In-Circuit Testing (ICT)
Check accessible components and interconnections against a validated electrical program. Define test access, fixture scope, coverage limits and diagnostic records before production.
Find assembly faults at component and network level.
In-circuit testing evaluates selected electrical characteristics of a populated circuit board through accessible nodes. Depending on the system and program, it can assess interconnections, passive values and supported device behavior. Access, surrounding circuitry and the test method affect what is actually covered. [S27]
For a GlobalWellPCB assembly, begin with a coverage review rather than a target percentage. Identify the available test nodes, components requiring isolation or guarding, and requirements that will need another inspection or functional-test step.
Agree the electrical coverage and the access.
Send your board files, test-access details and required coverage to confirm the program and fixture needed for in-circuit testing.
Scroll the table horizontally to see all columns.
| Review area | What to evaluate | What to agree |
|---|---|---|
| Opens and shorts | Selected interconnection checks using the available test nodes. [S35] | Define what node access and isolation the intended program requires. |
| Passive components | Supported resistance, capacitance or related component checks in circuit. [S35] | Review parallel paths, tolerances and device-specific measurement conditions. |
| Semiconductor checks | Supported diode or other device tests, including additional powered/digital tests where applicable. [S35] | Specify safe test states and the actual device-level coverage. |
| Fixture access | Probe lands, spacing, board support and top/bottom contact needs. | Agree fixture design, mechanical protection and revision control. |
| Boundary scan | Compatible devices and a valid chain may support additional interconnect checks. [S29] | Confirm design support and test data; do not assume every board has usable JTAG access. |
| Complementary methods | Flying-probe assembly testing or FCT may address different production needs. [S28] | Compare access, development effort, cycle time and untested requirements. |
Tell us which features need inspection, your sampling requirements and the reports you need. We will confirm these details in your quotation.
From a clear requirement to a documented decision.
- 01
Review design for test
Provide the schematic, netlist, BOM and access data. Map required checks to reachable nodes and identify coverage gaps before fixture design.
- 02
Approve fixture and program scope
Agree mechanical support, power conditions, software baseline, ownership and validation criteria. Keep fixture development separate from production unit pricing.
- 03
Validate the test sequence
Confirm measurements and limits with controlled samples and appropriate known-condition checks. Investigate false failures and omitted tests before release.
- 04
Run and retain diagnostic history
Link results to unit identity and configuration. Record original failures, authorized repair and retest, along with fixture/program versions.
A coverage matrix is more useful than an unsupported percentage.
Ask for the agreed mapping from a component, net or requirement to its test. Coverage claims should define their denominator and explain inaccessible or excluded items.
- Coverage definition
- Tested components/nets, method assigned to each, exclusions and complementary checks.
- Configuration
- Board/BOM revision, fixture identity, program version and relevant setup checks.
- Electrical results
- Test identifier, applicable limits, measured value where agreed and the unit disposition.
- Diagnostic history
- Failing node/component references, repair authorization, retest outcome and final status.
ICT is not a complete operating simulation.
Passing selected component and interconnection checks does not prove every interface, operating mode or software function. Some ICT programs include powered tests, but that does not automatically make them a full functional-test sequence. Specify FCT requirements separately. [S35] [S31]
In-Circuit Testing (ICT) FAQs
Find answers about inspection methods, reports and approvals before placing your order.
Is all ICT performed with the board unpowered?
No. Many checks are unpowered, while suitable systems and programs may include powered or digital testing. Define the actual sequence and safe operating conditions instead of assuming one universal mode. [S35]
Is fixture-based ICT always preferable to flying probe?
No. Fixture cost, access, repeat volume, test complexity and production cycle time affect the choice. Compare the project economics and achievable coverage for the actual board. [S28]
Can every resistor and capacitor be measured accurately in circuit?
Not necessarily. Surrounding paths and access can limit direct measurement. Review guarding, isolation, alternative methods and excluded components in the coverage matrix. [S35]
Does a programming connector guarantee boundary-scan coverage?
No. The devices, chain, board connectivity and supplied test information must support the intended method. A connector labeled JTAG alone is not a coverage guarantee. [S29]
What happens when a board revision changes?
Assess test-point locations, component values, topology, limits and mechanical support. Update and revalidate the program or fixture as needed before using it for the new revision.
Should failed boards simply be tested repeatedly?
No. Define contact-check and retest rules. Preserve original failures and confirm authorized corrective action so a later pass does not erase an unresolved issue.
Technical references
- [S27]Teradyne — TestStation Systems: In-Circuit & Functional Production Test Platform (PDF)
- [S28]SMTC — Flying Probe Test
- [S29]Keysight — Requirement for Successful Boundary Scan Test Development on i1000D In-Circuit Test System (PDF)
- [S31]NI — PCB Assembly Test Toolkit overview
- [S35]Teradyne — TestStation Systems: In-Circuit & Functional Production Test Platform (PDF)
Explore the inspection and testing references below. Include the applicable standards, acceptance criteria and required records with your enquiry so we can confirm the inspection plan for your board.