PATENT DOCUMENT

Publication Number: US-10920333-B2
Application Number: US-201715418235-A
Country: US
Kind Code: B2

Title: Process for producing white anodic oxide finish

Abstract:
The embodiments described herein relate to treatments for anodic layers. The methods described can be used to impart a white appearance for an anodized substrate. The anodized substrate can include a metal substrate and a porous anodic layer derived from the metal substrate. The porous anodic layer can include pores defined by pore walls and fissures formed within the pore walls. The fissures can act as a light scattering medium to diffusely reflect visible light. In some embodiments, the method can include forming fissures within the pore walls of the porous anodic layer. In some embodiments, exposing the porous anodic layer to an etching solution can form fissures. The method further includes removing a top portion of the porous anodic layer while retaining a portion of the porous anodic layer.

Claims:
What is claimed is: 
     
       1. A method for forming an anodized substrate having a white appearance, the method comprising:
 forming an anodized coating comprising a mixed metal oxide material formed from and overlaying an aluminum alloy substrate, the anodized coating comprising pore walls and bottom portions that define pores; 
 etching light-reflecting fissures within the pore walls, the light-reflecting fissures having lengths between 5 nanometers and 20 nanometers and non-parallel orientations with respect to an outermost surface of the anodized coating, the light-reflecting fissures diffusely reflecting light incident on the outermost surface to impart the white appearance, a concentration of the light-reflecting fissures increasing towards the outermost surface; and 
 depositing light-reflecting particles on the bottom portions by fragmenting an outer portion of the anodized coating, wherein a remaining portion of the coating defines at least some of the etched light-reflecting fissures. 
 
     
     
       2. The method of  claim 1 , further comprising:
 sealing openings of the pore pores subsequent to forming the light-reflecting fissures. 
 
     
     
       3. The method of  claim 1 , wherein the light-reflecting fissures are formed by exposing the anodized coating to an etching solution. 
     
     
       4. The method of  claim 1 , wherein fragmenting the outer portion of the anodized coating reduces a thickness of the anodized coating by between 3 micrometers and 5 micrometers. 
     
     
       5. The method of  claim 1 , wherein the light-reflecting particles are displaced into the bottom portions by fragmenting the outer portion of the anodized coating. 
     
     
       6. The method of  claim 1 , wherein the anodized coating comprises mixed metal oxide material, and the light-reflecting particles comprise the mixed metal oxide material. 
     
     
       7. A housing of a portable electronic device having a white appearance, the housing comprising:
 an aluminum alloy substrate; 
 an anodic layer that comprises a mixed metal oxide material formed from and overlaying the aluminum alloy substrate, the anodic layer comprising;
 bottom portions and pore walls that define pores, the pore walls further defining light-reflecting fissures having lengths between 5 nanometers and 20 nanometers and non-parallel orientations with respect to an outermost surface of the anodic layer, the light-reflecting fissures diffusely reflecting light incident on the outermost surface to impart the white appearance, a concentration of the light-reflecting fissures increasing towards the outermost surface; and 
 
 light-reflecting particles that comprise the mixed metal oxide material and are carried by the bottom portions. 
 
     
     
       8. The housing of  claim 7 , wherein the light-reflecting fissures are etched into the pore walls. 
     
     
       9. The housing of  claim 7 , wherein the light-reflecting particles are sealed within the pores by a sealant. 
     
     
       10. The housing of  claim 7 , wherein the pore walls define fragmented portions with greater concentrations of the light-reflecting fissures than an innermost region of the anodic layer. 
     
     
       11. The housing of  claim 7 , wherein the light-reflecting particles are formed by fragmenting a portion of the anodic layer. 
     
     
       12. The housing of  claim 7 , wherein outermost regions of the pore walls are thinner than innermost regions of the pore walls. 
     
     
       13. An enclosure for a portable electronic device having a white appearance, the enclosure comprising:
 an aluminum alloy substrate; 
 an anodized layer that overlays the aluminum alloy substrate and includes a mixed metal oxide material formed from the aluminum alloy substrate, the anodized layer comprising pore walls and bottom portions that define pores having diameters between about 100 nm and about 500 nm, the pore walls defining light-reflecting fissures having lengths between 5 nm and 20 nm that are etched into the pore walls, the light-reflecting fissures diffusely reflect light incident on an outermost surface of the anodized layer to impart the white appearance, a concentration of the light-reflecting fissures increasing towards the outermost surface; and 
 light-reflecting particles that comprise the mixed metal oxide material and are carried by the bottom portions. 
 
     
     
       14. The enclosure of  claim 13 , wherein the aluminum alloy substrate is a 6000 series alloy or a 7000 series alloy. 
     
     
       15. The enclosure of  claim 13 , further comprising:
 a sealant that seals openings of the pores such that the light-reflecting particles are sealed within the anodized layer. 
 
     
     
       16. The enclosure of  claim 13 , wherein the pore walls define fragmented portions with greater concentrations of the light-reflecting fissures than an innermost region of the anodized layer. 
     
     
       17. The enclosure of  claim 13 , wherein the light-reflecting particles are formed by fragmenting a portion of the anodized layer. 
     
     
       18. The enclosure of  claim 7 , wherein the pores have diameters between about 100 nm and about 500 nm. 
     
     
       19. The enclosure of  claim 13 , wherein the light-reflecting fissures have non-parallel orientations with respect to the outermost surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims the benefit of U.S. Provisional Application No. 62/292,173, entitled “PROCESS FOR PRODUCING WHITE ANODIC OXIDE FINISH” filed on Feb. 5, 2016, the contents of which are incorporated by reference in its entirety for all purposes. 
    
