Metal micromolding with surface engineered inserts
- PDF / 726,343 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 40 Downloads / 177 Views
0890-Y03-03.1
Metal micromolding with surface engineered inserts D.M. Cao, J. Jiang, W.J. Meng Mechanical Engineering Department, Louisiana State University, Baton Rouge, Louisiana 70803
Abstract: The LiGA (Lithographie, Galvanoformung, Abformung) technique is a leading micromanufacturing process for making polymer- and metal- based high-aspect-ratio microscale structures. Molding replication is the key LiGA step for economical mass production of metal-based HARMS. Using a hybrid technique, we have fabricated microscale Ta mold inserts. Surface engineering of Ta inserts by electrochemical polishing followed by conformal coating deposition has enabled successful hightemperature micromolding of Al and Cu. In this paper, the molding performance of Ta inserts coated with amorphous hydrogenated carbon based coatings and amorphous silicon nitride based coatings is compared. Issues of maximum molding force, demolding force, and coating durability are addressed. I. Introduction Concepts of next generation cooling of electronic devices often invoke single- or two- phase flow in micro-channels [1]. Commercial implementation of such microscale heat exchangers will in turn demand fabrication technologies which can achieve economical mass production of metal-based, high-aspect-ratio microscale structures (HARMS). The LiGA approach, combining deep lithography based on X-ray or ultraviolet radiation (Lithographie), metal electrodeposition (Galvanoformung), and molding replication (Abformung) [2], represents an important strategy for making metal-based HARMS. Replication of secondary HARMS from primary mold inserts by compression molding is the key LiGA step for achieving economical mass production. Previously, molding replication of HARMS from metallic mold inserts was achieved only in polymer-based materials [3]. More recently, we have demonstrated successful molding replication of metal-based HARMS. Using a micro electrical discharge machining (µEDM) technique, we fabricated HARMS mold inserts out of Ta [4, 5]. With an inductively coupled plasma (ICP) assisted hybrid chemical/physical vapor deposition (CVD/PVD) technique [6, 7], we demonstrated conformal deposition of nanostructured ceramic coatings over LiGA fabricated Ni HARMS [8, 9]. Relationships between the nanoscale structure, mechanical properties, and tribological characteristics were studied in amorphous hydrogenated carbon (a-C:H) based coatings [10, 11, 12] and amorphous silicon nitride (a-Si:N) based coatings [13, 14, 15]. Combining such bulk and surface engineering of HARMS mold inserts, we demonstrated successful molding replication of HARMS in Zn [16], Pb [16, 17], Al [18], and Cu [4]. In this paper, we focus on the effects of insert surface coatings on the performance of metal micromolding. Micromolding of Al and Cu was carried out with Ti-containing hydrogenated carbon (Ti-C:H) coated and a-Si:N coated inserts and their molding performance was compared. II. Experimental procedures Four microscale mold inserts were used in this series of experiments. The insert
Data Loading...
