How To Quickly Detect Circuit Board Failure Problems？
Whether the electronic device is for personal use, commercial or industrial use, defects in the circuit boards inside it will cause adverse consequences. If you want to quickly detect which part of the circuit board is defective and cause the electronic equipment to not work properly, it will require work if you have a certain basic knowledge of electronics and skilled experience, and you must have a certain amount of patience. How to quickly detect circuit board failure problems?
1. Determine the fault location
As soon as there are signs of a problem with the board, we track and locate it until we pinpoint which defect is present on the board. Different ways to locate the fault include visual inspection, as well as physical inspection using test equipment. Test techniques rely on high-end test equipment or use basic tools such as multimeters, thermal cameras, magnifiers, and oscilloscopes.
2. Manual visual inspection and physical inspection
We can first check the appearance of the circuit board to see if there are any abnormal components, such as cracking, burning black, swelling and other abnormal appearances. There are also signs of overlapping traces, shorted solder joints, and overheating of the circuit board components on the circuit board. These are all defects that can be identified by visual inspection. There are also some problems that are difficult to identify with the naked eye, so we need to use a magnifying glass, which can help identify some problems such as short circuits, solder bridges, opens, cracks in solder joints and circuit board traces, and component offset.
3. Testing equipment
In addition to manual visual inspection and physical inspection, some defects require inspection equipment to detect specific circuit board failures. So what does the testing equipment include: ICT, automatic optical inspection (AOI) machines, burn-in test racks, functional testing, etc. AOI uses a high-resolution camera to check for a variety of defects, including shorts, opens, missing, correct or misaligned components, and the effect is very intuitive, letting you know exactly where the problem is on the board right away.
4. Specially detect components
When a low resistance is detected between component pins, the best way is to remove the component from the PCB circuit and conduct a dedicated test. If the resistance is still low, then this component is the culprit, otherwise further investigation is required.
5. Power up the circuit board for testing
Visual inspection is only suitable for visual inspection of circuit boards, not for internal layer inspections of circuit boards. If there are no visible defects on the outside, you will need to power up the board and perform a more detailed test to detect if the board is normal.
6. Low voltage measurement
The technique involves controlling the amount of current passing through the short circuit and finding out where the current is going. Since the copper traces on the circuit board also have resistance, the voltages developed through different parts of the copper traces are also different. With a voltmeter, as you measure the voltage between the different parts along the shorted line, the smaller the voltage, the closer you are to the short.
7. Use your finger to sense the heating area of the circuit board
Since short circuits can cause localized temperature rises on the board, finding areas with heat can help find where short circuits are problematic. However, be careful when using power supplies that short copper traces and avoid burns or electric shocks.
8. Fix short/open lines
After a short or open point has been identified on the board, the next step is to isolate the problem. While this is easy to do on the outer surface of the board, it is a challenge for the inner layers. Possible solutions include drilling through holes or cutting appropriate external copper traces.
As a professional electronic manufacturing service company, TECOO has professional testing equipment. For each product, we will conduct 100% functional testing according to customer requirements. If the customer does not have it, we will strongly request it. If the required files are still not available, our engineers will make a simplified test fixture based on the product's performance and schematics. After passing the test, each product is labelled.
