Chip package with substrate integrated waveguide and waveguide interface

A chip package includes a chip configured to generate and/or receive a signal; a laminate substrate including a substrate integrated waveguide (SIW) for carrying the signal, the substrate integrated waveguide including a chip-to-SIW transition structure configured to couple the signal between the SIW and the chip and a SIW-to-waveguide transition structure configured to couple the signal out of the SIW or into the SIW, wherein the SIW-to-waveguide transition structure includes a waveguide aperture; and a plurality of electrical interfaces arranged about a periphery of the waveguide aperture, the plurality of electrical interfaces configured to receive the signal from the SIW-to-waveguide transition structure and output the signal from the chip package or to couple the signal to the SIW-to-waveguide transition structure and into the chip package.

BACKGROUND

In high-frequency applications, insertion loss is an important problem and metallic waveguides are often used for implementation of antennas and transmission of signals. The microwave frequency band (e.g., 300 MHz to 300 GHz), may be an example of a high-frequency application. For example, high-frequency signals may include radar signals or wireless communication signals.

In current applications, high-frequency signals are carried between a chip package and a metallic waveguide through a printed circuit board (PCB). This means that the high-frequency signals are carried between the chip package and the metallic waveguide in two steps. First, a high-frequency signal is transmitted from the chip package to transmission lines on the PCB. Second, PCB to waveguide transitions are used to transmit the high-frequency signal from the PCB to the waveguide. Transmission lines on the PCB have high insertion loss compared to the waveguide. For this reason, low-loss substrates utilizing high-performance materials suitable for high-frequency applications are used in PCB. These substrates increase the PCB cost substantially and, as a result, PCB cost becomes an important part of overall system cost.

Therefore, an improved chip package design that both reduces insertion losses and cost by eliminating the use of high-performance microwave materials in PCB may be desirable.

SUMMARY

One or more embodiments provide a chip package that includes a chip configured to generate and/or receive a signal; a laminate substrate including a substrate integrated waveguide (SIW) for carrying the signal through the chip package, the substrate integrated waveguide including a chip-to-SIW transition structure configured to couple the signal into the SIW from the chip and a SIW-to-waveguide transition structure configured to couple the signal out of the SIW, wherein the SIW-to-waveguide transition structure includes a waveguide aperture; and a plurality of electrical interfaces arranged about a periphery of the waveguide aperture, the plurality of electrical interfaces configured to receive the signal from the SIW-to-waveguide transition structure and output the signal from the chip package.

One or more embodiments provide a signal transmission system, including: a chip package and a metallic waveguide. The chip package includes a chip configured to generate and/or receive a signal; a laminate substrate including a substrate integrated waveguide (SIW) for carrying the signal through the chip package, the substrate integrated waveguide including a chip-to-SIW transition structure configured to couple the signal into the SIW from the chip and a SIW-to-waveguide transition structure configured to couple the signal out of the SIW, wherein the SIW-to-waveguide transition structure includes a waveguide aperture; and a plurality of electrical interfaces arranged about a periphery of the waveguide aperture, the plurality of electrical interfaces configured to receive the signal from the SIW-to-waveguide transition structure and output the signal from the chip package. The metallic waveguide is electrically coupled to the plurality of electrical interfaces, wherein the metallic waveguide is configured to receive the signal output from the chip package via the plurality of electrical interfaces and transmit the signal along a propagation path.

One or more embodiments provide a chip package that includes a chip configured to receive and process a signal; a laminate substrate including a substrate integrated waveguide (SIW) for carrying the signal through the chip package, the substrate integrated waveguide including a waveguide-to-SIW transition structure configured to couple the signal into the substrate integrated waveguide from a waveguide and a SIW-to-chip transition structure configured to couple the signal out of the substrate integrated waveguide into the chip, wherein the waveguide-to-SIW transition structure includes a waveguide aperture; and a plurality of electrical interfaces arranged about a periphery of the waveguide aperture, the plurality of electrical interfaces configured to receive the signal from the waveguide and couple the signal to the waveguide-to-SIW transition structure and into the substrate integrated waveguide.

DETAILED DESCRIPTION

In the following, details are set forth to provide a more thorough explanation of the exemplary embodiments. However, it will be apparent to those skilled in the art that embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form or in a schematic view rather than in detail in order to avoid obscuring the embodiments. In addition, features of the different embodiments described hereinafter may be combined with each other, unless specifically noted otherwise.

