CONFORMAL COATING PROCESS CONTROL AS IT RELATES TO TEMPERATURE AND HUMIDITY

摘要

In the face of an ever-expanding high volume global electronics manufacturing industry, a renewed interest in lower volume, high reliability products has occurred in North America. This is in large part due to the nontransferability of these products to overseas manufacturers. Because of this factor, it has become increasingly important to monitor the process windows and subsequent quality levels of the manufacturing of these products. This statement is especially true with conformal coating applications. Given the fluid nature of conformal coat, this process is very susceptible to its exposed dispensing application and environmental parameters. To further complicate the task of controlling this process, the dispensing application and environmental parameters maintain a strong variable relationship. Consequently, the process window for performing this application is quite small and requires significant process calibration. This paper will present a series of Design of Experiments related to the important variables of the conformal coating process. Specifically, data and conclusions will be provided to correlate optimal environmental characteristics for spraying conformal coat with some emphasis on relating environmental parameters to the viscosity and specific gravity of the material. From the experiments presented within this paper, the conformal coating material to be evaluated will be acrylic. Acrylic conformal coat has been chosen for the evaluation because of its two-part material characteristic. The deliverables of the paper will encompass conclusions about optimal process setup and ultimate coating reliability from the aspect of this material type and its subsequent process parameters.