Circuit card with flexible connection for memory module with heat spreader

• US 7,442,050 B1
• Filed: 08/28/2006
• Issued: 10/28/2008
• Est. Priority Date: 08/29/2005
• Status: Active Grant

• Current Assignee: Netlist, Inc.
• Original Assignee: Netlist, Inc.
• Inventors: Bhakta, Jayesh R., Chen, Chi She, Flaig, Richard E., Yu, Enchao
• Primary Examiner(s): Dinh; Phuong K
• Application Number:
  US11/511,523
• Time in Patent Office: 792 Days
• Field of Search: 439/70, 439/71, 361780-785, 361/803
• US Class Current: 439/71
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2924/00011 Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H05K 1/0203 Cooling of mounted components H05K1/0272 takes precedence
• CPC Class Codes: H05K 1/141 One or more single auxiliary printed circuits mounted on a main printed circuit, e.g. modules, adapters H05K1/142 and H05K1/147 take precedence
• 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 2201/10159 Memory
• CPC Class Codes: H05K 2201/1056 Metal over component, i.e. metal plate over component mounted on or embedded in PCB
• CPC Class Codes: H05K 2203/1572 Processing both sides of a PCB by the same process; Providing a similar arrangement of components on both sides; Making interlayer connections from two sides
• 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 circuit card includes a rigid portion having a first plurality of contacts configured to be in electrical communication with a plurality of memory devices. The circuit card further includes a flexible connector coupled to the rigid portion. The flexible connector has a first side and a second side. The flexible connector comprises a dielectric layer, a second plurality of contacts configured to be in electrical communication with a substrate, and a plurality of electrical conduits on the first side of the flexible connector and extending from the rigid portion to the second plurality of contacts. The plurality of electrical conduits is in electrical communication with one or more contacts of the first plurality of contacts and with the second plurality of contacts. The flexible connector further includes an electrically conductive layer on the second side of the flexible connector. The electrically conductive layer is superposed with the plurality of electrical conduits with the dielectric layer therebetween. The electrically conductive layer does not cover one or more portions of the second side of the flexible connector, thereby providing improved flexibility of the flexible connector.

Claims

1. A circuit card comprising:

a rigid portion having a first plurality of contacts configured to be in electrical communication with a plurality of memory devices; and

a flexible connector coupled to the rigid portion, the flexible connector having a first side and a second side, the flexible connector comprising;

a dielectric layer;

a second plurality of contacts configured to be in electrical communication with a substrate;

a plurality of electrical conduits on the first side of the flexible connector and extending from the rigid portion to the second plurality of contacts, the plurality of electrical conduits in electrical communication with one or more contacts of the first plurality of contacts and with the second plurality of contacts; and

an electrically conductive layer on the second side of the flexible connector, the electrically conductive layer superposed with the plurality of electrical conduits with the dielectric layer therebetween, wherein the electrically conductive layer does not cover one or more portions of the second side of the flexible connector, thereby providing improved flexibility of the flexible connector.

2. The circuit card of claim 1, wherein the rigid portion comprises a printed-circuit board.

3. The circuit card of claim 2, wherein the printed-circuit board comprises FR4 material.

4. The circuit card of claim 2, wherein the printed-circuit board is an eight-layer printed-circuit board.

5. The circuit card of claim 2, wherein the rigid portion further comprises a portion of the dielectric layer, a portion of the plurality of electrical conduits, and a portion of the electrically conductive layer.

6. The circuit card of claim 5, wherein the rigid portion comprises two rigid printed-circuit boards with the portion of the dielectric layer, the portion of the plurality of electrical conduits, and the portion of the electrically conductive layer sandwiched therebetween.

7. The circuit card of claim 1, wherein the first plurality of contacts comprises a ball-grid array.

8. The circuit card of claim 1, wherein the dielectric layer comprises a polymer material.

9. The circuit card of claim 1, wherein the electrically conductive layer comprises a plurality of metal lines in a cross-hatched pattern which define the portions therebetween which are not covered by the electrically conductive layer.

