Study on micro hot embossing of low temperature co-firable ceramic green substrates

Abstract

Multi-layered ceramic substrates with embedded micro patterns are becoming increasingly important, for example, in harsh environment electronics, enabling microsystems and microfluidic devices. Fabrication of these embedded micro patterns, such as micro channels, cavities and vias, is a challenge. This study focuses on the process aspects of patterning micro features on low temperature co-firable ceramic (LTCC) green substrates using micro hot embossing. Green ceramic tapes that possessed near-zero shrinkage in the x-y plane were used, six layers of which were stacked and laminated as a substrate. The process parameters that impact on the embossing fidelity were investigated and optimized in this study. Micro features with channel-width as small as several micrometers were formed on green ceramic substrates. The dynamic thermo-mechanical analysis indicated that extending the holding time at a certain temperature range would harden the substrates with little effect on improving the embossing fidelity. Ceramic substrates with embossed micro patterns were obtained after co-firing; the shrinkage ratios of the embossed depth and channel-width were 8-15 and 12-17%, respectively. The changes of pitches between two embossed channels were within ±1.0% due to the interlocking effect of the ceramic tapes.

Solvent-assisted low pressure room temperature lamination of low temperature cofirable ceramic green tapes for formation of embedded micro channels

“…Micro channels and cavities can be created on the first ceramic green substrate by mechanical punching (Wang et al 2006) or micro embossing (Shan et al 2009). The process procedure of using mechanical punching was to punch individual green tapes first, followed by stacking and laminating; this would lead to unsmoothed sidewalls of micro channels and cavities.…”

“…This would result in micro-sized patterns with smooth sidewalls. In this study, micro embossing was performed using an electroplated Ni mould and commercially available equipment (Shan et al 2009). By using a typical embossing process (temperature T = 80°C, pressure P = 10 MPa), micro channels with channel width ranging from 25 to 1,000 lm were created on ceramic green substrates.…”

“…1: (a) The first ceramic green substrate was prepared by laminating four sheets of ceramic green tapes under conventional lamination process (10 MPa; 75°C), and a second ceramic green substrate (two tapes) was prepared in the same way. (b) Micro channels with channel width ranging from 25 to 1,000 lm were created on the first ceramic green substrate by using micro embossing (Andrijasevic et al 2007;Shan et al 2009). (c) The selected solvent was distributed on surface of either the first or the second substrate.…”

Overview on low temperature co-fired ceramic sensors

“…There are four main groups of the LTCC machining methods: punching [40][41][42][43], laser cutting [44][45][46][47][48][49], milling [2,50] and embossing [51][52][53][54]. The most widely used are punching and laser cutting.…”