How can high-temperature resistant protective film achieve stable shielding and residue-free protection of gold plating during high-temperature PCB soldering?
Publish Time: 2026-06-10
In high-temperature PCB soldering processes, gold plating is typically used to improve conductivity and oxidation resistance. However, in subsequent reflow soldering, wave soldering, or localized heat treatment, some areas do not need to participate in the soldering reaction. In this case, the role of high-temperature resistant protective film is crucial. It needs to provide stable shielding of the gold plating under high-temperature conditions and ensure residue-free peeling after the process to guarantee circuit accuracy and surface quality.
1. Achieving Thermally Stable Shielding Through High-Temperature Substrate Structure
PCB soldering processes typically occur in high-temperature environments between 200°C and 300°C. Ordinary protective materials are prone to softening, shrinking, or decomposition, leading to shielding failure. High-temperature resistant protective film typically uses polyimide (PI) or modified PET as the substrate, materials with excellent thermal and dimensional stability.
2. Achieving High-Temperature Impermeable Protection Through Optimized Adhesive System
Besides the substrate itself, the adhesive layer is a key factor determining the shielding effect. If the adhesive layer flows or seeps at high temperatures, it may contaminate the gold plating surface, affecting the quality of subsequent soldering. High-temperature resistant protective films typically use silicone or acrylic modified adhesive systems, with cross-linked structures to improve their heat resistance and chemical stability. During high-temperature soldering, these adhesive layers maintain stable adhesion, neither losing adhesion due to temperature increases nor migrating, effectively preventing solder spatter and flux contamination, ensuring a clean gold plating surface.
3. Controlling Thermal Expansion Matching to Reduce Warpage and Stress Failure
In high-temperature environments, differences in the coefficients of thermal expansion between different materials can easily cause the protective film to wrinkle or peel off, thus compromising its shielding effect. Therefore, the design of high-temperature resistant protective films requires optimizing the thermal expansion matching between the substrate and the adhesive layer. By using a low-thermal-expansion PI film combined with a flexible adhesive layer structure, overall stress balance can be maintained during temperature changes, allowing the protective film to deform slightly in sync with the PCB substrate, thereby avoiding localized failure caused by thermal stress concentration and ensuring shielding continuity and stability.
After soldering, the protective film must be able to be quickly and completely peeled off the PCB surface without leaving any adhesive or contaminants, otherwise it will affect subsequent electrical performance and appearance quality. By optimizing the cohesive force and interfacial adhesion of the adhesive, it maintains "controlled adhesion" characteristics even at high temperatures, enabling complete film removal under low peel force conditions. Simultaneously, a low-residue formulation design prevents the adhesive layer from decomposing or migrating after high-temperature exposure, ensuring a clean and uncontaminated gold plating surface after peeling.
Through a high-temperature stable substrate, a heat-resistant adhesive system, optimized thermal expansion matching, and a residue-free peeling design, the high-temperature resistant protective film provides stable shielding and clean protection for the gold plating layer during high-temperature PCB soldering. This not only improves the reliability of the soldering process but also ensures the long-term performance and stability of electronic products.
