Method of fabricating electromagnetic bandgap (EBG) structures for microwave/millimeterwave applications using laser processing of unfired low temperature co-fired ceramic (LTCC) tape
View Patent ↗Substrates and methods to fabricate and use millimeter wave Sievenpiper EBG structures such that the conductive portions are internal to an LTCC package.
1. An electromagnetic bandgap (EBG) structure comprising:
a. an LTCC package comprised of (i) an array of conductive patches on LTCC tape layers separated by gaps, wherein some of the gap dimensions are between 1 and 3 mils; (ii) an array of conductive vias in one or more tape layers connected to the array of conductive patches; and
b. an RF backplane connected to the array of vias, wherein the array of conductive patches are created by block printing an unfired conductive paste on a plurality of unfired tape layers and laser ablating gaps between adjacent patches prior to firing the LTCC package.
2. The structure of claim 1 , wherein the gap dimension is adjusted to set a bandgap cutoff frequency to a desired value.
3. The structure of claim 1 , wherein the structure transmits a frequency about 40 GHz.
4. A method of fabricating an electromagnetic bandgap (EBG) structure comprising:
forming an LTCC package comprised of a plurality of tape layers,
forming an array of conductive patches on at least one of the tape layers by
block printing a conductive paste, and
laser ablating gaps between adjacent patches which gaps have a dimension of between 1 and 3 mils.
5. The method of claim 4 , wherein the process of laser ablation is performed on an unfired green tape prior to firing the LTCC package.
6. The method of claim 4 , wherein the array of conductive patches is internal to the LTCC package.
7. The method of claim 4 , wherein the thickness of the conductive paste is between 7 and 20 microns.
8. The method of claim 4 , wherein the gap dimension is adjusted to set a bandgap cutoff frequency to a desired value.
9. The method of claim 4 , wherein the EBG structure comprises an array of conductive vias in one or more tape layers wherein the vias are connected to the array of conductive patches.
10. The method of claim 9 , wherein the EBG structure comprises an RF backplane wherein the array of vias is connected to the RF backplane.
11. The method of claim 10 , wherein the EBG structure is a Sievenpiper EBG structure.
12. An EBG structure formed by the method of claim 11 .
13. A method to transmit millimeterwave frequencies while suppressing the propagation of parasitic surface waves comprising:
a. preparing a electromagnetic badgap (EBG) structure comprising (i) an LTCC package comprised of (A) an array of internal conductive patches separated by gaps of between 1 and 3 mils; (B) an array of conductive vias in one or more tape layers connected to the array of conductive patches; and (ii) an RF backplane connected to the array of vias, wherein the array of conductive patches are created by block printing an unfired conductive paste on a plurality of unfired tape layers and laser ablating gaps between adjacent patches prior to firing;
b. transmitting in circuits which operate above a frequency of 40 GHz.