MULTILAYER SUBSTRATE

• US 20120138340A1
• Filed: 02/09/2012
• Published: 06/07/2012
• Est. Priority Date: 08/11/2009
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: KATO, Noboru, SASAKI, Jun, ISHINO, Satoshi
• Granted Patent: US 8,692,125 B2
• Time in Patent Office: Days
• US Class Current: 174/251
• CPC Class Codes: H05K 1/024 Dielectric details, e.g. changing the dielectric material around a transmission line
• CPC Class Codes: H05K 1/028 Bending or folding regions of flexible printed circuits H05K1/0283 takes precedence
• CPC Class Codes: H05K 1/0281 Reinforcement details thereof
• CPC Class Codes: H05K 1/0298 Multilayer circuits
• CPC Class Codes: H05K 1/032 consisting of one material
• CPC Class Codes: H05K 1/09 Use of materials for the conductive, e.g. metallic pattern
• CPC Class Codes: H05K 2201/0141 Liquid crystal polymer [LCP]
• CPC Class Codes: H05K 2201/057 Shape retainable
• CPC Class Codes: H05K 2201/0715 provided by an outer layer of PCB
• CPC Class Codes: H05K 2201/09018 Rigid curved substrate
• CPC Class Codes: H05K 2201/09409 Multiple rows of pads, lands, terminals or dummy patterns; Multiple rows of mounted components

Abstract

A multilayer substrate that retains a curved state without causing fluctuations in electrical characteristics includes a main body including a plurality of insulating sheets to be stacked and made of a flexible material. A signal wire extends in the main body. A ground conductor is provided at a positive-direction side in a z-axis direction relative to the signal wire in the main body, and overlaps the signal line in a plan view seen from the z-axis direction. A ground conductor is provided on a negative-direction side in the z-axis direction relative to the signal wire in the main body, and overlaps the signal line in a plan view seen from the z-axis direction. The state in which the main body is curved so that the signal wire defines an arc is retained by plastic deformation of the ground conductors.

Claims

1. A multilayer substrate comprising:

a main body including a plurality of insulating sheets to be stacked and made of a flexible material;

a signal wire disposed in the main body;

a first ground conductor that is provided at one side of the signal wire in a stacking direction in the main body, such that the first ground conductor overlaps the signal wire in a plan view seen from the stacking direction; and

a second ground conductor that is provided at the other side of the signal wire in the stacking direction in the main body, such that the second ground conductor overlaps the signal wire in a plan view seen from the stacking direction;

wherein

the main body including the signal wire retains a curved state by plastic deformation of the first and second ground conductors.

2. The multilayer substrate according to claim 1, wherein when the main body including only one of the first and second ground conductors is curved, the curved state of the main body cannot be retained by plastic deformation of the first ground conductor or the second ground conductor.

3. The multilayer substrate according to claim 1, wherein the main body is curved to project toward the other side in the stacking direction, the first ground conductor is plastically deformed in a state of contracting in a direction in which the signal wire extends, and the second ground conductor is plastically deformed in a state of expanding in the direction in which the signal wire extends.

4. The multilayer substrate according to claim 3, wherein expansion/contraction does not occur at specified positions on the insulating sheets when the main body is curved, the first ground conductor is provided on the one side in the stacking direction relative to the specified position, and the second ground conductor is provided on the other side in the stacking direction relative to the specified position.

5. The multilayer substrate according to claim 1, wherein each of the insulating sheets has a Young'"'"'s modulus of about 2 GPa to about 30 GPa, and the signal wire and the first and second ground conductors have a Young'"'"'s modulus of about 100 GPa to about 150 GPa.

6. The multilayer substrate according to claim 1, wherein each of the insulating sheets is made of a liquid-crystal polymer, and the signal wire and the first and second ground conductors are made of copper layers.

7. The multilayer substrate according to claim 1, wherein a thickness of the first and second ground conductors in the stacking direction is about 5 μ

m to about 25 μ

m.

8. The multilayer substrate according to claim 1, wherein spacing between the first and second ground conductors in the stacking direction is about 50 μ

m to about 200 μ

m.

9. The multilayer substrate according to claim 1, wherein the main body is curved to project toward the other side in the stacking direction, and the first ground conductor is sandwiched between the insulating sheets from the stacking direction, and attached more weakly to the insulating sheet lying on one side in the stacking direction than to the insulating sheet lying on the other side in the stacking direction.