A method for fabricating a micro-structured surface of polyimide with open and closed pores

Abstract

A new approach for fabricating open and closed porous structures based on laser processing is presented. Liquid polyimide (PI) was mixed with azodicarbonamide (ADC, ADA) which is a chemical blowing agent (CBA) and mixture was pre-cured in order to fabricate solid PI film. Porous PI was prepared by irradiating PI film mixed with azodicarbonamide. The PI film with azodicarbonamide was etched by laser ablation, and the CBA was decomposed by heat induced by the absorbed laser energy. The higher the laser beam irradiation, the more pores were fabricated due to the resulting increase in CBA decomposition from 27 mJ/cm 2 to 40 mJ/cm 2 per single pulse. Higher fluence at about 50 mJ/cm 2 resulted in fewer and larger open pores, which were formed by the coalescence of small pores. In contrast, a closed porous structure was fabricated at a fluence of less than 1 mJ/cm 2 because PI was barely etched. The proposed method can be sued to create open and closed micro porous structures selectively, and is not limited to thermosetting polymers, but is also effective with thermoplastic polymers.

Fabrication of UV Laser-Induced Porous Graphene Patterns with Nanospheres and Their Optical and Electrical Characteristics

“…Figure 4 k–o shows that, smaller the laser speed, the rougher the surface. From Figure 4 , it can be seen that delamination effect (photochemical effect) and carbonization effect (photothermal effect) can be adjusted by adjusting the laser speed, to adjust the fluence [ 12 , 13 , 14 ]. Since the line pattern is produced in a short time, thermal energy is small, and there is no pulse overlap in the transverse direction; therefore, we created patterns to increase the thermal effects and transverse pulse overlap.…”

“…The so-called laser-induced graphene (LIG) and laser-induced porous graphene (LIPG) on polyimide (PI) film, of which the 2D peak is centered at 2700 cm −1 , like single-layer graphene, is an alternative, because it can be produced quickly and inexpensively, and it is also easy to fabricate patterns with it [ 7 , 8 , 9 , 10 , 11 ]. The interaction of PI and the laser is broadly classified as a delamination effect or a carbonization effect, and it is closely related to the laser fluence [ 12 , 13 , 14 ]. The delamination effect (photochemical effect) occurs when the UV laser power is weak, while the carbonization effect (photothermal effect) occurs as the laser fluence increases.…”