GLAST Large Area Telescope: Electronics, Data Acquisition & Flight Software W.B.S 4.1.7

1. Gamma-ray Large Area Space Telescope GLAST Large Area Telescope: Electronics, Data Acquisition & Flight Software W.B.S 4.1.7 Analysis of cPCI Backplane Connector Assembly xray’s Gunther Haller haller@slac.stanford.edu (650) 926-4257

2. Backplane Analysis • Method: give following information for each backplane • Starting point: list of pins supplied by GSFC identified as under-fill • Identify pins in that list which are not used • Pins already identified on SLAC’s spread-sheet • Pins not on the spread-sheet • There is no reason to spend time discussing the fill of any pins not used anyways • Of the remaining pins, list of pins used • Pins already identified on SLAC’s spread-sheet • Pins not on the spread-sheet • Discuss fill of both

3. Notes (1) • Number of pins soldered on backplane excluding shield-pins (which are not used and thus ignored) • P1: 25 rows • P2: 22 rows • P3: 19 rows • P4: 25 rows • P5: 22 rows • Each row: columns Z, A, B, C, D, E, F • Z and F are shield pins, not used • Total number of pins potentially used • 113 x 5 = 565 for each slot, times 4 slots = 2,260 pins • Identification of 4 slots • X1: CPU (3u-card in P1, P2) • X2: CPS (3u-card in P4, P5) • X3: SIB (6u-card in P1-P5) • X4: LCB (6u card in P1-P5) • Connectors not used for flight • X1: P3, P4, P5 • X2: P1, P2, P3 • X3: P2, most of P3 • (P3 only uses: A19 (dclk); A1-E1 (gnd); A5-E5: (3.3V); B8-B14 (gnd); gnd and 3.3V redundant on other connectors) • X4: P2, P3 • Following connector are used for EGSE only, thus ignored for flight crates • X1: P4/P5 holds custom Serial card, not used/integrated for flight • X2: P1/P2 holds commercial Ethernet card, not used/integrated for flight

4. Notes (2) • Comment to intentionally shorted shield pins (3 pins on row Z or row F) apparent on some xrays • Mostly, center pin identifies row in which pin was to be touched-up • Wanted some kind of indication that correct pin was in fact touched-up just in case that no change might be apparent before/after touch-up • Shorts were removed after xray but before QA, although shorts would have no effect since • Shield pins already shorted to each other via board/connector • LAT does not use shield pins anyways

5. First Flight Backplane 2414 • Total of ~ 2,000 pins looked at in xray • 22 pins identified on GSFC list • Not used (16 pins) • Already identified on SLAC list • X1: P5-D11; P5-C12; P5-D12; • X2: P1-B17 • X3: P1-B17 • Not used from remaining identified (X1-P5, X2-P1 not used as stated) • X1: P5-E11 • X2: P1-A19 • X2: P2-C10, B11, C11, D11; P4-C6 • X3: P1-B2 ; P1-B6 (red+5); P5-B2 (ch-gnd); P5-C14 (red+5), P4-B21 (redGND); • X4: P5-B5 (red+3.3) • Used • Already identified on SLAC list • X1: P1-B15 (Frame#); • X3: P1-A7 (AD30); • Not on SLAC list • X1: P1-C23 (AD3) ; • X3: P1-D16 (stop_n)

6. Second Flight Backplane 2415 • Total of ~ 2,000 pins looked at in xray • 18 pins identified on GSFC list • Not used • Already identified on SLAC list (7 pins) • X2: P1-B3; P4-A15; P4-B23; • X3: P1-B8; P2-C12; J4-C1, J4-C16 • Not used from remaining identified • X1: P1-A19 (3.3V, one of 7 pins, not needed) • X3: P2-B12; P3-C1 (red+5), C3 (red+5), E4 • X4: P1-B1 • Used • Already identified on SLAC list • X4: P1-C23(AD3); P4-C11(EI_PRIM_5_N); P4-C21(EI_PRIM_2_P) • Not on SLAC list • X1: P1-B19 (AD15), P1-A20 (AD12) ;

