Patent Description:
The present disclosure relates to an apparatus and methods for enhancing isolation of electronic devices and, in particular, to an apparatus and method for providing an advanced manufacturing technology (AMT) copper Faraday wall for microwave isolation enhancement.

Currently, electrical devices that are used for the generation, transmission and reception of certain signals, such as radio frequency (RF) signals, include multi-layer printed circuit boards (PCBs) on which circuits, such as microwave and millimeter wave circuit designs, are disposed. These electrical devices often include conductive vias, sequential laminations and blind vias that require processing which can be a major cost and performance driver.

Currently, PCB shielding techniques often employ the use of ground vias in which through-holes are drilled through the entire board and electroplated in order to create a fence that attenuates higher-order RF modes. In some cases, cavities or channels have been built into PCBs for subsequent electroplating. These techniques have typically involved creating gaps within the multi-layer PCBs and have unnecessary process steps.

<CIT> discloses a circuit assembly, comprising: a printed circuit board, having a circuit element region and defining a continuous trench surrounding an entirety of the circuit element region, wherein the PCB has multiple layers, a circuit element disposed within the circuit element region of the PCB; and a continuous Faraday wall disposed within the trench to surround an entirety of the circuit element. <CIT> discloses a printed circuit board with a continuous trench, in which a continuous Faraday wall comprising a solid, unitary body is disposed to surround an entirety of a circuit element.

According to an aspect of the disclosure, a circuit assembly according to claim <NUM> is provided.

In accordance with additional or alternative embodiments, the circuit element includes one or more of a microwave circuit, an antenna and a radiator.

In accordance with additional or alternative embodiments, the Faraday wall includes a conductive material.

In accordance with additional or alternative embodiments, the Faraday wall has a polygonal shape within a plane of the PCB.

In accordance with additional or alternative embodiments, the Faraday wall includes one or more of corners with complex geometrical shapes, chamfered corners and sides comprising inwardly protruding features.

In accordance with additional or alternative embodiments, the Faraday wall is one or more of soldered and press-fit into a secured position within the trench.

In accordance with additional or alternative embodiments, the trench is defined as multiple trenches surrounding an entirety of the antenna element region and the Faraday wall is provided as multiple Faraday walls respectively disposed within corresponding ones of the multiple trenches.

According to another aspect of the disclosure, a method of assembling a circuit assembly according to claim <NUM> is provided.

In accordance with additional or alternative embodiments, the layering together of the multi-layer printed circuit board (PCB) includes one or more of milling and lazing the multi-layer PCB to define, in the one or more layers thereof, the trench.

In accordance with additional or alternative embodiments, the one or more of the milling and the lazing includes one or more of milling and lazing the multi-layer PCB from an uppermost layer to a desired depth.

In accordance with additional or alternative embodiments, the method further includes one or more of automated cutting, machining, stamping and extruding of the Faraday wall.

In accordance with additional or alternative embodiments, the disposing of the Faraday wall within the trench includes one or more of soldering and press-fitting the Faraday wall into a secured position within the trench.

Additional features and advantages are realized through the techniques of the present invention. For a better understanding of the invention with the advantages and the features, refer to the description and to the drawings.

As will be described below, a circuit assembly is provided with a Faraday wall or, more particularly, a copper Faraday wall. The Faraday wall is a solid, unitary insert feature that is soldered or press-fit into a trench, which is milled or lazed into a printed circuit board (PCB). As opposed to vias, where material is removed and then plated, the Faraday wall insert feature is readily installed in place without chemical processing. The Faraday wall thus forms a barrier which isolates adjacent microwave circuits from one another, acts as a tuning element in a radiator system (e.g., in a low profile array radiator where the Faraday wall can enable the creation of two narrow bands with acceptable performance at an X-band) and/or provides for electrical mode suppression without electroplating. Moreover, while via fences tend to leak at high frequencies, Faraday walls avoid leakage by forming a continuous wall of material.

With reference to <FIG>, a circuit assembly <NUM> is provided and includes a printed circuit board (PCB) <NUM>, a circuit element <NUM> and a Faraday wall <NUM>. While these features are illustrated in <FIG> as being part of a processing yield that can be broken up into multiple devices following fabrication, it is to be understood that this is not necessary and that the circuit assembly <NUM> can be fabricated on an individualized basis as well.