    
     FIELD 
     The described embodiments relate to anodic layers and methods for forming anodic layers. More specifically, white appearing anodic layers and methods for providing a white appearance to anodic layers are described. 
     BACKGROUND 
     Anodizing is an electrochemical process that thickens a naturally occurring protective oxide on a metal surface. An anodizing process involves converting part of a metal surface to an anodic layer. Thus, an anodic layer becomes an integral part of the metal surface. Due to its chemical inertness and hardness, an anodic layer can provide corrosion resistance and wear protection for an underlying metal. In addition, an anodic layer can enhance a cosmetic appearance of the metal surface. For example, the anodic layer can have a porous microstructure that can be infused with dyes to impart a desired color to the anodic layer. 
     Conventional methods for coloring anodic layers include dyeing the anodic layers. These techniques take advantage of the porous microstructures of anodic layers in that the pores that are formed within the anodic layers during the anodizing process can be infused with dyes and subsequently sealed. These techniques, however, have not been able to achieve an anodic layer with a white appearance as conventional white colorants (pigments) are generally relatively large compared to other types of dyes, and are therefore difficult to infuse within the pores of anodic layers. 
     SUMMARY 
     This paper describes various embodiments related to coloring anodized substrates. The anodized substrates can be characterized as having a visibly white appearance. 
     According to one embodiment, a method for forming an anodized substrate having a white appearance is described. The method includes forming fissures within pore walls of a porous anodic layer, the pore walls defining pores that are arranged within the porous anodic layer. The method further includes removing an outer portion of the porous anodic layer such that a remaining portion of the porous anodic layer includes at least some of the fissures. 
     According to another embodiment, a method for providing a white appearance to an anodized substrate, is described. The anodized substrate includes a porous anodic layer derived from a metal substrate, the porous anodic layer including pores defined by pore walls. The method includes exposing the porous anodic layer to an etching solution such that fissures form within the pore walls of the porous anodic layer and removing an outer portion of the porous anodic layer such that a remaining portion of the porous anodic layer includes at least some of the fissures. 
     According to yet another embodiment, an anodized substrate having a white appearance is described. The anodized substrate includes a metal substrate and a porous anodic layer that includes pores defined by pore walls, where the fissures are formed within the pore walls. 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The included drawings are for illustrative purposes and serve only to provide examples of possible structures and arrangements for the disclosed inventive apparatuses and methods for their application to computing devices. These drawings in no way limit any changes in form and detail that can be made to the embodiments by one skilled in the art without departing from the spirit and scope of the embodiments. The embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements. 
         FIGS. 1A-1D  illustrate perspective views of various devices having metallic surfaces that can be protected using the anodic oxide coatings described herein. 
         FIGS. 2A-2C  illustrate cross section views of an anodized substrate undergoing a series of steps for forming an anodized substrate having a white appearance, according to some embodiments. 
         FIG. 3  illustrates a cross section view of an anodized substrate prior to forming fissures in an anodized porous layer, according to some embodiments. 
         FIG. 4  illustrates a cross section view of the anodized substrate prior to an outer portion of the anodized porous layer being removed, according to some embodiments. 
         FIG. 5  illustrates a cross section view of the anodized substrate subsequent to an outer portion of the anodized porous layer being removed, according to some embodiments. 
         FIG. 6  illustrates an apparatus suitable for forming fissures in the anodized porous layer, according to some embodiments. 
         FIG. 7  illustrates a flowchart indicating a process for forming an anodized substrate having a white appearance, according to some embodiments. 
         FIGS. 8A-C  illustrate exemplary images of a perspective view of the anodized substrate subsequent different steps performed, according to some embodiments described herein. 
         FIG. 9  illustrates an exemplary image of a cross section view of the anodized substrate, according to some embodiments described herein. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure describes various embodiments of anodized surfaces and methods for forming anodized surfaces. Certain details are set forth in the following description and figures to provide a thorough understanding of various embodiments of the present technology. Moreover, various features, structures, and/or characteristics of the present technology can be combined in other suitable structures and environments. In other instances, well-known structures, materials, operations, and/or systems are not shown or described in detail in the following disclosure to avoid unnecessarily obscuring the description of the various embodiments of the technology. Those of ordinary skill in the art will recognize, however, that the present technology can be practiced without one or more of the details set forth herein, or with other structures, methods, components, and so forth. 
     This application describes anodized layers that are white in appearance and methods for forming such anodized layers. In general, white is the color or the appearance of objects that diffusely reflect all visible wavelengths of light incident on the object. Methods described herein provide internal surfaces within the anodized layer that can diffusely reflect substantially all wavelengths of visible light incident on the anodized layer, thereby imparting a white appearance to the anodized layer. The anodized layer can act as a protective layer in that it can provide corrosion resistance and surface hardness for the underlying substrate. The white anodized layer is well suited for providing a protective and attractive surface to visible portions of a consumer product. For example, the anodized layer and methods described herein can be used for providing protective and cosmetically appealing exterior portions of metal enclosures and casings for electronic devices. 
     One technique for forming an anodized layer having a white appearance involves an approach where the porous microstructures of the anodized layer are modified to form fissures within the porous microstructure. This technique involves forming fissures formed within walls of the pores. The fissures formed within the walls of the pores can scatter or diffuse incident visible light coming from a top surface of the substrate, giving the anodized layer a white appearance as viewed from the top surface of the substrate. 
     As used herein, the terms anodic film, anodized film, anodic layer, anodized layer, anodic layer, anodic oxidized layer, oxide film, oxidized layer, and oxide layer are used interchangeably and refer to any appropriate oxide layers. The anodic layers are formed on metal surfaces of a metal substrate. The metal substrate can include any of a number of suitable metals. In some embodiments, the metal substrate includes pure aluminum or aluminum alloy. In some embodiments, suitable aluminum alloys include 1000, 2000, 5000, 6000, and 7000 series aluminum alloys. 
