PATENT DOCUMENT

Publication Number: US-9884369-B2
Application Number: US-201414577723-A
Country: US
Kind Code: B2

Title: Solid state deposition methods, apparatuses, and products

Abstract:
The described embodiments relate generally to methods for forming structures by solid state deposition processes. More specifically a method for depositing cold spray over a removable body is disclosed. Methods are also disclosed for affixing operational and structural components to a surface of a device housing with cold spray.

Claims:
What is claimed is: 
     
       1. A method for forming a metallic structure on a substrate having protruding members, the method comprising:
 forming a metallic layer by using a solid-state deposition process to spray metallic particles over the protruding members and over a sacrificial body having a volume that is positioned between the protruding members; 
 forming the metallic structure by shaping an outer surface of the metallic layer using a machining process; and 
 forming a void defined by the metallic structure, the protruding members, and the substrate by reducing the volume of the sacrificial body. 
 
     
     
       2. The method as recited in  claim 1 , wherein the volume of the sacrificial body is generally unchanged during the shaping of the outer surface of the metallic layer. 
     
     
       3. The method of  claim 1 , wherein top and side surfaces of the protruding members are covered by the metallic structure. 
     
     
       4. The method of  claim 1 , wherein the volume of the sacrificial body is reduced by using at least one of dissolving the sacrificial body or melting the sacrificial body. 
     
     
       5. The method of  claim 3 , wherein the top and side surfaces of the protruding members are unaltered during the shaping of the outer surface. 
     
     
       6. The method of  claim 1 , wherein a void volume corresponds to at least an amount of reduction of the volume of the sacrificial body. 
     
     
       7. The method of  claim 1 , wherein the sacrificial body has a higher melting point than a temperature at which the metallic particles are sprayed. 
     
     
       8. The method of  claim 1 , wherein, during spraying the metallic particles, the sacrificial body includes an indentation characterized as having a rib structure that is at least partially filled with the metallic particles such that upon altering the sacrificial body, the metallic particles within the indentation form a corresponding rib structure. 
     
     
       9. The method of  claim 1 , wherein at least a portion of the sacrificial body includes material having a lower melting point than a melting point of the metallic layer. 
     
     
       10. A method of electrically isolating an electrical component within a metallic structure, the method comprising:
 forming the metallic structure by using a solid-state deposition process to deposit metallic particles over protruding members that are included on a substrate and over a sacrificial body positioned between the protruding members, wherein an electrical component is secured to the substrate and embedded within the sacrificial body, and the metallic particles act as a conductive shield that inhibits electromagnetic energy from passing through the metallic structure to interfere with the electrical component; 
 shaping an outer surface of the metallic structure by using a machining process; and 
 forming a void defined by the metallic structure, the protruding members, and the substrate by altering the sacrificial body such as to reduce a volume of the sacrificial body, wherein the electrical component remains secured to the substrate and within the void subsequent to forming the void. 
 
     
     
       11. The method of  claim 10 , wherein the metallic structure is a structural rib. 
     
     
       12. The method of  claim 10 , wherein altering of the sacrificial body comprises heating the sacrificial body to a first melting temperature that is less than a second melting temperature associated with the metallic structure. 
     
     
       13. The method of  claim 10 , wherein the metallic structure includes at least one opening configured to allow passage of RF energy through the metallic structure. 
     
