Abstract:
In one embodiment, a method for assembling a ball grid array (BGA) package is provided. The method includes providing a stiffener that has opposing first and second surfaces, wherein the first surface is capable of mounting an integrated circuit (IC) die in a central area and forming a pattern in at least a portion of the first surface to enhance the adhesiveness of an encapsulant material to the first surface.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 12/619,385, filed Nov. 16, 2009 (now U.S. Pat. No. 8,039,949), which is a divisional of U.S. application Ser. No. 10/963,620, filed Oct. 14, 2004 (now U.S. Pat. No. 7,629,681), which is a divisional of U.S. application Ser. No. 09/997,272, filed Nov. 30, 2001 (now U.S. Pat. No. 6,882,042), which claims the benefit of U.S. Provisional Application No. 60/250,950, filed Dec. 1, 2000, all of which are incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Field 
     The invention relates generally to the field of integrated circuit (IC) device packaging technology, and more particularly to substrate stiffening and heat spreading techniques in ball grid array (BGA) packages. 
     2. Background Art 
     Integrated circuit (IC) dies are typically mounted in or on a package that is attached to a printed circuit board (PCB). One such type of IC die package is a ball grid array (BGA) package. BGA packages provide for smaller footprints than many other package solutions available today. A BGA package has an array of solder balls located on a bottom external surface of a package substrate. The solder balls are reflowed to attach the package to the PCB. The IC die is mounted to a top surface of the package substrate. Wire bonds typically couple signals in the IC die to the substrate. The substrate has internal routing which electrically couples the IC die signals to the solder balls on the bottom substrate surface. 
     It would be advantageous to provide a thermally and electrically enhanced ball grid array (BGA) package that is smaller, cheaper, customizable and capable of superior performance when compared with conventional BGA packages. More specifically, it would be advantageous to provide an advanced BGA package that achieves: 1) enhanced thermal and electrical performance; 2) reduced package size; 3) increased flexibility of die configuration; 4) reduced ball pitch; 5) increased flexibility in circuit routing density; and 6) configurations with greater thermal spreading capabilities. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. 
         FIG. 1  is a cross-sectional representation of a BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 2  is a cross-sectional representation of another BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 3  is a cross-sectional representation of another BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 4  is a cross-sectional representation of another BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 5  is a cross-sectional representation of another BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 6  is a cross-sectional representation of another BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 7  is a cross-sectional representation of another BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 8  is a cross-sectional representation of another BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 9  is a cross-sectional representation of another BOA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 10  is a cross-sectional representation of another BOA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 11  is a cross-sectional representation of another BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 12  is a cross-sectional representation of another BOA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 13  is a cross-sectional representation of another BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 14  is a cross-sectional representation of another BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 15  is a cross-sectional representation of another BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 16  is a cross-sectional representation of another BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 17  is a cross-sectional representation of another BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 18  is a cross-sectional representation of another BGA package design in accordance with one embodiment of the disclosed method and apparatus. 
     
    
    
