Patent Application
20060276157
The present invention generally relates to apparatus and methods for integrally packaging antenna devices with semiconductor IC (integrated circuit) chips and, in particular, apparatus and methods for packaging IC chips with antenna devices that are integrally constructed from package frame structures, to thereby form compact integrated radio/wireless communications systems for millimeter wave applications.
To enable wireless communication between devices in network systems such as wireless PAN (personal area network), wireless LAN (local area network), wireless WAN (wide area network), cellular network systems, and other types of radio systems, the devices are equipped with receivers, transmitters, or transceivers, as well as antennas that can efficiently radiate/receive signals transmitted to/from other devices in the communication network.
With conventional radio communication systems, discrete components are individually encapsulated or individually mounted with low integration levels on printed circuit boards, packages or substrates. For example, for millimeter-wave applications, radio communication systems are typically built using expensive and bulky wave guides and/or package-level or board-level microstrip structures to provide electrical connections between semiconductor chips (RF integrated circuits) and between semiconductor chips and transmitter or receiver antennas.
In view of recent innovations in semiconductor fabrication and packaging technologies, the dimensions of radio communication systems are becoming increasing smaller and consequently, the integration of antennas with RF integrated circuits is becoming practically feasible. In this regard, exemplary embodiments of the invention are provided for integrally packaging antennas with semiconductor IC (integrated circuit) chips to provide small, compact electronic devices with highly integrated radio/wireless communications systems for millimeter wave applications. In particular, exemplary embodiments of the invention include apparatus and methods for integrally packaging IC chips together with antenna devices in compact package structures, wherein the antennas are integrally constructed are part of the package frame structures.
For example, in one exemplary embodiment of the invention, an electronic apparatus includes a package frame having an antenna that is integrally formed as part of the package frame and an IC (integrated circuit) chip mounted to the package frame. The apparatus further comprises interconnects that provide electrical connections to the IC chip and the antenna, and a package cover.
In various exemplary embodiments of the invention, the package frame may be a package lead frame (leadless or leaded), a package substrate, a package carrier, a package core, etc., which can be fabricated using known semiconductor fabrication methods to include antenna elements integrally formed as part of the package frame structure.
In one exemplary embodiment, the package cover can fully encapsulates the IC chip and package frame, or in another embodiment, the package cover can be formed to expose a portion or region of the package frame which contains the integrally formed antenna.
In other exemplary embodiments of the invention, one or more IC chips can be mounted to the package frame using flip-chip or backside mounting methods, wherein suitable electrical connections such as wire bonds, printed transmission lines, solder ball connections, etc., can be used to form the electrical connections to the IC chip(s) and antenna and between the IC chip(s) and antenna.
In yet other exemplary embodiments of the invention, transmission lines, antenna feed networks and/or impedance matching networks can be integrally formed as part of the package frame, for providing electrical connections to one or more antennas that are formed as part of the package frame.
In other exemplary embodiments of the invention, antennas can be packaged with IC chips that comprise integrated radio receiver circuits, integrated radio transmitter circuits, integrated radio transceiver circuits, and/or other supporting radio communication circuitry.
In yet other exemplary embodiments of the invention, various types of antennas may be implemented, including folded dipole antennas, dipole antennas, patch antennas, loop antennas, etc. For grounded antennas, ground planes can be formed as part of the chip package, or formed on a PCB or PWB to which the chip package is mounted.
These and other exemplary embodiments, aspects, features and advantages of the present invention will be described or become apparent from the following detailed description of exemplary embodiments, which is to be read in connection with the accompanying drawings.
Exemplary embodiments of the invention as described in detail hereafter generally include apparatus and methods for integrally packaging antenna devices and semiconductor IC chips to form electronic devices having highly-integrated, compact radio/wireless communications systems for millimeter wave applications. More specifically, exemplary embodiments of the invention include apparatus and methods for integrally packaging IC chips with antenna devices having radiating elements that are integrally constructed from one of various types of package frame structures that are commonly used for constructing chip packages. In general, package frames are those structures commonly used for constructing chip packages, which function to, e.g., provide mechanical stability to the chip package, provide chip bond sites for mechanically mounting one or more IC chips (or dies), and provide electrical lines and/or contacts that are used for making electrical connections to the IC chip(s) mounted thereto. In this regard, the term “package frame” or “package frame structure” as used herein should be broadly construed to include a broad range of various types of package structures including, but not limited to, package cores, substrates, carriers, die paddles, lead frames, etc., and other package structures that provide functions such as listed above (e.g., mechanical stability, chip mounting, electrical interface).
