Patent Publication Number: US-2016232946-A1

Title: Self-assembled monolayer coating for disc drive manufacture

Description:
BACKGROUND 
     Hard disc drives are common information storage devices having a series of rotatable discs that are accessed by magnetic reading and writing elements. These data elements, commonly known as transducers, or merely as a transducer, are typically carried by and embedded in a slider that is held in a close relative position over discrete data tracks formed on a disc to permit a read or write operation to be carried out. 
     As distances between the slider and the disc decrease, due to the ever-growing desire to reduce the size of the disc drive and to pack more data per square inch, the potentially negative impact due to contamination on the slider increases. Unwanted contaminants on the slider can adversely affect fly height behavior, such as with elevated or decreased fly height, create fly asymmetry in roll or pitch character, produce excessive modulation, and even result in head-disc crashing or contact, all possibly due to contaminant build up on the slider. All of these mechanisms result in degraded performance of the read or write operation of the head (e.g., skip-writes, modulated writers, weak writes, clearance stability and settling, and incorrect clearance setting). 
     Contaminants can be introduced on to the slider and to other components of the disc drive during any number of manufacturing or processing steps. What is needed is a mechanism to remove and/or control contaminants from contaminating components of the disc drive. 
     SUMMARY 
     One particular implementation described herein is a method of making a disc drive assembly comprising a plurality of components, the method comprising providing a self-assembled monolayer coating on at least one piece of process equipment that contacts at least one of the plurality of components. 
     Another particular implementation is a method comprising inhibiting contact transfer from a piece of process equipment to a component of a disc drive assembly by providing a self-assembled monolayer coating on the piece of process equipment. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. These and various other features and advantages will be apparent from a reading of the following detailed description. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWING 
       The described technology is best understood from the following Detailed Description describing various implementations read in connection with the accompanying drawings. 
         FIG. 1  is a top plan view of an example disc drive assembly. 
         FIG. 2  is a side view of a schematic example of a lapping process. 
         FIG. 3  is a perspective view of an example of a slider carrier tray. 
         FIG. 4  is a perspective view of an example head-gimbal assembly (HGA) carrier tray. 
         FIG. 5  is a perspective view of an example media carrier. 
     
    
    
     DETAILED DESCRIPTION 
     As discussed above, hard disc drive assemblies include a slider that is designed and configured to glide on an air bearing over a magnetic data storage disc. Contaminants, on the slider, on the disc, or elsewhere in the disc drive assembly, can interfere with the proper performance of either or both the “read” operation and the “write” operation of the disc drive. Often, the source of the contaminants is a source external to the disc drive itself; the contaminants are introduced to the disc drive during the manufacturing process of the disc drive, typically by contact transfer from a piece of equipment used during the manufacturing and/or assembly process. Another source of contaminant is the piece of processing equipment or the drive component itself; abrasion between the drive component and the processing piece can readily result in particulate contaminants. The present disclosure describes providing a self-assembled monolayer (SAM) coating on at least one piece of process equipment that contacts at least one of the plurality of components of the disc drive during manufacture and/or assembly of the components. The self-assembled monolayer coating inhibits the transfer of any contaminants that might be on the piece of process equipment to the component, either by inhibiting the presence of the contaminant on the piece or by inhibiting release of the contaminant from the piece. The self-assembled monolayer coating, which is not found in the eventual assembled disc drive assembly, reduces contact transfer of contaminants during the manufacturing and/or assembly processes. 
     In the following description, reference is made to the accompanying drawing that forms a part hereof and in which are shown by way of illustration at least one specific implementation. The following description provides additional specific implementations. It is to be understood that other implementations are contemplated and may be made without departing from the scope or spirit of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense. While the present disclosure is not so limited, an appreciation of various aspects of the disclosure will be gained through a discussion of the examples provided below. 
