TEST FIXTURES

In-circuit test fixtures use a bed-of-nails interface to make direct electrical contact with individual nets on the populated PCB, verifying component presence, value, and orientation through parametric measurements. ICT catches manufacturing defects such as opens, shorts, wrong-value components, and missing parts. Functional test fixtures go further by powering the assembly, applying stimulus signals, and measuring system-level outputs to verify that the board performs its intended function under operating conditions. Calpak USA designs and builds both fixture types at our Hawthorne, California facility, and many production programs use ICT followed by functional test in sequence for maximum defect coverage. Our test engineers determine the optimal combination based on your board complexity, production volume, and fault coverage targets during the DFM and DFT review process.

Calpak USA requires Gerber files, the board bill of materials, schematic, and assembly drawings as the baseline data package for fixture design. A net list and board centroid file enable our test engineers to identify probe-accessible test points and plan bed-of-nails contact locations. For functional test fixtures, we also need the product specification document defining pass-fail criteria for each measured parameter, any available test procedures from your engineering team, and firmware or software images if the fixture will perform powered-up testing. If your design includes controlled impedance, RF sections, or high-current paths, flagging those areas early allows Calpak USA to select appropriate probe types and instrumentation. Our test engineering team at our Hawthorne, California facility reviews all documentation and provides a fixture design proposal with estimated coverage, fixture cost, and development timeline before fabrication begins.

Typical test fixture development at Calpak USA ranges from three to six weeks depending on complexity. A straightforward bed-of-nails ICT fixture for a standard-density board with fewer than 500 test points generally takes three to four weeks from design kickoff through fixture validation. Complex functional test stations requiring custom instrumentation, software development, pneumatic actuation, or multi-board test capability may take five to eight weeks. Calpak USA begins fixture design concurrently with PCB assembly setup during new program introduction, so the fixture is validated and ready by the time first articles come off the production line. Our Hawthorne, California test engineering team provides a detailed schedule with milestone dates during the design proposal phase. Expedited fixture development is available for programs with compressed timelines, typically adding premium costs for accelerated machining and overnight component procurement.

Yes. Calpak USA develops complete test software packages for functional test fixtures at our Hawthorne, California facility. Our test engineers write automated test sequences using LabVIEW, Python, and custom C or C-plus-plus applications that control instrumentation, apply stimulus signals, capture measurements, and evaluate pass-fail results against customer-defined acceptance criteria. Test software interfaces with bench instruments including digital multimeters, oscilloscopes, power supplies, electronic loads, signal generators, and communication bus analyzers through GPIB, USB, and Ethernet connections. Calpak USA builds operator-friendly graphical interfaces that guide technicians through the test sequence, display real-time results, and generate serialized test reports stored in our quality management system. Test programs are version-controlled and linked to specific board revisions, ensuring that engineering changes to the product are reflected in updated test coverage without disrupting production flow.

Calpak USA maintains all production test fixtures under documented maintenance and calibration schedules governed by our AS9100 Rev D quality management system. Probe pins, which wear over thousands of test cycles, are inspected on a defined interval and replaced before contact resistance degrades to the point of causing false failures. Pneumatic components, guide pins, and alignment hardware are inspected for wear during scheduled maintenance windows. Instrumentation connected to the fixture is calibrated per manufacturer specifications with certificates traceable to NIST standards. When your engineering team releases a board revision that changes test point locations, adds new circuits, or modifies acceptance criteria, Calpak USA updates the fixture hardware and test software under formal change control. Our Hawthorne, California facility retains fixture design files so that modifications and replacement fixture builds can be executed efficiently throughout the production program lifecycle.