     The methods described herein can be used to form durable and cosmetically appealing coatings for metallic surfaces of consumer devices.  FIGS. 1A-1D  show consumer products that can be manufactured using methods described herein. Each of the products shown in  FIGS. 1A-1D  include housings that are made of metal or have metal sections.  FIG. 1A  illustrates a portable phone  102 .  FIG. 1B  illustrates a tablet computer  104 .  FIG. 1C  illustrates a smart watch  106 .  FIG. 1D  illustrates a portable computer  108 . 
     Aluminum alloys are often a choice metal material due to their light weight and ability to anodize and form a protective anodic oxide coating that protects the metal surfaces from scratches. The anodic oxide coatings can be colorized to impart a desired color to the metal housing or metal sections, thereby adding numerous cosmetic options for product lines. 
     Conventional anodic oxide coloring techniques involve infusing dyes, such as organic dyes, within the pores of the anodic oxide. It is difficult, however, to create an anodic oxide finish that has a white color since white pigments particles are relatively large and difficult to adequately incorporate within an anodic oxide. Described herein are coloring techniques that can provide anodic oxide finishes to metal substrate, such as those on housing of devices  102 ,  104 ,  106  and  108 , having a white appearance. 
       FIGS. 2A-2C  illustrate a cross section of the anodized substrate  200  undergoing a sequence of processing steps for providing a white appearance to the anodized substrate  200 , in accordance with some embodiments.  FIG. 2A  illustrates the anodized substrate  200  having a porous anodic layer  208  subsequent to an anodizing process. The porous anodic layer  208  can be formed using an anodizing process whereby a portion of the metal substrate  202  is oxidized and converted to a corresponding metal oxide. Pores  220  are formed throughout the porous anodic layer  208 .  FIG. 2A  further shows a non-porous barrier portion  210  (i.e., does not include pores), which is formed during the anodizing process. In general, pores  220  are elongated voids that are formed within the metal oxide  224  during the anodizing process. Pores  220  are defined by pore walls  212  and a top surface  222  of the porous anodic layer  208 . 
       FIG. 2B  illustrates an anodized substrate  200  subsequent to performing a whitening process, in accordance with some embodiments. The whitening process generally includes forming nanometer-scale fissures  240  within pore walls  212  of the pores  220 . In some embodiments, fissures  240  are formed by exposing porous anodic layer  208  to an etching solution. The etching solution etches away some of the metal oxide  224  at the pore walls  212 , thereby thinning pore walls  212 , particularly at the outermost regions of the porous anodic layer  208 . In some embodiments, fissures  240  can correspond to voided regions within pore walls  212 , and which have surfaces generally oriented orthogonal with respect to the top surface  222 . In other embodiments, fissures  240  can refer to a cleave or split between two adjacent portions of the pore wall  212  such that a depression or division is formed between the two adjacent portions of the pore wall  212 . Because of their non-parallel orientation with respect to the top surface  222 , fissures  240  can diffusely reflect light incident the top surface  222 , thereby imparting a white appearance to the anodized substrate  200 . The whitening aspects of fissures  240  will be discussed in detail below with reference to  FIG. 4 . In addition to forming fissures  240 , however, the etching process can also cause pore walls  212  at outer regions of anodic layer  208  to become tapered and fragmented—referred to as fragmented portion  204 —which can compromise the structural integrity of anodic layer  208 . In particular, the fragmented portion  204  can become highly porous and very susceptible to cracking and breakage. 
     To address this aspect, in some embodiments, the fragmented portion  204  is removed.  FIG. 2C  illustrates an anodized substrate  200  subsequent to a process for removing the fragmented portion  204  such that the fissured portion  206  is left behind. Fissured portion  206  still includes fissures  240  such that the anodic layer  208  retains its white appearance without a structurally unsound top surface  222 . This removal process can be carried out using, for example, a finishing process, such as a polishing, lapping, or buffing process, which is described in detail below with reference to  FIG. 7 . In some embodiments, the finishing process causes metal oxide particles  216 , corresponding to displaced material from metal oxide  224 , to be forced within pores  220  and settle at bottom portions  230  of the pores  220 . Particles  216  can also diffract light and add a white appearance to anodic layer  208 . 
       FIG. 3  illustrates a cross section view of the anodized substrate  300  prior to implementing the above-described whitening process. Anodized substrate  300  includes porous anodic layer  308 , which is positioned over the metal substrate  302 . The metal substrate  302  can include any of a number of suitable materials. In some embodiments, metal substrate  302  includes pure aluminum or aluminum alloy. In other embodiments, metal substrate  302  includes pure titanium or a titanium-based alloy. Porous anodic layer  308  can include a number of pores  320  which are arranged longitudinally along the length of the porous anodic layer  308 . In some embodiments, the pores  320  may be arranged substantially parallel to each other. In one example, the porous anodic layer may have a thickness between about 5 micrometers to about 20 micrometers. In other examples, the porous anodic layer  308  can have a thickness between about 8 micrometers to about 15 micrometers. The thickness of metal substrate  302  can vary depending on particular applications. Generally, the metal substrate  302  is thicker than porous anodic layer  308 . However, in some embodiments, the metal substrate  302  is thinner than porous anodic layer  308 . Thus,  FIG. 3  is not necessarily drawn to scale. 
     Pores  320  of the porous anodic layer  308  can be formed by exposing metal substrate  302  to an electrolytic oxidative process in anodic bath solution—generally referred to as anodizing. For most anodizing processes, pores  320  are generally substantially parallel in orientation with respect to each other and substantially perpendicular with respect to the top surface  322  of the porous anodic layer  308 . The width (or diameter) and shape of each of pores  320  can vary depending on the type of anodizing process used. In general, the width of the pores  320  is in the scale of nanometers. In some embodiments, such as type II anodizing processes, a sulfuric acid is used. For typical type II anodizing, the width of each of pores  320  typically ranges between about 10 nanometer and 20 nanometers. In other embodiments, the anodizing process is performed in phosphoric acid and/or oxalic acid solution, which can result in anodic layer  308  having wider pores (e.g., between about 100 nm to about 500 nm in width) compared to anodizing in sulfuric acid solution (e.g., type II anodizing). The voltage used during the anodization process will vary depending on the type of anodizing solution and other process parameters. In particular embodiments, an applied voltage of greater than 50 volts is used. In one embodiment, a phosphoric acid solution is used and a voltage of about 150 volts is used. It should be noted that pores  320  that are too wide could impact the structural integrity of the porous anodic layer  308 . In a particular embodiment, a phosphoric acid anodizing process using a voltage of between about 80 volts and 100 volts is used to form a porous anodic layer  308  having a target thickness of about 10 micrometers. In some embodiments, an oxalic acid anodizing process using a voltage of between about 20 volts to about 120 volts is used. 