     
       14. The method of  claim 10 , wherein the metallic structure covers top and side surfaces of the protruding members.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Application Ser. No. 61/947,284 filed Mar. 3, 2014 entitled “Solid-State Deposition Methods, Apparatuses, And Products”, which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     This paper describes various embodiments that relate to using solid state deposition (also referred to as cold spray) in manufacturing. Solid state deposition methods, apparatuses, and systems can also be used to provide structures not easily provided using conventional techniques. In particular, solid state deposition processes can be used to accomplish any of the following: create layered structures within which operational components can be disposed; join two components formed of differing materials; form a part completely from cold spray materials; form a light weight structural rib; couple components to a housing without adhesive; and form a substantially sealed cavity operable as an EMI shield or audio volume. 
     BACKGROUND 
     Electronic devices may include several aesthetic features, particularly on exterior surfaces. These features may be formed by various methods. However, during a manufacturing process the exterior surfaces may be damaged during the formation of other parts or features. Also, electronic devices may include various internal features that may become decoupled, even when an adhesive is used. 
     SUMMARY 
     In one aspect, a method for forming a void having a defined size and shape within a metallic structure is described. The method may include spraying several discrete metallic particles on at least a portion of a sacrificial body having the defined size and shape. In some embodiments, at least some of the several discrete metallic particles join together subsequent to the spraying to form a metallic layer that includes the joined metallic particles. The method may further include forming the void having the defined size and shape within the metallic layer by removing the sacrificial body in a manner that an external surface of the metallic layer remains essentially undisturbed. The method may further include altering a portion of an external surface of the metallic layer to form the metallic structure. 
     In another aspect, a method of electrically isolating an electrical component is described. The method may include forming a layer of metal comprising a plurality of discrete metallic particles joined together covering at least a portion of a sacrificial body that carries the electrical component. In some embodiments, at least a portion of the layer of metal acts as a conductive shield that inhibits passage of electromagnetic energy. The method may further include removing the sacrificial body in a manner that leaves the electrical component substantially unaffected and the conductive shield undisturbed. 
     In another aspect, an electronic device is described. The electronic device may include a housing. The electronic device may further include a component assembly carried by the housing. The component assembly may include an enclosure formed of a solid state deposition layer including several discrete metallic particles joined together that form a corresponding metallic layer having identifiable joined regions that encloses and defines an internal volume. The component assembly may further include a component at least partially disposed within the internal volume. 
     In some cases, a removable body can be formed into complex shapes using low melt material such as plastic that can then be embedded within an enclosure using a solid state deposition process. In this way, complex internal shapes having features (such as undercuts) that can be difficult to create can nonetheless be formed within an enclosure without resorting to complex machining operations. 
     In some cases, thermal paths within the walls on an enclosure can be formed. The thermal paths can be formed of thermally conductive material (that may or may not also be electrically conductive). The thermally conductive paths can be used to transport heat from a heat source (such as an operational component) and a heat sink (such as a fin stack). 
     In some cases, cavities can be formed within the walls of an enclosure. The cavities can be formed using a removable body approach. The cavities can be used in many ways. For example, the cavities can be used to reduce an overall weight of the enclosure without seriously affecting the overall strength. Further, the cavities can take on stress-distributing shapes (such as a honeycomb or ribs) that can be used to evenly distribute loads applied to the housing. In some cases, the cavities can be used as acoustic volumes for enhancing audio performance of a speaker or other type audio transducer. 
     Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the described embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The described embodiments may be better understood by reference to the following description and the accompanying drawings. Additionally, advantages of the described embodiments may be better understood by reference to the following description and accompanying drawings in which: 
         FIG. 1  illustrates a simplified representation of a cold spray process, in accordance with the described embodiments of the present disclosure; 
         FIG. 2A  illustrates an embodiment of a first part and a second part in contact at a planar interface; 
         FIG. 2B  illustrates the embodiment of the part of  FIG. 2A  joined at the planar interface by a solid state deposition operation; 
         FIG. 3  illustrates a perspective view of an embodiment of a five-sided box reinforced by a cold spray operation; 
         FIGS. 4A-4E  illustrate a series of steps for securing a boss to a housing with a cold spray operation, in accordance with the described embodiments; 
         FIGS. 5A-5C  illustrate steps for forming a part from solid state deposition materials formed on a substrate, in accordance with the described embodiments; 
         FIG. 6A-6C  illustrate an embodiment in which a groove is filled with two different materials by sequential solid state deposition operations, in accordance with the described embodiments; 
         FIGS. 7A-7C  illustrate how a cavity having a specific size and dimensions can be formed by melting a removable body subsequent to a cold spray operation, in accordance with the described embodiments; 
         FIGS. 8A-8B  illustrate how a hollow structure can be formed by solid state deposition, in accordance with the described embodiments; 
         FIG. 9A-9D  illustrate formation of an assembly with a component embedded within layers of solid state deposition, in accordance with the described embodiments; 
         FIGS. 10A-10D  illustrate steps for forming a multi-layer assembly, each of the layers having varied material properties, in accordance with the described embodiments; 
         FIGS. 11A-11D  illustrate a number of steps for securing a clutch element to a device housing, in accordance with the described embodiments; 
         FIGS. 12A-12D  illustrate various embodiments in which a stiffener or bracket can be cold sprayed directly to a device housing to provide structural support to the device housing; 
         FIGS. 13A-13I  illustrate various methods for forming a reinforcement band for an IO port, in accordance with the described embodiments; 
         FIGS. 14A-14F  illustrate various methods for forming a structure along a sidewall portion of a device housing; 
         FIG. 14G  illustrate a truss structure formed by a solid state deposition operation, in accordance with the described embodiments; 
         FIGS. 15A-15F  illustrate steps for forming a hollow structure defining a front volume for an audio component, in accordance with the described embodiments; 
         FIG. 16  illustrates a device foot formed by a solid state deposition operation, in accordance with the described embodiments; 
         FIG. 17  illustrates a flowchart representing a method for forming a hollow structure, in accordance with the described embodiments; 
         FIG. 18  illustrates a side view of a substrate having a channel formed within the substrate, in accordance with the described embodiments; 
         FIG. 19  illustrates the embodiment of the substrate shown in  FIG. 18 , with a second layer applied to the first layer; 
         FIG. 20  illustrates the embodiment of the substrate shown in  FIG. 18 , with the third layer applied to the second layer; 
         FIG. 21  illustrates an isometric view of a substrate having a channel formed within the substrate, in accordance with the described embodiments; 
         FIG. 22  illustrates a cross sectional view of the embodiment of the substrate shown in  FIG. 21  taken along the  22 - 22  line, with the channel filled with a first layer and a second layer; 
         FIG. 23  illustrates the cross sectional view of the embodiment of the substrate shown in  FIG. 22  shortly after the second layer is applied over the first layer; 
         FIG. 24  illustrates a side view of an embodiment of a substrate having a channel having a first sidewall and a second sidewall formed at an angle; 
         FIG. 25  illustrates a side view of an alternate embodiment of a substrate having a channel having a first sidewall and a second sidewall formed at an angle greater than the angle shown in  FIG. 24 ; 
         FIG. 26  illustrates a side view of an alternate embodiment of a substrate having s channel having s first sidewall and a second sidewall formed at an angle greater than the angle shown in  FIG. 25 ; 
         FIG. 27  illustrates an embodiment of a substrate undergoing a solid state deposition process to form a first layer on the substrate; 
         FIG. 28  illustrates the embodiment of the substrate shown in  FIG. 27 , with the solid state deposition process forming a first layer having a relatively flat or level surface on the substrate; 
         FIG. 29  illustrates the embodiment of the substrate shown in  FIG. 28 , with the substrate undergoing a second solid state deposition process to form a second layer over a portion of the first layer; 
         FIG. 30  illustrates the embodiment of the substrate shown in  FIG. 28 , with the first layer having a rough, unsmooth surface; and 
         FIG. 31  illustrates the embodiment of the substrate shown in  FIG. 30 , with the second layer applied over the first layer. 
     
    
    
