Strain isolation structures for stretchable electronics

• US 9,226,402 B2
• Filed: 03/15/2013
• Issued: 12/29/2015
• Est. Priority Date: 06/11/2012
• Status: Active Grant

• Current Assignee: Medidata Solutions Incorporated (Dassault Systemes SA)
• Original Assignee: MC10, Inc.
• Inventors: Hsu, Yung-Yu
• Primary Examiner(s): Nguyen, Hoa C
• Assistant Examiner(s): Tran, Binh
• Application Number:
  US13/843,873
• Publication Number:
  US 20140240932A1
• Time in Patent Office: 1,019 Days
• Field of Search: 361/748, 361/749, 361/750, 361/751, 361/760, 361/761, 361/762, 361/764, 361/765, 361/776, 361/783, 174/521, 174/251, 174/254, 174/255, 174/256
• US Class Current: 1/1
• CPC Class Codes: H05K 1/0271 Arrangements for reducing stress or warp in rigid printed circuit boards, e.g. caused by loads, vibrations or differences in thermal expansion
• CPC Class Codes: H05K 1/028 Bending or folding regions of flexible printed circuits H05K1/0283 takes precedence
• CPC Class Codes: H05K 1/0283 Stretchable printed circuits
• CPC Class Codes: H05K 1/036 Multilayers with layers of different types
• CPC Class Codes: H05K 1/0393 Flexible materials H05K1/038 takes precedence; specific organic compositions are classified in H05K1/0313 and subgroups
• CPC Class Codes: H05K 1/09 Use of materials for the conductive, e.g. metallic pattern
• CPC Class Codes: H05K 1/118 specially for flexible printed circuits, e.g. using folded portions
• 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 1/185 Components encapsulated in the insulating substrate of the printed circuit or incorporated in internal layers of a multilayer circuit semiconductor chips encapsulated by interconnect and support structures H01L23/5389, H01L24/00
• CPC Class Codes: H05K 1/189 characterised by the use of a flexible or folded printed circuit H05K3/326 takes precedence
• CPC Class Codes: H05K 2201/0133 Elastomeric or compliant polymer elastomeric conductor H05K2201/0314
• CPC Class Codes: H05K 2201/0154 Polyimide
• CPC Class Codes: H05K 2201/0187 with regions of different dielectrics in the same layer, e.g. in a printed capacitor for locally changing the dielectric properties
• CPC Class Codes: H05K 2201/09245 Crossing layout alternating conductors H05K2201/097
• CPC Class Codes: H05K 2201/1028 Thin metal strips as connectors or conductors
• CPC Class Codes: H05K 2201/10287 Metal wires as connectors or conductors
• CPC Class Codes: H05K 2201/2009 Reinforced areas, e.g. for a specific part of a flexible printed circuit
• 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
• CPC Class Codes: H05K 3/4694 Partitioned multilayer circuits having adjacent regions with different properties, e.g. by adding or inserting locally circuit layers having a higher circuit density H05K3/4691 takes precedence

Abstract

Buffer structures are provided that can be used to reduce a strain in a conformable electronic system that includes compliant components in electrical communication with more rigid device components. The buffer structures are disposed on, or at least partially embedded in, the conformable electronic system such that the buffer structures overlap with at least a portion of a junction region between a compliant component and a more rigid device component. The buffer structure can have a higher value of Young'"'"'s modulus than an encapsulant of the conformable electronic system.

Claims

1. An apparatus comprising:

a device component;

a conductive stretchable interconnect electrically coupled with the device component at a junction region, the conductive stretchable interconnect being positioned in a first layer of the apparatus;

a buffer structure positioned in a second layer of the apparatus that is spaced from the first layer of the apparatus, the buffer structure being formed from a non-conductive material; and

an encapsulant encapsulating the device component and the junction region.

2. The apparatus of claim 1, wherein the buffer structure has an annular shape with an inner edge surface defining an inner diameter of the annular shape and an outer edge surface defining an outer diameter of the annular shape.

3. The apparatus of claim 2, wherein the inner edge surface of the buffer structure is horizontally offset from the junction region in a first direction, and wherein the outer edge surface of the buffer structure is horizontally offset from the junction region in a second opposing direction.

4. The apparatus of claim 3, wherein the device component is disposed on, or at least partially embedded in, a flexible base.

5. The apparatus of claim 1, wherein the buffer structure has a disk shape with a central axis and an outer edge surface defining an outer diameter of the disk shape.

6. The apparatus of claim 5, wherein the buffer structure is positioned relative to the device component such that the central axis of the buffer structure is horizontally offset from the junction region in a first direction and such that the outer edge surface of the buffer structure is horizontally offset from the junction region in a second opposing direction.