     The present invention will now be described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears. 
     DETAILED DESCRIPTION 
     The present invention provides a thermally and electrically enhanced ball grid array (BGA) packaging that is smaller, cheaper, customizable and capable of superior performance when compared with conventional BGA packages. More specifically, the present invention offers advanced BGA packages that achieve: 1) enhanced thermal and electrical performance; 2) reduced package size; 3) increased flexibility of die configuration; 4) reduced ball pitch; 5) increased flexibility in circuit routing density; and 6) optional configurations with or without the attachment of a heat sink. 
     Embodiments of the present invention may be used in a variety of electronic devices, including telecommunication devices, mobile phones, camcorders, digital cameras, network systems, printers, and testers. 
     Advantages of the various embodiments of the invention include: 1) an embedded heat spreader in the package for the silicon die to adhere onto, and a connection between the die and the heat spreader to provide thermal and electrical performance enhancement; 2) an option of a fully populated ball grid array assignment for circuit routing; 3) an option of multi-layer heat spreader structure to provide split and isolated ground; 4) an option of utilizing single, double or multi-layer metal circuitry substrate with or without plating traces and with or without conductive via connections to accommodate different thermal, electrical and design requirements; 5) exposed die attach pad for enhanced thermal performance; 6) drop-in heat slug for direct thermal and electrical conduction; 7) flexible range of ball pitch from 0.3 mm to 1.5 mm; 8) active ground connection capability from silicon die to motherboard through conductive slug attachment or through solder ball connects to the heat spreader; 9) high thermal conductive path; 10) low package profile compared with plastic ball grid array (PBGA) and other conventional BGA packages; and 11) wafer saw or punch format for maximized material utilization. 
     Embodiments of the present invention are described in detail below, and are designated as Designs 1 through 18. 
     Design 1—Fully Populated Package with Solid Grounding 
       FIG. 1  shows a BGA package  100 , according to an embodiment of the present invention. BGA package  100  incorporates a substrate  130  with a single metal layer, and a heat spreader/stiffener  112  with selective plating. BGA package  100  includes substrate  130 , stiffener  112 , an integrated circuit die  114 , a mold/glob top  120 , a plurality of solder balls  122 , a first wire connection  124 , and a second wire connection  126 . 
     Substrate  130  includes a base material/dielectric layer  102 , a conductive metal layer  106 , and a circuit mask  108 . Metal layer  106  is attached to the bottom surface of dielectric layer  102  by an adhesive  104 . Metal layer  106  is a conductive layer that is patterned with traces. Circuit mask  108  is applied to the top surface of dielectric layer  102 . Dielectric layer  102  may be any one of PCB, FR4, polyimide, and ceramic dielectric materials. 
     Stiffener  112  is attached to the top surface of substrate  130  by an adhesive  110 . Die  114  is attached to the top surface of stiffener  112  by a die attach epoxy  116 . First wire connection  124  is coupled from a pin on die  114  to stiffener  112 . A bondable plating surface  118  is formed on the top surface of stiffener  112  to enhance attachment of first wire connection  124  to stiffener  112 . Second wire connection  126  is coupled from a pin on die  114  to a trace of metal layer  106 . Mold/glob top  120  is formed over the top surface of stiffener  112  to encapsulate die  114  and first and second wire connections  124  and  126 . 
     Preferably, copper is used to make metal layer  106 , although other metals may also be used. Similarly, stiffener  112  is preferably made from copper so that it may provide a substantially rigid and planar surface, enhance the coplanarity of the different layers of substrate  130 , and, at the same time, act as a heat spreader to help dissipate heat. Alternatively, other materials, such as aluminum or ceramic, may also be used to make the stiffener. 
     Preferably, bondable surface  118  is selectively plated, chemically deposited or electro-deposited on stiffener  112  for solid or float grounding purposes. Otherwise, stiffener  112  may be fully plated. Dielectric layer  102 , preferably a polyimide tape, is patterned with openings or vias for accepting solder balls  122  so that solder balls  122  make electrical contact with the patterned conductive metal layer  106 . The distance between centers of adjacent solder balls  122  is shown as ball pitch  128  in  FIG. 1 . 
     Table 1 shows example dimensions and ranges for some of the elements shown in  FIG. 1 : 
                             TABLE 1                   Element   Thickness (mm)                       Base material/dielectric layer 102   0.025-2             Adhesive 104   0.012-0.25           Trace/Metal layer 106   0.012-0.35           Circuit mask 108   0.017-0.20           Adhesive 110   0.012-0.25           Stiffener 112   0.1-1            Thickness of die 114   0.15-0.8           Die attach Epoxy 116    0.025-0.075           Bondable plating surface 118   0.0005-0.05            Mold/Glob top 120   0.3-3            Solder ball 122   0.15-0.9               (collapsed height)           Ball pitch 128    0.3-1.5                    
Design 2—Fully Populated Package with Solid Grounding
 