       FIG. 3  illustrates that pores  320  are separated and defined by wall segments  314  of the pore walls  312  of the porous anodic layer  308 . Wall segments  314  are made of metal oxide material.  FIG. 3  shows that a non-porous barrier portion  310  can be positioned between the metal substrate  302  and the porous anodic layer  308  according to some embodiments. The non-porous barrier portion  310  refers to an oxidized layer of the metal substrate  302 , which does not include pores  320 . 
     In many applications, porous anodic layer  308  is substantially transparent to the underlying metal substrate  302 . That is, a majority of light incident on the porous anodic layer  308  passes through the porous anodic layer  308  and reaches the underlying metal substrate  302 . To illustrate, light ray  350  entering the top surface  322  of the porous anodic layer  308  can pass through porous anodic layer  308  and be reflected or refracted by the top surface of the metal substrate  302 . Light ray  352  entering another portion of the top surface  322  of the porous anodic layer  308  can pass through the porous anodic layer  308  and be reflected or refracted at a different angle by the top surface of the metal substrate  302 . 
       FIG. 4  illustrates a cross section view of the anodized substrate  400  subsequent to a procedure where a number of fissures  440  are formed within the walls  412  that define the pores  420  as a result of an etching process. The specific etching process which will be described in more detail with reference to  FIGS. 6-7 . As described above, the etching process can create a fragmented portion  404  and a fissured portion  406 .  FIG. 4  illustrates that the fragmented portion  404  is positioned above the fissured portion  406 . In other words, the fragmented portion  404  is positioned closer to the top surface  422  of the porous anodic layer  408  to provide the porous anodic layer  408  with a substantially white appearance. 
     Generally, the fragmented portion  404  can refer to the section of the porous anodic layer  408  where the outer regions of the pore walls  412  are removed such as to form a generally tapered or pointed shape of the pore walls  412 . The shape of the substantially parallel structure of the pores  420  of the porous anodic layer  408  can be significantly changed as a result of the etching process. In other words, a section of the fragmented portion  404  having a generally tapered shape may have previously been a generally linear or parallel structure which was perpendicular to the metal substrate  402  and non-porous portion prior to the etching process. The fissured portion  406  can refer to the section of the porous anodic layer  408  where the outer regions of the pore walls  412  are not thinned or reduced to such an extent as to form a tapered shape of the pores  420 .  FIG. 4  is illustrative that although fissures  440  may be formed within the walls  412  of the fissured portion  406 , the substantially parallel structure of the pores  420  of the fissured portion  406  prior to the etching process remains unaffected. Fissures  440  can generally refer to a portion of the pore wall  412  having an absence of oxide material or hollowed out material, such as a craze, a groove, or a furrow according to some embodiments. In other embodiments, fissures  440  can refer to portions of the pore wall  412  having cracks or clefts formed within the pore wall  412  as a result of the etching process. In other embodiments, fissures  440  can refer to two adjacent portions of the pore wall  412  having a cleave or a split formed between the two adjacent portions of the pore wall  412  such that a depression or division is formed between the two adjacent portions. 
     During the etching process, the pore walls  412  can become reduced as a result of exposure to the etching solution such that a thinning effect is more prevalent at the pore walls  412  closer towards the top surface  422 . By etching away at the pore walls  412  closer to the top surface  422 , the fragmented portion  404  can form pores  420  having a generally tapered shape such that the average width of a pore  420  at the top surface  422  is wider than an average width of a portion of the same pore  420  that is below the top surface  422 . In some embodiments, the etching solution etches away some of the metal oxide  424  around pore walls  412 , thereby thinning pore walls  412 , particular at outer regions of porous anodic layer  408 . As shown in  FIG. 4 , this creates fissures  440  within anodic layer  408 . Since fissures  440  are generally oriented orthogonally with respect to the top surface  422 , these fissures  440  can diffusely reflect light incident at the top surface  422 , thereby imparting a white appearance to anodized substrate  400 . In addition to forming fissures  440 , however, the etching process can also cause pore walls  412  at outer regions of anodic layer  408  to become tapered and fragmented—referred to as fragmented portion  404 —which can compromise the structural integrity of anodic layer  408 . In particular, fragmented portion  404  can become highly porous and very susceptible to cracking. The fissures  440  can be included in a regular or irregular pattern within the walls  412 . In some examples, the fissures  440  can have a generally triangular, linear, rectangular shape, or the like. According to some embodiments, depending upon the specific parameters of the etching solution used, the fissures  440  can be formed within only a portion of the length of the pore wall  412 . In other embodiments, the fissures  440  can be formed along the entire length of the pore wall  412 .  FIG. 4  shows that each pore  420  can be separated from another pore  420  via a wall segment  414  of the porous anodic layer  408 . In some examples, the fissures  440  of the pore walls  412  can be nanometer-scale sized. For example, the fissures  440  may have a length with a range between 1 nanometer and 30 nanometers according to some embodiments. According to other embodiments, the length of each of the fissures  440  can have a range between 5 nanometers and 20 nanometers. In other examples, the fissuring of the pore walls  412  may be nanometric-scale relative to the pores  420  of the porous anodic layer  408 , where the pores  420  can be macro-scale sized. In other words, the size of each of the fissures  440  can be substantially smaller than the size of the pores  420 . 
       FIG. 4  shows that the non-porous barrier portion  410  can be unaffected by the etching process, such that the non-porous barrier portion  410  remains positioned between the metal substrate  402  and the porous anodic layer  408  according to some embodiments. In some embodiments, the thickness of the non-porous barrier portion  410  may be unaffected by the etching process. 
