Patent Publication Number: US-9893247-B2

Title: Light-emitting device including phosphorus layer covering side surfaces of substrate and light-emitting device package including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 13/297,809, filed on Nov. 16, 2011, which claims the benefit of Korean Patent Application No. 10-2010-0128607, filed on Dec. 15, 2010, the disclosures of which are incorporated herein in their entirety by reference. 
    
    
     BACKGROUND 
     1. Field 
     The present disclosure relates to a light-emitting device including a phosphor layer, a light-emitting device package employing the light-emitting device, a method of manufacturing the light-emitting device, and a method of packaging the light-emitting device. 
     2. Description of the Related Art 
     Light-emitting devices, for example, light-emitting diodes (LEDs) are semiconductor devices that may emit various light colors by forming a light-emitting source through a PN junction of a compound semiconductor. The LEDs have a long lifespan, may be made small and light, and have a strong light directivity, and thus the LEDs may be driven at a low voltage. Also, the LEDs are strong on impact and vibration, do not need to be preheated, may be driven in a simple way, and may be packaged in various forms, and thus the LEDs may be used for various purposes. 
     Recently, a blue LED and an ultra-violet (UV) LED formed using a nitride having a high physical and chemical characteristics have been introduced. Also, white light or other monochromatic light may be formed by using the blue LED or the UV LED and a phosphor material, and thus the application of the LEDs is becoming wider. 
     SUMMARY 
     Provided is a light-emitting device that may reduce chromaticity inferiorities of light emitted from side surfaces of a substrate and may obtain a uniform color quality of light, a light-emitting device package employing the light-emitting device, a method of manufacturing the light-emitting device, and a method of packaging the light-emitting device. 
     Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments. 
     According to an aspect of the present invention, a light-emitting device includes a light-transmissive substrate having a top surface, a bottom surface, and side surfaces; a light-emitting unit formed on the top surface of the light-transmissive substrate; and a phosphor layer covering all the side surfaces of the light-transmissive substrate. 
     The phosphor layer may cover the side surfaces and the bottom surface of the light-transmissive substrate. 
     A thickness of the phosphor layer may be in the range of about 30 to about 300 μm. 
     The light-transmissive substrate may be a sapphire substrate. 
     The light-emitting unit may emit blue light, and the phosphor layer may change the blue light to white light. 
     According to another aspect of the present invention, a light-emitting device package includes a package body including a terminal unit; a light-emitting device that includes: a light-transmissive substrate having a top surface, a bottom surface, and side surfaces; a light-emitting unit formed on the top surface of the light-transmissive substrate; and a phosphor layer covering all the side surfaces of the light-transmissive substrate, and mounted on the package body; and a wire for electrically connecting the light-emitting unit and the terminal unit. 
     The phosphor layer may cover the side surfaces and the bottom surface of the light-transmissive substrate. 
     A thickness of the phosphor layer may be in the range of about 30 to about 300 μm. 
     The light-emitting device package may further include a second phosphor layer covering the light-emitting unit. 
     The light-emitting unit may emit blue light, and the phosphor layer and the second phosphor layer may change the blue light to white light. 
     The light-transmissive substrate may be a sapphire substrate. 
     The light-emitting device may be packaged by using any one method selected from the group consisting of a pre-mold method, a wire-bonding method, and a flip-chip-bonding method. 
     According to another aspect of the present invention, a method of manufacturing a light-emitting device, the method includes transferring a plurality of light-emitting device chips, each including a light-transmissive substrate having a top surface, a bottom surface, and side surfaces and a light-emitting unit formed on the top surface of the light-transmissive substrate, on a transfer body so that side surfaces of the light-emitting device chips are spaced apart from one another and so that the light-emitting unit faces toward the transfer body; depositing a fluorescent material-containing resin to fill gaps between the plurality of light-emitting device chips, and then hardening the fluorescent material-containing resin; and forming the light-emitting device in which a phosphor layer covering all the side surfaces of the light-transmissive substrate is formed, by dicing the fluorescent material-containing resin hardened in the gap. 
