Patent Publication Number: US-2023156953-A1

Title: Managing unwanted heat, mechanical stresses and emi in electrical connectors and printed circuit boards

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Patent Application No. 63/006,960 filed on Apr. 8, 2020; U.S. Patent Application No. 63/007,168 filed on Apr. 8, 2020; U.S. Patent Application No. 63/008,311 filed on Apr. 10, 2020; U.S. Patent Application No. 63/019,092 filed on May 1, 2020; and U.S. Patent Application No. 63/198,332 filed on Oct. 12, 2020. The entire contents of each application are hereby incorporated by reference. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates to improving unwanted mechanical, thermal, and electro-magnetic interference (EMI) issues in electronic systems. Mechanically, both toolless, slide-on substrate stiffeners surface-mount technology (SMT) electronic-component hold downs with pre-attached or pre-formed solder units are provided. Thermally, heat-dissipation material, such as graphene or nanomaterial, can be added to electrically conductive or electrically non-conductive electrical interconnect portions. Clips with two or more points of physical or electrical contact can be attached to power-conductor mating ends with only one point of physical contact, helping to reduce contact resistance. Removal or reduction of unwanted EMI from an inductor is also disclosed. 
     2. Description of Other Technical Approaches 
     Mechanical Stress Management 
     Printed circuit or printed wiring boards (collectively referred to as PCBs) can have unwanted bowing, causing a loss of coplanarity. Bowing can be caused by heat-driven expansion, coefficient of thermal expansion (CTE) mismatches, forces from electrical component fasteners, manufacturing tolerance stack-ups, etc. Board stiffeners are sometimes used to reinforce a PCB and help to maintain planarity of a surface of a PCB. 
     An electrical component attached to a substrate by SMT can also experience unwanted mechanical stresses, particularly at the solder connection between the electrical component and the PCB. Unwanted stress cracks can appear in reflowed fusible elements, for example, spherical solder balls that are reflowed onto a substrate or to corresponding pads carried by a substrate. This can cause electrical opens, which are also undesirable. To help mitigate these mechanical stresses, electrical connector through hole or wave solder hold downs/board locks can be SMT mounted to the substrate. The solder balls can also form a cross-sectional hourglass shape, after reflow, to help counteract unwanted mechanical stresses. 
     Heat Management 
     Unwanted heat can cause mechanical stress from a coefficient of thermal expansion (CTE) mismatch between an electrical component and a substrate to which the electrical component is attached. Unwanted heat can also cause electrical components to fail or can cause the working life of the electrical components to be shortened. 
     Electrical components that receive or carry current, including, for example, electrical power conductors, mateable electrical connectors, VCELs, optical engines, and transceivers, can produce unwanted heating, including Joule heating, resistive heating, resistance heating, and Ohmic heating. Joule&#39;s first law is expressed as H/t=I 2 R, where H is heat in Joules (J); t is elapsed time in seconds (s); I is current in amperes (A); and R is electrical resistance in ohms (Ω). The higher the current and the resistance, the more unwanted heat that is generated. 
     Mateable electrical connectors, including, for example, power connectors, can include a housing, for example, an electrically insulative housing, and can include one or more electrically conductive conductors, for example, one or more power conductors. Power connectors are typically rated as a function of temperature rise above ambient temperature, measured in degrees Celsius (° C.) versus amperes (A) applied. Many conventional power connectors are current rated to a 30° C. rise time. For example, when a power connector temperature reaches 30° Celsius, the amount of current passing through the power connector at that time is the power limit of the power connector. Cooling the power connector permits the current rating to increase. 
     Heat-producing articles have been previously provided with thermal cooling by providing thermally conductive material, such as a graphene layer, substantially uniformly over a surface of the heat-producing articles. However, such implementations significantly increase manufacturing costs. Cooling may also be inefficient because heat is not purposefully directed in a predetermined direction away from the heat-producing articles. 
     EMI Management 
     Electronic components and electrical connectors can generate unwanted EMI, which can introduce unwanted signal noise into a system. Inductors, for example, can cause unwanted noise or unwanted crosstalk in neighboring components. As shown in prior art  FIGS.  10 A- 10 C , an inductor, coil, choke, or reactor  170  can include an electrically insulated wire wound into a coil  172  around a core. The coil  172  can define a first terminal at a first end of the electrically insulated wire, and a second terminal at a second end of the electrically insulated wire. The first and second terminals can connect to a substrate or another component, and therefore each of the first and second terminals protrude through or are accessible through corresponding holes or apertures in an inductor shield  178 . Inductors  170 , regardless of shielding, typically only include a first terminal  174  and a second terminal  176 . The inductor  170  can include a magnetic core (not shown), for example, an iron or ferrite core, inside the coil  172 . The inductor  170  can include a full or partial shield, for example, a magnetic shield, to minimize unwanted EMI if the inductor  170  is implemented as a power choke. 
     As shown in inductor  170  in  FIG.  10 C , the inductor shield  178  partially envelops or surrounds the coil (for example, coil  172  shown  FIG.  10 A ) and the core (not shown), and provides two corresponding openings (not shown) for egress of both the first terminal and the second terminal. Opposed airgaps, slits, crevices, recesses, or voids  180  are further defined in a first shield wall  182  and a second shield wall  186 , respectively. 
     SUMMARY OF THE INVENTION 
     Overview 
     According to an embodiment of the present invention, an electrical system includes a substrate and a slide-on stiffener that wraps around an edge of the substrate. 
     The electrical system can further include a first electrical connector positioned on the substrate. The first electrical connector can include an electrically dielectric housing and graphene, nanomaterial, or both graphene and nanomaterial, and the graphene, the nanomaterial, or both the graphene and the nanomaterial can be positioned asymmetrically about each of the X-, Y-, and Z-axes of the electrically dielectric housing, on the slide-on stiffener, or both the electrically dielectric housing and the slide-on stiffener. The first electrical connector can include a hold down, and the hold down can carry fusible elements prior to reflow of the first electrical connector onto the substrate. The first electrical connector can further include a fusible element that defines, prior to reflow onto the substrate, an apex and a nadir; a width of the fusible element at the apex can be narrower than a width of the fusible element at the nadir; and the apex can be positioned closer to the electrically dielectric housing than the nadir. An external shape of the fusible element can be sculpted or shaped with a laser. The first electrical connector can include a power conductor including a removable or non-removable clip positioned on a mating interface or mating surface of the power conductor. The electrical system can further include an inductor positioned on the substrate, wherein the inductor can include only a single slit, crevice, void, recess, or separation in the inductor shield, other than where first and second terminals of the inductor exit the inductor shield. 
     Mechanical Stress Management 
     To help control unwanted warping or bowing of a PCB, or to help maintain a coplanar surface of a PCB, slide-on substrate stiffeners are disclosed. The slide-on substrate stiffeners help to prevent or minimize bowing of a substrate that carries an electrical connector, an optical connector, module, coupler, a chip or die, etc. 
     According to an embodiment of the present invention, a slide-on substrate stiffener includes a first section, a second section that is perpendicular or substantially perpendicular to the first section, and a third section that is parallel or substantially parallel to the first section and is perpendicular or substantially perpendicular to the second section. The second section abuts or is adjacent to a corresponding edge of a first host substrate when the slide-on substrate stiffener is attached to the first host substrate. 
     The first and the third sections can extend in a same direction with respect to the second section. The slide-on substrate stiffener can further include a fourth section that extends perpendicular or substantially perpendicular to the first section and parallel or substantially parallel to the second section. The slide-on substrate stiffener can further include a fifth section that extends perpendicular or substantially perpendicular to the third section and parallel or substantially parallel to both the second section and the fourth section. The fourth section can be connected to a first end of the first section, and the first section and the second section can be connected at a second end of the first section opposite to the first end of the first section. The fifth section can be connected to a first end of the third section, and the third section and the second section can be connected at a second end of the third section opposite to the first end of the third section. 
     The first section, the second section, and the third section can each have a first width. The first host substrate can include a first electrical connector, and the first width can be approximately equal to a second width of a housing of the first electrical connector minus board alignment features of the housing of the first electrical connector. When the slide-on substrate stiffener is attached to the first host substrate, the first section can extend over the first electrical connector when viewed in plan and does not physically or electrically touch the first electrical connector. 
     The slide-on substrate stiffener can further include graphene and/or nanomaterial. In cross-section, the slide-on substrate stiffener can define a U-shape with opposed, parallel flared ends. The first section can define at least one hole, and the at least one hole can receive a fastener. The slide-on substrate stiffener can be toolless and may not include surface-mount technology (SMT), press-fit, or fastener mounts. 
     According to an embodiment of the present invention, a system includes the slide-on substrate stiffener of one of the various other embodiments of the present invention, the first host substrate, a first electrical connector positioned on the first host substrate, a second host substrate positioned parallel or substantially parallel to the first host substrate, and a second electrical connector positioned on the second host substrate. The first section, the second section, the third section, the fourth section, and the fifth section do not touch the first electrical connector, the second electrical connector, or the second host substrate. 
