Systems and methods for providing electromagnetic interference shielding for integrated circuit modules

Patent metadata

Field	Value
Publication number	US-9754896-B2
Application number	US-201313893605-A
Country	US
Kind code	B2
Filing date	May 14, 2013
Priority date	May 31, 2012
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

Systems and methods disclose maintaining paint thickness uniformity over the surface of a cap encapsulating at least one integrated circuit (IC) module on a panel of IC modules. The layer of conductive paint electrically couples with wirebonds on the panel to form at least part of an electromagnetic interference (EMI) or radio frequency interference (RFI) shield that attenuates EMI or RFI during operation of the IC module. Optimizing the spray nozzle diameter, fluid pressure, coaxial air pressure, spray heights, speeds, and spray pattern achieves paint thickness control. A uniform coating of conductive paint provides a more effective EMI or RFI shield during the operation of the IC modules.

First claim

What is claimed is:

1. A method to form at least part of an electromagnetic interference or radio frequency interference shield that attenuates electromagnetic interference or radio frequency interference during operation of an integrated circuit module, the method comprising:
forming at least one wirebond around a perimeter of each integrated circuit module of a plurality of integrated circuit modules on a panel;
forming an overmold over the panel such that an upper portion of the at least one wirebond of each integrated circuit module is exposed;
configuring a spray apparatus to automatically spray conductive paint, an automated operation of the spray apparatus being based at least in part on physical properties of the conductive paint and a size of the panel;
automatically spraying a plurality of separate perimeter bands of the conductive paint onto a perimeter of the panel such that the perimeter bands do not overlap and so an entire width of each of the separate bands is sprayed inward of an outer perimeter edge of the panel to avoid overspray;
automatically spraying N axially elongate first bands of the conductive paint on an upper surface of the panel inward of the perimeter bands and along a longitudinal axis of the panel and automatically advancing along a vertical axis of the panel a first distance after spraying each first band of the conductive paint until the Nth axially elongate first band is reached;
automatically spraying N+1 axially elongate second bands of the conductive paint , after spraying the N axially elongate first bands, inward of the perimeter bands along the longitudinal axis of the panel such that the N+1 axially elongate second bands interleave the N axially elongate first bands to provide an approximately uniform layer of the conductive paint over the upper surface of the panel while at the same time avoiding overspray, the layer of the conductive paint electrically coupling with the wirebonds on the panel to form at least part of an electromagnetic interference or radio frequency interference shield that attenuates electromagnetic interference or radio frequency interference during operation of at least one integrated circuit module of the plurality of integrated circuit modules; and
automatically spraying a second plurality of separate perimeter bands of the conductive paint onto the perimeter of the panel after automatically spraying the N axially elongate fist bands and before automatically spraying the N+1 axially elongate second bands such that the second plurality of separate perimeter bands do not overlap and so an entire width of each of the second plurality of separate perimeter bands is sprayed inward of an outer perimeter edge of the panel to avoid overspray.

2. The method of claim 1 wherein a thickness of the layer of the conductive paint is approximately 30 microns ± approximately 15 microns.

3. The method of claim 1 wherein a flatness of the layer of conductive paint ranges between approximately 0.25 micron and approximately 5 microns.

4. The method of claim 1 wherein the plurality of separate perimeter bands and the second plurality of separate perimeter bands define a layer of conductive paint over the perimeter of the panel, the layer of conductive paint over the upper surface of the panel is in electrical contact with the layer of conductive paint over the perimeter of the panel, both layers forming the at least part of the electromagnetic interference or radio frequency interference shield that attenuates the electromagnetic interference or radio frequency interference during operation of the at least one integrated circuit module.

5. The method of claim 1 wherein the electromagnetic interference or radio frequency interference shield includes the layer of the conductive paint in electrical contact with a plurality of wirebonds encircling the at least one integrated circuit module.

6. The method of claim 1 further comprising controlling parameters of the spray apparatus, the parameters including at least one of a valve pressure, a needle size, an air cap, a fluid pressure, an air assist pressure, a fluid on time, a fluid off time, an air assist on time, an air assist off time, a height of a nozzle above the upper surface, a travel speed of the nozzle, and an initial position of the nozzle.

7. The method of claim 1 wherein metal particles included in the conductive paint include metal flakes having an irregular shape and the second bands of the conductive paint being interspersed with the first bands of the conductive paint to approximately cover the upper surface of the panel with the metal flakes.

8. The method of claim 1 wherein N+1 is determined by rounding up a height of the panel minus twice a width of the perimeter band of the conductive paint divided by a width of the second band of the conductive paint to an integer value.

9. The method of claim 1 wherein the wirebonds electrically couple to a ground plane to form an interconnected shielded volume that attenuates the electromagnetic interference or radio frequency interference during operation of the at least one integrated circuit module.

10. A method to provide at least part of an electromagnetic interference or radio frequency interference shield that attenuates electromagnetic interference or radio frequency interference during operation of an integrated circuit module, the method comprising:
forming at least one wirebond around a perimeter of each integrated circuit module of a plurality of integrated circuit modules formed on a panel;
forming an overmold over the panel such that an upper portion of the at least one wirebond of each integrated circuit module is exposed;
controlling a first set of parameters of a spray apparatus based at least in part on viscosity of a conductive paint and a size of metal particles in the conductive paint;
determining a second set of parameters, the second set of parameters based at least in part on at least one of the first set of parameters;
automatically spraying a plurality of separate perimeter bands of the conductive paint onto a perimeter of the panel such that the perimeter bands do not overlap and so an entire width of each of the separate bands is sprayed inward of an outer perimeter edge of the panel to avoid overspray;
automatically spraying the conductive paint from the spray nozzle to form N axially elongate first bands of the conductive paint and N+1 axially elongate second bands of the conductive paint along a longitudinal axis of the panel, the N axially elongate first bands separated by a first distance from one another and the N+1 axially elongate second bands separated by a second distance from one another, the N axially elongate first bands and N+1 axially elongate second bands being sprayed inward of the plurality of separate perimeter bands to avoid overlap with the previously sprayed perimeter bands, the N+1 axially elongate second bands being sprayed after spraying the N axially elongate first bands and such that the N+1 axially elongate second bands interleave the N axially elongate first bands to provide an approximately uniform layer of the conductive paint over at least a portion of the upper surface of the panel while at the same time avoiding overspray, the layer of the conductive paint electrically coupling with the at least one wirebond of at least one integrated circuit module of the plurality of integrated circuit modules to form at least part of an electromagnetic interference or radio frequency interference shield; and
automatically spraying a second plurality of separate perimeter bands of the conductive paint onto the perimeter of the panel after automatically spraying the N axially elongate fist bands and before automatically spra

Assignees

• Skyworks Solutions Inc

Inventors

• Read Matthew Sean
• Nguyen Hoang Mong
• Gonzalez Sergio Joaquin
• Herrera Luis Eduardo

Classifications

• H10W90/754

  between a chip and a stacked insulating package substrate, interposer or RDL · CPC title

• H10W90/734

  between a chip and a stacked insulating package substrate, interposer or RDL · CPC title

• H10W74/00

  Encapsulations, e.g. protective coatings · CPC title

• H10W72/884

  Die-attach connectors and bond wires · CPC title

• H10W72/0198

  batch processes · CPC title