PATENT DOCUMENT

Publication Number: US-9643272-B2
Application Number: US-201414460296-A
Country: US
Kind Code: B2

Title: Encapsulation process enabling hotbar soldering without direct PCB support

Abstract:
A method for connecting or terminating wires to a printed circuit is disclosed. The method includes applying layers, such as a first layer and a second layer, to the printed circuit. The first layer is applied over several active components on the printed circuit, and provides a sealant against ingress of contaminants in the active components. The second layer is a rigid layer applied over the first layer. When the printed circuit is placed in a fixture, a metallic element, such as a thermode or hot bar, presses against the wires to hold the wires against several terminals on the printed circuit. The metallic element is heated to melt solder between the wires and the terminals. The second layer is configured to resist compressive forces from the metallic element and the fixture, such that the printed circuit and the active components are not damaged during the connection process.

Claims:
What is claimed is: 
     
       1. A method for forming a connector having a circuit board having a first surface comprising an electrical component and a second surface comprising a terminal configured to couple with a wire, wherein the second surface is opposite the first surface, the electrical component is located at a first location of the first surface, and the terminal is located at a second location of the second surface directly opposite the first surface, the method comprising:
 applying a first moisture sealant layer to the first surface to cover the electrical component without covering the terminal on the second surface, the first layer made from a first material and having a nonlinear outer surface; and 
 applying a second layer over the first layer to form a planar outer surface parallel to the second surface without covering the terminal on the second surface, the second layer made from a second material different from and more rigid than the first material; and 
 thereafter, soldering a wire to the terminal, wherein the first layer and the second layer only cover the second surface. 
 
     
     
       2. The method as recited in  claim 1 , wherein the electrical component is located at a first location of the first surface, and wherein the terminal is located at a second location of the second surface, the second location corresponding to the first location such that the second location is opposite the first location. 
     
     
       3. The method as recited in  claim 1 , further comprising forming a housing around the circuit board such that the housing 1) covers the first layer and the second layer, and 2) allows a portion of the circuit board to extend from the housing. 
     
     
       4. The method as recited in  claim 1 , further comprising:
 forming a first structural component coupled with the circuit board at a first end; and 
 forming a second structural component coupled with the circuit board at a second end opposite the first end, wherein the first layer and the second layer are disposed between the first structural component and the second structural component. 
 
     
     
       5. A connector for use with a cable assembly having a wire, the connector at an intermediate stage of manufacture comprising:
 a substrate having a first surface and a second surface opposite the first surface; 
 a terminal electrically coupled with the substrate and exposed at the first surface to enable the wire to be soldered to the terminal; 
 an electrical component positioned on the second surface at a location directly opposite the terminal; 
 a first layer covering the electrical component and providing a seal against moisture ingress, the first layer conforming to a topography of the electrical component to form a non-linear outer surface; and 
 a second layer formed directly on the outer surface of the first layer and covering the first layer to form a planar outer surface over and parallel to the substrate second surface, the second layer comprising a rigid material. 
 
     
     
       6. The connector as recited in  claim 5 , wherein the substrate includes a first dimension, a second dimension, and a third dimension, the first dimension is approximately 10 millimeters, the second dimension is less than the first dimension, and the third dimension is less than the first dimension. 
     
     
       7. The connector as recited in  claim 5 , wherein the substrate comprises a printed circuit board. 
     
     
       8. The connector as recited in  claim 7 , wherein the electrical component comprises at least an integrated circuit, an analog circuit, or an authentication circuit. 
     
     
       9. The connector as recited in  claim 5 , wherein the first layer comprises acrylic and the second layer comprises polyurethane or polyamides. 
     
     
       10. The connector as recited in  claim 5 , wherein the first layer and the second layer combine to define a protective cover for an assembly operation to electrically and mechanically couple the wire with the terminal. 
     
     
       11. The connector as recited in  claim 5 , further comprising a housing that covers the terminal, the electrical component, the first layer, and the second layer. 
     
     
       12. The connector as recited in  claim 11 , further comprising a sheath member that covers the wire. 
     
     
       13. The connector as recited in  claim 12 , further comprising a shroud member may that supports the housing in a location where the sheath member engages the housing. 
     
     
       14. The connector as recited in  claim 5 , wherein the first layer and the second layer comprise only an electrically inert material. 
     