     Those skilled in the art will appreciate and understand that, according to common practice, various features of the drawings discussed below are not necessarily drawn to scale, and that dimensions of various features and elements of the drawings may be expanded or reduced to more clearly illustrate the embodiments of the present invention described herein. 
     DETAILED DESCRIPTION OF SELECTED EMBODIMENTS 
     Representative applications of methods and apparatuses according to the present application are described in this section. These examples are being provided solely to add context and aid in the understanding of the described embodiments. It will thus be apparent to one skilled in the art that the described embodiments may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order to avoid unnecessarily obscuring the described embodiments. Other applications are possible, such that the following examples should not be taken as limiting. 
     In the following detailed description, references are made to the accompanying drawings, which form a part of the description and in which are shown, by way of illustration, specific embodiments in accordance with the described embodiments. Although these embodiments are described in sufficient detail to enable one skilled in the art to practice the described embodiments, it is understood that these examples are not limiting; such that other embodiments may be used, and changes may be made without departing from the spirit and scope of the described embodiments. These and other embodiments are discussed below. However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes only and should not be construed as limiting. 
     Solid state deposition methods, apparatus, and systems can be also used to provide structures not easily provided using conventional techniques. For example, solid state deposition techniques can be used to provide a multi-layered housing. The multi-layered housing can be formed using any number of processes that utilize solid state deposition of materials having desired properties. Solid state deposition formed from thermally conductive materials can be used to form a thermal path in the form of a conduit, such as a heat pipe, within an enclosure. Once the conduit is formed the heat pipe can be rendered functional by adding a cooling medium, such as water, that undergoes a suitable phase change within the conduit. Electrically conductive material can be used to form electrically conductive traces on electrically insulating material. For example, copper can be deposited using a suitable solid state deposition process on an electrically insulating layer, such as aluminum oxide. In some cases, metals such as titanium can also be used. In some cases, metals such as titanium can undergo a more rigorous deposition process in that the titanium metal can be embedded within the aluminum oxide and not just as a layered deposition on the surface of the aluminum oxide. In this way, solid state deposition of materials formed on an electrically insulating layer (such as aluminum oxide) can be used to form electrical traces or conductive paths. Such electrical traces or conductive paths can be used as antenna or be used as grounding paths. Also, in some cases, electrically conductive layers can be embedded within a housing. 
     In some cases, a removable body can be embedded within a housing by overlaying material using a suitable solid state deposition process. For example, the removable body can be formed into complex shapes using low melt material such as plastic that can then be embedded within an enclosure using a solid state deposition process. In this way, complex internal shapes having features (such as undercuts) that can be difficult to create can nonetheless be formed within an enclosure without resorting to complex machining operations. It should be noted that once the complex-shaped body is in place, a solid state deposition process can then be used to overlay the complex-shaped body with a suitable material having a melting point higher than that of the complex-shaped body. In some cases, the solid state overlay can be machined to a desired external shape and heated to a temperature greater than the melting point of the complex-shaped body embedded therein. In this way, the body can be removed by melting or undergoing some other change of state or phase. In some cases, the complex-shaped body can include portions that can be used to form reinforcing structures such as ribs, trusses, and so on. 
     In some cases, cavities can be formed within the walls of an enclosure. The cavities can be formed using the removable body approach discussed above. The cavities can be used in many ways. For example, the cavities can be used to reduce an overall weight of the enclosure without seriously affecting the overall strength. For example, the cavities can take on stress distributing shapes (such as a honeycomb or ribs) that can be used to evenly distribute loads applied to the housing. In some cases, the cavities can be used as acoustic volumes for enhancing audio performance of a speaker or other type audio transducer. 
     The removable body can also include components embedded within that can remain behind after the material that forms the body has been removed. The components can be passive or active electrical components (for example, speaker boxes or transducers) that can withstand the effects of the solid state deposition process and any subsequent removal process requiring elevated temperatures. In this way, components can be embedded within walls of an enclosure without resorting to complex and difficult-to-perform machining operations. The components can also include structural elements. 
     A multi-layer housing formed of materials layered according to a desired property or properties can be provided. The layers can be formed of material that is either or both electrically and thermally conductive, and in addition provide reinforcement structures. For example, electrically conductive layers formed of suitable conductive material (such as copper) can be used to form an electrically conductive layer within the walls of an enclosure. The conductive layers can be electrically isolated from surrounding enclosure material (such as aluminum or steel) that would cause electric charge leakage. Accordingly, layered structures within the walls of the enclosure can include electrically conductive layers separated by non-conductive layers that isolate the electrically conductive layers from each other. 
     In some cases, thermal paths within the walls on an enclosure can be formed. The thermal paths can be formed of thermally conductive material (that may or may not also be electrically conductive). The thermally conductive paths can be used to transport heat from a heat source (such as an operational component) and a heat sink (such as a fin stack). 
     In some embodiments, cavities can be formed within the wall of an enclosure and replaced with material having a lesser density than that of the material that forms the enclosure. In this way, the overall weight of the enclosure can be reduced. In some cases, the material can also provide improved strength and resistance to impact. Such materials can include, for example, carbon fibers, and so forth. As noted above, the lighter weight materials can be incorporated into a sacrificial body (discussed above) that can be embedded within the walls of the enclosure and then removed by any suitable mechanism (such as melting a low melt temperature material). In this way, the thermally conductive paths act as a heat pipe or other heat transport mechanism. 
     In some embodiments, local features formed of material that is dissimilar to that of the base substrate of the enclosure can be attached in accordance with a solid state deposition process. For example, a nut or (threaded) boss can be attached to an enclosure. In this way, the nut or boss can be used to support a fastener in tension that is nonetheless well adapted to resist compressive forces due to the solid state deposition used to attach the nut or boss. In one situation, a local feature can be formed on an extruded substrate without resorting to machining operations that can be costly in time, material, and expense. For example, a local feature such as a nut or boss (formed of stainless steel, as an example) can be attached to a substrate formed of a dissimilar material (such as aluminum) that would not otherwise be suitable for conventional securing operations such as welding (laser welding, as an example). 
     Solid state deposition processes to cosmetically enhance the appearance of a joint, to form structural elements within and on substrates, and other applications of solid state deposition processes are also discussed hereinafter. Solid state deposition processes function by propelling particles at high velocity to impact a substrate. When the particles impact the substrate, the particles undergo plastic deformation, forming a metallurgical bond to the surface. The most common method of solid state deposition is known as “cold spray.” Cold spray is used traditionally in repair processes, such as in repair of military equipment. Various other embodiments of solid state deposition, which may also be referred to as thermal spraying include, for example, plasma spraying, detonation spraying, wire arc spraying, flame spraying, high velocity oxy-fuel (HVOF) coating spraying, and warm spraying. 
