Abstract
We have studied the transfer regimes and dynamics of polymer flyers from laser-induced backward transfer (LIBT) via time-resolved shadowgraphy. Imaging of the flyer ejection phase of LIBT of 3.8μm and 6.4μm thick SU-8 polymer films on germanium and silicon carrier substrates was performed over a time delay range of 1.4–16.4μs after arrival of the laser pulse. The experiments were carried out with 150fs, 800nm pulses spatially shaped using a digital micromirror device, and laser fluences of up to 3.5J/cm2 while images were recorded via a CCD camera and a spark discharge lamp. Velocities of flyers found in the range of 6–20m/s, and the intact and fragmented ejection regimes, were a function of donor thickness, carrier and laser fluence. The crater profile of the donor after transfer and the resulting flyer profile indicated different flyer ejection modes for Si carriers and high fluences. The results contribute to better understanding of the LIBT process, and help to determine experimental parameters for successful LIBT of intact deposits.
Highlights
Additive methods for the microfabrication of devices have recently gained interest over conventional techniques due to their versatility, simplicity and resulting high speed of fabrication [1,2,3].Among these, laser-based techniques are a promising way to enable device printing in a contactless fashion with demonstrated micronscale resolution
We have studied the transfer regimes and dynamics of polymer flyers from laser-induced backward transfer (LIBT) via time-resolved shadowgraphy
The comparison of a thin flyer from a Si carrier in Table 1 shows slightly higher velocities for a flyer ejected at 20% higher fluence but otherwise similar conditions for the mean velocity
Summary
Additive methods for the microfabrication of devices have recently gained interest over conventional techniques due to their versatility, simplicity and resulting high speed of fabrication [1,2,3].Among these, laser-based techniques are a promising way to enable device printing in a contactless fashion with demonstrated micronscale resolution. Additive methods for the microfabrication of devices have recently gained interest over conventional techniques due to their versatility, simplicity and resulting high speed of fabrication [1,2,3]. A unique advantage is that these methods allow the deposition of materials that have a specific structural role, and have electronic, photonic or even biomedical functionality. Laser-induced forward transfer (LIFT) has proven its capability to allow manufacturing of a wide range of materials, such as metals [4], ceramics, semiconductors, superconductors [5], 2D materials and structures for e.g. MEMS [6], waveguides [7], biomedical sensors [8] or thermoelectric generators [9]. During LIFT (e.g. with a transparent donor), Laboratory of Mechanical Automation and Mechatronics, Faculty of Engineering
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