LEADFRAME PACKAGE FOR MEMS MICROPHONE ASSEMBLY

• US 20080157301A1
• Filed: 01/03/2007
• Published: 07/03/2008
• Est. Priority Date: 01/03/2007
• Status: Active Grant

• Current Assignee: Stats Chippac Incorporated (JCET Group Co., Ltd.)
• Original Assignee: Stats Chippac Incorporated (JCET Group Co., Ltd.)
• Inventors: Chow, Seng Guan, Ramakrishna, Kambhampati
• Granted Patent: US 7,550,828 B2
• Time in Patent Office: Days
• US Class Current: 257/676
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 7/0061 suitable for fluid transfer from the MEMS out of the package or vice versa, e.g. transfer of liquid, gas, sound
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• 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 2924/01046 Palladium [Pd]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/1461 MEMS
• CPC Class Codes: H01L 2924/19041 being a capacitor
• CPC Class Codes: H04R 1/04 Structural association of microphone with electric circuitry therefor in deaf-aid sets H04R25/00
• CPC Class Codes: H04R 1/2869 Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself
• CPC Class Codes: H04R 19/005 using semiconductor materials
• CPC Class Codes: H04R 31/006 : Interconnection of transducer parts of diaphragm and outer suspension by moulding H04R31/003

Abstract

A cavity semiconductor package has a pre-molded leadframe construction. The leadframe is formed by molding around a die pad, and plural terminal lands. The leadframe has a hole for an acoustic port, such that the package can be soldered on a back side of a printed circuit board and have air access to a sensor die in the package from a front side of the printed circuit board via the acoustic port. The leadframe may also have a hollow or concave recess that defines an acoustic cavity in conjunction with the sensor die or printed circuit board.

Claims

1. A cavity semiconductor package comprising:

a leadframe having a die pad, a plurality of terminal lands, and an outer frame portion formed with a molding material about the die pad and the terminal lands and leaving portions of the die pad and terminal lands exposed on a top surface and a bottom surface of the leadframe, and an acoustic opening extending through the leadframe permitting through-air transmission of acoustic energy into the cavity semiconductor package.

2. The cavity semiconductor package of claim 1 wherein the acoustic opening is through the die pad of the leadframe.

3. The cavity semiconductor package of claim 1 wherein the acoustic opening is through the outer frame portion of the leadframe.

4. The cavity semiconductor package of claim 1 wherein the acoustic opening is centrally located on the leadframe.

5. The cavity semiconductor package of claim 1 wherein the acoustic opening is located off-center on the leadframe.

6. The cavity semiconductor package of claim 1 wherein the leadframe has a metallic plated area on the bottom surface about the acoustic opening for the cavity semiconductor package to be soldered to a printed circuit board to thereby form an air-tight seal between the leadframe and the printed circuit board about the acoustic opening and an aligned hole in the printed circuit board.

7. The cavity semiconductor package of claim 6 wherein the leadframe has an unplated area on the bottom surface immediately around the acoustic opening for helping to avoid solder contamination and obstruction of the acoustic opening when the cavity semiconductor package is soldered at the metallic plated area to the printed circuit board.

8. The cavity semiconductor package of claim 1 wherein the die pad has an inwardly hollowed surface adjoining the acoustic opening for defining an acoustic cavity.

9. The cavity semiconductor package of claim 8 wherein the inwardly hollowed surface is on top of the die pad, and defines an acoustic cavity between the leadframe and a semiconductor die with the semiconductor die mounted within the cavity semiconductor package on top of the die pad of the leadframe.

10. The cavity semiconductor package of claim 8 wherein the inwardly hollowed surface is on bottom of the die pad, and defines an acoustic cavity between the leadframe and a printed circuit board with the cavity semiconductor package mounted on the printed circuit board.

11. The cavity semiconductor package of claim 1, further comprising:

a conductive lid attached to the leadframe for enclosing a semiconductor die between the conductive lid and the leadframe with the semiconductor die mounted to the die pad on the leadframe.

12. The cavity semiconductor package of claim 11, wherein the conductive lid has a further acoustic opening in the conductive lid permitting through-air transmission of acoustic energy to the cavity semiconductor package.

23. The method of claim 1, further comprising:

attaching a conductive lid to the leadframe for enclosing a semiconductor die mounted to the die pad on the leadframe.

24. The method of claim 23, wherein the conductive lid has a further acoustic opening in the conductive lid permitting travel of acoustic energy into the cavity semiconductor package.

13. A method of manufacturing a cavity semiconductor package, comprising:

providing a die pad and a plurality of terminal lands;

molding a material about the die pad and the terminal lands to form an outer frame portion of a leadframe having a top surface and a bottom surface and leaving portions of the die pad and terminal lands exposed on the top surface and the bottom surface of the leadframe; and

providing a hole through the leadframe from the top surface to the bottom surface to serve as an acoustic opening permitting sound travel to a semiconductor die mounted on the die pad to be packaged in the cavity semiconductor package.

14. The method of claim 13 wherein the hole is through the die pad of the leadframe.

15. The method of claim 13 wherein the hole is through the outer frame portion of the leadframe.

16. The method of claim 13 wherein the hole is centrally located on the leadframe.

17. The method of claim 13 wherein the hole is located off-center on the leadframe.

18. The method of claim 13, further comprising:

plating an area with a metal on the bottom surface of the leadframe about the hole for soldering the cavity semiconductor package to a printed circuit board to thereby form an air-tight seal between the leadframe and the printed circuit board about the acoustic opening and an aligned hole in the printed circuit board.

19. The method of claim 18, further comprising:

leaving an unplated area on the bottom surface immediately adjacent the hole for helping to avoid solder contamination and obstruction of the acoustic opening when the cavity semiconductor package is soldered at the metallic plated area to the printed circuit board.

20. The method of claim 13 wherein the die pad has an inwardly hollowed surface adjoining the acoustic opening for defining an acoustic cavity.

21. The method of claim 20 wherein the inwardly hollowed surface is on top of the die pad, and defines an acoustic cavity between the leadframe and a semiconductor die with the semiconductor die mounted within the cavity semiconductor package on top of the die pad of the leadframe.

22. The method of claim 20 wherein the inwardly hollowed surface is on bottom of the die pad, and defines an acoustic cavity between the leadframe and a printed circuit board with the cavity semiconductor package mounted on the printed circuit board.