PCB board copper blistering causes and preventive measures and solutions

The phenomenon of PCB copper blistering is not uncommon in the electronics industry, and it will bring potential risks to product quality and reliability. Generally, the root cause of copper blistering is the insufficient bonding between the substrate and the copper layer, which is easy to peel off after heating. However, there are many reasons for insufficient bonding. This article will deeply explore the causes, prevention measures and solutions of PCB copper blistering to help readers understand the nature of this problem and take effective solutions.

First, PCB board copper skin blistering reason

Internal factors

(1) Circuit design defects: unreasonable circuit design may lead to uneven current distribution and local temperature rise, thus causing copper blistering. For example, factors such as line width, line spacing, and aperture are not fully considered in the design, resulting in excessive heat generated during the current transmission process.

(2) Poor board quality: The quality of the PCB board does not meet the requirements, such as insufficient adhesion of the copper foil and unstable performance of the insulation layer material, which will cause the copper foil to peel off from the substrate and form bubbles.

external factors

(1) Environmental factors: air humidity or poor ventilation, will also make the copper blistering, such as PCB boards stored in a humid environment or manufacturing process, the moisture will penetrate between the copper and the substrate, so that the copper blistering. Furthermore, poor ventilation during the production process can lead to heat accumulation and accelerate copper blistering.

(2) Processing temperature: During the production process, if the processing temperature is too high or too low, the surface of the PCB will be in a non-insulated state, resulting in the generation of oxides and the formation of bubbles when current flows through. Uneven heating can also cause the surface of the PCB to deform, thus forming bubbles.

(3) There are foreign objects on the surface: The first type is oil, water, etc. on the copper sheet, which will make the surface of the PCB non-insulated, causing oxides to form bubbles when current flows through; the second type is bubbles on the surface of the copper sheet, which will also cause bubbles on the copper sheet; the third type is cracks on the surface of the copper sheet, which will also cause bubbles on the copper sheet.

(4) Process factors: in the production process, may increase the roughness of the orifice copper, may also be contaminated with foreign matter, there may be orifice leakage of the substrate and so on.

(5) Current factor: Uneven current density during plating: Uneven current density can lead to excessive plating speed and bubbles in certain areas. This may be caused by uneven flow of electrolyte, unreasonable electrode shape or uneven current distribution;

(6) Inappropriate cathode to anode ratio: In the electroplating process, the ratio and area of the cathode and anode should be appropriate. If the cathode-anode ratio is not appropriate, for example, the anode area is too small, the current density will be too large, which will easily cause bubbling phenomenon.

2. Measures to prevent blistering of copper foil on PCB

(1) Optimize circuit design: During the design phase, factors such as current distribution, line width, line spacing, and aperture should be fully considered to avoid local overheating caused by improper design. In addition, appropriately increasing the wire width and spacing can reduce current density and heat generation.

(2) Choose high-quality boards: When purchasing PCB boards, you should choose suppliers with reliable quality to ensure that the board quality meets the requirements. At the same time, strict incoming inspection should be carried out to prevent copper blistering due to board quality problems.

(3) Strengthen production management: formulate strict process flow and operating specifications to ensure quality control in all links of the production process. In the pressing process, it is necessary to ensure that the copper foil and the substrate are fully pressed together to prevent air from remaining between the copper foil and the substrate. In the electroplating process, 1. Control the temperature during the electroplating process to avoid excessively high temperatures. 2. Ensure that the current density is uniform, reasonably design the electrode shape and layout, and adjust the flow direction of the electrolyte. 3. Use high-purity electrolyte to reduce the content of pollutants and impurities. 4. Ensure that the ratio and area of the anode and cathode are appropriate to achieve uniform current density. 5. Perform good substrate surface treatment to ensure that the surface is clean and activated thoroughly. In addition, the humidity and ventilation conditions of the production environment should be kept good.

In short, strengthening production management and standardizing operations are the key to avoiding blistering of copper foil on PCB boards. I hope that the content of this article can provide useful reference and help to the majority of practitioners in the electronics industry in solving the problem of blistering of copper foil on PCB boards. In future production and practice, we should pay attention to detail control and standardized operations to improve product quality and reliability.