FIELD OF THE INVENTION
The invention relates generally to semiconductor device packages. More particularly, the invention relates to semiconductor device packages with electromagnetic interference shielding.
BACKGROUND
Semiconductor devices have become progressively more complex, driven at least in part by the demand for enhanced processing speeds and smaller sizes. While the benefits of enhanced processing speeds and smaller sizes are apparent, these characteristics of semiconductor devices also can create problems. In particular, higher clock speeds can involve more frequent transitions between signal levels, which, in turn, can lead to a higher level of electromagnetic emissions at higher frequencies or shorter wavelengths. Electromagnetic emissions can radiate from a source semiconductor device, and can be incident upon neighboring semiconductor devices. If the level of electromagnetic emissions at a neighboring semiconductor device is sufficiently high, these emissions can adversely affect the operation of that semiconductor device. This phenomenon is sometimes referred to as electromagnetic interference (“EMI”). Smaller sizes of semiconductor devices can exacerbate EMI by providing a higher density of those semiconductor devices within an overall electronic system, and, thus, a higher level of undesired electromagnetic emissions at a neighboring semiconductor device.
One way to reduce EMI is to shield a set of semiconductor devices within a semiconductor device package. In particular, shielding can be accomplished by including an electrically conductive casing or housing that is electrically grounded and is secured to an exterior of the package. When electromagnetic emissions from an interior of the package strike an inner surface of the casing, at least a portion of these emissions can be electrically shorted, thereby reducing the level of emissions that can pass through the casing and adversely affect neighboring semiconductor devices. Similarly, when electromagnetic emissions from a neighboring semiconductor device strike an outer surface of the casing, a similar electrical shorting can occur to reduce EMI of semiconductor devices within the package.
While an electrically conductive casing can reduce EMI, the use of the casing can suffer from a number of disadvantages. In particular, the casino is typically secured to an exterior of a semiconductor device package by an adhesive. Unfortunately, the casing can be prone to peeling or falling off, since binding characteristics of the adhesive can be adversely affected by temperature, humidity, and other environmental conditions. Also, when securing the casing to the package, the size and shape of the casing and the size and shape of the package should match within relatively small tolerance levels. This matching of sizes and shapes and associated precision in relative positioning of the casing and the package can render manufacturing operations costly and time consuming. Because of this matching of sizes and shapes, it also follows that semiconductor device packages of different sizes and shapes can require different casings, which can further increase manufacturing cost and time to accommodate the different packages.
It is against this background that a need arose to develop the semiconductor device packages and related methods described herein.
SUMMARY
One aspect of the invention relates to semiconductor device packages with EMI shielding. In one embodiment, a semiconductor device package includes: (1) a substrate unit including (a) an upper surface, (b) a lower surface, (c) a lateral surface disposed adjacent to a periphery of the substrate unit, and (d) a grounding element disposed adjacent to the periphery of the substrate unit; (2) a semiconductor device disposed adjacent to the upper surface of the substrate unit and electrically connected to the substrate unit; (3) a package body disposed adjacent to the upper surface of the substrate unit and covering the semiconductor device; and (4) an EMI shield disposed adjacent to exterior surfaces of the package body and electrically connected to a connection surface of the grounding element. A lateral surface of the package body is substantially aligned with the lateral surface of the substrate unit, and the connection surface of the grounding element is electrically exposed adjacent to the lateral surface of the substrate unit. The grounding element corresponds to a remnant of a grounding via, and provides an electrical pathway to ground electromagnetic emissions incident upon the EMI shield.
In another embodiment, the semiconductor device package includes: (1) a substrate unit including (a) a first surface, (b) a second opposing surface, and (c) a grounding element at least partially extending between the first surface and the second opposing surface; (2) a semiconductor device disposed adjacent to the first surface of the substrate unit and electrically connected to the substrate unit; (3) a package body disposed adjacent to the first surface of the substrate unit and covering the semiconductor device and the grounding element; and (4) an EMI shield disposed adjacent to exterior surfaces of the package body and electrically connected to a lateral surface of the grounding element. The lateral surface of the grounding element is disposed adjacent to a periphery of the substrate unit, such that the lateral surface of the grounding element is electrically exposed. The grounding element provides an electrical pathway to ground electromagnetic emissions incident upon the EMI shield, and a lateral profile of the semiconductor device package is substantially planar and is substantially orthogonal with respect to the second opposing surface of the substrate unit.
