The present disclosure relates generally to electro-optical devices and to a ribbon bonding ground plane for radio frequency performance improvement in electro-optical devices.
Electro-optical devices may include components disposed on multiple different substrates. For example, integrated circuits, optical emitters, controllers, and/or other components may be disposed on different substrates within an electro-optical device. Electrical connection between different components on different substrates may be achieved using bond wires. For example, a bond wire may connect an output of a controller to an input of an optical emitter to enable the controller to control the optical emitter. This may enable connection between the different components without manufacturing a new substrate to support the different components, thereby providing flexibility in design of electro-optical devices. Bond wires may introduce inductance at high radio frequencies. The inductance may be based on a bond wire diameter, a bond wire material, a bond wire length, a frequency of operation, a height that the bond wire reaches above one or more substrates, or a separation between pairs of bond wires, among other examples.
In some implementations, an electro-optical device includes a first substrate including a first set of ground pads and a first signal pad disposed between a first ground pad and a second ground pad of the first set of ground pads; a second substrate including a second set of ground pads and a second signal pad disposed between a third ground pad and a fourth ground pad of the second set of ground pads, wherein the first ground pad is aligned to the third ground pad to form a first ground pad pair, the second ground pad is aligned to the fourth ground pad to form a second ground pad pair, and the first signal pad is aligned to the second signal pad to form a signal pad pair; a set of wire bondings including a first wire bonding connecting the first ground pad pair, a second wire bonding connecting the second ground pad pair, and a third wire bonding connecting the first signal pad and the second signal pad; an optical emitter associated with the first substrate and electrically connected to an electrical signal component associated with the second substrate via the third wire bonding; and a planar ribbon bonding connecting the first ground pad to the fourth ground pad, wherein the planar ribbon bonding crosses the third wire bonding without contacting the third wire bonding.
In some implementations, an electro-optical device includes an optical emitter disposed on a first substrate; and a signal controller for the optical emitter disposed on a second substrate, wherein the first substrate and the second substrate include at least one ground pad pair connected by a corresponding at least one ground pad wire bonding, wherein the first substrate and the second substrate include at least one signal pad pair connected by a corresponding at least one signal pad wire bonding and electrically connecting the optical emitter to the signal controller, and wherein the first substrate and the second substrate are connected by at least one planar ribbon bonding from at least one first ground of the first substrate to at least one second ground of the second substrate such that the at least one planar ribbon bonding crosses the at least one signal pad wire bonding.
In some implementations, an electro-optical device includes a first substrate including a first ground pad and a first signal pad; a second substrate including a second ground pad and a second signal pad, wherein the first signal pad and the second signal pad form a signal pad pair, wherein the first substrate is separated from the second substrate by less than a threshold amount; wherein the first substrate is configured to receive an optical component and the second substrate is configured to receive an electrical component that is couplable to the optical component via a wire bonding between the first signal pad and the second signal pad; and a planar ribbon bonding connecting the first ground pad to the second ground pad and diagonally crossing the wire bonding.
The following detailed description of example implementations refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements.
Bond wires connecting electro-optical components disposed on different substrates can induce inductance when used for high radio frequency (RF) operations. This inductance, which may be referred to as “parasitic inductance” can be reduced by minimizing a separation between the substrates, thereby reducing a length of the bond wires, which may also be referred to as “wire bondings.” For example, a first substrate, onto which a first component is attached, may be coplanar with a second substrate, onto which a second component is attached, and a wire bonding may cross a gap between the first and second substrate. In some examples, the wire bonding may extend both vertically and laterally. In other words, rather than a wire bonding being coplanar with the substrates, the wire bonding may extend up above a surface of the substrates (and components thereon) forming an arched or rectangular profile or cross-section.
Reduction of the parasitic inductance can be achieved by disposing a ground plane below the wire bonding. For example, a grounded metal layer may be disposed coplanar with and between a first substrate and a second substrate and a wire bonding may extend upward from the first substrate and the second substrate above the ground plane. However, to attach the ground plane layer to, for example, grounded pads of the first substrate and the second substrate, the first substrate and the second substrate may have additional separation, which may extend a length of the wire bonding. Additionally, or alternatively, a shim may be attached between the substrates with a conductive epoxy or a welding connection to enable manufacture of the ground plane layer. However, adding a shim and a conductive connection may add manufacturing complexity and make high volume manufacturing difficult.
