When partnering with an electronics manufacturing services (EMS) provider, you should feel confident that they have as much at stake with your product as you do. One way to determine this is to consider which testing methods the EMS provider employs.
Keep in mind, testing is completely different than inspections. Inspections are a routine requirement where a basic and preliminary review is done of products to confirm parts are correctly fitted, soldered, and in the right place. It does NOT, however, ensure your product works.
If your EMS provider is truly offering a full-service solution, they will have solid test solutions established to safeguard the products produced will work as designed.
ACDi has a full scope of testing capabilities to check every stage of products, from printed circuit boards just assembled to board level ICT and functional test, as well as assembled product functional tests and environmental stress screening.
ACDi’s electronics testing capabilities include:
- Bed of Nails/Flying Probe In-circuit testing (ICT)
- Systems Functional Testing
- Test Engineering Resources
- Functional Testing
- Environmental Testing
- Leak/Immersion Testing
- Custom Test Development
- Process Engineering Support
- Hi-Pot Testing
- Boundary Scan
- Various in circuit programming technologies
- Programming discrete memory, microcontrollers, etc.
Learn more about a few of the most popular tests we provide so you can rest assured we are taking every precaution to guarantee the success of your final deliverable.
During assembly, all boards are inspected using AOI and XRAY as appropriate.
After AOI and XRAY, ACDi provides two options for in-circuit testing to test the boards: flying probe and bed of nails.
ACDi’s flying probe development platform is the SPEA4060, chosen for its high rate of repeatability and precision. It can accurately and reliably strike 4 mil targets. The flying probe testing does not require special fixturing, which means it can be available and modified much faster than bed of nails testing. Most tests are generated as analog unpowered that provide test coverage for the following areas:
- Shorts– vectors determined via SPEA algorithm for most likely areas to demonstrate this type of defect to cut down on run-time.
- Opens– same as Shorts.
- Passives– with respect to this being in-circuit so this will give a nodal signature on each net and will provide not only an exhaustive ICT test, but assist in diagnostics should a unit become defective.
- Semiconductors – diodes checked for voltage drops as well as multiple vectors for BJT/Mosfets including Drain-Source resistance (Rds).
- ICs– depending on the library/model this will test each low-level IC for its intended function like measuring operational amplifiers.
- J-Scan– these are BGA and complex IC tests which measure the voltage drop across the ESD protection diodes inside the part. This will verify, for each pin it applies to, that the ball/pin is connected and the diode is working properly.
- E-Scan– this is a BGA test that involves placing an antenna probe on to the top of the BGA and injecting an RF signal, typically 100 MHz, into a pin on the net and attempting to detect the signal that is radiating from the die of the IC. This is highly effective at finding unsoldered balls.
Bed of Nails
A traditional electronic test fixture which allows electrical contact to be made simultaneously to every component on the board. It has numerous pins inserted into holes, which are aligned using tooling pins to contact test points on a printed circuit board and are also connected to a measuring unit by wires. We have two in-house bed-of-nails ICT testers to supports all program ICT needs.
ICs are either pre-programmed prior to assembly onto the board or programmed after installation with customer supplied files. If the ICs are not pre-programmed, they are typically programmed after ICT testing.
Boundary scan provides additional testing, which can provide testing of the following if accessible:
- Infrastucture– basic test from the test access port to all devices in the chain to verify connectivity and health of the signals.
- Interconnect– test vectors between boundary scan devices.
- Buswire– the complement to the interconnect test by testing drive capable boundary scan pins on bus type nets.
- Pullup/Pulldown– test the pullup or pulldown resistors attached to boundary scan pins that have them. It will attempt to toggle the state of the pins.
- Memory Testing– memory clusters can be checked from the Jtag chain but this may be omitted or truncated because of redundancy with respect to the functional testing.
PCBA Functional Test
ACDi can functionally test many types of printed circuit boards. The test procedure used may be a customer-supplied procedure or software, or created by ACDi. If ACDi creates the functional test procedure, we collect any available information including schematics, theories of operations, and more to generate the test procedure, then submit to the customer for approval.
PCBA functional tests may require test fixture and cable development, which ACDi can design and manufacture.
Tests may be very basic or complex (note: flying probe catches many manufacturing errors and functional testing may be able to be tailored taking this into account). The types of tests may include:
- Basic voltage and current checks
- I/O functionality checks
- Clock performance tests
- RF performance checks (full capability depending on product requirements)
- Product specific functionality
Full Product Functional Testing
Once the product has been fully assembled, similar functional tests can be performed at the product level. These tests are usually shorter than the combined total of all PWBAs as they are primarily testing that all connections were properly made.
Cable testing is based on cable complexity
- Basic lo- count cables are continuity tested for shorts, opens, and proper connections.
- More complex cables can be tested with our Cirrus 1100R+ cable tester.
Design Verification Testing
ACDi can assist in providing design verification testing (DVT). We can either execute a customer supplied plan or assist in developing a DVT plan. We can also manage third-party environmental or regulatory testing.
Environmental Stress Screening (ESS) Testing
We can provide various forms of ESS testing including temperature cycling and burn-in testing.
In addition to these common tests, ACDi provides in-house test engineers who run a cadre of tests for every product we produce, ensuring your product works as it was supposed to throughout every step of production. We have the flexibility to test at any stage of the production process, providing DFT services during design and final testing post-production. We provide this service to detect and diagnose manufacturing, component and design defects early on in the process, to maintain cost-effective measures, to promote efficiency, and because we are as invested in the success of your product as you are.