In this regard, directional terminology, such as “top”, “bottom”, “below”, “above”, “front”, “behind”, “back”, “leading”, “trailing”, etc., may be used with reference to the orientation of the figures being described. Because parts of embodiments can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope defined by the claims. The following detailed description, therefore, is not to be taken in a limiting sense. Directional terminology used in the claims may aid in defining one element's spatial or positional relation to another element or feature, without being limited to a specific orientation. For example, lateral, vertical, and overlapping spatial or positional relationships may be described in reference to another element or feature, without being limited to a specific orientation of the device as a whole.

In embodiments described herein or shown in the drawings, any direct electrical connection or coupling, i.e., any connection or coupling without additional intervening elements, may also be implemented by an indirect connection or coupling, i.e., a connection or coupling with one or more additional intervening elements, or vice versa, as long as the general purpose of the connection or coupling, for example, to transmit a certain kind of signal or to transmit a certain kind of information, is essentially maintained. Features from different embodiments may be combined to form further embodiments. For example, variations or modifications described with respect to one of the embodiments may also be applicable to other embodiments unless noted to the contrary.

The terms “substantially” and “approximately” may be used herein to account for small manufacturing tolerances (e.g., within 5%) that are deemed acceptable in the industry without departing from the aspects of the embodiments described herein. For example, a resistor with an approximate resistance value may practically have a resistance within 5% of that approximate resistance value.

In the present disclosure, expressions including ordinal numbers, such as “first”, “second”, and/or the like, may modify various elements. However, such elements are not limited by the above expressions. For example, the above expressions do not limit the sequence and/or importance of the elements. The above expressions are used merely for the purpose of distinguishing an element from the other elements. For example, a first box and a second box indicate different boxes, although both are boxes. For further example, a first element could be termed a second element, and similarly, a second element could also be termed a first element without departing from the scope of the present disclosure.

One or more embodiments relate to a chip package used in high-frequency applications that transmit high-frequency signals to a metallic waveguide used for the implementation of antennas and transmission of the high-frequency signals. Here, transmitting high-frequency signals from the chip package to a metallic waveguide is done without the use of high-performance microwave materials, particularly in a printed circuit board (PCB) or other RF circuit board/substrate between the chip package and the metallic waveguide.

The microwave frequency band (e.g., 300 MHz to 300 GHz), and specifically those used for radar signals or wireless communication signals, may be one example of a high-frequency application. The chip package, while not limited thereto, may be a radar chip package that houses a radar monolithic microwave integrated circuit (MIMIC) as the chip. It will also be appreciated that the high-frequency signals may be other types of radio frequency (RF) signals not limited to radar. For example, a chip may be an RF communications chip that generates RF communication signals, such as those used in 5G, 6G, or other communication protocols. In either case, the chip package outputs high-frequency signals to a metallic waveguide. In other words, the metallic waveguide, located external to the chip package, is electrically coupled to the chip and receives high-frequency signals therefrom. The metallic waveguide may also be a PCB waveguide and/or an antenna waveguide that transmits (emits) the high-frequency signal as a wireless signal.

FIG.1Ashows a cross-sectional diagram of a chip package100and a metallic waveguide150used for signal transmission according to one or more embodiments.FIG.1Bshows a plan view of the chip package100and the metallic waveguide150according toFIG.1A. The metallic waveguide150may be an antenna or part thereof that receives a high-frequency signal from the chip package100and transmits the signal into free space.

In this example, the chip package100is a Flip Chip Ball Grid Array (FCBGA) package that includes a semiconductor chip110configured to generate and/or receive high-frequency signals, a laminate substrate130, a housing103(e.g., molding) that encapsulates the chip110and at least a portion of the laminate substrate130, and electrical interfaces105, such as solder balls or bumps, that provide electrical connections to the chip110. Additional electrical interfaces106are provided as a subset of solder balls that are electrically coupled to and between the laminate substrate130and the waveguide (WG)150. In particular, the laminate substrate130includes a substrate integrated waveguide (SIW)131that extends between two transitions120and140. Thus, the two transitions120and140are incorporated in the chip package100. Electrical interfaces106provide an electrical path for the high-frequency signal to be output from the chip package100to be transmitted to the waveguide150.

