Low Temperature Cofired Ceramics (LTCC) are widely used for robust, high density packaging. While it is common to create smaller LTCC boards for development parts, usually from 2"×2" to 5"×5", using smaller panel sizes in production can be costly due to wasted area on the outside of the panel. To save money, LTCC manufacturers may create larger panels and/or use zero-shrink LTCC materials. [1] Zero-shrink LTCC allows for higher part density per panel by inhibiting shrinkage in the x-y direction to under 0.25 percent [2, 3]; all shrinkage occurs in the z direction. Another advantage of zero-shrink LTCC is better alignment during firing of larger panels because the panel stays rigid. There are three techniques for creating zero-shrink LTCC: Pressure-Assisted Sintering, Pressureless-Assisted Sintering, and Self-^sConstrained Sintering. The technique discussed in this paper is Pressureless-Assisted Sintering (PLAS). In this method, a release tape is laminated to the top and bottom of the green substrate. The release tape constrains the LTCC during sintering, but does not sinter. After firing, the body consists of the LTCC substrate and the baked out release tape, which is similar to a compressed powder coating. PLAS LTCC processing contains an extra process step, release tape removal, but is attractive to LTCC manufacturers because some release tape materials are developed to be used with already-existing LTCC systems. For example, DuPont 951RT (release tape) can be used with the DuPont 951 system. Typical release tape removal methods include scrubbing with a steel wool-type sponge and bead/sand blasting. While both methods are effective at removing the baked out tape, they are abrasive and difficult to control. Another method for removing release tape has been discovered using industrial detergents in an ultrasonic bath. This method does not harm the LTCC substrate integrity or the surface metallization.
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