Functional Testing and Its Costs
Functional testing (FCT) can determine whether a PCB assembly is functioning well before delivery.
Is functional testing necessary for PCB assembly?
If your PCB assembler does not perform functional testing your boards, when you get them and something goes wrong, your device has to be returned to the PCB assembler for inspection and troubleshooting. However, this is a difficult process because AOI testing can only detect surface defects in the assembly, and in this case, even a dedicated assembly team has difficulty detecting errors inside the PCB.
You and the manufacturer are frustrated because no one knows whether the problem lies with the assembler, the component, or the circuit designer. Things get complicated. It’s bad, and it’s even worse, it’s happening in the PCB industry. So yes, we think functional testing is required to ensure the highest quality.
What is PCB Assembly Functional Testing?
Functional testing (FCT) is performed after assembly and before thermal aging testing. It tests the functional performance of the PCBA by simulating the operating state.
Yingstar handles functional testing as follows:
First, our senior test engineers program the tests in LabView.
Then connect the PCB assembly to the PCBA tester, start the test program, and power up the PCBA. (Our test system is written in Visual Basic.)
Technicians then use a PCBA tester to receive the signals from the PCB die and route them to test points.
Thus, voltage values, signals and other relevant characteristics are fed into the oscilloscope in this way. The oscilloscope is connected to the computer, if the PCBA is OK, the screen will show OK, otherwise it will show NG (not good), so that our experts can evaluate the signal integrity and determine whether the voltage is working properly.
Capture all data from the testing process. If the computer says “OK”, the PCB assembly goes to the next step which is IC programming or thermal aging test. If the computer shows NG, our engineers will troubleshoot and restart all PCBA tests.
Usually, we recommend customers with PCB area more than 3 square meters to do functional testing. It shows any open connections, faulty components, solder shorts, and other issues with the PCB. It is used by PCBA manufacturers to ensure superior precision in assembly quality.
How much does functional testing for PCB assembly cost?
Generally speaking, if you ask the PCB assembler to perform functional testing before delivery, you have to pay extra. The cost of functional testing varies by PCB assembly company. Functional testing costs between $0.1 and $1 per PCB assembly.
YINGSTAR is a full-service PCB manufacturer offering free functional testing. We provide precision PCB, PCB assembly, electronic parts sourcing and functional testing services. We welcome large batches, small batches and prototypes.
YINGSTAR offers a variety of free tests and services, including one-on-one engineering assistance, Gerber and BOM inspections before production, and PCBA first article testing. Also for your first sample order, you can receive a $100 coupon.
Advantages of Performing FCT on Your PCB Assemblies
Functional testing has the following advantages:
- Functional testing saves consumers the expense of purchasing equipment to detect defects or paying testing houses, which are much more expensive.
- It eliminates the need for system testing.
- It contains most of the parts of the PCB such as resistors, voltages, communication protocols, and anything else that might cause problems with the PCB.
- This is also the stage where the manufacturer can add additional serialization elements such as serial numbers and calibration parameters.
During functional testing, the entire operating environment within the PCB is cleared of faults. You can check responses at designated points to confirm product performance and prevent failures. This is critical for regular customers who may not be able to resolve the issue themselves.