7. The apparatus of claim 1, wherein the conductive stretchable interconnect is embedded in a polymer, and wherein the encapsulant encapsulates the polymer.

8. The apparatus of claim 7, wherein the polymer is a polyimide.

9. The apparatus of claim 1, wherein the buffer structure is formed from a polymer.

10. The apparatus of claim 9, wherein the polymer is a polyimide.

11. The apparatus of claim 1, wherein the conductive stretchable interconnect comprises gold, copper, aluminum, stainless steel, silver, a doped semiconductor, a conductive polymer, or any combination thereof.

12. The apparatus of claim 1, wherein the encapsulant is an elastomer.

13. The apparatus of claim 1, wherein the device component is disposed on a flexible base.

14. The apparatus of claim 1, wherein the buffer structure is sized, shaped, and positioned to redistribute strain imparted on the apparatus away from the junction region.

15. The apparatus of claim 1, wherein the buffer structure is more rigid than the encapsulant.

16. The apparatus of claim 1, wherein the buffer structure is formed from a first material having a first value of Young'"'"'s modulus and the encapsulant is formed from a second material having a second value of Young'"'"'s modulus that is less than the first value of Young'"'"'s modulus.

17. The apparatus of claim 1, wherein the buffer structure is thicker than the conductive stretchable interconnect.

18. The apparatus of claim 1, wherein the first layer is in a first X-Y plane and the second layer is in a second X-Y plane, the first and second X-Y planes being spaced from each other along a Z-axis that is perpendicular to both of the first and second X-Y planes.

19. An apparatus comprising:

a device component;

a conductive stretchable interconnect electrically coupled with the device component at a junction region, the conductive stretchable interconnect being positioned in a first layer of the apparatus;

a first buffer structure positioned in a second layer of the apparatus that is spaced from the first layer of the apparatus, the first buffer structure being formed from a non-conductive material;

a second buffer structure positioned in a third layer of the apparatus that is spaced from the first and second layers of the apparatus, the second buffer structure being formed from a non-conductive material; and

an encapsulant encapsulating the device component and the junction region.

20. The apparatus of claim 19, wherein the first buffer structure has a first an annular shape with an inner edge surface defining an inner diameter of the first annular shape and an outer edge surface defining an outer diameter of the first annular shape, and wherein the second buffer structure has a second an annular shape with an inner edge surface defining an inner diameter of the second annular shape and an outer edge surface defining an outer diameter of the second annular shape.

21. The apparatus of claim 20, wherein the inner edge surfaces of the first and second buffer structures are horizontally offset from the junction region in a first direction, and wherein the outer edge surfaces of the first and second buffer structures are horizontally offset from the junction region in a second opposing direction.

22. The apparatus of claim 20, wherein the device component is disposed on, or at least partially embedded in, a flexible base.

23. The apparatus of claim 19, wherein the conductive stretchable interconnect is embedded in a polymer, and wherein the encapsulant encapsulates the polymer.

24. The apparatus of claim 19, wherein the first buffer structure or the second buffer structure is formed from a polymer.

25. The apparatus of claim 24, wherein the polymer is a polyimide.

26. The apparatus of claim 19, wherein the conductive stretchable interconnect comprises gold, copper, aluminum, stainless steel, silver, a doped semiconductor, a conductive polymer, or any combination thereof.

27. The apparatus of claim 19, wherein the encapsulant is an elastomer.

28. The apparatus of claim 19, wherein the first buffer structure is positioned in the second layer adjacent to a first side of the device component and the second buffer structure is positioned in the third layer adjacent to a second opposing side of the device component such that a central axis of the first buffer structure is concentric with a central axis of the second buffer structure.

29. The apparatus of claim 19, wherein the first buffer structure is positioned in the second layer adjacent to a first side of the device component and the second buffer structure is positioned in the third layer adjacent to a second opposing side of the device component such that a central axis of the first buffer structure is not coincident with a central axis of the second buffer structure.

30. The apparatus of claim 19, wherein the first and second buffer structures are sized, shaped, and positioned to redistribute strain imparted on the apparatus away from the junction region.

31. The apparatus of claim 19, wherein the first and second buffer structures are more rigid than the encapsulant.

32. The apparatus of claim 19, wherein the first and second buffer structures are formed from a first material having a first value of Young'"'"'s modulus and the encapsulant is formed from a second material having a second value of Young'"'"'s modulus that is less than the first value of Young'"'"'s modulus.

33. The apparatus of claim 19, wherein the first and second buffer structures are each thicker than the conductive stretchable interconnect.

34. The apparatus of claim 19, wherein the first layer is in a first X-Y plane, the second layer is in a second X-Y plane, and the third layer is in a third X-Y plane, the first, second, and third X-Y planes being spaced from each other along a Z-axis that is perpendicular to each of the first, second, and third X-Y planes.