     The slide-on substrate stiffener can only physically touch one of the first host substrate or the second host substrate. The slide-on substrate stiffener can be frictionally and removably attached to the first host substrate. 
     To help prevent unwanted stress of a signal conductor or ground conductor SMT/substrate interface, hold downs, also referred to as board locks, can be configured with pre-formed solder units or fusible elements, carried by the hold downs prior to reflow, which eliminates the need for wave soldering or other separate soldering of the hold down to the PCB, decreasing processing time and reducing costs. 
     According to an embodiment of the present invention, a method of manufacturing a surface-mount hold down includes a step of attaching a first fusible element to either the surface-mount hold down or a hold-down base of the surface-mount hold down prior to reflow of the surface-mount hold down onto a first host substrate. 
     The method can further include a step of sizing individual fusible elements to increase a solder mass carried by either the surface-mount hold down or the hold down base of the surface-mount hold down. The method can further include a step of attaching second fusible elements to the surface-mount hold down or the hold down base of the surface-mount hold down. The method can further include a step of positioning the fusible element and the second fusible elements on the surface-mount hold down or the hold down base of the surface-mount hold down to increase a solder mass carried by the surface-mount hold down or the hold down base of the surface-mount hold down. 
     Some unique solder unit or fusible element cross-sectional shapes are also disclosed. These shapes help to reduce internal and external mechanical stresses on solder units or fusible elements reflowed onto a substrate. 
     According to an embodiment of the present invention, an electrical connector includes a housing, at least one electrical conductor, and a hold down that carries at least one first pre-formed fusible element. 
     The electrical connector can further include at least one second pre-formed fusible element physically connected to a mounting end of the at least one electrical conductor. When the electrical connectors is attached to a substrate, the at least one first pre-formed fusible element and the at least one second pre-formed fusible element can be configured to be reflowed onto the substrate during a same or a single reflow operation. 
     The at least one second pre-formed fusible element can define a cross-sectional shape selected from the group including: a cone, a triangle, an equilateral triangle, an isosceles triangle, an obtuse triangle, an acute triangle, a trapezoid, an acute trapezoid, an irregular quadrilateral, a concave hexagon that includes at least one reflex angle greater than 180°, an irregular hexagon that includes sides that are not equal in length and that includes one side that forms two intersecting line segments, a pentagon, a heptagon, an irregular octagon, a triangular prism, a triangular-based pyramid, tetrahedron, a square-based pyramid, a hexagonal pyramid shape, and a shape similar to the “OR” logic symbol. 
     A mounting end of the at least one electrical conductor can penetrate an apex of the at least one second pre-formed fusible element. 
     According to an embodiment of the present invention, a method of making a stronger solder connection includes reflowing or fusing a fusible element onto a respective mounting end of an electrical conductor, wherein the fusible element has a first external or cross-sectional shape; and subsequently sculpting the fusible element to form a second external or cross-sectional shape that is different than the first external or cross-sectional shape. 
     The method can further include a step of adding a non-wetting additive to the fusible element before or after the fusible element is sculpted. 
     Accordingly, cracking and shearing of reflowed fusible elements can be substantially eliminated by forming or placing, in cross-section, non-spherical fusible elements, solder slugs, solder charges, and the like, onto respective mounting ends of respective electrical conductors. 
     Heat Management 
     According to a preferred embodiment of the present invention, a heat-producing article includes a heat-dissipation material only selectively located on, or immediately adjacent to, the heat-producing article. 
     The heat-producing article can further include an electrically dielectric housing, wherein the heat-dissipation material can be graphene or nanomaterial, and the graphene or the nanomaterial can be positioned asymmetrically about X-, Y-, and Z-axes of the electrically dielectric housing. 
     The heat-dissipation material can be located at right angles with respect to other heat-dissipation material carried by the heat-producing article. 
     The heat-producing article can an electrical or optical interconnect, and the heat-dissipation material can be positioned on a plastic or electrically non-conductive housing of the electrical or optical interconnect. 
     Accordingly, the substrate or PCB, interconnects, etc. can operate at lower temperatures, which increases system efficiency and provides a longer useful life of the electrical system and its components. 
     According to an embodiment of the present invention, a heat-producing article includes a heat-dissipation material positioned on a plastic or electrically non-conductive portion of the heat-producing article. 
     According to an embodiment of the present invention, an electrical connector includes a housing and an electrical conductor carried by the housing. 
     The electrical connector can further including graphene or nanomaterial positioned on one or both of the housing and the electrical conductor. The electrical connector can further include a clip positioned on a mating end of the electrical conductor, wherein the clip can include more mating points of electrical contact than the mating end of the electrical conductor. The electrical connector can further include a fusible element positioned on a mounting end of the electrical conductor, wherein the fusible element can include an apex and a nadir, a width of the fusible element at the apex can be narrower than a width of the fusible element at the nadir, and the apex can be positioned closer to the housing than the nadir. 
     The removable clip can define or have more mating points of electrical contact than the mating end of the electrical conductor. More mating points of electrical contact can reduce contact resistance which, in turn, can lower the generation of unwanted Joule heating. 
     EMI Management 
     To help reduce unwanted EMI emissions from an electrical connector, or an electrical component such as an inductor, an inductor according to an embodiment of the present invention can include an inductor shield, a wound coil or a coil that has windings, a first coil end and a second coil end. The inductor shield can have at least one void or only a single void not occupied by the first coil end or the second coil end. The at least one void can be positioned, in its entirety, only beneath the windings of the coil. That is, the inductor shield can have a first inductor shield wall spaced from the coil, and a second inductor shield wall spaced from the coil and oriented parallel or substantially parallel within manufacturing tolerances to the first inductor shield wall. The second inductor shield wall can be spaced farther from the first coil end and the second coil end than the first inductor shield wall, and the at least one void can be defined by, or at least partially by, the first inductor shield wall. 
     According to an embodiment of the present invention, an inductor includes a coil including windings with a first terminal and a second terminal at opposite ends of the windings and an inductor shield. The inductor shield includes at least one void not occupied by the first terminal or the second terminal, and the at least one void is positioned only beneath all of the windings of the coil. 
     The above and other features, elements, characteristics, steps, and advantages of the present invention will become more apparent from the following detailed description of the embodiments of the present invention with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is side view of a system that has mating mezzanine electrical connectors, parallel first and second host substrates, and a pair of slide-on substrate stiffeners. 
         FIG.  1 B  is a top view of one end of the first host substrate of  FIG.  1 A . 
         FIG.  1 C  is a perspective view of the system of  FIG.  1 A . 
         FIG.  1 D  is a top view of the system of  FIG.  1 C . 
         FIG.  1 E  is a side view of the system of  FIG.  1 C . 
         FIG.  1 F  is a partial sectional view along lines A-A in  FIG.  1 D . 
         FIG.  1 G  is a partial cutaway view of the system of  FIG.  1 C . 
         FIG.  1 H  is a top view of the system of  FIG.  1 G . 
         FIG.  1 I  is a close-up partial view of the system of  FIG.  1 H . 
         FIGS.  1 J- 1 M  are perspective, top, side, and cross-sectional views, respectively, of a type-A, slide-on substrate stiffener. 
         FIGS.  1 N- 1 R  are top perspective, bottom perspective, bottom and top views, respectively, of a type-B, slide-on substrate stiffener. 
         FIGS.  1 S- 1 V  are top perspective, bottom perspective, bottom, top, side, and cross-sectional side views, respectively, of a modified type-B, slide-on substrate stiffener, shown in  FIGS.  1 N- 1 R . 
         FIG.  2 A  shows a hold down with solder units. 
         FIG.  2 B  shows a first solder unit pattern. 
         FIG.  2 C  shows a second solder unit pattern. 
         FIG.  2 D  shows a third solder unit pattern. 
         FIG.  2 E  shows a fourth solder unit pattern. 
         FIG.  3    is a side view of various fusible elements attached to respective mounting ends of electrical conductors. 
         FIG.  4    is a perspective top view of mating electrical conductors, for example, power conductors. 
         FIG.  5    is a perspective front view of heat-producing article, such as a power connector. 
         FIG.  6    is a top perspective view of mateable electrical connectors configured with graphene or nanomaterial. 
         FIG.  7    is a perspective side view of a first embodiment card edge connector with power contact clips. 
         FIG.  8    is a perspective bottom view of the clip shown in  FIG.  7   . 
         FIGS.  9 A and  9 B  are perspective side and perspective bottom views of a second embodiment card edge connector. 
         FIG.  9 C  is a perspective view of the second embodiment card edge connector of  FIGS.  9 A and  9 B , with the eighth housing removed for clarity. 
         FIGS.  10 A and  10 B  are transparent side views of a prior art inductor. 
