Systems and methods for electromagnetic interference shielding

Discussed generally herein are methods and devices including or providing an electromagnetic interference (EMI) shielding. A device can include a substrate including electrical connection circuitry therein, grounding circuitry on, or at least partially in the substrate, the grounding circuitry at least partially exposed from a surface of the substrate, a die electrically connected to the connection circuitry and the grounding circuitry, the die on the substrate, and a conductive foil or conductive film surrounding the die, the conductive foil or conductive film electrically connected to the grounding circuitry.

TECHNICAL FIELD

This disclosure relates generally to electromagnetic interference (EMI) shielding. One or more embodiments regard a manufacturing process to provide an EMI shielding for an electronics package. One or more embodiments regard the EMI shielded packages produced using one of the manufacturing processes.

BACKGROUND ART

Electromagnetic sources can generate electrical signals that can cause Electromagnetic interference (EMI). EMI is an electromagnetic wave or signal generated by an external source that negatively affects a circuit. The electromagnetic wave or signal can affect the circuit through electromagnetic induction, electrostatic coupling, and/or conduction. The electromagnetic wave can degrade the performance of the circuit or even stop it from functioning.

DESCRIPTION OF EMBODIMENTS

The following description and the drawings sufficiently illustrate embodiments to enable those skilled in the art to practice them. Other embodiments can incorporate structural, logical, electrical, process, or other changes. Portions and features of some embodiments can be included in, or substituted for, those of other embodiments. Embodiments set forth in the claims encompass all available equivalents of those claims.

An EMI shielding for an electronics package (e.g., a molded or unmolded system in package (SiP)) uses a physical vapor deposition (PVD) sputtering process to coat a mold surface with a conductive material. The sputtering process has some disadvantages, such as high cost of the sputtering equipment, increase in throughput time to increase sputtered conductive material thickness, complex process for uniform material coverage on package sidewalls, and mold surface pre clean to improve adhesion, among others.

Embodiments discussed herein provide EMI shielding for an electronic package, such as a system in package (SiP). Generally a metal foil or film is formed around the SiP such that the metal foil contacts one or more ground pads (e.g., on or at least partially in the package surface) or one or more ground traces/planes of the SiP. Two manufacturing techniques (each with multiple variations) are discussed herein. The first process discussed is a manufacturing process for strip-level molded packages. In this process a foil or film is attached to a mold chase prior to mold fill. The second process discussed is a manufacturing process for singulated molded packages. In this process a metal foil or film is stamped, pressed, or otherwise formed around the SiP to make contact with the one or more grounding planes/traces exposed on the sides of the package substrate.

The manufacturing processes discussed herein can provide one or more advantages over prior EMI shielding techniques and/or devices with EMI shielding. An advantage can include avoiding sputtering and the relatively high costs associated therewith. Another advantage can include a reduced throughput time as compared to a sputtering process.

The two manufacturing processes are discussed in turn. The first process, which can be useful for smaller packages normally fabricated using strip-level dies (among others), is discussed with regard toFIGS. 1A-1J. The second process, which can be useful for singulated die packages containing one or more devices (among others), is discussed with regard toFIGS. 2A-2F. In the first process, a conductive foil or film is attached to a mold chase. The foil or film is then attached to ground pads on a package substrate prior to optional molding. In the second process, a package is molded prior to foil or film attach.

A “foil” as used herein is a conductor, such as a substantially pure metal. A “film” as used herein is a combination of a dielectric material (e.g., an organic material) and a conductive material attached to each other. The remaining discussion refers to foils. However, it is to be understood that a film can be used in place of a foil.

FIG. 1Aillustrates, by way of example, a cross-section diagram of an embodiment of a system100A for adhering a foil104to a mold chase. The system100A as illustrated includes a top mold chase102A, a bottom mold chase102B, a foil104, and an adhesive106.

The top mold chase102A and the bottom mold chase102B form a main body of a mold. The mold chase102A-B is used to form the foil104to a shape defined by the top mold chase102A and the bottom mold chase102B. The top mold chase102A and the bottom mold chase102B include mold cavity registers to help ensure correct alignment of the mold chases102A-B and to help ensure the foil104is formed to a desired shape.

The foil104can include a pliable (e.g., bendable, foldable, deformable, or the like) conductive material, such as copper, aluminum, gold, titanium, silver, stainless steel, a laminate conductive material, or a combination thereof, among others. A film, which can be used in place of the foil104, can include a foil attached to another layer of material, such as can include an organic material, such as polypropylene, polyethylene terephthalate, and/or polyethylene, among others. The organic material of the film can be chosen for its bonding characteristics (its ability to be attached to the top mold chase102A using the adhesive106). Such configurations are beneficial when the foil104alone does not bond well to the top mold chase102A.