In particular,
The apparatus (10) further comprises an IC chip (13) (or die) that is backside mounted to the bottom surface of the package frame structure (11) using bonding material (14) (e.g., solder, epoxy, etc.). The apparatus (10) comprises other structures that are typically used for packaging IC chips such as package encapsulation (15) (or cover, lid, seal, passivation, etc.) to provide protection/insulation from the environment, package terminals (16) and wire bonds (17) and (18) for making electrical connections from bond pads on the chip (13) and/or package frame (11) to appropriate package terminals (16).
It is to be understood that the exemplary electronic apparatus depicted in
By way of specific example, state-of-the-art, low-cost packaging technologies typically use a “non-leaded” frame structure to allow the overall package body to be made very compact in size. Leadless packages, such as QFN (Quad Flat No-Lead) packages, are packages that are characterized by the provision of non-protruding leads (or pads) on the bottom of the encapsulation body for providing external electrical connections. Since the leads are non-protruding, the package body appears to be “non-leaded” and thus reduces the overall package size. A QFN package is mounted on a printed circuit board (PCB) using SMT (Surface Mount Technology), wherein the package is electrically connected to the PCB by soldering the non-protruding pads on the bottom side of the package body to appropriate bond pads on the surface of the PCB.
For purposes of illustration, exemplary methods according to the invention for packaging IC chips with antennas integrally formed as part of a package lead frame will now be discussed with reference to
An initial step of the exemplary packaging method, as depicted in
The lead-frame (40) can be fabricated using known techniques. For example, the lead-frame (40) can be constructed from a thin metallic sheet or metallic plate that is formed of metallic material such as, e.g., copper (Cu), a Cu-based alloy or other suitable conductor materials, having a thickness of about 1,000 microns, for example. The exemplary lead frame (40) pattern can be formed by etching, stamping or punching the metallic plate using known methods. In addition, the lower metallic surfaces of the metallic plate in antenna region (45) are subjected to a half-etching process, whereby the bottom surface of the antenna metallization in region (45) is etched to form a recess region (46) (or cavity region). The half-etching can be performed, for example, by placing an etch mask on the bottom surface of the lead frame (40) which exposes the metal surfaces in region (45), and applying etching material (e.g. chemical wet etch) to etch the metal and form the recess (46). In one exemplary embodiment, the recess region (46) is formed to a depth of about 500 microns. As explained below, the recess region (46) provides a well defined cavity or gap between the antenna radiating element(s) and a ground plane that is disposed on a PCB or PWB to which the integrated chip package is mounted (as will be explained below with reference to
After the lead frame (40) is constructed, the exemplary packaging method proceeds with a chip mounting process and wire bonding process to mount a chip to the lead frame (40) and make appropriate electrical connections between the mounted chip and lead frame elements. More specifically,
The IC chip (50) can be bonded to the die paddle (42) using any suitable bonding material placed between the bottom (non active) surface of the chip (50) and the surface of the die-paddle (42). Thereafter, electrical connections can be made by forming various bond wires including, e.g., bond wires (52) that make connections from the IC chip (50) to the differential inputs lines of the exemplary dipole antenna, a plurality of grounding bond wires (53) that form ground connections to the die paddle (42), and a plurality of bond wires (54) that connect to appropriate lead frame elements (44). It is to be appreciated that wire bonding methods of
A next step in the exemplary packaging method includes forming a package encapsulation to seal the IC chip (50), bond wires, etc., such as depicted in the exemplary schematic diagrams of
In one exemplary embodiment of the invention as depicted in
After forming the encapsulation layer (60), the resulting structure is subjected to a dicing process along a perimeter of the package structure to remove the surrounding metal that holds together the antenna, leads and die-paddle. For instance,
Moreover, the differential feed line (72) comprises two coplanar parallel feed lines (72a, 72b) of length, LF, that are separated by a gap, GF. The gap GF between the feed lines (72a, 72b) results in the formation of a balanced, edge-coupled stripline transmission line. The gap GF of the differential line (72) separates the first half-wavelength dipole element into the first and second quarter-wavelength elements (71a) and (71b). The impedance of the differential line (72) can be adjusted by, e.g., varying the width of the feed lines (72a, 72b) and the size of the gap GF between the feed lines (72a, 72b) as is understood by those of ordinary skill in the art.