       FIG. 1  illustrates a perspective view of an exemplary magnetic disc drive  100 . Disc drive  100  includes a base and a top cover that combine to form a housing  101  in which is located one or more rotatable magnetic data storage media or discs  102 . Disc  102  rotates about a spindle center or a disc axis of rotation  104  during operation. Disc  102  includes an inner diameter  106  and an outer diameter  108  between which are a number of concentric data tracks  110 , illustrated by circular dashed lines. Data tracks  110  are substantially circular and are made up of regularly spaced bits  112 , indicated as dots or ovals on disc  102 . It should be understood, however, that the described technology may be employed with other types of storage media, including continuous magnetic media, discrete track (DT) media, etc. 
     Information may be written to and read from bits  112  on disc  102  in different data tracks  110 . A head-gimbal assembly (HGA)  120  having an actuator axis of rotation  122  supports a slider  124  with a transducer in close proximity above the surface of disc  102  during disc operation. When a pack of multiple discs  102  is utilized, each disc  102  or medium surface has an associated slider  124  which is mounted adjacent to and in communication with its corresponding disc  102 . 
     The surface of slider  124  closest to and opposite to disc  102  is called the air-bearing surface (ABS). In use, head-gimbal assembly  120  rotates during a seek operation about the actuator axis of rotation  122  to position slider  124  and head-gimbal assembly  120  over a target data track of data tracks  110 . As disc  102  spins, a layer of air forms between slider  124  and the surface of disc  102 , resulting in slider  124  ‘flying’ above disc  102 . The transducer on slider  124  then reads or writes data to bits  112  in the target data track  110 . 
     Each of the components of disc drive  100 , components such as slider  124 , head-gimbal assembly  120 , disc  102 , housing  101 , etc., is individually formed and then assembled together to form disc drive  100 . The total process to form disc drive  100  has hundreds of steps, virtually every process step being a potential source of contamination in the assembled disc drive  100 . 
     If at least one of the pieces of the processing equipment that comes into contact with a component of disc drive  100  has a SAM coating thereon, contaminants in the assembled disc drive assembly are reduced, due to less or no contaminants being stuck on upstream processing equipment and thus in disc drive  100 . 
     For example, slider  124  goes through a detailed process of forming (e.g., depositing) the various features of slider  124 , cutting or slicing, and lapping to achieve the desired dimensions. After slider  124  is formed, it is washed and transported. 
     After forming (e.g., depositing) the various features of thousands of sliders  124  on a wafer, the wafer is cut or sliced into smaller pieces to facilitate further processing; in some implementations, the wafer is sliced in chunks, the chunks are sliced into bars, and after lapping, the bars are eventually sliced into individual sliders. Each of the slicing or cutting processes is a source of contaminants, both particular and chemical (e.g., cutting oil or solvent). Any or all of the process equipment that contacts (e.g., handles, slices, cuts) the wafer or its subparts (e.g., chunks, bars) can have a SAM coating thereon, to reduce the occurrence of contaminants in the assembled disc drive assembly, due to less or no contaminants being stuck on the wafer and thus upon the final slider. 
     While in the bar stage, the bar is lapped (i.e., abraded) on a rotating lapping plate to provide a random motion of the slider bar over the lapping plate and randomize plate imperfections across the head surface. Some lapping plates have a non-abrasive horizontal working surface and are used in conjunction with a slurry of abrasive particles (e.g., diamonds), whereas other lapping plates have abrasive particles (e.g., diamonds) embedded in or on the horizontal working surface.  FIG. 2  shows an example of a generic lapping system  200 . 
     System  200  has a lapping plate or platen  202  having a working surface  204 . Present on working surface  204  is an abrasive coating  206 . A slider row bar  208  (cut from a wafer and containing a plurality of sliders) is held in contact with abrasive coating  206  by an arm assembly  210 . In use, platen  202  is rotated relative to slider row bar  208  and bar  208  is held in pressing engagement against abrasive coating  206  by assembly  210 . The abrading action of abrasive coating  206  removes material from slider bar  208  and provides the desired shape to the slider bar, which includes low crown effects, good stripe control, and good pitch. 
