CO2 snow cleaning of miniaturized parts

Abstract

The surface cleaning of components with sub-millimeter features poses a challenge in many applications. Challenges may be strong particle adhesion at the microscale, the difficult handling of the samples, the small size of the adhering particles, and unfavorable geometry. However, components often need cleaning before processing, assembly, packaging, applications, and measurement can proceed. Previous evaluations of CO2 snow cleaning almost exclusively refer to the cleaning of smooth, flat or convex surfaces; typically examined samples were wafers and optical components. In this paper, we studied the CO2 snow cleaning of complex surface shapes as found on microgears. The performance of CO2 snow cleaning is compared with ultrasonic cleaning and a high-speed air jet. The evaluation of the 72 cleaning experiments is based on the optical microscope images of the four investigated samples before and after cleaning. Results show that CO2 snow cleaning removed more than 95 % of the micrometer-sized contamination from our test samples. Ultrasonic cleaning removed 88 % of the particles and the high-speed air jet removed 74 % of the particles.