Patent Document

FIELD OF THE INVENTION 
     This invention relates generally to semiconductor manufacture, and more particularly to an improved semiconductor component, and to a method for fabricating the component. 
     BACKGROUND OF THE INVENTION 
     Semiconductor components, such as packages, dice and wafers can include terminal contacts, such as contact balls, contact bumps or contact pins. The terminal contacts are in electrical communication with integrated circuits, and other electrical elements, contained on the components. For some components, such as chip scale packages and BGA packages, the terminal contacts can be arranged in a dense grid array, such as a ball grid array (BGA), or a fine ball grid array (FBGA). The terminal contacts provide an input/output capability for a component, and permit the component to be surface mounted to a supporting substrate, such as a printed circuit board (PCB). 
     FIG. 1A illustrates a prior art semiconductor component  10  having an array of terminal contacts  12  in the form of contact balls. In this example, the component  10  comprises a semiconductor package, such as a chip scale package, a BGA package, or a FBGA package, having a board-on-chip (BOC) configuration. The terminal contacts  12  are typically formed of a solder alloy such as 95%Pb/5%Sn, 60%Pb/40%Sn, 63%Sn/37%Pb, or 62%Pb/36%Sn/2%Ag. Typically, the terminal contacts  12  have the shape of a sphere, a truncated sphere or a hemispherical bump. 
     In addition to the terminal contacts  12 , the component  10  includes an array of bonding pads  14  formed on its backside for attaching the terminal contacts  12  to the component  10 . Typically, the bonding pads  14  comprise a solderable metal such as molybdenum, copper or gold. As shown in FIG. 1D, the component  10  also includes conductors  28 , wire bonding pads  44 , and wire bonds (not shown), that form separate electrical paths between the terminal contacts  12  and the semiconductor die (not shown) contained in the component  10 . In the illustrative embodiment, the component  10  also includes plating conductors  42  that facilitate plating of the bonding pads  14  and the wire bonding pads  38 . The component  10  also includes a solder mask  18  for protecting and electrically insulating the conductors  28  and the terminal contacts  12 . As shown in FIG. 1D, the solder mask  18  includes openings  38  aligned with the bonding pads  14  and with the wire bonding pads  44 . 
     One conventional method for attaching the terminal contacts  12  to the bonding pads  14  uses a solder reflow process. With solder reflow, a layer of eutectic solder is deposited on the bonding pads  14  using a deposition process such as screen printing. A platen can be used to hold the component  10 , while the eutectic solder is deposited on the bonding pads  14 . Prior to depositing the eutectic solder, a flux (not shown) can be applied to the bonding pads  14  for chemically attacking surface oxides, such that the solder can wet the surfaces to be bonded. The flux also performs a tacking function for the terminal contacts  12  prior to solder reflow. Following application of the flux and eutectic solder, the terminal contacts  12  can be placed on the bonding pads  14  in physical contact with the eutectic solder. A fixture can be used to center and maintain the terminal contacts  12  on the bonding pads  14 . 
     Following placement of the terminal contacts  12  on the bonding pads  14 , the component  10  can be placed in a furnace at a temperature sufficient to reflow the eutectic solder and form solder joints  16 . The solder joints  16  metallurgically bond the terminal contacts  12  to the bonding pads  14 . FIG. 1C clearly shows the solder joints  16  and the terminal contacts  12  bonded to the bonding pads  14 . The component  10  can then be removed from the furnace and cooled. As an alternative to a solder reflow performed in a furnace, the bonding process can be performed using a pulse-thermode, a hot-air thermode, or a laser. A solder ball bumper, for example, uses a laser to form the eutectic solder joints  16 , and bond the terminal contacts  12  to the bonding pads  14 . Alternately, the terminal contacts  12  can be bonded to the bonding pads  14  by brazing, by welding, or by application of a conductive adhesive. 
