Fig xA XRD patterns of the

4. Discussion
Incorporation of PMMA microspheres into tape casting slurries proved to be a feasible method of adding porosity to LTCC and thus decreasing the permittivity even though the sintering mechanisms of Dupont 951 and Ferro A6M LTCC systems are totally different. Further optimization of the slurry composition and sample preparation process should have a positive influence on key properties such as green state performance, lamination, sintering shrinkage and final density.
Even though further research is required to improve the mechanical properties of the tapes and their lamination, the dielectric measurements have proven the concept of this BQ-3020 paper. Addition of PMMA microspheres has successfully lowered the dielectric permittivity of every sample. Furthermore, the value of the dielectric permittivity can be easily adjusted in some range, by changing the amount of added PMMA micropsheres. Moreover, the addition of microspheres had very little or no impact on the dielectric losses as can be seen from Fig. 2 and Fig. 3. The lowest measured value of relative permittivity in veins paper – 3.71 achieved by the Ferro based sample with 30 wt% of PMMA looks promising when compared to over 300 LTCCs presented in [2]. In particular the lowest permittivity published in scientific journals according to [2] is 4.7 [3] which is 22% higher than reached here.