10. The circuit card of claim 1, wherein the electrically conductive layer comprises a plurality of metal traces that are superposed and generally parallel with the plurality of electrical conduits with the dielectric layer therebetween, the metal traces defining regions therebetween in which the electrically conductive layer does not cover the portion of the second side of the flexible connector.

11. The circuit card of claim 1, wherein the electrically conductive layer is a ground plane.

12. The circuit card of claim 1, wherein the electrically conductive layer is a power plane.

13. The circuit card of claim 1, wherein each contact of the second plurality of contacts comprises a hole extending from the first side of the flexible connector to the second side of the flexible connector.

14. The circuit card of claim 1, wherein each electrical conduit has a tapered section connected to a corresponding one of the contacts of the second plurality of contacts and an elongate section extending along a length of the first side of the flexible connector from the rigid portion to the tapered section.

15. A memory module comprising:

a main printed-circuit board (PCB) having a first side and a second side, the main PCB comprising a plurality of edge connectors configured to be in electrical communication with corresponding socket connectors of a computer system, the main PCB further comprising a first plurality of contacts in electrical communication with the plurality of edge connectors; and

a first daughter circuit card positioned on the first side of the main PCB and oriented generally parallel to the main PCB, the first daughter circuit card comprising a rigid portion and a plurality of memory devices mounted thereto, the first daughter circuit card further comprising a flexible connector and a second plurality of contacts thereon, the second plurality of contacts in electrical communication with the first plurality of contacts, the flexible connector having a first side and a second side, the flexible connector comprising;

a dielectric layer;

a plurality of electrical conduits on the first side of the flexible connector, the plurality of electrical conduits in electrical communication with the plurality of memory devices and the second plurality of contacts; and

an electrically conductive layer on the second side of the flexible connector, the electrically conductive layer superposed with the plurality of electrical conduits with the dielectric layer therebetween, wherein the electrically conductive layer does not cover one or more portions of the second side of the flexible connector, thereby providing improved flexibility of the flexible connector.

16. The memory module of claim 15, wherein the flexible connector is bent by an angle greater than 90 degrees.

17. The memory module of claim 16, wherein the flexible connector is bent by an angle of about 180 degrees.

18. The memory module of claim 15, wherein the main PCB comprises a first thermally conductive layer on the first side of the main PCB, the first thermally conductive layer providing thermal communication between one or more memory devices of the first daughter circuit card and one or more edge connectors.

19. The memory module of claim 15, wherein the main PCB further comprises a third plurality of contacts in electrical communication with the plurality of edge connectors, the memory module further comprises a second daughter circuit card positioned on the second side of the main PCB and oriented generally parallel to the main PCB, the second daughter circuit card comprising a rigid portion and a plurality of memory devices mounted thereto, the second daughter circuit card further comprising a flexible connector and a fourth plurality of contacts thereon, the fourth plurality of contacts in electrical communication with the third plurality of contacts, wherein the second daughter circuit card is substantially identical to the first daughter circuit card.

20. The memory module of claim 19, wherein the main PCB comprises a first thermally conductive layer on the first side of the main PCB, the first thermally conductive layer providing thermal communication between one or more memory devices of the first daughter circuit card and one or more edge connectors, and wherein the main PCB comprises a second thermally conductive layer on the second side of the main PCB, the second thermally conductive layer providing thermal communication between one or more memory devices of the second daughter circuit card and one or more edge connectors.

21. The memory module of claim 15, wherein the first plurality of contacts and the second plurality of contacts are connected to one another by solder.

22. The memory module of claim 15, wherein the main PCB comprises electronic components mounted thereon.

23. The memory module of claim 15, wherein the main PCB comprises a plurality of memory devices mounted thereon.

24. The memory module of claim 23, wherein the plurality of memory devices of the main PCB are mounted on the first side of the main PCB.