       FIG. 2  shows a BGA package  200 , according to an embodiment of the present invention. As shown in  FIG. 2 , BGA package  200  is basically the same as BGA package  100 , except that it does not have an adhesive layer  104  between patterned dielectric layer  102  and patterned conductive metal layer  106 . Furthermore, a first and second dimple design  202  and  204  are shown on stiffener  112  in  FIG. 2 . First and/or second dimple designs  202  and  204  on stiffener  112  (e.g., a protrusion or indention) are preferably introduced to enhance the adhesiveness of the molding compound or encapsulant material (i.e., mold/glob top  120 ) to the surface of stiffener  112  by increasing the total contact surface area. First and second dimple designs  202  and  204  may have any applicable dimensions. 
     Design 3—Fully Populated Package with Two Stiffeners and Symmetrical Segment Grounding 
       FIG. 3  shows a BGA package  300 , according to an embodiment of the present invention. As shown in  FIG. 3 , BGA package  300  incorporates first stiffener  112  and a second stiffener  302 , each with selective plating, to achieve split grounding. In BGA package  300 , die  114  is mounted to the top surface of second stiffener  302 . A third wire connection  306  is coupled from a pin on die  114  to bondable plating surface  118  on second stiffener  302 . In an example embodiment, bondable plating surface  118  on the top stiffener, second stiffener  302 , may be used for digital grounding, and bondable plating surface  118  on the bottom stiffener, first stiffener  112 , may be used for analog grounding. A dielectric adhesive layer  304  is incorporated between first and second stiffeners  112  and  302  to ensure separated grounding. 
     Other features of BGA package  300  are similar to the corresponding features in BGA package  200 . 
     Design 4—Fully Populated Package with Two Stiffeners and Asymmetrical Segment Grounding 
       FIG. 4  shows a BGA package  400 , according to an embodiment of the present invention. As shown in  FIG. 4 , BGA package  400  is similar to BGA package  300  shown in  FIG. 3 , except that split solid grounding is done asymmetrically. In other words, bondable plating surfaces  118  are placed on the respective first and second stiffeners  112  and  302  asymmetrically. 
     Other features of BGA package  400  are similar to the corresponding features in aforementioned designs. 
     Design 5—Fully Populated Package with Enhanced Routability 
       FIG. 5  shows a BGA package  500 , according to an embodiment of the present invention. As shown in  FIG. 5 , a substrate  502  of BGA package  500  incorporates two conductive layers, first metal layer  106  and second metal layer  504 , that include traces. First circuit mask  108  is formed over the top surface of substrate  502 , and a second circuit mask  506  is formed over the bottom surface of substrate  502 . First and second metal layer  106  and  504  are separated by dielectric layer  102 , which is preferably a polyimide tape. Dielectric layer  102  includes selective conductive vias  508  between first and second metal layers  106  and  504 . By selectively connecting the metal layers through conductive vias  508 , enhanced routing flexibility as well as enhanced electrical and thermal performance is provided. 
     Other features of BGA package  500  are similar to the corresponding features in aforementioned designs. 
     Design 6—Fully Populated Package with Enhanced Routability 
       FIG. 6  shows a BGA package  600 , according to an embodiment of the present invention. As shown in  FIG. 6 , BGA package  600  is similar to BGA package  500  shown in  FIG. 5  except that BGA package  600  includes a substrate  616  that has four conductive trace layers: a first metal layer  602 , a second metal layer  604 , a third metal layer  606 , and a fourth metal layer  608 . The metal layers are separated by dielectric layers with conductive vias. A first dielectric layer  610  separates first metal layer  602  and second metal layer  604 . A second dielectric layer  612  separates second metal layer  605  and third metal layer  606 . A third dielectric layer  614  separates third metal layer  606  and fourth metal layer  608 . For example, second dielectric layer  612  may be a prepeg organic material. Solder balls  122  are attached to portions of fourth metal layer  608  exposed through second circuit mask  506 . 
     As such, BGA package  600  provides superior routing flexibility to BGA package  500 , and offers excellent electrical and thermal performance. Note that more conductive layers may be used. In that case, however, both the manufacturing cost and the package size (thickness) would increase accordingly. 
     Other features of BGA package  600  are similar to the corresponding features in aforementioned designs. 
     Design 7—Fully Populated Package with Enhanced Signal Integrity 
       FIG. 7  shows a BGA package  700 , according to an embodiment of the present invention. As shown in  FIG. 7 , BGA package  700  uses conductive paths  702  to connect and ground selected solder balls  122  to stiffener  112 . As such, BGA package  700  provides enhanced noise reduction, thus improved signal integrity, by grounding the discharge current through the ground bond (i.e., wire connection  124 ), stiffener  112 , conductive paths  702 , and solder balls  122 , and discharge to a connecting motherboard (not shown). 
     Other features of BGA package  700  are similar to the corresponding features in aforementioned designs. 
     Design 8—Fully Populated Package with Enhanced Signal Integrity and Routability 
       FIG. 8  shows a BGA package  800 , according to an embodiment of the present invention. As shown in  FIG. 8 , BGA package  800  is basically a combination of BGA package  500  shown in  FIG. 5  and BGA package  700  shown in  FIG. 7 , providing enhanced routing flexibility and signal integrity. In other words, BGA package  800  is BGA package  700  with two conductive layers, first and second metal layers  106  and  504 , instead of a single metal layer. 
     Other features of BGA package  800  are similar to the corresponding features in aforementioned designs. 
     Design 9—Partially Depopulated Package with Partially Exposed Stiffener 
