A Wirebonding Instrument for Insulated and Coaxial Wires

A tool has been developed that supports a novel microelectronic integration paradigm whereby interconnects between components are directly established by means of microcoax wire bonding. A near-term use case of the tool is to facilitate rapid prototyping of high-bandwidth systems. When further matured, it will be able to rapidly integrate complex systems with hundreds or thousands of interconnects with minimal design time. Automatic stripping and bonding of coax wires having overall diameters between 50 and 100 μm present an array of process challenges that pose interesting demands on the material system of the wire and the bonding tool. This study reviewed a microcoax bonding system that is currently in development at Draper which is able to strip, feed, and bond microcoax wire. The system utilizes a combination of electric flame-off and thermal reflow to strip outer metal shielding and polymer dielectric layers, respectively. It leverages a rotary wire feed mechanism to precisely control wire position so that predetermined wire lengths can be established. Progress in the design of the wires, tooling, and software control architecture is reviewed.

Microfabrication of Microlens by Timed-Development-and-Thermal-Reflow (TDTR) Process for Projection Lithography

This paper presents a microlens fabrication process using the timed-development-and-thermal-reflow process, which can fabricate various types of aperture geometry with a parabolic profile on a single substrate in the same batch of the process. By controlling the development time of the uncrosslinked negative photoresist, a state of partial development of the photoresist is achieved, called the timed development process. The thermal reflow process is followed after the timed development, which allows the photoresist to regain its liquid state to form a smooth meniscus trench surrounded by a crosslinked photoresist sidewall. Microlens with larger aperture size forms deeper trench with constant development time. With constant aperture size, longer developing time shows deeper meniscus trench. The depth of the meniscus trench is modeled in the relationship of the development time and aperture size. Other characteristics for the microlens including the radius of curvature, focal length, and the parabolic surface profile are modeled in the relationship of the microlens thickness and diameter. Microlens with circular, square, and hexagonal bases have been successfully fabricated and demonstrated where each geometry of the lens-bases shows different fill factors of the lens arrays. To test the fabricated lenses, a miniaturized projection lithography scheme was proposed. A centimeter-scale photomask pattern was photo-reduced using the fabricated microlens array with a ratio of 133, where the smallest linewidth was measured as 2.6 µm.

A Wirebonding Instrument for Insulated and Coaxial Wires

A tool has been developed that supports a novel microelectronic integration paradigm whereby interconnects between components are directly established by way of micro-coax wirebonds. A near term use-case of the tool is to facilitate rapid prototyping of high-bandwidth systems. When further matured, it will lead to the ability to rapidly integrate complex systems with hundreds or thousands of interconnects with minimal design time. Automatic stripping and bonding of coax wires having overall diameters between 50 to 150μm presents an array of process challenges that pose interesting demands on the material system of the wire and the bonding tool. This paper will review a micro-coax bonding system that is currently in development at Draper which is able to strip, feed and bond micro coax wire. The system utilizes a combination of electric-flame-off (EFO) and thermal reflow to strip outer metal shielding and polymer dielectric layers respectively. It leverages a rotary wire feed mechanism to precisely control wire position so that pre-determined wire-lengths can be established. Progress in design of the wires, tooling and software control architecture are reviewed.