     As shown in FIG. 1A, following the bonding process, the component  10  is typically surface mounted to a supporting substrate  20 , such as a printed circuit board (PCB), a FR-4 card, or a module substrate to form an electronic assembly  22 . For attaching the component  10  to the substrate  20 , additional eutectic solder joints  24  bond the terminal contacts  12  on the component  10  to an array of contact pads  26  on the supporting substrate  20 . A solder reflow process, as previously described, can be used to form the solder joints  24 , and to bond the terminal contacts  12  to the contact pads  26  on the supporting substrate  20 . 
     One factor that can adversely affect the reliability of the assembly  22  during operation in different environments are fatigue failures of the terminal contacts  12  and the bonding pads  14 . Typically, these fatigue failures are induced by thermal expansion mismatches between the component  10  and the supporting substrate  20 . For example, if the component  10  comprises a first material, such as ceramic or plastic having a first CTE, and the supporting substrate  20  comprises a second material, such as FR-4 having a second CTE, cyclic loads can be placed on the terminal contacts  12  and on the bonding pads  14  as the assembly  22  is thermally cycled during operation. As shown in FIG. 1C, the forces acting on the terminal contacts  12  and on the bonding pads  14  include tensile forces  31 T, moment forces  31 M and shear forces  31 S. 
     These forces acting on the terminal contacts  12  and on the bonding pads  14  can also occur during testing of the component following the fabrication process. In particular, semiconductor manufacturers routinely test the components by placement on test boards having sockets for holding the component  10 . During these tests the component  10  can be subjected to temperature cycling. As the socket and component  10  typically have different CTEs, cyclic loads as described above, can be placed on the terminal contacts  12  and on the bonding pads  14 . 
     One aspect of the fatigue failures is that some of the terminal contacts  12  and bonding pads  14  are much more likely to fail because they experience the highest loads. FIG. 1B illustrates this phenomena. In FIG. 1B, the relative displacement of the terminal contacts  12  in the X direction is plotted on the left hand Y axis. Nominal shear strain experienced by the terminal contacts  12  is plotted on the right hand Y axis. Also in FIG. 1B, the terminal contacts  12  have been labeled A 1 -J 1  on the X axis. The inner row adjacent to the A 1 -J 1  row would be the A 2 -J 2  row. 
     Line  30  of FIG. 1B represents nominal shear strain on the terminal contacts  12 . Line  32  of FIG. 1B represents relative displacement in the X direction. Line  34  of FIG. 1B represents theoretical displacement were the terminal contacts  12  not soldered to the board  20  (FIG.  1 A). As shown in FIG. 1B, the terminal contacts  12 , and associated bonding pads  14  on the ends of the component  10  (e.g., A 1 , J 1 ), move the most in the X direction, and also experience the highest strain. On the other hand, the terminal contacts  12  in the middle of the component (e.g., E 1 , D 1 , F 1 ), and their associated bonding pads  14 , experience the least movement, and the least amount of strain. FIGS. 1E and 1F illustrate two possible adverse effects of fatigue failures caused by the forces acting on the terminal contacts  12  and on the bonding pads  14 . In FIG. 1E, the bonding pad  14  associated with the A 1  terminal contact  12  has separated from the component  10 . This situation can cause the conductor  28  which is in electrical communication with the A 1  terminal contact  12  to break, preventing signal transmission to and from the A 1  terminal contact  12 . In FIG. 1F, the bonding pad  14  associated with the A 2  terminal contact  12  has separated from the component  10  causing a break  40  in the conductor  28  which is in electrical communication with the A 2  terminal contact  12 . The break  40  can result from the forces placed on the terminal contact  12 , in combination with micro cracks that are introduced during manufacture. The break  40  in the conductor  28  shorts the electrical path, such that signal transmission between the A 2  terminal contact  12  and the die (not shown) is not possible. 
