Patent Publication Number: US-2011070750-A1

Title: Electrical connector having a sequential mating interface

Description:
BACKGROUND OF THE INVENTION 
     The subject matter herein relates generally to interconnecting circuit boards, and more particularly, to electrical connector assemblies that are configured to electrically couple arrays of contacts. 
     Some electrical systems, such as servers, routers, and data storage systems, utilize electrical connector assemblies for transmitting signals and/or power through the electrical system. The electrical connector assemblies are used to interconnect various electrical components together, such as circuit boards, chip carriers or similar substrates that are circuitized or metallized. The electrical components typically have a grip array of contacts, to which the electrical connector assemblies are connected. The electrical connector assemblies typically include a substrate having contacts arranged on both sides thereof for interfacing with the grid arrays of the electrical components. 
     However, known electrical connector assemblies are not without disadvantages. For instance, the interfaces between the grid arrays are complex and may include more than one type of contact, such as power contacts, signal contacts and/or ground contacts. During mating, all of the contacts interface simultaneously. However, in some applications it may be preferred to have the different types of contacts mating at different times during the mating sequence. Therefore, a need exists for an electrical interface assembly having different subsets of contacts that connect and disconnect with one or more electrical components at different times. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one embodiment, an interconnect assembly is provided for interconnecting first and second electrical components. The interconnect assembly includes a substrate having opposed first and second surfaces. The interconnect assembly also includes a first array of contacts on the first surface for engaging corresponding elements on the first electrical component. The first array of contacts have first and second subsets that extend different first and second distances from the substrate to define a compressible interface that sequentially mates with the first electrical component such that the first subset of the contacts engages the first electrical component prior to engagement by the second subset of contacts. The interconnect assembly further includes a second array of contacts on the second surface for engaging corresponding elements on the second electrical component. 
     Optionally, the contacts of the first array of contacts may include a beam extending between a base and a tip portion, where some of the contacts have different lengths than other contacts. The contacts of the first array of contacts may define an outer mating interface and an inner mating interface arranged closer to the first surface of the substrate than the outer mating interface. The contacts of the first subset of contacts have a first length and the contacts of the second subset of contacts having a second length shorter than the first length. The contacts of the first array of contacts may include beams extending at an angle with respect to the first surface, with each of the beams being at approximately the same angle. At least some of the beams may have different lengths. Some of the beams may be angled at a first angle and other beams being angled at a different angle. 
     Optionally, the first array of contacts may include a first subset of contacts having mating ends spaced apart from the first surface by a first distance, and a second subset of contacts having mating ends spaced apart from the first surface by a second distance. The first subset of contacts may engage the elements of the first electrical component prior to the second subset of contacts. The first array of contacts may include a third subset of contacts having mating ends spaced apart from the first surface by a third distance. The second subset of contacts may engage the elements of the first electrical component prior to the third subset of contacts. At least one of the first, second and third subsets of contacts may include power contacts. The first subset of contacts may include ground contacts, and the second subset of contacts may include signal contacts. The second subset of contacts may include sensing contacts. 
     In another embodiment, an interconnect assembly for interconnecting first and second electrical components is provided that includes a substrate having opposed first and second surfaces, primary contacts defining a mating interface above the first surface for engaging corresponding elements on the first electrical component where the primary contacts are elevated above the first surface by a first distance, and secondary contacts defining a mating interface above the first surface for engaging corresponding elements on the first electrical component where the secondary contacts are elevated above the first surface by a second distance. The primary contacts and the secondary contacts define a compressible interface having the primary contacts making initial engagement with the elements of the first electrical component and the secondary contacts making subsequent engagement with the elements of the first electrical component. 
     In a further embodiment, an interconnect assembly is provided for interconnecting first and second electrical components. The interconnect assembly includes a substrate having opposed first and second surfaces, and a plurality of contacts extending from the first surface for engaging corresponding elements on the first electrical component. The contacts include beams having predetermined lengths that are angled from the first surface at predetermined angles. The lengths and the angles are selected such that the contacts are elevated above the first surface at different heights to engage the elements of the electrical component according to a sequenced mating scheme. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an electrical system formed in accordance with one embodiment. 
         FIG. 2  is a cross-sectional view of a primary circuit board and a moveable interconnect assembly that may be used with the electrical system shown in  FIG. 1 . 