     The transferring of the plurality of light-emitting device chips on the transfer body may include: dividing the plurality of light-emitting device chips from a wafer in which the plurality of light-emitting device chips are formed ; and classifying the divided light-emitting device chips by rank and transferring the classified light-emitting device chips on the transfer body. 
     The classifying and transferring of the divided light-emitting device chips may include: attaching the classified light-emitting device chips onto an adhesive tape so that side surfaces of the light-emitting device chips are spaced apart from one another and so that the bottom surface of the light-transmissive substrate faces toward the adhesive tape; and transferring the light-emitting device chips from the adhesive tape onto the transfer body. 
     The fluorescent material-containing resin may be deposited to fill the gaps between the plurality of light-emitting device chips and to cover the bottom surfaces of the light-transmissive substrates of the light-emitting device chips, and wherein the light-emitting device, in which the phosphor layer covering the side surfaces and the bottom surface of the light-transmissive substrate is formed, is formed by dicing the fluorescent material-containing resin hardened in the gap. 
     A thickness of the phosphor layer may be in the range of about 30 to about 300 μm. 
     The light-emitting unit may emit blue light, and the phosphor layer may change the blue light to white light. 
     The light-transmissive substrate may be a sapphire substrate. 
     According to another aspect of the present invention, a method of packaging a light-emitting device, the method includes mounting a light-emitting device, which includes a light-emitting unit and a light-transmissive substrate and in which a phosphor layer covering all the side surfaces of the light-transmissive substrate is formed, on a package body by using any one method selected from the group consisting of a pre-mold method, a wire-bonding method, and a flip-chip-bonding method; and forming a second phosphor layer by depositing a fluorescent material-containing resin on the light-emitting unit. 
     The phosphor layer may cover side surfaces of the light-transmissive substrate and a bottom surface that is an opposite surface to a top surface on which the light-emitting unit is formed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a schematic perspective view of a light-emitting device according to an embodiment of the present invention; 
         FIG. 2  is a cross-sectional view of a light-emitting unit of the light-emitting device of  FIG. 1 ; 
         FIGS. 3A through 3J  are diagrams for explaining a method of manufacturing the light-emitting device of  FIG. 1 ; 
         FIG. 4  is a cross-sectional view of a pre-mold type light-emitting device package, according to an embodiment of the present invention; 
         FIGS. 5A and 5B  are cross-sectional views for explaining a method of packaging a light-emitting device according to a pre-mold method, according to embodiments of the present invention; 
         FIG. 6  is a cross-sectional view of a wire-bonding type light-emitting device package, according to an embodiment of the present invention; and 
         FIG. 7  is a cross-sectional view of a flip-chip-bonding type light-emitting device package, according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, the present invention will be described in detail by explaining exemplary embodiments of the invention with reference to the attached drawings. The same reference numerals in the drawings denote the same element. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. 
       FIG. 1  is a schematic perspective view of a light-emitting device  1  according to an embodiment of the present invention.  FIG. 2  is a cross-sectional view of a light-emitting unit  20  of the light-emitting device of  FIG. 1 . Referring to  FIGS. 1 and 2 , the light-emitting device  1  includes a light-emitting device chip  100  and a phosphor layer  200 . 
     The light-emitting device chip  100  may be a light-emitting diode chip. The light-emitting diode chip may emit blue, green, red light, etc. according to a material of a compound semiconductor for forming the light-emitting diode chip. The light-emitting device chip  100  may include a substrate  10  and the light-emitting unit  20  that is formed on the substrate  10  and emits light. 
     The substrate  10  may be a light-transmissive substrate including a top surface  11 , side surfaces  12 , and a bottom surface  13 . The light-transmissive substrate may be, for example, a sapphire substrate, a zinc-oxide (ZnO) substrate, a gallium nitride (GaN) substrate, a silicon carbide (SiC) substrate, or an aluminum nitride (AIN) substrate. 
