# Patent

## Title
Electronic device with redistribution layer and stiffeners and related methods

## Abstract

An electronic device may include an integrated circuit (IC), electrically conductive connectors coupled to the IC, and a heat sink layer adjacent the IC and opposite the electrically conductive connectors. The electronic device may include an encapsulation material surrounding the IC and the electrically conductive connectors, a redistribution layer having electrically conductive traces coupled to the electrically conductive connectors, a stiffener between the heat sink layer and the redistribution layer, and a fan-out component between the heat sink layer and the redistribution layer and being in the encapsulation material.

## Background
RELATED APPLICATION
This application is based upon prior filed copending Chinese Application No. 201410537567.2 filed Oct. 11, 2014, the entire subject matter of which is incorporated herein by reference in its entirety.
TECHNICAL FIELD
The present disclosure relates to the field of integrated circuit devices, and, more particularly, to packaging of integrated circuit devices and related methods.
BACKGROUND
In electronic devices with integrated circuits (ICs), the ICs are typically mounted onto circuit boards. In order to electrically couple connections between the circuit board and the IC, the IC is typically “packaged.” The IC packaging usually provides a small encasement for physically protecting the IC and provides contact pads for coupling to the circuit board. In some applications, the packaged IC may be coupled to the circuit board via solder bumps.
One approach to IC packaging comprises a quad-flat no-leads (QFN) package. The QFN package may provide some advantages, such as reduced lead inductance, a near chip scale footprint, thin profile, and low weight. Also, the QFN package typically includes perimeter I/O pads to ease circuit board trace routing, and the exposed copper die-pad technology offers enhanced thermal and electrical performance. QFN packaging may be well suited for applications where size, weight, and thermal and electrical performance are important.
Referring initially to FIG. 1, a typical ball grid array (BGA) electronic device 200 is now described. The electronic device 200 includes a heat sink layer 201, a pair of stiffeners 203a-203b, and an adhesive layer 202a, 202c between the stiffeners and the heat sink layer. The electronic device 200 includes a circuit board layer 205 having electrically conductive traces 208 therein, another adhesive layer 204a-204b between the circuit board layer and the stiffeners 203a-203b, and a plurality of ball contacts 207a-207l carried by the circuit board layer. The electronic device 200 includes an IC 206, a plurality of ball contacts 209a-209j coupling the IC to the circuit board layer 205, an adhesive layer 202b between the heat sink layer 201 and the IC, and an under fill material 210 around the IC and surrounding the plurality of ball contacts.
SUMMARY
Generally, an electronic device may include an IC, a plurality of electrically conductive connectors coupled to the IC, and a heat sink layer adjacent the IC and opposite the plurality of electrically conductive connectors. The electronic device may include an encapsulation material surrounding the IC and the plurality of electrically conductive connectors, a redistribution layer having a plurality of electrically conductive traces coupled to the plurality of electrically conductive connectors, a stiffener between the heat sink layer and the redistribution layer, and a fan-out component between the heat sink layer and the redistribution layer and being in the encapsulation material.
More specifically, the electronic device may further include a thermal interface layer between the heat sink layer and the IC. The electronic device may further comprise a plurality of electrically conductive solder balls coupled to the redistribution layer. The stiffener may have an inner surface adjacent the encapsulation material and an outer surface defining an external surface of the electronic device. The stiffener may abut and retain the encapsulation material.
The redistribution layer may comprise a dielectric layer. The plurality of electrically conductive traces is carried by the dielectric layer and coupled to the plurality of electrically conductive connectors. The fan-out component may comprise a ceramic material, for example. The plurality of electrically conductive connectors may comprise at least one of a solder bump and a pillar.
Another aspect is directed to a method of making an electronic device. The method may include forming a plurality of electrically conductive connectors coupled to an IC, positioning a heat sink layer adjacent the IC and opposite the plurality of electrically conductive connectors, and forming an encapsulation material surrounding the IC and the plurality of electrically conductive connectors. The method may include positioning a redistribution layer having a plurality of electrically conductive traces coupled to the plurality of electrically conductive connectors, positioning a stiffener between the heat sink layer and the redistribution layer, and positioning a fan-out component between the heat sink layer and the redistribution layer and being in the encapsulation material.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-section view of an electronic device, according to the prior art.
FIG. 2 is a cross-section view of an electronic device, according to the present disclosure.
FIGS. 3-9 are cross-section views of steps in the method for making the electronic device of FIG. 2.