Rather than a monolithic grounding layer, a grounding ribbon can be disposed under the wire bond to reduce parasitic inductance. For example, the grounding ribbon and the wire bonding are colinear between the first substrate and the second substrate. Because the grounding ribbon is wider than the wire bonding, the grounding ribbon forms a grounding plane beneath the wire bonding. However, positioning a grounding ribbon colinear with a wire bonding results in additional separation between the substrates which increases parasitic inductance. This may reduce a benefit (e.g., an amount of parasitic inductance reduction) that is achieved by disposing the grounding ribbon under the wire bond.
Some implementations described herein provide a ribbon bonding ground plane that is not colinear with a wire bonding. For example, the ribbon bonding may extend from a first ground pad on a first substrate and on a first side of a wire bonding to a second ground pad on a second substrate and on a second side of the wire bonding. In this case, the ribbon bonding crosses the wire bonding rather than being colinear with the wire bonding. Based on the ribbon bonding crossing the wire bonding a separation between the first substrate and the second substrate can be reduced relative to a colinear ribbon bonding, thereby reducing a length of the wire bonding. Based on reducing a length of the wire bonding and the ribbon bonding providing a ground plane for the wire bonding, implementations described herein reduce parasitic inductance relative to other techniques for connecting multiple substrates for high RF operations.
In some implementations, first substrate 110 may be coplanar with second substrate 120. For example, first substrate 110 and second substrate 120 may have approximately coplanar surfaces onto which approximately coplanar bond pads are disposed (e.g., the ground pads and the signal pads). In some implementations, first substrate 110 may be separated from second substrate 120 by less than a threshold amount. For example, based at least in part on using a crossing ribbon connector rather than a colinear ribbon connector, as described in more detail herein, a separation between first substrate 110 and second substrate 120 may be less than 400 micrometers (μm), less than 200 μm, less than 100 μm, less than 50 μm, less than 25 μm, less than 10 μm, or less than 5 μm, among other examples.
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In some implementations, ribbon bonding 140 may have a particular structure and/or a particular material. For example, ribbon bonding 140 may be a flexible ribbon connector that includes a metallic material. In some implementations, ribbon bonding 140 may include a cladding material (e.g., a dielectric material or an insulator material). Additionally, or alternatively, ribbon bonding 140 may be a rigid ribbon connector. In some implementations, ribbon bonding 140 is non-insulated. For example, ribbon bonding 140 may be formed from bare ribbon wire. In this case, ribbon bonding 140 may have an air gap (or other non-conductive medium gap, such as another gas) separating ribbon bonding 140 from wire bonding 130-3. Alternatively, ribbon bonding 140 may be insulated. For example, ribbon bonding 140 may be a ribbon connector coated with an insulative material. In this case, the insulated material may prevent ribbon bonding 140 from touching wire bonding 130-3, thereby enabling ribbon bonding 140 to be positioned closer to wire bonding 130-3 (e.g., without risk of electrically grounding wire bonding 130-3 as a result of accidental touching) and further reduce parasitic inductance (e.g., by being positioned closer together).
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The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the implementations to the precise forms disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the implementations. Furthermore, any of the implementations described herein may be combined unless the foregoing disclosure expressly provides a reason that one or more implementations may not be combined.
As used herein, satisfying a threshold may, depending on the context, refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, or the like.
Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of various implementations. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various implementations includes each dependent claim in combination with every other claim in the claim set. As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiple of the same item.
No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Further, as used herein, the article “the” is intended to include one or more items referenced in connection with the article “the” and may be used interchangeably with “the one or more.” Furthermore, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, or a combination of related and unrelated items), and may be used interchangeably with “one or more.” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Also, as used herein, the term “or” is intended to be inclusive when used in a series and may be used interchangeably with “and/or,” unless explicitly stated otherwise (e.g., if used in combination with “either” or “only one of”). Further, spatially relative terms, such as “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the apparatus, device, and/or element in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.
This patent application claims priority to U.S. Provisional Patent Application No. 63/355,366, filed on Jun. 24, 2022, and entitled “WIRE BONDING INTERCONNECTION BETWEEN COPLANAR STRUCTURES.” The disclosure of the prior application is considered part of and is incorporated by reference into this patent application.
Number | Date | Country | |
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63355366 | Jun 2022 | US |