         FIG.  10 C  is a schematic side view of the prior art inductor shown in  FIGS.  10 A and  10 B . 
         FIG.  10 D  is a schematic side view of an improved inductor. 
     
    
    
     DETAILED DESCRIPTION 
     Mechanical Stress Management 
     To help control unwanted substrate warpage or bowing, slide-on/slide-off substrate stiffeners for substrates, such as PCBs, are described below.  FIG.  1 A  shows a system  12 , that can include a first electrical connector or connectors  14  mounted to a first host substrate  16 , which can be any suitable substrate, including, for example, a computer processing unit (CPU) substrate, a computer processing module (CPM) substrate, or PCB. The first electrical connector  14  can be one half of mateable mezzanine connectors  18 . The other half of the mateable mezzanine connectors  18  can be a respective second electrical connector  20 . The second electrical connector  20  can be mounted to a second host substrate  24 , which can be any suitable substrate, including, for example, a carrier board or PCB. A first electrical connector  14  can mate with a respective one of the second electrical connectors  20 . The first host substrate  16  and the second host substrate  24  can be spaced apart by optional standoffs that can each include a respective standoff screw, for example standoff screw  22  in  FIG.  1 E . Slide-on/slide-off substrate stiffeners or slide-on only substrate stiffeners  26 , which are collectively referred to as slide-on substrate stiffeners  26 , can be configured to be slid over and wrap around a corresponding leading edge  28  of the first host substrate  16  or the second host substrate  24 . 
     A system  12  can include the first electrical connector  14  mounted to the first host substrate  16  and a slide-on substrate stiffener  26  removably attached to the first host substrate  16 . The slide-on substrate stiffener  26  can only physically contact the first host substrate  16  and not the second host substrate  24 , and can be configured to slide over and wrap around the corresponding leading edge  28  of the first host substrate  16 . 
     The first and second electrical connectors  14 ,  20  or the mateable mezzanine connectors  18  can be any separable mezzanine connectors, such as APM6/APF6, ADM6/ADF6, and COM HPC-compliant connectors manufactured and sold by Samtec, Inc., New Albany, Ind. The first and second electrical connectors  14 ,  20  can also be an LGA/BGA or double-sided LGA compression connector, such as ZRAY connectors, manufactured and sold by Samtec, Inc., New Albany, Ind. Each of the first and second electrical connectors  14 ,  20 , and any electrical connector described herein, can include any one or more of signal conductors, ground conductors, differential signal pairs, conductors arranged in a S-G-S-G, S-S-G-G, or S-S-G-S-S pattern, interleaved crosstalk shields, external EMI shields, latching, magnetic absorbing material, solder balls, compression mounts, press-fit pins, and hold downs or board locks. 
     Each slide-on substrate stiffener  26  can include a first panel or first section  30 , a second panel or second section  32  that can be perpendicular, substantially perpendicular within manufacturing tolerances, or at an angle between about 40° to about 90° to the first section  30  in an un-installed state, and a third panel or third section  34  that can be parallel or substantially parallel within manufacturing tolerances to the first section  30 . The third section  34  can be perpendicular, substantially perpendicular within manufacturing tolerances, or at an angle between about 40° to about 90°, with respect to the second section  32 , in an un-installed state. The third section  34  can extend substantially in the same direction, with respect to the second section  32 , as the first section  30 . A fourth ridge or fourth section  36  can extend perpendicular, substantially perpendicular within manufacturing tolerances, or at a non-zero angle with respect to the first section  30  and can extend parallel or substantially parallel within manufacturing tolerances to the second section  32 . A fifth ridge or fifth section  38  can extend perpendicular or substantially perpendicular within manufacturing tolerances to the third section  34 , and parallel or substantially parallel within manufacturing tolerances to both the second section  32  and the fourth section  36 . The fourth section  36  can be positioned at a first end  40  of the first section  30 , opposite an intersection of the first section  30  and the second section  32  at a second end of the first section  30  where the first section  30  and the second section  32  are connected. The fifth section  38  can be positioned at a first end  42  of the third section  34 , opposite an intersection of the third section  34  and the second section  32  at second end of the third section  34  where the third section  34  and the second section  32  are connected. In cross-section, in an installed or uninstalled state the slide-on substrate stiffener  26  can define a U-shape, with opposed, diverging ends. However, the slide-on substrate stiffener  26  can also define other cross-sectional shapes when installed or un-installed, including for example, a C-shape, a closed C-shape, or a triangular shape. Any one, at least one, at least two, or at least three of the first section  30 , the second section  32 , and the third section  34  can define at least one curved section in an installed or un-installed state. 
     The slide-on substrate stiffener  26 , such as the type-A slide-on stiffener  50  of  FIGS.  1 J- 1 M  and the type-B slide-on stiffener  52  of  FIGS.  1 N- 1 R  can be toolless, that is, the slide-on substrate stiffener  26  can be devoid of SMT mounts, press-fit mounts, and fastener receiving openings. The slide-on stiffener  26  can be retained on a substrate by friction or compression without compression fasteners. Any slide-on substrate stiffener  26  disclosed herein can include an electrically conductive material, an electrically non-conductive material (for example, plastic), a magnetic absorbing material, a thermally conductive material, or any combination of suitable materials. Any slide-on substrate stiffener  26  disclosed herein can include an elastomeric material. Any slide-on substrate stiffener  26  disclosed herein can frictionally and removably adhere to a respective first host substrate  16  or a respective second host substrate  24 . Alternatively, a shim (not shown) can be slid under the first section  30  and/or the third section  34 , and a substrate stiffener  26  disclosed herein can be held frictionally in place via a normal force exerted against the shim and the slide-on substrate stiffener  26 . 
     As shown in  FIG.  1 B , at least one or at least two of the first section  30 , the second section  32 , and the third section  34  can have a first width W 1  approximately equal to a second width W 2  of a corresponding first housing  46  of a first electrical connector  14  or a second housing of a second electrical connector  20 ; the first width W 1  of the slide-on substrate stiffener  26  can be less than a second width W 2  of a corresponding first housing  46  of a first electrical connector  14  or a second housing of a second electrical connector  20 ; a first width W 1  of the slide-on substrate stiffener  26  can be greater than a second width W 2  of a corresponding first housing  46  of a first electrical connector  14  or a second housing of a second electrical connector  20 ; or the first width W 1  of the first section  30  can be approximately equal to the second width W 2  of a corresponding first housing  46  of the first electrical connector  14 , minus board alignment features  44  of the first housing  46  of the first electrical connector  14 . First width W 1  of any one of the first, second, or third sections  30 ,  32 ,  34  of the slide-on substrate stiffener  26  can also be equal or approximately equal in numerical measurement value to second width W 2 . The first section  30  and the second section  32  can extend beyond the corresponding first housing  46  in the X1-direction. Any one, at least two, or all of the first section  30 , the second section  32 , and the third section  34  can extend over a boundary  48  of the board alignment features  44  or the corresponding first housing  46  or can be coincident with the boundary  48  in the Y1-direction. 
     If standoffs having standoff screws  22  ( FIG.  1 D ) are not desired due to complexity, cost, space limitations, etc., the first section  30  of a slide-on substrate stiffener  26  can snap over, circumscribe, or physically touch or snap over one or more protruding board alignment features  44 A of the first electrical connector  14  that extends or extend entirely through and protrude beyond a first surface  16 A of the first host substrate  16 , opposite to a second surface  16 B to which the first electrical connector  14  is attached. The protruding board alignment feature  44 A can act like a non-permanent retention pin or post that permits the first section  30  of the slide-on substrate stiffener  26  to be removably secured to the first host substrate  16 . Stated another way, the first section  30  can define at least one hole or recess ( 54 ,  FIG.  1 F ) that receives, or at least two holes or recesses that each receive, a corresponding protruding board alignment feature  44 A. 
     In another embodiment, the first section  30  can receive or releasably attach to at least respective portions of, or respective ends of a first standoff screw  22  ( FIG.  1 C ) or other externally threaded or non-threaded fastener that passes through the first host substrate  16  and into a corresponding standoff. A second standoff screw  22  ( FIG.  1 C ) can pass through the second host substrate  24  ( FIG.  1 A ) an into the same corresponding standoff as the first standoff screw  22  ( FIG.  1 C ). The first standoff screws  22  ( FIG.  1 C ) can each protrude beyond the first surface  16 A of first host substrate  16 . In this embodiment, the standoff screws  22  ( FIG.  1 C ) can collectively secure the first and second host substrates  16 ,  24  together, via a common standoff, and then the slide-on substrate stiffener  26  can be frictionally or compressibly attached to the first host substrate  16 . Alternatively, a standoff with a single standoff screw  22  ( FIG.  1 C ) is disclosed in U.S. Pat. No. 9,374,900, which is hereby incorporated by reference in its entirety. 
