Systems and methods for EMI shielding
Various technologies described herein pertain to systems and methods for shielding electric circuits from electromagnetic radiation or radio waves. The systems and methods include, for example, a shield having a body with a top portion and a plurality of side portions extending therefrom. The side portions include one or more extensions acting as spring contacts or spring elements and one or more gaps therebetween. The extensions are, for example, either individually or as a group flexible in that they can compress, bend, or otherwise deform under force thus having a spring characteristic that compensates for PCB irregularities (e.g., warping, bending, etc.).
1 . An electrical system, comprising:
a printed circuit board comprising an electrical circuit having electro-magnetic radio frequency emissions;
a shield having a top portion and a plurality of side portions connected to the top portion and surrounding the electrical circuit; and
a mask layer having a conductive material and a cavity comprising the shield and the electrical circuit;
wherein the plurality of side portions comprise spring contacts and gaps, wherein:
each of the spring contacts is integrally formed with a respective side portion of the plurality of side portions,
one or more of the gaps is integrally formed in a respective side portion of the plurality of side portions and is disposed between consecutive spring contacts comprised among the spring contacts,
each of the spring contacts comprise a compressed state when contacting a reference circuit of the printed circuit board, and
at least one of the spring contacts comprises a first section and a second section,
wherein, when the shield is compressed, one or more of the first section and the second section deflect at a junction between the first section and the second section such that:
the first section contacts at least the reference circuit, and the second section contacts an inner side surface of the mask layer; or
the first section contacts at least the inner side surface of the mask layer, and the second section contacts at least the reference circuit,
wherein the inner side surface of the mask layer corresponds to a boundary of the cavity.
2 . The electrical system of claim 1 , wherein the one or more of the gaps comprises an approximate gap width according to the following:
w
<
A
/
30
wherein w comprises the approximate gap width and A comprises a wavelength of electromagnetic radiation to be shielded.
3 . The electrical system of claim 1 , wherein one or more of the spring contacts comprises an approximate pitch according to the following:
d
=
n
(
A
4
)
wherein d comprises an approximate pitch, n comprises an integer greater than zero (0), and A comprises a wavelength of electromagnetic radiation to be shielded.
4 . The electrical system of claim 1 , wherein the top portion comprises an opening for allowing at least a portion of a thermal interface material to extend therethrough and contact the electrical circuit.
5 . The electrical system of claim 1 , wherein the top portion comprises a planar surface portion for contacting at least a portion of a thermal interface material.
6 . The electrical system of claim 1 , further comprising a mask layer having a conductive material and a cavity comprising the shield and the electrical circuit.
7 . The electrical system of claim 1 , further comprising:
a thermal interface material between the mask layer and electrical circuit and extending through an opening in the top portion of the shield.
8 . The electrical system of claim 1 , wherein the shield comprises a metal material.
9 . The electrical system of claim 1 , wherein the shield comprises a body having a conductive coating.
10 . A radar system, comprising:
a printed circuit board comprising a radar circuit having electro-magnetic radio frequency emissions;
a metal shield having a top portion and a perimeter connected to the top portion and at least partially surrounding the radar circuit; and
a mask layer having a conductive material and a cavity comprising the metal shield and electrical circuit;
wherein the perimeter comprises spring elements and gaps, wherein:
each of the spring elements is integrally formed with a respective portion of the perimeter;
one or more of the gaps is integrally formed in a respective portion of the perimeter and is disposed between consecutive spring elements comprised among the spring elements; and
each of the spring elements comprise a bent position when contacting a reference circuit of the printed circuit board; and
at least one of the spring elements comprises a first section and a second section,
wherein, when the metal shield is compressed, one or more of the first section and the second section deflect at a junction between the first section and the second section such that:
the first section contacts at least the reference circuit, and the second section contacts an inner side surface of the mask layer; or
the first section contacts at least the inner side surface of the mask layer, and the second section contacts at least the reference circuit,
wherein the inner side surface of the mask layer corresponds to a boundary of the cavity.
11 . The radar system of claim 10 , wherein the spring elements comprise at least one continuous spring element.
12 . The radar system of claim 10 , wherein the consecutive spring elements are divided by the one or more of the gaps.
13 . The radar system of claim 10 , further comprising:
a thermal interface material between the mask layer and electrical circuit and extending through an opening in the top portion of the metal shield.
14 . The radar system of claim 10 , wherein the top portion comprises a rectangular shape and includes a rectangular opening therein.
15 . The radar system of claim 10 , wherein the one or more of the gaps comprises an approximate gap width according to the following:
w
<
A
/
30
wherein w comprises the approximate gap width and A comprises a wavelength of electromagnetic radiation to be shielded.
16 . The radar system of claim 10 , wherein one or more of the spring elements comprises an approximate pitch according to the following:
d
=
n
(
A
4
)
wherein d comprises an approximate pitch, n comprises an integer greater than zero (0), and A comprises a wavelength of electromagnetic radiation to be shielded.
17 . A method of forming a shielded electrical circuit comprising steps of:
providing a printed circuit board having a circuit that generates electromagnetic radio frequency emissions;
placing a metal shield on the printed circuit board, the metal shield having a top portion and a plurality of side portions connected to the top portion and surrounding the circuit, wherein:
the plurality of side portions comprise spring elements and gaps;
each of the spring elements is integrally formed with a respective side portion of the plurality of side portions; and
one or more of the gaps is integrally formed in a respective portion of the plurality of side portions and is disposed between consecutive spring elements comprised among the spring elements;
wherein placing the metal shield on the printed circuit board comprises steps of compressing the spring elements of the metal shield thereby placing one or more of the spring elements in contact with an electrical reference circuit of the printed circuit board, and wherein compressing the spring elements comprises bending the spring elements; and
securing the metal shield on the printed circuit board by placing the metal shield within a cavity of a conductive mask layer of the printed circuit board,
wherein the compressing the spring elements comprises compressing each of the spring elements until:
a first section of the spring element contacts at least the electrical reference circuit, and a second section of the spring element contacts an inner side surface of the conductive mask layer; or
the first section contacts at least the inner side surface of the conductive mask layer, and the second section contacts at least the electrical reference circuit,
wherein the inner side surface of the conductive mask layer corresponds to a boundary of the cavity.
18 . The method of claim 17 , further comprising a step of placing a thermal interface material between the circuit and the mask layer.