       FIG. 9  shows a BGA package  900 , according to an embodiment of the present invention. As shown in  FIG. 9 , substrate  130  of BGA package  900  has a “punched” opening or window that exposes a part of stiffener  112 , shown as exposed stiffener portion  902 . BGA package  900  improves thermal performance because heat may be readily dissipated via exposed stiffener portion  902  of stiffener  112 . In addition, plating trace routability is also enhanced through the debussing window punched opening. It should be readily apparent to those of ordinary skill in the art that the size of the opening may vary depending on, for example, the desired size of an optional heat slug to be attached to stiffener  112  via the opening (as described in embodiments in the sections below related to Designs 11-14). 
     Other features of BGA package  900  are similar to the corresponding features in aforementioned designs. 
     Design 10—Partially Depopulated Package with Partially Exposed Stiffener 
       FIG. 10  shows a BGA package  1000 , according to an embodiment of the present invention. As shown in  FIG. 10 , BGA package  1000  is similar to BGA package  900  shown in  FIG. 9 , except that BGA package includes substrate  502 , which has two patterned conductive layers (first and second metal layers  106  and  504 ), instead of one metal layer, for enhanced routing flexibility. Substrate  502  has a punched opening or window, similar to that shown in substrate  130  in  FIG. 9 . 
     Other features of BGA package  1000  are similar to the corresponding features in aforementioned designs. 
     Design 11—Partially Depopulated Package with Drop-in Heat Slug 
       FIG. 11  shows a BGA package  1100 , according to an embodiment of the present invention. As shown in  FIG. 11 , BGA package  1100  is similar to BGA package  900  shown in  FIG. 9 , but with an additional drop-in heat slug  1102  attached to the bottom surface of stiffener  112  by adhesive  1104 . Adhesive  1104  is a conductive adhesive, epoxy, or solder. Heat slug  1102  allows direct conductive heat dissipation from die  114  through die attach epoxy  116 , stiffener  112 , adhesive  1104 , and heat slug  1102  to an attached motherboard (not shown). 
     Other features of BGA package  1100  are similar to the corresponding features in aforementioned designs. 
     Design 12—Partially Depopulated Package with Drop-in Heat Slug 
       FIG. 12  shows a BGA package  1200 , according to an embodiment of the present invention. As shown in  FIG. 12 , BGA package  1200  is similar to BGA package  1000  shown in  FIG. 10 , but with the addition of drop-in heat slug  1102 . Heat slug  1102  allows direct conductive heat dissipation from the die  114  through die attach epoxy  116 , stiffener  112 , adhesive  1104 , and heat slug  1102  to an attached motherboard (not shown). 
     Other features of BGA package  1200  are similar to the corresponding features in aforementioned designs. 
     Design 13—Partially Depopulated Package with Drop-in Heat Slug 
       FIG. 13  shows a BGA package  1300 , according to an embodiment of the present invention. As shown in  FIG. 13 , BGA package  1300  is similar to BGA package  1100  shown in  FIG. 11 . The difference is that BGA package  1300  has an added locking mechanism for attaching drop-in heat slug  1102  to stiffener  112 . The locking mechanism includes a bump  1302  on heat slug  1102  that fits into a slot  1304  in stiffener  112 . The locking mechanism allows easy attachment and alignment of heat slug  1102  to stiffener  112 . An adhesive  1306  is used to adhere bump  1302  in slot  1304 . Adhesive  1306  may be a conductive adhesive, epoxy, or solder. 
     Other features of BGA package  1300  are similar to the corresponding features in aforementioned designs. 
     Design 14—Partially Depopulated Package with Drop-in Heat Slug 
       FIG. 14  shows a BGA package  1400 , according to an embodiment of the present invention. As shown in  FIG. 14 , BGA package  1400  is similar to BGA package  1300  shown in  FIG. 13 , except it includes a substrate  502  that has two conductive layers (first and second metal layers  106  and  504 ) instead of a single conductive layer. 
     Other features of BGA package  1400  are similar to the corresponding features in aforementioned designs. 
     Design 15—Partially Depopulated Package with Partially Exposed Down-Set Stiffener 
       FIG. 15  shows a BGA package  1500 , according to an embodiment of the present invention. As shown in  FIG. 15 , BGA package  1500  has a stiffener  112  with a lowered and exposed stiffener portion  1502 . This “down-set” stiffener portion  1502  provides for a thinner package design. For example, as shown in  FIG. 15 , die  114  can sit lower in BGA package  1500  than in other BGA packages. The exposed stiffener  112  also enhances thermal performance similar to BGA package  900  shown in  FIG. 9 . 
     Other features of BGA package  1500  are similar to the corresponding features in aforementioned designs. 
     Design 16—Partially Depopulated Package with Partially Exposed Down-Set Stiffener 
       FIG. 16  shows a BGA package  1600 , according to an embodiment of the present invention. As shown in  FIG. 16 , BGA package  1600  is similar to BGA package  1500  shown in  FIG. 15 , except that substrate  502  in BGA package  1500  includes two conductive layers (first and second metal layers  106  and  504 ) instead of a single conductive layer. 
     Other features of BGA package  1600  are similar to the corresponding features in aforementioned designs. 
     Design 17—Partially Depopulated Package with a One-Piece Stiffener/Die Paddle/Heat Slug 
       FIG. 17  shows a BGA package  1700 , according to an embodiment of the present invention. As shown in  FIG. 17 , BGA package  1700  incorporates a one-piece stiffener/die paddle/heat slug  1702  such that die  114  sits directly on top of stiffener/die paddle/heat slug  1702 . BGA package  1700  provides excellent thermal performance, as heat directly dissipates from die  114  through die attach epoxy  116  and stiffener/die paddle/heat slug  1702  to an attached motherboard (not shown). 
     Other features of BGA package  1700  are similar to the corresponding features in aforementioned designs. 
     Design 18—Partially Depopulated Package with a One-Piece Stiffener/Die Paddle/Heat Slug 
       FIG. 18  shows a BGA package  1800 , according to an embodiment of the present invention. As shown in  FIG. 18 , BGA package  1800  is similar to BGA package  1700  shown in  FIG. 17 , except that substrate  502  of BGA package  1800  includes two conductive layers (first and second metal layers  106  and  504 ) instead of a single conductive layer. 
     Other features of BGA package  1800  are similar to the corresponding features in aforementioned designs. 
     Note that all of the above designs may be manufactured in wafer saw format for maximized material utilization. 
     Refer to Table 2 below, which provides a brief overview of the above described embodiments/designs. 
     