     With reference again to  FIG.  1 B , the first section  30  can extend over the first electrical connector  14 , but may be provided to not physically or electrically touch a respective one of the first electrical connector  14  or the second electrical connector  20  or a respective first housing  46  of the first electrical connector  14  or a second housing of the second electrical connector  20 . The second section  32  can abut or be positioned to extend perpendicular or substantially perpendicular within manufacturing tolerances to the leading edge  28  of the first host substrate  16  or the second host substrate  24 . In one embodiment, the first section  30 , the second section  32 , the third section  34 , the fourth section  36 , and the fifth section  38  do not touch the first electrical connector  14 , the second electrical connector  20 , or the second host substrate  24 . In another embodiment, the first section  30 , the second section  32 , the third section  34 , the fourth section  36 , and the fifth section  38  do not touch the first electrical connector  14 , the second electrical connector  20 , or the first host substrate  16 . In general, the slide-on substrate stiffener  26  can be provided to only physically touch the first host substrate  16 , only physically touch the second host substrate  24 , only physically touch the first substrate  16  and a standoff screw  22  ( FIG.  1 C ), or only physically touch the second host substrate  24  and a standoff screw  22  ( FIG.  1 C ). The slide-on substrate stiffener  26  can also be provided to only physically touch one of the first host substrate  16  or the second host substrate  24 . The slide-on substrate stiffener  26  can also be provided to only physically touch two opposed surfaces of the first host substrate  16  or the two opposed surfaces of the second host substrate  24 . 
       FIGS.  1 C and  1 D  show slide-on substrate stiffeners  26 , such as a type-A slide-on substrate stiffener  50  and a type-B slide-on substrate stiffener  52 . Either type of slide on substrate stiffener  50 ,  52 , or both, can be attached to the first host substrate  16  and the second host substrate  24 . The first host substrate  16  can be spaced from the second host substrate  24 . The type-A slide-on substrate stiffener  50  and the type-B slide-on substrate stiffener  52  can be held in place by friction or by standoff screws  22 . 
     Slide-on substrate stiffener  26 , such as type-B slide-on substrate stiffener  52 , is further shown in  FIG.  1 E . At least one of the mateable mezzanine connectors  18 , at least one of the standoff screws  22 , and at least one slide-on substrate stiffener  26  can each be carried by first host substrate  16 . The first host substrate  16  and the second host substrate  24  can each carry one or more of the standoff screws  22 . The mateable mezzanine connectors  18  can both be positioned between the first and second host substrates  16 ,  24 . Standoffs can both be positioned between the first and second host substrates  16 ,  24 . First host substrate  16  can be positioned between a first section  30  and a third section  34  of the slide-on substrate stiffener  26 . Second host substrate  24  can be positioned between the first section  30  and the third section  34  of the slide-on substrate stiffener  26 . 
     Turning to  FIG.  1 F , the first section  30  of the slide-on substrate stiffener  26  can define a first opening, orifice, recess, or hole  54 . The third section  34  of the slide-on substrate stiffener  26  can define a second hole  54 A coincident with the first hole  54 A. A respective standoff screw  22  can extend through both the first hole  54  and the second hole  54 A. Even if the respective standoff screw  22  is removed from the corresponding first and second holes  54 ,  54 A, the slide-on substrate stiffener  26  can still stiffen the respective first host substrate  16  or the second host substrate  24 . That is, as discussed above, the slide-on substrate stiffener  26  can maintain a friction or elastic compression fit with a substrate, even if the respective standoff screw  22  is removed from the slide-on substrate stiffener  26  and a respective one of the first host substrate  16  or second host substrate  24 . Accordingly, the slide-on substrate stiffener  26  can produce a normal force on a respective first or second host substrate  16 ,  24  by itself, without other external attachments for example, fasteners, epoxies, glues, and welds. The normal force can be exerted onto a first surface  16 A or a second surface  16 B of a first host substrate  16 , or some structure such as a wedge or shim carried by the first host substrate  16  or the second host substrate  24 , creating a friction force. The slide-on substrate stiffener  26  can therefore remain attached to a respective first host substrate  16  or a second host substrate  24 , even if all other external attachments, for example, fasteners, epoxies, glues, and welds connecting the slide-on substrate stiffener  26  to a respective first host substrate  16  or second host substrate  24  are all completely removed. Alternatively, the slide-on/slide-off substrate stiffener can be slid onto a respective first host substrate  16  or second host substrate  24  and then be permanently attached to the first host substrate  16  or the second host substrate  24  by glue, epoxy, weld, and the like. 
     As shown in  FIGS.  1 G- 1 I , a first host substrate  16  and a second host substrate  24  can be oriented parallel or substantially parallel to one another, within manufacturing tolerances. The first host substrate  16  and the second host substrate  24  can be connected by at least one pair of mateable mezzanine connectors  18  and standoff screws  22 . Any suitable mateable mezzanine connectors  18  can be used, such as those described herein. The standoff screws  22  can be used to ensure a consistent distance between the first host substrate  16  and the second host substrate  24 , and to attach a slide-on substrate stiffener  26  to the first host substrate  16 . 
     Type-A slide-on substrate stiffeners  50  are shown in various views in  FIGS.  1 J- 1 M . Each type-A slide-on substrate stiffener  50  can define a first section  30 , a second section  32 , and a third section  34 . The first and third sections  30 ,  34  can be oriented parallel or generally parallel to one another within manufacturing tolerances, and the second section  32  can be oriented perpendicular or generally perpendicular to both the first and third sections  30 ,  34  within manufacturing tolerances. The third section  34  can be perpendicular, substantially perpendicular within manufacturing tolerances, or at an angle between about 60° to about 90°, with respect to the second section  32 . The third section  34 A can extend in the same direction, with respect to the second section  32 , as the first section  30 , and can also be perpendicular, substantially perpendicular within manufacturing tolerances, or at an angle between about 60° to about 90°, with respect to the second section  32 . 
     One or more of the first, second, and third sections  30 ,  32 ,  34  can be devoid of holes that are configured to receive a respective board alignment feature or standoff screw. Type-A slide-on stiffeners can be configured to be friction or compression or snap or press or adhesively fit onto a substrate, such as the first host substrate  16 . 
     Type-B slide-on substrate stiffeners  52  are shown in various views of  FIGS.  1 N- 1 R  and can be structurally similar to the type-A slide-on substrate stiffeners  50 . However, type-B slide-on substrate stiffeners  52  can each define a first hole  54  or a first and second hole  54 ,  54 A ( FIGS.  1 N- 1 P and  1 R ). Each of the type-B slide-on substrate stiffeners  52  can include a first section  30 , a second section  32  that can be perpendicular or substantially perpendicular within manufacturing tolerances to the first section  30 , and a third section  34 A that can be oriented parallel or substantially parallel within manufacturing tolerances to the first section  30 . The third section  34 A can be perpendicular, substantially perpendicular within manufacturing tolerances, or at an angle between about 60° to about 90°, with respect to the second section  32 . The third section  34 A can extend in the same direction, with respect to the second section  32 , as the first section  30 , and can also be perpendicular, substantially perpendicular within manufacturing tolerances, or at an angle between about 60° to about 90°, with respect to the second section  32 . 
     Each of the first and second holes  54 ,  54 A in the type-B slide-on substrate stiffener  52  can be offset, and can lie on a first line that is not parallel to the second side  32 . One or both of the first and second holes  54 ,  54 A can receive a portion of a respective standoff screw  22 . Even if the standoff screws  22  are removed, the type-B slide-on substrate stiffener  52  can maintain a friction or elastic compression fit with a substrate. The third section  34 A of the type-B slide-on substrate stiffener  52  can be contoured with the holes  54 ,  54 A only provided in the first section  30 . Alternatively, the third section  34 A of the type-B slide-on substrate stiffener  52  can include one or two holes that correspond to the first and second holes  54 ,  54 A in the first section  30 . Stated another way, a portion of the third section  34 A can extend parallel to and coincident with a portion of the first section  30 , creating an overlap. Everywhere the third section  34 A overlaps the first section  30 , the third section  34 A, the third section can be devoid of a completed circumscribed first hole  54  or second hole  54 A. Alternatively, the third section  34 A can include one or more holes, such as first or second holes  54 ,  54 A that each receive a respective standoff screw  22 . 
       FIGS.  1 S- 1 V  each show a modified type-B slide-on substrate stiffener  52 A. The modified type-B slide-on substrate stiffener  52 A can include a first section  30 , a second section  32 , and a third section  34 B. The first section  30  can define one or more holes, such as a first hole  54 , a second hole  54 A, a third hole  54 B, and a fourth hole  54 C. The second section  32  can be perpendicular or substantially perpendicular within manufacturing tolerances to the first section  30 . The third section  34 B that can be oriented parallel or substantially parallel within manufacturing tolerances to the first section  30 . The third section  34 B can be perpendicular, substantially perpendicular within manufacturing tolerances, or at an angle between about 60° to about 90°, with respect to the second section  32 . The third section  34 B can extend in the same direction, with respect to the second section  32 , as the first section  30 , at an angle between about 60° to about 90°, with respect to the second section  32 . 
