Automated Fabrication of Ceramic Electronic Packages by Stereo-Photolithography
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173 Mat. Res. Soc. Symp. Proc. Vol. 625 © 2000 Materials Research Society Downloaded from https:/www.cambridge.org/core. The Librarian-Seeley Historical Library, on 31 Mar 2017 at 07:58:47, subject to the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms. https://doi.org/10.1557/PROC-625-173
advanced photolithography systems. The general process utilizes photocureable resins filled with sinterable ceramic (insulators, capacitors, resistors) or metal (conductors) powders. The automated build process will provide deposition of thin layers of the materials, a means for photopatteming each layer and a means for removing unexposed material from the layer. Ultimately, the process will be capable of depositing an insulator, a conductor, capacitor and resistor materials. For the initial purpose of demonstrating feasibility, a two material system has been studied consisting of a low temperature co-fire ceramic insulator and a silver conductor. EXPERIMENT Several approaches to photopatterning conductor traces on the surface or embedded in a ceramic substrate can be used. The approach presented here is shown in Figure 1. Step a) shows the deposition head applying a layer of insulator resin on the build surface. The desired areas are selectively exposed through a photomask by a UV flood lamp and cured. The build platform is lowered by one layer thickness relative to the tip of the deposition head. Multiple insulator layers are deposited as desired. Step b) shows deposition of a conductor filled photoresin on top of the insulator layers. The conductor resin is selectively exposed. Step c) shows removal of the uncured conductor resin using a "developer head", leaving only the exposed regions (conductor lines and vias) attached to the previous insulator layer. Without lowering the build platform, a layer of insulator resin is applied such that it surrounds the conductor patterns and is exposed (Step d). Repetition of these basic steps allows the layer-by-layer fabrication of green state electronic packages with embedded conductors. Use of additional deposition heads will enable fabrication of packages with embedded passive elements (capacitors and resistors). A)
B) Ialumina deposition head
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Cleaning Head
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Figure 1. Process flow of a photopatterning approach for multilayer ceramic packages. For these feasibility studies, a manual system was set-up using an Oriel photolithography machine, which provided an 8-inch diameter of collimated, uniform intensity UV/Vis light (1,000 Hg/Xe bulb). The mask holder of this system was modified by adding a blade supported on bearing rails to allow application of thin layers onto the build platform. Removal of uncured
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