     For conventional lapping processes, the process includes three sequential steps: a rough lapping step, a fine lapping step, and a kiss lapping step. The rough lapping step, when as much as 20 microns of material might be removed from the slider bar, is an aggressive lapping process that requires good adhesion of the slider bar to the carrier tool in order to avoid a large twist being lapped into the bar. Conversely, the kiss lapping step is a final polishing and precision shaping step, much less aggressive than the rough lapping step, usually removing no more than 100 nanometers of material. 
     Turning to the inset of  FIG. 2 , abrasive coating  206  is present on working surface  204 . Abrasive coating  206  has a plurality of abrasive composites  212  held on to working surface  204  by an adhesive  214 . Each abrasive composite  212  has abrasive particles  216  retained in a matrix  218 . For a rough lapping step, abrasive particles  216  (e.g., diamonds) are usually about 1 to about 5 micrometers in size, in some implementations as large as 10 micrometers; for a fine lapping step, abrasive particles  216  are usually about 0.1 to about 1 micrometer in size; for a kiss lapping step, abrasive particles  216  are usually less than 0.1 micrometer (100 nm). It is not uncommon for abrasive composites  212  to crack or break, releasing abrasive particles  216  and/or pieces of matrix  218 . These contaminants may stick, e.g., by van der Waals or other weak forces, to the bar and eventual sliders. 
     After formed, individual sliders are placed and stored in trays, such as tray  300  of  FIG. 3 ; the sliders are also washed, to remove contaminants from the forming, slicing, and lapping processes. The particular tray  300  of  FIG. 3  is suitable both as a cleaning tray and as a carrier tray, although in other implementations different trays are used for washing than storage. Tray  300  can be a plastic (polymeric) or plastic-coated device. 
     Tray  300  has a planar body  302  forming a central section having a top surface  304  and an opposite bottom surface (not seen), body  302  having an outer perimeter  306  and a perimeter flange  308 . Top surface  304  has a plurality of cavities  310  therein, each for receiving a slider therein. Cavities  310  have dimensions selected to obtain adequate retention of the slider in cavity  310  during the cleansing process and/or the transport process. 
     From tray  300 , the sliders are attached to a head-gimbal assembly and then assembled into a disc drive. Until the sliders are assembled into the disc drive, they come into contact with one or more trays, wash and rinse solutions and brushes that are used to wash and rinse hundreds of sliders, vacuum and/or end effectors that move the trays, tweezers, clamps, slider tray carriers, and other pick-up instruments that physically move the sliders. 
     If tray  300 , or any of the pieces of the processing equipment (e.g., tweezers, etc.) that comes into contact with the slider, has a SAM coating thereon, contaminants in the assembled disc drive assembly are reduced, due to less or no contaminants being stuck on upstream processing equipment and thus upon the slider. 
     The various other components of the disc drive also undergo multi-step processing prior to being assembled into a disc drive. For example, the head-gimbal assembly (e.g., head-gimbal assembly  120  of  FIG. 1 ) is formed, e.g., punched or stamped from a metal sheet and then bent to the desired configuration, and then placed into a tray for storage and/or cleansing. In some implementations, the head-gimbal assembly is formed from multiple components; for example, a head-gimbal assembly includes a load beam, a gimbal limiter, a piezoelectric (PZT) member, and electronics. During forming and after, the various components of the head-gimbal assembly are contacted by molds, brakes, end effectors, tweezers, clamps, and other pick-up instruments. 