     Because solid state deposition is a solid state process, it has many advantages as such as reduced heat input, oxidation, and grain growth. Further advantages of solid state deposition, and in particular cold spray are as follows: high deposition rate, no or little masking required, no grit blast required, high density, flexibility in substrate coating, minimum thermal input to substrate, high bond strength, compressive residual stresses, ultra-thick coatings (optional), no oxidation, no grain growth, high conductivity, high corrosion resistance, and high strength and hardness. 
     A simplified diagram of the cold spray process is shown in  FIG. 1 . As illustrated, the cold spray process may include directing powder particles  102  and a carrier gas  104 , which may be heated, through a nozzle  106 . The resulting high-velocity particle-gas mixture  108  may thus be directed at a substrate  110 . As the high-velocity particle-gas mixture  108  impacts the substrate  110 , a layer of deposited material  112  may form thereon as the particles plastically deform and bond to substrate  110 . The thickness of the resulting layer of deposited material  112  continues to build to the extent desired as additional particles are directed thereto. Due to the high velocity emission (and resultant high kinetic energy) of the particles form the nozzle  106 , the particles may join together with other particles upon impact. However, unlike other liquid-based depositions, the solid state deposition process defined by a cold spray still allows for the particles to be identifiable. That is, discrete, non-continuous particles joined together may still be individually identified. 
     One advantage of solid state deposition processes such as cold spray is that the material from which the powder particles are formed may be selected to define a desirable characteristic. Accordingly, for example, the material defining the powder particles may be selected to match the material defining the substrate. In some embodiments, the substrate defines a computer housing formed from aluminum (e.g., A1-6063-T6), and the powdered particles are formed from the same aluminum (e.g., AA6063-325 mesh/+10 microns or AA6063-325 mesh/+5 microns). However, as discussed below, differing materials may be selected in other embodiments. 
     The basic requirement for powder particles  102  is that they must be able to flow through the nozzle. Cold spray is done almost exclusively with atomized powder. The atomization process generates spherical particulates which flow well through the nozzle. For cold spray, the powder particles need to be approximately in the range of 5-50 μm diameter to be effective. Uniformity of the size of the powder particles is advantageous in that deposition rates increase with less variation in size. 
     With respect to carrier gas  104 , typically helium and nitrogen are employed for cold spraying. Both gases are considered inert during cold spray. Helium is required to cold spray some high melting temperature alloys. This is because velocities achieved with nitrogen are insufficient to provide the kinetic energy required for the particle to bond with the substrate on impact. In this regard, the sonic velocity of helium is three times that of nitrogen. Further, attempting to soften some high melting temperature alloy powders to enable cold spray using nitrogen may not be feasible because it would require the nitrogen to be heated to a temperature at which the gas is no longer inert. However, helium gas may be considerably more expensive than nitrogen unless helium recycling systems are used. Accordingly, helium gas may be used only when high sonic velocities or pre-heat temperatures are required for the particular cold spray application. The solid state deposition (e.g., cold spray) process may be used in any of the embodiments below to form structures having various desired properties. 
     Solid state deposition may also be employed for other purposes. In this regard, solid state deposition may be employed in joining two or more parts, as illustrated in  FIGS. 2A and 2B .  FIG. 2A  shows first part  202  and second part  204  in contact at a planar interface  206 . In some embodiments, the solid state deposition can itself be operable to join the parts  202 ,  204  together. More particularly, the parts  202 ,  204  can be joined together at the planar interface  206  by applying solid state deposition to respective outer surfaces  208 ,  210  of the parts  202 ,  204  proximate the interface, as depicted in  FIG. 2B . Accordingly, the solid state deposition can extend across both sides of the planar interface  206  to join the parts  202 ,  204  together. 
       FIG. 3  shows an embodiment in which cold spray is used to secure one side of housing  300 . Plate  302  can slide within first groove  306  and second groove  307  of housing component  304 . First groove  306  and second groove  307  can position plate  302  within housing component  304  so that plate  302  is disposed along a top surface of housing component  304 . An interface  308  between plate  302  and housing component  304  can define a small gap that can be configured to receive cold spray material. By applying cold spray material within the gap defined by interface  308 , plate  302  can be permanently affixed to housing component  304 . 
     The particular parts joined by solid state deposition may vary. However, by way of example,  FIGS. 4A-4E  illustrate steps that can be taken to join a boss to a substrate via solid state deposition.  FIG. 4A  shows an exemplary substrate  402 . In one particular embodiment, substrate  402  can be a relatively soft metal such as aluminum forming a portion of a device housing.  FIG. 4B  shows opening  404  machined through substrate  402 . Opening  404  can have any of a number of geometries. For example, opening  404  can be circular or rectangular.  FIG. 4C  shows how subsequent to formation of opening  404 , an insert can be placed within opening  404 . In some embodiments, insert  406  can be a boss configured to receive a fastener. Regardless, at least a base portion of insert  406  has a size and shape such that it fits within opening  404 . In some embodiments, a geometry of insert  406  that interacts with walls defining opening  404  can prevent insert  406  from rotating when disposed within opening  404 . In  FIG. 4D  solid state deposition layer  408  is added along a top surface of substrate  402 . In this way, insert  406  becomes secured within opening  404 . An opening in insert  406  can be covered up by, for example a plug, to prevent entry of solid state deposition within opening  410  of insert  406 . In a final step,  FIG. 4E  shows how a portion of solid state deposition layer  408  can be machined away to create a cosmetic surface proximate insert  406 . Such an arrangement allows addition of a boss or attachment feature anywhere along a surface of a metal substrate. Solid-state deposition layer  408  can be configured to match substrate  402 , allowing a cosmetic surface of substrate  402  to be maintained when desired. Another advantage of this configuration is that a robust coupling can be formed between substrate  402  and boss  406  even when the materials of the two components are highly dissimilar. For example, a boss  406  made from steel would not laser weld to substrate  402  when substrate  402  is aluminum. Furthermore, this method also has advantages over a press fit insert as a press-fit insert is subjected to some level of deformation which can affect tolerances of the insert. It should also be noted that while opening  404  is depicted extending completely through substrate  402 , alternatively a pocket that does not extend through the substrate can also be utilized using a similar procedure. 
     In some embodiments, a part can be formed by an additive manufacturing process making a feature entirely from cold spray material. In this regard,  FIG. 5A  illustrates a solid state deposition  502  formed on substrate  504 . As illustrated in  FIG. 5B , a portion of the solid state deposition  502  may be machined away to form an exterior geometry of the part. This may be a predetermined geometry based on a desired geometry. By forming the part in this manner, issues with respect to a heat affected zone causing cosmetic defects may be entirely avoided since no welding is required to join the part to substrate  504 .  FIG. 5C  shows how threaded aperture  506  can be machined out to complete formation of boss  508 . It should be noted that this technique is not limited to formation of bosses and can include formation of other protruding parts such as for example structural ribs or alignment features. 
