Shantonu Biswas

A First Implementation of an Automated Reel-to-Reel Fluidic Self-Assembly Machine

A first automated reel-to-reel fluidic selfassembly process for macroelectronic applications is reported. This system enables high-speed assembly of semiconductor dies (15 000 chips per hour using a 2.5 cm-wide web) over large-area substrates. The optimization of the system (>99% assembly yield) is based on identification, calculation, and optimization of the relevant forces. As an application, the production of a solid-state lighting panel is discussed, involving a novel approach to apply a conductive layer through lamination.

Surface Tension Directed Fluidic Self-Assembly of Semiconductor Chips across Length Scales and Material Boundaries

This publication provides an overview and discusses some challenges of surface tension directed fluidic self-assembly of semiconductor chips which are transported in a liquid medium. The discussion is limited to surface tension directed self-assembly where the capture, alignment, and electrical connection process is driven by the surface free energy of molten solder bumps where the authors have made a contribution. The general context is to develop a massively parallel and scalable assembly process to overcome some of the limitations of current robotic pick and place and serial wire bonding concepts. The following parts will be discussed: (2) Single-step assembly of LED arrays containing a repetition of a single component type; (3) Multi-step assembly of more than one component type adding a sequence and geometrical shape confinement to the basic concept to build more complex structures; demonstrators contain (3.1) self-packaging surface mount devices, and (3.2) multi-chip assemblies with unique angular orientation. Subsequently, measures are discussed (4) to enable the assembly of microscopic chips (10 μm–1 mm); a different transport method is introduced; demonstrators include the assembly of photovoltaic modules containing microscopic silicon tiles. Finally, (5) the extension to enable large area assembly is presented; a first reel-to-reel assembly machine is realized; the machine is applied to the field of solid state lighting and the emerging field of stretchable electronics which requires the assembly and electrical connection of semiconductor devices over exceedingly large area substrates.

Millimeter Thin and Rubber‐Like Solid‐State Lighting Modules Fabricated Using Roll‐to‐Roll Fluidic Self‐Assembly and Lamination

A millimeter thin rubber-like solid-state lighting module is reported. The fabrication of the lighting module incorporates assembly and electrical connection of light-emitting diodes (LEDs). The assembly is achieved using a roll-to-roll fluidic self-assembly. The LEDs are sandwiched in-between a stretchable top and bottom electrode to relieve the mechanical stress. The top contact is realized using a lamination technique that eliminates wire-bonding.

Approaching Roll-to-Roll Fluidic Self-Assembly: Relevant Parameters, Machine Design, and Applications

This paper presents the implementation of an automated roll-to-roll fluidic self-assembly system based on the surface tension driven self-assembly with applications in the field of macroelectronics. The reported system incorporates automated agitation, web motion, component dispensing, and recycling. The process enables the assembly and electrical connection of semiconductor dies/chips in a continuous and parallel fashion over wide area substrates. At present, the method achieves an assembly rate of 15000 chips per hour and an assembly yield exceeding 99%, testing assembly of standard square-shaped dies, 300-1000 μm size. Scaling the system to any desired throughput is possible due to the parallel manner of selfassembly. The identification and the modeling of the relationship between process parameters and forces have been studied and experimentally verified by testing the effect of the web angle, agitation on assembly, and detachment rates. As an application, we demonstrate the realization of a solid-state lighting module. This particular application requires the assembly of a conductive multilayer sandwich structure, which is achieved by combining the introduced assembly process with a novel lamination step.

Metamorphic hemispherical microphone array for three-dimensional acoustics

This article describes the realization of a metamorphic stretchable microphone array, which can be inflated by air to morph from a planar to a hemispherical shape. The array undergoes morphological changes to adjust their receive characteristic. To realize this device, a metamorphic printed circuit board technology (m-PCB) is described. The resulting products are millimeter-thin stretchable silicone embedded and electrically interconnected electronic structures with mechanical properties, which resemble a silicone membrane. The microphone array is used to localize a sound source in a 3D space. The results of the planar orientation (resting shape), and the 3D hemispherical orientation after air inflation are compared. The inflated hemispherical microphone array proofs to be better for 3D acoustic localization and/or beam-forming.