Solenoid filter built into a printed circuit board

Patent metadata

Field	Value
Publication number	US-10285259-B2
Application number	US-201715632108-A
Country	US
Kind code	B2
Filing date	Jun 23, 2017
Priority date	Jun 23, 2017
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

Disclosed herein are printed circuit boards with embedded solenoid filters through which signal traces pass to filter unwanted noise and electromagnetic interference. A printed circuit board comprises a least three layers, a solenoid embedded within the at least three layers, and at least one trace extending through the solenoid. The insertion loss characteristics of the solenoid filter can be tuned by modifying the number of turns in the solenoid(s) and the width of the solenoid(s). The solenoid filter may comprise multiple solenoids connected in series, with adjacent solenoids having opposite wind directions. Surface components may be included on the board to tune the insertion loss further.

First claim

What is claimed is:

1. A printed circuit board, comprising:
a first layer comprising:
a first solenoid trace and a second solenoid trace of a first solenoid, each of the first and second solenoid traces having a first end and a second end, wherein the first solenoid trace is oriented substantially parallel to the second solenoid trace in a plane of the first layer,
a fifth solenoid trace and a sixth solenoid trace of a second solenoid, each of the fifth and sixth solenoid traces having a first end and a second end, wherein the fifth solenoid trace is oriented substantially parallel to the sixth solenoid trace in the plane of the first layer, and wherein the fifth and sixth solenoid traces are at an angle to the first and second solenoid traces;

a second layer comprising:
a third solenoid trace and a fourth solenoid trace of the first solenoid, each of the third and fourth solenoid traces having a first end and a second end, wherein the third solenoid trace is oriented substantially parallel to the fourth solenoid trace in a plane of the second layer, the plane of the second layer being parallel to the plane of the first layer, and
a seventh solenoid trace and an eighth solenoid trace of the second solenoid, each of the seventh and eighth solenoid traces having a first end and a second end, wherein the seventh solenoid trace is oriented substantially parallel to the eighth solenoid trace in the plane of the second layer, and wherein the seventh and eighth solenoid traces are at an angle to the third and fourth solenoid traces; and

at least one middle layer between the first and second layers, the at least one middle layer comprising:
at least one signal trace, and
a plurality of vias extending through the at least one middle layer in a direction substantially perpendicular to a plane of the at least one middle layer, the plane of the at least one middle layer being parallel to the plane of the first layer, the plurality of vias including a first via, a second via, a third via, a fourth via, a fifth via, and a sixth via,

wherein:
the second end of the first solenoid trace is connected to the second end of the third solenoid trace by the first via,
the first end of the third solenoid trace is connected to the first end of the second solenoid trace by the second via,
the second end of the second solenoid trace is connected to the second end of the fourth solenoid trace by the third via,
the second end of the fifth solenoid trace is connected to the second end of the seventh solenoid trace by the fourth via,
the first end of the fifth solenoid trace is connected to the first end of the eighth solenoid trace by the fifth via,
the second end of the sixth solenoid trace is connected to the second end of the eighth solenoid trace by the sixth via,
the at least one signal trace extends between the first and second vias and between the fourth and fifth vias in a direction substantially parallel to an axis extending in the plane of the at least one middle layer from the first via to the third via, and
the first and second solenoids are connected in series.

2. The printed circuit board recited in claim 1 , wherein:
the first layer further includes a ninth solenoid trace having a first end and a second end, wherein the ninth solenoid trace is oriented substantially parallel to the first and second solenoid traces in the plane of the first layer;
the at least one middle layer further comprises a seventh via and an eighth via, each of the seventh and eighth vias extending through the at least one middle layer in the direction substantially perpendicular to the plane of the second layer; and
the second layer further includes a tenth solenoid trace having a first end and a second end, wherein the tenth solenoid trace is oriented substantially parallel to the third and fourth solenoid traces in the plane of the second layer,

wherein:
the first end of the fourth solenoid trace is connected to the first end of the ninth solenoid trace by the seventh via, and
the second end of the ninth solenoid trace is connected to the second end of the tenth solenoid trace by the eighth via.

3. The printed circuit board recited in claim 1 , wherein the at least one middle layer comprises a plurality of layers, and wherein each of the plurality of vias extends through each of the plurality of layers.

4. The printed circuit board recited in claim 1 , wherein the at least one signal trace comprises at least two signal traces.

5. The printed circuit board recited in claim 1 , wherein the at least one signal trace is a single-ended trace.

6. The printed circuit board recited in claim 1 , wherein the at least one signal trace is configured to provide power to at least a portion of the printed circuit board.

7. The printed circuit board recited in claim 1 , wherein:
the first layer comprises at least eight solenoid traces, including the first and second solenoid traces,
the second layer comprises at least eight solenoid traces, including the third and fourth solenoid traces, and
the plurality of vias includes at least sixteen vias, including the first, second, and third vias.

8. A data storage device comprising the printed circuit board recited in claim 1 .

9. A printed circuit board, comprising:
at least three layers;
a first solenoid embedded within the at least three layers;
a second solenoid embedded within the at least three layers; and
at least one trace extending through the first solenoid and the second solenoid,

wherein:
a wind direction of the second solenoid is opposite a wind direction of the first solenoid.

10. The printed circuit board recited in claim 9 , wherein the at least one trace is configured to carry a single-ended signal.

11. The printed circuit board recited in claim 10 , wherein the single-ended signal is a power signal.

12. The printed circuit board recited in claim 9 , wherein the at least three layers include a first layer, a second layer, and at least one middle layer, and wherein the first solenoid comprises:
a first plurality of solenoid traces on the first layer, all of the first plurality of solenoid traces oriented substantially parallel to each other;
a second plurality of solenoid traces on the second layer, all of the second plurality of solenoid traces oriented substantially parallel to each other; and
a plurality of vias extending perpendicularly through the at least one middle layer, the plurality of vias coupling the first plurality of solenoid traces to the second plurality of solenoid traces.

13. The printed circuit board recited in claim 12 , wherein the plurality of vias is a first plurality of vias, and wherein the second solenoid comprises:
a third plurality of solenoid traces on the first layer, all of the third plurality of solenoid traces oriented substantially parallel to each other;
a fourth plurality of solenoid traces on the second layer, all of the fourth plurality of solenoid traces oriented substantially parallel to each other; and
a second plurality of vias extending perpendicularly through the at least one middle layer, the second plurality of vias coupling the third plurality of solenoid traces to the fourth plurality of solenoid traces.

14. A data storage device comprising the printed circuit board recited in claim 9 .

Assignees

• Western Digital Tech Inc

Inventors

• Wallash Albert
• Contreras John
• Parkinen Ronald G
• Xing Xinzhi
• He Hui

Classifications

• H05K1/0233 Primary

  Filters, inductors or a magnetic substance · CPC title

• H01F17/0013

  with stacked layers · CPC title

• H03H7/0115

  comprising only inductors and capacitors (H03H7/075, H03H7/09, H03H7/12, H03H7/13 take precedence) · CPC title

• H01F2017/002

  Details of via holes for interconnecting the layers · CPC title

• H01P1/2007 Primary

  Filtering devices for biasing networks or DC returns · CPC title