     In view of the foregoing, improved semiconductor components having improved terminal contacts, bonding pads and conductors are needed in the art. The present invention is directed to a semiconductor component in which multiple electrical paths are provided for the terminal contacts, bonding pads and conductors, that are most likely to experience fatigue failures. In addition, the present invention provides a structure that rigidifies and anchors the terminal contacts and bonding pads to the component, such that breaks are less likely to occur. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, an improved semiconductor component, a method for fabricating the component, and an electronic assembly constructed with the component, are provided. The component includes terminal contacts each of which has a primary electrical path for transmitting and receiving signals. In addition, selected terminal contacts on the component have at least one secondary electrical path configured to replace the primary electrical path should it become damaged. 
     In a first embodiment, the component comprises a boardon-chip semiconductor package having terminal contacts in the form of contact balls in a ball grid array. The component also includes a substrate, a semiconductor die wire bonded to the substrate, and an encapsulant encapsulating the die. The substrate includes an array of bonding pads for the terminal contacts, a pattern of primary conductors in electrical communication with the bonding pads, and wire bonding pads in electrical communication with the conductors. The substrate also includes a solder mask covering the conductors, and having openings aligned with the bonding pads and with the wire bonding pads. 
     Selected terminal contacts, such as the terminal contacts on the outer edges or corners of the array, are in electrical communication with secondary conductors configured to provide alternate electrical paths to the selected terminal contacts equivalent to the primary electrical paths. With this arrangement, an alternate electrical path becomes operable should damage occur to a primary conductor due to thermally induced loads or other factors. In addition, the secondary conductors are configured to rigidify and anchor the selected terminal contacts and their bonding pads, such that separation from the substrate during loading is less likely to occur. 
     The method for fabricating the component includes the step of providing the substrate having the bonding pads, the primary conductors in electrical communication with the bonding pads, and the wire bonding pads in electrical communication with the conductors. In addition, the method includes the step of providing secondary electrical conductors in electrical communication with the selected bonding pads. The method also includes the steps of attaching the die to the substrate, wire bonding the die to wire bonding pads, and then bonding the terminal contacts to the bonding pads. 
     The electronic assembly includes one or more components bonded to a supporting substrate, such as a module substrate or a circuit board. The supporting substrate also includes contact pads configured for bonding to the terminal contacts on the components. During use of the electronic assembly, alternate electrical paths&#39; are provided to the selected terminal contacts on the components should damage occur to the primary electrical paths. The alternate electrical paths allow signals to be transmitted to and from the affected terminal contact. 
     In an alternate embodiment of the invention, the component comprises a bumped semiconductor die or a bumped semiconductor wafer. In another alternate embodiment the component comprises a semiconductor package having terminal contacts in the form of contact columns in a column grid array. In each of the alternate embodiments both primary conductors and secondary conductors are provided to selected terminal contacts. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is an enlarged side elevation view illustrating a prior art semiconductor component bonded to a supporting substrate in an electronic assembly; 
     FIG. 1B is graph illustrating relative shear displacement in the X direction, and shear strain plotted as a function of the location of the terminal contacts for the prior art component; 
     FIG. 1C is an enlarged cross sectional view, taken along line  1 C of FIG. 1A, illustrating a single terminal contact on the prior art component; 
     FIG. 1D is an enlarged cross sectional view, taken along line  1 D— 1 D of FIG. 1A, illustrating a pattern of bonding pads and conductors for the terminal contacts on the prior art component; 
     FIG. 1E is an enlarged cross sectional view, taken along line  1 E— 1 E of FIG. 1D, illustrating the A 1  terminal contact on the prior art component; 
     FIG. 1F is an enlarged cross sectional view, taken along line  1 F of FIG. 1D, illustrating a bonding pad and conductor for the A 2  terminal contact on the prior art component; 
     FIG. 2A is an enlarged schematic side elevation view illustrating a semiconductor component, in the form of a semiconductor package, constructed in accordance with the invention; 
     FIG. 2B is an enlarged cross sectional view of the component, taken along line  2 B— 2 B of FIG. 2A; 