     Note that although the solid state deposition is generally discussed herein as comprising a single type of material, in other embodiments multiple materials may be employed. For example,  FIG. 6A  illustrates first part  602  and second part  604  with a groove  606  therebetween.  FIG. 6B  shows how groove  606  is filled by first solid state deposition  608 A that includes a first material.  FIG. 6C  shows how second solid state deposition  608 B that includes a second material that differs from the first material can be deposited subsequent to deposition of first solid state deposition  608 A. Thus, second solid state deposition  608 B can define a material and configuration configured to match the surrounding material of the parts  602 ,  604  for cosmetic purposes. However, first solid state deposition  608 A, which may be entirely hidden from view, may be selected to define other desirable characteristics. Thus, for example, first solid state deposition  608 A may include titanium or other material configured to provide the assembly with high strength and light weight, whereas second solid state deposition  608 B may comprise aluminum in order to match the surrounding first part  602  and second part  604 . Note that titanium is generally not work-hardenable, and hence solid state deposition does not cause it to become brittle. However, various other materials may be employed in other embodiments. 
     Solid state deposition may also be employed to form internal voids having specific geometries. In this regard,  FIG. 7A  illustrates a cross-sectional view of solid state deposition  702  deposited on removable body  704  (also referred to as a sacrificial body) positioned on substrate  706 . After solid state deposition  702  is formed, a portion of the solid state deposition  702  can be removed by a machining operation. The machining operation can cause an exterior geometry of solid state deposition  702  to have a geometry along the lines of the geometry shown in  FIG. 7B . During the machining operation, removable body  704  can provide support to solid state deposition  702 , thereby preventing deformation of removable body  704 .  FIG. 7C  shows removable body  704  removed. For example, removable body  704  can be removed by dissolving or melting means. In this regard, removable body  704  may be formed from materials such as foam, wood, honeycomb, etc. After removal of removable body  704 , void  708  may be defined in the space previously filled by removable body  704  as depicted in  FIG. 7C , providing the resulting assembly with a lightweight construction. In some embodiments, components can be subsequently added within void  708 . Void  708  has the benefit of being defined by sidewalls without any substantial machining defects such as burrs or scratches. This can be highly beneficial when mounting a component within void  708  that is susceptible to damage from scratching or puncture. 
       FIGS. 8A-8B  show another hollow structure that can be formed by solid state deposition. In  FIG. 8A  cold spray  802  is deposited over substrate  804  and removable body  806 . Subsequent to deposition of cold spray  802 , removable body  806  can be removed by melting or in some cases dissolving to leave void  808 , as depicted in  FIG. 8B . An exterior portion of cold spray  802  can be machined away, which is also depicted in  FIG. 8B . This configuration can provide a number of unique advantages. For example, cold spray  802  can be operable as a structural rib. When a structural rib is subject to a bending moment, stress is typically concentrated along a periphery of the rib. For this reason, void  808  may not provide a reduction in strength associated with the structural rib, and substantial weight savings can be realized. Void  808  can also be utilized to conduct audio signals. Because cold spray  802  can effectively seal itself to substrate  804 , leakage of audio out of void  808  can be extremely minimal. In some configurations, void  808  can form a channel through which cooling air can flow. 
       FIGS. 9A-9D  illustrate formation of an assembly with an embedded item within a solid state deposition, in accordance with the described embodiments of the present disclosure. As illustrated in  FIG. 9A , first solid state deposition  902  can be deposited on substrate  904 .  FIG. 9B  illustrates how pocket  906  can be machined in first solid state deposition  902 .  FIG. 9C  illustrates how item  908 , such as a thermally or electrically conductive item (e.g., copper, graphite, carbon fiber, a heat pipe, etc.) may be placed in pocket  906 . In some embodiments, operational components, such as antennas can be embedded in this way. Thereafter, second solid state deposition  910  can be employed to enclose item  908  in pocket  906 . Second solid state deposition  910  can be formed from the same material as first solid state deposition  902 , or in other embodiments, can be formed of a different material. 
       FIGS. 10A-10D  illustrate formation of a multi-layer assembly. Each layer of the multi-layer assembly can impart different beneficial characteristics to the assembly.  FIG. 10A  shows substrate  1002 . Substrate  1002  can be a small portion of a larger structure, such as a device housing.  FIG. 10B  shows first cold spray layer  1004  applied to a bottom surface of substrate  1002 . In some embodiments, first cold spray layer  1004  can follow an entire exterior surface of a housing associated with substrate  1002 . Such a configuration may be desirable when first cold spray layer  1004  is optimized for conduction of thermal energy. Subsequent to application of first cold spray layer  1004 , second cold spray layer  1006  can be selectively applied to first cold spray layer  1004 . Selective application of second cold spray layer  1006  can be appropriate when second cold spray layer  1006  includes high cost and/or heavy materials. For example, second cold spray layer  1006  can include titanium for providing stiffness to substrate  1002 . Application of second cold spray layer  1006  can then be limited to portions of substrate  1002  that need additional reinforcement or additional stiffness. Also, in some cases, it may be desirable to remove a portion of second cold spray layer  1006 .  FIG. 10C  shows the embodiment shown in  FIG. 10B , with gap  1007  formed within second cold spray layer  1006 . This allows for a subsequent layer to be formed on both first cold spray layer  1004  and second cold spray layer  1006 . For example,  FIG. 10D  shows application of third cold spray layer  1008  formed on first cold spray layer  1004  and second cold spray layer  1006 . Third cold spray layer  1008  can be configured to fill in gaps e.g., gap  1007  shown in  FIG. 10C ) where second cold spray layer  1006  was not applied. Furthermore, it can also cover second cold spray layer  1006  so that an exterior surface of the multi-layer assembly is substantially uniform in appearance. In some embodiments, second cold spray layer  1006  can have material properties that facilitate application of a highly polished cosmetic surface, and/or can be configured to receive an anodization layer. 
       FIGS. 11A-11E  illustrate a number of steps for securing a hinge or clutch element to a housing  1102  of an electronic device.  FIG. 11A  shows a side view of a portion of housing  1102  for a portable computing device. The housing includes sidewall  1104  and bottom wall  1106 .  FIG. 11B  shows clutch component  1108  being pressed against sidewall  1104  of housing  1102  with a Force F to press clutch component  1108  against sidewall  1104  and bottom wall  1106 . Clutch component  1108  can have a geometry complementary to a geometry of sidewall  1104  and an adjacent portion of bottom wall  1106 . Clutch component  1108  can also have an opening  1110  for receiving a shaft portion of an associated clutch assembly component.  FIG. 11C  shows clutch component  1108  subsequent to receiving a layer of cold spray  1112 . Once cold spray  1112  is applied, clutch component  1108  becomes effectively secured to housing  1102 . In some embodiments, clutch component  1108  can be formed of steel and cold spray  1112  can also be formed of steel thereby creating a robust coupling between clutch component  1108  and housing  1102 . A moment can be applied to clutch component  1108  that is typical of a moment transmitted from the shaft to clutch component  1108  during normal operation of the clutch component. As depicted, sidewall  1104 , bottom wall  1106  and cold spray  1112  can all cooperate to prevent clutch component  1108  from becoming disengaged from housing  1102  as a result of the moment.  FIG. 11D  shows a perspective view of clutch component  1108  covered by cold spray  1112 . It should be noted that opening  1110  can receive a portion of cold spray  1112  if not covered during a deposition operation. In cases where opening  1110  is not covered during deposition, cold spray  1112  can be machined out of opening  1110 . In other embodiments, opening  1110  can be formed after deposition of cold spray  1112 . In this way, clutch component  1108  can be securely adhered to housing  1102  without need for screws or adhesive. 
