The present invention generally relates to power protection fuses for electronic circuits and electrical devices. More specifically, the invention relates to one or more embodiments of temperature-triggered fuse devices. Furthermore, the invention also relates to one or more embodiments of manufacturing such temperature-triggered fuse devices.
Modern electrical devices typically incorporate power-protection fuses to prevent an unexpected and/or undesirable power surge from damaging various components associated with such electrical devices. Many electrical devices operate in environments susceptible to unwanted and dangerous power surges or accidental reverse polarity input connections. If power surges (e.g. a voltage surge, a current surge, or both) are sufficiently high or prolonged beyond a negligible duration, electrical devices subject to power surges can sustain operation failure or permanent damages.
Therefore, protection against power surges have been commonly addressed by conventional power-protection fuses. Some fuses are one-time devices that may need to be replaced when activated, while other fuses are resettable. Regardless of one-time use or resettable characteristics, a conventional power-protection fuse is generally configured to monitor an operating current and/or an operating voltage of an electrical circuit connected to the conventional power-protection fuse, and is subsequently activated (i.e. blows the fuse to disconnect at least a portion of the electrical circuit, or clamps the operating voltage or current to a lower magnitude), when the operating current and/or the operating voltage exceeds or surges above a defined safe-operation threshold value. Typically, current or voltage surge above the defined safe-operation threshold value may damage, endanger, and/or overheat the electrical circuit connected to the fuse, unless the fuse is activated to disconnect the electrical circuit or to lower the operating voltage or current to a lower magnitude.
Conventional fuses that are often incorporated in integrated circuits (IC's) for power protection include transient voltage suppression (TVS) circuits, which protect IC's from accidental or undesirable high voltage spikes in the IC's. Examples of TVS circuits include electrostatic discharge (ESD) protection diodes. Conventional TVS protection circuits comprise two or more diodes, at least one of which is designed to conduct electricity temporarily in case of a high-voltage surge event. TVS circuits are typically designed to clamp the voltage to a particular voltage value during a power surge event, and are also designed to endure an accompanying current surge through the TVC circuits, thereby protecting the load which comprises integrated circuitry requiring protection from power surges.
However, some dangerous electrical device failures that result in gradual or sudden overheating of an electrical device, which may cause a deadly meltdown or explosion of the electrical device itself, cannot always be properly detected by merely monitoring the device operating voltage or current. For example, a mobile device with a malfunctioning battery or a malfunctioning charger may still exhibit a normal range of operating voltage and current levels, even as the temperature of the malfunctioning battery undergoes a thermal runaway to the point of the device meltdown or explosion. Conventional power-protection fuses that are designed to be triggered based on device voltage and/or current threshold levels alone are thus sometimes inaccurate or inappropriate for safeguarding against certain types of device malfunctions, such as device thermal runaway meltdowns or explosions.
Therefore, it may be advantageous to devise a novel electronic component structure as a novel fuse device, which enables real-time temperature-triggered circuit and device protection at a specified ambient temperature near the novel fuse device. It may also be advantageous to devise the novel fuse device as an integration-friendly component that can be easily incorporated into a variety of integrated circuits, circuit boards, and electrical device casings. Furthermore, it may also be advantageous to devise one or more novel device fabrication steps and methods for manufacturing the novel fuse device.
Summary and Abstract summarize some aspects of the present invention. Simplifications or omissions may have been made to avoid obscuring the purpose of the Summary or the Abstract. These simplifications or omissions are not intended to limit the scope of the present invention.
In one embodiment of the invention, a temperature-triggered fuse device for protection against power surges and thermal runaways in an electronic circuit is disclosed. This temperature-triggered fuse device comprises: a base substrate; a first metal pad and a second metal pad located on top of the base substrate or on a sputtered seed layer on top of the base substrate, wherein the first metal pad and the second metal pad are separated by an electrically-insulating material; a first wetting material bay located on top of the first metal pad; a second wetting material bay located on top of the second metal pad; an electrically-insulated gap positioned above the electrically-insulating material; and a solder bridge or a solder ball physically and electrically connecting the first wetting material bay and the second wetting material bay across the electrically-insulated gap, wherein the solder bridge or the solder ball is configured to break apart or melt due to a wetting force generated by the first wetting material bay and the second wetting material bay, when an ambient threshold temperature is reached in the temperature-triggered fuse device.
