Rigid/flex printed circuit board using angled prepreg

• US 5,997,983 A
• Filed: 05/30/1997
• Issued: 12/07/1999
• Est. Priority Date: 05/30/1997
• Status: Expired due to Fees

• Current Assignee: Teledyne Technologies Incorporated
• Original Assignee: Teledyne Instruments Incorporated (Teledyne Technologies Incorporated)
• Inventors: Keating, James E., Millette, Lee J., Jean, Sandra L., Larmouth, Robert S., Caron, A. Roland
• Primary Examiner(s): Jones, Deborah
• Assistant Examiner(s): LAM, CATHY FONG FONG
• Application Number:
  US08/865,888
• Time in Patent Office: 921 Days
• Field of Search: 442/378, 442/228, 442/232, 428/209, 428/901, 428/902, 428/105, 174/254
• US Class Current: 428/105
• CPC Class Codes: H05K 1/0366 reinforced, e.g. by fibres, fabrics H05K1/036 takes precedence
• 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 2201/0287 Unidirectional or parallel fibers
• CPC Class Codes: H05K 2201/09236 Parallel layout layout of balanced signal pairs H05K1/0245; superposed layout H05K2201/09672
• 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: Y10S 428/901 Printed circuit
• CPC Class Codes: Y10T 428/24058 including grain, strips, or filamentary elements in respective layers or components in angular relation
• CPC Class Codes: Y10T 428/24917 including metal layer
• CPC Class Codes: Y10T 442/3382 Including a free metal or alloy constituent
• CPC Class Codes: Y10T 442/3415 Preformed metallic film or foil or sheet [film or foil or sheet had structural integrity prior to association with the woven fabric]

Abstract

A rigid flex printed circuit board wherein the flex section of said board comprises a basestock composite with edges formed by laminating a conductive layer to a flexible insulator layer, the conductor layer containing at least one conductive pathway and the flexible insulator layer comprises fibers dispersed in a matrix polymer. The fibers are oriented with respect to the conductive pathway so that the conductive pathway is substantially non-aligned with said fibers, substantially along an entirety of the conductive pathway in the flex section so as to be flexible.

Claims

1. A rigid flex printed circuit board wherein the flex section of said board comprises

a basestock composite with edges, formed by laminating a conductive layer to a flexible insulator layer, said conductor layer containing at least one conductive pathway and said flexible insulator layer comprises woven fibers dispersed in a matrix polymer,

said woven fibers oriented with respect to said at least one conductive pathway so that said at least one conductive pathway is non-aligned with said woven fibers, substantially along an entirety of said at least one conductive pathway in said flex section, so as to be flexible.

2. The rigid flex printed circuit board of claim 1 wherein said woven fiber orientation is non-aligned to said edge of said basestock composite.

3. The rigid flex printed circuit board of claim 1 wherein said fiber orientation is about 45 degrees relative to one of said edges.

4. The rigid flex printed circuit board of claim 1, wherein said conductive layer comprises a thickness of about 9 micron to 1 micron copper sheet and said flexible insulator layer comprises fiberglass impregnated with a thermoset adhesive.

5. The rigid flex printed circuit of claim 4, wherein said thermoset adhesive is an epoxy resin.

6. The rigid flex printed circuit board of claim 1, wherein said at least one conductive pathway is formed by imaging and etching.

7. The rigid flex printed circuit board of claim 1, wherein said rigid flex circuit board has a greater number of cycles to failure in the flex section as measured by IPC-TM-650, over that of a comparison flex section, said comparison flex section formed by laminating a conductive layer to a flexible insulator layer containing a conductive pathway, and said flexible insulating layer comprising fibers dispersed in a matrix polymer, said fibers oriented with respect to said conductive pathway so that said conductive pathway is substantially aligned with said fibers substantially along an entirety of said conductive pathway in said comparison flex section.

8. The rigid flex printed circuit board of claim 1, wherein said flex section includes a flexible insulating covercoat selected from the group consisting of polyimide polymers, or flexible photoimageable solder masks.

9. The rigid flex printed circuit board of claim 1, wherein said flex section includes a covercoat, said covercoat containing fibers dispersed in a matrix polymer, wherein said fibers in said covercoat are oriented with respect to said at least one conductive pathway so that said at least one conductive pathway is substantially aligned with said fibers of the covercoat.

10. The rigid flex printed circuit board of claim 9 wherein said fiber orientation of said covercoat is non-aligned with respect to said edge of said covercoat.

11. The rigid flex printed circuit board of claim 8 wherein said fiber orientation is about 45 degrees relative to one of said edges.

12. The rigid flex printed circuit board of claim 9 wherein the woven fibers of the basestock are oriented with respect to said at least one conductive pathway so that said at least one conductive pathway is non-aligned with said woven fibers of said basestock substantially along an entirety of said at least one conductive pathway in said flex section.

13. The rigid flex printed circuit board of claim 9, wherein said rigid flex circuit hoard has a greater number of cycles to failure in the flex section as measured by IPC-TM-650, over that of a comparison flex section of a printed circuit board containing a conductive pathway, said comparison flex section containing a covercoat layer comprising fibers dispersed in a matrix polymer, wherein the fibers of the matrix polymer are substantially aligned along an entirety of said conductive pathway in said comparison flex section.

14. A rigid flex printed circuit board wherein the flex section of the board comprises a basestock composite, formed by laminating a conductive layer to an insulating layer comprising woven fibers dispersed in a matrix polymer, said conductive layer containing at least one conductive pathway, said flex section further containing a covercoat layer with edges, said covercoat layer comprising fibers dispersed in a matrix polymer, wherein the fibers of said covercoat layer are oriented with respect to said at least one conductive pathway so that said at least one conductive pathway is non-aligned with said fibers of the covercoat substantially along an entirety of said at least one conductive pathway in said flex section, so as to be flexible.