     Each of the first and second holes  54 ,  54 A in the modified type-B slide-on substrate stiffener  52 A can be offset, and can lie on a first line that is not parallel to the second side  32 . Third and fourth holes  54 B,  54 C can lie on a second line that is not parallel to the second side  32  or the first line. One or more of the first, second, third and fourth holes  54 ,  54 A,  54 B,  54 C can each receive a portion of a respective standoff screw  22 . Even if the standoff screws  22  are removed, the modified type-B slide-on substrate stiffener  52 A can maintain a friction or elastic compression fit with a substrate. The third section  34 B of the modified type-B slide-on substrate stiffener  52 A can be contoured, with the first, second, third and fourth holes  54 ,  54 A,  54 B,  54 B only provided in the first section  30 . Alternatively, the third section  34 B of the modified type-B slide-on substrate stiffener  52 A can include one or more holes that each align with and correspond to a respective one of the first, second, third and fourth holes  54 ,  54 A,  54 B,  54 C in the first section  30 . Stated another way, a portion of the third section  34 B can extend parallel to and coincident with a portion of the first section  30 , creating an overlap. Everywhere the third section  34 B overlaps the first section  30 , the third section  34 B, the third section  34 B can be devoid of a completed circumscribed first hole  54  or a second hole  54 A or a third hole  54 B or a fourth hole  54 C. Alternatively, the third section  34 B can include one or more holes, such as first, second, third or fourth holes  54 ,  54 A,  54 B,  54 C that each receive a respective standoff screw  22 . 
     Board coplanarity and rigidity can be helped or maintained by the slide-on substrate stiffeners  26  discussed above. Mechanical rigidity of a connector or electrical component can be helped or maintained with a weld tab or hold down  56 , such as those shown in  FIGS.  2 A- 2 E , that carries at least one pre-formed fusible element  58 . A weld tab or hold down  56  an be physically attached to an electrical component or an interconnect, such as an electrical connector that can have SMT mounting ends with pre-formed fusible elements  58  or compression mounting ends. 
       FIG.  2 A  shows a weld tab or hold down  56  that can carry at least one, at least two, at least three, at least four, at least five, or at least six pre-formed solder slugs, solder points, solder charges, solder crimps, solder balls, and/or solder units, which are referred to herein, individually or collectively, as fusible elements  58 . A hold down base  60  can define none, at least one, at least two, at least three, at least four, at least five, or at least six dimples  62 , recesses, or holes that can each receive a corresponding one of the fusible elements  62 . The hold down  56  fusible elements  58  can be configured to be reflowed onto substrate, for example, third host substrate  72  in  FIG.  3   , and can self-center, at the same time as an associated or attached interconnect, electrical connector, or component (not shown) is reflowed onto the substrate. That is, a hold down  56  with fusible elements  58  can be attached to any surface mount technology (SMT) connector or electrical component, and the entire electrical connector and hold down assembly can be reflowed onto a substrate at the same time or during the same reflow operation. Both the electrical connector, such as first and second connectors  14 ,  20  discussed above, and the hold down  56  can simultaneously carry respective fusible elements  58 . An electrical connector is not limited to a mezzanine connector, and can be a co-planar and right-angled connector. 
     Fusible elements  58  disclosed herein can be pre-reflowed onto the hold down  56  or hold down base  60 , adhered to the hold down  56  or hold down base  60 , mechanically attached to the hold down  56  or hold down base  60  by a crimping operation, a coining operation, a pressing operation, a swaging operation, adhesive, and the like. A size or width of the fusible elements  58  disclosed herein can be reduced to fit more, smaller fusible elements  58  onto the hold down  56  or can be increased to fit fewer, larger fusible elements  58  onto the hold down  56  or the hold down base  60 . Larger sized fusible elements  58 , as compared to fusible elements  58  carried by a hold down  56  or an associated interconnect, electrical connector, or component can also act as a standoff of the associated interconnect, electrical connector, or component. The fusible elements  58  can also be doped with other metals, additives, or impurities such as gold, so that the fusible elements  58  carried by the hold down  56  or hold down base  60  can melt slightly before or after, in time, solder balls on the associated interconnect, electrical connector, or component melt, but during the same reflow operation. Fusible elements  58  can be lead free. The fusible elements may be shaped by a laser, which provides a carbon residue on a surface of the fusible elements that helps the fusible elements retain their shape during the reflow operation. 
       FIG.  2 B  shows a first pattern  64  of fusible elements  58  that can be attached to the hold down  56  of  FIG.  2 A . The first pattern  64  of fusible elements  58  can extend along an axis X 2 , i.e., a first axis in  FIG.  2 B , and can all be symmetrical about the axis X 2 .  FIG.  2 C  shows a second pattern  66  of fusible elements  58  that can extend along the axis X 2 , i.e., a first axis in  FIG.  2 C . At least one of the fusible elements  58  can be positioned asymmetrically about the axis X 2 , and at least two of the fusible elements  58  can be positioned symmetrically about the axis X 2 .  FIG.  2 D  shows a third pattern  68  of fusible elements  58 , divided into a first group of fusible elements  58  that can extend along the axis X 2 , i.e., a first axis in  FIG.  2 D , and a second group of fusible elements  58  that can extend along an axis X 3 , i.e., a second axis in  FIG.  2 D . In this embodiment, the axis X 2  can extend parallel to the axis X 3 . The fusible elements  58  can each be smaller in an external dimension as compared to any one of the fusible elements  58  shown in  FIGS.  2 B and  2 C . At least one, at least two, or at least three of the fusible elements  58  can be positioned symmetrically with respect to the axis X 2  and at least one, at least two, or at least three of the fusible elements  58  can be positioned symmetrically with respect to the axis X 3 .  FIG.  2 E  shows a fourth pattern  70  of fusible elements  58  that can extend along the second axis X 2 , i.e., a first axis in  FIG.  2 E . In this embodiment, all of the fusible elements  58  are positioned asymmetrically with respect to the second axis X 2 . 
     A method can include a step of attaching a fusible element  58  to a hold down  56  or a hold down base  60  of the hold down  56  prior to reflow of the fusible element  58  onto a substrate, for example, the third host substrate  72  in  FIG.  3   . Another step can include sizing individual fusible elements  58  to significantly increase a total or cumulative mass of solder carried by the hold down  56  or the hold down base  60  of the hold down  56 . Another step can include attaching fusible elements  58  to a hold down  56  or a hold down base  60 . Another step can include positioning individual fusible elements  58  on a hold down  56  or hold down base  60  to significantly increase a total or cumulative solder mass carried by the hold down  50  or hold down base  60 . The fusible elements  58  can be reflowed onto a substrate, for example, the third host substrate  72  in  FIG.  3   , during the same or a single reflow operation. Another step can include fitting both an electrical connector and a hold down  56  carried by the electrical connector with fusible elements  58 , prior to reflow of the electrical connector, the hold down  56 , and the fusible elements  58  onto a substrate, for example, the third host substrate  72  in  FIG.  3   . 
     As shown in  FIG.  3   , fusible elements  58 A,  58 B,  58 C,  58 D can each define a shape, in cross-section or in 3-D, prior to reflow onto a substrate, that is not a sphere, ellipsoid, cylinder, circle, ellipse, square or rectangle. Cross-sectional shapes of the reflowed fusible elements  58 A,  58 B,  58 C,  58 D include, for example, a cone, a triangle, an equilateral triangle, an isosceles triangle, an obtuse triangle, an acute triangle, a trapezoid, an acute trapezoid, an irregular quadrilateral, a concave hexagon that includes at least one reflex angle greater than 180°, an irregular hexagon that includes sides that are not equal in length and that includes one side that forms two intersecting line segments, a pentagon, a heptagon, an irregular octagon, a triangular prism, a triangular-based pyramid, tetrahedron, a square-based pyramid, a hexagonal pyramid shape, and a shape similar to the “OR” logic symbol. 
     Fusible elements  58 A,  58 B,  58 C,  58 D can be reflowed or formed or fused onto a respective mounting end  84  of an electrical conductor  86 , with the mounting end  84  penetrating through a nadir  78 ,  78 A,  78 B,  78 C of the respective fusible element  58 A,  58 B,  58 C,  58 D and extending into a body of each respective fusible elements  58 A,  58 B,  58 C,  58 D. Stated another way, each fusible element  58 A,  58 B,  58 C,  58 D is positioned only on one side or surface of a mounting end  84  of an electrical conductor  86 , on only two sides or surfaces of a mounting end  84  of an electrical conductor  86 , on only three sides or surfaces of a mounting end  84  of an electrical conductor  86 , or on at least four sides or surfaces of a mounting end  84  of an electrical conductor  86 . In general, each respective fusible element  58 A,  58 B,  58 C,  58 D is impaled through a respective apex by a respective mounting end  84 , into a body of the respective fusible element  58 A,  58 B,  58 C,  58 D. 