     
       15. A connector for a cable assembly, the connector at an intermediate stage of manufacture comprising:
 a circuit board comprising an electrical component and a pin on a first surface, and a terminal exposed at a second surface opposite the first surface; 
 a wire electrically coupled with the circuit board at the terminal, wherein the pin is used by the wire to electrically couple the cable assembly with an electronic device; and 
 a first protective coating covering the electrical component and providing a seal against moisture ingress, the first layer conforming to a topography of the electrical component to form a non-linear outer surface; and 
 a second protective coating formed directly on the non-linear outer surface of the first layer and covering the first layer to form a planar outer surface over and parallel to the substrate first surface. 
 
     
     
       16. The connector as recited in  claim 15 , wherein the first protective coating comprises a potting material covering the electrical component to prevent liquid ingress to the electrical component; and the second protective coating comprises a rigid layer covering the potting material and the electrical component. 
     
     
       17. The connector as recited in  claim 15 , wherein the terminal on the second surface is directly opposite the electrical component on the first surface. 
     
     
       18. The connector as recited in  claim 15 , wherein the first and second protective coatings are disposed only on the first surface such that the terminal and wire remain uncovered by the protective coatings. 
     
     
       19. The connector as recited in  claim 18 , further comprising:
 a first structural component coupled with the circuit board at a first end; and 
 a second structural component coupled with the circuit board at a second end opposite the first end, wherein the first protective coating is disposed between the first structural component and the second structural component. 
 
     
     
