3D printing has seen much progress in recent decades with the introduction of new materials and printing techniques. This article describes the combination of a novel, stereolithography (SLA) based method for structural material buildup with laser induced forward transfer (LIFT) printing of conductive and resistive elements and placement of commercial active and passive components for the additive manufacturing of 3D functional electronic devices. The structural material is composed of dry film photoresists that are exposed and laminated to form a stack which is later developed to remove unexposed area and reveal the desired free form shape. Interconnection using pillar penetration between the structural layers is described in detail. Several examples of functional objects (lamp, microphone) demonstrate the practicality of this novel, multi material printing method.
In this work, we present the advantages of driving a multichannel acousto-optical deflector (AOD) with a digitally synthesized multifrequency RF signal. We demonstrate a significant bandwidth broadening of ∼40% by providing well-tuned phase control of the array transducers. Moreover, using a multifrequency, complex signal, we manage to suppress the harmonic deflections and return most of the spurious energy to the main beam. This method allows us to operate the AOD with more than an octave of bandwidth with negligible spurious energy going to the harmonic beams and a total bandwidth broadening of over 70%.
Temporal and spatial shaping of laser beams is common in laser micromachining applications to improve quality and throughput. However, dynamic beam shaping (DBS) of ultrashort, high-power pulses at rates of hundreds of kHz has been challenging. Achieving this allows for full synchronization of the beam shape with high repetition rates, high-power lasers with zero delay time. Such speeds must manipulate the beam shape at a rate that matches the nanosecond to microsecond process dynamics present in laser ablation. In this work, we present a novel design capable of alternating spatial and temporal beam shapes at repetition rates up to 330 kHz for conventional spatial profiles and temporal shaping at nanosecond timescales. Our method utilizes a unique multi-aperture diffractive optical element combined with two acousto-optical deflectors. These high damage threshold elements allow the proposed method to be easily adapted for high power ultrashort lasers at various wavelengths. Moreover, due to the combination of the elements mentioned, no realignment or mechanical movements are required, allowing for high consistency of quality for high throughput applications.
A method is described where 3D electronic devices are fabricated using a hybrid printing approach which combines several steps: Top illumination stereolithography (SLA); Laser induced forward transfer (LIFT) printing of conductive materials; Placement of active and passive components and their electrical interconnection by a non-contact, metal LIFT process. By applying this approach, free-form 3D functional electronic structures could be manufactured by a single hybrid tool. The adhesion of LIFT printed metal droplets onto various organic substrates of interest for device fabrication was investigated. The results suggest two possible approaches for improved adhesion by either printing at elevated surface temperature or surface roughening by laser pre-treatment. The resulting track resistivities were found to be in the range of x5-10 higher than bulk copper resistivity. We present several exemplary printed devices with different complexities and functionalities as demonstrators of the proposed hybrid technology. 
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