What is Circumferential Separation
Circumferential separation is a type of crack or separation that occurs in the plating material surrounding a plated through hole. This type of separation is characterized by a crack that extends around the entire circumference of the hole, resulting in a complete separation of the plating material. The occurrence of circumferential separation can be attributed to various factors, including the PCB manufacturing processes and the quality of the raw materials used.
To prevent circumferential separation, PCB fabricators should implement effective and consistent drilling processes, ensuring that the holes are properly formed without causing any cracks or separations. It is also crucial to reduce the resin content in the stack-up, as excessive resin can lead to increased stress and potential separation. Additionally, a good desmear process should be employed to remove any debris or contaminants that could contribute to separation issues.
Providing an adequate copper border around the plated through holes is essential for supporting the plating material and allowing for proper resin venting. This helps to minimize the risk of circumferential separation. Certain materials with inorganic fillers and more chemically resistant resin systems may be more susceptible to debris issues, which can increase the likelihood of circumferential separation between plating layers.