PCB Testing Methods
Testing PCBs during assembly is an integral part of our manufacturing process. As a reputable electronics contract manufacturer, we Fubon Precision offer a variety of PCB testing methods, to make sure all our boards are dependable and of high quality
Testing printed circuit boards (PCBs) is a crucial step in the manufacturing and quality control process to ensure that the boards function correctly and meet the required specifications. There are several methods for testing PCBs, depending on the stage of production and the level of detail required. Here are some common PCB testing methods:
Visual Inspection:
Visual inspection is the simplest form of PCB testing.
It involves examining the PCB for physical defects such as soldering issues, component placement errors, and damaged traces.
Technicians can use magnification tools like microscopes to perform detailed inspections.
Automated Optical Inspection (AOI):
AOI systems use cameras and software to automatically inspect PCBs for defects.
These systems can detect issues such as missing components, wrong polarity, soldering defects, and more.
AOI methods of testing typically use a single 2-D camera or two cameras for a 3-D photo of the PCB. A computer program compares the photos of the board to a detailed reference photo. If the photo does not match the reference photo to a certain degree, the program flags the board for inspection by a technician.
AOI methods are useful for detecting issues early in the manufacturing stage. We use AOI methods at various stages of manufacturing—after solder paste deposition, after component placement, and after reflow soldering. However, as the test does not require powering up the board, it is not a completely foolproof method.
But AOI is faster and more accurate than manual visual inspection.
In-Circuit Testing (ICT):
ICT is a comprehensive method that tests individual components and connections on the PCB.
It involves the use of a specialized fixture to make electrical connections and measure component values.
ICT can identify issues like open circuits, short circuits, and component value deviations.
Flying Probe Testing:
Flying probe testing is an alternative to ICT, primarily used for low-volume or prototype PCBs.
Instead of a fixture, this method uses robotic probes that move around the PCB to make electrical contact and perform tests.
Flying probe testing is more flexible and cost-effective for small production runs.
Boundary Scan Testing (JTAG):
Boundary scan is a standardized method for testing digital components on a PCB.
It uses a dedicated Test Access Port (TAP) controller and boundary scan cells to test and diagnose digital ICs.
Boundary scan is useful for detecting issues related to digital signal integrity and connectivity.
Functional Testing:
Functional testing verifies that the PCB functions correctly in its intended application.
It involves applying power to the PCB and testing its inputs and outputs while simulating real-world conditions.
Functional testing is used to ensure the overall functionality and performance of the PCB.
Environmental Testing:
Environmental testing involves subjecting the PCB to various environmental conditions, such as temperature extremes, humidity, and vibration.
This helps ensure that the PCB can operate reliably in different environments.
X-ray Inspection:
X-ray inspection is used to examine the internal structure of PCBs, especially for hidden defects like solder joints beneath components.
X-ray testing is necessary for inspecting parts of the PCB that may not be visible under normal conditions. This includes soldering under BGA and similar ICs and internal PCB layers. BGA and similar ICs hide solder joints underneath the chip package. However, X-ray inspection methods require trained and experienced operators. Also, not all the PCB can be examined or inspected using X-ray methods, but it is possible to view:
—Hidden Solder Joints
—Traces on Internal Layers
—Barrels of Plated-Through-Holes
—AXI tests can be 2-D or 3-D, with the latter offering faster testing.
While we restrict the above two testing methods primarily to assembly processes, we use other testing methods after completing the PCB assembly.
Thermal Imaging:
Thermal imaging is used to identify hotspots or abnormal temperature variations on the PCB, which can indicate potential problems.
Burn-In Testing:
Burn-in testing involves subjecting the PCB to extended operation under stress conditions to identify potential early failures.
The choice of PCB testing method depends on factors like the volume of production, the complexity of the PCB, and the specific requirements of the project. Typically, a combination of these testing methods is used at different stages of the manufacturing process to ensure the highest quality and reliability of the PCB.
At Fubon Precision, we are committed to providing our customers with the highest quality PCBs that are designed to meet their specific needs and requirements. We use state-of-the-art manufacturing techniques and train a team of experienced professionals. Committed to ensuring the highest level of quality and reliability in PCBs, providing our customers with the best possible product foundation.
We take great pride in our work and are confident that our PCBs will exceed your expectations. Contact us today to learn more about our services and how we can help you with your next PCB project.