       FIGS. 12A-12D  show various embodiments in which a cold spray operation can be applied to form a reinforcement feature.  FIG. 12A  shows a partial top view of an interior of a housing  1200  of an electronic device. In some embodiments, housing  1200  is formed from aluminum. When exterior walls of housing  1200  are particularly thin, curved corner portions of housing  1200  can be particularly susceptible to damage. In some embodiments, a corner portion of housing  1200  can be reinforced by applying cold spray to form stiffener  1202 . In one embodiment, stiffener  1202  is formed from steel particles. By cold spraying stiffener  1202  to housing  1200 , use of adhesives can be avoided, reducing a volume (or stack) taken up by the adhesive, and allowing a robust connection between the stiffener  1202  and housing  1200  to be formed.  FIG. 12B  shows a partial cross-sectional side view in accordance with section line A-A in  FIG. 12A . This cross-section makes it clear how stiffener  1202  can adhere to a thin, curved surface of housing  1200 , thereby reinforcing the curved geometry to substantially reduce a likelihood of damage to the corner during a drop event. Furthermore, because an extra layer of adhesive is not required, more room is left within housing  1200  for additional components.  FIG. 12C  shows a partial top view of an interior of a housing  1250  of an electronic device. A corner bracket  1252  formed from a solid state deposition is formed along a corner of housing  1250 . Corner bracket  1252  can help to prevent damage to the corner in the event of a drop event.  FIG. 12D  shows a partial cross-sectional side view of corner bracket  1252  in accordance with line B-B shown in  FIG. 12C .  FIG. 12D  shows how corner bracket  1252  can be in direct contact with a sidewall of housing  1250 . In this way, a corner portion of housing  1250  can be substantially reinforced. This can be especially effective when the material forming corner bracket  1252  is formed of a stronger or more rigid material than the material used to form housing  1250 . For example, housing  1250  can be formed of aluminum while corner bracket  1252  can be formed of stainless steel. 
       FIGS. 13A-13I  show cross-sectional views of housing  1302  and various methods for applying a solid state deposition (e.g., cold spray) to form a reinforced opening for an I/O port. The I/O port may be configured to receive, for example, a jack for headphones or a connector of a power cord.  FIG. 13A  shows housing  1302  and opening  1304  machined from housing  1302 . Opening  1304  includes a shoulder region for defining the reinforced I/O port opening. In  FIG. 13B , plug  1306  is inserted within opening  1304 . Plug  1306  cooperates with the shoulder regions of opening  1304  to define a channel for receiving cold spray material.  FIG. 13C  shows cold spray material deposited within the channel. Finally, in  FIG. 13D , plug  1306  is removed and the cold spray material is machined to match a surrounding portion of housing  1302 , thereby forming reinforced band  1310 . In this way, reinforced band  1310  can protect a peripheral portion of the I/O port.  FIG. 13E  shows a partial perspective view of a portion of electronic device  1320  with reinforced band  1310 . Reinforced band  1310  can be formed of polished steel which provides both a cosmetically appealing appearance and structural reinforcement for the I/O port. 
     Alternatively, plug  1306  can be omitted from this described process.  FIG. 13F  shows opening  1304  machined into housing  1302 . Opening  1304  is then filled with cold spray  1308  as depicted in  FIG. 13G . Opening  1304  is then reformed (by a material removal process) and can pass entirely through housing  1302 , as depicted in  FIG. 13H , providing access to a connector circuit disposed within the housing  1302 . Finally, in  FIG. 13I , a top portion of cold spray  1308  is machined away leaving reinforced band  1312  of cold spray material disposed around opening  1304 . In some embodiments, reinforced band  1312  is formed of polished stainless steel. 
       FIG. 14A  shows a cross-sectional side view of a housing  1400 , showing removable body  1402  disposed in a corner region of housing  1400  with cold spray applied to a top surface of the removable body  1402  to form wall  1404 .  FIG. 14B  shows how removable body  1402  can be removed, leaving wall  1404  to create void  1406  having a substantial undercut geometry within which various components can be positioned.  FIG. 14C  shows housing  1410  with a removable body  1412  disposed within a corner region of the housing  1410 . Removable body  1412  includes a number of complex features along its top surface for forming features with cold spray material. For instance, removable body  1412 , as shown in  FIG. 14C , includes a rib structure.  FIG. 14D  illustrates a structured formed on removable body  1412  by a solid state deposition process (e.g., cold spray). As shown, removable body  1412  includes a solid state deposition layer defined by wall  1414  formed against the complex features of removable body  1412 .  FIG. 14E  shows how in some embodiments, removable body  1412  can include an embedded component  1416 . While embedded component  1416  is shown completely embedded in removable body  1412 , in some embodiments, embedded component  1416  protrudes freely from removable body  1412  so that at least a portion of embedded component  1416  can define a geometry of a part cold sprayed against it. Also depicted in  FIG. 14E  is wall  1418  which can be deposited against both removable body  1412  and wall  1414 . Wall  1418  may be formed by similar means as that of wall  1414 . In this way removable body  1412  can be completely enclosed by walls  1414  and  1418 . Finally in  FIG. 14F , removable body  1412  is removed, leaving behind embedded component  1416 . When removable body  1412  is removed, resulting ribs  1420  remain disposed along an interior surface of wall  1414 . Embedded component  1416  is unaffected by the removal of body  1412  and remains intact between walls  1414 ,  1418 . When embedded component  1416  is an electrical component that emits electromagnetic interference (EMI), walls  1414  and  1418  which are seamlessly formed with each other cooperate to form an EMI can thereby preventing leakage of EMI radiated by embedded component  1416 . In other words, walls  1414 ,  1418  combine to define a shield that prevents EMI from penetrating through walls  1414 ,  1418 . Further, walls  1414 ,  1418  prevent EMI penetration thereby preventing EMI from reaching embedded component  1416 . 
       FIG. 14G  shows how cold spray can be used to form a truss structure  1430 . Voids  1432  in truss structure  1430  can be formed by a number of temporary inserts about which cold spray materials can be deposited. In this way, a high strength, low weight structural component can be formed without requiring complex machining operations. 
       FIGS. 15A-15E  show a number of steps for forming a hollow component configured to enhance audio performance of an electronic device.  FIG. 15A  shows removable body  1502  disposed on substrate  1504  and covered by cold spray  1506 . Removable body  1502  may also be a sacrificial body, in accordance with the described embodiments. In  FIG. 15B , an outside surface of cold spray  1506  is machined away. In  FIG. 15C , removable body  1502  is removed leaving a void  1510  and an opening  1508  is machined through cold spray  1506 . Also, the area enclosed by the housing and structure formed by cold spray  1506  define an acoustic volume. In  FIG. 15D , audio component  1512 , such as an audio driver, is inserted within opening  1508 . Finally, in  FIG. 15E , audio component  1512  is affixed and sealed within opening  1508  by a layer of adhesive  1514  disposed about the periphery of audio component  1512 . In this way, void  1510  can form a front volume for audio component  1512 .  FIG. 15F  shows a top view of audio component  1512  disposed within a corner portion of housing  1516  of an electronic device. Here, it can be seen that void  1510  can include an irregular geometry. In this way, a size of the front volume created by void  1510  can be maximized by taking up only space available within housing  1516 . 
       FIG. 16  shows a cross-section of a housing  1600  and a device foot  1602  formed by a cold spray operation into an aperture of housing  1600 . The aperture can have an undercut geometry or can have other geometries facilitating retainer of device foot  1602 . Device foot  1602  can be subsequently shaped by a precision machining operation to have precise height with respect to an outside surface of housing  1600 . 
       FIG. 17  shows a flowchart  1700  representing a method for forming a hollow structure using a solid state deposition process. In step  1702 , a sacrificial body is positioned on a metal substrate. In some embodiments, the sacrificial body can be adhered to the metal substrate to keep it in a precise position during the solid state deposition process. In step  1704 , a layer of metal is deposited over the sacrificial body. The layer of metal can include a mixture of metal particles that have a desirable material property or properties. In some embodiments, the mixture is designed to blend with the metal substrate upon which it is deposited. In step  1706 , a portion of an outside surface of the metal layer is machined away to achieve a predetermined geometry, or in some cases, to generate particular features along the outside surface. For example, a structural rib or attachment feature could be formed during such a machining process. In step  1708 , the sacrificial body is melted or dissolved away, thereby allowing a cavity to be formed within the metal layer having a size and shape in accordance with the sacrificial body. 