     The light-emitting unit  20  is disposed on the top surface  11  of the substrate  10 . For example, the light-emitting unit  20  of a blue light-emitting diode chip may include an active layer  22  having a quantum well layer structure in which GaN and lnGaN are alternately formed, a P-type clad layer  23  in which a compound semiconductor formed of Al x Ga y N z  is formed on the active layer  22 , and an N-type clad layer  21  in which a compound semiconductor formed of Al x Ga y N z  is formed under the active layer  22 . Although not shown in  FIGS. 1 and 2 , a buffer layer may be interposed between the N-type clad layer  21  and the substrate  10  before growing the N-type clad layer  21  so as to increase lattice-matching between the N-type clad layer  21  and the substrate  10 . An N-electrode  24  and a P-electrode  25  are electrically connected to the N-type clad layer  21  and the P-type clad layer  23 , respectively. Although not shown in  FIGS. 1 and 2 , a bonding pad for a wire-bonding process may be formed on the N-electrode  24  and the P-electrode  25 . A structure of the light-emitting unit  20  illustrated in  FIG. 2  is just an example, and thus the present invention is not limited thereto. 
     In order to change light emitted from the light-emitting device chip  100 , for example, blue light, to white light, the phosphor layer  200  may be formed. The phosphor layer  200  may be a phosphor-containing resin formed by mixing fluorescent particles in a binder resin. The fluorescent particles may be a single species, and may be a plurality of species that are mixed at a predetermined ratio. The binder resin may be a polymer that may satisfy a high adhesive property, a high light-transmissive property, a high thermal resistance, a high light refractive index, a water tolerance, etc. For example, the binder resin may be an epoxy-based resin or silicon which is an inorganic polymer. The binder resin may include a silane-based material as an additive agent for increasing adhesion. Also, the binder resin may include various additive agents according to its purpose. The phosphor layer  200  may be formed by depositing a fluorescent-containing polymer on a predetermined position and hardening the fluorescent-containing polymer. A method of forming the phosphor layer  200  will be described in detail later. 
     Light generated from the light-emitting unit  20  of the light-emitting device chip  100  may exit upward from the light-emitting unit  20 . A part of the light may spread in the light-transmissive substrate  10  and then may exit through the side surfaces  12  of the substrate  10 . In order to change the color of light emitted through the side surfaces  12 , the light-emitting device  100  according to the current embodiment includes the phosphor layer  200  covering all the side surfaces  12  of the substrate  10 . The light emitted through the side surfaces  12  of the substrate  10  passes through the phosphor layer  200  to exit. Accordingly, for example, when blue light exits from the light-emitting device chip  100  and the phosphor layer  200  contains fluorescent particles for changing blue light to white light, the light exiting through the side surfaces  12  of the substrate  10  may be changed to white light having a high quality by passing through the phosphor layer  200 . 
     The phosphor layer  200  may be formed to cover the side surfaces  12  and the bottom surface  13  of the substrate  10 . The light-emitting device  1  may be formed on a circuit substrate through flip-chip bonding, and light may exit through the bottom surface  13  and the side surfaces  12  of the substrate  10 . In this case, the phosphor layer  200  may be formed to cover the side surfaces  12  and the bottom surface  13  of the substrate  10 . 
     A thickness of the phosphor layer  200  may be in the range of about 30 μm to about 300 μm. Thicknesses of the phosphor layer  200  covering the side surface  12  and the bottom surface  13  may be the same, but the present invention is not limited thereto. The phosphor layer  200  covering the side surfaces  12  and the bottom surface  13  may be determined to have thicknesses appropriate for changing light emitted from the light-emitting device chip  100  to light having a desired chromaticity. 
     Hereinafter, a method of manufacturing the light-emitting device  100  illustrated in  FIGS. 1 and 2  will be described. 
     First, the light-emitting device chip  100  in which the light-emitting unit  20  is formed on the substrate  10 , which is a light-transmissive substrate, is prepared. Referring to  FIG. 3A , the light-emitting device chip  100  may be provided in the form of a wafer in which a plurality of the light-emitting units  20  are disposed on the substrate  10  by performing a series of semiconductor processes. The substrate  10  is diced along a dicing line  40  by using a mechanical cutter or a laser cutter so as to individually obtain the light-emitting device chip  100 . The dicing line  40  is a virtual line for individually dividing the light-emitting device chips  100 . 
