Analysis of Causes for PCB Delamination and Blistering

　　According to the IPC-A-610 standard,Blistering is a form of delamination characterized by localized swelling and separation between any layers of the laminated base material, or between the base material and the conductive foil or protective coatings.
　　Delamination refers to the separation that occurs between layers of the base material, between the base material and conductive foil, or between other internal interfaces within the PCB.

Major Types of Delamination and Their Causes
  Delamination Between Copper Foil and PP Resin

　　Key Factors:

　　•Insufficient adhesion strength: A small contact area between the copper foil and the resin results in low peel strength.
　　•Excessive thermal expansion: The base material undergoes thermal expansion beyond its tolerance duringsoldering processes.

  Delamination Between PP Sheets
　　•Insufficient pre-lamination dwell time: Applying full pressure too early causes excessive resin flow, resulting in resin starvation and potential delamination.
　　•Excessive pre-lamination dwell time: Delayed full pressure application prevents complete evacuation of air and volatiles, leading to voids that expand under heat and cause delamination.

　　•Contaminants or foreign particles: Impede resin polymerization and adhesion between PP layers, increasing the risk of delamination under thermal stress.

  Delamination Between PP Sheet and Brown Oxide Surface
　　After brown oxide treatment, the inner layer core develops a uniform brown organic-metallic layer on the copper surface, which enhances adhesion between the copper and PP resin.If this microstructure is damaged (e.g, due to scratches or abnormal surface treatment), the bonding strength between the brown oxide-treated copper and PP resin is weakened, making the interface susceptible to delamination when exposed to thermal expansion.