     In the embodiments discussed above, solid state deposition is indicated as working with dissimilar materials on a substrate to which the solid state deposition is applied. In various other embodiments, the processes described above may be modified. For example, in some embodiments, particles defining differing particle sizes are deposited at the same time to provide the resulting solid state deposition with a more complex surface texture. Further, solid state deposition may be employed to create electrostatic discharge (ESD) shielding, electromagnetic pulse (EMP) shielding, and/or radio frequency (RF) leakage shielding, without damaging the shielded components. Additionally, the solid state deposition may be deposited to define complex structures such as in the form of trusses that provided a lightweight, yet strong, structure, rather than in uniform layers. 
     In some cases, it may be necessary to strengthen a channel formed within a substrate.  FIGS. 18-20  illustrate a process for using a solid state deposition process in a manner previously described to strengthen a channel.  FIG. 18  illustrates a side view of substrate  1800  having channel  1802  formed within substrate  1800 , in accordance with the described embodiments. Channel  1802  includes first layer  1804  formed by a solid state deposition process at a relatively high temperature and pressure. As a result, the density of first layer  1804  is relatively high as the particles are highly condensed, and in some cases, melted. First layer  1804  may be particles of metal such as aluminum, titanium, magnesium, or any other materials previously described for solid state deposition. 
       FIG. 19  illustrates the embodiment of substrate  1800  shown in  FIG. 18 , with second layer  1806  applied to first layer  1804 . Second layer  1806  may also be formed from a solid state deposition process. However, the solid state deposition process used to form second layer  1806  uses a relatively low temperature and pressure, as compared to the temperature and pressure used to form first layer  1804 . As a result, second layer  1806  is a relatively porous, i.e., less dense, layer as compared to first layer  1804 . 
       FIG. 20  illustrates the embodiment of substrate  1800  shown in  FIG. 19 , with third layer  1808  applied to second layer  1806 . Third layer  1808  may also be formed from a solid state deposition process. However, the solid state deposition process used to form third layer  1808  uses a relatively high temperature and pressure, as compared to the temperature and pressure used to form second layer  1806 . For instance, third layer  1808  may be formed with a density substantially similar to that of first layer  1804 . As a result, a solid state deposition process may include first layer  1804  and third layer  1808  forming relatively dense regions, with second layer  1806  positioned between first layer  1804  and third layer  1808 . In order to ensure sufficient bonding, the layers described in  FIG. 20  may be fused together. For example, second layer  1806  may fuse with both first layer  1804  and third layer  1808 . This ensures the layers are intact. 
       FIGS. 21-24  illustrate a technique for compensating for solid state deposition issues related to bonding together materials having different properties, such as different coefficients of thermal expansion.  FIG. 21  illustrates an isometric view of substrate  1900  having channel  1902  formed within substrate  1900 , in accordance with the described embodiments. In some embodiments, substrate  1900  is formed from aluminum. Also, in some embodiments, substrate  1900  is used as a stiffening member used in applications, for example, to provide support to a display housing of an electronic device. 
       FIG. 22  illustrates a cross sectional view of the embodiment of substrate  1900  shown in  FIG. 21  taken along the  22 - 22  line, with channel  1902  filled with first layer  1904  and second layer  1906 . First layer  1904  can be formed form a solid state process previously described. First layer  1904  may include materials such as steel (e.g., stainless steel), stellite (chromium-cobalt), or a combination thereof. Generally, first layer  1904  is made from materials that erode when exposed to an anodization process that includes the use of one or more abrasive chemicals, such as phosphoric acid, sulfuric acid, and/or oxalic acid. As a result, first layer  1904  should be covered with another layer, such as second layer  1906 . In some embodiments, second layer  1906  is formed from a solid state deposition process. Also, in some embodiments, second layer  1906  is formed from titanium particles. Generally, second layer  1906  may be formed from any material or materials capable of withstanding exposure to an anodization process. Also, second layer  1906  may be applied using relatively high heat (e.g., approximately 950 degrees Celsius) and relatively high pressures (e.g., 5 MPa). 
     While, second layer  1906  is suitable for withstanding harsh environments, the application process can create certain issues. For example,  FIG. 23  illustrates the cross sectional view of the embodiment of substrate  1900  shown in  FIG. 22  shortly after second layer  1906  is applied over first layer  1904 . As shown, substrate  1900  is warped or bowed, particularly in a central region. This can be attributed in part to differences between substrate  1900  and second layer  1906 . For example, substrate  1900  may include a temperature much lower than that of second layer  1906 . For example, prior to applying second layer  1906 , substrate  1900  may be at room temperature. However, at least some of the relatively high temperature of second layer  1906  is dissipated into substrate  1900  upon impact. Also, substrate  1900  may include a coefficient of thermal expansion much lower than that of second layer  1906 . As a result, the increased temperatures cause substrate  1900  to change volume (or shape). In some cases, substrate  1900  may bow such that substrate  1900  includes a distance  1910  approximately in the range of 2 to 5 millimeters, where distance  1910  is measured from substrate  1900  to an imaginary horizontal plane. As a result, substrate  1900  may no longer be used in the intended applications. 
     The bonding of subsequent layers of solid state deposition may be improved based on the channel geometry of a substrate. For instance, a channel having relatively sharp edges, that is, edges formed from a vertical wall intersecting with a horizontal wall, may be less suited to receive solid state deposition. In this regard,  FIGS. 24-26  illustrate substrates having channels with various geometries.  FIG. 24  illustrates a side view of an embodiment of substrate  2000  having channel  2002  having first sidewall  2004  and second sidewall  2006  formed at angle  2008 . As shown, first sidewall  2004  forms angle  2008  with respect to an imaginary vertical line. Angle  2008  may be approximately 10 degrees. Second sidewall  2006  may form an angle similar to that of angle  2008 . 
       FIG. 25  illustrates a side view of an alternate embodiment of substrate  2100  having channel  2102  having first sidewall  2104  and second sidewall  2106  formed at angle  2108  greater than angle  2008  shown in  FIG. 24 . As shown, first sidewall  2104  forms angle  2108  with respect to an imaginary vertical line. Angle  2108  may be approximately 25 degrees. Second sidewall  2106  may form an angle similar to that of angle  2108 . 
       FIG. 26  illustrates a side view of an alternate embodiment of substrate  2200  having channel  2202  having first sidewall  2204  and second sidewall  2206  formed at an angle  2208  greater than angle  2208  shown in  FIG. 25 . As shown, first sidewall  2104  forms angle  2208  with respect to an imaginary vertical line. Angle  2208  may be approximately in the range of 40 to 50 degrees. In particular, in some embodiments, angle  2208  is approximately 45 degrees. Second sidewall  2206  may form an angle similar to that of angle  2208 . 
     Also, as shown in  FIG. 26 , substrate  2200  includes first layer  2214  and second layer  2216 , both of which may be applied to substrate  2200  by separate solid state deposition processes. Traditional solid state deposition processes in which a channel having substantially horizontal and vertical surfaces may not allow second layer  2216  to bond with first layer  2214  in a desired manner. For example, small micro-cracks formed with first layer  2214  may not be fully filled with second layer  2216 , particularly in substantially vertical cracks. However, as shown in the enlarged view of  FIG. 26 , first layer  2214  includes cracked region  2220  having several micro-cracks which are substantially, if not completely, filled with a portion of second layer  2216 . In this manner, second layer  2216  is more tightly secured to first layer  2214 . The increased angular configuration leads to less of a “transition region” defined by an edge region where two surfaces meat. The lesser transition region in turn allows for better particle deposition of a solid state deposition. 
       FIGS. 27-29  illustrate a first layer formed on a substrate, further with a second layer formed over the first layer. Both the first layer and the second layer may be applied to the substrate by a solid state deposition process. While the first layer may be applied to the substrate with relative ease, the materials forming the second layer may not bond with the first layer in a desired manner. 
