Minimization of faults is the main goal of PCB manufacturers serving critical and not so critical industries. An in-depth understanding of common faults, their root causes, and prevention is the one way to ensure the high-quality of PCB assembly. Owing to the increasing density of these issues there are high chances of a PCB failure. If the care is not taken, then this will affect the functionality of the final product. Would you like to know about six common PCB manufacturing errors? Or how to prevent these fabrication errors? This post will answer these questions in detail.
6 Common PCB Assembly Defects That Should Be Avoided
The following are some common defects found in the printed circuit board assemblies
and their corrective actions.
Solder Bridges: This is the most common type of defect found in the PCB assembly. Solder bridging, sometimes referred to as shorts, occurs when a solder crosses one lead to another or have an abnormal connection between two or more adjacent traces. They can be tiny in size and hard to detect. If these shorts are not detected during the circuit board inspection, then it can cause serious damage to the assembly, such as blow-up or burn-up of components and traces. However, this issue can be avoided using several ways, such as adding solder mask between the pads, ensuring a zero gaps between the PCB and stencil, and so on.
Plating Voids: Plated through holes are important holes on the printed circuit board, as they carry electricity from one side of the board to the other side through the holes. The walls of these holes are electroplated during the PCB fabrication process. Before electroplating, the circuit board is made conductive from the top to bottom by copper deposition. In this process, the electroless copper is made to adhere to the edges of the circuit board and within the holes. The problems with copper deposition give rise to plating voids, which means the walls are not coated evenly with copper. These holes may affect the flow of electricity. Plating voids may be caused due to a variety of reasons such as material contamination, air bubbles in the material, contaminated holes, and so on. So, the defects caused due to air bubbles, contamination, and insufficient cleaning can be avoided by cleaning the material before drilling. Also, other defects can be avoided by following the directions provided by the manufacturer.
Non-wetting: Non-wetting, also known as dewetting, occurs to alloy solder joints, which are not extended to the PCB pads. Thus, they do not obtain a great solder joint fillet. Non-wetting can occur when the solder partially covers a board surface while leaving exposed copper behind. This can directly impact the quality of solder joints. This PCB issue can be avoided by paying close attention to the storage environment of PCB components. Make sure they meet the standards with regards to humidity and temperature. Also, avoid using a PCB that has been stored for a long time without any protective cover or sheet.
Acid Traps: Via positioning may bring a risk of solder leakage through the pads at the time of assembly. This can be solved using a non-conductive epoxy or by applying the solder mask over the holes.
Physical Damage: Failure of PCB is linked to physical damage, which is caused due to environmental stresses or during the SMT manufacturing process. Most common cause of PCB failure is dropping a circuit board in a prototyping phase. The damage to the physical components or pieces is not easily visible, and they are not repairable either. Thus, there is no other option except replacing the PCB.
Electromagnetic Issues: Electromagnetic interference and electromagnetic compatibility are two common terms associated with PCBs. The term electromagnetic compatibility (EMC) is the term used for generation and propagation of electromagnetic energy, whereas, electromagnetic interference refers to the damaging effect of EMC. These issues arise due to some possible design flaws. Electromagnetic interference can be reduced by increasing the ground area of the PCB.
Printed circuit boards designing
needs excellent technical skills, as well as precision. Any single mistake in the PCB layout may result in a huge loss. This is why the care should be taken when designing the printed circuit board. Are you planning to build your printed circuit board? In such cases, it is always better to approach industry experts. With vast industry experience, Sierra Assembly Technology Inc. offers best PCB solutions while considering your specific requirements.