     The divided light-emitting device chips  100  may be classified by rank. That is, a light-emitting wavelength of the light-emitting device chip  100  is measured, and then light-emitting device chips  100  having a similar light-emitting characteristic may be classified. As such, a process of forming a fluorescent material to be described later may be performed by classifying the light-emitting device chips  100  having a similar light-emitting characteristic by rank. Thus, the light-emitting device  1  having a uniform chromaticity may be manufactured by controlling an amount of a fluorescent material-containing resin, a type of fluorescent particle, and an amount of the fluorescent particle for each rank. 
     Next, as illustrated in  FIG. 3D , the light-emitting device chips  100  are arranged on a transfer body  50  so that the light-emitting unit  20  faces downward. The transfer body  50  may be, for example, a UV tape having a thermal resistance. The light-emitting device chips  100  may be arranged on and then attached to the transfer body  50  by radiating UV light thereon. A gap G between the light-emitting device chips  100  may be determined in consideration of a thickness of the phosphor layer  200  to be formed on the side surfaces  12  of the substrate  10 . For example, the gap G may be obtained by adding an expected loss of the thickness of the phosphor layer  200  in a dicing process to be described later to twice the thickness of the phosphor layer  200  to be formed on the side surfaces  12  of the substrate  10 . 
     A process of arranging the light-emitting device chips  100  on the transfer body  50  may be performed by using the process illustrated in  FIGS. 3B and 3C . First, as illustrated in  FIG. 3B , the light-emitting device chips  100  are arranged on an adhesive tape  60  so that the bottom surface  13  of the substrate  10  faces downward. At this time, the side surfaces  12  of the substrate  10  of the light-emitting device chip  100  is spaced apart by the gap G from the adjacent side surface  12  of the adjacent substrate  10  of the adjacent light-emitting device chip  100 . Next, the adhesive tape  60  onto which the light-emitting device chips  100  are attached is reversed and disposed on the transfer body  50  so that the light-emitting unit  20  faces toward the transfer body  50 . Then, the adhesive tape  60  is separated from the bottom surface  13  of the substrate  10 . Thus, the light-emitting device chips  100  are transferred on the transfer body  50  so that the light-emitting units  20  face downward. The light-emitting device chips  100  are attached onto the transfer body  50  by radiating UV light on the transfer body  50 . The light-emitting device chips  100  may be arranged on the transfer body  50  by performing the above-described transfer process as illustrated in  FIG. 3D . 
     Next, a fluorescent material-containing resin is deposited on the gap G and is then hardened. In this process, for example, a compression mold method may be used. As illustrated in  FIG. 3E , the unhardened fluorescent material-containing resin is deposited on the gap G, and is then pressed and molded at a temperature of from about 100 to about 150 □. Then, the fluorescent material-containing resin filled in the gap G is cooled. In order to form the phosphor layer  200  up to the bottom surface  13  of the substrate  10 , a sufficient amount of fluorescent material-containing resin is deposited so as to cover the bottom surface  13  of the substrate  10  as illustrated in  FIG. 3F , and is then pressed, molded, and cooled. By performing the above-described process, a molding body  60   a  in which the fluorescent material-containing resin is molded on the side surfaces  12  of the light-emitting device chip  100  formed on the transfer body  50 , and a molding body  60   b  in which the fluorescent material-containing resin is molded on the side surfaces  12  and the bottom surface  13  of the light-emitting device chip  100  formed on the transfer body  50  may be obtained. 
     Next, the dicing process for individually dividing the light-emitting device  1  including the light-emitting device chip  100  and the phosphor layer  200  is performed. The dicing process may be performed by using, for example, a mechanical dicing method using a blade, a water-jet dicing method, a laser dicing method, or the like. In the dicing process, the molding bodies  60   a  and  60   b  may be transferred on a dicing tape  70 , as illustrated in  FIG. 3G or 3H . Then, the fluorescent material-containing resin is diced using, for example, a dicing blade  80 , and the light-emitting device  1  is separated from the dicing tape  70 . 
     By performing the above-described process, as illustrated in  FIGS. 3I and 3J , the light-emitting device  1  in which the phosphor layer  200  is formed on the side surfaces  12  of the substrate  10  and the light-emitting device  1  in which the phosphor layer  200  is formed on the side surfaces  12  and the bottom surface  13  of the substrate  10  may be obtained. The light-emitting device  1  having a desired chromaticity characteristic may be selected by performing a chromaticity measuring process before performing a packaging process to be described later. 
