LAT Tracker Engineering 7 May 2004, 2004 TMCM Board Fit-Up on Tray Closeouts

1. LAT Tracker Engineering 7 May 2004, 2004 TMCM Board Fit-Up on Tray Closeouts Martin Nordby nordby@slac.stanford.edu Mike Foss mike@slac.stanford.edu

2. Top and Bottom Tray TMCM Board Fit-up Bottom Tray 3x 1.7 mm diam holes in closeout Holes match perfectly 2x 3 mm diam holes in closeout. Holes match perfectly TMCM Pin thread interferes with Flex Cable  modify Pin design so it is flush or do not use pin here No hole in Corner Bracket No hole in Corner Bracket 2x 1.7 mm diam holes in closeout, and hole clear Corner Bracket. Holes match perfectly TMCM Pin thread interferes with Flex Cable  modify Pin design so it is flush or do not use pin here 1.7 mm diam x 5 mm deep hole in Corner Bracket offset by 0.52 mm from hole in board (each end) Top Tray 5x 1.7 mm diam holes in closeout Holes match perfectly 1.7 mm diam hole in closeout offset by 1.19 mm from hole in board (this end only) 2x 2 mm diam holes in closeout. Holes line up perfectly. TMCM Pin thread interferes with Flex Cable  modify Pin design so it is flush or do not use pin here 2x 1.7 mm diam holes in closeout. Holes match perfectly. TMCM Pin thread interferes with Flex Cable  modify Pin design so it is flush or do not use pin here

3. Mid-Tray TMCM Board Fit-up Mid Trays 7x 1.7 mm diam holes in closeout Holes match perfectly 1.7 mm diam hole in closeout offset by 1.19 mm from hole in board (this end only) 2x 1.7 mm diam holes in closeout. Holes line up perfectly. TMCM Pin thread interferes with Flex Cable  modify Pin design so it is flush or do not use pin here 2x 2.1 mm diam holes in closeout. Holes match perfectly. TMCM Pin thread interferes with Flex Cable  modify Pin design so it is flush or do not use pin here Other Comments on the Pin Design All MCM Closeouts are 5 mm thick, and pins are 7 mm long, so pins extend into honeycomb core region. This could result in pin hitting honeycomb core edge-on during TMCM assembly  Proposed Solution: shorten pin to 4.5 +/- 0.1 mm to ensure it never extends beyond closeout and does not bottom out in Corner Bracket hole M1.6 thread on pin has 0.8 long undercut at base, to allow pin to slide on the TMCM Board. However, the board is thicker than this, so this can not meet the intended purpose  Proposed Solution: increase length of undercut to 1.22 +0.2 / -0 mm long from base of flange TMCM Board stayclear length is 359.6 mm, according to LAT-DS-00899-08. Width of recess in trays is: Mid-trays: 360.1 +/- 0.25 mm Top tray: 360.09 +0.2 /-0 mm Bottom tray: 360.0 +0.5 / -0.1 mm (this is set by Corner Brackets)  Proposed Solution: according to these widths, there is little room to align the TMCM Board on the tray with respect to the Bias Circuit. If this alignment is essential, then the Bias Circuit needs to be positioned with respect to the MCM Closeout recess, and not the 3 mm alignment holes

4. TMCM Pin Modification Proposal Proposed Changes to Pin Increase length of undercut diameter from 0.8 +/- 0.1 mm to 1.22 +0.2 / -0 mm Reduce diameter of pin from 1.2 to 1.0 +0/-0.1 mm Shorten pin from 7 to 4.5 +/- 0.1 mm long Keep M1.6 thread as-is but do not use around Flex Cable Proposed Map of Holes to Use Use pins in these locations with conductive Nusil for grounding the electrically connecting the Board to the Closeout and Corner Brackets Mount pins in these holes with standard epoxy Do not use this hole. Alternatively, make a pin with just a thread and flange, but no pin Do not use pins in these holes. Alternatively, make a truncated pin with no thread to produce the correct spacing between the TMCM Board and Closeout Do not use this hole. Alternatively, make a pin with just a thread and flange, but no pin

5. Pattern of the MID and Top trays TMCM pins 4 fixation pins glued with 3M2216 4 holes left without pin 3 grounding holes with pins glued with Nusil 2646 Pattern of the Bottom trays TMCM pins 2 fixation pins glued with 3M2216 6 holes left without pin 3 grounding holes with pins glued with Nusil 2646