The PCB <NUM> has a circuit element region <NUM> defined in a central portion thereof and is formed to define a trench <NUM>. The trench <NUM> is continuous and surrounds an entirety of the circuit element region <NUM>. The circuit element <NUM> is disposed within the circuit element region <NUM> of the PCB <NUM> and can be provided as one or more of a microwave circuit, an antenna and a radiator (i.e., a circuit/antenna/radiator element) <NUM>. The Faraday wall <NUM> can include a conductive material, such as copper or another suitable metal or metallic alloy, and includes a solid, unitary body <NUM> that has a same shape as the trench <NUM> to thus fit tightly within the trench <NUM>. The Faraday wall <NUM> is disposed within the trench <NUM> and is continuous to surround an entirety of the circuit element <NUM>.

As shown in <FIG> and <FIG>, the PCB <NUM> has multiple layers <NUM>. In these or other cases, one or more of the multiple layers <NUM> defines the trench <NUM> and the Faraday wall <NUM> traverses the one or more of the multiple layers <NUM> in the height-wise dimension DH (see <FIG>) when the Faraday wall <NUM> is disposed within the trench <NUM>. In an exemplary case, the trench <NUM> can be defined by the uppermost ones of the multiple layers <NUM>. Here, a thickness or depth of the trench <NUM> can be equal to or less than the combined thicknesses of the uppermost ones of the multiple layers <NUM> defining the trench <NUM> and can be equal to or greater than the thickness or height of the Faraday wall <NUM>.

Although the details of <FIG> suggest that the depths of the trench <NUM> and that the height of the Faraday wall <NUM> in the height-wise dimension DH exceeds the thickness of the circuit element <NUM>, it is to be understood that this is not required and that other embodiments exist in which this is not the case. For example, the depths of the trench <NUM> and that the height of the Faraday wall <NUM> in the height-wise dimension DH might not exceed the thickness of the circuit element <NUM> as long as electromagnetic radiation leaking from the circuit element <NUM> in the planar dimension DP is substantially blocked by the Faraday wall <NUM>.

As shown in <FIG>, the Faraday wall <NUM> can have a polygonal shape <NUM> within a plane of the PCB <NUM> and can include one or more of corners with complex geometrical shapes <NUM> (see <FIG>), chamfered corners <NUM> (see <FIG>) and sides <NUM> that include inwardly protruding features <NUM> (see <FIG>). As a general matter, the particular shape and combination of features of the Faraday wall <NUM> can be a function of a type, a configuration and an operation of the circuit element <NUM>. For example, in the embodiment of <FIG> in which the circuit element <NUM> is a microwave circuit with a Jerusalem cross configuration, the Faraday wall <NUM> can have the corners with complex geometrical shapes <NUM> (e.g., clockwise or counter-clockwise facing C-shaped features). As another example, as in the embodiment of <FIG>, the Faraday wall <NUM> can have the chamfered corners <NUM> and the sides <NUM> that include inwardly protruding features <NUM> in order to accommodate certain electrical structures such as coaxial cabling and other similar features (e.g., coaxial transverse electromagnetic (TEM) circuit features).

In any case, as shown in <FIG>, the trench <NUM> and the Faraday wall <NUM> are both configured such that the Faraday wall <NUM> fits tightly within the trench <NUM>. Thus, insertion and installation of the Faraday wall <NUM> into the trench <NUM> can be executed by way of a combination of one or more of soldering and press-fitting of the Faraday wall <NUM> into the trench <NUM>.

To whatever extent the Faraday wall <NUM> does not fit tightly within the trench <NUM>, it is to be understood that the Faraday wall <NUM> can be machined or discarded and replaced. In either case, the PCB <NUM> is not affected as it would otherwise be in an electroplating case.

With reference to <FIG>, the trench <NUM> can be defined as multiple trenches <NUM><NUM> and <NUM><NUM> that cooperatively surround the entirety of the antenna element region <NUM>. In these or other cases, the Faraday wall <NUM> can be provided as multiple Faraday walls <NUM><NUM> and <NUM><NUM> that are respectively disposed within corresponding ones of the multiple trenches <NUM><NUM> and <NUM><NUM>.