The folded dipole antenna (71) has a length, denoted as LD, and a width denoted as WD. The parameter LD of the folded dipole antenna (71) will vary depending on the frequency of operation and the dielectric constant of the surrounding material, for example. By way of example, to provide a resonant frequency in a range of about 60 GHZ-61.5 GHz, the folded dipole antenna (71) can have dimensions of about WD=40 microns, GD=40 microns and LD=1460 microns.
It is to be understood that the chip packaging apparatus and methods discussed above are merely exemplary embodiments, and that one of ordinary skill in the art can readily envision other electronic devices that can be constructed based on the teachings herein. For instance, depending on the intended application and/or frequency of operation, various types of antennas can be integrally formed from package frame structures, including, but not limited to, dipole antennas, ring antennas, rectangular loop antennas, patch antennas, coplanar patch antennas, monopole antennas, etc. By way of example, all or a portion of the die paddle (42) depicted in
Furthermore, various types of IC chips may be integrally packaged with one or more antennas to construct electronic devices having highly-integrated, compact radio communications systems. For instance, an IC chip comprising an integrated transceiver circuit, an integrated receiver circuit, an integrated transmitter circuit, and/or other support circuitry, etc., can be packaged with one or more antennas integrally formed as part of the package frame to provide compact radio communications chips. These radio communications chips can be installed in various types of devices for wireless communication applications.
In other exemplary embodiments, a radio communications chip may be constructed with a package frame structure that comprises a plurality of integrated antennas. For example, an electronic radio communications chip can be constructed having IC receiver and transmitter chips and separate antennas—a receiving antenna and transmitting antenna—for each IC chip, which are formed as part of the package frame structure to which the chips are mounted.
In other exemplary embodiments, various types of antenna feed networks and/or impedance matching networks, such as balanced differential lines, coplanar lines, etc., can be integrally formed on the IC chips and/or package frame structures. For example, an impedance matching network (e.g., a transmission line) may be integrally formed on an IC chip or package frame structure to provide the necessary inductive/capacitive impedance matching between a device/component (e.g., power amplifier, LNA, etc.) formed on the IC chip and an antenna that is integrally formed from a package frame structure. Moreover, various types of feed networks may be implemented depending on, e.g., the impedance that is desired for the given application and/or the type of devices to which the antenna may be connected. For example, if the antenna is connected to an integrated transmitter system, the feed network will be designed to provide the proper connections and impedance matching for, e.g., a power amplifier. By way of further example, if the antenna is connected to a receiver system, the feed network may be designed to provide the proper connections and impedance matching for, e.g., an LNA (low noise amplifier).
Those of ordinary skill in the art will readily appreciate various advantages afforded by the present invention. For instance, package frame structures with integrated antennas according to exemplary embodiments of the invention can be constructed using known semiconductor fabrication and packaging techniques, thereby providing high-volume, low cost, antenna manufacturing capability. Moreover, exemplary embodiments of the invention enable formation of highly-integrated, compact radio communications systems in which antennas are integrally formed as part of a package frame structure and packaged with IC chips, thereby providing compact designs with very low loss between the transceiver and the antenna. Moreover, the use of integrated antenna/IC chip packages according to the present invention saves significant space, size, cost and weight, which is a premium for virtually any commercial or military application.
Although exemplary embodiments have been described herein with reference to the accompanying drawings for purposes of illustration, it is to be understood that the present invention is not limited to those precise embodiments, and that various other changes and modifications may be affected herein by one skilled in the art without departing from the scope of the invention.
