Flexible printed circuit cable assembly with electromagnetic shielding

Patent metadata

Field	Value
Publication number	US-12101873-B2
Application number	US-202217660618-A
Country	US
Kind code	B2
Filing date	Apr 25, 2022
Priority date	Apr 25, 2022
Publication date	Sep 24, 2024
Grant date	Sep 24, 2024

Abstract

An FPC cable assembly is provided that includes a first ground layer, a second ground layer, and at least one signal line sandwiched by the first and second ground layers. The FPC cable assembly further includes an electromagnetic shielding structure including a first magnetic layer at least partially covering and electrically grounded to the first ground layer, a second magnetic layer at least partially covering and electrically grounded to the second ground layer, and a plurality of magnetic rings magnetically engaged with and electrically contacting the first magnetic layer and the second magnetic layer so as to surround the first and second ground layers, the at least one signal line, and the first and second magnetic layers, thereby providing electromagnetic shielding of the at least one signal line.

First claim

The invention claimed is:

1. A flexible printed circuit (FPC) cable assembly comprising:
an FPC cable including:
a first ground layer;
a second ground layer;
at least one signal line sandwiched by the first ground layer and the second ground layer; and

an electromagnetic shielding structure configured to electromagnetically shield the FPC cable, the electromagnetic shielding structure including:
a first magnetic layer at least partially covering the first ground layer on an outside thereof and being electrically grounded to the first ground layer;
a second magnetic layer at least partially covering the second ground layer on an outside thereof and being electrically grounded to the second ground layer; and
a plurality of magnetic rings magnetically engaged with and electrically contacting the first magnetic layer and the second magnetic layer so as to surround the first and second ground layers, the at least one signal line, and the first and second magnetic layers, wherein

the plurality of magnetic rings are spaced apart from each other along the at least one signal line.

2. The FPC cable assembly of claim 1 , wherein
the first magnetic layer is a first hard magnetic layer;
the second magnetic layer is a second hard magnetic layer; and
the plurality of magnetic rings are a plurality of soft magnetic rings.

3. The FPC cable assembly of claim 2 , wherein
the first and second hard magnetic layers have a hard coercivity which is higher than a coercivity threshold; and
the plurality of soft magnetic rings have a soft coercivity which is lower than the hard coercivity.

4. The FPC cable assembly of claim 3 , wherein
the soft magnetic rings comprise at least one of Fe or Ni—Fe; and
the first and second hard magnetic layers comprise at least one of Sm—Co or NdFeB.

5. The FPC cable assembly of claim 1 , wherein
the plurality of magnetic rings includes a plurality of pairs of adjacent magnetic rings;
each pair of adjacent magnetic rings are separated by a respective distance d, defined by the formula:
d≤c /(4 f ),

where c is the speed of light and f is a largest frequency of radiated emissions from the FPC cable assembly.

6. The FPC cable assembly of claim 5 , wherein
in at least a first section of the FPC cable assembly, the distance separating the adjacent pairs of the plurality of magnetic rings is a first predetermined distance.

7. The FPC cable assembly of claim 6 , wherein
in at least a second section of the FPC cable assembly, the distance separating the adjacent pairs of the plurality of magnetic rings is a second predetermined distance that is larger than the first predetermined distance.

8. The FPC cable assembly of claim 6 , wherein widths of the plurality of magnetic rings in the first section are greater than widths of the plurality of magnetic rings in a second section of the FPC cable assembly.

9. The FPC cable assembly of claim 1 , wherein
in at least a first section of the FPC cable assembly, the adjacent pairs of the plurality of magnetic rings are separated by a first set of distances that vary from each other.

10. The FPC cable assembly of claim 9 , wherein
in at least a second section of the FPC cable assembly, the adjacent pairs of the plurality of magnetic rings are separated by a second set of distances that vary from each other and all of which are larger than the distances in the first set.

11. An electronic device, comprising:
a housing;
a wireless radio transceiver mounted in the housing;
a first electronic component mounted in the housing;
a second electronic component mounted in the housing; and
a flexible printed circuit cable assembly configured at least partially bend to connect the first electronic component to the second electronic component, the FPC cable assembly including:
an FPC cable including:
a first ground layer;
a second ground layer;
at least one signal line sandwiched by the first ground layer and the second ground layer; and

an electromagnetic shielding structure configured to electromagnetically shield the flexible printed circuit cable so as to inhibit an effect of electromagnetic interference from the at least one signal line on an operation of the wireless radio transceiver, the electromagnetic shielding structure including:
a first magnetic layer at least partially covering the first ground layer on an outside thereof and being electrically grounded to the first ground layer;
a second magnetic layer at least partially covering the second ground layer on an outside thereof and being electrically grounded to the second ground layer; and
a plurality of magnetic rings magnetically engaged with and electrically contacting the first magnetic layer and the second magnetic layer so as to surround the first and second ground layers, the at least one signal line, and the first and second magnetic layers, wherein

the plurality of magnetic rings are spaced apart from each other along the at least one signal line.

12. The electronic device of claim 11 , wherein
the first electronic component is a printed circuit board;
the second electronic component is a display or a printed circuit board.

13. The electronic device of claim 11 , further comprising:
a hinge, wherein
the housing includes a first housing portion and a second housing portion configured to rotate relative to each other about the hinge; and
the FPC cable assembly is configured to bend around the hinge.

14. The electronic device of claim 11 , wherein
the first magnetic layer is a first hard magnetic layer;
the second magnetic layer is a second hard magnetic layer;
the plurality of magnetic rings are a plurality of soft magnetic rings;
the first and second hard magnetic layers have a hard coercivity which is higher than a coercivity threshold; and
the plurality of soft magnetic rings have a soft coercivity which is lower than the hard coercivity.

15. The electronic device of claim 14 , wherein
the plurality of magnetic rings includes a plurality of pairs of adjacent magnetic rings;
each pair of adjacent magnetic rings are separated by a respective distance d, defined by the formula:
d≤c /(4 f ),

where c is the speed of light and f is a largest frequency of radiated emissions from the FPC cable assembly.

16. The electronic device of claim 15 , wherein
the FPC cable assembly includes a first section and a second section,
the second section is configured to bend around the hinge, and
each respective distance between each pair of adjacent rings in the second section is larger than each respective distance between each pair of adjacent rings in the first section.

17. The electronic device of claim 16 , wherein
the respective distances between adjacent rings in the first section are a first predetermined distance in length, and
the respective distances between the adjacent rings in the second section are a second predetermined distance in length that is larger than the first predetermined distance in length.

18. The electronic device of claim 16 , wherein widths of the plurality of magnetic rings in the first section are greater than widths of the plurality of magnetic rings in the second section.

19. The electronic device of claim 15 , wherein
the adjacent pairs of the plurality of magnetic rings are separated by a first set of distances that vary from each other.

20. A method of manufacturing a flexible printed circuit (FPC) cable assembly, the method comprising:
providing an FPC cable with a first ground layer, a

Assignees

• Microsoft Technology Licensing Llc

Inventors

• Lee Jaejin
• Leacock Edward Charles
• Khawand Charbel

Classifications

• H05K2201/083

  Magnetic materials · CPC title

• H05K2201/08

  Magnetic details · CPC title

• H05K2201/05

  Flexible printed circuits [FPCs] · CPC title

• H05K1/189

  characterised by the use of flexible or folded printed circuits · CPC title

• H05K1/18

  structurally associated with non-printed electric components (H05K1/16 takes precedence) · CPC title