       FIG. 27  illustrates an embodiment of substrate  2300  undergoing a solid state deposition process to form first layer  2304  on substrate  2300 . In some embodiments, substrate  2300  is formed from aluminum. Also, in some embodiments, first layer  2304  is formed from a relatively dense material or materials as compared to substrate  2300 , such as titanium particles. Also, first layer  2304  may include a relatively high melting point. As a result, first layer  2304  may deform or penetrate a portion of substrate  2300  upon impact, as shown in  FIG. 27 .  FIG. 28  illustrates the embodiment of substrate  2300  shown in  FIG. 27 , with the solid state deposition process forming first layer  2304  having a relatively flat or level surface. 
       FIG. 29  illustrates the embodiment of substrate  2300  shown in  FIG. 28 , with substrate  2300  undergoing a second solid state deposition process to form second layer  2306  over a portion of first layer  2304 . In some embodiments, second layer  2306  is formed from aluminum particles. In some cases, second layer  2306  includes a lower density than that of first layer  2304 . Further, second layer  2306  may include a relatively lower melting point as compared to first layer  2304 . As a result, second layer  2306  may not sufficiently bond with first layer  2304 . For example, as shown in  FIG. 29 , some particles configured to form second layer  2306  carom off of first layer  2304 . Alternatively, some particles configured to form second layer  2306  simply contact first layer  2304 , as opposed to penetrating first layer  2304  in a manner similar to first layer  2304  penetrating substrate  2300  (as shown in  FIG. 27 ). This is due in part to second layer  2306 , having a relatively low melting point, being heated substantially during the solid state deposition process. This causes second layer  2306  to become at least partially melted, and accordingly, soft. Also, first layer  2304  may absorb heat from second layer  2306  upon impact, further reducing the bonding strength. 
     However, some techniques may be used to form a stronger bond between first layer  2304  and second layer  2306 . For example,  FIG. 30  illustrates the embodiment of substrate  2300  shown in  FIG. 28 , with first layer  2304  having a rough or unsmooth surface. This may be accomplished by a material removal process such as blasting (e.g., sand blasting, grit blasting) first layer  2304 .  FIG. 31  illustrates the embodiment of substrate  2300  shown in  FIG. 30 , with second layer  2306  applied over first layer  2304 . Second layer  2306  is able to bond with first layer  2304  due in part to the rough surface of first layer  2304 . The rough surface allows second layer  2306  to better conform and mechanically lock with first layer  2304 . 
     A method for forming a void within a structure may be performed by a solid state deposition process, in accordance with the described embodiments. The method includes spraying several discrete metallic particles on at least a portion of a sacrificial body that includes a size and a shape. The several discrete metallic particles can congeal or join subsequent to the spraying to form a corresponding metallic layer. The term “congeal” as used throughout this detailed description and in the claims refers to a solidification of particles when the particles have been deposited (e.g., by a cold spraying process). The method further includes creating the void within the layer having the size and shape of the sacrificial body by removing the sacrificial body in a manner that an external surface of the layer remains essentially undisturbed. The method further includes forming the structure by physically altering an external portion of the layer. In some embodiments, physically altering the external portion of the layer includes removing an amount of the layer subsequent to the spraying of the several discrete particles but prior to creating the void. Alternatively, in some embodiments, physically altering the external portion includes removing an amount of the layer subsequent to creating the void. 
     The sacrificial body may be removed by means such as dissolving and/or melting the sacrificial body. Also, the sacrificial body includes a melting temperature less than that of the layer of material. In this manner, the sacrificial body may be heated to a temperature above the melting temperature of the sacrificial body but lower than the melting temperature of the layer of materials. In this manner, the sacrificial body is melted but the layer of materials is not melted. Also, in some embodiments, a component is embedded within the sacrificial body. The component can remain in the void after the sacrificial body is removed. 
     In some instances, the sacrificial body includes an indentation having a size and a shape of a rib structure. In some cases, the rib structure is at least partially filled with the several discrete metallic particles during the spraying and wherein upon removal of the sacrificial body, at least some of the several discrete metallic particles congeal or join within the indentation form a corresponding rib structure. In some cases, rib structure provides a reinforcement to the layer of material after the sacrificial body is removed. 
     The sacrificial body can include an indentation having a size and a shape of a rib structure that is at least partially filled with metallic particles during the spraying and wherein upon removal of the sacrificial body, the congealed or joined metallic particles within the indentation form the rib structure 
     A method of electrically isolating an electrical component may be performed by a solid state deposition process, in accordance with the described embodiments. The method includes spraying several discrete metallic particles that include a conductive material over at least a portion of a sacrificial body that carries the electrical component forming a conductive shield that acts as a barrier to passage of electromagnetic energy. The method further includes removing the sacrificial body in a manner that leaves the electrical component substantially unaffected and the conductive shield undisturbed. The conductive shield prevents most, if not substantially all, of the electromagnetic energy emitted by the electrical component from reaching an external environment. Moreover, the conductive shield prevents most, if not substantially all, of the electromagnetic energy from the external environment from reaching the electrical component. 
     In some cases, when the electrical component is capable of sending or receiving radio frequency (RF) energy, an opening is formed in the conductive shield that allows passage of the RF energy. Further, in some cases, only the opening allows passage of the RF energy. Also, in some cases, the opening is covered with a radio transparent material that prevents external contaminants from reaching the RF energy capable electrical component. 
     An electronic device may include a portion formed by a solid state process, in accordance with the described embodiments. The electronic device includes a housing. The electronic device further includes a component assembly carried by the housing. The component assembly includes an enclosure formed of a solid state deposition layer that includes several congealed (or joined) metallic particles that form a corresponding metallic layer that encloses and defines an internal volume. The component assembly may further include a component at least partially disposed within the internal volume. In some cases, the electronic device is capable of producing an audible sound. 
     In some embodiments, the component assembly further includes an audio transducer that provides acoustic energy. The audio transducer can be acoustically coupled to the internal volume to cooperate with the internal volume in a manner that converts the acoustic energy into the audible sound. Further, the enclosure may include an opening having a size and a shape that accommodates the audio transducer. In some cases, the audio transducer is positioned within the opening such that the audio transducer emits the acoustic energy into the internal volume. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of specific embodiments are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the described embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20141219
Publication Date: 20180206
Grant Date: 20180206
Priority Date: 20140303
Inventors: LANCASTER-LAROCQUE SIMON REGIS LOUIS
MILLER ARI P.
DEFOREST LAURA M.
GOLDBERG MICHELLE R.
LEGGETT WILLIAM F.
GARELLI ADAM T.
Assignee: APPLE INC
CPC Classifications: [{"code": "B22F3/24", "inventive": true, "first": true, "tree": "[]"}, {"code": "C23C28/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "B05D1/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/2811", "inventive": true, "first": false, "tree": "[]"}, {"code": "B05D1/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "C23C24/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "C23C28/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/2811", "inventive": true, "first": false, "tree": "[]"}, {"code": "C23C24/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "C23C28/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/2811", "inventive": true, "first": true, "tree": "[]"}, {"code": "B05D1/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "B22F3/24", "inventive": true, "first": true, "tree": "[]"}, {"code": "B05D1/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "C23C24/04", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 54006321