25. The memory module of claim 24, further comprising a heat spreader in thermal communication with one or more memory devices of the main PCB and with one or more memory devices of the first daughter circuit card.

26. The memory module of claim 25, wherein at least a portion of the heat spreader is sandwiched between one or more memory devices of the main PCB and one or more memory devices of the first daughter circuit card.

27. The memory module of claim 15, further comprising a heat spreader in thermal communication with one or more memory devices of the first daughter circuit card.

28. A computer system comprising a memory module comprising:

a printed-circuit board (PCB) having a first side and a second side, the PCB comprising a plurality of edge connectors configured to be in electrical communication with corresponding socket connectors of a computer system, the PCB further comprising a first plurality of contacts in electrical communication with the plurality of edge connectors; and

a first daughter circuit card positioned on the first side of the PCB and oriented generally parallel to the PCB, the first daughter circuit card comprising a rigid portion and a plurality of memory devices mounted thereto, the first daughter circuit card further comprising a flexible connector and a second plurality of contacts thereon, the second plurality of contacts in electrical communication with the first plurality of contacts, the flexible connector having a first side and a second side, the flexible connector comprising;

a dielectric layer;

a plurality of electrical conduits on the first side of the flexible connector, the plurality of electrical conduits in electrical communication with the plurality of memory devices and the second plurality of contacts; and

an electrically conductive layer on the second side of the flexible connector, the electrically conductive layer superposed with the plurality of electrical conduits with the dielectric layer therebetween, wherein the electrically conductive layer does not cover one or more portions of the second side of the flexible connector, thereby providing improved flexibility of the flexible connector.

29. An electronic circuit module for a computer system, the module comprising:

a first printed-circuit board (PCB) having an edge connector, a first side, and a second side;

a first plurality of electrical components mounted on the first side of the first PCB, the first plurality of electrical components electrically coupled to the edge connector;

a second plurality of electrical components mounted on the second side of the second PCB, the second plurality of electrical components electrically coupled to the edge connector;

a second PCB having a first side facing towards the first PCB and a second side facing away from the first PCB;

a third plurality of electrical components mounted on the first side of the second PCB;

a fourth plurality of electrical components mounted on the second side of the second PCB;

at least one electrical conduit between the first PCB and the second PCB, the at least one electrical conduit electrically coupling the third plurality of electrical components to the edge connector and electrically coupling the fourth plurality of electrical components to the edge connector; and

a heat spreader comprising a thermally conductive material, the heat spreader comprising;

a first portion thermally coupled to the first plurality of electrical components;

a second portion thermally coupled to the second plurality of electrical components and to the third plurality of electrical components; and

a third portion thermally coupled to the fourth plurality of electrical components.

30. The electronic module of claim 29, wherein the electronic module is a memory module.

31. The electronic module of claim 29, wherein the first plurality of electrical components, the second plurality of electrical components, the third plurality of electrical components, and the fourth plurality of electrical components each comprise memory devices.

32. The electronic module of claim 29, further comprising a third PCB having a first side facing towards the first PCB and a second side facing away from the first PCB, a fifth plurality of electrical components mounted on the first side of the third PCB, and a sixth plurality of electrical components mounted on the second side of the third PCB, wherein the heat spreader further comprises a fourth portion, the first portion thermally coupled to the fifth plurality of electrical components, and the fourth portion is thermally coupled to the sixth plurality of electrical components.

33. The electronic module of claim 29, further comprising a thermally conductive layer between the portions of the heat spreader and the electrical components.

34. The electronic module of claim 29, wherein the electrical conduit comprises a flexible electrical conduit.

35. The electronic module of claim 29, wherein the electrical conduit comprises a spacer that supports the second PCB on the first PCB.

36. The electronic module of claim 29, wherein the heat spreader comprises a plurality of separable sections.