15 common PCB faults and solutions

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Regardless of whether it is an engineer or a PCB manufacturer, it is impossible to avoid PCB failures. The emergence of these faults may lead to delayed product intersection and affected the reputation of the manufacturer, increasing time and money costs.
Today is mainly about the PCB fault mode and the PCB failure solution. Here we mainly list the following 15 PCB fault modes, let’s analyze this.

1. PCB crack or bend

Reason: Due to high mechanical or physical stress, printing circuit board components (PCBA) may be ruptured or bent. For example, if the rigid PCBA is placed under repeated vibration or thermal shock, it may fail. In addition, if your curved strength exceeds its ability, even flexible PCBA will break.

PCB crack

Prevention method: Before using PCB during the assembly process, bake PCB and store it in a cabinet with humidity control to remove any water in the naked PCB to avoid impact caused by the later stages of assembly.

2. The assembled PCB components have obvious polarity

Reason: When designing the PCB layout, if the component on the printed circuit board component is not obvious, it may lead to the problem of polar counter -connection. For example, if the battery pole is reversed, the battery and electrical components may be damaged. Printing circuit board components may also fail, and electric shocks may occur.

PCB components have obvious polarity

Prevention method: You can use diode or Schottky diode to reduce the effects of reverse polarity. If you connect the diode with the battery, the circuit will be turned off in the opposite situation, it will prevent any major damage to the printed circuit board component.

3. PCB solder joint break

Reason: The difference between the thermal coefficient and electronic component of the PCB may cause the solder joints to break. If the printed circuit board components are placed in a repeated high or low temperature environment, a failure may occur. Another reason may be manual welding, which makes welded more vulnerable to thermal stress.

PCB solder joint break

Prevention method: It would be much better if you use a special automatic machine to welded electronic components. Before sending the PCB to the assembly process, make sure you have visited inspection.

4. PCB corrosion

Reason: Since there may be some residues during the PCB assembly, there may be some residues, so the printed circuit board component may be corroded. The welding agent is essential to ensure the safe connection of electrical components. However, once contact, it will also cause their corrosion.

Prevention method: Welds are composed of organic acids, such as citric acid or adenic acid. PCB assemblers should ensure that any extra welded agents are eliminated from the PCB surface. This will not help the solder to destroy the metal contact. If the PCB assembler uses a refund welding machine, you should remember to rinse any excess welding agent.

5. Burning or burning electronic components (short circuit)

Reason: During the PCB assembly, short circuit may damage PCB and electronic components. This may be short circuit due to the unexplained welding bridge, humid or accidental events (such as high -current peaks). Short -circuit will cause sudden and sudden damage to components, and may also cause damage to fire and electrical equipment.

Prevention method: Check the short -circuit situation of the PCB surface. For the inner layer, electrical testing is most suitable for the assembly of printing circuit boards. The test mainly checks whether there is short -circuit or opening. In addition, you can compare the obtained readings with the readings obtained from the probe test.
In addition, when designing the PCB layout, PCB assembly personnel must accurately align each layer. In this way, they will be able to work together and avoid any short circuits. You can also reduce the thickness of the PCB template to reduce the deposits of welded paste.

6. Copper weight is not suitable

Reason: For the good current in the printing circuit board component, the weight of the correct copper foil is necessary. If the copper weight is too thin or too thick, it will cause your print circuit board component to fail, which is mainly because the size determination and the width selection of the wiring width when designing the PCB layout.

 

Prevention method: PCB assemblers must follow the copper weight specifications required by PCB engineers. Copper cannot be too thick because it increases costs and cannot be too thin, because they may cause PCB to heat up.

7, component position movement

Reason: In PCB assembly, pick up and place or place components of the circuit board in other automatic machines. If the component is shifted or moved due to the welded weld during welding, the PCB may be faulty. It is mainly because reliable solder joints will not be formed and may cause the road.

Prevention method: PCB assemblers should follow the standard humidity and temperature requirements. They may use more accurate pickup and placing machines to accurately place components. In addition, if you still use more corrosive welding agents, it will improve the weldability of parts, which can keep the electronic components in the original position.

8. The warranty period of electronic components expires

Reason: If any single component in the printed circuit board component fails, it may cause the entire PCB component to collapse, and parts may fail due to reverse selection. If these components are not limited, they will be helpful. In addition, if you choose a low -quality component, it will reduce the service life of the parts, and it may not even be before the warranty period expires.

Prevention method: You should carefully select the component or ask your PCB factory to do so. The parts should not be damaged or the quality should be low (electronic component preparation). In addition, you can directly add components to prepare damage.

9. PCB hot pressure or wet pressure

Reason: Different materials have different expansion rates. Therefore, when a constant a thermal stress is applied, it will damage the solder joint and damage the component. If the wrong copper weight or electroplating problem is used, the stress of thermal factors will increase. Even in the process of manufacturing, the temperature of the assembly PCB room will affect its performance.

Prevention method: PCB assembly personnel must conduct a careful circuit board inspection, prepare, and then clean the necessary cleaning. Pencil rubber rubbing can eliminate any slight corrosion or rust. You can identify the sub -light copper pad through their dark brown. Welds are not sticky to the surface of rust, and must be applied after cleaning, and excess is removed with the welding core.

10. Problems of PCB welding process

Welded welds are very important for the work of electronic circuits, so pay more attention. The most common problems related to soldering are the conditioning conditions for welded pollution and bad processing. The welding agent is a chemical cleaner used before and during the circuit board. Some welded residues will absorb the possible conductive moisture, which will cause short circuit. If the welding process is not set and controlled correctly, the connector can be opened and pollution.

11. PCB uses physical problems of materials

The materials used in PCB often encounters problems that cause the circuit board to fail. In the manufacturing stage, if a layer of PCB is not aligned, it will cause short -circuit, opening and cross -signal lines. If the material has a psychological defect such as breaks, empty holes, and layered, the performance of PCB will be seriously affected. If the material used is not pure, it will also fail.

12. Chemical fluid leaks in electronic components in PCB

The existence of any chemical liquid leaked in the component will severely damage the PCB and cause failure. Most chemicals are removed during the manufacturing process. However, trace elements may be left. Inside the packaging of the component, leaks may occur, which will cause semiconductors or packaging rapidly. This chemical leak will eventually lead to short -circuit or corrosion.

13. PCB component design failed

One of the most common reasons for PCB failures is incorrect components due to insufficient PCB space, power failure or overheating. Space is crucial, especially when the circuit board becomes more complicated and needs to meet harsh requirements. Here are only some examples of errors in the design and manufacturing stage. Don’t forget, you can avoid many such problems by following the correct PCB design rules.
Welding problem
Chemical (fluid) leakage
Component barrier damage
Wrong component placement
Burning component

14, inferior electronic components

It is not so easy to find an electronic component that conforms to the circuit design. Whether it is to ensure packaging or management components, it is very important to find high -quality electronic components when considering PCB assembly and manufacturing.
The tightly placed wiring and channels, poor welding of cold welds, poor connection between circuit boards, insufficient circuit board thickness, and use of counterfeit elements are just some problems that may face.

15. PCB placement environment

PCB is exposed to heat, dust and humidity, accidental impact (falling and falling), and power supply/waves, which may be the cause of circuit board failure. However, the most destructive reason for the premature failure of the circuit board is the electrostatic discharge (ESD) in the assembly stage. Electricity discharge (ESD) is a sudden current flow caused by short circuit or dielectric breakdown between the two electric objects. Static accumulation may be caused by friction charging or electrostatic sensing.