     The light-emitting device  1  manufactured by performing the above-described process is manufactured into a light-emitting device package by performing a packaging process to be used in a light source apparatus. Referring to  FIG. 4 , the light-emitting device package  2  includes the light-emitting device  1 , in which the phosphor layer  200  is formed on the side surfaces  12  or on the side surfaces  12  and the bottom surface  13 , and a package body  300  to which the light-emitting device  1  is coupled. The light-emitting device package  2  illustrated in  FIG. 4  is a pre-mold type package, and the package body  300  may include a lead frame  310  and a mold frame  320 . 
     The lead frame  310  may be manufactured by performing a pressing process and an etching process on a metal plate such as aluminum or copper. The lead frame  310  may include a mounting portion  311  and first and second terminal units  312  and  313 . The first and second terminal units  312  and  313  are electrically connected to the light-emitting unit  20  of the light-emitting device chip  100  by wires  331  and  332 , respectively. For example, the first terminal unit  312  may be connected to the P-electrode  25  by the wire  331 , and the second terminal unit  313  may be connected to the N-electrode  24  by the wire  332 . The first and second terminal units  312  and  313  are exposed by a mold frame  320  and apply current to the light-emitting device chip  100 . 
     A second phosphor layer  210  may be disposed on the light-emitting unit  20 . The second phosphor layer  210  may cover the light-emitting unit  20  and the top surface  11  of the substrate  10 . Also, the second phosphor layer  210  may cover a top surface of the phosphor layer  200 . The second phosphor layer  210  may be formed of a material that is the same as that of the phosphor layer  200 . 
     For example, when blue light is emitted from the light-emitting device chip  100  and the second phosphor layer  210  includes a fluorescent material for changing blue light to white light, light emitted upward from the light-emitting unit  20  is changed into white light by passing through the second phosphor layer  210  to exit. Also, since the blue light emitted through the side surfaces  12  of the substrate  10  passes through the phosphor layer  200 , the blue light may be changed to white light to exit. Accordingly, all the blue light emitted from the light-emitting device chip  100  passes through the phosphor layer  200  or the second phosphor layer  210 , and thus white light of a high quality may be obtained. 
     The mold frame  320  may be coupled to the lead frame  310  by performing, for example, an insert molding process. The mold frame  320  may be formed of, for example, an electrical insulating polymer. The mold frame  320  is formed to have a recessed shape so as to expose the mounting portion  311  and the first and second terminal units  312  and  313 . The light-emitting device package  2  has a structure in which the light-emitting device  1  is disposed on a bottom surface of a recess  340  that has a concave shape. 
     Hereinafter, a method of manufacturing the light-emitting device package  2  will be simply described with reference to  FIGS. 5A and 5B . 
     First, the lead frame  310  including the mounting portion  311  and the first and second terminal units  312  and  313  is formed by processing a metal plate. Then, the mold frame  320  is coupled to the lead frame  310  by performing, for example, an insert injection molding process, and thus the package body  300  is formed as illustrated in  FIG. 5A . 
     Next, as illustrated in  FIG. 5B , the light-emitting device  1  in which the phosphor layer  200  is formed on the side surfaces  12  or on the side surfaces  12  and the bottom surface  13  is mounted on the mounting portion  311 . Then, a wire-bonding process for electrically connecting the light-emitting unit  20  and each of the first and second terminal units  312  and  313  is performed by using the wires  331  and  332 . 
     Then, a process of forming the second phosphor layer  210  on the light-emitting unit  20  is performed by depositing a fluorescent material-containing resin on the light-emitting unit  20 . The fluorescent material-containing resin is deposited to cover the entire light-emitting unit  20 , preferably, may be deposited to cover the entire light-emitting unit  20 , the top surface  11  of the substrate  10 , and the phosphor layer  200 . Then, a hardening process is performed thereon, thereby manufacturing the light-emitting device package  2  illustrated in  FIG. 4 . A process of filling a light-transmissive protection resin in the recess  340  may further be performed as a subsequent process. 
