TPCB Design Guidelines#
These guidelines apply to customers designing their own TPCBs (Test Probe Circuit Boards) for use with FixturFab fixtures. If you prefer FixturFab to handle TPCB design, see the Auto TPCB option in Signal Interfaces.
Overview#
A TPCB routes signals from probe receptacles to organized connectors, replacing point-to-point wiring. Benefits include:
- Reduced assembly time: No hand-wiring labor
- Improved reliability: Fewer solder joints and connection points
- Easier replication: Identical signal routing across fixtures
- Cleaner integration: Standard connectors simplify instrumentation connection
Consigned TPCBs give you full control over signal routing while FixturFab handles fixture mechanical construction.
Mechanical Interface Requirements#
Your TPCB must interface correctly with the fixture's mechanical structure. These requirements ensure proper fit and alignment.
Board Outline
[PLACEHOLDER: Dimensional requirements including:
- Board dimensions by fixture size
- Corner radius or chamfer requirements
- Thickness requirements
- Keep-out zones]
Mounting Features
[PLACEHOLDER: Mounting hole specifications including:
- Hole positions
- Hole diameters
- Hardware clearance requirements]
Receptacle Pad Pattern
[PLACEHOLDER: Pad specifications for probe receptacles including:
- Pad size requirements
- Pad-to-pad spacing constraints
- Solder mask requirements
- Surface finish recommendations]
Signal Routing Guidelines#
Layer Stack Recommendations
[PLACEHOLDER: Recommended layer stack for different signal requirements:
- Minimum layer count
- Ground plane recommendations
- Power distribution considerations]
Trace Width and Spacing
[PLACEHOLDER: Guidance on:
- Minimum trace width by current
- Spacing requirements for voltage isolation
- High-speed signal considerations if applicable]
EMI Considerations
[PLACEHOLDER: Guidelines for:
- Ground plane coverage
- Shield signal routing
- Connector placement for noise immunity]
Connector Selection and Placement#
Recommended Connectors
[PLACEHOLDER: List of recommended connector types with part numbers and suppliers:
- High-density signal connectors
- Power connectors
- Programming/debug connectors]
Placement Guidelines
[PLACEHOLDER: Rules for connector placement including:
- Edge clearance requirements
- Orientation conventions
- Mating clearance considerations]
Design File Requirements#
When submitting your TPCB design to FixturFab, include:
Required files:
- Gerber files (all layers, drill files, outline)
- Assembly drawing showing connector positions and polarity
- Bill of materials (BOM)
Recommended files:
- Native CAD files (KiCad, Altium, etc.)
- 3D model (STEP format)
Design Review#
FixturFab reviews consigned TPCB designs before fixture production to verify mechanical compatibility. The review checks:
- Board outline and mounting features
- Receptacle pad positions match probe plate
- No interference with fixture mechanical features
We'll notify you if issues are found before proceeding with fixture production.
Common Design Mistakes#
Incorrect board outline: Board dimensions must match fixture specifications exactly. Verify dimensions against provided templates.
Missing mounting holes: Omitting mounting features prevents proper TPCB installation.
Pad misalignment: Receptacle pads must align with probe positions. Use the probe position file provided during fixture configuration.
Insufficient clearance: Components near board edges may interfere with fixture structure. Observe keep-out zones.
Wrong connector footprints: Verify connector footprints against actual components. Pin 1 orientation must match your instrumentation expectations.
Templates and Reference Designs#
[PLACEHOLDER: Links to downloadable templates:
- Board outline templates by fixture size
- Receptacle pad library
- Reference TPCB designs]
Getting Help#
If you have questions during TPCB design:
- Review the Auto TPCB option if design complexity is a concern
- Contact us with specific questions about mechanical interface
- Request a design review before ordering PCB fabrication
Submitting Your Design#
Include TPCB design files when placing your fixture order through Studio, or email designs to [PLACEHOLDER: email address] for review before ordering.