How Functional Testing Works for PCB Assembly?

Printed circuit boards (PCBs) have become an integral part of electronic devices used today. These devices are driven by PCBs, and they form a thin layer base of how the circuit functions. This is why their structure and function, both are crucial aspects from the point of view of the performance of the final product. With the increasing demand for high-speed, performance-driven yet miniature devices, circuit board designs have become increasingly complex. While a PCB design should be flawless, its functioning in the required application environment is just as important. Hence, PCBs are subjected to a number of inspection techniques at each stage of production. Of all the testing techniques, functional testing comes at a later stage but is extremely crucial. In short, this technique tests the PCB functioning in a simulated environment. This tests the functioning of components, parametric values, and functionalities as per the requirement.

A Brief Introduction on Functional Testing

Functional testing is the final step of PCB manufacturing to ensure zero-defect PCBs. At this stage, the design is already tested for, and hence the functioning of the PCB is checked at length and at various levels. The application environment is simulated; PCBs are connected to similar systems and with the same final product. This technique is all about going as close as possible towards the real environment. This step gives the manufacturer a green signal to proceed with further processes. As the name implies, this technique verifies the functionality and behavior of the circuit boards to ensure their flawless performance. Functional testing is unique compared to other testing methods. For example, unlike in-circuit testing (ICT), where each component is examined after being soldered in the circuit board, functional testing is all about the overall functionality of the circuit boards. The following section describes the common problem identified through functional testing. It’s like giving a final clearance before the assembled PCB is shipped out.

Common Problems Identified Through Functional Testing

Here is the list of some common problems that can be identified by performing functional testing of PCBs. So, let’s have a look at them.

  • Power Integrity: This is one common problem in high-speed boards that run at fast edge rates. Some common power integrity issues are power rail collapse and ground bounce, excessive heat generation, and high AC impedance and/or DC resistance. The PCB functional test identifies factors that contribute to PDN resistance and impedance.
  • Inadequate Voltage/Current: In most cases, the circuit board fails or does not perform as expected due to inappropriate voltage or current supply. Sometimes, PCB components are subjected to more than normal voltage and subsequent overheating. In addition, the incorrect voltage could occur by placing components in the wrong places or missing them somewhere on the board. PCBA manufacturers analyze these problems via functional testing and take proactive steps accordingly.
  • Signal Distortion: Signal integrity issues in the circuit board can also affect its functionality. This signal distortion can occur due to various reasons such as crosstalk, impedance mismatch, and more. PCB functional test checks for excessive signal distortions, signal skew in buses, and other weird behavior in the circuit board that may affect its functionality.

Why is Functional Testing So Popular?

Functional testing is widely used by PCBA manufacturers and service providers owing to its following benefits.

  • A functional test detects any faulty or inappropriately placed components. It triggers root cause analysis for any type of fault in the circuit board.
  • Compared to other PCB test methods, functional testing is cost-effective and straightforward.
  • The individual can document the entire process. This, in turn, acts as a guideline for improving the overall quality.
  • This method tests the whole circuit board. So, there are zero chances of defects or errors.
  • Functional testing works in sync with other PCB testing methods, such as in-circuit and flying probe testing.
  • As mentioned, this testing allows the PCBA manufacturer take the final call and approval from the client as well.

Accuracy and precision are two crucial aspects of circuit board manufacturing and assembly. The application will perform effortlessly with high-quality circuit boards. Therefore, it is essential to check these aspects while manufacturing and assembling PCBs, and validate the same via testing and inspections. If you are an OEM looking for a PCB assembly services provider for your upcoming projects, you must consult Rigiflex Technology. Being one of the experienced and reputed industry players, Rigiflex Technology offers PCB manufacturing, assembly, and testing services for industries. This guarantees circuit boards are made using the finest quality components and will meet the application requirement of several challenging applications.