Dev Fixture Guidelines

This guide provides best practices and component recommendations for building reliable Dev series test fixtures. These guidelines focus on optimal performance, assembly ease, and cost-effectiveness.

Guide Pins#

Spring guide pins are the preferred method for accurately locating the DUT within the fixture. For Dev series fixtures, use GP-2UL style guide pins.

For smaller locating holes (below 3mm), design custom cradles that mount to GP-2T or GP-2TL guide pins using M3 screws. The cradle captures the board edge or features when standard pin engagement isn't possible.

Pressure Pins#

All Dev fixtures should use 45mm pressure pins. Attach pins to the pressure plate with M3 x 10mm screws for secure retention during fixture cycling.

Position pressure pins over rigid board areas, avoiding components and flex regions. Distribute pins to provide even downward force across the DUT.

Receptacles and Probes#

Generic receptacles and probes are suggested as cost-effective options for development and prototyping applications. The lower cost supports short-lifecycle fixtures where probe longevity is less critical.

Recommended Configuration#

• Use "2" style collar (2.5mm collar height) for standard compatibility
• Adjust pressure pin lengths accordingly if using different collar heights

Probe Tips#

LM2 tips provide good general-purpose contact. A2 tips have geometry suited for making contact within populated through-hole connections.

Probe Plate Design#

The probe plate should include cutouts to prevent interference with tall components on the DUT. Review the DUT component placement and add relief pockets where components would otherwise contact the plate.

Design Process#

1. Import DUT STEP model or component height map
2. Identify components exceeding probe plate clearance
3. Add pockets or through-cuts for component relief
4. Verify adequate material remains around probe holes

Assembly Height#

Position the Device Under Test with its bottom surface 3.5mm above the probe plate. This height is optimized for:

• 45mm pressure pins
• 2.5mm collar height receptacles
• Standard probe travel

A mounting or tooling hole on the DUT ensures precise, repeatable alignment to this height specification.

Key Specifications Summary#

Differences from Dev Pro#

See Dev Pro Guidelines for Dev Pro specific recommendations.

Related Documentation#

• Fixture Bases — Dev fixture specifications
• Selecting Probes — Probe tip selection details
• DUT Locating — Board positioning methods
• Pressure Application — Pressure pin details