With reference to <FIG>, a method of assembling a circuit assembly is provided. As shown in <FIG>, the method includes layering together a multi-layer PCB to have, in one or more layers thereof, an antenna element region and to define, in the one or more layers thereof, a trench surrounding an entirety of the antenna element region <NUM>, disposing an antenna element within the antenna element region of the multi-layer PCB <NUM>, automated cutting, machining, stamping and extruding of a Faraday wall <NUM> and disposing, within the trench, the Faraday wall where the Faraday wall includes a solid, unitary body having a same shape as the trench such that the Faraday wall traverses the one or more layers to surround an entirety of the antenna element <NUM>.

In accordance with embodiments, the layering together of the multi-layer PCB of operation <NUM> can include one or more of milling and lazing the multi-layer PCB to define, in the one or more layers thereof, the trench <NUM> and the one or more of the milling and the lazing of operation <NUM> can include one or more of milling and lazing the multi-layer PCB from an uppermost layer to a desired depth. In addition, the disposing of the Faraday wall within the trench of operation <NUM> can include one or more of soldering and press-fitting the Faraday wall into a secured position within the trench <NUM>.

With reference to <FIG>, the method described above with reference to <FIG> will be described in further detail.

As shown in <FIG>, a multi-layer PCB <NUM> is assembled or layered with multiple layers <NUM> having various thicknesses according to various layering or laminating processes and, once the multi-layer PCB <NUM> is assembled, a circuit/antenna/radiator element <NUM> is installed in a circuit/antenna radiator element region as shown in <FIG>.

While <FIG> suggest that the multi-layer PCB <NUM> is assembled prior to the installation of the circuit/antenna/radiator element <NUM>, it is to be understood that this is not required and that embodiments exist in which the circuit/antenna/radiator element <NUM> is built into the multiple layers <NUM> during the layering or laminating processes.

As shown in <FIG>, a trench <NUM> is defined in the multi-layer PCB <NUM>. The trench <NUM> extends continuously around the circuit/antenna/radiator element <NUM>. The trench <NUM> has a depth in the height-wise dimension DH that is equal to or greater than the thickness of the circuit/antenna/radiator element <NUM> although it is to be understood that this is not required and that embodiments exist in which the trench <NUM> has a depth that is lesser than the thickness of the circuit/antenna/radiator element <NUM>.

In accordance with embodiments, the trench <NUM> can be defined by one or more of milling and lazing of the multi-layer PCB <NUM> from an uppermost one of the multiple layers <NUM>, through a next uppermost one of the multiple layers <NUM>, and so on.

As shown in <FIG> and <FIG>, Faraday wall <NUM> is formed by one or more of automated cutting, machining, stamping and extruding processes to tightly fit into the trench <NUM> (see <FIG>) and the Faraday wall <NUM> is subsequently installed within the trench <NUM> by one of soldering and press-fitting (see <FIG>). The resulting circuit assembly <NUM>, which has been assembled without the need for electroplating or other chemical processing, is configured such that electromagnetic radiation leaking from the circuit/antenna/radiator element <NUM> in the planar dimension DP is block by the continuous body of the Faraday wall <NUM>. That is, the Faraday wall <NUM> provides for electrical mode suppression without the need for electroplating techniques being executed.

As such, to the extent that the circuit/antenna/radiator element <NUM> is a microwave circuit adjacent to another microwave circuit, the Faraday wall <NUM> forms a barrier which isolates the adjacent microwave circuits from one another. To the extent that the circuit/antenna/radiator element <NUM> is a radiator element, the Faraday wall <NUM> can act as a tuning elements in an overall radiator system (e.g., a low profile array radiator) in which the Faraday wall <NUM> enables the creation of two narrow bands with acceptable performance at an X-band.

Technical effects and benefits of the present invention are the provision of a circuit assembly with a Faraday wall or, more particularly, a copper Faraday wall that offers a shielding alternative to a via fence and can be assembled using low-cost, high volume fabrication methods that are chemical process free.

The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope of the claims. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

Claim 1:
A circuit assembly (<NUM>), comprising:
a printed circuit board, PCB, (<NUM>) having a circuit element region (<NUM>) and defining a continuous trench (<NUM>) surrounding an entirety of the circuit element region, wherein the PCB has multiple layers (<NUM>);
a circuit element (<NUM>) disposed within the circuit element region of the PCB; and
a continuous Faraday wall (<NUM>) comprising a solid, unitary body (<NUM>) having a same shape as the trench and being disposed within the trench to surround an entirety of the circuit element,
wherein more than one of the multiple layers defines the trench and the Faraday wall traverses the more than one of the multiple layers within the trench.