A typical microelectronic package includes at least one microelectronic die that is mounted on a substrate such that bond pads on the microelectronic die are attached directly to corresponding bond lands on the substrate using reflowable solder materials.
The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. It is understood that the accompanying drawings depict only several embodiments in accordance with the present disclosure and are, therefore, not to be considered limiting of its scope. The disclosure will be described with additional specificity and detail through use of the accompanying drawings, such that the advantages of the present disclosure can be more readily ascertained, in which:
In the following detailed description, reference is made to the accompanying drawings that show, by way of illustration, specific embodiments in which the claimed subject matter may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the subject matter. It is to be understood that the various embodiments, although different, are not necessarily mutually exclusive. For example, a particular feature, structure, or characteristic described herein, in connection with one embodiment, may be implemented within other embodiments without departing from the spirit and scope of the claimed subject matter. In addition, it is to be understood that the location or arrangement of individual elements within each disclosed embodiment may be modified without departing from the spirit and scope of the claimed subject matter. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the subject matter is defined only by the appended claims, appropriately interpreted, along with the full range of equivalents to which the appended claims are entitled. In the drawings, like numerals refer to the same or similar elements or functionality throughout the several views, and that elements depicted therein are not necessarily to scale with one another, rather individual elements may be enlarged or reduced in order to more easily comprehend the elements in the context of the present description.
Embodiments of the present description relate to the field of fabricating microelectronic packages, wherein a magnetic particle attachment material comprising magnetic particles distributed within a carrier material may be used to achieve attachment between microelectronic components. The magnetic particle attachment material may be exposed to a magnetic field, which, through the vibration of the magnetic particles within the magnetic particle attachment material, can heat a solder material to a reflow temperature for attaching microelectronic components of the microelectronic package.
In the production of microelectronic packages, microelectronic dice are generally mounted on substrates that may, in turn, be mounted to boards, which provide electrical communication routes between the microelectronic dice and external components. A microelectronic die, such as a microprocessor, a chipset, a graphics device, a wireless device, a memory device, an application specific integrated circuit, or the like, may be attached to a substrate, such as an interposer, a motherboard, and the like, through a plurality of interconnects, such as reflowable solder bumps or balls, in a configuration generally known as a flip-chip or controlled collapse chip connection (“C4”) configuration. When the microelectronic die is attached to the substrate with interconnects made of solder, the solder is reflowed (i.e. heated) to secure the solder between the microelectronic die bond pads and the substrate bond pads.
During such an attachment, a thermal expansion mismatch may occur between the microelectronic die and the substrate as the solder is heated to a reflow temperature and subsequently cooled after the attachment. This thermal expansion mismatch can warp the microelectronic package, as well as result in significant yield losses and failures due to, for example, stretched joint formation, solder bump cracking, under bump metallization failures, edge failures, and layer separation within the substrates and microelectronic dice, as will be understood to those skilled in the art.
An outer dielectric layer 112 may be formed adjacent the substrate 102 and the substrate bond pads 104. The outer dielectric layer 112 may be a solder resist material, including but not limited to epoxy and epoxy-acrylate resins. The substrate 102, substrate bond pad 104, and the outer dielectric layer 112 may be formed by any known techniques, as will be understood by those skilled in the art.
At least one solder interconnect bump 114 can be formed through an opening in the outer dielectric material 112, by any known techniques, including but not limited to printing. The solder interconnect bumps 114 may be any appropriate material, including but not limited to lead/tin alloys, such as tin/lead solder, such as 63% tin/37% lead solder, or lead-free solders, such a pure tin or high tin content alloys (e.g. 90% or more tin), such as tin/bismuth, eutectic tin/silver, ternary tin/silver/copper, eutectic tin/copper, and similar alloys.
A magnetic particle attachment material 116 may be deposited adjacent to the solder interconnect bumps 114. As shown in
The magnetic particle attachment material 116 may comprise magnetic particles 124 dispersed in a carrier material 126. The carrier material 126 may be an appropriate material, including but not limited to solvents, such as poly-ethylene glycol, and/or water, in combination with a surfactant, such as oleic acid. In one embodiment, the carrier material 126 may contain at least one flux material which may include, but is not limited to, ammonium chloride, rosin, organic acids and/or amines, and inorganic acids and/or amines. Flux materials may improve electrical connection and may improve mechanical strength of subsequent interconnect formation (as will be discussed) by chemically removing oxides and residue on the solder interconnect bumps 114. It is understood that the magnetic particles 124 may be treated with silane coupling agents and/or thiol groups for effective dispersion within the flux material. It is also understood that, depending on the selection of interconnect bump 114 material, such flux-type materials may not be necessary, and inert carriers may be used.
The magnetic particles 124 may include, but are not limited to, iron (Fe), cobalt (Co), nickel (Ni), and their respective alloys. Examples may also include ferrites and oxides containing magnetic metals. In one embodiment, the magnetic particles may be MFe2O4, where M may be any metal and O is oxygen. In another embodiment, the magnetic particles may be BaFe12O17, where Ba is barium. In yet another embodiment, the magnetic particles may comprise an iron/cobalt alloy. In certain embodiments, the magnetic particles may include a coating such as a conformal tin (Sn)/tin-based alloy/copper (Cu) layer formed, for example, by a deposition procedure, such as sputtering.
