Hot embossing characteristics of PEEK compared to PC and PMMA

Abstract

Development of low cost manufacturing processes for the MEMS and the MOEMS is important for their commercialization. A micro hot embossing process is used to make optical and Bio devices with Polycarbonate (PC) and Polymethylmetacrylate (PMMA) materials. In this paper, outline of an optical switch with 8/spl times/8 mirrors is introduced and the optical switch used Polyetheretherketone (PEEK) sheet, which has high mechanical properties, high chemical resistance and high hydrolysis resistance at elevated temperature, is embossed with a developed micro hot embossing machine by using a mould made by electroforming. Embossing force and temperature have been changed up to 10 kN and 600 K respectively. After the embossing, the minimum thickness of the PEEK has changed from 300 um to 100 um. The shapes and sizes of replicated mirrors are evaluated and compared with the PC and the PMMA. Glass transition temperature (Tg) of the PEEK (416 K) is almost same as the PC (423 K) and higher than the PMMA (378 K). However, the mechanical strength of the PEEK at the elevated temperature is higher than the PC and the PMMA. Therefore the PEEK needs higher embossing force and temperature compared to the PC and the PMMA. But the PEEK is very easy to remove from the mould due to coefficient of linear thermal expansion at elevated temperature is higher than the PC and the PMMA.