         FIG. 3  is a front perspective view of an electrical connector assembly for the electrical system shown in  FIG. 1 . 
         FIG. 4  is a cross-sectional view of the electrical connector assembly shown in  FIG. 3 . 
         FIG. 5  illustrates an alternative electrical system that utilizes an interconnect assembly formed in accordance with an alternative embodiment. 
         FIG. 6  is a side view of the interconnect assembly shown in  FIG. 5 . 
         FIG. 7  is a cross-sectional view of an interconnect assembly formed in accordance with an exemplary embodiment. 
         FIG. 8  is a cross-sectional view of another alternative interconnect assembly. 
         FIG. 9  is a cross-sectional view of yet another alternative interconnect assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a perspective view of an electrical system  300  formed in accordance with one embodiment that includes an electrical connector assembly  310  used to interconnect first and second electrical components  304 ,  306  together. In the illustrated embodiment, the first electrical component  304  represents a circuit board and may be referred to hereinafter as a primary circuit board  304 . The second electrical component  306  also represents a circuit board and may be referred to hereinafter as a secondary circuit board  306 . The electrical connector assembly  310  may be used to interconnect electrical components other than circuit boards together in alternative embodiments. 
     The secondary circuit board  306  has a mating surface  307  and the electrical connector assembly  310  is coupled to the surface  307  of the secondary circuit board  306 . The secondary circuit board  306  and the electrical connector  310  together define removable card connector assembly  302  that is removably coupled to the primary circuit board  304 . The electrical connector assembly  310  includes a separable mating interface  312  that is configured to be separably coupled to the primary circuit board  304 . In particular, the mating interface  312  is configured to be mated with a system contact array  320  of contacts along a surface  305  of the primary circuit board  304 . 
     As one example for the electrical system  300 , the card connector assembly  302  may be a part of a server blade and the primary circuit board  304  may be a mother board of a server system. However, the electrical system  300  shown in  FIG. 1  may be a variety of other electrical systems, such as a router system or data storage system. Furthermore, although the illustrated embodiment is described with reference to interconnecting the primary and secondary circuit boards  304  and  306 , the description herein is not intended to be limited to circuit boards. Embodiments described herein may be used to interconnect other electrical components where one component has an array of contacts and the other component has a complementary array of contacts. For example, embodiments described herein may be used as an interconnect assembly between an electrical component such as a circuit board and an integrated circuit (IC) component, such as a chip. 
     When the card connector assembly  302  and the primary circuit board  304  are to be engaged, the card connector assembly  302  may be advanced in a longitudinal mating direction along the primary circuit board  304 . For example, the card connector assembly  302  may slidably engage guiding features  315 , and slide to a predetermined position and orientation with respect to the contact array  320 . Once the card connector assembly  302  is properly positioned alongside the contact array  320 , the mating interface  312  may be moved to engage the contact array. 
     The electrical connector assembly  310  includes a circuit assembly  314  having the mating interface  312 , one or more moveable interconnect assemblies  318 , and one or more flexible circuits  316 . The circuit assembly  314  communicatively couples the primary and secondary circuit boards  304  and  306  by providing conductive paths therebetween. The interconnect assemblies  318  are configured to be moved toward and away from the contact array  320  of contacts on the primary circuit board  304 . As will be discussed in greater detail below, embodiments described herein are configured to move the interconnect assembly  318  between a retracted position and an engaged position. When in the engaged position, the electrical connector assembly  310  is electrically coupled to the contact array  320  through the interconnect assembly  318 . Accordingly, the electrical connector assembly  310  is configured to interconnect the primary and secondary circuit boards  304  and  306 . The electrical connector assembly  310  may be similarly moved to the retracted position by separating the interface with the primary circuit board  304 . The electrical connector system  310  may be removed from the electrical system  300  when disengaged from the primary circuit board  304 . 
     As shown in  FIG. 1 , the electrical connector assembly  310  is affixed to the secondary circuit board  306  and movable to engage the primary circuit board  304 . However, in alternative embodiments, the electrical connector assembly  310  may be affixed to the primary circuit board  304  and be configured to engage a secondary circuit board when the secondary circuit board is inserted into the electrical system  300 . 