     A method of forming the phosphor layer  200  and the second phosphor layer  210  by using a chip level dispensing (CLD) method may be considered. That is, in a process in which the light-emitting device chip  100  is formed instead of a process in which the light-emitting device package  2  is formed, a method of forming the phosphor layer  200  and the second phosphor layer  210  by depositing a fluorescent material-containing resin on an upper portion of the light-emitting device chip  100  may be considered. However, in the CLD method, the fluorescent material-containing resin is deposited on a surface of the light-emitting device chip  100  by using surface tension, and thus it is difficult to form the phosphor layer  200  on the side surfaces  12  of the light -emitting device chip  100 . Accordingly, blue light leaking through the side surfaces  12  of the substrate  10  is emitted without passing through the phosphor layer  200 , thereby causing chromaticity inferiorities of the blue light. Also, according to the CLD method, since the fluorescent material-containing resin is deposited on the light-emitting unit  200  in a process in which the light-emitting device chip  100  is formed before performing a wire-bonding process, a complicated process for exposing the bonding pad for a wire-bonding process in the light-emitting unit  20  is required. 
     In the light-emitting device package  2  according to the present invention, the light-emitting device  1 , in which the phosphor layer  200  is formed on the phosphor layer  200  of the substrate  10  or on the side surfaces  12  and the bottom surface  13  of the substrate  10 , is mounted on the package body  300 , and the second phosphor layer  210  is formed after performing the wire-bonding process, and thus the phosphor layer  200  having a uniform quality may be formed on upper, lower, and side surfaces of the light-emitting device chip  100 . Accordingly, light emitted from the light-emitting device chip  100  may be changed to light having a uniform chromaticity. 
     Also, the method of forming the phosphor layer  200  and the second phosphor layer  210  by using the CLD method may be limited to a case where a thin GaN-type substrate is used. However, because it is difficult to form a phosphor layer on side surfaces of a substrate, it is difficult to use the CLD method when a relatively low-priced sapphire substrate is used. However, according to the light-emitting device, the method of manufacturing the light-emitting device, and the light-emitting device package according to the present invention, even when a relatively thick sapphire substrate is used, a phosphor layer may be uniformly formed even on side surfaces of the sapphire substrate. Accordingly, a light-emitting device and a light-emitting device package having a high chromaticity may be realized. 
     In the above-described embodiment, a case where the light-emitting device  1  is packaged by using a pre-mold method has been described, but the scope of the present invention is not limited thereto. For example, the light-emitting device  1  may be packaged by using a wire-bonding method. Referring to  FIG. 6 , a package body of a wire-bonding type light-emitting device package  2   a  includes a circuit substrate  90 . The wire-bonding type light-emitting device package  2   a  may be formed by mounting the light-emitting device  1 , in which the phosphor layer  200  is formed on the side surfaces  12  or on the side surfaces  12  and the bottom surface  13 , on the circuit substrate  90 , electrically connecting the light-emitting unit  20  and electrical terminal units  91  and  92  disposed on the circuit substrate  90  respectively by the wires  331  and  332 , and depositing a fluorescent material-containing resin on the light-emitting unit  20 . In this case, a plurality of the light-emitting devices  1  may be formed on the circuit substrate  90  through wire-bonding. 
     Also, the light-emitting device  1  may be packaged through flip-chip-bonding. Referring to  FIG. 7 , a package body of a light-emitting device package  2   b  includes the circuit substrate  90 . The light-emitting device  1  is formed on the circuit substrate  90  through flip-chip-bonding so that the light-emitting unit  20  faces downward, and thus the light-emitting unit  20  may be electrically connected to the electrical terminal units  91  and  92  formed on the circuit substrate  90 . In this case, since light exits from the bottom surface  13  and the side surfaces  12  of the substrate  10 , the light-emitting device  1  in which the phosphor layer  200  is formed on the bottom surface  13  and the side surfaces  12  of the substrate  10  may be preferably employed. After the flip-chip-bonding process is performed, a fluorescent material-containing resin may be deposited between the light-emitting unit  20  and the circuit substrate  90  so as to form the second phosphor layer  210 . A plurality of the light-emitting devices  1  may be formed on the circuit substrate  90  through flip-chip-bonding. 
     It should be understood that the exemplary embodiments described therein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments.