3D Bendable Printed Circuit Board With Redundant Interconnections

• US 20170118838A1
• Filed: 10/21/2015
• Published: 04/27/2017
• Est. Priority Date: 10/21/2015
• Status: Active Grant

• Current Assignee: Adventive International Limited
• Original Assignee: Adventive Ipbank
• Inventors: Williams, Richard K., Lin, Keng Hung
• Granted Patent: US 10,064,276 B2
• Time in Patent Office: Days
• CPC Class Codes: H05K 1/147 at least one of the printed circuits being bent or folded, e.g. by using a flexible printed circuit H05K1/148 takes precedence
• CPC Class Codes: H05K 1/148 Arrangements of two or more hingeably connected rigid printed circuit boards, i.e. connected by flexible means
• CPC Class Codes: H05K 2201/052 Branched
• CPC Class Codes: H05K 2201/056 Folded around rigid support or component
• CPC Class Codes: H05K 2201/058 Direct connection between two or more FPCs or between flexible parts of rigid PCBs
• CPC Class Codes: H05K 2201/09245 Crossing layout alternating conductors H05K2201/097
• CPC Class Codes: H05K 2201/09254 Branched layout
• CPC Class Codes: H05K 2201/0979 Redundant conductors or connections, i.e. more than one current path between two points
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]
• CPC Class Codes: H05K 2201/2009 Reinforced areas, e.g. for a specific part of a flexible printed circuit
• CPC Class Codes: H05K 2203/1327 Moulding over PCB locally or completely applying non-metallic protective coatings for encapsulating mounted components H05K3/284
• CPC Class Codes: H05K 3/0026 by laser ablation
• CPC Class Codes: H05K 3/0035 of blind holes, i.e. having a metal layer at the bottom
• CPC Class Codes: H05K 3/027 the conductive material being removed by irradiation, e.g. by photons, alpha or beta particles
• CPC Class Codes: H05K 3/06 the conductive material being removed chemically or electrolytically, e.g. by photo-etch process semi-additive methods H05K3/108
• CPC Class Codes: H05K 3/061 Etching masks
• CPC Class Codes: H05K 3/188 by direct electroplating
• CPC Class Codes: H05K 3/24 Reinforcing the conductive pattern by solder coating H05K3/3457
• CPC Class Codes: H05K 3/32 electrically connecting electric components or wires to printed circuits
• CPC Class Codes: H05K 3/361 Assembling flexible printed circuits with other printed circuits
• CPC Class Codes: H05K 3/4038 : Through-connections; Vertical interconnect access [VIA] connections H05K3/403, H05K3/42 take precedence
• CPC Class Codes: H05K 3/4691 : Rigid-flexible multilayer circuits comprising rigid and flexible layers, e.g. having in the bending regions only flexible layers

Abstract

A rigid-flex PCB includes an array of rigid PCB “islands” interconnected by a flexible PCB formed into flexible connectors. The conductive and insulating layers of the flexible PCB extend into the rigid PCBs, giving the electrical connections to the rigid PCBs added resistance to breakage as the rigid-flex PCB is repeatedly stressed by bending and twisting forces. In addition, the durability of the rigid-flex PCB is enhanced by making the power and signal lines driving the rigid PCBs redundant so that a breakage of a line will not necessarily affect the operation of the rigid PCB to which it is attached. The rigid-flex PCB is particularly applicable to light pads used in phototherapy, wherein LEDs mounted on the rigid-PCBs are powered and controlled through the redundant lines in the flexible PCB.

Claims

1. A rigid-flex printed circuit board (PCB) comprising an array of rigid printed circuit boards (PCBs), the array comprising a rigid PCB connected to at least two electrical lines, each of said lines designed to carry a single power voltage or a single electrical signal.

2. The rigid-flex PCB of claim 1 wherein the lines are comprised within a flexible PCB.

3. The rigid-flex PCB of claim 2 wherein the at least two electrical lines comprise a first line and a second line, the first line being electrically connected to a second rigid PCB in the array through a first flexible connector, the second line being connected to a third rigid PCB in the array through a second flexible connector, the first and second flexible connectors being comprised within the flexible PCB.

4. The rigid-flex PCB of claim 3 wherein the rigid PCB is connected to a third line, the third line being designed to carry the same power voltage or electrical signal as the first and second lines, the second line being connected to a fourth rigid PCB in the array through a third flexible connector, the third flexible connector being comprised with the flexible PCB.

5. The rigid-flex PCB of claim 4 further comprising a metal support layer physically connected to the rigid PCB and extending over the first flexible connector.

6. A rigid-flex PCB comprising a rigid PCB and a flexible PCB, the rigid PCB comprising:

a patterned conductive layer attached to a first side of a rigid insulating layer;

a flexible conductive layer attached to a second side of the rigid insulating layer; and

a flexible insulating layer attached to the flexible insulating layer;

the flexible PCB comprising;

the flexible conductive layer; and

the flexible insulating layer.

7. The rigid-flex PCB of claim 6 further comprising a second flexible insulating layer between the rigid insulating layer and the flexible conductive layer in the rigid PCB, the second flexible insulating layer extending into the flexible PCB.

8. A rigid-flex PCB comprising an array of rigid PCBs in a square grid design and a flexible PCB comprising a plurality of flexible connectors connecting each of the rigid PCBs to its four closest neighboring rigid PCBs to form an orthogonal web of flexible connectors of the kind shown in FIG. 60A.

9. The rigid-flex PCB of claim 8 further comprising a plurality of diagonal flexible connectors forming a web of the kind shown in FIG. 60B.

10. The rigid-flex PCB of claim 8 further comprising a plurality of diagonal flexible connectors forming a web of the kind shown in FIG. 60C.

11. A method of fabricating rigid-flex PCB comprising:

attaching a flexible protective cap insulating layer to a flexible conductive layer;

attaching a PCB conductive layer to a rigid insulating layer;

attaching the rigid insulating layer to the flexible protective cap insulating layer;

patterning the PCB conductive layer to form a patterned conductive layer in an area where a rigid PCB is to be located; and

removing a portion of the rigid insulating layer in an area where a flexible PCB is to be located.

12. The method of claim 11 further comprising removing a portion of the flexible protective cap insulating layer and a portion of the flexible conductive layer in an area where neither the rigid PCB nor the flexible PCB is to be located, thereby to form a flexible connector.

13. The method of claim 11 wherein removing a portion of the flexible protective cap insulating layer and a portion of the flexible conductive layer is performed using a laser beam.

14. The method of claim 11 further comprising:

forming a via through the rigid insulating layer and the flexible protective cap insulating layer so as to expose the flexible conductive layer, and

depositing a conductive material in the via so as to form an electrical connection between the patterned conductive layer and the flexible conductive layer.

15. The method of claim 11 further comprising plating a metal layer on the patterned conductive layer.

16. The method of claim 11 further comprising:

depositing an interfacial layer on the flexible protective cap layer; and

treating the interfacial layer so as to selectively harden a portion of the interfacial layer in the rigid PCB while leaving a portion of the interfacial layer in the flexible PCB in a less rigid state.

17. The method of claim 11 further comprising removing the portion of the interfacial layer that was left in a less rigid state.

18. The method of claim 11 further comprising mounting an LED on the rigid PCB.

19. The method of claim 18 further comprising encasing the rigid PCB and the flexible PCB in a polymeric pad, the polymeric pad having openings adjacent to the LED.

20. The method of claim 11 further comprising:

forming a mask layer on the flexible conductive layer, the mask layer being in the form of a mesh having openings; and

etching the flexible conductive layer through the openings in the mask layer to form a conductive mesh.