       FIG. 2  is a cross-sectional view illustrating the interconnect assembly  318  in a retracted position (shown in dashed lines) and in an engaged position (solid lines) with respect to the primary circuit board  304 . The circuit assembly  314  (shown in  FIG. 1 ) is configured to allow the interconnect assembly  318  to be moved bi-directionally in a linear manner between the retracted position and the engaged position. As shown, the contact array  320  of the primary circuit board  304  has contacts  322  and the interconnect assembly  318  has contacts  332 . The contacts  332  have different lengths such that mating interfaces of different contacts  332  engage the contacts  322  at different stages of mating. A sequenced mating interface is defined by the different length contacts  332 . In the retracted position, the contacts  332  of the interconnect assembly  318  are spaced from corresponding contacts  322  of the primary circuit board  304 . In the engaged position, each contact  332  is electrically coupled to or engaged to one of the contacts  322 . The interconnect assembly  318  may be held and moved toward the primary circuit board  304  until the corresponding the contacts  322  and  332  are engaged. The longer contacts  332  engage the contacts  322  first, and the shorter contacts  332  engage the contacts  322  at a later time. The interconnect assembly  318  may also be disengaged from the primary circuit board  304 . 
     The interconnect assembly  318  may be moved toward the primary circuit board  304  in a linear manner. Alternatively, the interconnect assembly  318  may be moved toward and engage the primary circuit board  304  in a non-linear manner. For example, the interconnect assembly  318  may approach the primary circuit board  304  at an angle or along a rotated path until the contacts  322  and contacts  332  become aligned and engaged. The board surface  305  and the mating surface  328  may not be parallel when in the retracted position, but may become aligned and parallel with each other when the interconnect assembly  318  is in the engaged position. 
       FIG. 3  is a front perspective view of the mating interface  312  of the electrical connector assembly  310 . The electrical connector assembly  310  may include a base frame  408  and a coupling mechanism  404  that is supported by the base frame  408 . The base frame  408  may be coupled (e.g., fastened) to the secondary circuit board  306  (shown in  FIG. 1 ) so that the base frame  408  has a fixed relationship with respect to the secondary circuit board  306 . The electrical connector assembly  310  includes the circuit assembly  314  that includes the flexible circuits  316  coupled to the mating interface  312 . The circuit assembly  314  also includes the interconnect assembly  318  and another interconnect assembly  413 . The flexible circuits  316  (also called flex circuit sections) are coupled to the interconnect assembly  413  at a board side  496  of the electrical connector assembly  310  and extend around the electrical connector assembly  310  to the mating interface  312 . 
     The coupling mechanism  404  is configured to move the mating interface  312  between the retracted and engaged positions. The coupling mechanism  404  includes an axle  430  and cams  432  coupled to the axle  430 . The cams  432  are either directly or indirectly coupled to the interconnect assembly  318 . The axle  430  is rotated to move the cams  432 , and thus the mating interface  312  between the retracted and engaged positions. Other types of mechanisms may be used in alternative embodiments to move the separable interface at the mating interface  312  between the retracted and engaged positions. 
       FIG. 4  is cross-sectional view of the electrical connector assembly  310 . As shown, the flexible circuit  316  extends around the coupling mechanism  404  to communicatively couple the interconnect assembly  413  on the board side  496  to the interconnect assembly  318  of the mating interface  312 . More specifically, the flexible circuit  316  extends around a perimeter of the cross-section of the electrical connector assembly  310  from the interconnect assembly  413  along non-mating sides  452  and  453 . The flexible circuit  316  and/or the circuit assembly  314  may include rigid substrates or board stiffeners  456  for supporting and providing a shape to the flexible circuit  316 . 
     The interconnect assemblies  318  and  413  and the flexible circuit  316  of the circuit assembly  314  may be assembled together into one unit. The interconnect assembly  413  extends between and engages the flexible circuit  316  on one side of the interconnect assembly  413  and the secondary circuit board  306  (shown in  FIG. 1 ) on the other side of the interconnect assembly  413 . The contacts of the interconnect assembly  413  may include contact beams, press-fit contacts or solder-ball contacts that are affixed to the secondary circuit board  306  to maintain an electrical connection with the secondary circuit board  306 . Alternatively, other types of contacts may be used. 