In another embodiment of the invention, a method for producing a temperature-triggered fuse device is disclosed. This method comprises the steps of: placing a first metal pad and a second metal pad on top of a base substrate, wherein the first metal pad and the second metal pad are separated by an electrically-insulating material; depositing a first de-wetting material coating on a portion of the first metal pad and a second de-wetting material coating on a portion of the second metal pad; depositing a first wetting material bay on a remaining portion of the first metal pad and a second wetting material bay on a remaining portion of the second metal pad; and placing a solder bridge or a solder ball across the first wetting material bay and the second wetting material bay, wherein the solder bridge or the solder ball forms a gap with the electrically-insulating material that separates the first metal pad and the second metal pad.
Yet in another embodiment of the invention, a plating manufacturing method for producing a temperature-triggered fuse device is disclosed. This plating manufacturing method comprises the steps of: sputtering a base seed layer on top of a base substrate; applying a photoresist on the base seed layer; forming patterns on the photoresist by utilizing a photomask, wherein the patterns identify a first piece of the base seed layer and a second piece of the base seed layer, which are separated by a gap; plating a first metal pad on the first piece of the base seed layer and a second metal pad on the second piece of the base seed layer; etching areas covered by the photoresist to remove corresponding underlying portions of the base seed layer; cleaning the areas and removing photoresist residues after etching; depositing a de-wetting material coating on a topmost surface; applying a passivation mask to identify metal exposure locations on the first metal pad and the second metal pad for removal of the de-wetting material coating; etching the de-wetting material coating from the metal exposure locations; cleaning the metal exposure locations; depositing a wetting bay seed layer on the topmost surface; applying a gap mask to identify the gap separating the first piece of the base seed layer and the second piece of the base seed layer for removal of a portion of the wetting bay seed layer above the gap; etching the portion of the wetting bay seed layer above the gap; applying a solder bridge mask to identify a solder bridge location; plating solder to form the solder bridge at the solder bridge location across the gap, wherein the solder bridge connects separated pieces of the wetting bay seed layer; and etching portions of the wetting bay seed layer above the de-wetting material coating.
Specific embodiments of the invention will now be described in detail with reference to the accompanying figures. Like elements in the various figures are denoted by like reference numerals for consistency.
In the following detailed description of embodiments of the invention, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to one of ordinary skill in the art that the invention may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.
The detailed description is presented largely in terms of description of shapes, configurations, and/or other symbolic representations that directly or indirectly resemble a novel chip structure and/or a manufacturing method for a temperature-triggered fuse device. These descriptions and representations are the means used by those experienced or skilled in the art to most effectively convey the substance of their work to others skilled in the art.
Reference herein to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. Furthermore, separate or alternative embodiments are not necessarily mutually exclusive of other embodiments. Moreover, the order of blocks in process flowcharts or diagrams representing one or more embodiments of the invention do not inherently indicate any particular order nor imply any limitations in the invention.
For the purpose of describing the invention, a term described herein as a “fuse” or a “fuse device” is defined as a special-purpose apparatus, which is designed to protect a circuit or another electronic component from malfunctions or damages due to undesirable power surges and/or thermal runaways. A fuse may be an integrated electronic component to an integrated circuit (IC's) or a discrete component operatively connected to IC's or other electronic components.
Moreover, for the purpose of describing the invention, a term described herein as “wetting force” is defined as a net pulling or pushing force resulting from intermolecular interactions among one or more wetting materials and a solder bridge or a solder ball at varying temperatures. In a preferred embodiment of the invention, as ambient temperature increases to a threshold temperature for activating a temperature-triggered fuse, the wetting force generated by intermolecular tensions among wetting material(s) (e.g. gold (Au), nickel gold (Ni/Au), copper gold (Cu/Au)) on a metallic substrate and a solder bridge or a solder ball, which connects a pair of wetting materials separated by an air gap, becomes sufficiently strong enough to break off the solder bridge or the solder ball.
