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Functional Test Fixtures and In-Circuit Testing for Industry

In-Circuit TestingWhile there are many different types of testing available for the manufacturing industry that is designed to meet the demands of advances made in technology and different kinds of devices, functional and in-circuit testing are two popular options available for effective testing strategies. In-circuit test fixtures (ICT) and functional test fixtures (FCT) are what we will be discussing in this article. As the manufacturing process improves and changes are made in the way that interface test adapters and components are used, the options for testing will continue to evolve. While a majority of the focus used to be on In-Circuit testing as the preferred method, today more attention is now given to functional test fixtures for things like printed circuit board (PCB) assemblies.

In-Circuit Test Fixture

In order to make an informed decision, it is important to know a little bit about each type of product. An in-circuit test fixture tests individual components of a printed circuit board one at a time. It compares the results against a software model of the parameters for the component. This is known as a “schematic verification,” due to the way that the testing is performed. It is very effective at uncovering any defects in the manufacturing, in spite of the fact that it does not test “at speed” and cannot verify interoperability.

In-Circuit Testing is excellent for locating manufacturing defects, such as open connections, wrong or missing components, and solder shorts. It can also perform tests without power being applied to the device under testing to avoid causing damage to the assembly. Unfortunately, an in-circuit test fixture cannot test continuity through connectors. As a result, any faults in the connectors won’t be identified by using this type of testing for a printed circuit board assembly.

In-Circuit Testing and Functional Test Fixtures

Unlike the in-circuit test fixture, functional test fixtures are able to verify that a printed circuit board is functioning properly by applying a stimulus to an assembly and then verifying the response. The primary goal of functional test fixtures is to ensure that the functions of the circuitry are within the manufacturer’s specifications. This type of testing is done “at speed” through the use of device under test (DUT) connectors. Some of the major benefits of functional test fixtures include having the ability to identify functional defects in a printed circuit board and assess that functionality while only having to apply a marginal amount of voltage or current to protect the assembly.

EMC Technologies has extensive experience working with interface test adapters (ITA). Advantages include the use of a custom backplane printed circuit board for power and ground connections, a custom utility board PCB for additional loads and relays, removable access panels, or a redundant interface to provide multiple connections to a single point.

Other benefits associated with using functional test fixtures instead of an in-circuit test fixture include having the ability to determine DUT power consumption during the operation and uncovering problems with the analog circuitry, including drive currents of power output circuits, analog signal clipping or distortion, bandwidth issues, amplifier gains, issues with the oscillator frequency, and adjustment issues with the potentiometer. Functional test fixtures can also help to reveal digital circuitry issues, including design or component related signal timing issues, and communications issues. High speed instrumentation is used to characterize signals from the DUT, which can be more costly than low speed measurements, however many of our clients demand high speed testing.

Contact EMC Technologies for Functional Test Fixtures

If you are interested in learning more about how custom solutions for functional test fixtures can benefit your business, contact our team of engineers and technicians by calling 508-672-0808. We design and manufacture discretely wired and wireless functional test fixtures that are used by our clients to verify the performance of printed circuit board and electronic assemblies. We have also created many different commercial applications across many different industries including computer servers, networking, telecommunications, medical, satellite TV/IP, military and military contractors. Our experience in the development of customized interface test adapters for the support of aerospace and military programs gives us a big advantage over other services, due to the demanding and challenging products that we have been contracted to produce. Call today for a FREE QUOTE on any of our services or to learn more about the custom services that we provide.