Substrate-integrated device and method for making the same

A substrate-integrated device includes a substrate layer with a first dielectric constant and one or more dielectric vias, the one or more dielectric vias each includes a via-hole extending through the substrate layer, and a dielectric material with a second dielectric constant contained within the via-hole. The second dielectric constant is larger than, preferably at least two times, the first dielectric constant.

TECHNICAL FIELD

The invention relates to a substrate-integrated device and a method for making a substrate-integrated device.

BACKGROUND

A via is an electrical connection between different layers in an electronic circuit. Conventional vias are metallic vias in the form of a “metallized” hole (i.e., a hole coated with a metallic material) in a substrate.

Metallic vias are commonly used in RF (such as PCB applications) and IC technologies. In RF technology, metallic via-holes are used in place of solid metallic walls. In IC technology, metallic vias are used to electrically connect different layers of substrates with each other. Problematically, however, these metallic vias may suffer from high loss in some applications, such as applications as microwave frequencies. Also, the process for “metallizing” the holes to produce the vias can be time-consuming and costly.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the invention, there is provided a substrate-integrated device, having: a substrate layer with a first dielectric constant and one or more dielectric vias. The one or more dielectric vias each having a via-hole extending through the substrate layer, and a dielectric material with a second dielectric constant contained within the via-hole. The second dielectric constant (relative permittivity) is larger than the first dielectric constant. Preferably, the second dielectric constant is at least two times, at least three times, at least four times, at least five times, or at least ten times of the first dielectric constant.

In one embodiment of the first aspect, the via-hole is filled substantially completely with the dielectric material.

In one embodiment of the first aspect, the first electric constant is at least 2 and the second dielectric constant is at least 4. Preferably, the second dielectric constant is at least 10, at least 15, or at least 20.

In one embodiment of the first aspect, the one or more dielectric vias includes a plurality of dielectric vias. The plurality of dielectric vias may be arranged regularly or randomly. The plurality of dielectric vias may be spaced apart evenly. In one example, the plurality of dielectric vias includes dielectric vias arranged in at least two parallel rows, each of the two parallel rows having two or more dielectric vias. One or more dielectric vias may further be arranged between the two parallel rows. In one example, two adjacent parallel rows of dielectric vias define, between the two rows, a wave guiding channel.

In one embodiment of the first aspect, the dielectric material includes perovskite oxide. The perovskite oxide may include one or more of: Barium Titanate, Barium Strontium Titanate, Lead ZirconateTitanate, and Lead Lanthanum ZirconateTitanate.

In one embodiment of the first aspect, the dielectric material is in the form of a paste. In one example, the paste includes perovskite oxide particles. The perovskite oxide particles may include one or more of: Barium Titanate particles, Barium Strontium Titanate particles, Lead ZirconateTitanate particles, and Lead Lanthanum ZirconateTitanate particles. The perovskite oxide particles may be sized between 30 nm to 2000 nm, or they may have an average size between 30 nm to 2000 nm.

In one embodiment of the first aspect, the substrate-integrated device further includes a first material layer arranged on one side of the substrate layer. The first material layer may include a prepreg, a metallic layer, or a dielectric layer with the dielectric material.

In one embodiment of the first aspect, the substrate-integrated device further includes a second material layer arranged on the other side of the substrate layer. The second material layer may include a prepreg, a metallic layer, or a dielectric layer with the dielectric material.

In one embodiment of the first aspect, the substrate-integrated device is a microwave device.

In one embodiment of the first aspect, the substrate-integrated device is a printed circuit board.

In one embodiment of the first aspect, the substrate-integrated device is a substrate-integrated waveguide.

In one embodiment of the first aspect, the substrate-integrated device is a substrate-integrated dielectric resonator.

In one embodiment of the first aspect, the substrate-integrated dielectric resonator is part of a substrate-integrated dielectric resonator antenna.

In one embodiment of the first aspect, the substrate-integrated dielectric resonator is part of a substrate-integrated dielectric resonator filter.

