Surface roughness, hardness and tensile strength of AA6061-T6 mold manufactured by hot embossing method

Abstract

With advancement in technology, many devices today have to be smaller, more efficient but at the same time, retain its cost effectiveness to remain competitive in this ever-changing world. Microfluidic devices are no exception. Microfluidic devices are already used in a number of domains, including chemistry, biotechnology and medicine [1], where they are known as a ‘lab on a chip’.

Recently, polymers have replaced silicon as the choice of materials to manufacture microfluidic devices due to silicon’s high fabrication cost that involves complex lithography procedures. Hot embossing and micro-injection molding are two popular mass fabrication methods that can mass-fabricate these devices. Both mass fabrication methods are carried out in a similar fashion where a pattern from a mold, which is usually costly to fabricate, is replicated to a polymer substrate. Normally, the molds have microchannels on it and some current methods to create microchannels, are micromilling; micro electrical discharge machining (µEDM); micro electro chemical micromilling (µECM), laser micromachining, cold embossing, superplastic embossing, LIGA and hot embossing to make bulk metallic glass (BMG) mold. Unfortunately, these methods have problems obtaining microchannels with good surface finish [2]. Having a rough surface finish is not ideal for microfluidic devices where flow passages in microns; i.e. from around 1um to hundred of micron are required [1]. There are methods such as LIGA (Lithography, Electroplating, and Molding) that can produce microstructures with high aspect ratio and good surface finish; however it is a very costly and sophisticated method. In order to reach a compromise between manufacturing cost and strength of mold, recently, aluminum alloy 6061 molds have been fabricated using hot embossing method from a silicon master.

In this project, the aim is to evaluate the surface roughness, hardness and tensile strength of AA6061-T6 mold after hot embossing with a silicon master and subsequently, tempering.