     A slider is operably and electrically attached to the actuator assembly after the components have been formed. The slider, head-gimbal assembly (often alternately referred to a head-gimbal suspension assembly), and load beam, with other components, may be first placed in a ‘precising nest’ or other jig that accurately places and aligns the various components. The slider is particularly susceptible to contact transfer of contaminants when inserted into the precising nest (e.g., a small, stainless steel cavity) and held against registration surfaces. Once the slider is properly positioned, adhesive is dropped on the back of the slider, and the gimbal-suspension assembly is placed on and adhered to the slider. Such a process of inserting the slider into a cavity and pushing it against the reference surfaces is very susceptible to contamination contact transfer. 
     If the precising nest or other jig, or any other piece of processing equipment (e.g., tweezers, etc.) that comes into contact with the slider, head-gimbal assembly, etc. has a SAM coating thereon, contaminants in the assembled disc drive assembly are reduced. 
       FIG. 4  illustrates a carrier tray  400  for a plurality of assembled head-gimbal assemblies (HGAs). Tray  400  has a body  402  having a top surface  404  and an opposite bottom surface (not seen). Top surface  404  has a plurality of cavities  410  therein, each for receiving an HGA therein; an HGA  420  is illustrated in one of the cavities. Cavities  410  have dimensions selected to obtain adequate retention of HGA  420  in cavity  410  during any storage process and transport process. Once assembled, HGA  420  often undergoes a quality test, to confirm, e.g., proper electrical connections. 
     If tray  400  or any of the pieces of the processing equipment (e.g., tweezers, testing equipment, etc.) that comes into contact with HGA  420  has a SAM coating thereon, contaminants in the assembled disc drive assembly are reduced. 
     The magnetic media or disc (e.g., disc  102  of  FIG. 1 ) also undergoes multiple operations and movements before being installed into the disc drive. Generally, a metal or ceramic disc blank is coated with magnetic material; such process involves several handling operations, including moving the disc into the coating apparatus and out from the coating apparatus. Often, a hard protective overcoat (e.g., diamond-like carbon) is applied over the magnetic material, which also involves several handling operations. In each of the handling operations, the disc is susceptible to contact transfer of contaminants. In some methods, the disc is contacted by end effectors or other pick-up instruments and is carried and/or stored in media trays or media carriers. 
     At various stages in the process, the media or disc is placed into a tray or carrier.  FIG. 5  illustrates an example of a media carrier  500 . Such a carrier  500  may be used for storing and/or for transporting a plurality of discs. The particular carrier  500  has a body  502  with opposite side walls  504 ,  506  and opposing end walls  508 ,  510 . Spaced along side walls  504 ,  506  and projecting inward are ridges  512  that define slots  514 , each for receiving a disc therein. The two side walls  504 ,  506  have an inwardly converging bottom portions that correspond to the shape of the disc. Carrier  500  may include a cover (not shown). 
     If carrier  500  or any of the pieces of the processing equipment (e.g., clamps, etc.) that comes into contact with the media has a SAM coating thereon, contaminants in the assembled disc drive assembly are reduced. 
     The disc drive assembly includes numerous other components such as, e.g., a spindle or shaft that supports the magnetic discs, a voice coil or other motor that moves the actuator assembly to align the slider on the data tracks, a housing or cover over the voice coil motor, flexible electronics that connect the slider to a processor via the actuator assembly, one or more filters, and the housing that encases all the disc drive components. 
     Any self-assembled monolayer (SAM) coating or coatings can be applied to the processing equipment. The coating is comprised of at least one SAM material and can be either a high surface energy coating or a low surface energy coating. The coating can be oleophobic or oleophilic, hydrophobic or hydrophilic. The SAM coating inhibits the contact transfer of any contaminants that might be on a piece of process equipment to the component that will eventually be found in the assembled disc drive assembly. In some implementations, the SAM coating inhibits the presence of contaminant on the piece of process equipment; that is, contaminant is less likely to stick or attach to the piece of process equipment. In other implementations, the SAM coating inhibits release of the contaminant from the piece of process equipment; that is, contaminant is less likely to release from the piece of process equipment and be transferred to the disc drive component. 