In one embodiment of the first aspect, the substrate-integrated device is arranged to operate at radio frequency range.

In accordance with a second aspect of the invention, there is provided a method for making a substrate-integrated device, comprising: arranging, in one or more via-holes of a substrate layer with a first dielectric constant, a dielectric material with a second dielectric constant, thereby forming one or more dielectric vias. The one or more dielectric vias each having a via-hole formed in the substrate layer, and a dielectric material with a second dielectric constant contained within the via-hole. The second dielectric constant is larger than the first dielectric constant. Preferably, the second dielectric constant is at least two times, at least three times, at least four times, at least five times, or at least ten times of the first dielectric constant.

In one embodiment of the second aspect, arranging the dielectric material in the one or more via-holes includes: filling the one or more via-holes substantially completely with the dielectric material.

In one embodiment of the second aspect, the first dielectric constant is at least 2 and the second dielectric constant is at least 4. Preferably, the second dielectric constant is at least 10, at least 15, or at least 20.

In one embodiment of the second aspect, the dielectric material comprises perovskite oxide. The perovskite oxide may include one or more of: Barium Titanate, Barium Strontium Titanate, Lead ZirconateTitanate, and Lead Lanthanum ZirconateTitanate.

In one embodiment of the second aspect, arranging the dielectric material in the one or more via-holes includes: arranging a paste including the dielectric material in the one or more via-holes.

In one embodiment of the second aspect, the paste comprises pre-sintered perovskite oxide particles and a solvent. The pre-sintered perovskite oxide particles may include one or more of: Barium Titanate particles, Barium Strontium Titanate particles, Lead ZirconateTitanate particles, and Lead Lanthanum ZirconateTitanate particles. The solvent may include one or more of: Xylene, Toluene, and Tetrahydrofuran. The perovskite oxide particles may be sized between 30 nm to 2000 nm, or they may have an average size between 30 nm to 2000 nm.

In one embodiment of the second aspect, arranging the dielectric material in the one or more via-holes further includes: heating the paste to evaporate the solvent and attach the dielectric material to the substrate.

In one embodiment of the second aspect, arranging the dielectric material in the one or more via-holes further includes: enclosing the one or more via-holes to retain the paste in the one or more via-holes.

In one embodiment of the second aspect, enclosing the one or more via-holes includes: arranging a first material layer on one side of the substrate and at a first end of the one or more via-holes and arranging a second material layer on another side of the substrate and at a second end of the one or more via-holes to enclose the one or more via-holes. The first material layer and the second material layer each includes a prepreg, a metallic layer, or a dielectric layer with the dielectric material.

In accordance with a third aspect of the invention, there is provided a substrate-integrated device made using the method of the second aspect.

In accordance with a fourth aspect of the invention, there is provided a structure for confining electromagnetic energy, having: a substrate layer with a first dielectric constant and one or more dielectric vias. The one or more dielectric vias each having a via-hole extending through the substrate layer, and a dielectric material with a second dielectric constant contained within the via-hole. The second dielectric constant (relative permittivity) is larger than the first dielectric constant. Preferably, the second dielectric constant is at least two times, at least three times, at least four times, at least five times, or at least ten times of the first dielectric constant.

In one embodiment of the fourth aspect, the via-hole is filled substantially completely with the dielectric material.

In one embodiment of the fourth aspect, the first dielectric constant is at least 2 and the second dielectric constant is at least 4. Preferably, the second dielectric constant is at least 10, at least 15, or at least 20.

In one embodiment of the fourth aspect, the one or more dielectric vias includes a plurality of dielectric vias. The plurality of dielectric vias may be arranged regularly or randomly. The plurality of dielectric vias may be spaced apart evenly. In one example, the plurality of dielectric vias includes dielectric vias arranged in at least two parallel rows, each of the two parallel rows having two or more dielectric vias. One or more dielectric vias may further be arranged between the two parallel rows. In one example, two adjacent parallel rows of dielectric vias define, between the two rows, a wave guiding channel.