       FIG. 4  illustrates that the formed fissures  440  may be more heavily concentrated across the pore walls  412  of the fragmented portion  404  compared to the fissures  440  formed within the pore walls  412  of the fissured portion  406 . According to one example, a first section of a pore wall  412  of the fissured portion  406  may have a fewer number or a reduced concentration of fissures  440  relative to a different, second section of the same pore wall  412  of the fragmented portion  404 . For example, a first section of a pore wall  412  can include four fissures  440 , while a second section of the same wall of the pore  420  can include a single fissure  440 . A higher concentration of fissures  440  may be present at sections of the pore walls  412  that are closer to the top surface  422 , which may be a result of the fragmented portion  404  having increased exposure to the etching solution. As a result, the fragmented portion  404  can include a relatively high number of fissures  440  as a result of the etching solution etching away at the outer regions of the pore walls  412  and thinning the pore walls  412 . Although in some instances, it may be possible for the first section of the pore wall  412  of the fissured portion  406  to have the same number (or concentration) of fissures  440  or a greater number of fissures  440  (or concentration of) relative to a second section of the same pore wall  412  of the fragmented portion  404 . 
     According to some embodiments, it may be preferable to intentionally remove a portion of at least one of the fragmented portion  404  or the fissured portion  406  in order to increase the structural rigidity of the porous anodic layer  408 . As discussed, the presence of the number of fissures  440  formed within the pore walls  412  of the porous anodic layer  408  may decrease the structural rigidity of the porous anodic layer  408 . In some embodiments, it may be preferable to intentionally remove portions of the porous anodic layer  408  having fissures  440  (either concurrently or subsequent) with the etching procedure so as to reduce the structural frailty of the anodized substrate  400 . 
       FIG. 4  illustrates that the fissures  440  provide a light scattering medium that diffusely reflects a number of visible wavelengths of light incident on the top surface  422  of the porous anodic layer  408  such that light ray  450  is scattered by the fissures  440  before reaching the metal substrate  402 . As a result, by diffusely scattering visible light wavelengths, the top surface  422  can have a substantially white appearance.  FIG. 4  illustrates how another light ray  452  is scattered by the fissures  440  at a different angle than the light ray  450 . Another light ray  454  is illustrated as being scattered by the fissures  440  at a different angle than the light rays  450 ,  452 . In this manner, the fissures  440  can act as a light scattering medium so as to provide a white appearance to the porous anodic layer  408  even after the fragmented portion  404  is removed. 
     In some embodiments, the pores  420  of the porous anodic layer  408  can be optionally sealed using a sealing process. Sealing closes the pores  420  such that any oxidized fragments of the fragmented portion  404  or the fissured portion  406  are retained within the porous anodic layer  408 . In one embodiment, the sealing process includes hydrothermal sealing of the anodic oxide, which can be used for sealing the porous anodic layer  408  and exploits the swelling of amorphous aluminum oxide as it is hydrated when immersed in hot aqueous solutions (e.g., greater than 80° C.) or when it is exposed to steam. In one embodiment, the porous anodic layer  408  is exposed to a 5 g/l solution of nickel acetate at a temperature of 97° C. for a duration of 25 minutes. 
       FIG. 5  illustrates a cross section view of an anodized substrate  500  subsequent to removing an outer portion of the porous anodic layer  408  or removing the entire fragmented portion (e.g., ref  404 ,  FIG. 4 ) according to some embodiments. In other embodiments, only a portion of the fragmented portion  404  is removed such that a portion of the fragmented portion  404  continues to remain following the procedure. While forming fissures  440  within the porous anodic layer  408  may be induced to cause the porous anodic layer  408  to have a white appearance, the etching process may induce fragmentation and physical damage to the pore walls  412  as indicated by the fragmented portion. Accordingly, a technique is provided to reduce the physical instability of the porous anodic layer  408  by removing a portion of the fragmented portion  404  such that a more stable anodized substrate can be provided while still retaining some of the fissures  440  in order to continue to provide a white appearance of the porous anodic layer  408 . As a result,  FIG. 5  illustrates that although the fragmented portion  404  is removed, fissures  540  still remain in the pore walls  512  of the porous anodic layer  508 . As such, the anodized substrate  500  may still be enabled to provide a substantially white appearance while having an increased structural rigidity subsequent to the removal process. 
     In some embodiments, a portion of the fragmented portion  404  that is removed can range from a length of between 1 micrometer to 20 micrometers. In other embodiments, the portion of the fragmented portion  404  that is removed can range from a length between 5 micrometers and 15 micrometers. In other embodiments, the portion of the fragmented portion  404  that is removed can range from a length between 10 micrometers and 15 micrometers. In other embodiments, the portion of the fragmented portion  404  that is removed can range from a length between 3 micrometers and 5 micrometers.  FIG. 5  illustrates that removing the entire fragmented portion  404  reveals the fissured portion  506  such that an exterior surface of the fissured portion  506  can be referred to as the top surface  522  of the porous anodic layer  508 . In other words, when viewing the porous anodic layer  508  from a top view, only the fissured portion  506  will be visibly apparent. 
     According to some embodiments, in the remaining porous anodic layer  508 , there can be a greater concentration of fissures  540  formed within the walls  512  of the pores  520  towards the top surface  522  of the porous anodic layer  508  than towards the lower portion of the porous anodic layer  508 . As such, because the inner or lower portion of the porous anodic layer  508  has fewer fissures  540 , the lower portion of the porous anodic layer  508  can also be considered more structurally sound or rigid proximate than the top surface  522  of the porous anodic layer  508 . For instance, the lower portion of the porous anodic layer  508  can exhibit higher strength and hardness, as may be evaluated through techniques such as nano-indentation. 
       FIG. 5  illustrates a cross section view of an anodized substrate  500  having an porous anodic layer  508  according to some of the embodiments described herein.  FIG. 5  illustrates a metal substrate  502  and a porous anodic layer  508  that is formed by oxidizing a portion of the metal substrate  502 . The porous anodic layer  508  can be composed from metal oxide  524  formed from the anodization process. As shown in  FIG. 5 , the border between the metal substrate  502  and the porous anodic layer  508  may be substantially regular or of uniform thickness according to some embodiments. In other embodiments, the border between the metal substrate  502  and the porous anodic layer  508  may be substantially irregular or of non-uniform thickness. 
     Even after the fragmented portion  404  is removed,  FIG. 5  illustrates that the fissures  540  of the fissured portion  506  can continue to provide a light scattering medium that diffusely reflects substantially all visible wavelengths of light incident on the top surface  522  of the porous anodic layer  508  such that the top surface  522  has a substantially white appearance.  FIG. 5  illustrates how a light ray  550  entering from the top surface  522  of the porous anodic layer  508  is diffusely scattered by the fissures  540 .  FIG. 5  illustrates how another light ray  552  entering from the top surface  522  of the porous anodic layer  508  is diffusely scattered by the fissures  540  at a different angle. In this way, the fissures  540  can act as a light scattering medium so as to provide a white appearance to the porous anodic layer  508  even after the fragmented portion  404  is removed. In other words, the fissures  540  of either the fragmented portion  404  or the fissured portion  506  can provide a light scattering medium that diffusely reflects substantially all visible wavelengths of light incident that are emitted onto the top surface  522  of the porous anodic layer  508 . 