     FIG. 2C is an enlarged cross sectional view, taken along line  2 C— 2 C of FIG. 2B, illustrating bonding pads and conductors of the component; 
     FIG. 2D is an enlarged cross sectional view, taken along line  2 D— 2 D of FIG. 2C, illustrating a substrate and solder mask of the component; 
     FIG. 2E is an enlarged cross sectional view, taken along line  2 E— 2 E of FIG. 2C, illustrating a conductor of the component; 
     FIG. 2F is an enlarged cross sectional view, taken along line  2 F— 2 F of FIG. 2C, illustrating a wire bonding pad of the component; 
     FIG. 2G is an enlarged cross sectional view, taken along line  2 G— 2 G of FIG. 2C, illustrating a bonding pad for a terminal contact of the component; 
     FIG. 3A an enlarged plan view of a strip containing multiple substrates suitable for fabricating components in accordance with invention; 
     FIG. 3B is an enlarged bottom view of the strip; 
     FIGS. 4A-4C are schematic cross sectional views illustrating steps in a method for fabricating the component of FIG. 2A; 
     FIG. 5A is a schematic plan view illustrating an electronic assembly fabricated using multiple components constructed in accordance with the invention; 
     FIG. 5B is an enlarged cross sectional view of the assembly, taken along line  5 B— 5 B of FIG. 5A, illustrating a component bonded to a substrate of the assembly; 
     FIG. 5C is an enlarged cross sectional view, taken along line  5 C— 5 C of FIG. 5B, illustrating bonding pads and conductors on the component; 
     FIG. 6A if a plan view illustrating a semiconductor component, in the form of a semiconductor wafer, constructed in accordance with the invention; 
     FIG. 6B is a plan view, taken along line  6 B of FIG. 6A, illustrating a semiconductor component, in the form of a semiconductor die, constructed in accordance with the invention; 
     FIG. 6C is an enlarged cross sectional view, taken along line  6 C— 6 C of FIG. 6B, illustrating a bumped terminal contact on the component; and 
     FIG. 7 is a schematic cross sectional view illustrating a semiconductor component, in the form of a package with pin terminal contacts, constructed in accordance with the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 2A and 2B, a semiconductor component  46  constructed in accordance with the invention is illustrated. As used herein, the term “semiconductor component” refers to an element, or to an assembly, that includes a semiconductor die. In the illustrative embodiment, the component  46  comprises a board-on-chip (BOC) semiconductor package. However, the semiconductor component  46  can comprise another type of semiconductor package such as a chip-on-board (COB) package, a chip scale package (CSP), a BGA device, or a bumped semiconductor die. The semiconductor component can also comprise a semiconductor wafer containing multiple semiconductor dice. 
     The component  46  includes a substrate  50  having a first surface  56  (FIG.  2 B), and an opposing second surface  58  (FIG.  2 B). The first surface  56 , and the second surface  58 , are the major planar surfaces of the substrate  50 . The substrate also includes a wire bonding opening  68  therethrough, extending from the first surface  56  to the second surface  58 . In addition, the substrate  50  includes a pattern of primary conductors  60  (FIG. 2B) formed on the first surface  56 , and a corresponding die attach area  62  formed on the second surface  58 . The substrate  50  also includes a solder mask  64  on the first surface  56 , and a solder mask  66  on the second surface  58 . 
     The substrate  50  comprises an electrically insulating material such as an organic polymer resin reinforced with glass fibers. Suitable materials for the substrate  50  include bismaleimide-triazine (BT), epoxy resins (e.g., “FR-4” and “FR-5”), and polyimide resins. These materials can be formed with a desired thickness, and then punched, machined, or otherwise formed with a required peripheral configuration, and with required features. A representative thickness of the substrate  50  can be from about 0.2 mm to 1.6 mm. 
     In addition to the substrate  50 , the component  46  includes an array of terminal contacts  48  on the substrate  50  in electrical communication with integrated circuits, or other electrical elements contained on the component  46 . The terminal contacts  48  provide separate electrical connection points for transmitting (writing) and receiving (reading) electronic signals from the component  46 . In addition, the terminal contacts  48  provide a structure for bonding the component  46  to a supporting substrate. In the illustrative embodiment, the terminal contacts  48  comprise generally spherically shaped contact balls in a ball grid array (BGA), or a fine ball grid array (FBGA). However, the terminal contacts  48  can comprise other conventional contacts having other shapes, and arranged in other patterns, to provide multiple electrical connection points for the component. By way of example, representative contacts include bumps, columns, studs, domes and cones. Also, the terminal contacts can be made of any electrically conductive material, such as a solder alloy as previously discussed, copper, nickel, or a conductive polymer. 