       20. The connector as recited in  claim 15 , further comprising a housing positioned on the circuit board such that the housing covers the first protective coating, and allows a portion of the circuit board having the pin to extend from the housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of International Application No. PCT/US14/51122, with an international filing date of Aug. 14, 2014, entitled “ENCAPSULATION PROCESS ENABLING HOTBAR SOLDERING WITHOUT DIRECT PCB SUPPORT”, which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The described embodiments relate generally to soldering. In particular, the present embodiments relate to applying at least one protective layer over components in a device such that localized soldering may be performed without damaging the components and/or a substrate that receives the components. 
     BACKGROUND 
     Wire terminations and subsequent connections to a substrate (e.g., PCB) via soldering are generally known in the art. One method of soldering includes using a thermode, or “hot bar,” that engages a wire to be connected to a substrate via solder. The hot bar is heated to a temperature which causes solder to melt or flow between or around the wire and substrate. Once the hot bar is either removed from the wire or cooled below the melting point of the solder, the solder forms an electrical and mechanical bond between the wire and the substrate. This method may be useful on large substrates performed in locations free of sensitive components. 
     However, the hot bar method of soldering is ineffective in instances where relatively small substrates are used. In order to hold a wire to be soldered on the substrate, the hot bar applies a force against the wire; at least some of the force is applied to the substrate, causing the substrate to warp. As a result, the substrate may become non-compliant with a structure (e.g., housing) that receives the substrate. Further, the force acting on the substrate may cause permanent damage to the substrate. 
     The force applied to the substrate can cause additional issues. For example, any components proximate to a surface of the substrate, including on a surface opposite the surface to be soldered, may be damaged. In addition to the force applied, liquid or chemicals (e.g., flux) used in the soldering process may engage the components and cause damage to the components. Accordingly, either the components, such as advanced components providing improved capabilities, may not be used with the cable assembly resulting in an inferior device, or the structure which houses the substrate cannot reduce its footprint resulting in an unnecessarily large structure. 
     SUMMARY 
     In one aspect, a method for connecting a wire to a printed circuit board (PCB) is described. The method may include applying a first layer to a first portion of the PCB. In some embodiments, the first layer is made from a first material and covers a component that is electrically connected to the PCB. The method may further include applying a second layer over the first layer. The second layer made from a second material different than the first material. Also, the second layer may be formed over the first layer such that the second layer includes a substantially level surface. The method may further include clamping, with a metallic element, the wire against a terminal on a second portion of the PCB. The second portion of the PCB may be directly opposite the first portion. The method may further include heating the metallic element to melt a solder element positioned between the wire and the terminal. 
     In another aspect, a connector is described. The connector may include a substrate having a first portion and a second portion opposite the first portion. The connector may further include several terminals positioned on the first portion; the several terminals may include a first terminal. The connector may further include several components positioned on the second portion; the several components may include a first component directly opposite the first terminal. The connector may further include a first layer covering the several components. In some cases, the first layer is configured to protect the several components from ingress of moisture. The connector may further include a second layer covering the first layer. In some embodiments, an outer peripheral portion of the second layer includes a substantially level surface. Also, in some embodiments, the second layer is free of compression during an assembly process of the connector. 
     In another aspect, a method for terminating a plurality of wires of a connector to a substrate is described. The method may include applying a first layer over a first portion of the substrate positioned within a housing of the connector. In some cases, the first layer may cover a plurality of components electronically connected to the substrate. The method may further include applying a second layer over the first layer. The second layer may be cured to form a substantially level surface. The method may further include placing the second layer against a fixture. The method may further include engaging the plurality of wires with a metallic element to hold the plurality of wires against a plurality of terminals positioned on a second portion of the substrate. The second portion is directly opposite the first portion. The plurality of wires may include a first wire and the plurality of terminals may include a first terminal. The method may further include melting a metallic material to bond the first wire to the first terminal In some cases, melting the metallic material includes heating the metallic element. Also, the second layer is free of compression between the metallic element and the fixture. 
     In another aspect, a machine-readable non-transitory storage medium storing instructions that, when executed by a processor included in a computing device, cause the computing device to carry out several steps. One step may include applying a first layer to a first portion of the printed circuit board (PCB). The first layer may be made from a first material. In some cases, the first layer covers a component electrically connected to the PCB. Another step may include applying a second layer over the first layer. The second layer may be made from a second material different than the first material. Also, the second layer may be formed over the first layer such that the second layer includes a substantially level surface. Another step may include clamping the wire against a terminal positioned on a second portion of the PCB with a metallic element. The second portion is opposite the first portion. Another step may include heating the metallic element to melt a solder element positioned between the wire and the terminal. In some cases, the metallic element holds the wire against the second side with a force. Also, in some cases, the second layer is free of compression between the metallic element and the fixture. 
     Other systems, methods, features and advantages of the embodiments will be, or will become, apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description and this summary, be within the scope of the embodiments, and be protected by the following claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1  illustrates an embodiment of a cable assembly; 
         FIG. 2  illustrates the embodiment of the cable assembly shown in  FIG. 1 , with the housing, the sheath member and the shroud member removed to show internal features of the cable assembly;  FIG. 2  further shows a bottom view of the cable assembly and a substrate positioned within a portion of a connector; 
         FIG. 3  illustrates the embodiment of the cable assembly shown in  FIG. 2 , rotated 180 degrees about a longitudinal axis to show a top view (opposite the bottom view); 
         FIG. 4  illustrates an isometric view of the embodiment of the cable assembly shown in  FIG. 2 , further showing several components on a first portion of the substrate; 
         FIG. 5  illustrates an isometric view of a cable assembly having a first layer applied over several components positioned on a first portion of a substrate; 
         FIG. 6  illustrates a cross sectional view of the cable assembly taken along the two-dimensional feature shown as Section A in  FIG. 5 , showing the first layer applied over several components, in accordance with the described embodiments; 
         FIG. 7  shows an isometric view of an embodiment of a cable assembly having a second layer applied over a first layer; 
         FIG. 8  illustrates a cross sectional view of the cable assembly taken along the two-dimensional feature shown as Section B in  FIG. 7 , showing a second layer applied over a first layer, in accordance with the described embodiments; 
         FIG. 9  illustrates an isometric view of an assembly process of the cable assembly having a first layer and a second layer; 
         FIG. 10  illustrates a cross sectional view of the cable assembly taken along the two-dimensional feature shown as Section C in  FIG. 9 , showing a first wire held between a metallic element and a solder element in order to solder the first wire to a first terminal; 
         FIG. 11  illustrates an isometric view of an enlarged portion of an electronic device undergoing an assembly process including a portion of a flexible circuit electro-mechanically connected to a substrate, in accordance with the described embodiments; 
         FIG. 12  illustrates a block diagram of a computing device that can represent the components of the various embodiments discussed herein; 
         FIG. 13  illustrates a flowchart showing a method for connecting a wire to a printed circuit board (PCB); and 
         FIG. 14  illustrates a flowchart showing a method for terminating several wires of a connector to a substrate. 
     