     The mating interface  312  includes the interconnect assembly  318 . The interconnect assembly  318  extends between and engages the flexible circuit  316  on one side of the interconnect assembly  318  and engages the primary circuit board  304  (shown in  FIG. 1 ) on the other side of the interconnect assembly  318 . The contacts  332  of the interconnect assembly  318  include the beams extending from the interconnect assembly  318  for engaging the primary circuit board  304 . Alternatively, the contacts  332  may extend directly from the flexible circuit  316  for engagement with the primary circuit board  304 . 
       FIG. 5  illustrates an alternative electrical system  510  that utilizes an interconnect assembly  512  formed in accordance with an exemplary embodiment. The interconnect assembly  512  is used to interconnect a first electrical component  514  with a second electrical component  516 . In the illustrated embodiment, the electrical component  514  is represented by an integrated circuit (IC) component such as an electronic package in the form of a chip or other circuitized module. The electrical component  516  is represented by a printed circuit board (PCB). The electronic package and PCB are merely illustrative of exemplary electrical components that may be interconnected by the interconnect assembly  512 . Other types of electrical components may be similarly interconnected by the interconnect assembly  512  in alternative embodiments. For example, the interconnect assembly  512  may be used to interconnect two PCBs or two electronic packages in alternative embodiments. 
     The electrical component  514  includes a component mating face  518  for mating with the interconnect assembly  512 . The component mating face  518  includes an array of mating elements, such as conductive pads, traces or contacts. The mating elements are arranged in a predetermined pattern for mating with the interconnect assembly  512 . The electrical component  516  includes a component mating face  522  for mating with the interconnect assembly  512 . The component mating face  522  includes an array of mating elements  524 , such as conductive pads, traces or contacts. The mating elements  524  are arranged in a predetermined pattern for mating with the interconnect assembly  512 . 
     The interconnect assembly  512  includes a substrate  526  and a socket frame  528  holding the substrate  526 . The socket frame  528  may be attached to the electrical component  516  to position the interconnect assembly  512  with respect to the electrical component  516 . The socket frame  528  is configured to hold the electrical component  514  therein. The electrical component  514  may be directly secured to the socket frame  528 , or alternatively, a fastener or plate may be used to secure the electrical component  514  to the socket frame  528  and/or the electrical component  516 . The socket frame  528  may be used to position the electrical component  514  with respect to the interconnect assembly  512 . 
       FIG. 6  is a side view of the interconnect assembly  512  illustrating the substrate  526  with the socket frame  518  (shown in  FIG. 5 ) removed for clarity. Optionally, the interconnect assembly  512  may be utilized without the use of the socket frame  518  to interconnect the electrical components  514 ,  516  (shown in  FIG. 5 ). 
     The interconnect assembly  512  includes opposed first and second surfaces  530 ,  532 . When assembled, the first surface  530  generally faces the electrical component  514  and the second surface  532  generally faces the electrical component  516 . The interconnect assembly  512  includes a first array of contacts  534  provided on and/or extending from the surface  530 . The contacts  534  are configured to electrically connect to corresponding mating elements on the electrical component mating face  518  (shown in  FIG. 5 ). The interconnect assembly  512  includes a second array of contacts  536  provided on and/or extending from the surface  532 . The contacts  536  are configured to electrically connect to corresponding mating elements  524  (shown in  FIG. 5 ) on the second electrical component mating face  522  (shown in  FIG. 5 ). 
     In an exemplary embodiment, the contacts  534  are separately provided from, and electrically connected to, the contacts  536 . Alternatively, the contacts  534  may be integrally formed with the contacts  536  such that a portion of each contact is provided at the surface  530  and a portion of each contact is also provided at the surface  532 . In the illustrated embodiment, the contacts  534  may represent spring contacts extending from the surface  530  and the contacts  536  may represent solder balls extending from the surface  532 . Other types of contacts may be provided at either surface  530 ,  532  in alternative embodiments. 
       FIG. 7  is a cross-sectional view of a portion of another interconnect assembly  12 . The interconnect assembly  12  may be used within the electrical system  300  (shown in  FIG. 1-4 ), such as to replace the interconnect assembly  318  and/or the interconnect assembly  413 , or any other interface therein depending on the particular application. Similarly, the interconnect assembly  12  may be used within the electrical system  510  (shown in  FIGS. 5-6 ) to replace the interconnect assembly  512 . The components and features of the interconnect assembly  12  may be used in whole or in part within the other interconnect assemblies or interfaces described herein. 