       FIG. 5  further illustrates that subsequent to removing the fragmented portion  404 , the fragmented metal oxide particles or residue  516  that are formed as a result of the removal step, can be displaced within the walls  512  of the pores  520 . In some examples, the displaced metal oxide particles  516  can reside within the outer extremities of the pores  520 . In other examples, the displaced metal oxide particles  516  can fill a minority, majority, or an entirety of the pore  520 . In other examples, there can be an absence of metal oxide particles  516  displaced within the pores  520  subsequent to the procedure. In some embodiments, the metal oxide particles  516  may impart a substantially white appearance to the porous anodic layer  508  since they can diffusely reflect substantially all wavelengths of visible light. For example, a light ray  554  can enter the pores  520  and reflect off of the metal oxide particles  516 . The particles  516  positioned at the bottom portions  530  of the pores  520  can act as a light scattering medium for diffusing incident visible light entering from the top surface  522  thus giving the bottom portions  530  of the pores  520  an opaque and white appearance. In addition to contributing to light scattering, the displaced metal oxide particles  516  can enhance or improve the structural rigidity of the porous anodic layer  508  as well as seal the pores  520  of the porous anodic layer  508 . The metal oxide particles  516  can provide additional material (e.g., oxide and hydroxide) to plug the pore openings such as to raise the material density of the porous anodic layer  508  to compensate for fissures  440  which were previously removed. The metal oxide particles  516  can also be physically or mechanically wedged into the pores  520 , and can additionally be entrapped during the swelling of the pore walls  512  during a hydrothermal sealing process. As a result, the metal oxide particles  516  can also swell in volume during the hydrothermal sealing process, as a result of hydration, such that the metal oxide particles  516  become permanently fused as part of the pore walls  512 . 
     Although  FIG. 5  illustrates the metal oxide particles  516  as being generally spherical in shape, the particles  516  may also include a combination of a spherical, rectangular, triangular shape, and the like. In addition, the metal oxide particles may be generally macro-scale sized or nano-scale sized. 
     The terms outer portion of the porous anodic layer  508 , a portion of the fragmented portion  404 , and the entire fragmented portion  404  can be used interchangeably while referring to removing the outer portion of the porous anodic layer  508 . 
     Subsequent to the step of removing the fragmented portion  404  of the porous anodic layer  508 , the pores  520  can be optionally sealed using a sealing process. In other embodiments, the step of removing the fragmented portion by a lapping or sealing process can itself mechanically seal a portion of the pore openings via plugging the pores  520  with fragments or particles  516  of metal oxide as well as possibly polishing media. In some embodiments, supplementary sealing can enhance the sealing of the pores  520 . Sealing closes the pores  520  such that pores  520  can retain the metal oxide particles  516 . The sealing process can swell the pore walls  512  of porous anodic layer  508  and close the pore openings of the pores  520 . Any suitable sealing process can be used. In one embodiment, the sealing process includes exposing the anodized substrate  500  to a solution containing hot water with nickel acetate. In some embodiments, the sealing process forces some of metal oxide particles  516  to be displaced from top portions of pores  520 . As shown, in  FIG. 5 , portions of metal oxide particles  516  at top portions of pores  520  have been displaced during the sealing process to reside within the bottom portions  530  of pores  520 . Thus, portions of metal oxide particles  516  still remain within the pores  520  even after the sealing process. Indeed, metal oxide particles  516  are themselves susceptible to swelling during hydrothermal sealing. Accordingly, subjecting the porous anodic layer  508  to a hydrothermal sealing process can further reinforce the structural rigidity of the porous anodic layer  508 , reinforce the sealing of the pores  520 , and reinforce the physical retention of metal oxide particles  516  within the pores  520 . A hydrothermal sealing process can refer to a process in which amorphous metal oxides such as aluminum oxide are exposed to a hot aqueous solution or steam, resulting in the formation of hydroxides or oxy-hydroxides of lower density (and higher volume) than the original oxide. This process can be used for swelling the pore walls  512  in order to plug the pores  520 . One example of the sealing process includes immersing the porous anodic layer  508  in a hot aqueous solution (e.g., greater than 80° C.) or when it is exposed to steam. In one embodiment, the porous anodic layer  508  is exposed to about 5 g/l solution of nickel acetate at a temperature of 97° C. for a duration of 25 minutes. 
       FIG. 6  illustrates an exemplary apparatus for forming fissures  240  in the porous anodic layer  208  according to some embodiments.  FIG. 6  shows that an anodized substrate  600  is placed in an etching bath or solution  650  in a tank or container  670 . The container  670  can hold the etching solution  650 , while a portion of the anodized substrate  600  is submerged in the etching solution  650 . An etching (e.g., acidic or alkaline etching) is used to create a textured surface or fissures  240  within the porous anodic layer  208  of the anodized substrate  600 , which can be retained by the walls  212  of the pores  220 . According to some examples, the anodized substrate  600  can be etched through exposure to a Al 2 (SO 4 ) 3  solution for 25 minutes at 60° C. In another example, the anodized substrate  600  can be etched through exposure to an alkaline Na 2 CO 3  solution for 20 minutes at 30° C. 
       FIG. 7  illustrates a process  700  for forming a porous anodic layer  208  having a substantially white appearance according to some embodiments. As shown in  FIG. 7 , the method  700  can begin at step  702 , where a surface pretreatment (or pre-texturizing) is optionally performed on the metal substrate  202 . The surface treatment can be a polishing process that creates a mirror polished substrate surface, corresponding to a generally uniform surface profile. In other embodiments, the surface treatment is an etching process that creates a textured surface that can have a matte appearance. In some examples, creating a textured surface can be the result of at least one of blasting, etching, or chemically polishing the surface of the metal substrate  202 . Suitable etching processes include an alkaline etch, where the metal substrate  202  is exposed to an alkaline solution (e.g., NaOH) for a predetermined time period for creating a desired texture. Acidic etching solutions (e.g., NH 4 HF 2 ) can also be used. Polishing techniques can include chemical polishing, which involves exposing the metal substrate  202  to acidic solution, e.g., sulfuric acid and phosphoric acid solutions. In some embodiments, the polishing includes one or more mechanical polishing processes. In some embodiments, a textured or roughened surface of the metal substrate  202  can be preferable for the purposes of imparting a uniform white appearance to the surface. In some embodiments where a final white or other bright appearance to the porous anodic layer  208  is desired, the metal substrate  202  is preferably polished rather than etched in order to create an underlying light reflective substrate surface. In other embodiments, where a dark color or shade is desired, the metal substrate  202  can be etched in order to purposely create an underlying light trap that traps incoming light. In some embodiments, the textured surface of the metal substrate  202  can also control the structure of the porous anodic layer  208  formed (see step  704 ) as well as influence the etching process used to form fissures  240  in the porous anodic layer (see step  706 ). 
