Non-homogeneous molding of packaged semiconductor devices

• US 9,202,770 B1
• Filed: 09/01/2014
• Issued: 12/01/2015
• Est. Priority Date: 09/01/2014
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Foong, Chee Seng, Tan, Lan Chu
• Primary Examiner(s): Whalen, Daniel
• Assistant Examiner(s): CIESLEWICZ, ANETA B
• Application Number:
  US14/474,291
• Time in Patent Office: 456 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B29B 9/12 characterised by structure or composition
• CPC Class Codes: B29C 45/02 Transfer moulding, i.e. transferring the required volume of moulding material by a plunger from a "shot" cavity into a mould cavity
• CPC Class Codes: B29C 45/14655 connected to or mounted on a carrier, e.g. lead frame
• CPC Class Codes: B29C 45/1634 with a non-uniform dispersion of the moulding material in the article, e.g. resulting in a marble effect
• CPC Class Codes: B29C 45/1671 with an insert
• CPC Class Codes: B29C 45/462 Injection of preformed charges of material
• CPC Class Codes: H01L 21/565 Moulds
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 23/3128 the substrate having spherical bumps for external connection
• CPC Class Codes: H01L 23/3675 characterised by the shape of the housing
• CPC Class Codes: H01L 23/3737 Organic materials with or without a thermoconductive filler
• CPC Class Codes: H01L 23/4334 Auxiliary members in encapsulations H01L23/49568 takes precedence
• 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

A packaged semiconductor device has an integrated circuit (IC) die and first and second volumes of molding compound. The first volume of molding compound is disposed on a first portion of a first side of the IC die and comprises a first molding compound. The second volume of molding compound is disposed on a second side of the IC die, different from the first side, and comprises a second molding compound, different from the first molding compound. By including different molding compounds, the properties of the packaged semiconductor device can be varied across the device.

Claims

1. A method for assembling a packaged semiconductor device, the method comprising:

(a) positioning a partially-assembled packaged semiconductor device comprising an integrated circuit (IC) die within a mold cavity;

(b) positioning a molding compound pellet within a pot, wherein the molding compound pellet comprises a first molding compound and a second molding compound different from the first molding compound;

(c) pushing the second molding compound into a second volume of the mold cavity disposed on a second side of the IC die; and

(d) pushing the first molding compound into a first volume of the mold cavity disposed on at least a first portion of a first side of the IC die, different from the second side, and

after step (c) and before step (d), pushing a mixture of the first and second molding compounds from the first and second regions into a third volume of the mold cavity,

wherein the molding compound pellet comprises (i) a first region comprising the first molding compound and (ii) a second region comprising the second molding compound and a recess, wherein the first region is located within the recess of the second region.

2. The method of claim 1, wherein:

the first portion is within a perimeter of the IC die; and

the second volume is further disposed on a second portion of the first side of the IC die, wherein the second portion comprises the perimeter of the IC die.

3. The method of claim 1, wherein the third volume is situated between the first and second volumes.

4. The method of claim 3, wherein the mixture is pushed into the third volume such that:

a concentration of the first molding compound in the mixture is highest nearest to a center of the IC die and decreases away from the center of the IC die; and

a concentration of the second molding compound in the mixture is highest away from the center of the IC die and decreases toward the center of the IC die.

5. The method of claim 1, wherein the first volume has a substantially conical, frustum shape.

6. The method of claim 1, wherein the first molding compound comprises one or more of the following properties:

(i) a higher thermal conductivity than the second molding compound;

(ii) a higher viscosity at molding temperature than the second molding compound; and

(iii) a higher elastic modulus than the second molding compound.

7. The method of claim 1, wherein:

the molding compound pellet further comprises a third region comprising the first molding compound, wherein the third region is in a stacked arrangement with the first and second regions; and

step (d) comprises pushing the third region into the mold cavity.

8. The method of claim 7, wherein:

the molding compound pellet further comprises a fourth region comprising the second molding compound, wherein the fourth region is in a stacked arrangement with the first and second regions, opposite the third region; and

step (c) comprises pushing the fourth region into the mold cavity.

9. The method of claim 7, wherein:

the molding compound pellet further comprises a third region comprising the second molding compound, wherein the third region is in a stacked arrangement with the first and second regions; and

step (c) comprises pushing the third region into the mold cavity.