Direct Write Electronics – Thick Films on LTCC

Abstract

For low volume, high value microelectronic applications reducing cost and time to initial production parts in Low Temperature Cofired Ceramics (LTCC) play a big part in customer satisfaction. Using Direct Write Electronics (DWE) for conductor printing and other structures has the potential to reduce time to production through elimination of intermediate tooling and to reduce waste by applying expensive materials only where they are needed. Additional benefits may be realized by using DWE: wire bonds may be replaced by dispensed conductors; individual layers and parts may be uniquely labeled at the time of printing to improve traceability of product throughout the line and reducing manufacturing errors. This paper investigates using engineered fluid dispensing to print interior and exterior conductors on a demonstration Multi-Chip Module (MCM). Industry standard materials and processes are used to form individual layers of unfired LTCC tape, as well as the forming and filling of interlayer connecting vias with conductive thick film paste. Conductor patterns on each layer are created by dispensing modified Au conductor paste with a commercial three-axis machine with a fine-tipped dispensing pump. Standard processes for collation, lamination, and sintering were followed by aerosol jet printing of Ag ink with a commercial print head mounted on a custom, 6-axis positioning gantry to form wire bond replacements, part identification and individualized markings. Resultant parts are tested for electrical functionality and cross sections are compared to in-progress build photos and line measurements to study the effect of the new printing method vs. structures produced with standard conductor printing processes.