     The interconnect assembly  12  is used to interconnect a first electrical component  14  with a second electrical component  16 . The electrical component  14  includes a component mating face  18  for mating with the interconnect assembly  12 . The component mating face  18  includes an array of mating elements  20 , such as conductive pads, traces or contacts. The electrical component  16  includes a component mating face  22  for mating with the interconnect assembly  12 . The component mating face  22  includes an array of mating elements  24 , such as conductive pads, traces or contacts. In the example of the electrical system  300 , the first electrical component  14  may represent the primary circuit board  304  or the secondary circuit board  306  and the second electrical component  16  may represent the flexible circuit  316 . 
     The interconnect assembly  12  includes a substrate  26  having opposite first and second surfaces  30 ,  32 . When assembled, the first surface  30  generally faces the electrical component  14  and the second surface  32  generally faces the electrical component  16 . The interconnect assembly  12  includes a first array of contacts  34  provided on and/or extending from the surface  30 . The contacts  34  are configured to electrically connect to corresponding mating elements  20  on the electrical component mating face  18 . In the example of the electrical system  300 , the contacts  34  may represent the contacts  322 . 
     The interconnect assembly  12  includes a second array of contacts  36  provided on and/or extending from the surface  32 . The contacts  36  are configured to electrically connect to corresponding mating elements  24  on the second electrical component mating face  22 . In an exemplary embodiment, a via pad  40  and coverlay  42  are applied to the surface  32  of the substrate  26 . The contacts  36  are electrically and mechanically connected to the via pad  40 . 
     The contacts  34  are secured to the substrate  26  by an adhesive  44 . A coverlay  46  extends over portions of the contacts  34 . Optionally, the contacts  34  may form part of a flexible circuit overlaying a rigid substrate. The contacts  34  extend outward from the flexible circuit for mating with the mating elements  20 . In an exemplary embodiment, conductive traces  48  are provided on and/or routed through the substrate  26  to interconnect the contacts  34  and the contacts  36 . Optionally, vias or through holes  50  may extend through the substrate  26 , and the conductive traces  48  may extend from the surface  30  to the surface  32  through the via  50 . A group of the contacts  34  may be electrically connected to corresponding ones of the contacts  36  by a dedicated conductive trace  48 . 
     Each contact  34  includes a beam  60  extending between a base  62  and a tip portion  64 . The end of the beam  60  may be curved such that the end of the tip portion  64  is positioned below another region of the tip portion  64 . The base  62  is securely coupled to the substrate  26 , such as by the adhesive  44 . The base  62  is electrically connected to the conductive trace  48  to create the electrical path to the contacts  36 . Optionally, a separate conductive element (not shown) may be provided between the contact  34  and the conductive trace  48  to create a conductive path therebetween. 
     The beam  60  of each contact  34  is angled at an angle  66  such that the tip portion  64  is elevated from the surface  30 . Optionally, each of the beams  60  may have the same, or substantially the same, angle  66 . Alternatively, some of the beams  60  may be angled at different angles  66  than other beams  60 . The contacts  34  are resilient and may be flexed towards the surface  30  during mating with the electrical component  14 . For example, when the tip portions  64  engage the electrical component  14  the beams  60  are compressed toward the surface  30 . The contacts  34  thus define a compressible interface for mating with the electrical component  14 . 
     The beams  60  of the contacts  34  have a length  68  measured between the base  62  and the tip portion  64 . In an exemplary embodiment, some of the contacts  34  have different lengths  68  than other contacts  34 . As such, the tip portions  64  of some contacts  34  may be elevated higher above the surface  30  than other of the contacts  34 . The tip portion  64  defines the highest point of the beam  60  above the surface  30 . As noted above, the end of the beam  60  may not necessarily be the highest point of the beam  60  as the end of the tip portion may be curved downward. The highest point of the beam  60  is the portion of the beam  60  that engages the electrical component  14 . The length  68  and the angle  66  control the position of the highest point of the beam  60 . 
