Surface mountable flexible interconnect

• US 5,928,001 A
• Filed: 09/08/1997
• Issued: 07/27/1999
• Est. Priority Date: 09/08/1997
• Status: Expired due to Term

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Potter, Scott, Lall, Pradeep, Gillette, Joseph G.
• Primary Examiner(s): Bradley, Paula
• Assistant Examiner(s): Davis, Katrina
• Application Number:
  US08/925,157
• Time in Patent Office: 687 Days
• Field of Search: 439/495, 439/496, 439/67
• US Class Current: 439/67
• CPC Class Codes: H01R 12/62 connecting to rigid printed circuits or like structures
• CPC Class Codes: H05K 1/118 specially for flexible printed circuits, e.g. using folded portions

Abstract

A surface mountable flexible interconnect (100) for connecting two electronic subassemblies is constructed from a flexible film substrate (110). Conductive metal runners (120) run along the bottom surface (114) of the substrate and connect an array of solder pads (122), each having an attached solder bump (123), to a second terminal portion (124) located at the second end of the substrate. A rigid sheet of printed circuit board material (130), attached to the top surface of the substrate using a strong adhesive (142), lies directly above the array of solder pads and acts as stress relief mechanism. A slightly tacky temporary adhesive (140) is used to attach the second end of the substrate to the topside (132) of the rigid sheet.

Claims

1. A surface mountable flexible interconnect structure, comprising:

a flexible film having upper and lower opposing surfaces, first and second ends, and a plurality of electrically conductive runners formed on the lower surface, each runner having a first and a second terminal portion, the first terminal portion comprising an interconnection pad having a solder bump affixed thereto;

a rigid member fixedly attached to the flexible film upper surface proximate to the first end; and

the second end of the flexible film folded back toward the first end and removably attached to the upper surface of the rigid member by a low-tack pressure sensitive adhesive, such that the second end may be subseguently detached from the rigid member.

2. The flexible interconnect structure as described in claim 1, wherein said flexible film is polyester or polyimide.

3. The flexible interconnect structure as described in claim 1, wherein said rigid member is injection molded directly to the flexible film upper surface.

4. The flexible interconnect structure as described in claim 1, wherein said rigid member is a laminated sheet fixedly attached to the flexible film upper surface by means of a high-tack pressure sensitive adhesive disposed between said laminated sheet and said flexible film.

5. The flexible interconnect structure as described in claim 1, wherein the electrically conductive runners are copper or graphite-based conductive ink.

6. The flexible interconnect structure as described in claim 1, wherein the second terminal portion comprises a pad, a finger, a pin, or a conductive adhesive.

7. A surface mountable flexible interconnect structure, comprising:

a flexible film having upper and lower opposing surfaces, first and second ends, and a plurality of electrically conductive runners formed on the lower surface, each runner having a first and a second terminal portion, the first terminal portion comprising an interconnection pad having an electrically conductive bump affixed thereto; and

a rigid member fixedly attached to the flexible film upper surface proximate to the first end, wherein

the second end is inwardly-rolled toward the flexible film upper surface and a resulting rolled portion of the flexible film is attached to an upper surface of the rigid member by means of a low-tack pressure sensitive adhesive.

8. The flexible interconnect structure as described in claim 7, further comprising a cover for containing the rolled portion of the flexible film, the cover is attached to the rigid member upper surface by means of low-tack pressure sensitive adhesive.

9. The flexible interconnect structure as described in claim 7, further comprising low-tack pressure sensitive adhesive partially disposed between interfacing surfaces of the rolled portion of the flexible film.

10. The flexible interconnect structure as described in claim 7, wherein said rigid member has tab portions extending beyond the width of the rolled portion of the flexible film.

11. The flexible interconnect structure as described in claim 7, wherein the flexible film is polyester or polyimide.

12. The flexible interconnect structure as described in claim 7, wherein the rigid member is injection molded directly to the flexible film upper surface.

13. The flexible interconnect structure as described in claim 7, wherein said rigid member is a laminated sheet fixedly attached to the flexible film upper surface by means of a high-tack pressure sensitive adhesive disposed between the laminated sheet and the flexible film.

14. The flexible interconnect structure as described in claim 7, wherein said electrically conductive bump is a solder bump.

15. The flexible interconnect structure as described in claim 7, wherein the electrically conductive runners are copper or graphite-based conductive ink.

16. The flexible interconnect structure as described in claim 7, wherein the second terminal portion comprises a pad, a finger, a pin, or a conductive adhesive.

17. A surface mountable flexible interconnect structure, comprising:

a flexible film having upper and lower opposing surfaces, first and second ends, and a plurality of electrically conductive runners formed on the lower surface, each runner having a first and a second terminal portion, the first terminal portion comprising a solder pad having a solder ball affixed thereto;

a rigid member having upper and lower surfaces, the rigid member lower surface fixedly attached to a portion of the flexible film upper surface proximate to the first end by means of a high-tack pressure sensitive adhesive; and

a low-tack pressure sensitive adhesive temporarily attaching a portion of the flexible film upper surface proximate to the second end to the rigid member lower surface, such that said portion of the flexible film upper surface proximate to the second end may be subsequently detached from the rigid member.