New Photoimageable LTCC Technology for Making a Wide Range of Ceramic Architectures and Circuits

摘要

Low Temperature Cofired Ceramic (LTCC) materials have gained broad acceptance for high density and RF applications due to cost and performance advantages versus both conventional thick film and organic printed wiring board materials. As circuit complexity increases, it is difficult to achieve desired performance and cost using conventional mechanical methods of punching to form vias and other features. Vias or feature formation using numerically controlled punches requires a large investment with relatively low throughput for small vias and high via densities, on the other hand, gang punching entails high tooling costs and limited flexibility for design changes. Industry demands for high circuit density, faster time to market, and lower manufacturing cost have prompted development of a new Photoimageable Low Temperature Cofired Ceramic (PI-LTCC) tape technology. This new tape system can be used in electronic packaging and interconnect applications to achieve high circuit density, high productivity and low manufacturing cost, and with potential to do continuous reel-to-reel processing. In addition, the capability to form complex shapes and channels creates opportunities for innovation in areas outside current conventional electronic packaging. The new PI-LTCC materials system has the same fired film chemistry and properties of DuPont 951 Green Tape~(TM), the industry standard for LTCC systems, facilitating easy adoption in existing applications. This paper describes new PI-LTCC technology and processes developed to facilitate formation of high resolution, fine pitch via structures, as well as complex 3D features and architectures. The new tape composition is capable of forming features as small as 50 microns. Potential applications in thermal management and sensing are also described. UV light is used to image PI-LTCC material and development is accomplished with 1% sodium carbonate solution. The photo process lends itself to rapid design changes and simultaneously making large and small features.