    
    
     Those skilled in the art will appreciate and understand that, according to common practice, various features of the drawings discussed below are not necessarily drawn to scale, and that dimensions of various features and elements of the drawings may be expanded or reduced to more clearly illustrate the embodiments of the present invention described herein. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     In the following detailed description, references are made to the accompanying drawings, which form a part of the description and in which are shown, by way of illustration, specific embodiments in accordance with the described embodiments. Although these embodiments are described in sufficient detail to enable one skilled in the art to practice the described embodiments, it is understood that these examples are not limiting such that other embodiments may be used, and changes may be made without departing from the spirit and scope of the described embodiments. 
     The following disclosure relates to a process for terminating (or connecting) wires to a substrate, which may include soldering the wires to a printed circuit board (“PCB”) having terminals which receive the wires. In some cases, the wires are part of a cable assembly having a substrate positioned within a housing of the cable assembly. The substrate may include a surface having several components electrically connected to the substrate. One of the components may be, for example, an authentication chip on an integrated circuit (“IC”) for authenticating a pair of electronic devices, both of which are electrically connected to the cable assembly. Alternatively, one of the components may be an analog circuit, or a battery monitor IC that monitors the battery power of an electronic device connected to the cable assembly. 
     Despite the functionality of the substrate, the surface of the substrate that receives these components may nonetheless include a relatively small surface area in order fit within a housing of the cable assembly. In some cases, the surface area is less than 0.5 square centimeters (“cm 2 ”), and in some cases, approximately 0.25 cm 2  or less. Further, the thickness of the substrate be approximately 1-2 millimeters (“mm”) or less. Also, some components may be fragile and susceptible to damage during an assembly process, that is, when wires are electro-mechanically connected to the substrate. To terminate the wires on the terminals of the relatively small substrate without damaging the substrate and the components on the substrate, one or more layers of material may be applied to the substrate, and in particular, applied to the components. For example, a first layer may be configured to prevent ingress of contaminants, such as liquids or other forms of moisture. In some cases, a second layer may be applied over the first layer. The second layer may be formed from rigid material, or materials, and provide a flat or level surface to facility the assembly process. 
     To solder the wires to the substrate, the substrate may be placed within a fixture, with the level surface of the second layer engaged with the fixture. The wires may be positioned on terminals located on a surface directly opposite the surface having the components and the layers. A metallic element may be configured to hold the wires against the terminals. The metallic element may also be heated to a temperature capable of melting a solder element located on the wires and/or terminals. The metallic element may impose a force on the wires and the substrate which may be transferred to the first and second layers on the opposite surface. In addition, the fixture may impose an opposing, resistive force in the opposite direction. However, the second layer is formed from rigid materials sufficient to resist both forces thereby allowing the soldering process on the small substrate without damaging the substrate or the components. 
     These and other embodiments are discussed below with reference to  FIGS. 1-14 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  illustrates an embodiment of cable assembly  100 . Cable assembly  100  may include sheath member  102  extending from shroud member  104 . Sheath member  102  may include several wires (not shown) extending through sheath member  102  that may terminate to a connector (not shown). Sheath member  102  may be made from an electrically insulating material, such as a polymeric material, designed to bend or flex. Shroud member  104  may offer additional rigidity and support in a location where sheath member  102  engages housing  106 . Housing  106  provides a cover for internal components (e.g., PCB, IC, etc.). Cable assembly  100  may also include connector  108  configured to engage an electronic device. Connector  108  may include several pins  110  configured to electrically connect cable assembly  100  to an electronic device, such as a portable electronic device (e.g., smartphone) or a tablet computing device. For example, first pin  112  may provide a pathway for electric current to enter the electronic device for purposes of charging, while second pin  114  may be configured to transmit data to and from the electronic device. 
