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Proceedings Paper

Laser forward transfer of solder paste for microelectronics fabrication
Author(s): Scott A. Mathews; Nicholas A. Charipar; Ray C.Y. Auyeung; Heungsoo Kim; Alberto Piqué
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Paper Abstract

The progressive miniaturization of electronic devices requires an ever-increasing density of interconnects attached via solder joints. As a consequence, the overall size and spacing (or pitch) of these solder joint interconnects keeps shrinking. When the pitch between interconnects decreases below 200 μm, current technologies, such as stencil printing, find themselves reaching their resolution limit. Laser direct-write (LDW) techniques based on laser-induced forward transfer (LIFT) of functional materials offer unique advantages and capabilities for the printing of solder pastes. At NRL, we have demonstrated the successful transfer, patterning, and subsequent reflow of commercial Pb-free solder pastes using LIFT. Transfers were achieved both with the donor substrate in contact with the receiving substrate and across a 25 μm gap, such that the donor substrate does not make contact with the receiving substrate. We demonstrate the transfer of solder paste features down to 25 μm in diameter and as large as a few hundred microns, although neither represents the ultimate limit of the LIFT process in terms of spatial dimensions. Solder paste was transferred onto circular copper pads as small as 30 μm and subsequently reflowed, in order to demonstrate that the solder and flux were not adversely affected by the LIFT process.

Paper Details

Date Published: 12 March 2015
PDF: 9 pages
Proc. SPIE 9351, Laser-based Micro- and Nanoprocessing IX, 93510Y (12 March 2015); doi: 10.1117/12.2080410
Show Author Affiliations
Scott A. Mathews, Naval Research Lab. (United States)
Nicholas A. Charipar, Naval Research Lab. (United States)
Ray C.Y. Auyeung, Naval Research Lab. (United States)
Heungsoo Kim, Naval Research Lab. (United States)
Alberto Piqué, Naval Research Lab. (United States)

Published in SPIE Proceedings Vol. 9351:
Laser-based Micro- and Nanoprocessing IX
Udo Klotzbach; Kunihiko Washio; Craig B. Arnold, Editor(s)

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