     In general, the shape of each fusible element  58 A,  58 B,  58 C,  58 D can be defined by respective first solder surfaces  74 ,  74 A,  74 B,  74 C and second solder surfaces  76 ,  76 A,  76 B,  76 C that each converge at a respective apex  78 ,  78 A,  78 B,  78 C and diverge at a respective nadir  80 ,  80 A,  80 B,  80 C, where the apex  78 ,  78 A,  78 B,  78 C is positioned in, on, or adjacent to a third housing  82 , for example, an electrically non-conductive electrical connector housing. Each respective nadir  80 ,  80 A,  80 B,  80 C can be positioned adjacent to the third host substrate  72  or corresponding pads carried by the third host substrate  72 . That is, each fusible element  58 A,  58 B,  58 C,  58 D can be narrower in width at the top, near the respective apex  78 ,  78 A,  78 B,  78 C, than at the bottom near the respective nadir  80 ,  80 A,  80 B,  80 C, defining a shape that points toward an electrically insulative third housing  82  of an electrical connector or component. Each respective apex  78 ,  78 A,  78 B,  78 C can be positioned closer in distance to the third housing  82  than the corresponding nadir  80 ,  80 A,  80 B,  80 C, and can be spaced farther from the third substrate  72  or pads of the third host substrate  72  than the corresponding, respective nadir  80 ,  80 A,  80 B,  80 C. The narrowest width portion of the fusible elements  58 A,  58 B,  58 C,  58 D, which can be defined as a width across the respective fusible elements  58 A,  58 B,  58 C,  58 D, measured parallel to a bottom of the third housing  82 , can be attached to a solder tail or mounting end  84  of an electrical conductor  86 . Each fusible element  58 A,  58 B,  58 C,  58 D can be wider at the respective nadir  80 ,  80 A,  80 B,  80 C or bottom surface of the respective fusible element  58 A,  58 B,  58 C,  58 D that is farthest in distance from the third housing  82 . Each respective first solder surface  74 ,  74 A,  74 B,  74 C and each corresponding, respective second solder surface  76 ,  76 A,  76 B,  76 C can intersect at a corresponding apex  78 ,  78 A,  78 B,  78 C and diverge at each corresponding, respective nadir  80 ,  80 A,  80 B,  80 C. The first surfaces  74 ,  74 A,  74 B,  74 C and second solder surfaces  76 ,  76 A,  76 B,  76 C can both be linear, can both curve, or one surface can be linear and the other surface can curve. 
     Without being bound by theory, it is believed that when fusible elements  58 A,  58 B,  58 C,  58 D with narrower apexes  78 ,  78 A,  78 B,  78 C and wider nadirs  80 ,  80 A,  80 B,  80 C are reflowed onto a third host substrate  72 , the resulting solder joint is mechanically stronger that if using fusible elements that define a cross-sectional shape selected from a sphere, an ellipsoid, a cylinder, a circle, an ellipse, a square or a rectangle. When fusible elements  58 A,  58 B,  58 C,  58 D are reflowed or re-reflowed to attach an electrical component to the third substrate  72 , unwanted mechanical or thermal stress fractures between the fusible elements  58 A,  58 B,  58 C,  58 D and the substrate, such as the third substrate  72  or pads on the third substrate  72 , are reduced. 
     In another embodiment, a method of making a stronger solder connection can include a step of reflowing or fusing a fusible element  58 A,  58 B,  58 C,  58 D onto a respective mounting end  84  of an electrical conductor  86 , wherein the reflowed or fused fusible element  58 A,  58 B,  58 C,  58 D has or defines a first external or cross-sectional shape. Another step can include subsequently sculpting the fusible element  58 A,  58 B,  58 C,  58 D to form or define a second external or cross-sectional shape that is different than the first external or cross-sectional shape. Another step can include adding a non-wetting additive to one or more surfaces of the fusible element  58 A,  58 B,  58 C,  58 D after the fusible element  58 A,  58 B,  58 C,  58 D is sculpted. Another step can include, after the step of sculpting or after the step of adding a non-wetting agent, reflowing the fusible element  58 A,  58 B,  58 C,  58 D with the second external or cross-sectional shape onto a substrate. 
     Fusible elements  58 A,  58 B,  58 C,  58 D can each define any geometrical shape, such as a general spherical shape after being reflowed or fused onto a respective mounting end  84  of an electrical conductor  86 . At least one or more of the fusible elements  58 A,  58 B,  58 C,  58 D can have a hardness or metallurgy equal to the hardness of a pre-lasered or standard solder ball, both prior to being reflowed or fused onto a respective mounting end  84  and after being reflowed or fused onto a respective mounting end  84 . After being reflowed or fused onto a corresponding respective mounting end  84 , at least one of the fusible elements  58 A,  58 B,  58 C,  58 D can be sculpted, such as manually, thermally, or with a laser beam to create any geometrical, external or cross-sectional shape other than a sphere with a constant radius. Non-restrictive, exemplary shapes can include, in cross-section or in 3-D, prior to reflow onto a substrate, an ellipsoid, a cylinder, an ellipse, a square, a rectangle, a cone, a triangle, an equilateral triangle, an isosceles triangle, an obtuse triangle, an acute triangle, a trapezoid, an acute trapezoid, an irregular quadrilateral, a concave hexagon that includes at least one reflex angle greater than 180°, an irregular hexagon that includes sides that are not equal in length and that includes one side that forms two intersecting line segments, a pentagon, a heptagon, an irregular octagon, a triangular prism, a triangular-based pyramid, tetrahedron, a square-based pyramid, a hexagonal pyramid shape, and a shape similar to the “OR” logic symbol. 
     One or more surfaces of the fusible element  58 A,  58 B,  58 C,  58 D can be coated with a non-wetting agent, such as solder masking ink, before or after sculpting or laser sculpting, to help prohibit the wetting of select surfaces and help maintain the post-sculptured shape of the fusible element  58 A,  58 B,  58 C,  58 D through and after reflow of the fusible element  58 A,  58 B,  58 C,  58 D onto a substrate. 
     Heat Management 
     Unwanted heat and differing coefficients of thermal expansion (CTEs) between components and a PCB can cause unwanted mechanical stress and solder joint failure. When components are attached to a substrate with fixed solder joints, and the components and the substrate expand at different rates because of differing CTEs, the fixed solder joints can be stressed. Unwanted heat can also cause components or interconnects to fail or have a reduced useful life. So, controlling unwanted heat has advantages. 
     As shown in  FIGS.  4  and  5   , heat-dissipation material  88 , for example, graphene or nanomaterial strips, layers, sheets, or coatings can be selectively placed on, or immediately adjacent to, heat-producing structures or articles  90 , such as transceivers, electrical connectors, power conductors, optical engines, etc. Power contacts  92  are shown, but other heat-producing components, including, for example, VCSELs, optical engines, and the like, can be used. Nanomaterials can include any material that includes nanoparticles. Heat-dissipation material such as graphene, nanomaterials or both can also be added to slide-on substrate stiffeners and hold downs disclosed above, or the clips described below. 
     A heat-producing article  90 , such as an electrical connector that produces unwanted heat, can include heat-dissipation material  88 , an electrical conductor such as a power contact  92 , and a dielectric or electively conductive housing, such as housing  94 . The heat-dissipation material  88 , such as graphene or nanomaterials, can be selectively placed such that unwanted heat is directed in a pre-determined direction away from the heat-producing article  90 . Selective placement can include not positioning or coating on substantially an entire top, bottom, side, or end of a heat-producing article  90 . Selective placement can include positioning multiple, at least two, at least three, at least four, at least five, or five or more discrete segments of heat-dissipation material  88  that are each separated by regions that are devoid of heat-dissipation material  88 . Selective placement can include positioning heat-dissipation material  88  such that a single line cannot be drawn between three or more discrete or distinct segments or discrete or distinct areas of heat-dissipation material  88 . Selective placement can include positioning discrete segments, portions, or areas of heat-dissipation material  88  non-sequentially along an axis or line. Selective placement can include positioning discrete segments, portions, or areas of heat-dissipation material  88  so that the discrete segments, portions, or areas are not immediately adjacent to one another along an axis or line. Selective placement can include positioning discrete segments, portions, or areas of heat-dissipation material  88  so that the segments, portions, or areas do not physically touch one another along an axis or line. These techniques may be used singly or in combination. 
