DK Log Book Started April 2025 ----------------------------------- The most recent entries appear first in this log book. ----------------------------------------------------------------- DATE: -Apr-2025 Topic(s): ----------------------------------------------------------------- DATE: 14,15-Apr-2025 Topic(s): Analog Input Section Shield Cover Had a brief meeting with Nathan and topics included the Shield Cover for the PMT Analog Input Section. We need 40 of these soon for the first build of DK Boards. The PMT ADC is one of the higher power consumming parts on the board and it does not have a center thermal pad (like e.g. the Timing Generator) so we are concerned about its Si Temperature with zero air circulation in the module. The intent is to allow the Analog Input Section Shield Cover to also function as a Heat-Sink for the PMT ADC. The upper surface of the PMT ADC is only about 1.32 mm above the top surface of the DK PCB where as in the Analog Input Section the distance between to top surface of the PCB and the bottom surface of the Shield Cover will be beteen about 6.0 and 7.5 mm. Thus the Shield cover really needs to be a 3D part or it needs to have a 4.7 to 6.2 mm thick boss added to it over just the PMT ADC. The size of the PMT ADC is nominally 9.0 mm x 9.0 mm and recall that it is a 0.8 mm pitch BGA. The height of the components that immediately surround the PMT ADC is yet to be determined wrt the 1.32 mm seated height of the ADC itself. There is about 14 mm in the East-West direction between the East edge of the ADC and the West edge of the closest 6 mm tall Transformer - so there is space available to include a step in the otherwise flat Shield Cover (but we may need a boss because of the heigth of comps that surround the PMT ADC. Look at the Thermal Interface Materials. Start by looking at 3M. Their stuff is probably high quality but it is complete confusion because I think much of it is in bulk and ment for consumer die cutting. There is also interesting stuff from NASA about this whole topic and how to do it right. The AD9083 PMT ADC is specified for operation up to only 85 deg C so that plus the increasing noise of CMOS with elivated temperature probably makes it worth while to have a heat sink on it. The actual AD specification is for a T-junction max of 115 deg C which they say translates to a T-ambient of 85 deg C. We expecte a power dissipation in the AD9083 of between 1.0 and 1.4 Watts. For the AD9083's BC-100-8 package, AD specifies: Thermal Resistance Junction to Ambient 23.4 deg C per Watt Thermal Resistance Junction to Case Top 10.3 Thermal Resistance Junction to Board 8.9 Thermal Characterization Junction to Board 9.0 Thermal Characterization Junction to Case Top 1.2 I believe that the last value is used to estimate the junction temperature from the top of the case temperature when the top of the case is just in a still air condition, i.e. no heat sink on the top of the case. In our setup (which should be typical for the AD9083) we have a total of 42 BGA Vias tied to planes in the pcb: 20 for Gnd 8 for 1V0 Analog, 7 for 1V0 Digital, 5 for 1V8 Analog, and 2 for 1V8 Digital. This copper connection to the pcb planes is currently the main way for heat to flow out of the AD9083. We should be able to get about equal Thermal Resistance between the Board (i.e. pcb planes) to Junction and Case Top to Junction. Thus a heat sink on the top of the case can be effective in controlling junction temperature. Even with a 1.4 Watt dissipation we should be able to hold the Junction at about 10 deg C above ambient. The issue is how to make a good thermal connection bewteen the top of the AD9083 case and the Analog Section Shield Cover. ----------------------------------------------------------------- DATE: 7,10-Apr-2025 Topic(s): Review the components needed to finish the assembly of SN #0: - TI (Power Trends) DCDC Converters: 3 Amp: Qty Required 4 TI Part # PTH04T260WAD The PTH04T260WAD is not in stock at any of the normal distributors so I'm getting PTH04T260WAS to make certain that I have parts for SN #0. 