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PYROLYZABLE BACKING TAPE FOR SINGULATION OF CERAMIC COMPONENTS

IP.com Disclosure Number: IPCOM000004675D
Original Publication Date: 2001-Mar-30
Included in the Prior Art Database: 2001-Mar-30
Document File: 2 page(s) / 8K

Publishing Venue

Motorola

Related People

Kristen Law: AUTHOR

Abstract

PYROLYZABLE BACKING TAPE FOR SINGULATION OF CERAMIC COMPONENTS

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PYROLYZABLE BACKING TAPE FOR SINGULATION OF CERAMIC COMPONENTS

by Kristen Law

The use of a tape backing material during the dicing process of low temperature cofired ceramic components (LTCC) serves to prevent singulated components from adhering to the dicing blade during blade upstroke at the completion of cut and to maintain part orientation after singulation. Tape stabilization is required for hot knife singulation of all green ceramic parts with dimensions of less than 5mm and improves singulation capability and repeatability for larger parts.

Current convention requires the removal of singulated parts from the backing tape after the cutting process has been completed. Removal increases cycle time and can lead to deformation of the pliable green ceramic components due to the stress required to remove the backing tape.

The proper use of backing tape requires that the dicing blade be set at a level that just cuts through the component but does not score or cut the tape. In the conventional process, components are removed from the backing material after singulation and prior to the next processing step.

Typically a low tack tape is utilized for singulation and components are either removed manually or an automated picking tool is used. This removal step entails added cost and time.

To eliminate the tape removal step, a tape material can be used that has a pyrolysis profile which matches that of the ceramic firing profile and leaves minimal ash. Firing profile match is critical for minimizing warpage due to material flow mismatch as a function of temperature. Minimal residual ash content is required to maintain solderability of the component to the circuit board.

A variety of tape materials were evaluated for process suitability including polyethylene, cellulose, and polyester based tapes. Optimal results in terms of residual ash and firing profile were obtained with polyester tape containing acrylate adhesive. Figure 1 displays the thermal gravimetric analysis profile of the tape in blue with the firing profile of the ceramic superimposed in red.

The binder burnout profile of the ceramic is a 30-minute hold at 450°C. This temperature corresponds closely with the midpoint of the tape decomposition temperature at 425°C. The thirty minute hold is sufficient to decompose approximately 95% of the tape.

The remaining tape content volatilizes during the sintering ramp to 865°C to leave less than 0.5 weight ash.

The tape must be applied to the ceramic substrate with minimal entrapment of air. Air pockets will increase the effective local thickness of the ceramic leading to incompletely cut regions. The use of a vacuum stage with the pyrolyzable tape effectively minimized air entrapment. The process requires that the tape be applied to the stage with the tacky side facing upward. Vacuum is released as the tape is pulled across the stage and engaged when the tape completely covers the stage.

The unsingulated ceramic is placed on the tape with bare ceramic facing the...