Packaging for silicon sensors

• US 6,028,773 A
• Filed: 11/17/1997
• Issued: 02/22/2000
• Est. Priority Date: 11/14/1997
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Inventors: Hundt, Michael J.
• Primary Examiner(s): Picard, Leo P.
• Assistant Examiner(s): FOSTER, DAVID A
• Application Number:
  US08/971,636
• Time in Patent Office: 827 Days
• Field of Search: 361/760, 361/748, 361/764, 361/765, 361/772, 361/773, 361/820, 174/250, 174/259, 174/260, 174/52.1, 174/52.4, 257/684, 257/782, 257/783, 257/735, 257/690, 257/692, 257/694, 257/784, 257/778, 250/208.1
• US Class Current: 361/760
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/49175 Parallel arrangements
• 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

Abstract

An integrated circuit package for direct mounting of an integrated circuit die to a printed circuit board is disclosed. The integrated circuit die includes a silicon sensor that detects changes in external variables, such as providing an image of a human fingerprint. The integrated circuit die has wire bond pads formed along only one side thereof to provide maximum exposure of the top surface area of the silicon sensor. The die is affixed to the printed circuit board and an adhesive surface coating, such as epoxy, is applied to the die and the printed circuit board for sealing the die thereto. The adhesive surface coating is formed from a first bead applied to the printed circuit board to cover at least the ends of the wires bonded to the board and a second bead applied to the first bead and the die to enclose the sides of the die and partially overlap the wire band pads and wires on top surface thereof.

Claims

1. A packaged integrated circuit, comprising:

a substrate;

an integrated circuit die positioned on said substrate, said integrated circuit die having a top surface and sides; and

an adhesive surface coating applied to said substrate and said sides of said integrated circuit die for sealing said integrated circuit die to said substrate such that a substantial portion of said top surface of said die is exposed.

2. The integrated circuit of claim 1 wherein said adhesive surface coating comprises a first bead of adhesive surface coating and a second bead of adhesive surface coating, said first and second beads extending at least partially around the circumference of said integrated circuit die.

3. The integrated circuit of claim 2 wherein said first bead of adhesive surface coating extends entirely around the circumference of said integrated circuit die.

4. The integrated circuit of claim 3 wherein said first bead is applied to said substrate and said integrated circuit die and said second bead is applied to said first bead and said integrated circuit die to extend at least partially around said integrated circuit die.

5. The integrated circuit of claim 3 wherein said first bead is applied to said substrate a predetermined distance from said integrated circuit die to form a space therebetween, and further wherein said second bead is applied in said space.

6. The integrated circuit of claim 5 wherein said second bead contacts said first bead and said integrated circuit die.

7. The integrated circuit of claim 1 wherein said coating partially overlaps said top surface of said integrated circuit die.

8. The integrated circuit of claim 6 wherein said first bead is formed of a first type of adhesive surface coating material and said second bead is formed of a second type of adhesive surface coating material.

9. The integrated circuit of claim 8 wherein said first type of adhesive surface material has a lower flow rate when heated than the heated flow rate of said second type of adhesive surface coating material.

10. The integrated circuit of claim 9 wherein said second bead extends entirely around the circumference of said integrated circuit die.

11. A packaged integrated circuit, comprising:

a printed circuit board having one or more electrically conductive traces formed thereon;

an integrated circuit die affixed to said printed circuit board, said integrated circuit die having a top surface and sides, and a plurality of wires having a first end electrically connected to said integrated circuit die and a second end electrically connected to said traces on said printed circuit board; and

an adhesive surface coating applied to said printed circuit board and said sides of said integrated circuit die to extend at least partially around the circumference of said integrated circuit die for sealing said integrated circuit die to said printed circuit board such that a substantial portion of the surface area of said top surface of said integrated circuit die is exposed.

12. The integrated circuit of claim 11 wherein said wires are electrically connected along only one side of said integrated circuit die.

13. The integrated circuit of claim 11 wherein said adhesive surface coating comprises a first bead of adhesive surface coating and a second bead of adhesive surface coating.

14. The integrated circuit of claim 13 wherein said first bead of adhesive surface coating extends entirely around the circumference of said integrated circuit die.

