Semiconductor device with improved encapsulation

• US 20070090545A1
• Filed: 10/24/2005
• Published: 04/26/2007
• Est. Priority Date: 10/24/2005
• Status: Abandoned Application

• Current Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Shah, Mahesh, Condie, Brian
• Application Number:
  US11/257,887
• Publication Number:
  US 20070090545A1
• Time in Patent Office: Days
• US Class Current: 257/789
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 23/295 containing a filler H01L23/296 takes precedence
• CPC Class Codes: H01L 23/4334 Auxiliary members in encapsulations H01L23/49568 takes precedence
• CPC Class Codes: H01L 24/48 of an individual wire connector
• 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 2924/01021 Scandium [Sc]
• CPC Class Codes: H01L 2924/01025 Manganese [Mn]
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/207 Diameter ranges
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding

Abstract

Structure and method are provided for plastic encapsulated semiconductor devices. The encapsulation comprises a plastic binder having a dielectric constant ε_b and loss tangent δ_b and a filler mixed therewith having lower ε_f and/or δ_f so that ε_m and/or δ_m of the mix is less than ε_b, δ_b, respectively. Hollow microspheres of varied sizes are preferred fillers, desirably in the size range of about 0.3 to 300 micrometers. These should comprise at least about 50%, more preferably 60 to 70% or more of the mixture by volume so that the resulting mix has ε_m<3, preferably <2.5 and δ_m<0.005. The encapsulant mixture is placed in proximity to or on the die so that the fringing electric fields of the die, die wiring and/or die connections are exposed to a lower ε and/or δ than that of a plastic encapsulation without the filler.

Claims

1. A semiconductor device, comprising:

a die support;

a semiconductor die mounted on a portion of the die support;

a plastic encapsulation on at least part of the die support and the die;

wherein the plastic encapsulation comprises at least two components;

a plastic binder having a dielectric constant ε

_band loss tangent δ

_b; and

a filler material having a lower dielectric constant ε

_f and/or lower loss tangent δ

_f, mixed with the plastic binder to form the plastic encapsulation having combined dielectric constant ε

_m and loss tangent δ

_m, such that either ε

_m<

ε

_b or δ

_m<

δ

_b or both ε

_m<

ε

_b and δ

_m<

δ

_b.

2. The device of claim 1, wherein the filler material comprises hollow micro spheres.

3. The device of claim 2, wherein the hollow microspheres have sizes less than about 300 micrometers diameter.

4. The device of claim 2, wherein the hollow microspheres comprise at least about 50 percent by volume of the plastic encapsulation.

5. The device of claim 1, wherein the plastic encapsulation, has a dielectric constant ε

_m less than about 3 or loss tangent δ

_m less than about 0.005, or both.

6. A plastic encapsulated semiconductor device, comprising:

a semiconductor die;

a plastic encapsulation covering one or more faces of the die, wherein the plastic encapsulation comprises a binder having dielectric constant ε

_b and loss tangent δ

_b and a filler material mixed together so as to have a resulting dielectric constant δ

_m and loss tangent δ

_m such that either ε

_m<

ε

_b or δ

_m<

δ

_b or both ε

_m<

ε

_b and δ

_m<

δ

_b.

7. The device of claim 6, wherein the filler material comprises a low density plastic.

8. The device of claim 6, wherein the filler material comprises hollow micro spheres.

9. The device of claim 8, wherein the filler comprises hollow microspheres that are between about 0.3 and 300 micro-meters in diameter.

10. The device of claim 6, wherein the filler comprises glass, ceramic or plastic particles that are between about 0.3 and 100 micro-meters in their largest dimension.

11. The device of claim 6, wherein the plastic encapsulation, has a dielectric constant ε

_m less than about 3 or loss tangent δ

_m less than about 0.005, or both.

12. The device of claim 11, wherein the plastic encapsulation, has a dielectric constant ε

_m less than about 2.5.

13. The device of claim 10, wherein the particles comprise at least 50 percent by volume of the plastic encapsulation.

14. The device of claim 13, wherein the particles comprise at least 70 percent by volume of the plastic encapsulation.

15. A method of encapsulating a semiconductor die, comprising:

mounting the die on a support;

placing the support with the die in a mold suitable for plastic encapsulation, wherein the die is located in a cavity in the mold;

placing a plastic encapsulant in the cavity of the mold to substantially encapsulate the semiconductor die, wherein the encapsulant comprises a mixture of a plastic resin having a dielectric constant ε

_b and loss tangent δ

_b and a filler material that imparts to the mixture a dielectric constant ε

_m and loss tangent δ

_m, wherein either ε

_m<

ε

_b or δ

_m<

δ

_b or both ε

_m<

ε

_b and δ

_m<

δ

_b.

16. The method of claims 15, further comprising, curing the plastic encapsulant in the mold.

17. The method of claim 15, wherein the step of placing the plastic encapsulant in the cavity of the mold comprises, placing a plastic encapsulant having a filler comprising hollow glass, ceramic, plastic microspheres or a combination thereof, whose sizes are less than about 300 micrometers.

18. The method of claim 15, wherein the step of placing the plastic encapsulant in the cavity of the mold comprises, placing a plastic encapsulant having at least 50 percent by volume of the filler.

19. The method of claim 15, wherein the step of placing the plastic encapsulant in the cavity of the mold comprises, placing a plastic encapsulant having ε

_m<

3.

20. The method of claim 19, wherein the step of placing the plastic encapsulant in the cavity of the mold comprises, placing a plastic encapsulant having δ

_m<

0.005.