FOLDED LEADFRAME MULTIPLE DIE PACKAGE

• US 20090194855A1
• Filed: 02/05/2008
• Published: 08/06/2009
• Est. Priority Date: 02/05/2008
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Fairchild Semiconductor Corporation (ON Semiconductor Corporation)
• Inventors: Yang, Hua, Maldo, Tiburcio A., Liu, Yong
• Granted Patent: US 8,198,710 B2
• Time in Patent Office: Days
• US Class Current: 257/666
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 23/49551 characterised by bent parts
• CPC Class Codes: H01L 23/49562 for devices being provided for in H01L29/00
• CPC Class Codes: H01L 23/49575 Assemblies of semiconductor devices on lead frames
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 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: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/207 Diameter ranges
• CPC Class Codes: H01L 2924/30107 Inductance

Abstract

A multiple die package includes a folded leadframe for interconnecting at least two die attached to another leadframe. In a synchronous voltage regulator the folded leadframe, which is formed from a single piece of material, connects the high side switching device with the low side switching device to provide a low resistance, low inductance connection between the two devices.

Claims

1. A multiple die package comprising:

a) a folded leadframe having two plates connected by a belt member, a surface of each of said plates having the largest area being parallel with each other;

b) a second leadframe positioned between said plates; and

c) first and second die, each attached to said second leadframe and to one of said plates.

2. The multiple die package of claim 1 wherein said folded leadframe includes another plate connected by another belt member such that said three plates and said two belts are in the shape of a “

Z”

viewed from one side of said folded leadframe.

3. The multiple die package of claim 1 wherein each of said plates have substantially the same physical dimensions.

4. The multiple die package of claim 1 wherein said plates overlap such that each of the side surfaces of each of said plates lies in the same plane as a side surface of the other plane.

5. The multiple die package of claim 1 wherein each of said plates has a die attached to it.

6. The multiple die package of claim 5 wherein one of said attachments is a die bond attachment.

7. The multiple die package of claim 5 wherein one of said attachments is to a solder bump on said die.

8. The multiple die package of claim 1 wherein each of said first and second die are attached to opposite sides of said second leadframe.

9. The multiple die package of claim 1 wherein said two plates and said belt member are an integral element.

10. The multiple die package of claim 1 further including a metal tab integral with one of said plates.

11. The multiple die package of claim 10 wherein said metal tab has a mounting hole.

12. The multiple die package of claim 1 wherein said another leadframe includes a plurality of external leads.

13. The multiple die package of claim 12 wherein the longitudinal axis of one of said plates is parallel with the longitudinal axis of said external leads.

14. The multiple die package of claim 1 wherein said plates and said another leadframe have alignment holes.

15. The multiple die package of claim 1 wherein said package is at least partially encapsulated with encapsulating material.

16. The multiple die package of claim 15 wherein at least one surface of at least one of the plates is not encapsulated.

17. The multiple die package of claim 15 wherein at least one of said plates has a tab attached to one of said external leads.

18. The multiple die package of claim 1 further including a double bonded ceramic (DBC) plate attached to one of said plates.

19. The multiple die package of claim 18 wherein said side of said DBC plate not attached to one of said plates is not encapsulated.

20. The multiple die package of claim 1 further including two additional plates and two additional another leadframes with said another leadframes sandwiched between two of said plates, and die attached to opposite sides of each of said another leadframes and one of said plates.

21. A multiple die package for a synchronous voltage converter comprising:

a) a folded leadframe having two plates connected by a belt member, a surface of each of said plates having the largest area being parallel with each other;

b) a second leadframe positioned between said plates; and

c) a high side die and a low side die, each attached to said second leadframe and to one of said plates.

22. The multiple die package of claim 21 wherein said low side die is die bonded to said second leadframe.

23. The multiple die package of claim 21 wherein each of the corresponding top bottom and side surfaces of said low side die and said high side die are not in the same plane.

24. The multiple die package of claim 21 wherein said high side die and said low side die are parallel with each other and located in different planes.

25. The multiple die package of claim 21 wherein corresponding sides of said low side die and said high side die are located in the same plane.

