MRB on SLAC Flex Cables for Tower 4

MRB, Tower 4 Flex Cables Bad Coupons & NCRs SLAC NCR TBD: 

MRB, Tower 4 Flex Cables Bad Coupons & NCRs SLAC NCR TBD Dave Rich March 24, 2005

1. Description of Non-Conformance: 

1. Description of Non-Conformance C2-008 Flex Cable Assembly is made from the Flex Lay-up Part number LAT-DS-00724 Serial Number 0050 As shown on EC50219 coupon had several internal annular rings shorter than the required minimum of 0.0020 inches. (Ref. photo on slide #7) C6-002 Flex Cable Assembly is made from the Flex Lay-up Part number LAT-DS-00728 Serial Number 0038 As shown on EC 40514 SN 39 had several separations between barrel plating and internal layers in ‘as received’ microsection (Ref. photo on slide #8)  Both cables have been fully functionally electrically tested Functional tests consist of register and data readout tests and trigger request test as described in LAT-PS-04643 (Tracker Flex Cable Functional Test Produce) to confirm the communication capability between TEM (Tower Electronics Module) and TMCM (Tracker Multi-Chip Module).

1. Description of Non-Conformance: 

1. Description of Non-Conformance C0-021 Flex Cable Assembly is made from the Flex Lay-up Part number LAT-DS-00584 Serial Number 0088 (passed GSFC coupon testing) NCR #392: The J6 connector is slightly split between several connector pins. Damage occurred at SLAC during demating of connector saver. Inspection performed, connector structure not significantly degraded. NCR needs to be formally dispositioned and closed prior to shipment. Procuring connector demate tool to prevent recurrence. C4-010 Flex Cable Assembly is made from the Flex Lay-up Part number LAT-DS-00726 Serial Number 0056 (passed GSFC coupon testing) NCR #320: Large crease in the main body of the flex cable observed during incoming Inspection. Cable passed electrical tests. SLAC dispositioned Cable “scrap” based on observation. RTV for inspection and replacement. Parlex takes exception to our disposition. Parlex claims cable does not meet rejection criteria. Cable returned to SLAC. Parlex apparently rolled or “fixed” the crease. Crease is not hardly apparent. Recommend retest of C4-010. Pending successful test (anticipated) disposition “use-as-is”. NCR needs to be formally dispositioned and closed prior to shipment.

3. Suspected Root Cause: 

3. Suspected Root Cause Suspected root cause: C2-008 Flex Cable Assembly: Root cause is due to mis-registration of the layers during lay-up. C4-010 Flex Cable Assembly: Suspected root cause of the failed coupons is the failure to water blast the vias before plating to remove foreign material and contaminants 4. Impacts to Inventory Approximately 50% of the cables produced before February had bad coupons The next replacement Parlex shipments is scheduled for C2 Parlex shipment is scheduled for 4/4 C4 Parlex shipment is scheduled for 4/7 C6 Parlex shipment is scheduled for 4/6 Waiting for new cables would incur at least 2 week delay in the assembly of Tower 4

5. Corrective Action: 

5. Corrective Action Misregistration: MATCHING LAYERS PRIOR TO LAMINATION SCALING OF ARTWORK VERSUS OFFSETS AT DRILL (OLD) DRILLING IN TWO ZONES WITH ONE PIN SET-UP (NEW) DRILLING IN TWO ZONES WITH TWO PIN SET-UPS Separation: Process changes at the manufacturer (water blasting) have now been implemented. Split Connector: Implement demate tool

Slide6: 

Misregistration: SCALING SHOWING CONSISTANNT AND REPEATABLE RESULTS EFFECTIVENESS MEASURED AT DRILLING: EXCELLENT RESULTS Separation: Of 8 cables tested that were produced with water blasting, none showed separation of barrel plating and internal layers. Split Connector: Demate tool effective, used at Parlex 6. Effectiveness of Corrective Action

7. Recommended Disposition: 

7. Recommended Disposition Generate an NCR and maintain NCR until these Flex Cables have passed Tower level Vibe and Thermal Vacuum Environmental Testing. There is only one "failed coupon" Flex Cable on any side of the Tower.  Therefore, we still have a redundant (good coupon) Flex Cable on all sides of Tower 4.

8. Backup Slides: 

8. Backup Slides Cross sectional view of a plated through hole showing inadequate internal annular ring. SN 050, etched, (200X)

8. Backup Slides: 

8. Backup Slides Cross sectional view of a plating through hole showing separation between barrel plating and internal layer. SN 37-39, ‘as received’, unetched, (200X)

8. Backup Slides: 

8. Backup Slides Flex Cable Status on Towers