Hybrids cables and clamps Tony Smith LHCb PRR
Hybrids, cables and clamps Tony Smith LHCb PRR - Tony Smith 1
Substrates CONSTRUCTION of composite SUBSTRATE • TPG central core 400 um • woven layer of CF prepreg each side oriented +-45 degrees 125 um nominal • woven layer of CF prepreg each side oriented 0, 90 degrees 125 um nominal • Carbon fibre frame 3 mm wide prevents delamination at the edges • Laminated between steel plates in a vacuum bag at Liverpool • Total thickness ~900 um LHCb PRR - Tony Smith 2
Substrates – 2 Profiling and drilling of SUBSTRATE • At Liverpool • Excess glue trimmed • Metrology and selection • At Stevenage Circuits • Profiling and corner jig holes drilled • Circuits laminated • PA, cooling and Assembly jig holes drilled LHCb PRR - Tony Smith 3
Circuits Four copper layers with Kapton dielectrics bonded with 35 um Espanex (modified polyimide) bondply – essentially a standard multilayer flexi circuit. DESIGN RULES - not very tight for the technology good yield 100 um track and gap 300 um vias - 500 um lands no buried vias Layer material pressed copper thickness 1 2/3 bottom solder resist 30 copper foil 05+carrier 5 um ------- SPB-050 A Bond Ply 50 um (was 35) -- -- SB 1250 Cop/Clad flexi 60 um 12 um 12/50/12 (Adhesiveless) 4 top (power) SPB-050 A Bond Ply 50 um (was 35) -- -- copper foil 05+carrier 5 um -- 5 um total 200 um (ground) NB – plating thickness of ~8 um Cu is added to top and bottom + Ni/Au on top LHCb PRR - Tony Smith 4
Circuit layout Layout showing top layer metal and inner layer traces Unusual build up. Top -Traces layer 2 - Vcc plane (split in 4) Layer 3 - inner traces Layer 4 – GND plane Circuits on both sides identical LHCb PRR - Tony Smith 5
Construction sequence Hybrid construction sequence Liverpool – TPG and CF Kits prepared TPG and CF kits laminated between steel plates in vacuum bag to form substrate Mark one side of hybrid with substrate number Stevenage Metrology and selection Substrate profiled, drilled and routed 2 Four layer kapton circuits produced, 2 per module Circuits electrically tested before and after Ni/Au process Circuits laminated to each side of substrate in vacuum press to produce hybrid Post lamination electrical test of hybrid Completed hybrids sent to Liverpool Hybrids selected and sent for hand population at Hawk Electronics LHCb PRR - Tony Smith 6
Hybrid Testing Electrical Test of populated hybrids • Test for shorts – most likely from soldering of connectors • Test for open circuits – most likely soldering – note – can only be partial • Test resistances of termination resistors and temperature sensor operation • Visual checks for component misalignment, solder splashes, damage, delamination etc. LHCb PRR - Tony Smith 7
Hybrid Twist • All hybrids have some degree of twist • Previous delays to schedule caused by attempting to understand control this • With more statistics it appears that there is still a significant spread • Twist changes after lamination at 180 degrees LHCb PRR - Tony Smith 8
Hybrid Twist LHCb PRR - Tony Smith 9
Hybrid Twist LHCb PRR - Tony Smith 10
Hybrid Twist • Twist during manufacture is difficult to control • We can live with it by: • Grouping the hybrids and machining paddles to suit • Heat treating between plates at 150 degrees • Expect yield to be 95% (90% including other cuts) LHCb PRR - Tony Smith 11
Hybrid Testing Shorts and opens test uses the cabtest B test board and a know good cable set. Set-up for Shorts and open circuit testing This uses LEDs to give quick visual identification of faults LHCb PRR - Tony Smith 12
Hybrid Testing Setup for resistance tests. The cabspy breakout board allows access to all the signal lines on te hybrid and a multimeter is used to check resistances. Nominal resistances and signal names are marked on the board to simplify testing The temperature meter shown below is used to verify the operation of the temperature sensors The resistance test LHCb PRR - Tony Smith 13
Cables are manufactured by Flexible technology Populated at Hawk Tested after population at Liverpool Setup for cable testing Cabtest. A and cabtest. B test boards are used to test the short kapton cables. LEDS are used to indicate continuity. Shorts are detected by energizing just one leg of each signal pair and will show up a fault if there is a short to adjacent pairs or to the power or ground planes. A good cable can be tested in less than a minute LHCb PRR - Tony Smith 14
Cables - Problems Cables are manufactured by Flexible technology They are designed to match the impedance of the long cables There are significant spreads in the resistance of the traces in prototypes (Short +/- 10% Long +/- 15%) Company promises to improve this with QA 16 sets of a 50 set batch promised today (28 Feb) We will see…. . LHCb PRR - Tony Smith 15
Clamps Cables are manufactured by Photofabrication Cable and clamp assembled and locked to the module base LHCb PRR - Tony Smith 16
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