The adhesive106can be a thermal plastic or other adhesive that is pliable. The adhesive106generally has a weaker adhesive strength when heated as compared to its adhesive strength at colder temperature. Example adhesives include glue(s), pressure sensitive adhesives, spray adhesives, fabric adhesives, epoxy, and polyurethane, among others.

The adhesive106is situated on the foil104. The foil104and adhesive106combination is situated between the top mold chase102A and the bottom mold chase102B. The top and bottom mold chases102A-B are pressed together in the direction of the arrows108. The adhesive106adheres the foil104to the top mold chase102A. When the bottom mold chase102B is pulled away from the top mold chase102A the bond between the adhesive106, the top mold chase102A and the foil104keeps the foil104attached to the top mold chase102A.

FIG. 1Billustrates a cross-section view diagram of an embodiment of a system100B that includes the system100A after the bottom mold chase102B is pulled away from the top mold chase102A. As previously discussed, the bond between the adhesive106, foil104, and the top mold chase102A keeps the foil104attached to the top mold chase102A.

FIG. 1Cillustrates a cross-section view diagram of an embodiment of a system100C that includes the system100B with a strip110of packages112situated under the top mold chase102A with the foil104attached thereto. The strip110includes a plurality of packages112attached thereto. The strip110is different from a wafer. A wafer is a medium on which dies are formed, while a strip includes packaged dies (i.e. packages) situated thereon or at least partially therein. The strip110can include a substrate, such as can include a plurality of build-up layers, such as can include bumpless buildup layers. The substrate can include electrical connection circuitry at least partially therein and/or thereon. The electrical connection circuitry can include one or more traces, vias, or other conductive circuitry to connect to die circuitry in the package112.

The strip110can include traces120, pads116, and other circuitry therein to connect to circuitry of the package112, such as through connections118. The pads116are ground connected, such as to a ground of the package, such as through the trace(s)120and/or a ground plane of the strip110. Each of the pads116includes some conductive adhesive114thereon. The conductive adhesive can include tin, copper, nickel, gold, indium, silver, antimony, aluminum, oxides thereof, or a composite of a thermosetting epoxy and a metal. In one or more embodiments, the conductive adhesive is a solder. The packages112can be flip-chip, wire bond, or otherwise attached to the strip110, such as through the connections118.

FIG. 1Dillustrates a cross-section view of a system100D that includes the system100C after the top mold chase102A and attached foil104have been pressed onto the strip110. Heat can be applied to the system100D. The heat can melt the solder or activate the conductive adhesive114. The heat can reduce a bond between the foil104and the adhesive106, such as to allow the foil104to be detached from the top mold chase102A.

The system100D can be cooled. Cooling the system100D can harden the solder or solidify an electrical connection between the conductive adhesive114and the foil104, such as to form a bond between the foil104and conductive adhesive114that is stronger than the bond between the foil104and the adhesive106. Thus, the foil104can remain attached to the pad116through the conductive adhesive114when the top mold chase102A is removed therefrom.

FIG. 1Eillustrates a system100E that includes the system100D after an optional molding material126is injected on and around the package112. The molding material126is an insulating material, such as can include epoxy resins that are thermoplastic or thermosets, such as cresol novolac or bisphenol. Additionally or alternatively, the molding material126can include inorganic filler, catalyst, flame retardant, stress modifier, and/or an adhesion promoter, among others. The molding material126provides a support structure for the foil104. The molding material126can help prevent electrical connections (traces, pads, vias, or the like) from shorting.

The molding material126can be injected through a mold runner123, such as shown inFIG. 1F. A mold vent125can allow air to escape during molding material126injection.FIG. 1Fillustrates a cross-section diagram of an embodiment of a system100F that includes the mold runner123and the mold vent125.

FIG. 1Gillustrates an embodiment of a system100G that includes the system100E or100F after the top mold chase102A has been removed and during a die singulation process. The foil104is attached to the pad116through the conductive adhesive114. Conductive connectors122can be attached to the strip110, such as before or after the die singulation process. The conductive connectors122can include ball grid array (BGA), land grid array, or other electrical connections. The conductive connectors122can be electrically coupled or connected to connection circuitry in the strip110and/or one or more of the connections118.

