How to prevent color change of PI copper plating film in high temperature environment?

Brief introduction

PI copper plated filmIt has a wide range of applications in many high-tech fields, but its color is prone to change in high temperature environments, which not only affects its appearance but may also have a certain impact on its performance. Advanced Institute (Shenzhen) Technology Co., Ltd. has conducted in-depth exploration in the research and application of PI copper plating film. This article will combine relevant research results to explore how to prevent color change of PI copper plating film in high temperature environment.

2、 Reasons for color change of PI copper plated film at high temperature

1. Oxidation reaction of copper
   • Copper is prone to react with oxygen in the air at high temperatures, producing substances such as copper oxide. According to chemical principles, the reaction equation between copper and oxygen is $2Cu{O}_2\stackrel{\mathrm{△}}{\to }2CuO$Copper oxide is black, which can causePI copper plated filmThe color has changed. At high temperatures, the rate of this reaction will accelerate. For example, in $100^{\circ }C$In the environment, after $10$After hours of experimental observation, the surface color of the PI copper plated film without any protective treatment began to slightly darken. Energy spectrum analysis revealed the formation of copper oxide, while the same PI copper plated film at room temperature was subjected to $100$There is only a slight color change like this in the hour.
2. The interaction between PI film and copper
   • The PI film may undergo some structural changes at high temperatures, which may affect its bonding and stability with the copper layer. Research has found that when the temperature rises to $150^{\circ }C$At this time, the molecular chain activity of PI membrane intensifies. Researchers from Advanced Institute (Shenzhen) Technology Co., Ltd. have found through experiments that at this temperature, the chemical bonds inside the PI membrane will form $5\mathrm{\%}$The change in bond energy between the left and right sides may lead to a change in the adhesion between the copper layer and the PI film, making the copper layer more susceptible to oxidation or other chemical reactions, ultimately resulting in a color change.

3、 Methods to prevent color change of PI copper plating film at high temperatures

（1） Surface passivation treatment

1. Selection of passivating agents
   • Similar to the protection of ordinary copper materials, PI copper plating film can also be passivated.Advanced Institute (Shenzhen) Technology Co., LtdThe research team conducted tests on various passivators. For example, passivator A $80^{\circ }C$After processing the PI copper plated film in a high-temperature environment $50$The color change of the film is relatively small during the high-temperature test for hours. Through comparative experiments, PI copper plated films without passivating agents were found to be effective in the same environment $10$After an hour, the color began to change noticeably. And passivator B is $120^{\circ }C$After treating the PI copper plated film at high temperature $30$There is basically no change in color during the hour, and the untreated film remains unchanged $5$There is a noticeable color change from an early age.
2. Passivation process parameters
   • In terms of concentration, when the concentration of passivating agent is $10\mathrm{\%}$It has a good effect on preventing color changes. Taking passivator A as an example, in $100^{\circ }C$At high temperatures, $10\mathrm{\%}$The PI copper plated film treated with a concentration of passivating agent is subjected to $30$The color change is not significant in the hour, and $5\mathrm{\%}$The film treated with a concentration of passivating agent is $20$There is a slight discoloration from an early age. In terms of temperature, it is generally at room temperature $-40^{\circ }C$Soaking with passivating agents has a better effect, and the soaking time depends on the thickness of the film and specific requirements $10-30$Wait for minutes.

（2） Coating protection

1. ORGANIC COATING
   • Using organic coatingsPI copper plated filmProtecting is also an effective method. Advanced Institute (Shenzhen) Technology Co., Ltd. has developed a special organic coating material. exist $150^{\circ }C$Under high temperature conditions, the PI copper plated film coated with this organic coating undergoes $40$The color remains basically unchanged after hours. And the uncoated PI copper plated film $150^{\circ }C$below $5$The color begins to change noticeably as soon as the hour arrives. The thickness of the organic coating is $1-2\mu m$When used, it can provide good protection, but too thick may affect other properties of the PI copper plating film, such as flexibility.
2. inorganic coating
   • Inorganic coatings such as alumina coatings have also been studied for the protection of PI copper plated films. Experimental data shows that $130^{\circ }C$At high temperatures, the coating thickness is $0.5\mu m$The PI copper plated film coated with alumina has undergone $35$The color change is not significant after hours. Uncoated film at the same temperature $8$There is a noticeable color change from an early age. However, the preparation process of inorganic coatings is relatively complex and the cost is also high.

4、 Conclusion

Preventing the color change of PI copper plating film in high temperature environments is a multifaceted issue. Through the study of surface passivation treatment and coating protection methods, combined with the research results and experimental data comparison of Advanced Institute (Shenzhen) Technology Co., Ltd., it can be seen that these methods can effectively prevent the color change of PI copper plating film at high temperatures to varying degrees. In practical applications, appropriate methods can be selected based on specific needs and cost factors. In the future, further in-depth research is needed on the performance change mechanism of PI copper plating film at high temperatures, in order to develop more efficient and economical protection methods.

The above data is for reference only, and specific performance may vary due to production processes and product specifications.