DETAILED DESCRIPTION
There may some potential drawbacks to the prior art electronic device 200. The electronic device 200 may have reliability issues with the ball contacts 207a-207l, 209a-209j due to coefficient of thermal expansion (CTE) mismatch. The electronic device 200 may suffer from warping due to external physical forces and heat. Also, the design of the electronic device 200 generates a costly manufacturing process with reduced yield. The electronic device 200 also suffers from having a large package size with a thick profile, poor routing, poor heat dispersion, poor noise control, and poor radio frequency (RF) shielding.
The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which several embodiments of the invention are shown. This present disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. Like numbers refer to like elements throughout.
Referring to FIG. 2, an electronic device 10 according to the present disclosure is now described. The electronic device 10 illustratively includes an IC 36 having a plurality of electrically conductive contacts 20a-20e, a plurality of electrically conductive connectors 21a-21e coupled to the electrically conductive contacts of the IC, and a heat sink layer 11 adjacent the IC and opposite the plurality of electrically conductive connectors. The plurality of electrically conductive connectors 21a-21e may comprise a plurality of solder bumps, or a plurality of pillars (e.g. copper, aluminum).
The electronic device 10 illustratively includes an encapsulation material 14 surrounding the IC 36 and the plurality of electrically conductive connectors 21a-21e, a redistribution layer 16 having a plurality of electrically conductive traces 18a-18k coupled to the plurality of electrically conductive connectors, a stiffener 13 between the heat sink layer 11 and the redistribution layer, and a fan-out component 15 between the heat sink layer and the redistribution layer and being in the encapsulation material. The fan-out component 15 may comprise a ceramic and/or organic material, for example. The fan-out component 15 is laterally positioned between the stiffener 13 and the IC 36. Helpfully, the prior art problem with mismatch in the CTE of the circuit board layer 205 and the ball contacts 207a-207l, 209a-209j is addressed.
More specifically, the electronic device 10 illustratively includes a thermal interface layer 12 between the heat sink layer 11 and the IC 36. The electronic device 10 illustratively includes a plurality of electrically conductive solder balls 19a-19k carried by the redistribution layer 16 to provide a BGA style connection.
The stiffener 13 coefficient of thermal expansion (CTE) has an inner surface 23 adjacent the encapsulation material 14 and an outer surface 22 defining an external surface of the electronic device 10. The stiffener 13 may abut and/or retain the encapsulation material 14 with the inner surface 23.
The redistribution layer 16 illustratively includes a dielectric layer 17. The plurality of electrically conductive traces 18a-18k is carried by the dielectric layer 17 and coupled to the plurality of electrically conductive connectors 21a-21e. Advantageously, the electronic device 10 uses no substrate under the IC 36, as in the prior art approach of FIG. 1. In the electronic device 10, the substrate is replaced with the redistribution layer 16.
Additionally, advantageously, the electronic device 10 may also be manufactured using wafer level packaging technology, and can include integrated electronic components, such as a capacitor. Also, the electronic device 10 lacks a silicon interposer for fan out, which has instead been moved to the side. The electronic device 10 also has improved reliability as compared with the prior art design, and addresses the conflict of the flip-chip bump reliability and BGA joint reliability. In addition, the electronic device 10 has improved heat dispersion efficiency, reduced warping, and low mismatch in the CTE in the materials.
Another aspect is directed to a method of making the electronic device 10. The method may include forming a plurality of electrically conductive connectors 21a-21e coupled to an IC 36, positioning a heat sink layer 11 adjacent the IC and opposite the plurality of electrically conductive connectors, and forming an encapsulation material 14 surrounding the IC and the plurality of electrically conductive connectors. The method may include positioning a redistribution layer 16 having a plurality of electrically conductive traces 18a-18k coupled to the plurality of electrically conductive connectors 21a-21e, positioning a stiffener 13 between the heat sink layer 11 and the redistribution layer, and positioning a fan-out component 15 between the heat sink layer and the redistribution layer and being in the encapsulation material 14.
Referring now additionally to FIGS. 3-9, an exemplary embodiment of a method for making the electronic device 10 is now described. It will be appreciated that the illustrated example produces two electronic devices 10a, 10b for illustrative purposes only, and that the disclosed method can manufacture more devices simultaneously using wafer level processing technology.
As shown in FIG. 3, the base for the manufacture steps is prepared and includes a carrier layer 31, and an adhesive layer 32 thereon. As shown in FIG. 4, the ICs 36a-36b, the fan-out components 15a-15b, and the stiffeners 13a-13b are placed on the adhesive layer 32, for example, using a pick and place (PnP) machine. As shown in FIG. 5, the encapsulation material 14 is formed over the carrier layer 31. As shown in FIG. 6, the upper surface of the carrier layer 31 is subjected to a grinding step to remove excess encapsulation material 14. As shown in FIG. 7, the encapsulated components are inverted on the carrier layer 31, and the redistribution layer 16 is formed. As shown in FIG. 8, the plurality of electrically conductive solder balls 19a-19k are formed adjacent the redistribution layer 16. As shown in FIG. 9, the molded panel or wafer or encapsulated components are singulated with an illustrative saw blade 33 (the saw blade stopping midway though the adhesive layer 32). The next phase would include dissolving the adhesive layer 32 to release the electronic devices 10a, 10b, and attaching respective heat sink layers 11a, 11b. 
Many modifications and other embodiments of the present disclosure will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the present disclosure is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.