The die singulation process can include cutting all the way through the strip110to separate packages112and associated connection circuitry in the strip110. The die singulation can be performed with a saw, bevel, laser ablation, scribe and cleave, or the like. A die package singulated with a portion of the strip110and with or without the connectors122is sometimes referred to as a SiP herein.

FIG. 1Hillustrates a system100H that includes a package112with EMI shielding. The foil104attached to the grounding pads116provides a grounded EMI shielding around the package112, such as to help reduce an amount of EMI on the die package112. The foil104can at least partially surround the package112, such as to surround the die package112on up to five sides (any sides with the exception of the bottom side where the package112is attached to the connections118).

FIG. 1Iillustrates, by way of example, a perspective view diagram of an embodiment of a system100I that is an embodiment of the system100H viewed in the direction of arrow labelled “1I/1J” inFIG. 1H. The foil104and conductive adhesive114are transparent so as to not obscure a view of the grounding pads116. In one or more embodiments, the grounding pads116can be situated around the package112, such as to provide multiple connection points for the foil104. The grounding pads116help keep the foil104attached to the strip110, such as to completely surround the package112.

FIG. 1Jillustrates, by way of example, a perspective view diagram of an embodiment of a system100J that is an embodiment of the system100H viewed in the direction of arrow labelled “1I/1J” inFIG. 1H. In the embodiment of the system100J, the grounding pad116is a single conductive pad around an entire perimeter of the package112.

FIG. 2Aillustrates, by way of example, a cross-section diagram of an embodiment of a system200A for EMI shielding. The system200A as illustrated includes multiple SiPs on a carrier232that is on a redistribution panel234. The carrier232can be coupled to the redistribution panel234through a tacky material233.

Each of the SiPs, as illustrated, includes a substrate228, a package112, and a molding material126over and around the package112and between the connections118(connections not labelled inFIG. 2Aso as to not obscure the view, seeFIGS. 1C-1Hfor a view of the connections118). Each of the packages includes the connectors122attached thereto. In the embodiments of theFIGS. 1A-1J, the substrate is provided by the strip110.

A ground plane230is situated in the substrate228. The ground plane230can include a variety of shapes, such as one of those shown inFIGS. 3A-3D, among others. The die packages112are electrically coupled to the ground plane230through the traces120.

The carrier232is a material that provides an area on which the packages can be placed and pressed between a mold chase236and the redistribution panel234, such as without slipping or damaging the connectors122. The carrier232can include an elastomeric material, such as to help cushion the packages under pressure from the top mold chase236(seeFIG. 2B).

The tacky material233(e.g., an adhesive) can be coated or otherwise situated on the redistribution panel234. The tacky material233can include a thermal release tape, thermoplastic, polyimide adhesive film, Poly-vinyl chloride (PVC) film, pressure sensitive acrylic based adhesive, ultra-violet (UV) release film, and/or a polyester based adhesive, among others. Objects can be coupled to the redistribution panel234through the tacky material233.

The redistribution panel234is a sheet of material on which packages are placed in specific (precise) x-y locations. The redistribution panel234can include a material on which the carrier232can be adhered or situated. The redistribution panel234is a relatively rigid material that can be transported without deforming or altering the location of the packages on the carrier232.

FIG. 2Billustrates, by way of example, a cross-section diagram of an embodiment of a system200B for adhering a foil104to a SiP. The system200B as illustrated includes the top mold chase236, the foil104, and the conductive adhesive114. The top mold chase236is used to form the foil104to a shape defined by the top mold chase236and the SiP. The top mold chase236is pressed on the SiPs in the direction of arrows238. The conductive adhesive114contacts the grounding plane230and forms an electrical path between the foil104and the grounding plane230. WhileFIG. 2Billustrates the conductive adhesive114as being on the foil104, the conductive adhesive114can alternatively be situated on edges of the grounding plane230.

FIG. 2Cillustrates, by way of example, a cross-section diagram of an embodiment of a system200C that includes the system200B after the top mold chase236is pressed to adhere the foil104to the grounding plane230. Heat can be applied to the system200B and/or200C to activate the conductive adhesive114. The system200C can be cooled, such as to solidify a bond between the foil104and the grounding plane230formed by the conductive adhesive114.FIG. 2Dillustrates, by way of example, a cross-section diagram of an embodiment of a system200D that includes the system200C after the top mold chase236is removed therefrom.

FIG. 2Eillustrates, by way of example, a system200E that includes the system200D during a die singulation process. The die singulation process can include cutting all the way through the foil104and the adhesive114to separate the SiPs. The die singulation can be performed with saw, bevel, laser ablation, scribe and cleave, or the like.

