HB RM prototypes Ianos Schmidt Aug 17, 2017

Overview Six sets (3 odd + 3 even) of HB prototype mechanics were produced at Iowa, five were carried to CERN. These HB prototypes are relatively crude Many missing features and shortcuts taken to expedite design and production in time for Testbeam RM’s however do have representations of most major components and features to maximize what can be learned from them Many small problems were identified during assembly All were correctable and was able to make the four RM’s for which we had components

Card packs and Card order HE RM HB RM Control card Control card HE and HB card-packs were made identical in card order and card spacing (allows testing of HB RM’s in HE backplanes) Note however that HB RM’s are wider

Card-pack Some issues, but card-packs went together with only a little difficulty once main problems corrected Missing pocket for QIE thermal pads on back side of plates. Pocket added to all plates taken to CERN Interference with large cap corrected Perpendicularity and flatness spec of top/bottom edges of cooling plates not met. Sacrifice to complete production on time. Unfortunately made assembly a bit more difficult, and impacts heat transfer

Card-pack cont. Pelt. transistor Control card transistor Fibers (and maybe JTAG cables) can be connected after card-pack assembly. Bend radius look reasonable Not sure where to put thermal pads on control cards. Pads placed to reasonably support board sandwich b/t cooling plates Same thickness thermal pads on top and bottom of boards Pelt. transistor Control card transistor

Mounting board and flex cables Mounting boards: Fit well in the thermal assembly Masking the areas that contact metal with Kapton tape was very tedious -> Protective coatings/masks/layers should be part of PCB manufacturing Flex cables (mounting board end): Connection to board was easy and does not appear to be stressed Flex cable stiffeners interfered with the assembly by ~0.7mm -> Required careful trimming and inspection, and insulation of edges from metal Trimmed un-trimmed Trimmed

Insufficient gap width to wrap around board Fingers too short to allow multiple bends without damage Fingers too short to allow multiple bends without damage Insufficient gap width to wrap around board

Flex cables!(card-pack end) Impossible to connect the shortest “finger” Second shortest connection almost impossible, was destroyed on RM#1 Connections very difficult to make, ~20 min/connection! Multiple twists and bends forced into a small area Insufficient gap width to reach other side of board Fingers too short to allow multiple bends without damage

Connected flex cables Despite difficulties, managed to connect most of them!

ODU In general ODU fit well into RM assembly, but is not without issues: Fiber bend radius much too tight for many fibers - Supporting fibers during gluing could help Will evaluate increasing angle b/t cookie and patch panel (now 90 degrees). Cookie skewed by force from fibers, does not want to line up well with SiPM packages - May need to introduce screws between cookie and cold assembly and/or change alignment scheme Fibers rub on some parts of the ODU/RM covers. Primarily at support for JTAG adapter board. - Expect to change adapter board and/or support piece. Not parallel Fibers rub at JTAG adapter board support Tight bend radius

Assembled RM (without covers)

Fit in RBX Backplane and RM’s fit into RBX. No conflicting features Features for clamping/extracting hardware were included in the prototype, however due to time constraints hardware components were not produced. Worries confirmed: - Spring fingers for pressing RM against RBX baseplate made insertion of RM’s into RBX very difficult Alignment with backplane connectors hard to achieve, risks damage to connectors. RBX does not have good provisions for aligning RM’s RBX’s are not exactly flat. May not have good thermal contact even with finger springs and clamping hardware. Look forward to seeing RM temperatures. would also like a measurement of DC-DC cooling plate temperatures Much more work needed! Location for RM clamp

Summary Six sets of mechanics produces although not ideal Problems discovered during assembly were corrected Four RM’s assembled Very useful in identifying where additional work is needed Particular concern is thermal contact with RBX and difficulty inserting RM’s Much more to be learned from these prototypes Much more work to do

Backup

Thermal assembly

HB RBX Megatile cables and source tubes go through RBX