Another aspect of the invention relates to methods of forming semiconductor device packages with EMI shielding. In one embodiment, a method includes: (1) providing a substrate including (a) an upper surface, (b) a lower surface, and (c) grounding vias at least partially extending between the upper surface and the lower surface; (2) electrically connecting a semiconductor device to the upper surface of the substrate; (3) applying a molding material to the upper surface of the substrate to form a molded structure covering the grounding vias and the semiconductor device; (4) forming cutting slits extending through the molded structure and the substrate, and the cutting slits are aligned with the substrate, such that: (a) the substrate is sub-divided to form a substrate unit; (b) the molded structure is sub-divided to form a package body disposed adjacent to the substrate unit; and (c) remnants of the grounding vias correspond to grounding elements disposed adjacent to a periphery of the substrate unit; and (5) applying an EMI coating to exterior surfaces of the package body and exposed connection surfaces of the grounding elements to form an EMI shield.
Other aspects and embodiments of the invention are also contemplated. The foregoing summary and the following detailed description are not meant to restrict the invention to any particular embodiment but are merely meant to describe some embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the nature and objects of some embodiments of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings. In the drawings, like reference numbers denote like elements, unless the context clearly dictates otherwise.
FIG. 1 illustrates a perspective view of a semiconductor device package implemented in accordance with an embodiment of the invention.
FIG. 2 illustrates a cross-sectional view of the semiconductor device package of FIG. 1, taken along line A-A of FIG. 1.
FIG. 3 illustrates an enlarged, cross-sectional view of a portion of the semiconductor device package of FIG. 1.
FIG. 4 illustrates a cross-sectional view of a semiconductor device package implemented in accordance with another embodiment of the invention.
FIG. 5A through FIG. 5E illustrate a method of forming the semiconductor device package of FIG. 1 according to an embodiment of the invention.
FIG. 6 illustrates a method of forming the semiconductor device package of FIG. 4, according to another embodiment of the invention.
DETAILED DESCRIPTION
Definitions
The following definitions apply to some of the aspects described with respect to some embodiments of the invention. These definitions may likewise be expanded upon herein.
As used herein, the singular terms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a grounding element can include multiple grounding elements unless the context clearly dictates otherwise.
As used herein, the term “set” refers to a collection of one or more components. Thus, for example, a set of layers can include a single layer or multiple layers. Components of a set also can be referred to as members of the set. Components of a set can be the same or different. In some instances, components of a set can share one or more common characteristics.
As used herein, the term “adjacent” refers to being near or adjoining. Adjacent components can be spaced apart from one another or can be in actual or direct contact with one another. In some instances, adjacent components can be connected to one another or can be formed integrally with one another.
As used herein, the terms “inner,” “outer,” “upper,” “upwardly,” “lower,” “downwardly,” “lateral,” and “laterally” refer to a relative orientation of a set of components, such as in accordance with the drawings, but do not require a particular orientation of those components during manufacturing or use.
As used herein, the terms “connect,” “connected,” and “connection” refer to an operational coupling or linking. Connected components can be directly coupled to one another or can be indirectly coupled to one another, such as via another set of components.
As used herein, the terms “substantially” and “substantial” refer to a considerable degree or extent. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs to a close approximation, such as accounting for typical tolerance levels of the manufacturing operations described herein.
As used herein, the terms “electrically conductive” and “electrical conductivity” refer to an ability to transport an electric current. Electrically conductive materials typically correspond to those materials that exhibit little or no opposition to flow of an electric current. One measure of electrical conductivity is in terms of Siemens per meter (“S·m−1”). Typically, an electrically conductive material is one having a conductivity greater than about 104 S·m−1, such as at least about 105 S·m−1 or at least about 106 S·m−1. Electrical conductivity of a material can sometimes vary with temperature. Unless otherwise specified, electrical conductivity of a material is defined at room temperature.
Attention first turns to FIG. 1 and FIG. 2, which illustrate a semiconductor device package 100 implemented in accordance with an embodiment of the invention. In particular, FIG. 1 illustrates a perspective view of the package 100, while FIG. 2 illustrates a cross-sectional view of the package 100, taken along line A-A of FIG. 1.
In the illustrated embodiment, sides of the package 100 are substantially planar and have a substantially orthogonal orientation so as to define a lateral profile that extends around substantially an entire periphery of the package 100. Advantageously, this orthogonal lateral profile allows a reduced overall package size by reducing or minimizing a footprint area of the package 100. However, it is contemplated that the lateral profile of the package 100, in general, can be any of a number of shapes, such as curved, inclined, stepped, or roughly textured.