     A method to dissipate heat can include a step of placing a heat-dissipation material  88  on a heat-producing article  90  to dissipate heat H away from the heat-producing article  90 . Another step can include thermally evaluating a heat-producing article  90  to determine where unwanted heat H is being generated. Another step can include selectively positioning a heat-dissipation material  88 , for example, graphene or a nanomaterial, only where unwanted heat is being generated by the heat-producing article  90 . Another step can include selectively directing heat H away from where unwanted heat H is being produced, generated, or observed by thermal detection equipment in a heat-producing article  90  through the use of a heat-dissipation material  88  to a predetermined point in space, to predetermined points in space, to where heat H can be better tolerated or removed. A heat-dissipation material  88 , for example, graphene or nanomaterial, can be applied to a heat-producing article  90  to direct the heat H to a predetermined point in space, where it can then be removed by conduction, convection, forced fluid, cooling fluid, and the like. 
     As shown in  FIG.  5   , another step can include selectively positioning all of the heat-dissipation material  88 , for example, graphene or nanomaterial, asymmetrically about an X-axis and a Y-axis of a heat-producing article  90 , for example, power contacts  92  and a housing  94 . Another step can include positioning all of the heat-dissipation material  88 , for example, graphene or nanomaterial, asymmetrically about an X-axis and a Z-axis of the heat-producing article  90 , for example, power contacts  92  and the housing  94 . Another step can include positioning all of the heat-dissipation material  88 , for example, graphene or nanomaterial, asymmetrically about a Y-axis and a Z-axis of the heat-producing article  90 , for example, power contacts  92  and a housing  94 . Another step can include selectively positioning all of the heat-dissipation material  88 , for example, graphene or nanomaterial, asymmetrically about each of the X-, Y-, and Z-axes of a heat-producing article  90 , for example, power contacts  92  and a housing  94 . The housing  94  can include glass-reinforced nylon, plastic, and the like. Graphene or nanomaterials can be attached to a metal, an electrically non-conductive material or housing, a plastic, a housing, or any combination thereof. The heat-dissipation material  88  can be arranged on an electrically non-conductive housing  94  or on power contacts  92  carried by the housing  94  such that at least on portion or section of the heat-dissipation material  88  is not positioned sequentially with respect to an immediately adjacent portion or section of the heat-dissipation material  88  or does not physically touch an immediately adjacent portion or section of the heat-dissipation material  88 . The heat-dissipation material  88  can also have different sizes or shapes, or can be non-identical or visually different than another heat-dissipation material carried by a common connector or article  90  or a common housing  94 . The heat-dissipation material  88  can be positioned on more than one end or side of the housing  94  or power contact  92 . 
     Another step can include selectively positioning all of the heat-dissipation material  88 , for example, graphene or nanomaterial, symmetrically about an X-axis and a Y-axis of a heat-producing article  90 , for example, power contacts  92  and a housing  94 . Another step can include positioning all of the heat-dissipation material  88 , for example, graphene or nanomaterial, symmetrically about an X-axis and a Z-axis of the heat-producing article  90 , for example, power contacts  92  and a housing  94 . Another step can include positioning all of the heat-dissipation material  88 , for example, graphene or nanomaterial, symmetrically about a Y-axis and a Z-axis of the heat-producing article  90 , for example, power contacts  92  and a housing  94 . Another step can include selectively positioning all of the heat-dissipation material  88 , for example, graphene or nanomaterial, symmetrically about all of X-, Y-, and Z-axes of a heat-producing article  90 , for example, power contacts  92  and a housing  94 . Graphene or nanomaterials can be attached to a metal, an electrically non-conductive material or housing, a plastic, a housing, or any combination thereof. 
     Another step can include selectively positioning all of the heat-dissipation material  88 , for example, graphene or nanomaterial, asymmetrically about the X-axis of the heat-producing article  90 , for example, power contacts  92  and a housing  94 . Another step can include selectively positioning all of the heat-dissipation material  88 , for example, graphene or nanomaterial, asymmetrically about the Y-axis of the heat-producing article  90 , for example, power contacts  92  and a housing  94 . Another step can include selectively positioning all of the heat-dissipation material  88 , for example, graphene or nanomaterial, asymmetrically about the Z-axis of the heat-producing article  90 , for example, power contacts  92  and a housing  94 . Graphene or nanomaterials can be attached to a metal, an electrically non-conductive material or housing, a plastic, a housing, or any combination thereof. 
     Another step can include selectively positioning all of the heat-dissipation material  88 , for example, graphene or nanomaterial, symmetrically about the X-axis of the heat-producing article  90 , for example, power contacts  92  and a housing  94 . Another step can include selectively positioning all of the heat-dissipation material  88 , for example, graphene or nanomaterial, symmetrically about the Y-axis of heat-producing article  90 , for example, power contacts  92  and a housing  94 . Another step can include selectively positioning all of the heat-dissipation material  88 , for example, graphene or nanomaterial, symmetrically about the Z-axis of the heat-producing article  90 , for example, power contacts  92  and a housing  94 . Graphene or nanomaterials can be attached to a metal, an electrically non-conductive material or housing, a plastic, a housing, or any combination thereof. 
     As shown in  FIG.  6   , mateable, right-angle electrical connectors  18 A can include a first electrical connector  112 , for example, a receptacle electrical power connector, and a second electrical connector  114 , for example, a plug electrical power connector.  FIG.  6    shows examples of mateable, right-angle electrical connectors, but any suitable connectors can be used, and this disclosure and any claimed inventions are not limited to any specific electrical connectors  18 A shown in  FIG.  6   . This disclosure applies to mezzanine and coplanar connectors as well. Other high- or low-power plug and mating receptacle connectors may be implemented within the scope of the embodiments of the present invention, for example, the power connector shown in  FIG.  7    and the EDGE RATE, RAZOR BEAM, Q RATE, POWERSTRIP, and MPOWER power connectors, all commercially available from SAMTEC, Inc., New Albany, Ind. and all hereby incorporated by reference in their entireties. Furthermore, many other types of power connector can be provided with significant thermal improvement by implementing graphene, nanomaterials, or both graphene and nanomaterials as discussed herein with respect to the embodiments of the present invention. 
     With continuing reference to  FIG.  6   , the first electrical connector  112  can include two portions  116  for two groups of power conductors  120 , a housing, for example, electrically insulative housing  118 , inner power conductors  122 , outer power conductors  124 , a spacer  126 , conductor mating ends  128  and graphene or nanomaterials  130 . Second electrical connector  114  can include a housing, for example, electrically insulative housing  132 , three second electrical connector conductors  134 ,  136 ,  138 , and press-fit or solder tails  140 . However, the mating electrical connectors  18 A are not limited to the inner power conductors  122  and the outer power conductors  124 , and single power conductors may be included. 
     Nanomaterial  130  can be an electrically conductive or an electrically non-conductive material. The nanomaterial  139  can be the AMPASHIELD-THERMAL™ brand nano-carbon material, commercially available from CAMETICS, Ltd. A nanomaterial  130  can be positioned on one, on at least one, only on one, on two, on at least two, only on two, on three, on at least three, only on three, on four, on at least four, only on four, on five, on at least five, only on five, on six, on at least six, only on six, on seven, on at least seven, only on seven, on eight, on at least eight, only on eight, on nine, on at least nine, and only on nine, or on ten of the group that includes an external surface ES 1  of the housing  118 ; an internal surface IS 1  of the housing  118 ; a first surface FS 1  and a second surface FS 2  of the conductor mating ends  128  or other areas of the power conductors  120 , the inner power conductors  122 , and the outer power conductors  124 ; a third surface TS 2  and a fourth surface FS 4  of one or more of the second electrical connector conductors  134 ,  136 ,  138 ; on or adjacent to at least one tail surface TS of the press-fit or solder tails  140 ; a second external surface ES 2  and a second internal surface IS 2  of the housing  132 ; and a first host substrate or second host substrate to which the first electrical connector  112  or the second electrical connector  114  are mounted. 
     A method can include a step of positioning, spraying, transferring, or applying a nanomaterial on one, on at least one, only on one, on two, on at least two, only on two, on three, on at least three, only on three, on four, on at least four, only on four, on five, on at least five, only on five, on six, on at least six, only on six, on seven, on at least seven, only on seven, on eight, on at least eight, only on eight, on nine, on at least nine, and only on nine, or on ten of the group that includes: an external surface ES 1  of the housing  118 ; an internal surface IS 1  of the housing  118 ; a first surface FS 1  and a second surface FS 2  of the conductor mating ends  128  or other areas of the power conductors  120 , the inner power conductors  122 , and the outer power conductors  124 ; a third surface TS 2  and a fourth surface FS 4  of one or more of the second electrical connector conductors  134 ,  136 ,  138 ; on or adjacent to at least one tail surface TS of the press-fit or solder tails  140 ; a second external surface ES 2  and a second internal surface IS 2  of the housing  132 ; and a first host substrate or second host substrate to which the first electrical connector  112  or the second electrical connector  114  are mounted. 
