Improved compaction in multilayer capacitor fabrication

The most common defects found in multi-layer ceramic capacitors are derived from residual porosity formed when solvents and binders are released from a ceramic green body. Without a well-controlled compaction technique, defec ts between sheets in the stacked body are often present, leading to laminat ion problems. This paper suggests alternative approaches, using compaction applied before and/or after the process of binder burnout with the intentio n of reducing the number of stacking-generated defects and the volume of vo ids formed after binder burn-out. Barium titanate tapes and stacked multila yer electroded discs have been investigated and characterised by microstruc tural examination and density measurement. The resulting properties are des cribed, and the behaviour of the multi-layers discussed in terms of the Mic rostructure and processing procedures. It is shown that the porosity conten t of sintered samples compacted at 300 MPa is approximately half that of sa mples compacted at 30 MPa when both are sintered at 1300 degrees C for 2 h. A further improvement of densification cart be achieved by a postcompactio n treatment after binder burn out. (C) 1999 Elsevier Science Limited. All r ights reserved.