     At step  704 , an anodization step is performed on the metal substrate  202 . During the anodizing process, a porous anodic layer  208  having a number of pores  220  formed longitudinally throughout the porous anodic layer  208  can be formed. In some embodiments, the anodizing is performed in a sulfuric acid solution, such as a type II anodizing process. In some embodiments, the anodizing is performed in a phosphoric acid or oxalic acid solution, which can form wider pores  220  than sulfuric anodizing processes. During the anodizing process, a porous anodic layer  208  having a porous layer and a non-porous barrier portion  210  can be formed. 
     At step  706 , a number of fissures  240  can be formed within the pore walls  212  of the porous anodic layer  208 . In some embodiments, an etching (e.g., acidic or alkaline etching) is used to form the fissures  240  within the pore walls  212 . The etching solution can also etch away some of the metal oxide around the pore walls  212 , thereby thinning pore walls  212 , particularly at the outermost regions of the porous anodic layer  208 . Since fissures  240  are generally oriented orthogonally with respect to top surface  222 , these fissures  240  can diffusely reflect light incident top surface  222 , thereby imparting a white appearance to anodized substrate. In addition to forming fissures  240 , however, the etching process can also cause pore walls  212  at outer regions of the porous anodic layer  208  to become tapered and fragmented—referred to as fragmented portion  404 —which can compromise the structural integrity of the porous anodic layer  208 . 
     At step  708 , pores  220  of the porous anodic layer  208  can be optionally sealed via a sealing process according to some embodiments. In some instances, sealing the pores  220  may be preferable in that sealing closes the pores  220  such that any oxidized fragments of either the fragmented portion  204  or the fissured portion  206  are retained within the porous anodic layer  208 . In some instances, the sealant can settle towards the bottom portions  230  of the pores  220  of the fissured portion  206 . The sealant may trap displaced oxidized materials of the porous anodic layer  208  between the sealant and the bottom portions  230  of the pores  220 . This sealing process hydrates the metal oxide material of the pore walls  212 , thereby increasing the structural integrity of the porous anodic layer  208 . In general, the sealing process does not, however, remove the light reflecting fissures  240 . In one embodiment, the sealing process includes exposing the porous anodic layer  208  to a solution containing hot water with nickel acetate for a period of time (e.g., about 25 minutes). 
     In other embodiments, sealing the pores  220  prior to the step of removing the outer portion of the porous anodic layer  208  may not be preferable because the sealant may actually prevent displaced metal oxide particles  216  originating from the fragmented portion  204  from being displaced into the pores  220  of the porous anodic layer  208 . As detailed with reference to  FIG. 5 , fragmented metal oxide particles  516  can be formed and displaced as a result of the removal step. In some embodiments, the metal oxide particles  516  may impart a desirable substantially white appearance to the porous anodic layer  508  since they can diffusely reflect substantially all wavelengths of visible light. However, sealing the pores  520  prior to the step of removing the outer portion can prevent the displaced metal oxide particles  516  from being trapped within the pores  520 . In some embodiments, the displaced metal oxide particles  516  or residues can contribute to the density of the porous anodic layer  508 , e.g., by filling the pores  520  via mechanical packing. The metal oxide particles  516  can be susceptible to swelling, and may also contribute to expanding the pore walls  512  for providing a robust seal for the pores  520 . 
     While forming fissures  240  within the porous anodic layer  208  imparts a white appearance to the porous anodic layer  208 , the etching process can cause severe physical damage to the pore walls  212  at external or top portions of the porous anodic layer  208 , referred to above as a fragmented portion  204  of the porous anodic layer  208 . At step  710 , some or the entire fragmented portion  204  of the porous anodic layer  208  can be removed. By removing some or the entire fragmented portion  204 , the remaining porous anodic layer  208  has improved structural integrity and is more resistant to breakage and cracking. The pore walls  212  of the remaining portion, i.e., the fissured portion  206 , will include fissures  240  created from the etching process. These fissures  240  can provide a light scattering medium that diffusely reflects visible wavelengths of light incident on a top surface  222  of the porous anodic layer  208 , thereby providing a white appearance to the porous anodic layer  208  as viewed from a top surface  222  of the porous anodic layer  208 . In some embodiments, the removal process includes a finishing process, such as a polishing, lapping and/or buffing process. In some cases, the finishing process can force fragments of metal oxide material from the fragmented portion  204  to displace within the pores  220  of the porous anodic layer  208 . These fragments or particles  216  can also serve as light scattering medium for diffracting incoming light. 
     At step  712 , the pores  220  of the porous anodic layer  208  may be optionally sealed using a sealing process e.g., hydrothermal sealing. The sealing process can seal the open pores  220  by hydrating the metal oxide material of the pore walls  212 . The sealing process can be important to keep contaminants such as water, dirt and oil out of the pores of the porous anodic layer  208 , which can affect the visual appearance of the substrate. In addition, the sealing prevents water from reaching and corroding the underlying metal substrate  202 . Furthermore, the sealing process can trap metal oxide fragments or particles  216  displaced into the pores  220  as a result of the step of removing the fragmented portion during step  710 . In some embodiments, the pores  220  can be sealed via a similar process used to seal the pores  220  as described in step  708 . In some instances, the metal oxide particles  216  can themselves become hydrated and contribute to the robustness of the seal formed during the hydrothermal sealing step in order to boost the structural rigidity of the porous anodic layer  208 . 
     At step  714 , a finishing operation (e.g., a surface treatment) can be optionally applied to the porous anodic layer  208  to further adjust surface finish and cosmetics. For example, a polishing or buffing operation can be used to give the top surface  222  of the porous anodic layer  208  a uniform and shiny appearance. 
