Methods and apparatus for multi-stage molding of integrated circuit package

• US 7,816,772 B2
• Filed: 03/29/2007
• Issued: 10/19/2010
• Est. Priority Date: 03/29/2007
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Taylor, William P., Engel, Raymond W., Sharma, Nirmal
• Primary Examiner(s): Parker; Kenneth A.
• Assistant Examiner(s): NGUYEN, JOSEPH H
• Application Number:
  US11/693,183
• Publication Number:
  US 20080237818A1
• Time in Patent Office: 1,300 Days
• Field of Search: 257/676, 257/692, 257/684, 257/701, 257/685, 324/252, 361/813
• US Class Current: 257/676
• CPC Class Codes: G01D 11/245 Housings for sensors
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: H01L 21/56 Encapsulations, e.g. encapsulation layers, coatings
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• 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 2924/00014 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

Methods and apparatus for providing an integrated circuit using a multi-stage molding process to protect wirebonds. In one embodiment, a method includes attaching a die to a leadframe having a lead finger, attaching a wirebond between the die and the leadfinger, applying a first mold material over at least a portion of the wirebond and the die and the leadfinger to form an assembly, waiting for the first mold material to at least partially cure, and applying a second mold material over the assembly.

Claims

1. An integrated circuit device, comprising:

at least one die attached to a leadframe having lead fingers;

wirebonds making connections between the at least one die and the leadfingers;

a first mold material injected at a first pressure to prevent wire sway of the wirebonds for encapsulating the wirebonds and covering at least a portion of the at least one die and the leadfingers, wherein the first mold material is only on a die-side of the leadframe and overmolds all wirebonds connected to the at least one die;

a concentrator having a first side and a second side, wherein the first side is secured to a non die-side of the leadframe;

a magnet secured to the second side of the concentrator, and

a second mold material injected at a second pressure greater than the first pressure for overmolding the at least one die, first mold material, concentrator, and magnet.

2. The device according to claim 1, wherein the first mold material encapsulates the at least one die on the leadframe.

3. The device according to claim 1, wherein the first mold material has a coefficient of expansion compatible with a coefficient of expansion for a magnet.

4. The device according to claim 1, wherein the first and second mold material are different.

5. The device according to claim 1, wherein the at least one die includes one or more magnetic field sensors.

6. The device according to claim 5, wherein the magnetic field sensor includes a Hall element.

7. The device according to claim 1, wherein the wirebond includes a gold wire.