In one embodiment of the fourth aspect, the dielectric material includes perovskite oxide. The perovskite oxide may include one or more of: Barium Titanate, Barium Strontium Titanate, Lead ZirconateTitanate, and Lead Lanthanum ZirconateTitanate.

In one embodiment of the fourth aspect, the dielectric material is in the form of a paste. In one example, the paste includes perovskite oxide particles. The perovskite oxide particles may include one or more of: Barium Titanate particles, Barium Strontium Titanate particles, Lead ZirconateTitanate particles, and Lead Lanthanum ZirconateTitanate particles. The perovskite oxide particles may be sized between 30 nm to 2000 nm, or they may have an average size between 30 nm to 2000 nm.

In one embodiment of the fourth aspect, the structure further includes a first material layer arranged on one side of the substrate layer. The first material layer may include a prepreg, a metallic layer, or a dielectric layer with the dielectric material.

In one embodiment of the fourth aspect, the structure further includes a second material layer arranged on the other side of the substrate layer. The second material layer may include a prepreg, a metallic layer, or a dielectric layer with the dielectric material.

In accordance with a fifth aspect of the invention, there is provided a microwave device including the structure of the fourth aspect.

In accordance with a sixth aspect of the invention, there is provided a substrate-integrated waveguide including the structure of the fourth aspect.

In accordance with a seventh aspect of the invention, there is provided a substrate-integrated dielectric resonator including the structure of the fourth aspect.

In accordance with a eighth aspect of the invention, there is provided a substrate-integrated dielectric resonator antenna including the structure of the fourth aspect.

In accordance with a eighth aspect of the invention, there is provided a substrate-integrated dielectric resonator filter including the structure of the fourth aspect.

In accordance with a ninth aspect of the invention, there is provided a substrate-integrated dielectric resonator antenna, including a first substrate layer with a first dielectric constant; one or more dielectric vias each having a via-hole formed in the substrate layer, and a dielectric material with a second dielectric constant contained within the via-hole, the second dielectric constant is larger than (e.g., at least two times) the first dielectric constant; a ground plane arranged on one side of the first substrate layer; a second substrate layer attached to the first substrate layer via the ground plane; and a microstrip line attached to the second substrate layer on a side opposite to the ground plane. Preferably, in plan view, the microstrip at least partly overlaps with the one or more dielectric vias and with a slot formed in the ground plane.

In accordance with a tenth aspect of the invention, there is provided a printed circuit board including the structure of the fourth aspect.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1A and 1Bshow a structure too with dielectric vias104in plan view. The structure too can be used to confine or guide electromagnetic energy. As shown inFIGS. 1A and 1B, the structure too includes a substrate layer102with a first dielectric constant. The substrate layer102may be formed of a substrate material used in printed circuit boards, and the first dielectric constant may be around 2 to around 4. In this example, sixteen dielectric vias104are arranged in the substrate layer102, in a 4×4 array. Each of the dielectric vias104includes a via-hole of circular cross section and diameter d extending through the substrate layer102and a dielectric material106filled inside the via-hole. The dielectric material106filling the via-hole has a dielectric constant (relative permittivity) that is at least two times the dielectric constant of the substrate layer102. Preferably, the first dielectric constant is at least 2 and the second dielectric constant is at least 4. In some example, the second dielectric constant can be at least to, at least 15, or at least 20.

In this embodiment, the dielectric material106includes perovskite oxide. Example of perovskite oxide includes Barium Titanate, Barium Strontium Titanate, Lead ZirconateTitanate, and Lead Lanthanum ZirconateTitanate. The dielectric material106may be in the form of a paste retained in the via-hole, or may be in the form of a solid solidified from an initial paste form. In one example, the paste includes perovskite oxide particles. Example of perovskite oxide particles include one or more of: Barium Titanate particles, Barium Strontium Titanate particles, Lead ZirconateTitanate particles, and Lead Lanthanum ZirconateTitanate particles. The perovskite oxide particles are sized in one dimension between 30 nm to 2000 nm. On average, the perovskite oxide particles can be sized in one dimension between 30 nm to 2000 nm. In the example that the dielectric material106is a paste, the structure too may further include two material layers, one on each side of the substrate, to enclose the via-holes hence retain the dielectric materials106in the via-holes. These two material layers may be a prepreg, a metallic layer, or a dielectric layer with the dielectric material same as that filled in the via-holes.

