Main Failure Modes of Circuit Board
Printed circuit boards (PCB) are the fundamental components that electronics depend on for seamless functionality. These small but essential boards are found in all sorts of products, from simple consumer gadgets to intricate industrial machines. However, just like any other product, PCBs are susceptible to malfunctions and defects that could impede or destroy their operation. These issues can be caused either during production or after a device is in the field. Regardless of the reason for the problem, a PCB contract manufacturer can diagnose the issue and provide preventative solutions that will ensure your equipment is up and running.
Most of the time, circuit board problems are caused by environmental factors rather than manufacturing flaws. Dust, moisture and insect infestation are common causes of circuit board failure that can be prevented with proper maintenance and cleaning. For example, excessive dust buildup can cause short circuits by bridging unneeded connections or stopping needed ones from functioning. Moisture and ant or mosquito infestations can also lead to PCB failure, especially if the equipment is used in a humid or hot environment.
Other problems can occur because of electrical overstress, relay issues or ground loops. Relays, which control the flow of electricity in a circuit board, can be damaged by overheating or electrical surges that melt plastic encapsulations and harm coils. Resistor and capacitor issues can also lead to system failure. If the component is a semiconductor, electrical overstress can cause it to become damaged and short circuit or even explode.
What Are the Main Failure Modes of Circuit Board?
In addition to environmental stress, the materials and processes involved in producing a circuit board can lead to defects that can compromise the integrity of the finished product. For example, redeposited metal fragments can bridge unrelated conductors or penetrate coatings and leave them vulnerable to arcing. Insufficient solder masking can also remove insulation layers separating adjacent metallic surface-mount landing pads leaving them vulnerable to condensation or voltages exceeding their insulation thresholds. Tight pattern density controls and aggressive wash cycles can reduce defect rates.
Poor etching procedures can also result in a number of defects. The copper foil that carries the traces on the laminate substrate can be etched too thin or too thick for optimal performance. Likewise, copper that is not correctly weighted can hinder the electrical flow of the circuit. Solder flux corrosion can also damage the metals with which it comes into contact.
One of the most common failure modes of PCB is plate through hole barrel cracking, which occurs because of differential expansion between copper plating and the out-of-plane coefficient of thermal expansion (CTE) of the laminate. This is exacerbated by improper surface finish selection and contamination from the environment. Other common defects include oxidation, condensation, incorrect copper weight, and more. These can all be avoided with careful adherence to the design specifications by the PCB fabricator and proper maintenance of the finished product in the field. A PCB can also be damaged by mechanical stress if it is exposed to vibrations or repeated shocks.