     As shown in FIG. 2A, the terminal contacts  48  have a diameter “D” and a spacing or pitch “P”. With the terminal contacts  48  comprising contact balls in a ball grid array, or a fine ball grid array, a representative range for the diameter D can be from about 0.127 mm (0.005 inch) to 0.762 mm (0.030 inch). A representative range for the pitch P can be from about 0.228 mm (0.008 inch) to 2.0 mm (0.078 inch), For convenience, the terminal contacts  48  are labeled with a letter and a numeral (A 1 -J 1 ) that indicate their location in the grid array. 
     As shown in FIG. 2B, the component  46  also includes a semiconductor die  52 , and a die encapsulant  54  on the die  52  and on the second surface  58  of the substrate  50 . The die  52  includes a row of bond pads  70  formed on a face portion thereof, in electrical communication with the integrated circuits contained in the die  52 . The die  52  is bonded face down to the die attach area  62  of the substrate  50  with the bond pads  70  on the die  52  aligned with the bonding opening  68  in the substrate  50 . 
     An adhesive layer  72  bonds the die  52  to die attach area  62  of the substrate  50 . The adhesive layer  72  can comprise a filled epoxy, an unfilled epoxy, an acrylic, a polyimide or an adhesive tape material. In addition, wires  74  are placed through the wire bonding opening  68  in the substrate  50  and are wire bonded to the bond pads  70  on the die  52 , and to corresponding wire bonding pads  76  (FIG. 2C) on the substrate  50 . A wire bond encapsulant  78  fills the wire bonding opening  68  and encapsulates the wires  74 . The wire bond encapsulant  78  can comprise a glob top polymer material, such as epoxy or silicone, deposited in a desired shape using a suitable process such as dispensing through a nozzle. The encapsulant  54  can comprise a Novolac based epoxy formed in a desired shape using a transfer molding process, and then cured using an oven. 
     Referring to FIG. 2C, the component  46  (FIG. 2A) also includes bonding pads  80  on the substrate  50  for bonding the terminal contacts  48  to the substrate  50 . The bonding pads  80  are in electrical communication with the primary conductors  60  and the wire bonding pads  76 . In addition, the bonding pads  60  are in electrical communication with plating conductors  60 P on the substrate  50  that extend to an edge of the substrate  50 . The plating conductors  60 P are initially connected to plating buses  82 , which are used to apply a current to the bonding pads  80  and to the wire bonding pads  76  for plating a non-oxidizing metal layer  84  (FIGS. 2F and 2G) such as gold on the bonding pads  80  and the wire bonding pads  76 . As shown in FIGS. 2D and 2E, the solder mask  64  covers the substrate  50  and the conductors  60 . However, as shown in FIGS. 2F and 2G, the solder mask  64  includes openings  86  aligned with the bonding Dads  20  and the wire bonding pads  76 . 
     As also shown in FIG. 2C, selected bonding pads  80 - 1  on the ends of the array include secondary conductors  60 - 1 . These secondary conductors  60 - 1  provide alternate electrical paths for the selected bonding pads  80 - 1  should the conductors  60  break as previously described. In addition, the secondary conductors  60 - 1  help to anchor the selected bonding pads  80 - 1  and associated terminal contacts  48  to the substrate  50 . 