In the structure100, the dielectric vias104act as electric walls that provide a highly reflective boundary for confining or directing electromagnetic energy impinging on the walls. The structure100has a unit cell size of S×S.

The structure100inFIG. 1can be incorporated or can form a substrate-integrated device. Examples of the substrate-integrated device include: microwave device, printed circuit board, substrate-integrated waveguide, substrate-integrated dielectric resonator (which may be part of a substrate-integrated dielectric resonator antenna or filter). The substrate-integrated device is preferably arranged to operate at radio frequency or microwave range.

FIG. 2shows a method200for making the structure ofFIG. 1in one embodiment of the invention. The method200begins in step202, in which one or more via-holes106are arranged in the substrate layer102with the first dielectric constant. The via-holes may be arranged in the substrate layer by cutting, drilling, or the like. Then the method proceeds to step204, in which the dielectric material106with the second dielectric constant is arranged in the via-holes, to form the structure100. Step204may involve coating the via-hole with the dielectric material106. Alternatively, step204may involve filling the via-hole partly or completely with the dielectric material106. In one embodiment, step204includes arranging a paste with the dielectric material106and optionally a solvent in the via-holes. The paste may include pre-sintered perovskite oxide particles and a solvent. The pre-sintered perovskite oxide particles may include one or more of: Barium Titanate particles, Barium Strontium Titanate particles, Lead ZirconateTitanate particles, and Lead Lanthanum ZirconateTitanate particles; while the solvent may include one or more of: Xylene, Toluene, and Tetrahydrofuran.

Various methods can be used to attach or otherwise fix the dielectric material106to the substrate102. In one example, the paste may be heated to evaporate the solvent and solidify the dielectric material106so as to attach the dielectric material106to the substrate102. In another example, the paste may be enclosed in the via-holes by two material layers one on each side of the substrate (and each end of the via-hole). The two material layers may be a prepreg, a metallic layer, or a dielectric layer with the dielectric material106.

FIG. 3shows a substrate-integrated waveguide (SIW)300in one embodiment of the invention. The waveguide300has a similar basic structure as the structure100ofFIG. 1. InFIG. 3, the waveguide includes an upper metallic layer (very thin)301, a middle substrate layer302, and a lower metallic layer (very thin)303. Dielectric vias304of circular cross sectional and diameter d are arranged in the middle substrate layer302. In this embodiment, the dielectric vias304are arranged in two parallel rows. The dielectric vias304in the same row are spaced apart generally equally, with a separation (pitch, distance between cross sectional centers of adjacent vias in the same row) S. The two rows are separate by a separation (distance between cross sectional centers of corresponding vias) W. The space between the two parallel rows of the dielectric vias304defines a wave guiding channel306. In some embodiments, further dielectric vias (not shown) can be arranged between the two rows to provide filtering function.

FIGS. 4A and 4Bshow a substrate-integrated dielectric resonator antenna400in one embodiment of the invention. The dielectric resonator antenna400has a similar basic structure as the structure100ofFIG. 1. As shown inFIGS. 4A and 4B, the dielectric resonator antenna400includes a first upper substrate layer402with a first dielectric constant. An array of dielectric vias404is arranged in the first upper substrate layer402. The array of dielectric vias404resembles the shape of a dielectric resonator. Each dielectric via404includes a via-hole formed in the substrate layer402and a dielectric material406filled in the via-hole. The dielectric constant of the dielectric material406is at least two times the dielectric constant of the substrate402. The dielectric resonator antenna400also has a ground plane405arranged below the first substrate layer402. A second substrate layer407containing a feeding mechanism is attached to the first substrate layer402via the ground plane405. The feeding mechanism includes a slot (seeFIG. 4A, horizontal rectangle in dotted line) and a microstrip line409attached to the bottom of the second substrate layer407. The slot is arranged in the ground plane. The microstrip overlaps with some of the dielectric vias404in plan view. The dielectric resonator antenna400is excited by the slot of width W and length L which is fed by the microstrip line of width Wf. The dielectric resonator antenna400in this embodiment can be excited to various operation modes, including but not limited to HEM11δmode.