Furthermore, for the purpose of describing the invention, a term described herein as a “solder bridge” or a “solder ball” is defined as a temperature-specific breakable electrical connection element between a first wetting material bay and a second wetting material bay. Typically, a solder bridge or a solder ball is positioned above an air gap, which is configured to contain broken solder bridge or solder ball pieces when the solder bridge or the solder ball breaks apart due to an increased wetting force at a threshold temperature.
In addition, for the purpose of describing the invention, a term described herein as “power surge” or “power surge event” is defined as a spike in voltage, current, or both. An example of a power surge is a voltage or current spike at an input terminal of an electrical device caused by an external power source, an external electrical signal, or a sudden change in environment such as lightening or ESD discharging.
One aspect of an embodiment of the present invention is providing a novel electronic component structure as a novel fuse device. The novel fuse device is configured to provide real-time temperature-triggered circuit and device protection at a specified ambient temperature near the novel fuse device.
Another aspect of an embodiment of the present invention is providing an IC integration-friendly temperature-triggered fuse device that can be easily incorporated into a variety of integrated circuits, circuit boards, and electrical device casings.
In addition, another aspect of an embodiment of the present invention is providing one or more novel device fabrication steps and methods for manufacturing a temperature-triggered fuse device.
Furthermore, a first metal pad (113) and a second metal pad (115) are positioned on top of the base substrate (101), as shown in
Continuing with
In addition, the novel temperature-triggered fuse device in accordance with the preferred embodiment of the invention also includes an electrically-insulating material (102) and an electrically-insulated gap (117) that physically separate the first metal pad (113) from the second metal pad (115). In some embodiments of the invention, the electrically-insulating material (102) may be a film made of the same chemical compound utilized for the first de-wetting material (109) and the second de-wetting material (111). In other embodiments, the electrically-insulating material (102) may be a specialized dielectric substance that is chemically distinct from other de-wetting materials in the novel temperature-triggered fuse device. In addition, the electrically-insulated gap (117) is preferably an air gap. In some other embodiments, other gasses, liquids, or solids with high electrical insulation properties may be utilized in the electrically-insulated gap (117).
Furthermore, the novel temperature-triggered fuse device also includes the solder bridge (105), which physically and electrically connects the first wetting material bay (103) and the second wetting material bay (107) across the electrically-insulated gap (117). In the preferred embodiment of the invention, the solder bridge (105) is designed to break apart, melt, and/or separate into multiple fragments when the wetting force generated by the first wetting material bay (103) and the second wetting material bay (107) is increased enough (i.e. due to a rising ambient temperature) to result in a sufficient net pulling or pushing force on the solder bridge (105) for structural breakage.
In context of the embodiment of the invention as shown in
Furthermore, in some embodiments of the invention, designing the temperature-triggered fuse device requires a calculated amount of solder volume, a calculated dimension of a solder ball or a solder bridge, a calculated size of the gap, and a calculated dimension of each wetting material bay to ensure a desirable structural disconnection at a desired threshold temperature.
In one example, a fuse designer may contemplate the following design considerations when estimating appropriate dimensions for certain components contained in the temperature-triggered fuse device:
The overlap between the solder bridge and the bay on each side of the gap: Ws
Gap width: Wg, Gap length: lg, Solder thickness of the bridge at the gap: is
Solder volume contained in the bridge structure: Vsg=(2Ws+Wg)*lg*ts
Upon melting, this volume will divide between the two bays
Thus, volume of solder on each bay: Vsg/2=(2Ws+Wg)*lg*ts/2
If Ws=50 microns, Wg=50 microns, lg=100 microns, ts=70 microns,
Then, Vsg=5.25×10{circumflex over ( )}5
If the solder ball on each bay (after melting) is to have a height of 40 microns, then the area of the bay can be estimated as:
Abay=13,125.00 square microns.
Thus, if each bay were to be a square shape, the length of each side, Lbay=114.56 microns.