     The contacts  34  are configured into multiple types of contacts, namely primary contacts  70  and secondary contacts  72 .  FIG. 7  illustrates an example of a primary contact  70  and a secondary contact  72 . The primary contacts  70  form one subset and the secondary contacts  72  form another subset. The primary contact  70  has a length  68  that is longer than the length  68  of the secondary contact  72  such that the primary contact  70  extends to a point further from the substrate  26  than the secondary contact  72 . Additionally, or alternatively, the primary contact  70  may have an angle  66  that is greater than the angle  66  of the secondary contact  72  such that the primary contact  70  extends to a point further from the substrate  26  than the secondary contact  72 . 
     The tip portion  64  of the primary contact  70  is elevated above the surface  30  by a first distance  74 . The tip portion  64  of the secondary contact  72  is elevated above the surface  30  by a second distance  76 . The tip portion  64  of the primary contact  70  defines an outer mating interface  78  at or near a mating end  80  of the primary contact  70 . The mating interface  78  is elevated above the surface  30  by the first distance  74 . The primary contacts  70  are oriented such that the mating interfaces  78  of the primary contacts  70  are generally coplanar with one another. The tip portion  64  of the secondary contact  72  defines an inner mating interface  82  at or near a mating end  84  of the secondary contact  72  that is elevated above the surface  30  by the second distance  76 . The secondary contacts  72  are oriented such that the mating interfaces  82  of the secondary contacts  72  are generally coplanar with one another. 
     The primary contacts  70  engage corresponding mating elements of the electrical component  14  prior to the secondary contacts  72  engaging corresponding mating elements of the electrical component  14  due to the fact that the outer mating interfaces  78  of the primary contacts  70  are disposed further from the surface  30  than the inner mating interfaces  82  of the secondary contacts  72 . The primary contacts  70  make initial engagement with the mating elements and the secondary contacts  72  make subsequent engagement with the mating elements  20 . By controlling the length  68  and/or the angle  66  of the beams  60 , the height of the tip portions  64  above the surface  30  may be controlled to provide a compressible interface that sequentially mates with the electrical component  14 . 
     The contacts  34  may constitute different types of contacts. For example, the contacts  34  may be signal contacts, ground contacts, power contacts, sensing contacts, and the like. The primary contacts  70  may include one or more types of contacts and the secondary contacts  72  may include one or more types of contacts. 
     In one exemplary embodiment, the primary contacts  70  may be power contacts and the secondary contacts  72  may be signal contacts and ground contacts. During mating with the electrical component  14 , the primary contacts  70  and the secondary contacts  72  are sequentially mated with the power contacts being mated prior to the signal and ground contacts. As such, power may be transmitted across the primary contacts  70  prior to signals being transmitted across the secondary contacts  72 . 
     In another exemplary embodiment, the primary contacts  70  may be ground contacts and the secondary contacts  72  may be signal contacts. During mating with the electrical component  14 , the primary contacts  70  and the secondary contacts  72  are sequentially mated with the ground contacts being mated prior to the signal contacts. As such, the electrical components  14 ,  16  may be grounded with one another prior to signals being transmitted across the secondary contacts  72 . 
     In a further exemplary embodiment, the primary contacts  70  may be power contacts, signal contacts and/or ground contacts and the secondary contacts  72  may be sensing contacts. During mating with the electrical component  14 , the primary contacts  70  and the secondary contacts  72  are sequentially mated with the power contacts, signal contacts and/or ground contacts being mated prior to the sensing contacts. When the sensing contacts are mated with the electrical component  14 , a signal indicating that the electrical components  14 ,  16  are fully mated may be transmitted across the sensing contacts, which may then allow power and/or signals to be transmitted across the primary contacts  70 . For example, in such an embodiment, the electrical components  14 ,  16  do not transmit power and/or data until a signal from the sensing contacts is transmitted across the mating interface, which indicates that all contacts are mated as the sensing contacts are the last contacts to mate. Other configurations and arrangements of contacts are possible in alternative embodiments. Additionally, other layers of contacts may be used in alternative embodiments for sequential mating of more than two mating interfaces. The other layers may be positioned closer to the mating surface  30  or further from the mating surface  30  than the mating interfaces  78  and/or  82 . 
