Preparation and characterization of low temperature curing conductive silver paste for screen printing

A monopropellant micropropulsion device is being developed in low-temperature cofired ceramics (LTCC). The device uses catalytic decomposition of hydrogen peroxide as a propellant: hence catalytic channels are embedded internally in these devices. Consistent construction of these channels depends on a wide range of variables both in the design and fabrication of the channel structures. The primary focus of this paper is the characterization of final channel geometry when silver paste is applied to the upper and lower surfaces of an embedded single layer channel. Application of silver paste to the upper and lower channel surfaces has been shown to alter the final shape of the channels within the test structure. Upper and lower surface deflection into the channel area is discussed and characterization of this phenomena is illustrated as a function of channel width. A design of experiment (DOE) method is used to explore how process parameters affect the channel geometry/integrity. Construction of the test structures includes the use of pressure sensitive adhesives and a sacrificial material to maintain the overall channel geometry/integrity. Lamination and firing profiles are modified in order to enhance this construction methodology. Techniques used to produce and characterize these channels are discussed as well as the methods used to maintain channel geometry/integrity.

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Characterization of the Fabrication Process of Rolled LTCC Structures

Additional Conferences (Device Packaging HiTEC HiTEN & CICMT) ◽

10.4071/cicmt-2012-tp63 ◽

2012 ◽

Vol 2012 (CICMT) ◽

pp. 000251-000257

Author(s):

Kelci Parrish ◽

Jesse Taff ◽

Mallory Yates ◽

Derek Reis ◽

Donald Plumlee

Keyword(s):

Low Temperature ◽

Inductively Coupled Plasma ◽

Argon Plasma ◽

Fabrication Process ◽

Silver Paste ◽

Plasma Antenna ◽

Inductively Coupled ◽

Single Structure ◽

Tube Structure

This work focuses on the fabrication and assembly of cylindrical plasma containment tubes using DuPont's 951 Low Temperature Co-fired Ceramics (LTCC) for use in miniature electrostatic thrusters. The use of LTCC allows for robustness post-firing yet flexibility in the “green” un-fired state. Some of the main advantages of this flexibility include the ability to stack or roll the LTCC sheets into various shapes as well as incorporating embedded electrical interconnections using silver paste on the rolled layers. The tube is used to contain argon plasma, which is generated by a spiral Inductively Coupled Plasma antenna and is also fabricated in LTCC. The tube also interfaces with two electrically biased grids on the opposite end, which accelerate the plasma out of the tube. These interfaces are highly dependent on the dimensions and tolerances of the containment tube. The development of the fabrication process will be presented for the incorporation of the tubes onto the base as a single structure. This includes constructing the antenna base, shaping the “rolled” LTCC containment tube using a jig and isostatic press, and integrating the tube and antenna base during the firing. Following the fabrication, measurements will be taken to determine the tube circularity and the hermeticity of the seal at the interface between the tube and the antenna base. The results will be presented and characterized to evaluate the effectiveness of the structure as well as the documentation of the development of a rolled LTCC tube structure integrated with a planar LTCC antenna base.

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