| LI Yuzhu,ZENG Xiaotong,LIU Hongliang,ZHAO Fangchao,FANG Bo,LIU Jie.Corrosion Failure Behavior of Printed Circuit Board (PCB) with Different Treated Surfaces in Salt Spray Environment[J],54(4):96-109 |
| Corrosion Failure Behavior of Printed Circuit Board (PCB) with Different Treated Surfaces in Salt Spray Environment |
| Received:September 03, 2024 Revised:November 06, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.04.007 |
| KeyWord:printed circuit board salt spray test polarization curve failure behavior electrochemical migration |
| Author | Institution |
| LI Yuzhu |
School of Chemistry and Chemical Engineering, Yantai University, Shandong Yantai , China |
| ZENG Xiaotong |
School of Chemistry and Chemical Engineering, Yantai University, Shandong Yantai , China |
| LIU Hongliang |
School of Chemistry and Chemical Engineering, Yantai University, Shandong Yantai , China;Shandong Laboratory of Yantai Advanced Materials and Green Manufacturing, Shandong Yantai , China |
| ZHAO Fangchao |
Weathering Test and Research Center of Science Technology and Industry for National Defense, Southwest Technology and Engineering Research Institute, Chongqing , China |
| FANG Bo |
School of Chemistry and Chemical Engineering, Yantai University, Shandong Yantai , China |
| LIU Jie |
School of Chemistry and Chemical Engineering, Yantai University, Shandong Yantai , China |
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| Abstract: |
| The surface of printed circuit board (PCB) is prone to electrochemical corrosion due to the synergistic effect of environmental factors. As one of the common pollutants, Cl− is more likely to adsorb on the metal surface and penetrate into the metal substrate, thus causing serious damage to the metal substrate. In this experiment, the corrosion failure behaviors and mechanisms of copper clad laminate (PCB-Cu), silver-immersed printed circuit board (PCB-ImAg) and tin−immersed printed circuit board (PCB-ImSn) in salt spray environment were investigated. The neutral salt spray test was carried out to PCB-Cu, PCB-ImAg and PCB-ImSn. The corrosion failure mechanism of PCB in salt spray environment was analyzed from the aspects of electrochemical impedance spectroscopy (EIS), polarization curve, surface corrosion morphology and composition of corrosion products. In the neutral salt spray environment, after 168 h of the salt spray test, the impedance value of PCB-Cu increased from 5.20×103 Ω∙cm2 to 2.07×104 Ω∙cm2, while the reciprocal of charge transfer resistance gradually decreased. Concurrently, the self-corrosion current density decreased from 1.454 µA/cm2 to 0.036 µA/cm2. The corrosion products, mainly composed of Cu2O and Cu2Cl(OH)3, accumulated on the surface of PCB-Cu, which hindered the transmission of corrosive particles to a certain extent. The impedance value of PCB-ImAg increased from 5.13×103 Ω∙cm2 to 1.13×104 Ω∙cm2, with a corresponding increase in self-corrosion current density from 0.759 µA/cm2 to 2.179 µA/cm2. The Ag layer was gradually damaged, and the corrosive particles accumulated on the surface of exposed Cu substrate, weakening the protective effect of the corrosion product layer, thereby intensifying corrosion. At this time, corrosion products such as Cu2O, Cu2Cl(OH)3 and Ag2O were gradually formed and accumulated continuously, delaying the corrosion to a certain extent. Conversely, for PCB-ImSn, the impedance value was reduced from 1.72×105 Ω∙cm2 to 1.35×105 Ω∙cm2, while the reciprocal of charge transfer resistance increased slightly, and the self-corrosion current density increased from 0.016 µA/cm2 to 0.069 µA/cm2. With the extension of salt spray test time, the corrosion products gradually accumulated, and a dense layer of corrosion products formed on the surface, playing a role in delaying corrosion. After the voltage was applied, the anode of PCB was seriously corroded, while the corrosion products on the cathode edge of PCB-ImSn and PCB-Cu grew towards the anode. The results indicated that with the prolonged exposure to salt spray test, the corrosion products on the surface of PCB-Cu accumulated continuously, and the corrosion product layer gradually thickened, thereby delaying corrosion. The corrosion products on the surface of PCB-ImSn gradually dissolved and became thinner and more stable and dense corrosion product layers gradually formed. However, the surface of PCB-ImAg was gradually damaged, exposing the Cu substrate and forming a galvanic system with large cathode and small anode, which led to the increase of corrosion rate of Cu substrate, and the protective effect of corrosion products was weakened. Moreover, the enrichment phenomenon of Cu appeared in anode region of the three PCB samples. The electrochemical migration sensitivity of PCB-ImSn was high, while the electrochemical migration sensitivity of PCB-ImAg was relatively low. |
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