     A SAM coating is most beneficial on plastic (polymeric) processing equipment, as those pieces have a greater tendency to attract and retain contaminants thereon, contaminants that can then be transferred to the disc drive components. However, a SAM coating on metal, ceramic, composite processing equipment will also benefit the reduction of contaminants on the disc drive components. Both plastic and metal may have surface pores, which the SAM coating may seal, thus eliminating possible locations for contaminants to reside. 
     In some implementations, a SAM coating reduces contaminants by inhibiting the creation of contaminants. For example, a SAM coating on the bottom wall of a cavity of a slider carrier tray (e.g., cavity  310  of tray  300 , of  FIG. 3 ) may increase or decrease the friction between the slider and the cavity, depending on the material of the slider, the material of the tray, and the SAM used. A SAM can be selected to increase the friction between the slider and the tray, thus inhibiting the slider from sliding within the cavity, and thus reducing the possibility of abrading the cavity and/or the slider and releasing contaminants. Alternately, a SAM can be selected to decrease the friction between the slider and the tray, thus facilitating easy movement of the slider within the cavity, and thus reducing the possibility of abrading the cavity and/or the slider and releasing contaminants. In a similar manner, a SAM coating can be applied to any surface of a cavity of an HGA tray (e.g., cavity  410  of tray  400 , of  FIG. 4 ). 
     The terms “self-assembled monolayer,” “SAM,” and variants thereof, refer to a thin monolayer of surface-active molecules provided (e.g., adsorbed and/or chemisorbed) on a surface to produce chemical bonds therebetween. The molecules may have been present, for example, in a reaction solution or a reactive gas phase. 
     The term “low surface energy” and variations thereof, as used herein, refers to the tendency of a surface to resist wetting (high contact angle) or adsorption by other unwanted materials or solutions. In a low surface energy SAM, the functional terminal groups of the molecules are chosen to result in weak physical forces (e.g., Van der Waals forces) between the coating and contaminant. A low surface energy SAM allows for partial wetting or no wetting of the resulting SAM coating (i.e., a high contact angle between a liquid and the coating). Conversely, “high surface energy” refers to the tendency of a surface to increase or promote wetting (low contact angle) or adsorption of the surface of contaminants. In a high surface energy SAM, the functional terminal groups of molecules are chosen to result in a stronger molecular force between the coating and contaminant. If both a high surface energy coating and a low surface energy coating are present, the surface energies are relative. Values that are typically representative of “low surface energy” are in the range of 5-30 dyne/cm and high surface energy materials are relatively higher than this range, typically anything greater than 30 dyne/cm. 
     The phrase “oleophilic SAM” and variations thereof as used herein refers to a SAM having an oleophilic functional end group, such as saturated hydrocarbons. Other particular examples of suitable terminal groups include alkyls with 1-18 carbon atoms in addition to other unsaturated hydrocarbon variants, such as, aryl, aralkyl, alkenyl, and alkenyl-aryl. Additionally, materials with amine terminations, as well as carbon oxygen functional groups such as ketones and alcohols, will exhibit oleophilic properties. 
     The phrase “oleophobic SAM” and variations thereof as used herein refers to a SAM having an oleophobic functional end group, such as halosilanes and alkylsilanes. Particular examples of suitable halosilane and alkylsilane terminal groups include fluorinated and perfluorinated. In some implementations, an oleophobic SAM is also hydrophobic, thus being amphiphobic. 
