Low mass tapes   for ATLAS SCT detector (Ljubljana ATLAS group)

Low mass tapes are flexible circuits  used to bring power and some control signals to the silicon module.  From the barrel  module - opto flex circuit to the patch panel (PP1) 50 microns thick Al is used as a conductor due to the requirement to have minimum scattering  in the SCT detector, while 35 micron copper is used as conductor forward modules. Aluminum  has 4 times better conductivity than copper at the same scattering length (see the material estimate ). Al tapes  with 100 microns thick Al were considered  in PP1 - PP2 region, however now thin  conventional cables  are a baseline.  Low mass tapes will supply  modules with necessary voltages for chip and detector operation, as well as with some control levels. It is foreseen to have one low mass tape per module.  Tapes  are  custom made by photolithography of aluminum  on the kapton substrate.  Al tapes were  made at ELGOLINE on 30 cm wide tape process and their design should allow large surface yield. 250 mm process was used for Cu tapes.

Specifications  of Al  LM cables

List of tape lengths  (barrel)

DATABASE   of low mass tapes

Electrical QA  results

Yield  of the production of barrel tapes

Yield  of the production of forward tapes

LM  links



Forward tapes and panels

Barrel tapes and panels

PP1B-V71     - version with holes for thermode solder rework


PP1B-V6Z is multilayer board (with 8 layers of conductors) accepting low mass tapes
from the barrel harness (6 tapes) and conventional cables from the power supply side.
It provides filtering of noise with same electrical layout as PP1V5.3. Top and bottom
layer (plane) conductors are connected to the shield.

Soldering of tapes and connecting cables  to the PP1B-V6Z
Schematic view of  one PP1B  or   two PP1Bs  mounted on cryostat wall
PCB layout of PP1B_V6ZA  (updated 21.11.2002) showing conductors in all layers
PCB schematic
Component placement  and FCI, JST pin definition
Dimensional picture of PP1B-V6Za  with its dimensions and positions of soldering pads  (updated 16.1.2003)
Connector    for conventional cable  - specifications
Low mass tape   layout
Patch panel EDMS document
Low mass tapes EDMS document

Alternative  designs  (a history)


SCT Barrel:

  •  low mass tape   layout
  •  PP1V5.3   electrical layout
  •  PP1V5.3     N and W  PCB design
  •  design of electrical layers  of PP1V5.3  N and W PCB
  •  Pin layout on Molex   240 pin connector
  •  pad layout  for soldering of tapes to PP1N
  •  cabling and soldering  of tapes to PP1N and interface PCB
  •  Molex 240 pin connector  data (PS file)
  •  harness lengths

  •   Voltage limiter:

  •   Irradiation  of limiters
  •  simulation  of limiter actions  at different limiter positions
  •  measurements  of limiter action with module
  • voltage limiter will be implemented on PP3-now development of Melbourne group
  • DESIGN for 2001 system test:

  •  cabling with module 0 harness
  •  barrel low mass tape design 2001   and forward low mass tape design 2001

  • New: next iteration of patch panels for 2001 system test (new mounting holes, changed filtering)
  • PP1N_V4 and PP1W_V4 schematic
  • PP1N_V4 and PP1W_V4 PCB layout
  • PP1N_V4 and PP1W_V4   pin layout
  • PP1N_V3 and PP1W_V3a  schematic (accepts low mass tapes on module side and conventional cable on PP2 side)
  • PP1W_V3a   PCB layout
  • PP0F   PCB layout and its schematic  for three modules with K4 hybrids
  • PP2 _V3 with voltage limiters  , connectors for conventional cables and its  time response
  • PP2_V3 with voltage limiters PCB for 6 modules
     DESIGN for the 2000 system test:

    May 1999 version of low mass tape was not in agreement with IPC -2223 standard which requires 2.5 mm spacing for 500V bias voltage.  Also few lines have been changed. Therefore  the  design 2000  of low mass cable for system test June 2000  is used.

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