Methods and apparatus for Flip-Chip-On-Lead semiconductor package

• US 7,361,531 B2
• Filed: 11/01/2005
• Issued: 04/22/2008
• Est. Priority Date: 11/01/2005
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Sharma, Nirmal, Ararao, Virgil
• Primary Examiner(s): Geyer; Scott B.
• Application Number:
  US11/265,801
• Publication Number:
  US 20070099348A1
• Time in Patent Office: 903 Days
• Field of Search: 438/110, 438/111, 438/121, 438/123, 438/124, 438/127, 257/E21.499, 257/E21.502, 257/E21.506, 257/E21.507, 257/E21.509, 257/E21.51, 257/E23.031, 257/E23.039, 257/E23.047, 257/E23.052, 257/E23.054, 257/E23.116
• US Class Current: 438/111
• CPC Class Codes: H01L 2224/05001 Internal layers
• CPC Class Codes: H01L 2224/05022 the internal layer being at least partially embedded in the surface
• CPC Class Codes: H01L 2224/05024 the internal layer being disposed on a redistribution layer on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/05124 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05548 Bonding area integrally formed with a redistribution layer on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/10175 Flow barriers
• CPC Class Codes: H01L 2224/131 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 2224/16245 the item being metallic
• CPC Class Codes: H01L 2224/16257 the bump connector connecting to a bonding area disposed in a recess of the surface of the item
• CPC Class Codes: H01L 2224/16258 the bump connector connecting to a bonding area protruding from the surface of the item
• CPC Class Codes: H01L 2224/1626 the bump connector connecting between the body and an opposite side of the item with respect to the body
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/73204 the bump connector being embedded into the layer connector
• CPC Class Codes: H01L 2224/811 the bump connector being supplied to the parts to be connected in the bonding apparatus
• CPC Class Codes: H01L 2224/81192 wherein the bump connectors are disposed only on another item or body to be connected to the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/81815 Reflow soldering
• CPC Class Codes: H01L 2224/83192 wherein the layer connectors are disposed only on another item or body to be connected to the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/8385 using a polymer adhesive, e.g. an adhesive based on silicone, epoxy, polyimide, polyester
• CPC Class Codes: H01L 2224/92143 the second connecting process involving a bump connector
• CPC Class Codes: H01L 23/4951 : Chip-on-leads or leads-on-chip techniques, i.e. inner lead fingers being used as die pad
• CPC Class Codes: H01L 23/4952 : the additional leads being a bump or a wire
• CPC Class Codes: H01L 23/49548 : Cross section geometry H01L23/49562 takes precedence
• CPC Class Codes: H01L 24/16 : of an individual bump connector
• CPC Class Codes: H01L 24/81 : using a bump connector
• CPC Class Codes: H01L 24/83 : using a layer connector
• CPC Class Codes: H01L 24/92 : Specific sequence of method steps
• 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 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01022 : Titanium [Ti]
• CPC Class Codes: H01L 2924/01024 : Chromium [Cr]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01046 : Palladium [Pd]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01076 : Osmium [Os]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/07802 : not being an ohmic electrical conductor
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/1306 : Field-effect transistor [FET]
• 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

Abstract

Fabrication of a semiconductor package includes placing a conductive material on a protrusion from a leadframe to form a first assembly, forming a non-conductive mask about the protrusion, and placing a die on the first assembly, the die having an active area. Fabrication can further include reflowing the conductive material to form a second assembly such that a connection extends from the die active area, through the conductive material, to the protrusion. A semiconductor package includes a leadframe having a protrusion, a conductive material reflowed to the protrusion, and a die having an active area coupled to the protrusion by the reflowed solder.

Claims

1. A method, comprising:

placing a conductive material on a protrusion from a leadframe to form a first assembly;

forming a non-conductive mask about the protrusion;

placing a die on the first assembly, the die having an active area;

reflowing the conductive material to raise up the die to form a second assembly such that a connection extends from the die active area, through the conductive material, to the protrusion; and

surrounding the die with a material to form a third assembly.

2. The method according to claim 1, further including forming a depression in the mask.

3. The method according to claim 2, wherein the conductive material is placed in the depression, wherein the protrusion extends into the depression.

4. The method according to claim 3, wherein the protrusion is a pad pillar.

5. The method according to claim 1, further including filling gaps about the reflowed conductive material with an epoxy compound.

6. The method according to claim 1, further including forming an under bump metallization structure at the active area of the die.

7. The method according to claim 1, wherein the die rests on the conductive material prior to reflow of the conductive material.

8. The method according to claim 1, further including forming a redistribution layer on the die to form a connection point for the active area.

9. A semiconductor package formed according to claim 1.

10. A method, comprising:

placing a mask on a lead frame having a protrusion, the mask having a depression into which the protrusion extends;

placing solder paste in the depression to form a first assembly;

placing a die on the first assembly, the die having an active area;

reflowing the solder paste to raise up the die; and

securing the die to the leadframe such that the solder forms a connection between the protrusion and the active area of the die.

11. The method according to claim 10, further including preparing the active area of the die to provide an under bump metallization structure.

12. The method according to claim 10, further including molding a package to hold the wafer and leadframe.

13. The method according to claim 10, further including filling gaps adjacent the reflowed solder with epoxy.

14. The method according to claim 10, further including forming the protrusion from the leadframe.

15. The method according to claim 10, wherein the solder paste extends above the depression.

16. An article, comprising:

a leadframe having a protrusion;

a non-conductive mask having a depression into which the protrusion extends;

a conductive material reflowed to the protrusion;

a die having an active area coupled to the protrusion by the reflowed solder;

a material about the conductive material to secure the die to the leadframe; and

an under bump metallization structure on active area of the die.

17. The article according to claim 16, wherein the conductive material includes solder paste that raised up the die when reflowed.

18. A device, comprising:

a semiconductor package, including;

a leadframe having a protrusion;

a non-conductive mask having a depression into which the protrusion extends;

a conductive material reflowed to the protrusion;

a die having an active area coupled to the protrusion by the reflowed solder;

a material about the conductive material to secure the die to the leadframe; and

an under bump metallization structure on active area of the die.

19. The device according to claim 18, wherein the semiconductor package does not have a wafer bump.