     The precursor compound for forming the SAM coating on the piece of processing equipment contains molecules having a head group and a tail with a functional end group. Common head groups include thiols, silanes with hydrolizable reactive groups (e.g., halides: {F, Cl, Br, I}, and alkoxys: {methoxy, ethoxy, propoxy}, phosphonates, etc. Common tail groups include alkyls with 1-18 carbon atoms in addition to other unsaturated hydrocarbon variants, such as, aryl, aralkyl, alkenyl, and alkenyl-aryl. In addition, the hydrocarbons materials listed above can be functionalized with fluorine substitutions, amine terminations, as well as carbon oxygen functional groups such as ketones and alcohols, etc., depending on the desired properties of the resulting SAM coating. SAMs are created by chemisorption of the head groups onto the substrate material (i.e., in this application, onto the piece of processing equipment) from either a vapor or liquid phase, by processes such as immersion or dip coating, spraying, chemical vapor deposition (CVD), micro-contact printing, dip-pen nanolithography, ink-jet printing, etc. The head groups closely assemble on the material with the tail groups extending away from the material. The self-assembled monolayer can be, for example, an organosilane (e.g. alkyl trichlorosilane, fluorinated alkyl trichlorosilane, alkyl trialkyloxysilane, fluorinated alkyl trialkyloxysilane, etc.). 
     The precursor compound of the SAM may be present in any conventionally-used organic solvent, inorganic solvent, water, or any mixture thereof. Examples of suitable organic solvents may include, but are not limited to, alcohols (e.g., methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, t-butyl alcohol, isobutyl alcohol, and diacetone alcohol); ketones (e.g., acetone, methylethylketone, methylisobutylketone); glycols (e.g., ethyleneglycol, diethyleneglycol, triethyleneglycol, propyleneglycol, butyleneglycol, hexyleneglycol, 1,3-propanediol, 1,4-butanediol, 1,2,4-butantriol, 1,5-pentanediol, 1,2-hexanediol, 1,6-haxanediol); glycol ethers (e.g., ethyleneglycol dimethyl ether, and triethyleneglycol diethyl ether); glycol ether acetates (e.g., propylene glycol monomethyl ether acetate (PGMEA)); acetates (e.g., ethylacetate, butoxyethoxy ethyl acetate, butyl carbitol acetate (BCA), dihydroterpineol acetate (DHTA)); terpineols (e.g., trimethyl pentanediol monoisobutyrate (TEXANOL)); dichloroethene (DCE); chlorobenzene; and N-methyl-2-pyrrolidone (NMP). 
     The concentration of the precursor compound in the solution may be determined by those skilled in the art according to the intended applications and purposes and may be in the range of about 5 to about 20 mM. An immersion step may be performed without particular limitation and may be carried out at room temperature for about 20 to 120 minutes. Alternately, other methods may be used. 
     An example of a commercially available low surface energy SAM is 1H,1H,2H,2H-perfluorodecyltrichlorosilane (also known as, heptadecafluoro-1,1,2,2-tetrahydro-decyl-1-trichlorosilane) [CAS: 78560-44-8], of course, other low surface energy SAM materials could be used. In general the class of fluorinated organosilane derivatives would work as low energy SAM materials. Other examples of commercially available low surface energy SAMs include: trifluoropropyltrimethoxysilane, heneicosafluorododecyltrichlorosilane, nonafluorohexyltrimethoxysilane, methyltrichlorosilane, ethyltrichlorosilane, propyltrimethoxysilane, hexyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrichlorosilane, dodecyltrichlorosilane, and octadecyltrichlorosilane. 
     An example of a commercially available high surface energy SAM is (3-aminopropyl)-trimethoxysilane [CAS: 13822-56-5]. Of course, other high surface energy SAM materials could be used. The general class of organosilanes with amine, alcohol, or mercapto substituents would provide for a high surface energy SAM, relative to the above. Some commercially available examples include: (3-Mercaptopropyl)trimethoxysilane, methyl 11-[dichloro(methyl)silyl]undecanoate, acetoxyethyltrichlorosilane, and vinyltriethoxysilane. 