Referring to FIG. 2, the package 100 includes a substrate unit 102, which includes an upper surface 104, a lower surface 106, and lateral surfaces 142 and 144 disposed adjacent to sides of the substrate unit 102. In the illustrated embodiment, the lateral surfaces 142 and 144 are substantially planar and have a substantially orthogonal orientation with respect to the upper surface 104 or the lower surface 106, although it is contemplated that the shapes and orientations of the lateral surfaces 142 and 144 can vary for other implementations. The substrate unit 102 can be implemented in a number of ways, and includes electrical interconnect to provide electrical pathways between the upper surface 104 and the lower surface 106 of the substrate unit 102. The electrical interconnect can include, for example, a set of electrically conductive layers that are incorporated within a set of dielectric layers. The electrically conductive layers can be connected to one another by internal vias, and can be implemented so as to sandwich a core formed from a suitable resin, such as one based on bismaleimide and triazine or based on epoxy and polyphenylene oxide. For example, the substrate unit 102 can include a substantially slab-shaped core that is sandwiched by one set of electrically conductive layers disposed adjacent to an upper surface of the core and another set of electrically conductive layers disposed adjacent to a lower surface of the core. For certain implementations, a thickness of the substrate unit 102, namely a distance between the upper surface 104 and the lower surface 106 of the substrate unit 102, can be in the range of about 0.1 millimeter (“mm”) to about 2 mm, such as from about 0.2 mm to about 1.5 mm or from about 0.4 mm to about 0.6 mm. While not illustrated in FIG. 2, it is contemplated that a solder mask layer can be disposed adjacent to either, or both, the upper surface 104 and the lower surface 106 of the substrate unit 102.
As illustrated in FIG. 2, the substrate unit 102 includes grounding elements 118a and 118b, which are disposed adjacent to a periphery of the substrate unit 102. More particularly, the grounding elements 118a and 118b are disposed substantially at the periphery of the substrate unit 102, and are disposed adjacent to the lateral surfaces 142 and 144, respectively. The grounding elements 118a and 118b are connected to other electrical interconnect included in the substrate unit 102 and, as further described below, provide electrical pathways to reduce EMI. In the illustrated embodiment, the grounding elements 118a and 118b are implemented as grounding vias and, more particularly, as remnants of grounding vias in accordance with a set of singulation operations as further described below. Referring to FIG. 2, each of the grounding elements 118a and 118b includes an upper via pad remnant 146a or 146b, which is disposed adjacent to the upper surface 104 of the substrate unit 102, a lower via pad remnant 148a or 148b, which is disposed adjacent to the lower surface 106 of the substrate unit 102, and a plated channel remnant 150a or 150b, which extends between the upper via pad remnant 146a or 146b and the lower via pad remnant 148a or 148b. While the grounding elements 118a and 118b are illustrated as fully extending between the upper surface 104 and the lower surface 106 of the substrate unit 102, it is contemplated that the extent of the grounding elements 118a and 118b can vary for other implementations.
Still referring to FIG. 2, the grounding elements 118a and 118b include connection surfaces S1 and S2, respectively, which are lateral surfaces that face away from an interior of the package 100 and are disposed adjacent to the periphery of the substrate unit 102. More particularly, the connection surfaces S1 and S2 are electrically exposed substantially at the periphery of the substrate unit 102, and are electrically exposed adjacent to the lateral surfaces 142 and 144, respectively. In the illustrated embodiment, the connection surfaces S1 and S2 correspond to electrically exposed surfaces of the upper via pad remnants 146a and 146b, the lower via pad remnants 148a and 148b, and the plated channel remnants 150a and 150b. Advantageously, the relatively large areas of the connection surfaces S1 and S2 can enhance reliability and efficiency of electrical connections for reducing EMI. The grounding elements 118a and 118b are formed from a metal, a metal alloy, a matrix with a metal or a metal alloy dispersed therein, or another suitable electrically conductive material. For certain implementations, a height H1 of the grounding elements 118a and 118b can be substantially the same as the thickness of the substrate unit 102, and can be in the range of about 0.1 mm to about 2 mm, such as from about 0.2 mm to about 1.5 mm or from about 0.4 mm to about 0.6 mm. A width W1 of the grounding elements 118a and 118b, namely a lateral extent adjacent to the upper surface 104 or the lower surface 106, can be in the range of about 75 micrometer (“μm”) to about 275 μm, such as from about 100 μm to about 250 μm or from about 125 μm to about 225 μm.