In one embodiment, the magnetic particle attachment material 116 may contain between about 1% and 99% by weight of magnetic particles 124. In a more specific embodiment, the magnetic particle attachment material 116 may contain between about 1% and 10% by weight of magnetic particles 124. In another embodiment, the magnetic particle attachment material 116 may have magnetic particles 124 sized between about 5 nm and 100 nm in length. In general, the content of magnetic particles 124 within the carrier material 126 should be sufficiently high enough to allow for efficient heating (as will be discussed), but sufficiently low enough to allow for uniform dispensation. This will, of course, depend on the size and type of magnetic particles 124 used, the characteristics of the carrier material 126, such as the viscosity, and the method of applying the magnetic particle attachment material 116.
The magnetic particle attachment material 116 may be used to attach microelectronic devices or components to one another. As shown in
A magnetic field generator 132, as also shown in
As shown in
Since heating the solder interconnect bumps 114 to a reflow temperature during attachment to the microelectronic device 134 is localized proximate the magnetic particle attachment material 116, other components (layer, traces, and the like) in the substrate are only minimally heated up relative to external heating techniques. Thus, the magnetic heating of the present disclosure may minimize stresses due to thermal expansion mismatch.
It is understood that the microelectronic device attachment structure is not limited to microelectronic device attachment projections 136, as shown but may be other attachments structures, such as contact lands 138 (either recessed, flush, or projected), as shown in
Although the described embodiments within this description are directed to the substrate 102 and the microelectronic device 134, it is understood that the concepts apply equally to any microelectronic packaging process, including but not limited to First Level Interconnects (FLI) where microelectronic dice are attached to substrates or interposers, to Second Level Interconnects (SLI) where substrates or interposers are attached to a board or a motherboard, and to Direct Chip Attach (DCA) where microelectronic dice are attached directly to a board or a motherboard.
Another embodiment of the subject matter of the present description is shown in
Once the magnetic particle attachment material 116 is deposited on the solder interconnect bumps 114, the magnetic field generator 132 may be placed proximate the substrate 102, as shown in
The magnetic particle attachment material 116 may also be placed on the microelectronic device attachment projections 136, rather than being placed on the solder interconnect bumps 114. As shown in
As shown in
In another embodiment, the solder interconnect bumps may be immersed in the magnetic particle attachment material 116 within the reservoir 148, as shown in
Although the illustrated embodiments show that magnetic particle attachment material 116 is applied to either the solder interconnect bumps 114 or the microelectronic device attachment projections 136, it is understood that the magnetic particle attachment material 116 could be applied to both.
Furthermore, it is understood that the magnetic particle attachment material 116 could be used to attach a solder material of a first component to a solder attachment structure of a second component. In one embodiment, as shown in
It is also understood that the subject matter of the present description is not necessarily limited to specific applications illustrated in
Thus, it can be considered that the integrated heat spreader attachment surface 162 may be an attachment surface of a second component (i.e. the integrated heat spreader) and that the solder thermal interface material 168 may be a solder material of a first component (i.e. the microelectronic device 134). It can be further considered that the microelectronic device back surface 168 may be an attachment surface of a second component (i.e. the microelectronic device) and that the solder thermal interface material 168 may be a solder material of a first component (i.e. the integrated heat spreader).
An embodiment of a process of the present description is illustrated in
The detailed description has described various embodiments of the devices and/or processes through the use of illustrations, block diagrams, flowcharts, and/or examples. Insofar as such illustrations, block diagrams, flowcharts, and/or examples contain one or more functions and/or operations, it will be understood by those skilled in the art that each function and/or operation within each illustration, block diagram, flowchart, and/or example can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof.
The described subject matter sometimes illustrates different components contained within, or connected with, different other components. It is understood that such illustrations are merely exemplary, and that many alternate structures can be implemented to achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Thus, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of structures or intermediate components. Likewise, any two components so associated can also be viewed as being “operably connected”, or “operably coupled”, to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being “operably couplable”, to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically mateable and/or physically interacting components and/or wirelessly interactable and/or wirelessly interacting components and/or logically interacting and/or logically interactable components.
It will be understood by those skilled in the art that terms used herein, and especially in the appended claims are generally intended as “open” terms. In general, the terms “including” or “includes” should be interpreted as “including but not limited to” or “includes but is not limited to”, respectively. Additionally, the term “having” should be interpreted as “having at least”.
The use of plural and/or singular terms within the detailed description can be translated from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or the application.
It will be further understood by those skilled in the art that if an indication of the number of elements is used in a claim, the intent for the claim to be so limited will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. Additionally, if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean “at least” the recited number.
The use of the terms “an embodiment,” “one embodiment,” “some embodiments,” “another embodiment,” or “other embodiments” in the specification may mean that a particular feature, structure, or characteristic described in connection with one or more embodiments may be included in at least some embodiments, but not necessarily in all embodiments. The various uses of the terms “an embodiment,” “one embodiment,” “another embodiment,” or “other embodiments” in the detailed description are not necessarily all referring to the same embodiments.
While certain exemplary techniques have been described and shown herein using various methods and systems, it should be understood by those skilled in the art that various other modifications may be made, and equivalents may be substituted, without departing from claimed subject matter or spirit thereof. Additionally, many modifications may be made to adapt a particular situation to the teachings of claimed subject matter without departing from the central concept described herein. Therefore, it is intended that claimed subject matter not be limited to the particular examples disclosed, but that such claimed subject matter also may include all implementations falling within the scope of the appended claims, and equivalents thereof.