Printed Circuit Board Manufacturing

1
GlueX Electronics Review Jefferson Lab July
23-24, 2003 R. Chris Cuevas Jefferson
Lab Physics Division Group Leader -- Fast
Electronics
Topics Printed Circuit Board
Manufacturing Maintenance Power
Grounding
2
PCB Manufacturing

• JLAB Electronics Group GlueX collaborators
  have extensive experience with design and
  ordering PCBs in industry.
• PCB is not a mechanical part!
• Electrical characteristics more important than
  mechanical tolerances
• Design Tools are essential for verification
• We have PCAD, Gerber View Tools but,,,
• More extensive simulation tools would be useful
• (e.g.) PCB layout simulation, signal integrity
  modeling

3
PCB Manufacturing

• 1000s of custom PCBs have been manufactured in
  industry for CLAS. Drift Chamber, Level II
  Trigger, Timing distribution
• Typical PCB development procedure
• Design requirements -- Specifications/Format
• EECAD -- Schematic capture -- Board layout
• Prototype ordered -- Assembled on site
• TEST -- Verify circuit performance -- Record
  results
• Capture all ECOs Engineering Change Order

4
PCB Manufacturing

• Procedure continued
• Verify all ECOs in new layout
• Prepare order for contract manufacturing
  assembly
• Evaluate manufacturers -- Not on price alone!
• Long term reputation/experience
• Documented Quality Control standards IPC,ISO
• Automated assembly equipment
• Bare board test equipment
• 1st Article assembly very important

5
Maintenance

• No glamour, but planning NOW is critical for high
  availability
• Must plan for spare PCBs for each custom design
• Crucial components must be identified
• Spare devices purchased for long term
  replacement
• DOCUMENTATION -- Must archive and provide
  on-line
• Schematics
• System/Wiring Diagrams
• Maintain Firmware Development Tools and Code
• Test Programs

6
Maintenance

• High Availability Demands
• Low Mean-Time-to-Repair
• Example Powered Card Enclosures Crate
• Removable power supply units
• Removable fan tray
• Easy access to circuit boards -- test points
• Remote monitoring of Crate systems -- V, I,
  Temperature
• Remote reset feature where applicable

7
Maintenance

• Planning for the repair shop
• Must provide training for technicians on new
  designs
• Test Stations for all custom and commercial
  boards
• Ability to repair/rework circuit cards, power
  supplies
• Assure proper tools and test equipment are
  provided
• Establish circuit board calibration/repair/track
  ing database
• Use new technologies for keeping track of all
  modules in the experiment. RF Id,, Bar code

8
Power Grounding

• Very extensive topic and,
• We have good experience with Hall B CLAS
• Careful planning of power isolation and grounding
  grid
• Extensive review of AC Mains requirements
• Must include grounding grid requirements for
  Accelerator connection and civil engineering
• Must identify all large consumers of AC Mains
• Superconducting Magnet system
• Building utilities HVAC, LCW, Pumps, Crane
• Front End Readout crates
• High Voltage systems

9
Power Grounding
10
Power Grounding

• Reasons for Grounding
• Shock and Safety Hazard Control
• Reduce lightning related gradients
• Avoid injury to personnel
• Avoid damage to Electrical/Electronic equipment
• Establish return reference
• EMI control
• Shield reference for cables, isolation
  transformers

11
Power Grounding

• Learn from omissions CLAS example
• Plan for dedicated network conduit(s)
• High speed network gear beam-line diagnostic
• equipment not in close proximity to detector
  power supplies
• Low radiation levels in Hall D
• Should allow extensive use of Fiber Optics for
• Communication links --
• Data acquisition --
• Optical isolation for control circuits where
  applicable

12
Summary

• PCB Manufacturing
• Excellent design record.
• Almost zero problems with production PCBs in CLAS
• New design/verification tools would be beneficial
• Maintenance
• Electronics Group is a small efficient group
• Large portion of readout electronics for CLAS and
  other Halls are mostly commercial aging
  electronics
• Custom electronics will demand better tracking,
  repair and long term availability of crucial
  components
• Power Grounding
• Careful review of AC Mains requirements NOW
• Requirements for detector power supplies, HV,
  Front End crates need to be established,,,
• Grounding/shielding configuration is crucial for
  low noise measurements and reducing EMI pickup