Systems, articles, and methods for stretchable printed circuit boards

• US 9,788,789 B2
• Filed: 08/28/2014
• Issued: 10/17/2017
• Est. Priority Date: 08/30/2013
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Thalmic Labs Inc.
• Inventors: Bailey, Matthew
• Primary Examiner(s): MILAKOVICH, NATHAN J
• Application Number:
  US14/471,982
• Publication Number:
  US 20150065840A1
• Time in Patent Office: 1,146 Days
• CPC Class Codes: A61B 5/296 for electromyography [EMG]
• CPC Class Codes: A61B 5/6802 Sensor mounted on worn items
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6822 Neck
• CPC Class Codes: A61B 5/6823 Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6828 Leg
• CPC Class Codes: A61B 5/6829 Foot or ankle
• CPC Class Codes: H05K 1/0283 Stretchable printed circuits
• 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 2201/0154 Polyimide
• CPC Class Codes: H05K 2201/09063 Holes or slots in insulating substrate not used for electrical connections
• CPC Class Codes: H05K 2201/09263 Meander

Abstract

Improved stretchable printed circuit boards, and fabrication methods thereof, are described. The improved stretchable printed circuit boards include a serpentine conductive trace enclosed by stretchable dielectric material. The stretchable dielectric material has a serpentine shape itself, realized by crenulated edges. The crenulated edges reduce torsional strain on the conductive trace and are formed, for example, by cutting away sections of the stretchable dielectric material proximate segments of the serpentine conductive trace where the serpentine conductive trace changes direction.

Claims

1. A method of fabricating a stretchable printed circuit board, the method comprising:

fabricating a flexible printed circuit board, wherein fabricating a flexible printed circuit board comprises;

depositing a layer of flexible dielectric material;

depositing a layer of conductive metal on top of the flexible dielectric material; and

etching a circuit pattern into the layer of conductive metal, wherein the circuit pattern includes at least one serpentine conductive trace that includes a plurality of changes in direction,

removing at least some portions of the flexible dielectric material that are not covered by the at least one serpentine conductive trace; and

enclosing at least a portion of the flexible printed circuit board in a stretchable dielectric material, wherein the stretchable dielectric material forms a crenulated shape that includes a plurality of crenulations across a length thereof, wherein each crenulation is positioned proximate and corresponds to a respective change in direction in the at least one serpentine conductive trace, and wherein enclosing at least a portion of the flexible printed circuit board in a stretchable dielectric material comprises;

placing the flexible printed circuit board into a mold that provides a crenulated shape for the stretchable dielectric material;

injecting the stretchable dielectric material, in liquid form, into the mold;

solidifying the stretchable dielectric material; and

removing the mold.

2. The method of claim 1 wherein removing at least some portions of the flexible dielectric material that are not covered by the at least one serpentine conductive trace includes cutting away the at least some portions of the flexible dielectric material that are not covered by the at least one serpentine conductive trace.