Design for Testability — Pabst Electronics

Why Testability Must Be Designed In

Testability Determines Production Quality

In-circuit test (ICT) and functional verification test (FVT) are the most effective tools available for catching assembly defects and verifying product function before products reach customers. But their effectiveness — and their cost — is almost entirely determined by design decisions made during PCB layout.

A board designed without testability in mind may require expensive workarounds, may achieve only partial test coverage, and may necessitate costly layout revisions to achieve an acceptable test strategy. Incomplete test coverage means defective boards reaching customers. High fixture costs mean delayed production ramp. Poor test access means slow test cycle times and high cost-of-test.

Experienced engineering teams design testability in from the beginning — delivering PCB layouts with full or near-full test coverage in fewer layout iterations, with lower fixture costs and faster production line qualification. That is exactly what Pabst Electronics delivers on every project.

DFT Engineering Approach

1

Test Strategy DefinitionICT vs. FVT vs. boundary-scan — defined at architecture phase

2

Test Point PlanningEvery testable net receives a correctly sized and located test point

3

Bed-of-Nails Keepout ZonesFixture keepout zones defined and enforced in layout

4

JTAG / Boundary-ScanBoundary-scan access included where applicable for digital coverage

5

FVT Stimulus & MeasurementHardware connectors and test modes defined for functional testing

6

Test Coverage ReportNet coverage analysis before layout completion

Test Types We Support

ICT, FVT, Boundary-Scan & EOL Test Design

🔌 In-Circuit Test (ICT)

ICT verifies the correct placement and value of every component on the assembled board. Effective ICT requires a test point on every net and a bed-of-nails fixture with proper keepout zones. We design ICT access into every layout, maximizing coverage and minimizing fixture complexity.

⚡ Functional Verification Test (FVT)

FVT verifies that the assembled board functions correctly — not just that components are present and within value. We design FVT stimulus and measurement access into the hardware, define the FVT test modes in the firmware, and create the FVT specification in parallel with hardware development.

🔗 Boundary-Scan (JTAG)

For boards with JTAG-capable devices, boundary-scan provides structural test coverage without physical test probes. We implement JTAG chains, ensure proper TAP controller access, and can develop boundary-scan test programs to complement ICT and FVT strategies.

🏭 End-of-Line (EOL) Test

EOL testing is the final production quality gate before the product is packaged and shipped. We design EOL test procedures that are fast, reliable, and fully automated — verifying the complete product function including mechanical assemblies, enclosure interfaces, and labels.

📊 Test Coverage Analysis

Before the PCB layout is finalized, we perform a test coverage analysis to identify any nets that cannot be reached by the planned test strategy and to determine whether additional test points or design modifications are needed to achieve target coverage.

🔧 Fixture Coordination

We coordinate with ICT fixture vendors to ensure that the test point placement, keepout zones, and board geometry are compatible with standard fixture fabrication processes — reducing fixture cost and lead time.

Want Full Test Coverage Without the Fixture Rework?

Design testability in from the start and avoid the costly layout revisions, partial coverage, and slow cycle times that come from adding test access as an afterthought.

Talk to a DFT Engineer