FIG. 5shows a simulated electric field pattern of the substrate-integrated dielectric resonator antenna400. As shown inFIG. 5, the field distribution resembles the regular HEM11δ mode of a regular, solid dielectric resonator antenna.

FIG. 6Ashows the simulated change in reflection coefficient (dB) with frequency (Hz) for different lengths (6 mm, 7 mm, 8 mm) of the slot in the substrate-integrated dielectric resonator antenna400.

FIG. 6Bshows the simulated change in realized gain (dBi) with frequency (Hz) for the substrate-integrated dielectric resonator antenna400. As shown inFIG. 6B, the antenna400attains a realized gain of 6 dBi at 10 GHz, which is reasonable for a DRA operating in HEM11δ mode. The antenna400has a −10 dB bandwidth of 11%.

FIGS. 7A and 7Bshow the simulated radiation pattern of the substrate-integrated dielectric resonator antenna400in the E-plane and the H-plane respectively. As shown inFIGS. 7A and 7B, the pattern is omnidirectional as expected from a dielectric resonator antenna operating in the HEM11δ mode.

The structure and device of the above embodiments are advantageous in various aspects. First, the arrangement of dielectric vias as disclosed allow for customization of substrates such as PCB substrates, and for confining and directing electromagnetic energy. The substrate-integrated dielectric resonator antenna embodiment, by integrating the dielectric resonator antenna to the substrate using the dielectric vias, eliminates the problem associated with conventional inaccurate placement of dielectric resonator antenna on top of PCB substrate. The structure with the dielectric vias (e.g., microwave circuits and substrate-integrated dielectric resonator antenna) can be made simply and cost effectively. Other devices such as filters and oscillators can be manufactured in substrate, improving space efficiency and reducing the footprint for electronic components. The use of ceramic, pre-sintered perovskite oxide particles in some embodiments eliminate the need for high temperature sintering, thereby preventing damage to the substrate layer. Utilizing the highly reflective boundary of the wall of dielectric vias, various devices or microwave devices such as substrate-integrated waveguides (SIW), cavities, dielectric resonators, filters, resonating oscillators tank or substrate-integrated dielectric resonator antennas can be designed, with or without other metallic vias or dielectric/metal track. By utilizing the dielectric vias in the substrate-integrated waveguides, the losses occurring in the metallic sidewalls can be spared. This can be especially helpful when operating such a device at radio frequency ranges.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The described embodiments of the invention should therefore be considered in all respects as illustrative, not restrictive.

For example, the shape and form of the substrate or substrate layer can be varied. The thickness of the substrate layer need not be constant. The number, position, shape (e.g., cross sectional), and arrangement of dielectric vias in the substrate can be varied. In some examples, there can be only one dielectric vias. The dielectric vias may be arranged in a regular pattern, e.g., one that has an axis of symmetry, or may be arranged in a random, irregular pattern. The dielectric vias need not be completely filled with dielectric material. Instead, it could be filled partly with or coated with the dielectric material. The dielectric constant of the substrate and the dielectric constant of the dielectric material can take other values, depending on applications, so long as the dielectric constant of the dielectric material is larger than the dielectric constant of the substrate. The dielectric material can be fixed or retained or enclosed in the via-holes using various chemical or mechanical means, not limited to heating or enclosing with material layers as provided above. The upper and lower metallic layers inFIG. 3can be replaced by the dielectric material (paste form or solid form) serving as electric wall. The dielectric resonator antenna can be excited in various ways, not necessarily by or via the slot.