15. The integrated circuit of claim 14 wherein said first bead is applied to said printed circuit board and at least said sides of said integrated circuit die to cover at least said second end of said wires connected to said printed circuit board, and said second bead is applied to said first bead and said integrated circuit die to extend at least partially around said integrated circuit die and partially overlap said top surface to cover at least said first end of said wires connected to said integrated circuit die.

16. The integrated circuit of claim 13 wherein said first bead is applied to said printed circuit board a predetermined distance from said integrated circuit die to form a space between said first bead and said integrated circuit die, and further wherein said second bead is applied in said space.

17. The integrated circuit of claim 16 wherein said second bead contacts said first bead and at least said sides of said integrated circuit die.

18. The integrated circuit of claim 11 wherein said second bead partially overlaps said top surface of said integrated circuit die.

19. The integrated circuit of claim 17 wherein said first bead is formed of a first type of adhesive surface coating material and said second bead is formed of a second type of adhesive surface coating material.

20. The integrated circuit of claim 19 wherein said first type of adhesive surface material has a lower flow rate when heated than the heated flow rate of said second type of adhesive surface coating material.

21. The integrated circuit of claim 20 wherein said second bead extends entirely around the circumference of said integrated circuit die.

22. A method for packaging an integrated circuit, comprising the steps of:

positioning an integrated circuit die on a substrate;

applying an adhesive surface coating to the substrate and a circumferential edge of the integrated circuit die; and

heating the substrate and integrated circuit die to cause the adhesive surface coating to flow onto the substrate and the integrated circuit die and harden such that the integrated circuit die is sealed to the substrate and a substantial portion of the top surface of the integrated circuit die is exposed.

23. The method of claim 22 wherein said step of applying an adhesive surface coating comprises applying a first bead of adhesive surface coating at least partially around the circumference of the integrated circuit die and applying a second bead of an adhesive surface coating at least partially around the circumference of the integrated circuit die.

24. The method of claim 23 wherein the first bead is applied to the substrate and the integrated circuit die, and the second bead is applied to the integrated circuit die and the first bead.

25. The method of claim 24 wherein the first bead is applied around the entire circumference of the integrated circuit die.

26. The method of claim 23 wherein the first bead is applied to the substrate and positioned a predetermined distance from the integrated circuit die to form a space between the first bead and the integrated circuit die, and the second bead is applied to fill in the space.

27. The method of claim 26 wherein the second bead fills the space between the first bead and the integrated circuit die and flows partially onto the top surface of the integrated surface die when heated.

28. The method of claim 27 wherein the second bead extends around the entire circumference of the integrated circuit die.

29. A method for packaging an integrated circuit, comprising the steps of:

mounting an integrated circuit die having sides and top and bottom surfaces on a printed circuit board having electrically conductive traces formed thereon;

bonding a first end of electrically conductive wires to the integrated circuit die and a second end of the wires to the electrically conductive traces on the printed circuit board;

applying an adhesive surface coating to the printed circuit board and the sides of the integrated circuit die to cover at least the wires; and

heating the printed circuit board and the integrated circuit die to cause the adhesive surface coating to flow onto the printed circuit board and the integrated circuit die and then harden such that the integrated circuit die is sealed to the printed circuit board and a substantial portion of the top surface of the integrated circuit die is exposed.

30. The method of claim 29 wherein the wires are attached to only a single side of the integrated circuit die.

31. The method of claim 29 wherein said step of applying an adhesive surface coating comprises applying a first bead of adhesive surface coating at least partially around the circumference of the integrated circuit die and applying a second bead of an adhesive surface coating at least partially around the circumference of the integrated circuit die.

32. The method of claim 31 wherein the first bead is applied to the printed circuit board and the integrated circuit die to cover at least the second ends of the wires, and the second bead is applied to the integrated circuit die to cover at least the first ends of the wires.

33. The method of claim 32 wherein the first bead is applied around the entire circumference of the integrated circuit die.

34. The method of claim 33 wherein the first bead is applied to the printed circuit board and positioned a predetermined distance from the integrated circuit die to form a space between the first bead and the integrated circuit die, and the second bead is applied in the space formed between the first bead and the integrated circuit die.

35. The method of claim 34 wherein the second bead fills the space between the first bead and the integrated circuit die and flows partially onto the top surface of the integrated surface die when heated.