## Claims

1. An electronic device comprising:
an integrated circuit (IC);
a plurality of electrically conductive connectors coupled to said IC;
a heat sink layer adjacent said IC and opposite said plurality of electrically conductive connectors;
an encapsulation material surrounding said IC and said plurality of electrically conductive connectors;
a redistribution layer having a plurality of electrically conductive traces coupled to said plurality of electrically conductive connectors;
a stiffener between said heat sink layer and said redistribution layer; and
a fan-out component between said heat sink layer and said redistribution layer and being in said encapsulation material.

2. The electronic device of claim 1 further comprising a thermal interface layer between said heat sink layer and said IC.

3. The electronic device of claim 1 further comprising a plurality of electrically conductive solder balls coupled to said redistribution layer.

4. The electronic device of claim 1 wherein said stiffener has an inner surface adjacent said encapsulation material and an outer surface defining an external surface of the electronic device.

5. The electronic device of claim 1 wherein said stiffener abuts said encapsulation material.

6. The electronic device of claim 1 wherein said redistribution layer comprises a dielectric layer; and wherein said plurality of electrically conductive traces is carried by said dielectric layer and coupled to said plurality of electrically conductive connectors.

7. The electronic device of claim 1 wherein said fan-out component comprises a ceramic material.

8. The electronic device of claim 1 wherein said plurality of electrically conductive connectors comprises at least one of a solder bump and a pillar.

9. An electronic device comprising:
an integrated circuit (IC);
a plurality of electrically conductive connectors coupled to said IC;
a heat sink layer adjacent said IC and opposite said plurality of electrically conductive connectors;
a thermal interface layer between said heat sink layer and said IC;
an encapsulation material surrounding said IC and said plurality of electrically conductive connectors;
a redistribution layer having a plurality of electrically conductive traces coupled to said plurality of electrically conductive connectors;
a stiffener between said heat sink layer and said redistribution layer and having an inner surface adjacent said encapsulation material and an outer surface defining an external surface of the electronic device; and
a fan-out component between said heat sink layer and said redistribution layer and being in said encapsulation material.

10. The electronic device of claim 9 further comprising a plurality of electrically conductive solder balls coupled to said redistribution layer.

11. The electronic device of claim 9 wherein said stiffener abuts said encapsulation material.

12. The electronic device of claim 9 wherein said redistribution layer comprises a dielectric layer; and wherein said plurality of electrically conductive traces is carried by said dielectric layer and coupled to said plurality of electrically conductive connectors.

13. The electronic device of claim 9 wherein said fan-out component comprises a ceramic material.

14. The electronic device of claim 9 wherein said plurality of electrically conductive connectors comprises at least one of a solder bump and a pillar.

15. An electronic device comprising:
an integrated circuit (IC);
a plurality of electrically conductive connectors coupled to said IC;
a heat sink layer adjacent said IC and opposite said plurality of electrically conductive connectors;
a dielectric material surrounding said IC and said plurality of electrically conductive connectors;
a redistribution layer coupled to said plurality of electrically conductive connectors;
a stiffener between said heat sink layer and said redistribution layer; and
a fan-out component between said heat sink layer and said redistribution layer and being in said dielectric material.

16. The electronic device of claim 15 further comprising a thermal interface layer between said heat sink layer and said IC.

17. The electronic device of claim 15 further comprising a plurality of electrically conductive solder balls coupled to said redistribution layer.

18. The electronic device of claim 15 wherein said stiffener has an inner surface adjacent said dielectric material and an outer surface defining an external surface of the electronic device.

19. The electronic device of claim 15 wherein said stiffener abuts said dielectric material.

20. The electronic device of claim 15 wherein said fan-out component comprises a ceramic material.

21. The electronic device of claim 15 wherein said plurality of electrically conductive connectors comprises at least one of a solder bump and a pillar.