     As shown in FIG. 2C, the secondary conductor  60 - 1  is attached to the bonding pad  80 - 1  at a connection point  81  which is about 180° from a connection point  83  of the primary conductor  60  to the bonding pad  80 - 1 . In addition, the secondary conductor  60 - 1  makes about a 90° angle to intersect with the plating conductor  60 P for the bonding pad  80 - 1  at connection point  85 . The secondary conductor  60 - 1  then extends along a periphery of the bonding pad  80 - 1  generally parallel to the primary conductors  60 , then makes about a 90° turn to intersect with the primary conductor  60  for the bonding pad  80 - 1  at a connection point  87 . The connection point  87  of the secondary conductor  60 - 1  with the primary conductor  60  is well past the connection point  83  at which the primary conductor  60  connects to the bonding pad  80 - 1 . As the primary conductor  60  is most likely to break at connection point  83  the secondary conductor  60 - 1  provides an alternate path around the likely breaking point. 
     As also shown in FIG. 2C, other selected bonding pads  80 - 2  on the outside corners of the array include multiple secondary conductors  60 - 2 ,  60 - 3 . In particular, the selected bonding pads  80 - 2  each includes two secondary conductors  602 ,  60 - 3 . Again, the secondary conductors  60 - 2 ,  60 - 3  provide alternate electrical paths, and help to anchor the selected bonding pads  80 - 1 ,  80 - 2  and associated terminal contacts  48  to the substrate  50 . 
     As also shown in FIG. 2C, secondary conductor  60 - 3  has a connection point  89  with the bonding pad  80 - 2  proximate to the plating conductor  60 P. In addition, secondary conductor  60 - 3  has a connection point  93  with the primary conductor  60  for the bonding pad  80 - 2 . Again the connection points  91 ,  93  are located to provide an alternate electrical path around a connection point  95  of the bonding pad  80 - 2  with the primary conductor  60 . Secondary conductor  60 - 2  has two connection points with the bonding pad  80 - 2  including a first connection point  89  proximate to the plating conductor  60 P, and a second connection point  97  about 90° from the plating conductor  60 P. 
     Referring to FIGS. 3A and 3B, the substrate  50  can initially comprise a segment of a panel  88 . The panel  88  is similar in function to a semiconductor lead frame, and includes multiple substrates  50  permitting the fabrication of multiple components  46  (FIG. 2A) at the same time. The panel  88  includes circular indexing openings  90  proximate to the longitudinal edges thereof. The indexing openings  90  permit the panel  88  to be handled by automated transfer mechanisms associated with chip bonders, wire bonders, molds, and trim machinery. In addition, the panel  88  includes elongated separation openings  92  which facilitate singulation of the substrates  50  on the panel  88  into separate components  46  (FIG.  2 A). The plating buses  82  for the plating conductors  60 P are located proximate to the separation openings  92 , and are severed during singulation of the substrates  50 . 
     The primary conductors  60 , secondary conductors  60 - 1 ,  60 - 2 ,  60 - 3 , plating conductors  60 P, bonding pads  80  and wire bonding pads  76  can comprise a highly conductive metal layer, which is blanket deposited onto the panel  88  (e.g., electroless or electrolytic plating), and then etched in required patterns. Alternately, an additive process, such as electroless deposition through a mask, can be used. Suitable metals include copper, aluminum, titanium, tungsten, tantalum, platinum, molybdenum, cobalt, nickel, gold, and iridium. If desired, the panel  88  can be constructed from a commercially produced bi-material core, such as a copper clad bismaleimide-triazine (BT) core, available from Mitsubishi Gas Chemical Corp., Japan. A representative weight of the copper can be from 0.5 oz to 2 oz. per square foot. 
     As also shown in FIGS. 3A and 3B, the panel  88  also includes triangular metal segments  94 , and circular metal segments  96  for each substrate  50 . The metal segments  94 ,  96  can comprise a same metal as the conductors  60 . The triangular metal segments  94  function as pin # 1  indicators. The circular metal segments  96  function as alignment fiducials. 
