A novel microscale selective laser sintering (μ-SLS) process for the fabrication of microelectronic parts

Abstract

One of the biggest challenges in microscale additive manufacturing is the production of three-dimensional, microscale metal parts with a high enough throughput to be relevant for commercial applications. This paper presents a new microscale additive manufacturing process called microscale selective laser sintering (μ-SLS) that can produce true 3D metal parts with sub-5 μm resolution and a throughput of greater than 60 mm 3 /hour. In μ-SLS, a layer of metal nanoparticle ink is first coated onto a substrate using a slot die coating system. The ink is then dried to produce a uniform nanoparticle layer. Next, the substrate is precisely positioned under an optical subsystem using a set of coarse and fine nanopositioning stages. In the optical subsystem, laser light that has been patterned using a digital micromirror array is used to heat and sinter the nanoparticles into the desired patterns. This set of steps is then repeated to build up each layer of the 3D part in the μ-SLS system. Overall, this new technology offers the potential to overcome many of the current limitations in microscale additive manufacturing of metals and become an important process in microelectronics packaging applications.

Additive Manufacturable Materials for Electrochemical Biosensor Electrodes

“…[ 300 ] The resolution of SLS/SLM is ≈10–100 µm, depending on factors such as laser spot size, writing speed, and particle size. [ 301,302 ]…”

Powder-Based 3D Printing for the Fabrication of Device with Micro and Mesoscale Features

“…As reported, SLS 3D-printing process can produce a typical feature size around 200 μm [ 125 ]. SLS 3D-printing process can produce typical feature size around 40–100 μm [ 50 , 58 , 126 ]. The SLS 3D-printing process is suitable for processing a range of materials, such as nylon, polycarbonate, composite of nylon-glass, ceramics, polymer-metal powders, hydroxyapatite, etc.…”

“…The powder-based 3D printing avoids shortcomings of SLA and other 3D-printing techniques based on photopolymerization, but it suffers from limited resolution and undesired optical properties (e.g., non-transparent). Fortunately, a new-generation of powder-based 3D-printer attempts to address some of these challenges [ 48 , 51 , 58 , 59 , 60 , 123 , 239 ]. Once these barriers are lifted, powder-based 3D printing will be more widely applicable.…”

“…The conventional micromachining techniques are unable to achieve true 3D structures and face challenges in manufacturing complex shapes [ 46 , 47 ]. Significant effort has been put into developing micro 3D printing processes based on stereolithography (SLA), material/binder jetting, micro selective laser melting/sintering processes and micro cladding [ 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ]. Although micro 3D printing can print true 3D microfeatures, its throughput is too low for industrial scale manufacturing [ 48 , 49 , 50 , 51 , 52 , 53 ] and most of these techniques are still under development phase.…”

Single shot, large area metal sintering with micrometer level resolution

“…The final part goes through a washing step to get rid of the un-sintered portions and then post heat treatment is done to improve the sintering quality of the part. An overview of the system with process details and scheme is part of a working study by the authors [32].…”