       FIGS. 8A-8C  illustrate exemplary electron microscopy images of the anodized substrate during different stages of processing the metal substrate.  FIG. 8A  illustrates a perspective view of the anodized substrate  800  at 250× magnification and a perspective view of the anodized substrate at 1000× magnification.  FIG. 8A  illustrates a perspective view of the top surface  822  of the anodized substrate  800  including a porous anodic layer  808  prior to imparting a white appearance to the anodized substrate  800 . As shown in  FIG. 8A , a number of pores  820  are arranged proximate to the top surface  822  of the porous anodic layer  808 . 
       FIG. 8B  illustrates a perspective view of an etched anodized substrate  802  at 250× magnification and a perspective view of the etched anodized substrate  802  at 1000× magnification.  FIG. 8B  illustrates a perspective view of the top surface  822  of the etched anodized substrate  802  including a porous anodic layer  808  subsequent to a step for forming fissures  840  within the walls of the pores. According to one embodiment, a number of fissures  840  can be formed within the walls of each pore during an etching process. 
       FIG. 8C  illustrates a perspective view of a polished anodized substrate  804  at 250× magnification and a perspective view of the polished anodized substrate  804  at 1000× magnification.  FIG. 8C  illustrates a perspective view of the top surface  822  of the polished anodized substrate  804  including a porous anodic layer  808  subsequent to a step of removing an outer portion or top surface  822  of the porous anodic layer  808  according to some embodiments. In other embodiments, the fragmented portion can be either partially or entirely removed. When the fragmented portion or top surface  822  of the porous anodic layer  808  is removed, the fissured portion becomes exposed as the top surface of the porous anodic layer  808 . The porous anodic layer  808  can include pores  820 . 
     According to other embodiments, the polished anodized substrate of  FIG. 8C  can also be polished or buffed in order to smooth the top surface  822  of the porous anodic layer  808 . 
       FIG. 9  illustrates an electron microscopy image of the anodized substrate  900  including a porous anodic layer  908  at a magnification level of 4000×. In some embodiments,  FIG. 9  illustrates the porous anodic layer  908  and the metal substrate  902  subsequent to the step for forming fissures within the pore walls (e.g., etching step). In other embodiments,  FIG. 9  illustrates the porous anodic layer  908  subsequent to any of the other aforementioned steps described.  FIG. 9  shows that a number of fissures  940  extend within the pore walls, where the pores are arranged longitudinally within the porous anodic layer  908 . As shown in  FIG. 9 , the pores  920  extend longitudinally through only a portion (i.e., not the entirety) of the porous anodic layer  908  such that a cross-section or layer of the porous anodic layer  908  does not include pores. In addition,  FIG. 9  illustrates that the fissures  940  formed within the pore walls are more highly concentrated (or numerous) towards the top surface of the porous anodic layer  908 . Towards the inner or lower portion of the porous anodic layer  908 , the concentration of fissures  940  continues to taper off at a constant or exponential rate. Furthermore,  FIG. 9  shows that the metal substrate (e.g., aluminum)  902  can include a varied or non-uniform thickness relative to the border between the porous anodic layer  908  and the substrate.  FIG. 9  further illustrates a series of peaks  950  that are disposed on the top surface of the metal substrate  902 . The pore  920  formed through the porous anodic layer  908  can correspond with an corresponding peak  950  of the metal substrate  902 . For instance, the associated peak  950  of the metal substrate  902  can be formed as a result of increased amounts of oxide particles being displaced onto the surface of the metal substrate  902 . According to some embodiments, each pore  920  is formed as a result of an increased number of particles (not illustrated) converging towards the bottom portion of the pores  920 . Towards the bottom portion of the pores  920  can be an increased concentration of particles such that the oxidized particles of the pores build up over the metal substrate  902  to form a peak  950 . The described pores  920  can be generally broad and shallow in shape compared to pores of typical porous anodic layers. 
       FIG. 9  further illustrates that the porous anodic layer  908  can include a fragmented portion and a fissured portion (not illustrated). The fragmented portion can be similar to the structure of the fragmented portion (e.g., ref  404  shown in  FIG. 4 ). The fissured portion can be similar to the structure of the fissured portion (e.g., ref  406  shown in  FIG. 4 ).  FIG. 9  further illustrates that a series of pores  920  are disposed within the top surface of the porous anodic layer  908  and penetrate through an inside portion of the porous anodic layer  908 .  FIG. 9  further illustrates a series of peaks  950  that are disposed on the top surface of the fragmented portion. Each pore  920  formed through the porous anodic layer  908  can correspond with a corresponding peak  950  of the metal substrate  902 . For instance, the peak  950  of the metal substrate  902  can be formed as a result of increased amounts of oxide particles being displaced onto the surface of the metal substrate  902 . According to some embodiments, the peaks  950  can be formed during the anodization process as a result of further penetration of the pores  920  through the inner portion of the porous anodic layer  908  which leads to an increased formation of oxidized particles that form over the metal substrate  902  to form peaks  950 . 
     In some embodiments,  FIG. 9  can be representative of the anodized substrate subsequent to a step for forming fissures within the walls of the pores (e.g., etching step). However, the anodized substrate illustrated in  FIG. 9  can be representative of the anodized substrate during any particular state, and is not intended to limit the anodized substrate to a particular step. 
     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 the specific embodiments described herein are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the 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: 20170127
Publication Date: 20210216
Grant Date: 20210216
Priority Date: 20160205
Inventors: CURRAN, JAMES A.
MCDONALD, Daniel T.
NOVAK, SEAN R.
Assignee: APPLE INC
CPC Classifications: [{"code": "C25D11/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "C25D11/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "C25D11/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/249986", "inventive": false, "first": false, "tree": "[]"}, {"code": "C25D11/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "C25D11/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "C25D11/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "C25D11/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "C25D11/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "C25D11/246", "inventive": true, "first": true, "tree": "[]"}, {"code": "C25D11/246", "inventive": true, "first": true, "tree": "[]"}, {"code": "C25D11/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "C25D11/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/249978", "inventive": false, "first": false, "tree": "[]"}, {"code": "C25D11/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "C25D11/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "C25D11/246", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T428/249978", "inventive": false, "first": false, "tree": "[]"}, {"code": "C25D11/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "C25D11/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "C25D11/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/249986", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 58722186