Additionally, or alternatively, the electrical interfaces106provide an electrical path for the high-frequency signal to be input (i.e., coupled into) the chip package100from a metallic waveguide. For example, a radar MIMIC or a communications chip may have both transmit channels and receive channels. The transmit channels are connected to a transmit antenna (e.g., a metallic waveguide operable to transmit signals) and the receive channels are connected to a receive antenna (e.g., a metallic waveguide operable to receive signals). One antenna may be used for both transmission and reception by use of a multiplexing technique. Thus, the chip package100may have both transmit ports to transmit a signal generated in the chip110and receive ports to sense a signal intercepted by an antennas that is then transmitting to the chip110for processing.

In this case, the electrical path between the electrically interfaces106and the chip110is reversed in that an “output” described below may be referred to as an “input”, an “input” described below may be referred to as an “output”, “coupled in” may be reversed to mean “coupled out”, and “coupled out” may be reversed to mean “coupled in” according to the propagation direction of a high-frequency signal through the chip package100. The propagation direction of a high-frequency signal through the chip package100can be reversed in any of the embodiments described herein. Furthermore, while signals are referred to as “high-frequency”, it will be appreciated that other signals that are not high-frequency may also be transmitted through the substrate integrated waveguide131in a similar manner to the high-frequency signals described herein. The substrate integrated waveguide131has a cut-off frequency. Thus, a limitation on frequency is for a signal to have a frequency equal to or greater than the cut-off frequency of the substrate integrated waveguide131.

The substrate integrated waveguide131is formed in a dielectric substrate by densely arraying metallized posts or via-holes which connect the upper and lower metal plates of the substrate. The substrate integrated waveguide131is composed of a thin dielectric substrate covered on both faces by a metallic layer. The dielectric substrate embeds two parallel rows of metallic via-holes delimiting the wave propagation area of the high-frequency signal. The width of the substrate integrated waveguide131is the distance between its two vias rows, which is defined from center-to-center. An effective width may be used to characterize the wave propagation from an input to an output of the substrate integrated waveguide.

The input of the substrate integrated waveguide131is characterized by a chip-to-SIW transition120. The input of the substrate integrated waveguide is coupled to the chip110via a solder ball or other electrical interface and receives the high-frequency signal output by the chip110. The chip-to-SIW transition120may also provide one or more ground connections to the chip110.

The high-frequency signal received at the input of the substrate integrated waveguide at the chip-to-SIW transition120propagates through the substrate integrated waveguide to an output of the substrate integrated waveguide characterized by a SIW-to-WG transition140. The SIW-to-WG transition140includes electrical interfaces106(i.e., a subset of electrical interfaces105) that are not only electrically coupled to the waveguide150but also form a perimeter around the waveguide150that defines a waveguide aperture141. The waveguide aperture (WGA)141is an opening formed in the substrate integrated waveguide131and by the electrical interfaces106. The high-frequency signal propagates through the substrate integrated waveguide and leaves the chip package100by way of the waveguide aperture141. The electrical interfaces106are used as part of the output of the chip package100where the high-frequency signals propagate from the chip package100to the waveguide150. Thus, the signal is transmitted from chip110to the waveguide aperture141of the package100through the substrate integrated waveguide131.

If receiving the signal from the waveguide150(i.e., if the propagation direction of the high-frequency signal is reversed such that the chip is receiving the signal), the chip-to-SIW transition120may serve as a SIW-to-chip transition and the SIW-to-WG transition140may serve as a WG-to-SIW transition. The propagation path of the high-frequency signals through the chip package100may be bi-directional based on the application.

As can be seen inFIG.1B, the substrate integrated waveguide131is defined by a plurality of metal vias132. The vias132are formed in two parallel rows that extend from the chip110(i.e., from the chip-to-SIW transition120) towards the waveguide150(i.e., towards the SIW-to-WG transition140). The two rows meet at the SIW-to-WG transition140to encircle the waveguide150.

FIGS.2A-2Eare different views of the laminate substrate130including the substrate integrated waveguide131according to one or more embodiments.FIG.2Ais a side cross-sectional view of the laminate substrate130including the substrate integrated waveguide131.FIG.2Bis a front cross-sectional view of the laminate substrate130including the substrate integrated waveguide131.FIG.2Cis a plan view of the laminate substrate130at the chip-to-SIW transition120of the substrate integrated waveguide131.FIG.2Dis a side cross-sectional view of the laminate substrate130at the chip-to-SIW transition120of the substrate integrated waveguide131.FIG.2Eis a plan view of the laminate substrate130at the SIW-to-WG transition140of the substrate integrated waveguide131.

