What Causes the Failure of the Printed Circuit Board?
In the process of PCB board design and production, engineers need to prevent PCB board design errors during the manufacturing process. When the following faults occur on the printed circuit board, we need to clarify the cause of the fault in order to deal with it more specifically.
1. Short circuit board
For this type of problem, the biggest reason is the incorrect design of the pad. The improper design of the direction of the PCB proofing components will also cause the circuit board to short-circuit and fail to work. If the pin of the SOIC is parallel to the tin wave, it is easy to cause a short circuit accident.
In this case, the direction of the part can be modified to be perpendicular to the tin wave. Since the IPC stipulates that the length of the wire is less than 2mm when the bending angle is too large, this part may drop, so it is easy to cause a short circuit.
2. PCB solder joints become golden yellow
Generally speaking, the solder of the PCB circuit board is silver-gray, but occasionally there are golden solder joints. The main reason for this problem is that the temperature is too high, so you only need to lower the temperature of the tin furnace.
3. There are black granular contacts on the circuit board
The appearance of dark particle contacts on the PCB is mainly due to solder contamination and excessive oxides in the tin, which forms an overly fragile solder joint structure. Care must be taken not to confuse the dark color and low tin content caused by the use of solder.
Another reason for this problem is that the composition of the solder itself used in the manufacturing process has changed, and the impurity content is too high. It is necessary to add a pure tin or replace the solder.
4. PCB components are loose or misaligned
During the reflow soldering process, small parts may float on the molten solder and eventually fall off the target solder joint. The reasons for the displacement or tilt may be insufficient support of the circuit board, reflow oven settings, solder paste problems, human error, etc., which can cause vibration or rebound of the components on the soldered PCB.
5. The circuit board is open
An open circuit occurs when the trace is broken or the solder is only on the pad and not on the component leads. In this case, there is no glue or connection between the component and the PCB. Just like short circuits, these can also occur during production or during welding and other operations.
Stretching the circuit board or other mechanical deformation factors can damage the circuit board or solder joints. In addition, chemicals or moisture can cause the solder or metal parts to wear, causing component wires to break.
6. Welding problems
The following are some of the problems caused by poor welding.
(1) The solder joints are disturbed
The solder moves due to external interference before solidification, which is similar to a cold solder joint, but for different reasons, it can be corrected by reheating.
(2) Cold welding
This happens when the solder cannot melt properly, resulting in rough surfaces and unreliable connections. Cold solder joints can also occur because excessive solder will prevent complete melting. The solution is to reheat the joint and remove the excess solder.
(3) Welding bridge
This happens when the solder crosses and physically connect the two leads together. This may cause accidental connections and short circuits, and when the current is too high, it may cause the components to burn out or the wires to burn out.
7. The badness of the PCB board is also affected by the environment
Because of the structure of the PCB itself, it is easy to damage the circuit board when it is in an unfavorable environment. Changes in ambient temperature can cause the circuit board to deform, which can damage the solder joints, bend the shape of the circuit board, and may also cause the copper wires on the circuit board to break.
On the other hand, moisture in the air can cause oxidation, corrosion, and rust on metal surfaces, such as exposed copper traces, solder joints, pads, and component leads. Dirt, debris, or debris that accumulates on the surface of components and circuit boards can also reduce airflow and component cooling, which can lead to PCB overheating and performance degradation.
8. Human error
Most defects in PCB manufacturing are caused by human error. In most cases, wrong production processes, incorrect component placement, and unprofessional manufacturing specifications result in up to 64% of product defects.
PCB Quick provides a variety of solutions related to printed circuit boards, which can effectively help users solve problems. If you want to learn more about printed circuit boards after reading the above, PCB Quick will provide you with professional advice.
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