       FIGS. 2 and 3  illustrate the embodiment of cable assembly  100  shown in  FIG. 1 , with the housing, the sheath member and the shroud member removed to show internal features of cable assembly  100 .  FIG. 2  illustrates a bottom view of cable assembly  100  showing substrate  122  positioned within a portion of connector  108 . In some embodiments, substrate  122  is made from PCB configured to electrically connect several ICs and other discrete components to each other as well as other external devices. Substrate  122  may include first portion  124  having several components  130  positioned on first portion  124 . For example, first portion  124  may include first component  132  and second component  134 . First component  132  and/or second component  134  may be selected from, but not limited to, an IC configured to allow electronic devices to perform a “handshake,” digital logic block, an analog circuit, or a series of ICs configured to perform several operations (e.g., send or receive a signal) over a relatively few number of pins, such as second pin  114 . While the embodiment shown in  FIG. 2  shows seven components, in some embodiments, first portion  124  of substrate  122  includes eight or more components. Alternatively, in other embodiments, first portion  124  of substrate  122  includes one to six components. Also, substrate  122  includes contacts  136  corresponding to pins  110 . Contacts  136  provide an electrical contact from substrate  122  to pins  110 . 
       FIG. 3  illustrates the embodiment of cable assembly  100  shown in  FIG. 2 , rotated  180  degrees about a longitudinal axis  140  show a top view (opposite the bottom view). Substrate  122  may include second portion  144  directly opposite first portion  124  (shown in  FIG. 2 ). Second portion  144  may include terminals  150  that provide a termination point for wires (not shown) of cable assembly  100 , and further electrically connect the wires to substrate  122 . Terminals  150  may be located on second portion  144  in a location directly opposite components  130  (shown in  FIG. 2 ) on first portion  124 . Terminals  150  may be formed from electrically conductive materials (e.g., metal, brass, gold, etc.). In the embodiment shown in  FIG. 3 , terminals  150  include four terminals, including first terminal  152 , second terminal  154 , third terminal  156 , and fourth terminal  158 . However, in other embodiments, terminals  150  could include one to three terminals. Still, in other embodiments, terminals  150  could include five or more terminals. Generally, the number of terminals corresponds to the number of wires needed for cable assembly  100 . 
       FIG. 3  further shows the dimensions of connector  108  and substrate  122 . For example, substrate  122  includes length 160 approximately in the range of 7 to 13 mm. Also, a portion of connector  108  visible when the housing is not removed includes length  162  and width  164 , both of which are approximately in the range of 4 to 6 mm. It will be appreciated that the width of substrate  122  is less than the width of connector  108 . 
       FIG. 4  illustrates an isometric view of the embodiment of cable assembly  100  shown in  FIG. 2 , further showing components  130  on first portion  124  of substrate  122 . Also, substrate  122  includes thickness  166  approximately in the range of 0.5 to 1 mm. As a result these relatively small dimensions, assembly processes performed on substrate  122 , such as connecting wires to terminals  150  (shown in  FIG. 3 ) may cause a force on substrate  122  sufficient to damage or break substrate  122 . In some cases, the force on substrate  122  may cause substrate  122  to warp, in which case substrate  122  may no longer be compliant with a housing (e.g., housing  106 ). Also, in cases where substrate  122  includes components  130  that are fragile, forces imposed by assembly processes performed on the second portion of substrate  122  may be transferred to components  130  thereby causing damage to components  130 , resulting in a non-functioning cable assembly. 
     In this regard, a protective element may be applied to components in order to withstand at least some forces associated with an assembly process. For example,  FIGS. 5 and 6  illustrate an embodiment of cable assembly  100  having several components  130  on first portion  124  of substrate  122 .  FIG. 5  illustrates an isometric view of cable assembly  100  having first layer applied over components  130  and first portion  124 . First layer  170  is configured to form a sealant against ingress from liquid or moisture in order to prevent damage to substrate  122  and components. First layer  170  may provide some resistance to forces associated with assembly processes of cable assembly  100 . In some embodiments, first layer  170  is formed from acrylic. In some embodiments, first layer  170  includes acrylate. Further, in some embodiments, first layer  170  is formed from LOCTITE® Eccobond UV9060F UV encapsulant from Henkel Corp., of Düsseldorf, Germany. In other embodiments, first layer  170  is made from Hysol UV9060F from Henkel Corp., of Düsseldorf, Germany. Generally, first layer  170  may be made from any material or materials known in the art for potting a circuit board enclosed in a housing. Also, first layer  170  may be applied to first portion  124  by several methods. For example, a print head from printing machine, including a three-dimensional printer, may be configured to release first layer  170  over first portion  124 . Alternatively, first layer  170  may be molded over components  130  by a mold member (not shown) used as part of an injection molding process. 
     First layer  170  may be cured by UV and/or visible light. However, during the curing process, first layer  170  may form a non-linear surface. For example,  FIG. 6  shows a cross sectional view of cable assembly  100  taken along the two-dimensional feature shown as Section A in  FIG. 5 , showing first layer  170  applied over components  130 . First layer  170  also includes non-linear portion  172 . Non-linear portion  172  may be any non-flat surface formed from the curing process. While first layer  170  may be sufficient to provide protection to substrate  122  and/or components  130  during an assembly process, non-linear portion  172  may be undesirable in some instances. For example, in order to connect wires to substrate  122  via terminals  150 , cable assembly  100  may be positioned within a fixture having a flat surface. However, if cable assembly  100  is placed on the fixture with non-linear portion  172  engaging the fixture, cable assembly  100  will not lie flat or level. Accordingly, in some cases, the machinery may need additional adjustments to compensate. 
