DFT Report Guide

This guide explains how to interpret your Design for Test (DFT) report in FixturFab Studio. For step-by-step instructions on generating a report, see Creating a DFT Report.

Report Summary Overview#

The DFT Report Summary displays a preview and comprehensive summary of your Device Under Test (DUT) characteristics. The summary header shows the name of the DUT, date the report was created, and a status bar indicating whether there are errors or warnings.

Understanding Report Sections#

Device Under Test Features#

This section extracts information from your design file (ODB++ or IPC-D-356):

• DUT/PCB dimensions — Board width and depth measurements
• Double-sided probing — Whether probing is required on both sides
• Locating methods — How the DUT will be positioned in the fixture
• Test point counts — Total number and breakdown by type
• Minimum test point features — Smallest pad sizes and spacing detected

Net Information#

Displays your design's electrical connectivity metrics:

• Net quantity — Total number of nets in the design
• Probed net count — Number of nets with accessible test points
• Coverage percentage — Ratio of probed nets to total nets

Greater net coverage is better for comprehensive testing. However, functional test fixtures can evaluate non-accessed nets through proper test planning—measuring downstream effects rather than direct probe contact.

Probe Information#

The report recommends probe types based on center-to-center spacing requirements:

These counts are suggestions that may change during detailed fixture design based on mechanical constraints and probe availability.

Issue Summary#

An expandable tree displays all identified errors and warnings from the DFT analysis:

Errors — High-risk issues that could affect manufacturing feasibility:

• Insufficient probe spacing
• Inaccessible test points
• Mechanical conflicts with components

Warnings — Moderate-risk concerns that may affect fixture reliability or cost:

• Marginal spacing
• Test points near board edges
• High-density areas requiring special attention

Design Recommendations#

Optimal test point specifications for reliable probing:

Additional recommendations:

• Same-side probing preferred — Avoid double-sided probing approaches when possible
• Mounting holes — Include at least two holes at 1mm+ diameter for DUT locating
• Test point placement — Keep test points accessible and away from tall components

Common Questions#

What does "test coverage" mean?#

Test coverage represents the percentage of your design's nets that can be accessed through probe contact. Higher coverage means more comprehensive electrical testing is possible. 100% coverage isn't always necessary—focus coverage on critical signals and power rails.

My coverage is lower than expected. What can I do?#

Common causes of low coverage:

• Test points too close together (increase spacing to 2.54mm minimum)
• Test points obscured by tall components (relocate test points)
• Missing test points on critical nets (add dedicated test pads)
• Double-sided designs requiring probing from both sides (consider single-sided access)

How do I improve my DFT score?#

For future board revisions:

• Add dedicated test pads on critical nets
• Maintain minimum 2.54mm spacing between test points
• Keep test points 1.27mm away from component bodies
• Include mounting holes for DUT locating
• Consider test requirements during component placement

Using the Report#

Download Options#

Reports can be exported in PDF format for sharing with stakeholders or archiving with project documentation.

Sharing with Your Team#

Use the report to facilitate discussions between test engineers and PCB designers about testability trade-offs early in the design cycle.

Next Steps#

After reviewing your DFT report:

1. Address any errors that could affect fixture feasibility
2. Review warnings and decide which to address
3. Proceed to configure your fixture with your DFT insights

Need help interpreting your specific report? Contact us for guidance.