The Removal of Flux Residues from Printed Wiring Assemblies

印制导线组件制造中的关键步骤 （PWAs）是从PWA表面去除焊剂残留物。 这种清洁确保了PWA的电气性能 和后组装涂层的附着力，便于测试 检查装配，并保存机械 衬底的性质。 这种清洁通常是在 使用氯化氟碳化合物的混合物，主要是CFC-113， 和轻质醇如甲醇。 的到来 《蒙特利尔议定书》，氟氯化碳-113用于微电子 清洁正在逐步淘汰。 一种可能的清洁替代方案利用非离子型水溶液。 层状液晶相表面活性剂 接近它们的相转化温度。 这些解决方案 对极性，非极性， 和混合污染物（焊剂残留物可以被认为是混合物 极性和非极性污染物）。 这种低界面 张力允许快速，自发乳化的 当表面活性剂和污染物进入时， 保持联系 表面活性剂溶液表现出低界面张力， 对极性和非极性材料的紧张局势，因此， PWA基板上的接触角将非常低， 快速渗透到组件下方。 表面活性剂 解决方案为助焊剂提供高溶解能力 残留物，因此许多板可以被清洁而不需要 清洗溶剂的再生。 这项研究包括实验和理论工作 研究使用层状和胶束溶液的 非离子表面活性剂作为CFC-113基 PWA的清洁工 这项工作将侧重于发展 从PWA表面去除污染物的理论和 表面活性剂的微观结构与 控制污染物的方法和参数 的拔除. 表面活性剂的结构和组成， 污染物和底物，以及化学物质的影响 清洁溶液中的添加剂，将与 清洁效果。 层状和胶束表面活性剂 解决方案将被研究和解决方案的影响 添加剂对这些相的形成和它们的清洗 将对功率进行评估。 去除中的控制步骤 还将研究PWA表面的污染物。

A key step in the manufacture of printed wire assemblies (PWAs) is the removal of flux residues from the PWA surfaces. This cleaning ensures the electrical performance of the PWA and adhesion of post-assembly coatings, facilitates testing and inspections of the assembly, and preserves the mechanical properties of the substrate. This cleaning is usually done using blends of chlorinated fluorocarbons, primarily CFC-113, and light alcohols, such as methanol. With the advent of the Montreal Protocol, the use of CFC-113 for mictroelectronics cleaning is being phased out. A possible cleaning alternative utilizes solutions of nonionic surfactants in the lamellar liquid crystal phase conformation near their phase inversion temperatures. These solutions exhibit ultralow interfacial tension against polar, nonpolar, and mixed contaminants (flux residue may be considered a mix of polar and nonpolar contaminants). This low interfacial tension allows rapid, spontaneous emulsification of the contaminants to occur when the surfactant and contaminant come in contact. The surfactant solutions exhibit low interfacial tensions against polar and nonpolar materials, hence their contact angle on PWA substrates will be very low, allowing rapid penetration beneath components. The surfactant solutions offer high solubilization capacity for flux residues, so that many boards can be cleaned without requiring regeneration of the cleaning solvent. This research includes both experimental and theoretical work to investigate the use of lamellar and micellar solutions of nonionic surfactants as replacements for CFC-113 based cleaners of PWAs. The work will focus on the development of both the theory of contaminant removal from PWA surfaces and the relationship between the microstructure of surfactant solutions and the parameters which control contaminant removal. The structure and composition of the surfactants, contaminant, and substrate, as well as the effects of chemical additives in the cleaning solution, will be related to the cleaning effectiveness. Lamellar and micellar surfactant solutions will be studied and the effects of solution additives on the fromation of these phases and their cleaning power will be evaluated. The controlling step in the removal of contaminants from PWA surfaces will also be investigated.