     Referring to FIGS. 4A-4C, steps in a method for fabricating the component  46  are illustrated. Although these steps are shown as being performed on a single substrate  50 , it is to be understood that the steps are performed on each of the substrates  50  contained on the panel  88 , substantially at the same time. Initially, as shown in FIG. 4A, the substrate  50  can be provided with the primary conductors  60 , the secondary conductors  60 - 1 ,  60 - 2 ,  60 - 3 , the plating conductors  60 P, the bonding pads  80  and the wire bonding pads  76 . In addition, the die attach area  62  can include the wire bonding opening  68  formed through the substrate  50 . 
     As also shown in FIG. 4A, the solder masks  64 ,  66  can be formed by blanket depositing, exposing and then patterning a photoimageable dielectric material, such as a negative or positive tone resist. The solder mask  64  on the first surface  56  of the substrate  50  includes openings  86  aligned with the bonding pads  80  and the wire bonding pads  76 . The solder mask  66  on the second surface  58  of the substrate  50  includes an opening  69  having an outline that is slightly larger than the outline of the semiconductor die  52 . One suitable resist is commercially available from Taiyo America, Inc., Carson City, Nev., under the trademark “PSR-4000”. The “PSR-4000” resist can be mixed with an epoxy such as epoxy “ 720 ” manufactured by Ciba-Geigy (e.g., 80% PSR-4000 and 20% epoxy “720”). Another suitable resist is commercially available from Shipley under the trademark “XP-9500”. Following forming of the solder masks  64 ,  66  the bonding pads  80  and the wire bonding pads  76  can be plated with the nonoxidizing layers  84  (FIGS. 2F and 2G) using the plating bus  82  (FIG.  3 A), and electrolytic deposition of a nonoxidizing metal (e.g., gold) through the openings  86  in the solder mask  64 . 
     Next, as shown in FIG. 4B, the die  52  can be bonded to the substrate  50  using the adhesive layer  72 . A conventional die attacher can be used to form the adhesive layer  72  and adhesively bond the die  52  to the substrate  50 . As also shown in FIG. 4B, following attachment of the die  52  to the substrate  50 , the wires  74  can be wire bonded to the wire bonding pads  76 , and to the bond pads  70  on the die  52 . A conventional wire bonder can be used to perform the wire bonding step. Although in the illustrative embodiment, the die  52  is mounted face down to the substrate  50 , the die  52  can alternately be back bonded to the substrate  50 , and wire bonded to conductors located on a same surface of the substrate  50  as the die  52 . As an alternative to wire bonding, a flip chip process (e.g., C 4 ), or a TAB bonding process, can be used to electrically connect the die  52  to the conductors  60 . 
     Next as shown in FIG. 4C, following wire bonding, the die encapsulant  54  can be formed on the die  52  and on the substrate  50 . The die encapsulant  54  can comprise a Novolac based epoxy formed in a desired shape using a transfer molding process, and then cured using an oven. Also, if desired, the wire bond encapsulant  78  can be formed on the wires  74 . 
     As also shown in FIG. 4C, following formation of the die encapsulant  54 , the terminal contacts  48  can be bonded to the bonding pads  80 . If the terminal contacts  48  comprise solder, a solder reflow process can be employed. Prior to the solder reflow process, solder flux can be deposited on the bonding pads  80  and on the terminal contacts  48 . The terminal contacts  48  can then be placed on the bonding pads  80 , and a furnace used to form metallurgical solder joints  116  between the terminal contacts  48  and the bonding pads  80 . 
     Referring to FIGS. 5A-5C, an electronic assembly  98  constructed in accordance with the invention is illustrated, The electronic assembly  98  includes a supporting substrate  100  and a plurality of the semiconductor components  46  mounted to the supporting substrate  100 . In the illustrative embodiment the assembly  98  is in the form of a multi chip module, such as a SIMM or DIMM memory module. However, it is to be understood that the semiconductor component  46  can be used to construct other types of electronic assemblies such as circuit boards, card assemblies, and ball grid array assemblies. 