     Jointly or separately with respect to the nanomaterials discussed above, contact resistance and unwanted Joule heating of an electrical conductor, such as a power conductor can be reduced by placing a removable or non-removable clip on a power conductor, for example, a mating interface of a power conductor. The clip can be retrofit on existing power conductors or electrical connectors, providing more power throughput at the same temperature rise time. 
     As shown in  FIG.  7   , an electrical connector, such as power connector  142  can include an electrically insulative seventh housing  144 , at least one or a plurality of electrical conductors, such as power contacts  146 , and at least one conductor arm  148 . A cover, guard, overlay, barred frame, or clip  150 , such as a removable or separable clip  150 , can be added to, attached to, hung on, affixed to, or received by a mating end  152  of a respective one of the at least one respective conductor arm  148 . While the mating end  152  defines an existing contact surface that engages a corresponding contact surface of a mating electrical conductor, corresponding fingers  160  of clip  150  can form at least one, at least two, at least three, or four or more new respective replacement contact surfaces that physically, electrically, or physically and electrically contact a mating electrical conductor. The replacement contact surfaces can be physically spaced from the existing contact surface. The replacement contact surfaces can each physically, electrically, or physically and electrically contact a corresponding pad of a card  154 , a corresponding mating electrical conductor of a mating connector, or another clip  150  carried by a mating electrical conductor. Power contacts  146  equipped with or retrofitted with one or more respective clips  150  can be carried by a card-edge connector  166  that is able to receive an edge of a card  154 . Electrical conductors such as power contacts  146  can also be carried by a co-planar connector, mezzanine connector, or right-angled connector. The clip  150  can be retrofitted to an existing electrical conductor, such as a respective signal, ground, or power contact  146 , wherein a power contact  146  with the clip  150  can carry more power or current at a 30° C. rise time than the same power contact  146  without the clip  150 . A signal conductor or a pair of differential signal conductors with the clip  150  can pass signals with less reflection, insertion loss, return loss, or impedance mismatch compared to a signal conductor or a pair of differential signal conductors that do not have clip  150  or respective clips  150 . 
       FIG.  8    shows an isolated view of the clip  150 . Clip  150  can be made from an electrically conductive material, such as a stamped and formed beryllium copper, an alloy, a heat absorbing material, a magnetic absorbing material, or an electrically conductive or electrically non-conductive substrate coated with an electrical conductive material. The clip  150  can include a first retention portion  156 , a second retention portion  158  spaced from the first retention portion  156 , and at least one, at least two, at least three or at least four rigid or compliant spring arms or fingers  160  that can each extend between the first retention portion  156  and the second retention portion  158 . Each finger  160  can be attached to the clip  150  at only one end or at both opposed ends. Each finger  160  can define a curve or arc from one end of the finger  160  to the other end of the finger  160 . A replacement contact surface can be defined at an apex of the curve or arc. Fingers  160  can each be spaced apart spring arms, compliant beams or a single stamping that defines a one or more parallel slits that mechanically weaken a single stamped beam, and fingers  160  can be configured to connect electrically, physically, or both electrically and physically with a single mating power conductor, a stamped mating power conductor, or a mating power conductor that also defines at least one, at least two, at least three, at least four or spring arms or fingers  160 . 
     The first retention portion  156  can include one or more first arms or friction arms  162  that frictionally or otherwise hold the clip  150  on a corresponding mating end  152 , as shown in  FIG.  7   , of a conductor arm  148 , and one or more second arms or friction arms  164  configured to frictionally or otherwise hold the clip  150  at another portion of the corresponding mating end  152 , as shown in  FIG.  7   , of the conductor arm  148 . The clip  150  can be removable, or can be attached to a corresponding electrical conductor, such as power contact  146 , via a semi-permanent or permanent attachment, such as soldering, welding, or laser welding. 
     The clip  150  can at least double, at least triple, at least quadruple, at least quintuple, at least sextuple, at least septuple, at least octuple, at least nonuple, at least decuple, at least undecuple, etc. the number of points of physical contact, electrical contact, or both physical and electrical contact as compared to an electrical conductor, power contact  146 , or conductor arm  148  without the clip  150 . Contact resistance, along with unwanted heat, can be reduced by the clip  150 , which increases the number of physical or electrical contact points between two mating electrical conductors, as compared to a single beam power contact  146  without the clip  150 . Each clip  150  adds more electrically conductive material to a power contact  146  or a mating end  152  of an electrical conductor or power contact  146 , which also helps to reduce heat. Air can also circulate, to some degree, between the fingers  160  and the corresponding mating end  152  or existing contact surface of the conductor arms  148 . 
       FIGS.  9 A and  9 B  show top and bottom perspective views of a card-edge connector  166 , which is a modification of the power connector  142  shown in  FIG.  7   . As shown in  FIGS.  9 A and  9 B , the card-edge connector  166  can include an electrically insulative housing  168  and at least one or a plurality of power contacts  146 A. 
       FIG.  9 C  is a perspective view of the card-edge connector  166  shown in  FIGS.  9 A and  9 B  with the housing removed. As shown in  FIG.  9 C , the card-edge connector  166  can further include a power contact  146 A having at least one conductor arm  148 A. As discussed above, a clip  150  can be added, attached, removably attached, permanently attached, or electrically attached to a mating end  152 A of one or more of the at least one respective conductor arms  138 A. Signal conductors  169  are also shown. 
     According to the above steps and features, location(s) of unwanted heat can be determined, and the unwanted heat can be selectively directed by a heat-dissipation material, for example, graphene or metamaterial. A step can include placing a heat-dissipation material non-uniformly on a heat-producing article to dissipate heat away from the heat-producing article. An electrical connector can include any three, or any four, or five of a group including a housing, an electrical conductor such as a power contact, a clip positioned on a mating end of the electrical conductor, a nanomaterial or graphene carried by the electrical connector or the housing, and a non-spherical, in cross-section and prior to reflow onto a substrate, fusible element positioned adjacent to a mounting end of the electrical conductor. 
     EMI Management 
       FIGS.  10 C and  10 D  show the differences between a known fully shielded inductor (for example, prior art inductor  170  of  FIGS.  10 A- 10 C ) and an inductor  170 A according to an embodiment of the present in invention. 
     Referring to  FIG.  10 D , other than the openings in the inductor shield  178 A that are filled by the first terminal (not shown) and the second terminal (not shown), the inductor shield  178 A of the inductor  170 A can define only a single slit, crevice, void, recess, or separation  180 A in the inductor shield  178 A. The single slit, crevice, void, recess, or separation  180 A in the inductor shield  178 A can be defined in a first shield wall  182 A that extends parallel or substantially parallel within manufacturing tolerances to a base substrate  184 A and is spaced closest in distance to a mounting base substrate  184  that receives the first and second terminals. That is, the inductor shield  178 A is devoid of a slit, crevice, void, recess, or separation in any other shield wall, for example, second shield wall  186 A, other than shield wall  182 A. 
     Referring to Prior Art  FIGS.  10 A- 10 C , the airgap, slit, crevice, recess, or void  180  on the top or second shield wall  186  of the fully shielded inductor  170  creates a strong, and unwanted, magnetic field above the inductor  170 . This unwanted EMI can degrade the signal integrity of components within the magnetic field. Conversely, the inductor  170 A shown in FIG.  10 D does not include any airgap, slit, crevice, recess, or void in the second shield wall  186 A, and thus unwanted EMI emissions from the inductor  170 A are significantly reduced. 
     Comparing Prior Art  FIGS.  10 A- 10 C  with  FIG.  10 D , a primary difference is that  FIG.  10 D  shows a single void  180 , and Prior Art  FIGS.  10 A- 10 C  show a pair of voids  180 . Otherwise, the inductor  170 A is otherwise structurally similar to inductor  170 . Inductor  170 A can include a wound coil  172  as shown in  FIG.  10 A  and an inductor shield  178 A as shown in  FIG.  10 D . The wound coil  172  of  FIG.  10 A  can have a first terminal  174  as shown in  FIG.  10 B  and a second terminal  176  as shown in  FIG.  10 B  at opposite ends of the wound coil  172  or windings as shown in  FIG.  10 A . The inductor shield  178 A can include at least one void  180  not occupied by the first terminal  174  shown in  FIG.  10 B  or the second terminal  176  shown in  FIG.  10 B , and the at least one void  180  can be positioned only beneath all of the windings of the wound coil  172  shown in  FIG.  10 A  positioned inside the inductor shield  178 A shown in  FIG.  10 D . 
     While the disclosure has been described with reference to the embodiments, it will be understood by those skilled in the art that various changes may be implemented, and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, modifications may be implemented to adapt a particular system, device, or component thereof to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the disclosure is not limited to the embodiments described herein, but that the disclosure will include all embodiments falling within the scope of the appended claims. 
     The terminology used herein is for the purpose of describing the embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope of the disclosure. The described embodiments were chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.