| 唐俊,王勇,景鹏渊.电路板的大气污染物典型腐蚀分析及防护[J].装备环境工程,2019,16(7):64-70. TANG Jun,WANG Yong,JING Peng-yuan.Typical Corrosion and Protection Measures Against Airborne Contaminants on Circuit Boards[J].Equipment Environmental Engineering,2019,16(7):64-70. |
| 电路板的大气污染物典型腐蚀分析及防护 |
| Typical Corrosion and Protection Measures Against Airborne Contaminants on Circuit Boards |
| 投稿时间：2019-03-11 修订日期：2019-07-25 |
| DOI：10.7643/ issn.1672-9242.2019.07.015 |
| 中文关键词: 电路板 大气污染物 失效分析 保护涂层 盐雾试验 |
| 英文关键词:printed circuit board assembly airborne contaminants failure analysis protective coatings salt mist test |
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| 中文摘要: |
| 目的 解决电路板在大气污染物环境下的腐蚀失效问题，提升电路板在大气污染环境中的适应性。方法 从器件选型角度，结合厚膜电阻和SMD LED两种电路板典型腐蚀失效案例，利用金相显微镜和扫描电子显微镜对腐蚀部位形貌分析，利用EDS能谱分析仪分析腐蚀元素和确定入侵路径。通过现场一年的应用对比验证，评价不同封装结构物料的抗腐蚀能力。从电路板涂覆涂层角度，利用恒定盐雾和交变盐雾对比试验，评价不同工艺参数涂层的抗腐蚀能力。结果 通过对厚膜电阻和SMD 硅胶封装LED失效样品的分析，硫元素从器件封装靠近镀银构件结构的薄弱点入侵，生成AgS，最终导致器件失效。带有抗硫化镀层的厚膜电阻和环氧树脂封装LED可以有效切断空气中硫元素的入侵路径，避免腐蚀失效发生。另一方面，通过168 h恒定盐雾和144 h交变盐雾试验结果的分析，随着涂覆厚度和材料黏度的增加，样品的抗盐雾能力得到有效提升，器件引脚位置得到更好的防护。结论 通过改变器件封装、增加涂层涂覆的厚度和材料黏度可以有效提高电路板抗大气污染物腐蚀的能力。该研究对电路板防腐蚀物料选型和涂层工艺参数选择提供了参考。 |
| 英文摘要: |
| Objective To solve corrosion failure of printed circuit board assembly (PCBA) caused by atmospheric contami-nation and improve the adaptive capacity of PCBA in environment of atmospheric contamination. Methods Two typical corrosion failure examples were selected in combination with thick-film resistor and SMD LED from the perspective of device selection. The morphology of corrosion was analyzed with metallographic microscopic and scanning electron microscope (SEM). The corrosive elements and paths were analyzed and confirmed by EDS. The corrosion resistance of different component packaging was evaluated through one year of application comparison and verification at site. And the corrosion resistance of the coating was evaluated by constant salt mist and alternating salt mist comparison test from the perspective of PCBA coating. Results After failure analysis of the thick-film resistor and SMD LED, it was found that components were corroded by AgS generated from the sulfur element from the gaps close to the silver coating. Thick-film resistor and SMD LED with anti-vulcanization materials can effectively cut the invasion path of sulfur element in air to avoid corrosion failure. On the other hand, according to the 168 h of constant salt mist test and 144 h of alternating salt mist test, with the increase of the coating thickness and viscosity of varnish, the corrosion resistance of the PCBA increased and the metallic pins got better protection. Conclusion Choosing right packaging component and increasing coating thickness and viscosity of varnish can effectively improve the corrosion resistance of the PCBA. The research provides references for selection of anti-corrosion materials and optimization of coating parameters. |
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