The laminate substrate130includes a stack of metal layers L1, L2, L3and L4in laminate. A prepreg layer P1(e.g., a dielectric material) is arranged between metal layers L1and L2. A dielectric core133is a dielectric substrate arranged between metal layers L2and L3. Another prepreg layer P2is arranged between metal layers L3and L4. The substrate integrated waveguide131is built between metal layers L2and L3. It includes metal layer L2as a top wall or a top metal plate, metal layer L3as a bottom wall or a bottom metal plate, and vias132that extend through the dielectric core133from metal layer L2to metal layer L3. Being a side view, one row of vias is shown inFIG.2A. InFIG.2B, two rows of vias132can be seen that form the lateral walls of the substrate integrated waveguide131. Thus, the substrate integrated waveguide131is defined by the area formed by L2, L3and the lateral walls of vias132.

The chip-to-SIW transition120of the substrate integrated waveguide131is shown inFIG.2C. The chip-to-SIW transition120is realized by a tapered coplanar waveguide134as an intermediate transmission structure for the high-frequency signals. Other types of intermediate transmission structures could also be used instead of a tapered coplanar waveguide. The chip-to-SIW transition120also includes chip RF ground line connections135that provide ground signals to the chip110and a chip RF signal line connection136that receives the high-frequency signals from the chip110. The line connections135and136are solder balls or bumps, which can be seen inFIG.2D. The tapered coplanar waveguide134receives the high-frequency signals from line connection136and transmits the high-frequency signals to the via rows such that they propagate along the via rows to the SIW-to-WG transition140.

InFIG.2D, line connections135and136are electrically coupled to metal layer L1and line connection136is further electrically coupled to metal layer L2, and thus to the substrate integrated waveguide131, by a metal via137.

FIG.2Eis a plan view of the laminate substrate130at the SIW-to-WG transition140of the substrate integrated waveguide131. The two rows of vias132encircle the waveguide aperture141that is formed in metal layers L3and L4of the laminate substrate130and is also defined by the periphery of the electrical interfaces (e.g., solder balls)106. In other words, the waveguide aperture141is a cavity that starts at metal layer L3, extends through metal layer L4, extends between electrical interfaces106, and further extends to the waveguide150. The transmitted wave of the high-frequency signal propagates through the waveguide aperture141to the waveguide150. Additionally, metal layer L3may include a metal island142within the waveguide aperture141. The metal island142may be used for impedance matching.

FIG.2Eshows two cut lines A-A and B-B illustrated inFIGS.2F and2G, respectively. Thus,FIG.2Fillustrates a cross-sectional view of the SIW-to-WG transition140of the substrate integrated waveguide131taken at cut line A-A andFIG.2Gillustrates a cross-sectional view of the SIW-to-WG transition140of the substrate integrated waveguide131taken at cut line B-B.

The stacked layers can again be seen inFIGS.2F and2G, with a row of vias132extending between metal layers L2and L3and forming the substrate integrated waveguide131. A PCB200(e.g., an antenna PCB) is also shown that is to be electrically connected to the substrate integrated waveguide131via electrical interfaces106. Specifically, waveguide aperture141may extend through a portion of the PCB200, the interior sidewalls of which are lined (i.e., metal plated), with a PCB waveguide210used to carry the signals from the package to the waveguide150(not illustrated). The PCB waveguide210may be made of copper but is not limited thereto. The PCB waveguide210of the PCB200is coupled to electrical interfaces106.

The waveguide aperture141is formed in metal layer L3, which also includes the metal island142. The waveguide aperture141extends through metal layer L4, through an area defined by the periphery of the electrical interfaces106, and through the PCB200. Thus, the PCB200is an exterior transition from the chip package100to the metal waveguides150(i.e., antennas). The high-frequency signal is output from the substrate integrated waveguide131at the waveguide aperture141and is coupled into the waveguide150by the metal island142, electrical interfaces106, and the PCB waveguide210. The metal island142in L3layer radiates the signal into the electrical interfaces106and the PCB waveguide210and the dielectric layer P2between metal layers L3and L4is very thin. If the dielectric layer P2is thicker, metal vias connecting metal layers L3and L4proximate to the waveguide aperture141may be used to transmit the signal to the electrical interfaces106and out of the package (or to couple the signal into the substrate integrated waveguide131during reception). The waveguide aperture141inside the PCB200is a hole and no high-performance material is needed inside the PCB200. Thus, the waveguide aperture141is a contiguous opening that starts at metal layer L3of the substrate integrated waveguide131and extends through the PCB200and through the metal waveguides150.