7. Third Flight Backplane 2420 • Total of ~ 2,000 pins looked at in xray • 5 pins identified on GSFC list • Not used • Already identified on SLAC list • None • Not used from remaining identified • X1: P2-C21 • X2: P1-D25 • X3: P2-E8, B13 • X4: P5-C22 • Used • none

8. Fourth Flight Backplane 2418 • Total of ~ 2,000 pins looked at in xray • 17 pins identified on GSFC list • Not used • Already identified on SLAC list • None • Not used from remaining identified • X1: P2-B5, P4-E7, D8, E8, D9 (P4 not used) • X2: P1-D11, B23, B24, C24; P2-B1, C1; (P1, P2 not used) • X2: P4-C9 (red+5); P5-A5 (red-28) • X4: P5-D21 • Used • Already identified on SLAC list • None • Not on SLAC list • X1: P2-B6 (GBM RDNT) • X3: P1-E7 (AD27)

9. Fifth Flight Backplane 2419 • Total of ~ 2,000 pins looked at in xray • 6 pins identified on GSFC list • Not used • Already identified on SLAC list • X1: J5-C13, B15 • Not used from remaining identified • X1: P5-C15, A18 (X1-P5 not used) • X3: P2-D10 • X4: P2-A10 • Used • none

10. First Flight Spare Backplane 2416 • Total of ~ 2,000 pins looked at in xray • 46 pins identified on GSFC list • Not used • Already identified on SLAC list (17) • X1: P2-C10 • X2: P1-D11, A17, D19, A21 (P1 not used as indicated) P1-D11, A17, D19, A21 (X2 not used as indicated); P5-B6, C6 (redundant as indicated) • X3: P3-A4, B4, C5, D5, D6 (P3 not used as indicated) • X4: P3-E10 • Not used from remaining identified • X1: P2-B12, B13, C21 • X2: D25 (gnd red) • X3: P2-A7, B7, A8, B8; P4- D24 (not used), C25(gndred), D25 (not used); • X4: P2-B18, C18; P4-D6 (not used), • Used • Already identified on SLAC list • None • Not on SLAC list • X2: P4-D2 (PRIM_SPO1_P), D3 (PRIM_SPO0_N), C25 (CLK_OUT_PRIM_P), P5-D2 (SPARE_TO_LCB_0), B21 (28V_RET), D21 (SPI_PRIM_RDNT_SEL) • X3: P1-A22 (AD7); P4-D20 (SC_RDNT_PWR_PDU_RDNT_SEL), P5-A19 (PRIM_1553_P) • X4: P4-C23 (EI_PRIM_1_P); P5-D1 (GND)

11. Summary • 5 Flight boards (2414, 2415, 2420, 2418, 2419) • > 10,000 pins checked • 68 pins called out by GSFC as questionable • Of those 14 were already on SLAC spread-sheet identified as not used • 54 pins remaining • Of those 42 are not used (no need to discuss fill) • Remaining are 11 pins to examine (of those 6 were on SLAC list) • Next pages show all 11 pins • 1st flight spare (2416) • 46 pins called out by GSFC as questionable • Of those 42 are not used (no need to discuss fill) • Remaining are 11 pins to examine • Next pages show all 11 pins

12. Flight

13. X-ray of pins 2414: X1-P1-B15 Void a bit bigger than on one of the previous cross-sections shown below. Would estimate that to be about 75% fill and the pin on the right to be at least 65% GLAT2414 X1 P1 B15 FRAME#

14. X-ray of pins 2414: X1-P1-C23 Fill ~ 75%, based on simple ratio of 3 out of 4 shows solder fill. GLAT2414 X1 P1 C23 AD3

15. X-ray of pins 2414: X3-P1-A7 Fill >80%, assuming 5 out 6 ratio filled. GLAT2414 X3 P1 A7 AD30

16. X-ray of pins 2414: X3-P1-D16 Fill ~ 80%, based on simple ratio of 3.5 out of 4.5 shows solder fill. GLAT2414 X3 P1 D16 STOP_N

17. X-ray of pins 2415: X1-P1-A20 80% fill based on 4.5 out of 5.5 fill ratio. GLAT2415 X1 P1 A20 AD12

18. X-ray of pins 2415: X1-P1-B19 >90% fill. GLAT2415 X1 P1 B19 AD15

19. X-ray of pins 2415: X4-P1-C23 65% fill based on 2 out of 3 fill ratio. GLAT2415 X4 P1 C23 AD3

20. X-ray of pins 2415: X4-P4-C11 >70% fill assuming 2.25 out of 3 fill ratio. Summed voids to get to 0.75 voids. GLAT2415 X4 P4 C11 EI_PRIM_5_N

21. X-ray of pins 2415: X4-P4-C21 80 % fill assuming 2.4 out of 3 solder fill. GLAT2415 X4 P4 C21 EI_PRIM_2_P

22. X-ray of pins 2418: X1-P2-B6 70 % fill assuming 4 out of 5.5 solder fill. GLAT2418 X1 P2 B6 GBM RDNT

23. X-ray of pins 2418: X3-P1-E7 65 % fill assuming >3 out of 5 solder fill. GLAT2418 X3 P1 E7 AD27

24. Flight Spare

25. X-ray of pins 2416: X2-P4-D2 80 % fill assuming 4 out of 5 solder fill. GLAT2416 X2 P4 D2 PRIM_SPO1_P

26. X-ray of pins 2416: X2-P4-D3 75 % fill assuming 4.5 out of 6 solder fill. GLAT2416 X2 P4 D3 PRIM_SPO0_N

27. X-ray of pins 2416: X2-P4-C25 90 % fill. GLAT2416 X2 P4 C25 CLK_OUT_PRIM_P

28. X-ray of pins 2416: X2-P5-D2 75 % fill assuming 4.5 out of 6 solder fill. GLAT2416 X2 P5 D2 SPARE_TO_LCB_0

29. X-ray of pins 2416: X2-P5-B21 80 % fill assuming 5 out of 6 solder fill. GLAT2416 X2 P5 B21 28V_RET

30. X-ray of pins 2416: X2-P5-D21 80 % fill assuming 5 out of 6 solder fill. GLAT2416 X2 P5 D21 SPI_PRIM_RDNT_SEL

31. X-ray of pins 2416: X3-P1-A22 > 65 % fill assuming 4 out of 6 solder fill. GLAT2416 X3 P1 A22 AD7

32. X-ray of pins 2416: X3-P4-D20 70 % fill assuming 3.5 out of 5 solder fill. GLAT2416 X3 P4 D20 SC_RDNT_PWR_PDU_RDNT_SEL

33. X-ray of pins 2416: X3-P5-A19 >65 % fill assuming 4 out of 6 solder fill. GLAT2416 X3 P5 A19 PRIM_1553_P

34. X-ray of pins 2416: X4-P4-C23 >65 % fill assuming 3 out of 5 solder fill. GLAT2416 X4 P4 C23 EI_PRIM_1_P

35. X-ray of pins 2416: X4-P5-D1 70 % fill assuming 4 out of 5.5 solder fill. GLAT2416 X4 P5 D1 GND

36. Conclusion • All boards were conformal coated a while ago • The boards are at different stages in assembly • Touching up boards now will require stripping off some conformal coat (not difficult) • Flight • 2414: 4 pins ok • 2515: 5 pins ok • 2420: no issues • 2418: 2 pins ok (might touch these up, but no great hope of improvement) • 2419: no issues • Flight spare • 2416: 11 pins. Looks ok although we will try to touch up several of those pins. • In summary although fill is not ideal and what we would like, it is acceptable considering all other constraints • Qual testing of example boards (using short-open tests) did not show any issue even with pins filled down to 30% fill. • TC/Vib/Thermal-vacuum did not show any issues on the proto-flight SIU crate (with flight assembled SIB/CPS/LCB/CBP/RAD750) and those boards had more voids and underfill than the above flight backplanes)