As illustrated in FIG. 2, the package 100 also includes semiconductor devices 108a, 108b, and 108c, which are disposed adjacent to the upper surface 104 of the substrate unit 102, and electrical contacts 110a, 110b, and 110c, which are disposed adjacent to the lower surface 106 of the substrate unit 102. The semiconductor device 108b is wire-bonded to the substrate unit 102 via a set of wires 112, which are formed from gold or another suitable electrically conductive material, and the semiconductor devices 108a and 108c are surface mounted to the substrate unit 102. In the illustrated embodiment, the semiconductor device 108b is a semiconductor chip, while the semiconductor devices 108a and 108c are passive devices, such as resistors, capacitors, or inductors. The electrical contacts 110a, 110b, and 110c provide input and output electrical connections for the package 100, and at least a subset of the electrical contacts 110a, 110b and 110c are electrically connected to the semiconductor devices 108a, 108b, and 108c via electrical interconnect included in the substrate unit 102. In the illustrated embodiment, at least one of the electrical contacts 110a, 110b, and 110c is a ground electrical contact, and is electrically connected to the grounding elements 118a and 118b via electrical interconnect included in the substrate unit 102. While three semiconductor devices are illustrated in FIG. 2, it is contemplated that more or less semiconductor devices can be included for other implementations, and that semiconductor devices, in general, can be any active devices, any passive devices, or combinations thereof. It is also contemplated that the number of electrical contacts can vary from that illustrated in FIG. 2.
Still referring to FIG. 2, the package 100 also includes a package body 114 that is disposed adjacent to the upper surface 104 of the substrate unit 102. In conjunction with the substrate unit 102, the package body 114 substantially covers or encapsulates the grounding elements 118a and 118b, the semiconductor devices 108a, 108b, and 108c, and the wires 112 to provide mechanical stability as well as protection against oxidation, humidity, and other environmental conditions. The package body 114 is formed from a molding material, and includes exterior surfaces, including lateral surfaces 120 and 122 disposed adjacent to sides of the package body 114. In the illustrated embodiment, the lateral surfaces 120 and 122 are substantially planar and have a substantially orthogonal orientation with respect to the upper surface 104 or the lower surface 106, although it is contemplated that the lateral surfaces 120 and 122 can be curved, inclined, or roughly textured for other implementations. Also, the lateral surfaces 120 and 122 are substantially aligned or co-planar with the lateral surfaces 142 and 144, respectively. More particularly, this alignment is accomplished while allowing the connection surfaces S1 and S2 to be electrically exposed, such as by reducing or minimizing coverage of the connection surfaces S1 and S2 by the package body 114. For other implementations, it is contemplated that the shape of the lateral surfaces 120 and 122 and their alignment with the lateral surfaces 142 and 144 can be varied from that illustrated in FIG. 2, while allowing the connection surfaces S1 and S2 to be at least partially electrically exposed.
As illustrated in FIG. 1 and FIG. 2, the package 100 further includes an EMI shield 124 that is disposed adjacent to the exterior surfaces of the package body 114, the connection surfaces S1 and S2 of the grounding elements 118a and 118b, and the lateral surfaces 142 and 144 of the substrate unit 102. The EMI shield 124 is formed from an electrically conductive material, and substantially surrounds the semiconductor devices 108a, 108b, and 108c within the package 100 to provide protection against EMI. In the illustrated embodiment, the EMI shield 124 includes an upper portion 126 and a lateral portion 128, which extends around substantially the entire periphery of the package body 114 and defines the orthogonal lateral profile of the package 100. As illustrated in FIG. 2, the lateral portion 128 extends downwardly from the upper portion 126 and along the lateral surfaces 142 and 144 of the substrate unit 102, and includes a lower end that is substantially aligned or co-planar with the lower surface 106 of the substrate unit 102. However, it is contemplated that the extent of the lateral portion 128 and the alignment of its lower end with the lower surface 106 can be varied for other implementations.
As illustrated in FIG. 2, the EMI shield 124 is electrically connected to the connection surfaces S1 and S2 of the grounding elements 118a and 118b. When electromagnetic emissions radiated from an interior of the package 100 strike the EMI shield 124, at least a portion of these emissions can be efficiently grounded via the grounding elements 118a and 118b, thereby reducing the level of emissions that can pass through the EMI shield 124 and adversely affect neighboring semiconductor devices. Similarly, when electromagnetic emissions from a neighboring semiconductor device strike the EMI shield 124, a similar grounding can occur to reduce EMI of the semiconductor devices 108a, 108b and 108c within the package 100. During operation, the package 100 can be disposed on a printed circuit board (“PCB”) and electrically connected to the PCB via the electrical contacts 110a, 110b, and 110c. As previously described, at least one of the electrical contacts 110a, 110b, and 110c is a ground electrical contact, and the ground electrical contact can be electrically connected to a ground voltage provided by the PCB. Grounding of electromagnetic emissions incident upon the EMI shield 124 can occur through an electrical pathway including the grounding elements 118a and 118b, other electrical interconnect included in the substrate unit 102, and the ground electrical contact. Because the lower end of the EMI shield 124 is substantially aligned with the lower surface 106 of the substrate unit 102, the lower end also can be electrically connected to a ground voltage provided by the PCB, thereby providing an alternative electrical pathway for grounding undesired electromagnetic emissions. Alternatively, or in conjunction, the lower via pad remnants 148a and 148b can be electrically connected to a ground voltage provided by the PCB.
