Internal factors
(1) Circuit design defects: Unreasonable circuit design may lead to uneven current distribution, local temperature rise, and thus cause copper blistering. For example, factors such as line width, line spacing, and aperture were not fully considered in the design, resulting in excessive heat generation during current transmission.
(2) Poor board quality: The PCB board quality does not meet the requirements, such as insufficient adhesion of copper foil, unstable performance of insulation layer material, etc., which can cause the copper skin to peel off from the substrate and form bubbles.
Extrinsic factors
(1) Environmental factors: High air humidity or poor ventilation can also cause copper foil to bubble. For example, when PCB boards are stored or manufactured in a humid environment, moisture can penetrate between the copper foil and the substrate, causing the copper foil to bubble. Furthermore, during the production process, poor ventilation can lead to heat accumulation and accelerate the foaming of copper sheets.
(2) Processing temperature: During the production process, if the processing temperature is too high or too low, the PCB surface will be in a non insulating state, resulting in the formation of oxides and bubbles when current flows through. Uneven heating can also cause deformation on the surface of the PCB board, resulting in the formation of bubbles.
(3) Foreign objects on the surface: The first type of copper foil has oil stains, moisture, etc., which can cause the PCB surface to be in a non insulating state, resulting in the formation of oxides and bubbles when current flows through it; The second type of copper skin has bubbles on its surface, which can also cause the copper skin to bubble; The third type of copper skin has cracks on the surface, which can also cause the copper skin to bubble.
(4) Process factors: During the production process, there may be an increase in the roughness of the copper holes, contamination of foreign objects, and possible leakage of the substrate from the holes.
(5) Current factor: During the electroplating process, uneven current density can cause the electroplating speed to be too fast in certain areas, resulting in the formation of bubbles. This may be caused by uneven flow of electrolyte, unreasonable electrode shape, or uneven current distribution;
(6) Inappropriate ratio of anode and cathode: During the electroplating process, the ratio and area of the anode and cathode should be appropriate. If the ratio of anode to cathode is not appropriate, for example, if the anode area is too small, the current density will be too high, which can easily cause foaming