     However, in some embodiments, an additional layer may be applied to first layer  170  in order to form a flat or level surface.  FIGS. 7 and 8  illustrate an embodiment of cable assembly  100  having second layer  180  applied over first layer  170 .  FIG. 7  shows an isometric view of cable assembly  100  having second layer  180  applied over first layer  170 . Second layer  180  may be formed from materials such as ethylene vinyl acetate (“EVA”) polyurethane, polyamides, metallocene polyalphaolefins, or a combination thereof. Further, in some embodiments, second layer  180  is formed from Macromelt® from Henkel Corp., of Düsseldorf, Germany. In other embodiments, second layer  180  is made from Technomelt, including Technomelt Supra™ or Technomelt Extra™, from Henkel Corp., of Düsseldorf, Germany Generally, second layer  180  is made from rigid materials, including adhesives, such that second layer  180  is not compressed during assembly processes of cable assembly  100 . In other words, second layer  180  can resist deformation which provides a dimension of protection to substrate  122  and components  130 . In addition, second layer  180  is capable curing at relatively low temperatures (e.g., 200 degrees Celsius or less) and low pressure. In this manner, second layer  180  will not be heated sufficiently as to allow certain metals, such as solder, to melt or reflow. Also, second layer  180  may be applied to substrate  122  in any manner previously described for first layer  170 . 
       FIG. 8  illustrates a cross sectional view of cable assembly  100  taken along the two-dimensional feature shown as Section B in  FIG. 7 , showing second layer  180  applied over first layer  170 . When second layer  180  is cured, second layer  180  may include linear portion  182  which is generally flat or level, regardless of the dimensions of non-linear portion  172 . In this manner, cable assembly  100  may be placed in the fixture previously described, with linear portion  182  providing a level or flat surface to facilitate the assembly process. Also, second layer  180  includes thickness  184  that remains constant during the assembly process of cable assembly  100  (discussed below). 
       FIG. 9  illustrates an isometric view of an assembly process of cable assembly  100  having first layer  170  and second layer  180  (shown in  FIGS. 7 and 8 ). Cable assembly  100  may be positioned in fixture  202  to facilitate the assembly process. The assembly process may include connecting several wires  210  to substrate  122  via metallic element  220  and solder (not shown). The assembly process may include metallic element  220 , which, as shown, is capable of engaging and holding, or clamping, in place first wire  212 , second wire  214 , third wire  216 , and fourth wire  218  against first terminal  152 , second terminal  154 , third terminal  156 , and fourth terminal  158 , respectively (terminals are shown in  FIG. 3 ). Generally, metallic element  220  is made of metal or a metal alloy capable of heat transfer. In some embodiments, metallic element  220  is a thermode, or hot bar, that is part of a tool which heats metallic element  220  to a temperature which melts the solder thereby electrically and mechanically connecting wires  210  to substrate  122  via terminals  150 . Heating means may include applying electrical current through metallic element  220  to produce electrical resistance thereby generating heat. Further, heat may be removed from metallic element  220  to solidify the solder. Alternatively, metallic element  220  may be cooled to facilitate solidifying the solder. 
       FIG. 10  illustrates a cross sectional view of cable assembly  100  taken along the two-dimensional feature shown as Section C in  FIG. 9 , showing an exemplary first wire  212  held between metallic element  220  and solder element  222  in order to solder first wire  212  to first terminal  152 . It will be appreciated that the remaining wires and terminals include a similar configuration (i.e., wires are between metallic element  220  and respective solder elements). In this configuration, metallic element  220  may apply a first force  232  to first wire  212  in order to maintain first wire  212  in place. First force  232  is designated as an arrow pointing to a direction toward first portion  124  of substrate  122 . However, in order to offset, or counteract, first force  232  and the force (weight) of cable assembly  100 , fixture  202  may apply a second force  234  designated as an arrow pointing in a direction toward second portion  144  of substrate  122 . Generally, first force  232  and second force  234  are opposing forces. As a result, substrate  122  may undergo additional stress. However, second layer  180  is configured to resist first force  232  and second force  234 . In other words, second layer  180  does not compress during the described assembly process, as second layer  180  retains the same thickness  184  prior to the assembly process. Accordingly, substrate  122  and first component  132  are not damaged during the assembly process, despite their relatively small dimensions. 
     In some embodiments, cable assembly  100  may include only second layer  180 , that is, the materials described to form second layer  180 . In other words, in some embodiments, first layer  170  is not applied to cable assembly  100 . 