6 Amp: Qty Required 2 TI Part # PTH04T230WAD - DPDT Center Off Switch for the +- 48V Power Supplies Carling 2GM54-73 - At least one dual SFP Cage (already have) AMP 2007263-1 - Platten for installing the dual SFP Cage - need to make Review the parts needed for MSU Final Assembly of the 38 production DK boards: - Dual SFP Cage: AMP 2007263-1 - M2.5 hardware (machine screw, flat washer, hex nut) for mounting the 3M J1 Main Cable and J7 Barnacle connectors require blue self locking machine screw: 95911A611 M2.5 x 16 mm machine screw with nylon patch 92005A074 M2.5 x 14 mm machine screw steel with zinc plating 93475A196 M2.5 flat washer standard 6.0 mm OD which fits the 5.0 mm screw head OD, and fits the DK's 7.0 mm OD Pads (oversize is 8.0 mm OD) 0.4 to 0.6 mm tall 93935A310 M2.5 SS standard Hex Nut 2.0 mm tall 93625A103 M2.5 SS Nylon Insert Hex Nut 3.8 mm tall Estimate the required length of the M2.5 machine screws for the 3M Connectors: The PCB is about 2.2 mm thick The 3M Connector is about 6.6 mm thick to the nut surface PCB + Connector + Washer + Std Nut = 11.3 mm PCB + Connector + Washer + Lock Nut = 13.1 mm - Nylon hardware (machine screw, flat washer, and hex nut) for the "hot" mounting hole in the J1 Main Cable connector: 94735A712 2-56 1/2" Machine Screw Nylon Black 94812A100 2-56 Hex Nut Nylon Black 90295A325 No 2 Washer Nylon Black - M2 hardware (machine screw, flat washer, hex nut) for mounting the Harwin J2, J3 PMT Signal connectors and for the Shield Cover mounting screws - require blue self locking machine screw or nylon insert hex nut: 93625A101 M2 Hex Nut with Nylon Insert 2.8 mm tall 91828A111 M2 Hex Nut 18-8 SS 1.6 mm tall 93475A195 M2 Flat Washer 2.2 mm ID, 5.0 mm OD, 0.2 to 0.4 mm thick 18-8 SS 91120A311 M2 External Tooth Lock Washer 2.2 mm ID, 4.5 mm OD, 0.2 to 0.4 mm thick 18-8 SS Estimate the required length of the M2 machine screws for the Harwin Connectors: The PCB is about 2.2 mm thick The threaded boss on the Harwin Connector is about 5.0 mm thick The full height of the Harwin Connector is about 5.9 mm thick The mounted height of the Transformers is about 6.0 mm Comfortable distance PCB top surface to Shield bottom surface is about 7.0 mm Full height of the Harwin plus 1.6 mm for plain hex nut plus min space 7.5 mm Shield is about 0.5 to 1.0 mm thick PCB + Flat Washer + Harwin Boss = 7.6 mm requires blue self locking screw PCB + Flat Washer + 7.5 mm + Shield + Lock Washer + plain hex nut = 12.9 mm self lock screw PCB + Flat Washer + 7.5 mm + Shield + Nylon Insert hex nut = 13.7 mm plain screw 95911A118 M2 x 8mm Machine Screw 18-8 SS with blue Nylon locking patch 92000A020 M2 x 14mm Machine Screw 18-8 SS Need to write a Check List for Hughes for on site checking of DK SN #0: - Component Orientation Plots: You get the best fill of the printed sheet if you plot from MG as Portrait and then convert to pdf with an orientation of "0". For the bottom side plots you can then mirror with: gs \ -o mirrored.pdf \ -sDEVICE=pdfwrite \ -c "<> setpagedevice" \ -f un_mirrored.pdf - DCDC Converter Part Numbers 3 Amp: TI Part # PTH04T260WAD Qty = 4 DCDC 1, 4, 5, 6 6 Amp: TI Part # PTH04T230WAD Qty = 2 DCDC 2, 3 -----------------------------------------------------------------