Laboratory for Surface Science and Technology, Department of Electrical and Computer Engineering, University of Maine, Orono, Maine 04469, USA.
ACS Appl Mater Interfaces. 2009 Oct;1(10):2382-9. doi: 10.1021/am900512q.
Real-time, nondestructive methods for monitoring polymer film properties are increasingly important in the development and fabrication of modern polymer-containing products. Online testing of industrial polymer films during preparation and conditioning is required to minimize material and energy consumption, improve the product quality, increase the production rate, and reduce the number of product rejects. It is well-known that shear horizontal surface acoustic wave (SH-SAW) propagation is sensitive to mass changes as well as to the mechanical properties of attached materials. In this work, the SH-SAW was used to monitor polymer property changes primarily dictated by variations in the viscoelasticity. The viscoelastic properties of a negative photoresist film were monitored throughout the ultraviolet (UV) light-induced polymer cross-linking process using SH-SAW delay line devices. Changes in the polymer film mass and viscoelasticity caused by UV exposure produced variations in the phase velocity and attenuation of the SH-SAW propagating in the structure. Based on measured polymer-coated delay line scattering transmission responses (S(21)) and the measured polymer layer thickness and density, the viscoelastic constants c(44) and eta(44) were extracted. The polymer thickness was found to decrease 0.6% during UV curing, while variations in the polymer density were determined to be insignificant. Changes of 6% in c(44) and 22% in eta(44) during the cross-linking process were observed, showing the sensitivity of the SH-SAW phase velocity and attenuation to changes in the polymer film viscoelasticity. These results indicate the potential for SH-SAW devices as online monitoring sensors for polymer film processing.
实时、非破坏性的方法对于监测聚合物薄膜性能在现代含聚合物产品的开发和制造中变得越来越重要。在制备和调节过程中，需要对工业聚合物薄膜进行在线测试，以最大限度地减少材料和能源消耗，提高产品质量，提高生产速度，减少产品报废率。众所周知，水平剪切面声波（SH-SAW）传播对质量变化以及附着材料的机械性能都很敏感。在这项工作中，SH-SAW 被用于监测主要由粘弹性变化决定的聚合物性能变化。使用 SH-SAW 延迟线器件监测负性光刻胶薄膜的粘弹性，在整个紫外（UV）光诱导聚合物交联过程中进行监测。聚合物膜质量和粘弹性的变化由于 UV 暴露产生了在结构中传播的 SH-SAW 的相速度和衰减的变化。基于测量的聚合物涂层延迟线散射传输响应（S(21))和测量的聚合物层厚度和密度，提取了粘弹性常数 c(44)和 eta(44)。发现 UV 固化过程中聚合物厚度减少了 0.6%，而聚合物密度的变化被确定为微不足道。交联过程中 c(44)变化 6%，eta(44)变化 22%，表明 SH-SAW 相速度和衰减对聚合物膜粘弹性变化的敏感性。这些结果表明 SH-SAW 器件作为聚合物薄膜加工的在线监测传感器的潜力。