In the illustrated embodiment, the EMI shield 124 is a conformal shield that is formed as a set of layers or films. Advantageously, the EMI shield 124 can be formed adjacent to and in direct contact with all exterior of the package 100 without the use of an adhesive, thereby enhancing reliability and resistance to temperature, humidity, and other environmental conditions. Also, the conformal characteristics of the EMI shield 124 allow similar EMI shields and similar manufacturing operations to be readily applied to semiconductor device packages of different sizes and shapes, thereby reducing manufacturing cost and time to accommodate the different packages. For certain implementations, a thickness of the EMI shield 124 can be in the range of about 1 μm to about 500 μm, such as from about 1 μm to about 100 μm, from about 1 μm to about 50 μm, or from about 1 μm to about 10 μm. Such reduced thickness of the EMI shield 124, relative to a typical casing, allows a reduced overall package size, and is a further advantage of the illustrated embodiment.
Attention next turns to FIG. 3, which illustrates an enlarged, cross-sectional view of a portion of the package 100 of FIG. 1 and FIG. 2. In particular, FIG. 3 illustrates a particular implementation of the EMI shield 124 that is disposed adjacent to the package body 114.
As illustrated in FIG. 3, the EMS shield 124 is multi-layered and includes an inner layer 300, which is disposed adjacent to the package body 114, and an outer layer 302, which is disposed adjacent to the inner layer 300 and is exposed at the exterior of the package 100. In general, each of the inner layer 300 and the outer layer 302 can be formed from a metal, a metal alloy, a matrix with a metal or a metal alloy dispersed therein, or another suitable electrically conductive material. For example, each of the inner layer 300 and the outer layer 302 can be formed from aluminum, copper, chromium, tin, gold, silver, nickel, stainless steel, or a combination thereof. The inner layer 300 and the outer layer 302 can be formed from the same electrically conductive material or different electrically conductive materials. For example, a metal, such as nickel, can be selected for both the inner layer 300 and the outer layer 302. In some instances, different electrically conductive materials can be selected for the inner layer 300 and the outer layer 302 to provide complementary functionalities. For example, a metal with a higher electrical conductivity, such as aluminum, copper, gold, or silver, can be selected for the inner layer 300 to provide EMI shielding functionality. On the other hand, a metal with a somewhat lower electrical conductivity, such as nickel, can be selected for the outer layer 302 to protect the inner layer 300 against oxidation, humidity, and other environmental conditions. In this case, the outer layer 302 also can contribute to the EMI shielding functionality, while providing the protection functionality. While two layers are illustrated in FIG. 3, it is contemplated that more or less layers can be included for other implementations.
FIG. 4 illustrates a cross-sectional view of a semiconductor device package 400 implemented in accordance with another embodiment of the invention. Certain aspects of the package 400 are implemented in a similar manner as previously described for the package 100 of FIG. 1 through FIG. 3 and, thus, are not further described herein.
Referring to FIG. 4, the package 400 includes grounding elements 418a and 418b, which are disposed substantially at the periphery of the substrate unit 102. In the illustrated embodiment, the grounding elements 418a and 418b are implemented as remnants of grounding vias, and each of the grounding elements 418a and 418b includes an upper via pad remnant 446a or 446b, which is disposed adjacent to the upper surface 104 of the substrate unit 102, a lower via pad remnant 448a or 448b, which is disposed above and at a certain spacing apart from the lower surface 106 of the substrate unit 102, and a plated channel remnant 450a or 450b, which extends between the upper via pad remnant 446a or 446b and the lower via pad remnant 448a or 448b. While the grounding elements 418a and 418b are illustrated as partially extending between the upper surface 104 and the lower surface 106 of the substrate unit 102, it is contemplated that the extent of the grounding elements 418a and 418b can vary for other implementations. In the illustrated embodiment, the grounding elements 418a and 418b include connection surfaces S1′ and S2′, respectively, which are electrically exposed adjacent to the lateral surfaces 142 and 144, respectively. Advantageously, the relatively large areas of the connection surfaces S1′ and S2′ can enhance reliability and efficiency of electrical connections for reducing EMI. For certain implementations, a height H2 of the grounding elements 418a and 418b can be somewhat less than the thickness of the substrate unit 102, and can be in the range of about 0.1 mm to about 1.8 mm, such as from about 0.2 mm to about 1 mm or from about 0.3 mm to about 0.5 mm. A width W2 of the grounding elements 418a and 418b, namely a lateral extent adjacent to the upper surface 104, can be in the range of about 75 μm to about 275 μm, such as from about 100 μm to about 250 μm or from about 125 μm to about 225 μm.