FIG. 2Fillustrates a system200F that includes a SiP with EMI shielding. The foil104attached to the grounding plane230(via the conductive adhesive114) provides a grounded shielding at least partially around the package112, such as to help reduce an amount of EMI that affects the SiP. The foil104can at least partially surround the package112. In the embodiment illustrated inFIG. 2F, the foil104surrounds the entire package except for a bottom surface of the substrate228(the surface on which the connectors122are attached).

The process illustrated inFIGS. 2A-2Eproduces a system with a different configuration than the process illustrated inFIGS. 1A-G. For example, the foil104of the process ofFIGS. 2A-2Eneed not have the mold runner123or the mold vent125because the package is molded prior to foil attach. Another example difference includes the attachment location of the foil104. In the system100H, the foil104is attached to a grounding pad116exposed at a top surface of the strip110, while in the system200F, the foil104is attached to a grounding plane230that is under the surface of the substrate228and exposed at edges of the substrate228.

FIGS. 3A, 3B, 3C, and 3Dillustrate, by way of example, various embodiments of grounding planes230A,230B,230C, and230D configurations, respectively.FIG. 3Aillustrates, by way of example, an embodiment of a grounding plane230A that spans an entirety of a layer of the substrate228. In such an embodiment, a via334and a dielectric isolation336can be used to pass signals through the grounding plane230A.

FIG. 3Billustrates, by way of example, an embodiment of a grounding plane230B that does not span an entirety of a layer of the substrate228. In such an embodiment, vias334outside of the grounding plane230B can pass between layers without needing to pass through the grounding plane230B.

FIGS. 3C and 3Dillustrate, by way of example, of embodiments of grounding planes230C and230D that include irregular configurations. Such embodiments are intended to illustrate that the grounding plane230can take any general form as long as it is exposed along edges of the substrate228.

Using a film or foil in place of a sputtered material as described with regard to the preceding FIGS. provides a more robust (e.g., stronger, harder to break, more reliable, or the like) EMI shielding. Unlike with sputtering material, a wider variety of metal and/or alloy compositions can be used. Using a film or foil, the thickness of the EMI shielding is not limited like it is using a sputtered material. The foil or film is generally denser and has fewer defects, such as voids, cracks, or other defects. Such defects can be detected using a microscope or inspection by the naked eye. The foil or film generally has a more uniform thickness over a curved surface as compared to a sputtered material. Such differences make the foil or film as discussed herein physically different from a sputtered material. Such differences can be detected by the naked eye or with the aid of a microscope.

FIG. 4shows a block diagram example of an electronic device which can include an EMI shielding as disclosed herein. An example of an electronic device using one or more packages with one or more higher resistance via is included to show an example of a device application for the present disclosure. Electronic device400is merely one example of a device in which embodiments of the present disclosure can be used. Examples of electronic devices400include, but are not limited to, personal computers, tablet computers, supercomputers, servers, telecommunications switches, routers, mobile telephones, personal data assistants, MP3 or other digital music players, radios, or the like.

In the example ofFIG. 4, electronic device400comprises a data processing system that includes a system bus402to couple the various components of the system. System bus402provides communications links among the various components of the electronic device400and can be implemented as a single bus, as a combination of busses, or in any other suitable manner.

An electronic assembly410is coupled to system bus402. The electronic assembly410can include a circuit or combination of circuits. In one embodiment, the electronic assembly410includes a processor412which can be of any type. As used herein, “processor” means any type of computational circuit, such as but not limited to a microprocessor, a microcontroller, a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a graphics processor, a digital signal processor (DSP), multiple core processor, or any other type of processor or processing circuit.

Other types of circuits that can be included in electronic assembly410are a custom circuit, an application-specific integrated circuit (ASIC), or the like, such as, for example, one or more circuits (such as a communications circuit414) for use in wireless devices like mobile telephones, pagers, personal data assistants, portable computers, two-way radios, and similar electronic systems. The IC can perform any other type of function.

The electronic device400can include an external memory420, which in turn can include one or more memory elements suitable to the particular application, such as a main memory422in the form of random access memory (RAM), one or more hard drives424, and/or one or more drives that handle removable media426such as compact disks (CD), digital video disk (DVD), and the like.

The electronic device400can also include a display device416, one or more speakers418, and a keyboard and/or controller430, which can include a mouse, trackball, touch screen, voice-recognition device, or any other device that permits a system user to input information into and receive information from the electronic device400.