Furthermore, as also shown in the top view (200) in
In a preferred embodiment of the invention, materials or compounds utilized for the formation of the wetting material bays are purposefully selected to generate a specific amount of wetting force on the solder bridge for breakage at a predefined ambient threshold temperature. For example, if a fuse designer intends to activate the novel temperature-triggered fuse device for electrical disconnection at 120 degree Celsius, then the fuse designer may specify a particular mixture of gold (Au) and nickel (Ni) for the wetting material bays to generate sufficient wetting force to break the solder bridge at or above 120 degree Celsius. Furthermore, the fuse designer may also choose to modify the dimensions (i.e. thickness, length, width, or height) of the solder bridge to enable a precise temperature-triggered fuse activation at a desired ambient threshold temperature level.
In context of the embodiment of the invention as shown in
In context of the embodiment of the invention as shown in
Moreover, as shown in
Furthermore, as shown in
Finally, as shown in
Then, as shown in
The third step (600C) of this embodiment involves depositing a de-wetting material coating on a topmost surface, and applying a passivation mask to identify metal exposure locations on the first metal pad (607) and the second metal pad (609) for removal of the de-wetting material coating. Then, the de-wetting material coating from the metal exposure locations is etched away to create a device structure that has a first piece (613) of the de-wetting material coating covering an outer perimeter of the first metal pad (607), and a second piece (615) of the de-wetting material coating covering an outer perimeter of the second metal pad (609), as shown in
Then, the fourth step (600D) of this embodiment involves depositing a wetting bay seed layer on the topmost surface of the device structure, and applying a gap mask to identify the gap separating the first piece (603A) of the base seed layer and the second piece (603B) of the base seed layer for removal of a portion of the wetting bay seed layer above the gap (611). Subsequently, the portion of the wetting bay seed layer above the gap (611) is etched away, which creates a first piece (617) of the wetting bay seed layer and a second piece (619) of the wetting bay seed layer, as shown in
The fifth step (600E) of this embodiment involves plating solder to form the solder bridge (625) at the solder bridge location across the gap (611), wherein the solder bridge (625) connects separated pieces (617, 619) of the wetting bay seed layer, as shown in
Then, a first de-wetting material coating (703) is deposited on an outer portion of the first aluminum pad, and a second de-wetting material coating (707) is deposited on an outer portion of the second aluminum pad. The first de-wetting material coating (703) and the second de-wetting material coating (707) can be made of same materials, such as polymer films. In addition, an electrically-insulating material (702) is also deposited between the first aluminum pad and the second aluminum pad, as shown in
Furthermore, as shown in
Finally, as shown in
Various embodiments of a temperature-triggered fuse device and related methods of manufacturing the device have been illustrated in
In contrast, the novel temperature-triggered fuse device disclosed in various embodiments of the present invention accurately tracks a rise in ambient temperature near the location of the fuse, and the fuse is rapidly triggered to disconnect the fuse-enabled circuitry and electronic components when the rise in ambient temperature meets or exceeds the specified ambient threshold temperature. Furthermore, a fuse designer is able to precisely define a desired ambient threshold temperature by customizing material selection and mix for the wetting material bays and by fine-tuning the dimensions of a solder bridge or a solder ball, which is utilized to connect a pair of wetting material bays.
Furthermore, the novel temperature-triggered fuse device disclosed in various embodiments of the present invention can be readily integrated into conventional IC designs, and various manufacturing steps disclosed herein for production of the novel temperature-triggered fuse device enable easy integration of this novel fuse design into many different types of IC's, discrete components, and other electronic devices.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
Number | Name | Date | Kind |
---|---|---|---|
3354282 | Batsch | Nov 1967 | A |
4344061 | Niwa | Aug 1982 | A |
6198376 | Ishikawa | Mar 2001 | B1 |
7554432 | Graf et al. | Jun 2009 | B2 |
20040070486 | Senda | Apr 2004 | A1 |
20050001710 | Mukai | Jan 2005 | A1 |
20080191832 | Tsai | Aug 2008 | A1 |
20080237884 | Hsu | Oct 2008 | A1 |
20090108983 | Darr et al. | Apr 2009 | A1 |
20100176910 | Knab | Jul 2010 | A1 |
20110051388 | Luppold | Mar 2011 | A1 |
20120255162 | Tamura | Oct 2012 | A1 |
20130234822 | Aurich | Sep 2013 | A1 |
Number | Date | Country | |
---|---|---|---|
20180315564 A1 | Nov 2018 | US |