As illustrated in FIG. 4, the package 400 also includes a semiconductor device 408b, which is a semiconductor chip that is disposed adjacent to the upper surface 104 of the substrate unit 102. In the illustrated embodiment, the semiconductor device 408b is flip chip-bonded to the substrate unit 102, such as via a set of solder bumps. It is contemplated that the semiconductor device 408b can be electrically connected to the substrate unit 102 in another manner, such as by wire-bonding.
FIG. 5A through FIG. 5E illustrate a method of forming a semiconductor device package, according to an embodiment of the invention. For ease of presentation, the following manufacturing operations are described with reference to the package 100 of FIG. 1 through FIG. 3. However, it is contemplated that the manufacturing operations can be similarly carried out to form other semiconductor device packages.
Referring first to FIG. 5A and FIG. 5B, a substrate 500 is provided. To enhance manufacturing throughput, the substrate 500 includes multiple substrate units, including the substrate unit 102 and an adjacent substrate unit 102′, thereby allowing certain of the manufacturing, operations to be readily performed in parallel or sequentially. The substrate 500 can be implemented in a strip manner, in which the multiple substrate units are arranged sequentially in a linear fashion, or in an array manner, in which the multiple substrate units are arranged in a two-dimensional fashion. For ease of presentation, the following manufacturing operations are primarily described with reference to the substrate unit 102 and related components, although the manufacturing operations can be similarly carried for other substrate units and related components.
As illustrated in FIG. 5A and FIG. 5B, multiple grounding vias are disposed adjacent to a periphery of each substrate unit. In particular, grounding vias 502a, 502b, 502c, 502d, and 502e are disposed adjacent to sides of the substrate unit 102. In the illustrated embodiment, each grounding via includes an upper via pad, such as an upper via pad 546a or 546b, a lower via pad, such as a lower via pad 548a or 548b, and a plated channel, such as a plated channel 550a or 550b. The grounding vias 502a, 502b, 502c, 502d, and 502e can be formed in any of a number of ways, such as photolithography, chemical etching, laser drilling, or mechanical drilling to form openings, along with plating of the openings using a metal, a metal alloy, a matrix with a metal or a metal alloy dispersed therein, or another suitable electrically conductive material. For certain implementations, an electrically conductive material can be applied to and drawn into the openings so as to substantially fill the openings with the electrically conductive material. For example, the electrically conductive material can include a metal, such as copper, a solder, such as any of a number of fusible metal alloys having melting points in the range of about 90° C. to about 450° C., or an electrically conductive adhesive, such as any of a number of resins having an electrically conductive filler dispersed therein. Filling the openings can yield larger areas for resulting connection surfaces, thereby further enhancing reliability and efficiency of electrical connections for reducing EMI.
In the illustrated embodiment, a via pad, such as the upper via pad 546a or 546b, has an annular shape, and a plated channel, such as the plated channel 550a or 550b, is shaped in the form of a circular cylinder, including a substantially circular cross-section. It is contemplated that the shapes of a via pad and a plated channel, in general, can be any of a number of shapes. For example, a plated channel can have another type of cylindrical shape, such as an elliptic cylindrical shape, a square cylindrical shape, or a rectangular cylindrical shape, or can have a non-cylindrical shape, such as a cone, a funnel, or another tapered shape. It is also contemplated that lateral boundaries of a plated channel can be curved or roughly textured. For certain implementations, a lateral extent W3 of each plated channel (also sometimes referred to as a via size) can be in the range of about 50 μm to about 350 μm, such as from about 100 μm to about 300 μm or from about 150 μm to about 250 μm, while a lateral extent W4 of each via pad (also sometimes referred to as a via pad size) can be in the range of about 150 μm to about 550 μm, such as from about 200 μm to about 500 μm or from about 250 μm to about 450 μm. If a plated channel or a via pad has a non-uniform shape, the lateral extent W3 or W4 can correspond to, for example, an average of lateral extents along orthogonal directions.
To enhance reliability and efficiency of electrical connections for reducing EMI, grounding vias are disposed adjacent to all four sides of each substrate unit, although the grounding vias also can be disposed adjacent to a subset of the four sides. It is also contemplated that grounding vias can be disposed adjacent to all four corners of each substrate unit or a subset of the four corners. For certain implementations, a spacing L1 of nearest-neighbor grounding vias of a substrate unit (also sometimes referred to as a via pitch) can be in the range of about 0.1 mm to about 3 mm, such as from about 0.2 mm to about 2 mm or from about 0.5 mm to about 1.5 mm. Referring to FIG. 5B, a dashed boundary within each substrate unit defines a “keep-out” portion, within which semiconductor devices are disposed. To reduce or minimize adverse impact on the operation of semiconductor devices, grounding vias of a substrate unit can be spaced apart from the “keep-out” portion by a spacing L2 (also sometimes referred to as a “keep-out” distance). For certain implementations, the spacing L2 can be in the range of about 50 μm to about 300 μm, such as from about 50 μm to about 200 μm or from about 100 μm to about 150 μm. It is contemplated that the number of grounding vias and their positioning within the substrate 500 can vary from that illustrated in FIG. 5A and FIG. 5B. It is also contemplated that multiple rows of grounding vias can be disposed adjacent to a periphery of each substrate unit.