     The supporting substrate  100  includes an electrical connector  102 , such as an edge connector, and a pattern of conductors  106  in electrical communication with the electrical connector  102 . The supporting substrate  100  also includes an array of contact pads  104  (FIG. 5B) having a pattern matching that of the terminal contacts  48  on the components  46 . The contact pads  104  are in electrical communication with the conductors  106  and with the electrical connector  102 . The terminal contacts  48  on the components  46  are bonded to the contact pads  104  substantially as previously described using solder joints  118  (FIG.  5 B). 
     As shown in FIG. 5C, during operation of the assembly  58  alternate electrical paths are provided for selected bonding pads  80 - 1 ,  80 - 2  should the primary conductors  60  associated with these bonding pads  80 - 1 ,  80 - 2  become damaged. In the illustrative embodiment, alternate electrical paths are provided by the secondary conductor for the bonding pads subject to the highest loads from thermal cycling (e.g., end pads and corner pads of the array). However, it is to be understood that alternate electrical paths can be provided for any or all of the bonding pads of the array. 
     As shown in FIG. 5C, a break  108  has formed between the primary conductor  60  associated with bonding pad  80 - 1 . However, an alternate electrical path, as indicated by arrows  112 , is provided by secondary conductor  60 - 1 . Similarly, a break  110  has formed between the primary conductor  60  associated with bonding pad  80 - 2 . However, two alternate electrical paths, as indicated by arrows  114 , are provided by secondary conductors  60 - 2  and  60 - 3 . In addition, to providing alternate electrical paths, the secondary conductors  60 - 1 ,  60 - 2 ,  60 - 3  help to anchor the bonding pads  80 - 1 ,  80 - 2  to the substrate  50 , such that the breaks  108 ,  110  are less likely to occur. 
     Referring to FIGS. 6A-6C and FIG. 7, alternate embodiment components constructed in accordance with the invention are illustrated. In FIG. 6A, a component  46 W comprises a semiconductor wafer containing a plurality of bumped semiconductor dice  46 D. As shown in FIG. 6B, each die  46 D, following singulation from the wafer, can also be considered a component. 
     As shown in FIG. 6C, each die  46 D includes a semiconductor substrate  119 , bond pads  120  on the substrate  119  in electrical communication with the integrated circuits in the substrate  119 , and bumped terminal contacts  48 B on the bond pads  120 . In this embodiment, the bumped terminal contacts  48 B can comprise contact bumps formed on the bond pads  120  using a deposition process, such as evaporation of a ball limiting metallurgy (BLM) and solder material through openings in a metal mask. In addition to the bumped terminal contacts  48 B, the ball limiting metallurgy (BLM) can include a multi layered stack (not shown) such as an adherence layer (e.g., Cr), a solderable layer (e.g., Cu) and a flash layer (e.g., Au). This process is also known as C 4  technology, and is typically used to deposit bumped terminal contacts  46 B directly onto bond pads  120  made of aluminum Alternately, other deposition processes, such as electroless deposition, or electrolytic deposition can be used to form the bumped terminal contacts  48 B. 
     As shown in FIG. 7, a component  46 C, such as a semiconductor package, includes a bond pad  122  and a column terminal contact  48 C bonded to the bond pad  122  using a Ad solder fillet  124 . This type of component  46 C is sometimes referred to as a ceramic column grid array (CCGA). The column terminal contact  4 RC comprises an elongated contact column configured for bonding to a corresponding contact pad on a supporting substrate substantially as previously described. 
     In each of the alternate embodiment components  46 W,  46 D or  46 C, secondary electrical conductors can be provided for selected terminal contacts  48 B,  48 C substantially as previously described. In addition, the secondary electrical conductors function substantially as previously described to provide alternate electrical paths should the primary conductors in electrical communication with the bond pads  120 ,  124  become damaged. 
     Thus the invention provides an improved semiconductor component, a method for fabricating the component, and an electronic assembly constructed using the component. The component includes terminal contacts having multiple electrical conductors that provide alternate electrical paths and a rigidifying structure. While the invention has been described with reference to certain preferred embodiments, as will be apparent to those skilled in the art, certain changes and modifications can be made without departing from the scope of the invention as defined by the following claims.

Technology Category: h