       FIG. 8  is a cross-sectional view of an alternative interconnect assembly  112 . The interconnect assembly  112  is similar to the interconnect assembly  12  but includes three layers of mating interfaces  110  for sequenced mating with the electrical component  14 . The interconnect assembly  112  includes primary contacts  114 , secondary contacts  116  and tertiary contacts  118 . Each of the contacts  114 ,  116 ,  118  includes beams  120  extending from a base  122  to a tip portion  124 . Different mating interfaces  110  are defined by the tip portions  124  for mating with mating elements of the electrical component  14 . 
     The tip portions  124  of the primary contacts  114  are elevated above a first surface  126  of a substrate  128  of the interconnect assembly  112  by a first distance  130 . The tip portions  124  of the secondary contacts  116  are elevated above the surface  126  by a second distance  132  that is less than the first distance  130 . The tip portions  124  of the tertiary contacts  118  are elevated above the surface  126  by a third distance  134  that is less than the second distance  132 . The tip portions  124  of the primary contacts  114  are generally coplanar with one another and define an outer mating interface that initially mates with the mating elements of the electrical component  14 . The tip portions  124  of the secondary contacts  116  are generally coplanar with one another and mate with corresponding mating elements prior to the tip portions  124  of the tertiary contacts  118  mating with corresponding mating elements  20 . By controlling a length and/or an angle of the beams  120  of the various contacts  114 - 118 , the height of the tip portions  124  above the surface  126  may be controlled to provide a compressible interface that sequentially mates with the electrical component  14 . 
       FIG. 9  is a cross-sectional view of another alternative interconnect assembly  212 . The interconnect assembly  212  is similar to the interconnect assembly  12  but includes contacts  214  that extend through vias  216  in a substrate  218  of the interconnect assembly  212 . The contacts  214  include first and second portions  220 ,  222  that are arranged on first and second surfaces  224 ,  226 , respectively, of the substrate  218 . The first and second portions  220 ,  222  mate with the mating elements  20 ,  24  of the electrical components  14 ,  16 , respectively. The contacts  214  provide direct paths through the interconnect assembly  212  for interconnecting the electrical components  14 ,  16 , as opposed to the indirect paths provided by the conductive traces  48  between the contacts  34  and the solder balls  36  of the interconnect assembly  12 . 
     The contacts  214  include first and second beams  230 ,  232  and a post  234  extending therebetween. An intersection is defined by the post  234  and the beams  230 ,  232 , where the beams  230 ,  232  are angled from the post  234  at the intersection. The beams  230 ,  232  have lengths  236 ,  238 . The lengths  236 ,  238  may be substantially equal, such as in the illustrated embodiment, or alternatively, may be different from one another. The beams  230 ,  232  have mating ends  240 ,  242  generally opposite the post  234 . The inward curving portion of the beams  230 ,  232  beyond the mating interfaces  244 ,  246  may be immaterial to the effective length and to how high the beam  230 ,  232  extends above the substrate  218 . The inward curving portion of the beams  230 ,  232  may be excluded or removed from the beams  230 ,  232  in alternative embodiments. 
     In the illustrated embodiment, two different subsets of contacts  214  are illustrated. For example,  FIG. 9  illustrates primary contacts  250  and secondary contacts  252 . One of the differences between the primary contacts  250  and the secondary contacts  252  is that the primary contacts  250  define a mating interface  244 ,  246  that is further from the surfaces  224 ,  226  of the substrate  218 . The primary contacts  250  engage corresponding mating elements  20 ,  24  of the electrical components  14 ,  16  prior to the secondary contacts  252  engaging corresponding mating elements  20 ,  24  of the electrical components  14 ,  16 . The primary contacts make initial contact because the mating ends  240 ,  242  of the primary contacts  250  extend to a point further away from the surfaces  224 ,  226 . The primary contacts  250  make initial engagement with the mating elements  20 ,  24  and the secondary contacts  252  make subsequent engagement with the mating elements  20 ,  24 . By controlling the length and/or the angle of the beams  230 ,  232 , the distance of the mating ends  240 ,  242  from the surfaces  224 ,  226  may be controlled to provide opposed compressible interfaces that sequentially mate with the electrical components  14 ,  16 . In an alternative embodiment, only the first portion  220  or the second portion  222  may have a sequentially mated interface, while the other portion has a single mating interface where all of the contacts mate simultaneously. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments, and are by no means limiting and are merely exemplary embodiments. Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means—plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.