Once the substrate 500 is provided, the semiconductor devices 108a, 108b, and 108c are disposed adjacent to an upper surface 504 of the substrate 500, and are electrically connected to the substrate unit 102. In particular, the semiconductor device 108b is wire-bonded to the substrate unit 102 via the wires 112, and the semiconductor devices 108a and 108c are surface mounted to the substrate unit 102. Referring to FIG. 5A, a lower surface 524 of the substrate 500 is disposed adjacent to a tape 506, which can be implemented as a single-sided or double-sided adhesive tape. Advantageously, the tape 506 secures the substrate unit 102 with respect to adjacent substrate units, and allows various subsequent operations to be carried out with those components disposed adjacent to the tape 506, without requiring inversion or transfer to a separate carrier.
Next, as illustrated in FIG. 5C, a molding material 514 is applied to the upper surface 504 of the substrate 500 so as to substantially cover or encapsulate the grounding vias 502a and 502b, the semiconductor devices 108a, 108b, and 108c, and the wires 112. The molding material 514 can include, for example, a Novolac-based resin, an epoxy-based resin, a silicone-based resin, or another suitable encapsulant. Suitable fillers also can be included, such as powdered SiO2. The molding material 514 can be applied using any of a number of molding techniques, such as compression molding, injection molding, and transfer molding. Once applied, the molding; material 514 is hardened or solidified, such as by lowering the temperature to below a melting point of the molding material 514, thereby forming a molded structure 526. To facilitate proper positioning of the substrate 500 during subsequent singulation operations, fiducial marks can be formed in the molded structure 526 such as using laser marking. Alternatively, or in conjunction, fiducial marks can be formed adjacent to a periphery of the substrate 500.
Singulation is next carried out with respect to an upper surface 516 of the molded structure 526. Such manner of singulation can be referred to as “front-side” singulation. Referring to FIG. 5C and FIG. 5D, the “front-side” singulation is carried out using a saw 518, which forms cutting slits, including cutting slits 520a and 520b. In particular, the cutting slits 520a and 520b extend downwardly and completely through the molded structure 526 and the substrate 500 and partially through the tape 506, thereby sub-dividing the molded structure 526 and the substrate 500 into discrete units, including the package body 114 and the substrate unit 102. Such manner of singulation can be referred to as “full-cut” singulation, since sub-division of the molded structure 526 and the substrate 500 at each of various locations can occur through one singulation operation, rather than multiple singulation operations, such as multiple “half-cut” singulations. Advantageously, the use of “full-cut” singulation, rather than “half-cut” singulation, enhances manufacturing throughput by reducing the number of singulation operations and the time involved for those operations. Also, manufacturing cost is reduced by enhancing an utilization ratio of the substrate 500, and an overall yield rate is enhanced by reducing the probability of defects resulting from sawing errors. As illustrated in FIG. 5D, the tape 506 secures the substrate unit 102 and the package body 114 with respect to adjacent substrate units and package bodies during the “full-cut” singulation.
Still referring to FIG. 5D, the saw 518 is laterally positioned and substantially aligned with each grounding via, such that a resulting cutting slit removes a certain volume or weight percentage of the grounding via, such as from about 10 percent to about 90 percent, from about 30 percent to about 70 percent, or from about 40 percent to about 60 percent by volume or by weight. In such manner, the grounding elements 118a and 118b are formed and include the connection surfaces S1 and S2, respectively, which are exposed to the surroundings at the periphery of the substrate unit 102. The alignment of the saw 518 during singulation can be aided by fiducial marks, which allow proper positioning of the saw 518 when forming the cutting slits 520a and 520b. For certain implementations, a width C1 of each of the cutting slits 520a and 520b (also sometimes referred to as a full-cut width or full-cut sawing street) can be in the range of about 100 μm to about 600 μm, such as from about 200 μm to about 400 μm or from about 250 μm to about 350 μm.