     While the described embodiments include methods for connecting wires to a connector to form a cable assembly, this process may be applied to other electronic devices. For example,  FIG. 11  illustrates an isometric view of an enlarged portion of electronic device  300  undergoing an assembly process including a portion of flexible circuit  302  electro-mechanically connected to substrate  304 . Electronic device  300  may be selected from a portable electronic device, a desktop computing device, or a tablet computing device. In some embodiments, flexible circuit  302  is configured to carry an electrical signal to and from components within, for example, a keyboard or a display panel, of electronic device  300 . Also, in some embodiments, substrate  304  is a PCB. Flexible circuit  302  may include a bottom portion having a solder engaged with a first portion  306  of substrate  304 . The assembly process may further include metallic element  320 . Metallic element  320  may be part of a tool which heats metallic element  320  to a temperature which melts the solder thereby electrically and mechanically connecting flexible circuit  302  to substrate  304 . 
     Substrate  304  may include several components  310  on a second portion opposite first portion  306 . Components  310  may include any components previously described for components  130 . Accordingly, components  310  may be fragile and susceptible to damage during the assembly process. Also, substrate  304  may include thickness  312  approximately in the range 0.5 to 2 mm, which may be insufficient to withstand a force generated by metallic element  320  on flexible circuit  302  and substrate  304 . In other words, substrate  304  may become warped or damaged during the assembly process without further reinforcement. 
     In order to withstand damage during assembly, the second portion of substrate  302  may be coated with first layer  322  and second layer  324 . First layer  322  may include any material or combination of materials previously described for first layer  170  (shown, for example, in  FIGS. 5 and 6 ). Also, second layer  324  may include any material or combination of materials previously described for second layer  180  (shown, for example, in  FIGS. 7 and 8 ). Accordingly, at least second layer  324  may be sufficiently rigid to withstand first force  332  generated by metallic element  230  as well as an opposing second force  334  generated by fixture  340  in order to offset first force  332  and the force (weight) of cable assembly  300 . As such, second layer  324  maintains thickness  236  throughout the assembly process, and neither substrate  302  nor components  310  are damaged. 
       FIG. 12  illustrates a block diagram of computing device  400  that can represent the components of the various embodiments discussed herein. It will be appreciated that the components, devices or elements illustrated in and described with respect to  FIG. 12  may not be mandatory and thus some may be omitted in certain embodiments. Computing device  400  can include processor  402  that represents a microprocessor, a coprocessor, circuitry and/or a controller for controlling the overall operation of computing device  400 . Although illustrated as a single processor, it can be appreciated that the processor  400  can include a plurality of processors. The plurality of processors can be in operative communication with each other and can be collectively configured to perform one or more functionalities of the computing device  400  as described herein. In some embodiments, processor  402  can be configured to execute instructions that can be stored at the computing device  400  and/or that can be otherwise accessible to the processor  402 . As such, whether configured by hardware or by a combination of hardware and software, the processor  402  can be capable of performing operations and actions in accordance with embodiments described herein. 
     Computing device  400  can also include user input device  404  that allows a user of the computing device  400  to interact with the computing device  400 . For example, user input device  402  can take a variety of forms, such as a button, keypad, dial, touch screen, audio input interface, visual/image capture input interface, input in the form of sensor data, etc. Still further, computing device  400  can include display  408  (e.g., screen display) that can be controlled by processor  402  to display information to a user. Controller  410  can be used to interface with and control different equipment through equipment control bus  412 . Computing device  400  can also include network/bus interface  414  that couples to data link  416 . Data link  416  can allow computing device  400  to couple to a host computer or to accessory devices. Data link  416  can be provided over a wired connection or a wireless connection. In the case of a wireless connection, network/bus interface  414  can include a wireless transceiver. 
     Computer device  400  can also include storage device  418 , which can have a single disk or several disks (e.g., hard drives) and a storage management module that manages one or more partitions (also referred to herein as “logical volumes”) within storage device  418 . In some embodiments, storage device  418  can include flash memory, semiconductor (solid state) memory or the like. Still further, computing device  400  can include Read-Only Memory (“ROM”)  422  and Random Access Memory (“RAM”)  424 . ROM  422  can store programs, code, instructions, utilities or processes to be executed in a non-volatile manner. RAM  424  can provide volatile data storage, and stores instructions related to components of the storage management module that are configured to carry out the various techniques described herein. The computing device can further include data bus  426 . Data bus  426  can facilitate data and signal transfer between at least processor  402 , controller  410 , network interface  414 , storage device  418 , ROM  422 , and RAM  424 . 