36. The method of claim 35 wherein the second bead extends around the entire circumference of the integrated circuit die.

37. The method of claim 33, wherein the second bead is positioned a predetermined distance from the first bead to create a spare there between.

38. The method of claim 37 wherein a third bead is applied in the space between the second bead and the first bead.

39. The method of claim 38 wherein said third bead overlaps said first bead and extends around the entire circumference of the integrated circuit die.

40. A packaged integrated circuit, comprising:

a substrate;

an integrated circuit die positioned on said substrate, said integrated circuit die having a top surface and sides; and

an adhesive surface coating applied to said substrate and said sides of said integrated circuit die for sealing said integrated circuit die to said substrate such that a substantial portion of said top surface of said die is exposed, said adhesive surface coating comprising a first bead of adhesive surface coating applied to said substrate a predetermined distance from said integrated circuit and at least partially around the circumference of said integrated circuit die to form a space therebetween, and a second bead of adhesive surface coating applied in said space to contact said first bead and said integrated circuit die and to extend at least partially around the circumference of said integrated circuit die.

41. The packaged integrated circuit of claim 40 wherein said second bead partially overlaps said top surface of said integrated circuit die.

42. A packaged integrated circuit, comprising:

a substrate;

an integrated circuit die positioned on said substrate, said integrated circuit die having a top surface and sides; and

an adhesive surface coating applied to said substrate and said sides of said integrated circuit die for sealing said integrated circuit die to said substrate such that a substantial portion of said top surface of said die is exposed, said adhesive surface coating comprising a first bead of adhesive surface coating applied to said substrate and at least partially around the circumference of said integrated circuit die and a second bead of adhesive surface coating applied to contact said first bead and said integrated circuit die and to extend at least partially around the circumference of said integrated circuit die, said first bead formed of a first type of adhesive surface coating material and said second bead formed of a second type of adhesive surface coating material.

43. The packaged integrated circuit of claim 42 wherein said first type of adhesive surface coating material has a lower flow rate when heated than the heated flow rate of said second type of adhesive surface coating material.

44. The packaged integrated circuit of claim 42 wherein said second bead extends entirely around the circumference of said integrated circuit die.

45. A packaged integrated circuit, comprising:

a printed circuit board having one or more electrically conductive traces formed thereon;

an integrated circuit die affixed to said printed circuit board, said integrated circuit die having a top surface and sides, and a plurality of wires having a first end electrically connected to said integrated circuit die and a second end electrically connected to said traces on said printed circuit board; and

an adhesive surface coating applied to said printed circuit board and said integrated circuit die for sealing said integrated die to said printed circuit board such that a substantial portion of the surface area of said top surface of said integrated circuit die is exposed, said adhesive surface coating comprising a first bead of adhesive surface coating applied to said printed circuit board a predetermined distance from said integrated circuit die to form a space between said first bead and said integrated circuit die, and a second bead of adhesive surface coating applied in said space and in contact with said first bead and said sides of said integrated circuit die.

46. The packaged integrated circuit of claim 45 wherein said second bead partially overlaps said top surface of said integrated circuit die.

47. A packaged integrated circuit comprising:

a printed circuit board having one or more electrically conductive traces formed thereon;

an integrated circuit die affixed to said printed circuit board, said integrated circuit die having a top surface and sides, and a plurality of wires having a first end electrically connected to said integrated circuit die and a second end electrically connected to said traces on said printed circuit board; and

an adhesive surface coating applied to said printed circuit board and said integrated circuit die for sealing said integrated circuit die to said printed circuit board such that a substantial portion of the surface area of said top surface of said integrated die is exposed, said adhesive surface coating comprising a first bead of adhesive surface coating formed of a first type of adhesive surface coating material and applied to said printed circuit board, and a second bead of adhesive surface coating formed of a second type of adhesive surface coating material and applied in contact with said first bead and said sides of said integrated circuit die.

48. The packaged integrated circuit die of claim 47 wherein said first type of adhesive surface material has a lower flow rate when heated than the heated flow rate of said second type of adhesive surface coating material.

49. The packaged integrated circuit die of claim 47 wherein said second bead extends entirely around the circumference of said integrated circuit die.