Device Packaging 2019

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Thermal and electrical impact of printed metals for electrical interconnect
Keywords: Printed electronics, Silver, Joule heating
Printed additive technologies applied to electronics have the potential to reduce design cycle time, allow greater customization, lower the cost of small production runs, and increase compatibility with non-planar substrates. In nearly every scenario, however, printed conductive traces have higher electrical resistance than their bulk counterparts which negatively impacts power design, reliability, RF performance, and joule heating. This is often mitigated by using silver (Ag) inks that have low intrinsic resistivity and, just as importantly, “sinter” at low temperatures due to high surface diffusivity. This desirable quality allows for the integration of the printed silver ink with COTS parts which cannot be exposed to temperatures above 200 °C. However, the same high surface diffusivity causes the conductive lines to break at moderate currents when electromigration occurs and is exacerbated by localized joule heating. We propose strategies through alternate metallurgies and, in some cases, metal formulations that induce reactive sintering to both augment electrical conductivity and inhibit or eliminate failure due to electromigration. We present the case study of a quadcopter drone that requires high current power delivery in a miniaturized and thermally demanding form factor. Thermal measurements and simulations of self- heating on test structures help identify root cause of failures between electromigration and simple thermal fusing. Finally, we present design strategies such as nominal conductor thickness increases to further mitigate the degradation in resistivity and take advantage of the conformal, adaptive technology that printed manufacturing offers.
Brian R. Smith, Principal Member of the Technical Staff
Cambridge, MA

  • Amkor
  • ASE
  • Canon
  • Corning
  • EMD Performance Materials
  • Honeywell
  • Indium
  • Kester
  • Kyocera America
  • Master Bond
  • Micro Systems Technologies
  • MRSI
  • Palomar
  • Promex
  • Qualcomm
  • Quik-Pak
  • Raytheon
  • Specialty Coating Systems
  • Technic