Additional Notes and Examples

In Example 1 a device with electromagnetic interference (EMI) shielding can include a substrate including electrical connection circuitry therein, grounding circuitry on, or at least partially in the substrate, the grounding circuitry at least partially exposed from a surface of the substrate, a die electrically connected to the connection circuitry and the grounding circuitry, the die on the substrate, and a conductive foil or conductive film surrounding the die, the conductive foil or conductive film electrically connected to the grounding circuitry.

In Example 2 the device of Example 1 can include, wherein the conductive foil or conductive film surrounds the die package on five sides of the die.

In Example 3 the device of at least one of Examples 1-2 can include, wherein the conductive foil or conductive film is a conductive foil.

In Example 4 the device of at least one of Examples 1-2 can include, wherein the conductive foil or conductive film is a conductive film.

In Example 5 the device of at least one of Examples 1-4 can include, wherein the grounding circuitry is a grounding plane in the substrate.

In Example 6 the device of at least one of Examples 1-4 can include, wherein the grounding circuitry is one or more grounding pads on a top surface of the substrate, the top surface of the substrate facing the die.

In Example 7 the device of at least one of Examples 1-6 can include one or more solder balls electrically and mechanically connected to a bottom surface of the substrate, the bottom surface of the substrate opposite a/the top surface of the substrate.

In Example 8 the device of at least one of Examples 1-7 can include a mold runner hole and a mold vent hole in the conductive foil or the conductive film, and a molding material on and around the die, the molding material in contact with the die and the conductive foil or film.

In Example 9 the device of at least one of Examples 1-5 and 7-8 can include, wherein the grounding circuitry is a grounding plane and the device further comprises a layer of conductive adhesive between the conductive foil or conductive film and the grounding plane, the conductive foil or conductive film and the substrate, and the conductive foil or conductive film and the molding material.

In Example 10 a method for providing electromagnetic interference (EMI) shielding for a System in Package (SiP) can include pressing an adhesive and a conductive foil or conductive film onto a mold chase so as to adhere the conductive foil to the mold chase, aligning a strip of dies with the mold chase, pressing the mold chase with the conductive foil adhered thereto onto the strip of dies to form and electrical connection between the conductive foil and grounding pads on the strip, injecting molding material between the conductive foil or conductive film and the dies after pressing the mold chase onto the strip, and singulating the dies from the strip.

In Example 11 the device of Example 10 can include heating solder on the grounding pads to melt the solder, and cooling the solder to solidify the electrical connection between the conductive foil or conductive film and the grounding pads.

In Example 12 the device of at least one of Examples 10-11 can include heating the adhesive to reduce a bond strength between the conductive foil or conductive film and the mold chase.

In Example 13 the device of at least one of Examples 10-12 can include, wherein injecting the molding material includes injecting the molding material into a mold runner hole in the conductive film or conductive foil.

In Example 14 the device of at least one of Examples 10-13 can include electrically connecting solder balls to a bottom surface of the strip before singulating the dies, the bottom surface of the strip opposite a surface of the strip on which the conductive foil or conductive film is electrically connected.

In Example 15 the device of at least one of Examples 10-14 can include electrically connecting solder balls to a bottom surface of the strip after singulating the dies, the bottom surface of the strip opposite a surface of the strip on which the conductive foil or conductive film is electrically connected.

In Example 16 a method for providing electromagnetic interference (EMI) shielding for a System in Package (SiP) can include situating a conductive film or conductive foil under a mold chase, aligning a redistribution panel with dies thereon with the mold chase, each of the dies including a molding material around a respective die, pressing the mold chase towards the redistribution panel to form an electrical connection between the conductive foil or conductive film and the grounding planes of the dies, and singulating the die packages by cutting through the conductive foil or conductive film between respective dies.

In Example 17 the device of Example 16 can include, wherein the conductive foil or conductive film includes a layer of conductive adhesive on a surface of the conductive foil or conductive film facing the dies.

In Example 18 the device of Example 17 can include, wherein after pressing the mold chase towards the redistribution panel the conductive adhesive is further situated between the conductive foil or conductive film and the molding material of the dies.

In Example 19 the device of Example 16 can include, wherein the grounding planes include conductive adhesive thereon prior to pressing the mold chase towards the redistribution panel and the conductive foil or conductive film does not include conductive thereon prior to pressing the mold chase towards the redistribution panel to form the electrical connection between the conductive foil or conductive film and the grounding planes.

In Example 20 the device of at least one of Examples 16-19 can include situating the dies on a carrier on the redistribution panel, the carrier including an elastomeric material to protect the dies while pressing the mold chase.