FIGS.3A-3Care cross-sectional views of a chip package coupled to a metallic waveguide150according to one or more embodiments where the location of the coupling is varied. The laminate substrate130includes a backside161, a frontside162, and lateral sides163that extend between the backside and the frontside and placement of the chip110, electrical interfaces106, and the waveguides210and150are varied relative to the backside, the frontside, and the lateral sides of the laminate substrate130.

InFIG.3A, similar to the arrangement shown inFIG.1A, the chip package100includes a chip110electrically coupled to the backside of the laminate substrate130. A frontside of the laminate substrate130is electrically coupled, via electrical interfaces106, to a PCB200. The PCB200includes metal layers205that are connected to a PCB waveguide210. The PCB waveguide210is a metal structure that lines sides of the waveguide aperture141and provides an electrical path from the electrical interfaces106to the metal waveguides150(i.e., antennas) for the high-frequency signals to propagate.

InFIG.3B, the metal waveguide150is electrically coupled to the same side of the laminate substrate130as the chip110(i.e., the backside of the laminate substrate130). In this case, the electrical interfaces106are also arranged at the backside of the laminate substrate130. Since rigid contacting structures, such as solder balls, may not be possible in this location, the electrical interfaces106may be flexible contacting structures or rigid non-contacting structures.

InFIG.3C, the metal waveguide150is electrically coupled to a lateral side of the laminate substrate130instead of the backside or the frontside. In this case, the electrical interfaces106are also arranged at the lateral side of the laminate substrate130. Since rigid contacting structures, such as solder balls, may not be possible in this location, the electrical interfaces106may be flexible contacting structures or rigid non-contacting structures.

FIGS.4A-4Care cross-sectional views of a chip package coupled to a metallic waveguide according to one or more embodiments where the location of the coupling is varied. In these figures, the chip110is electrically coupled to the frontside of the laminate substrate130instead of the backside, as was the case inFIGS.3A-3C. The arrangement of the metal waveguide150with respect to the chip package100is similar to the arrangements presented forFIGS.3A-3C.

FIGS.5A-5Care cross-sectional views of a chip package coupled to a metallic waveguide according to one or more embodiments where the location of the coupling is varied. In these figures, the chip110is integrated in the laminate substrate130instead of being coupled to the backside or to the frontside thereof, as was the case inFIGS.3A-3CandFIGS.4A-4C, respectively. The arrangement of the metal waveguide150with respect to the chip package100is similar to the arrangements presented forFIGS.3A-3C.

FIG.6is a cross-sectional view of a chip package coupled to a PCB according to one or more embodiments. The chip package100and its arrangement relative to the PCB200is similar to that shown inFIG.3A. However, in this case, the PCB200includes an additional substrate integrated waveguide300integrated therein. In particular, the metal layers205of the PCB200are used in a similar manner shown inFIG.2Ato form the additional substrate integrated waveguide300, with vias302extending between the two middle metal layers205(e.g., L2and L3) to form the additional substrate integrated waveguide300. The additional substrate integrated waveguide300receives the high-frequency signal from the PCB waveguide210and transmits the high-frequency signal along its propagation path to, for example, another device or metal waveguide. Thus, the PCB waveguide210is used to couple out the high-frequency signal from the substrate integrated waveguide131of the chip package100and couple the high-frequency signal into the additional substrate integrated waveguide300.

FIG.7is a cross-sectional view of a chip package100coupled to an antenna PCB200according to one or more embodiments. The metal waveguides150are waveguide antennas for transmitting high-frequency signals into an environment (e.g., as radar waves, communication waves, or other RF waves). The high-frequency signals are output from the chip package100by its electrical interfaces106and the PCB waveguides210is used to distribute the high-frequency signals to the metal waveguides150.

The foregoing embodiments that include integrating the SIW131and its transition structures120and140into the chip package100reduces system cost by eliminating high-performance materials from the PCB200. In addition, with SIW, the chip package100is affected less from production tolerances. In addition, system performance is expected to be higher for systems that includes waveguides for signal transmission, since the overall insertion losses should decrease.