity requirements are also satisfied now • Radiation Qualification of the commercial JFET finished, LAT also. Screening end 16 OCT 2010
SCM Sensor harness routed through the Spacecraft Deck Connectors: 15 pins DSub HD PCB mount (hard-mounted before soldering) 26 pins DSub HD crimp connector Surface treatments: Alodine 1200 Black Anodization Right Angle Vent Hole Ø 2mm FIELDS Preamp to Spacecraft Mechanical/Thermal ICD (101600016) Preamplifier Housing 3D+ Hybrid Module Screws (Stainless Steel) Cover (Al 2024 T851) Box (Al 7075 T7351) 4 spacers added in the corners of the 3D+ Hybrid (Epoxy+EC2216) for vibration hardness Ground lug connection Hole for Wire Thread Insert #8-32 x 1.5d
Fixtures • MICD 10160 0016 C • Preamp interface: 4x Ø3.99 mm with the following pattern • Fasteners provided by the S/C team
Parts status and 3D Module Manufacturing Flow • Revision 3 of the Detail Specification Document from 3D+ (3DPA2800) released and signed • All parts are in PIMS • Radiation memo written on the influence of total dose degradation and single event transients on the RH1013 OP AMP • JFET Radiation test report released by LPP sub-contractor (qualification successful) • 3 DPA done on all part references • Screening on the commercial parts (done prior to QM fabrication): • done on the 2 capacitors AVX LD103C225KAB and AVX LD10YC475KAB • JFET 404 (done on LOT2 for the QM flow, we have another lot, LOT1, in house, having passed LAT and Radiation Testing) • All other components are compliant with the ESA ESCC standard. No additional screening planned. • 2 component kits for the QM manufacturing • 1 QM deliverable • 1 backup kit • 9 component kits for the FM manufacturing • 4 FM + 2 SM + 2 LAT deliverable • 1 backup kit • Two lots of OP AMP RH1013, Lot 1: 67 parts, Lot 2: 20 parts (need 7 by 3D module).
JFET LS U404 Screening Issue • Status after the screening of 40 parts: • 1 part rejected after mechanical inspection • 4 parts rejected after C-SAM inspection (Scanning Acoustic Microscopy) • 13/14 datasheet criteria met after Burn-In (160h/125°C) except CMR (Common Mode Rejection) • Datasheet requirement is -95 dB or below for CMR • 3 parts OK, CMR < -95 dB (between -112 dB and -95.1dB) • 32 parts rejected, CMR > -95 dB (between -94.6 dB and -83 dB) • All parts have drifted • CMR not measured during LAT and Radiation Testing • Gain, Noise, Power Consumption and Polarization are the relevant parameters for our design, all were nominal and tested in SCM design configuration after LAT and Radiation Testing • CMR could have an influence on the Power Supply Rejection Ratio (not sure) • No functional risk expected. Only risk = PSRR degradation (if any)
PREAMP Stage 1 Common Mode Rejection is not driving the design B
Sensor Materials, Assembly Sequence and Processes Coil insertion in PEEK tube PEEK Tube Closed
SCM Adapter => Mag Boom ICD • SCM will be located at 4 m from the S/C and 1 m from AFG • Pigtail connector mounting on a bulkhead on the boom • Temperature measurement provided by a thermistor Doc. BTS Industrie, 046829 D ed00 Doc. James Sturm GSFC
SCM Triaxial structure fastening • Positioning before fastening + sliding at the interface => 4 countersunk screws, in titanium TA6V (change since CDR: no more PEEK fasteners considered) • FIELDS SCM to Spacecraft Mechanical/Thermal ICD (10160 0025 B), 3D update needed, slight modifications due to the use of PEEK 450CA30
Thermal Cycling on EM3 Sensor and X-Ray inspection reveal a weakness in the design Bepi Colombo sensors tested safely up to 200°C (and down to -180°C in June 2010) Ferrite core diameter smaller on MMS (3mm) than on Bepi Colombo (4mm) => Evolution for the QM, validated on EM4 Increase in diameter of the ferrite core to strengthen the sensors (less risk during manufacturing) Negligible added mass, same overall dimensions Material of the structure changed due to a problem of maturity revealed during procurement of bars and blocks PEEK 90HMF20 => PEEK 450CA30 Structure drawings updated Changes since CDR • Slight crack, very thin after the first thermal cycling of EM3 • Clearer after vibration at acceptance levels
QA Activities Status • Done • Configuration under control (Excel Configuration File) • SCM dedicated project documentation (all forms) • Manufacturers & suppliers defined • Manufacturing flowchart with all KIP/MIP (Mandatory/Key Inspection Points) • To be done • AIT documented (logbook filling…) • QM/FM fully under configuration: • 100% of our Items are identified by a drawing or a product ref. • Etching will be done at strategic locations on the main parts • Specific quantity is forecast for each model • Item Batch will be recorded in the configuration if any. • Materials & surface treatments controlled • Certificates of conformance will be provided • NCR, ECR, RFW/D will be followed in terms of each item • FM will be built as QM (including QM NCR preventive & corrective actions)