26. The multiple die package of claim 21 wherein said package is at least partially encapsulated with encapsulating material.

27. The multiple die package of claim 26 wherein said multiple die package has external leads and at least one surface of one of said folded leadframe, said high side die, and said low side die is not encapsulated and provides as electrical connection to said synchronous voltage converter not present in said external leads.

28. A multiple die package for a synchronous voltage converter comprising:

a) a folded leadframe having two plates connected by a belt member, a surface of each of said plates having the largest area being parallel with each other;

b) a second leadframe positioned between said plates;

c) a high side die and a low side die, each attached to said second leadframe and to one of said plates; and

d) a driver integrated circuit (IC) connected to said high side die and said low side die.

29. The multiple die package of claim 28 wherein said low side die is die bonded to said second leadframe.

30. The multiple die package of claim 28 wherein each of the corresponding top bottom and side surfaces of said low side die and said high side die are not in the same plane.

31. The multiple die package of claim 28 wherein corresponding sides of said low side die and said high side die are located in the same plane.

32. The multiple die package of claim 28 wherein said package is at least partially encapsulated with encapsulating material.

33. The multiple die package of claim 32 wherein said multiple die package has external leads and at least one surface of one of said folded leadframe, said high side die, and said low side die is not encapsulated and provides an electrical connection to said synchronous voltage converter not present in said external leads.

34. A method for forming a multiple die package comprising the steps of:

a) attaching a first and second die to opposite sides of a first leadframe;

b) forming a folded leadframe having parallel plates joined by a belt; and

c) placing said first leadframe between said plates and attaching said first and second die to said plates.

35. The method of claim 34 wherein said folded leadframe formed from a flat blank that is folded to form said parallel plates and belt.

36. The method of claim 35 wherein said belt is thinner than said plates.

37. The method of claim 34 wherein said parallel plates are congruent.

38. The method of claim 34 wherein said parallel plates are not congruent.

39. The method of claim 34 wherein said folded leadframe has four parallel plates, and further comprising attaching third and fourth die to opposite sides of a second leadframe, attaching fifth and sixth die to opposite sites of a third leadframe, and placing each of said second and third leadframes between two of said parallel plates, and attaching each of said third, fourth, fifth, and sixth die to one of said parallel plates.

40. A method for forming a multiple die package for a synchronous voltage converter comprising the steps of:

a) attaching a high side and low side die to opposite sides of a first leadframe;

b) forming a folded leadframe having parallel plates joined by a belt; and

c) placing said first leadframe between said plates and attaching said low side and high side die to said plates.

41. The method of claim 40 wherein said folded leadframe formed from a flat blank that is folded to form the parallel plates and belt.

42. The method of claim 41 wherein said belt is thinner than said plates.

43. The method of claim 44 wherein said parallel plates are congruent.

44. The method of claim 40 wherein said parallel plates are not congruent.

45. The method of claim 40 further including the step of partially encapsulating said package with an encapsulation material.

46. The method of claim 45 wherein said multiple die package has external leads and at least one surface of one of said folded leadframe, said high side die, and said low side die is not encapsulated and provides an electrical connection to said synchronous voltage converter not present in said external leads.

47. A method for forming a multiple die package for a synchronous voltage converter comprising the steps of:

a) attaching a high side and low side die to opposite sides of a first leadframe;

b) forming a folded leadframe having parallel plates joined by a belt;

c) placing said first leadframe between said plates and attaching said low side and high side die to said plates; and

d) attaching an integrated circuit (IC) to said first leadframe, and wire bonding said IC to said first leadframe.

48. The method of claim 47 wherein said folded leadframe formed from a flat blank that is folded to form the parallel plates and belt.

49. The method of claim 48 wherein said belt is thinner than said plates.

50. The method of claim 47 wherein said parallel plates are congruent.

51. The method of claim 47 wherein said parallel plates are not congruent.

52. The method of claim 47 further including the step of partially encapsulating said package with an encapsulation material.

53. The method of claim 52 wherein said multiple die package has external leads and at least one surface of one of said folded leadframe, said high side die, and said low side die is not encapsulated and provides an electrical connection to said synchronous voltage converter not present in said external leads.