Next, as illustrated in FIG. 5E, an EMI coating 522 is formed adjacent to exposed surfaces, including the exterior surfaces of the package body 114, the connection surfaces S1 and S2 of the grounding elements 118a and 118b, and the lateral surfaces 142 and 144 of the substrate unit 102. The EMI coating 522 can be formed using any of a number of coating techniques, such as chemical vapor deposition, electroless plating, electrolytic plating, printing, spraying, sputtering, and vacuum deposition. For example, the EMI coating 522 can include a single layer that is formed from nickel using electroless plating and with a thickness of at least about 5 μm, such as from about 5 μm to about 50 μm or from about 5 μm to about 10 μm. If the EMI coating 522 is multi-layered, different layers can be formed using the same coating technique or different coating techniques. For example, an inner layer can be formed from copper using electroless plating, and an outer layer can be formed from nickel using either electroless plating or electrolytic plating. As another example, an inner layer (serving as a base layer) can be formed from copper using either sputtering or electroless plating and with a thickness of at least about 1 μm, such as from about 1 μm to about 50 μm or from about 1 μm to about 10 μm, and an outer layer (serving as an anti-oxidation layer) can be formed from stainless steel, nickel, or copper using sputtering and with a thickness no greater than about 1 μm, such as from about 0.01 μm to about 1 μm or from about 0.01 μm to about 0.1 μm. In these examples, surfaces to which the EMI coating 522 is applied can be subjected to certain pre-treatment operations to facilitate formation of the inner layer and the outer layer. Examples of such pre-treatment operations include surface roughening, such as by chemical etching or mechanical abrasion, and formation of a seed layer. Separating the substrate unit 102 and related components from the tape 506, such as using a pick-and-place technique, results in the package 100 including the EMI shield 124.
FIG. 6 illustrates a method of forming a semiconductor device package, according to another embodiment of the invention. For ease of presentation, the following manufacturing operations are described with reference to the package 400 of FIG. 4. However, it is contemplated that the manufacturing operations can be similarly carried out to form other semiconductor device packages. Also, certain aspects of the manufacturing operations are implemented in a similar manner as previously described for FIG. 5A through FIG. 5E and, thus, are not further described herein.
Referring to FIG. 6, a substrate 600 along with a hardened molding material 614 are disposed adjacent to a tape 606, which can be implemented as a single-sided or double-sided adhesive tape. Singulation is next carried out with respect to an upper surface 616 of the hardened molding material 614. As illustrated in FIG. 6, the singulation is carried out using a saw 618, which forms cutting slits 620a and 620b that extend downwardly and completely through the hardened molding material 614 and the substrate 600 and partially through the tape 606, thereby sub-dividing the hardened molding material 614 and the substrate 600 into discrete units, including the package body 114 and the substrate unit 102. In particular, the saw 618 is laterally positioned and substantially aligned with each grounding via, such that a resulting cutting slit sub-divides the grounding via into two grounding elements that are separated from one another and are disposed adjacent to respective substrate units. In such manner, the grounding elements 418a and 418b are formed and include the connection surfaces S1′ and S2′, respectively, which are exposed to the surroundings at the periphery of the substrate unit 102. Advantageously, the manner of singulation illustrated in FIG. 6 enhances manufacturing throughput by further reducing the number of singulation operations and the time involved for those operations, reduces manufacturing cost by further enhancing an utilization ratio of the substrate 600, and enhances an overall yield rate by further reducing the probability of defects resulting from sawing errors. For certain implementations, a via size W5 of each grounding via can be in the range of about 100 μm to about 700 μm such as from about 200 μm to about 600 μm or from about 300 μm to about 500 μm, while a via pad size W6 of each grounding via can be in the range of about 300 μm to about 1,100 μm, such as from about 400 μm to about 1,000 μm or from about 500 μm to about 900 μm. A width C2 of each of the cutting slits 620a and 620b can be substantially the same as the width C1 previously described above with reference to FIG. 5D, and can be in the range of about 100 μm to about 600 μm, such as from about 200 μm to about 400 μm or from about 250 μm to about 350 μm. However it is contemplated that the width C2 can vary for other implementations, and can be adjusted relative to the via size W5 or the via pad size W6 of a grounding via to allow its sub-division into multiple grounding elements. For example, the width C2, in general, can be represented as: C2<W5<W6.
While the invention has been described with reference to the specific embodiments thereof, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the invention as defined by the appended claims. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, method, or process to the objective, spirit and scope of the invention. All such modifications are intended to be within the scope of the claims appended hereto. In particular, while the methods disclosed herein have been described with reference to particular operations performed in a particular order, it will be understood that these operations may be combined, sub-divided, or re-ordered to form an equivalent method without departing from the teachings of the invention. Accordingly, unless specifically indicated herein, the order and grouping of the operations are not limitations of the invention.
Patent Grant
8350367