       FIG. 13  illustrates a flowchart  500  showing a method for connecting a wire to a printed circuit board (PCB). In step  502 , a first layer is applied to a first portion of the PCB. In some embodiments, the PCB includes a component electrically connected to the PCB. In some embodiments, the first layer includes a UV encapsulant that protects a component from ingress of liquids or moisture. In step  504 , a second layer is applied over the first layer. In some embodiments, the second layer is made from a rigid material configured to resist compression during an assembly process. Also, in some embodiments, the second layer may be cured to include a substantially flat or level surface regardless of whether the first layer on which second layer is applied includes any non-linear surface. In step  506 , the wire is held in place with a metallic element against a terminal located on a second portion of the PCB. The second portion is opposite the first portion. In step  508 , the metallic element is heated to melt a solder element positioned between the wire and the terminal. 
     In some cases, the metallic element may hold the wire in place with a force. Also, the fixture may impose a second force in the opposite direction as the force imposed by the metallic element. However, the second layer is does not compress despite the two forces acting upon the second layer. In this manner, the PCB and the component are not damaged the connection (or assembly) process. 
       FIG. 14  illustrates a flowchart  600  showing a method for terminating several wires of a connector to a substrate. In step  602 , a first layer is applied to a first portion of the substrate. The substrate is positioned within a housing of the connector. In some embodiments, the first layer covers several components which are electrically connected to the substrate. The components may be selected from, for example, an integrated circuit, a processor, and/or an analog circuit. In step  604 , a second layer is applied over the first layer. In some embodiments, when the second layer is cured, the second layer forms a substantially level surface over the first layer. In step  606 , the second layer is placed against a fixture. The fixture may be configured to hold a portion of the connector during an assembly process which includes connecting wires to the substrate. In step  608 , a metallic element engages the several wires to hold the wires in against several terminals which are positioned on a second portion of the substrate. In some embodiments, the second portion is directly opposite the first portion. Also, in some embodiments, the several wires include a first wire and the several terminals include a first terminal. In step  610 , the metallic element is heated to melt a metallic material such that the first wire is bonded to the first terminal. The bond includes an electrical and a mechanical bond. Also, in some embodiments, the metallic material is solder. Also, the metallic element and the fixture may impose forces on the substrate, the first layer, and the second layer. However, the second layer is capable of resisting the opposing forces and does not compress during the assembly process. 
     The various aspects, embodiments, implementations or features of the described embodiments can be used separately or in any combination. Various aspects of the described embodiments can be implemented by software, hardware or a combination of hardware and software. The described embodiments can also be embodied as computer readable code on a computer readable medium for controlling manufacturing operations or as computer readable code on a computer readable medium for controlling a manufacturing line. The computer readable medium is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include read-only memory, random-access memory, CD-ROMs, HDDs, DVDs, magnetic tape, and optical data storage devices. The computer readable medium can also be distributed over network-coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. 
     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 targeted 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: 20140814
Publication Date: 20170509
Grant Date: 20170509
Priority Date: 20140814
Inventors: TANG CHIU-YU
KAMEI IBUKI
RASMUSSEN TIMOTHY J.
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K3/284", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2203/304", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/3494", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K3/0471", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2203/1322", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10287", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10287", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K1/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K3/3494", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/284", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K1/0016", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K3/34", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2203/304", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K1/0016", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2203/1322", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K3/0471", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/34", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/284", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K3/0471", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2203/1322", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/34", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/3494", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K1/0016", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2203/304", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K1/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K2201/10287", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 55303214