     Examples of commercially available oleophilic SAM materials fall within the general class of 1-18 carbon alkylsilanes with a hydrolyzable reactive group (e.g., F, Cl, Br, and I) and alkoxys (e.g., methoxy, ethoxy, and propoxy). Such chemicals are readily available, for example, from Gelest and Sigma Aldrich, and include methyltrichlorosilane, ethyltrichlorosilane, propyltrimethoxysilane, hexyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrichlorosilane, dodecyltrichlorosilane, and octadecyltrichlorosilane. In addition to the alkyl class, other functional SAMs, such as the following, are also are advantageous: 3-aminopropyltrimethoxysilane, methyl 11-[dichloro(methyl)silyl]undecanoate, acetoxyethyltrichlorosilane, vinyltriethoxysilane, and nonafluorohexyltrimethoxysilane. 
     Various oleophobic SAM materials are commercially available and suitable for use on pieces of processing equipment. 
     As indicated above, by coating at least one piece of processing equipment with SAM, contaminants in the assembled disc drive assembly are reduced, due to less or no contaminants being transferred to the components of the disc drive from the processing equipment. For example, a hydrophobic SAM coating on a piece of processing equipment will inhibit particles from sticking to the coated piece; an oleophobic SAM coating will inhibit lubricant and other oil-based materials from adhering to and/or wetting the coated piece. With less contaminants available to be transferred to the components, results in less contaminants in the assembled disc drive. 
     In some implementations, a base or seed layer may be applied to the piece of processing equipment prior to applying the SAM coating. A base or seed layer may be included to improve the adhesion and/or orientation of the SAM coating to the piece, particularly when the piece has a surface material typically not amenable to SAM formation, or to provide additional or different properties to the piece. For example, plastic pieces are known to off-gas, particularly if a plasticizer is present in the plastic. A base or seed layer may seal the piece, inhibiting of contamination (e.g., plasticizer) from originating from the plastic piece. Additionally, plastic pieces are typically not amenable to SAM reaction and formation due to low oxide content of the material; a base or seed layer can be tailored to make the plastic piece a better substrate for SAM formation. Additionally or alternately, a base or seed layer may provide thermal stability to the SAM coating. Additionally or alternately, a base or seed layer may act as a barrier layer to inhibit transport of humidity and solvent vapors to and from the processing equipment. Still further, a base or seed layer on a metal processing piece may be corrosion resistant. Examples of suitable base or seed layers include oxides (e.g., metal oxides). Of course, a base or seed layer may provide other benefits. 
     Various implementations of a self-assembled monolayer (SAM) coating on a piece of process equipment have been described above. The SAM coating is provided on a piece of process equipment that contacts a component (e.g., slider, actuator, media, etc.) of a disc drive during manufacture and/or assembly of the component. The SAM inhibits the contact transfer of any contaminants that might be on the piece of process equipment to the component, either by inhibiting the presence of the contaminant on the piece or by inhibiting release of the contaminant from the piece. The SAM is not found in the eventual assembled disc drive assembly. 
     The above specification provides a complete description of the structure and use of exemplary implementations of the invention. The above description provides specific implementations. It is to be understood that other implementations are contemplated and may be made without departing from the scope or spirit of the present disclosure. The above detailed description, therefore, is not to be taken in a limiting sense. While the present disclosure is not so limited, an appreciation of various aspects of the disclosure will be gained through a discussion of the examples provided. 
     Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties are to be understood as being modified by the term “about.” Accordingly, unless indicated to the contrary, any numerical parameters set forth are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein. 
     As used herein, the singular forms “a”, “an”, and “the” encompass implementations having plural referents, unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. 
     Spatially related terms, including but not limited to, “bottom,” “lower”, “top”, “upper”, “beneath”, “below”, “above”, “on top”, “on,” etc., if used herein, are utilized for ease of description to describe spatial relationships of an element(s) to another. Such spatially related terms encompass different orientations of the device in addition to the particular orientations depicted in the figures and described herein. For example, if a structure depicted in the figures is turned over or flipped over, portions previously described as below or beneath other elements would then be above or over those other elements. 
     Since many implementations of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended. Furthermore, structural features of the different implementations may be combined in yet another implementation without departing from the recited claims.