       
         
               
               
               
             
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Design 
                 Description 
                 Advantages 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 1 ML substrate + thick 
                 Fully populated thermally enhanced 
               
               
                   
                 stiffener with selective 
                 package (Use Adhesive Base 
               
               
                   
                 plating 
                 Polymide) 
               
               
                   
                   
                 Ground bond on heat spreader 
               
               
                 2 
                 1 ML substrate + thick 
                 Fully populated thermally enhanced 
               
               
                   
                 stiffener with selective 
                 package 
               
               
                   
                 plating 
                 (Use Adhesiveless Base Polyimide) 
               
               
                 3, 4 
                 Two pieces stiffener with 
                 To achieve split ground function 
               
               
                   
                 selective plating 
                 (analog &amp; digital ground) with 
               
               
                   
                   
                 dielectric adhesive material 
               
               
                 5 
                 2 ML substrate + thick 
                 To improve routability, electrical 
               
               
                   
                 stiffener with selective 
                 and thermal performance 
               
               
                   
                 plating 
                   
               
               
                 6 
                 4 ML substrate + thick 
                 Excellent routability, electrical and 
               
               
                   
                 stiffener with selective 
                 thermal performance 
               
               
                   
                 plating 
                   
               
               
                 7 
                 1 ML substrate + thick 
                 To improve signal integrity for noise 
               
               
                   
                 stiffener with selective 
                 reduction by grounding the 
               
               
                   
                 plating + active ground ball 
                 discharge current through the ground 
               
               
                   
                 connect to heat spreader 
                 bond, stiffener and discharge to the 
               
               
                   
                   
                 mother board 
               
               
                 8 
                 2 ML substrate + thick 
                 To improve routability, electrical 
               
               
                   
                 stiffener with selective 
                 and thermal performance 
               
               
                   
                 plating + active ground ball 
                 To improve signal integrity for noise 
               
               
                   
                 connect to heat spreader 
                 reduction by grounding the 
               
               
                   
                   
                 discharge current through the ground 
               
               
                   
                   
                 bond, stiffener and discharge to the 
               
               
                   
                   
                 mother board 
               
               
                 9 
                 1 ML substrate + thick 
                 To improve the thermal performance 
               
               
                   
                 stiffener with selective 
                 by exposing the die paddle through 
               
               
                   
                 plating + window opening 
                 window punched opening 
               
               
                   
                   
                 To improve plating traces routability 
               
               
                   
                   
                 through debussing window punched 
               
               
                   
                   
                 opening 
               
               
                 10 
                 2 ML substrate + thick 
                 To improve routability, electrical 
               
               
                   
                 stiffener with selective 
                 and thermal performance 
               
               
                   
                 plating + window opening 
                 To improve the thermal performance 
               
               
                   
                   
                 by exposing the die paddle through 
               
               
                   
                   
                 window punched opening 
               
               
                   
                   
                 To improve plating traces routability 
               
               
                   
                   
                 through debussing window punched 
               
               
                   
                   
                 opening 
               
               
                 11 
                 1 ML substrate + thick 
                 Excellent thermal performance. 
               
               
                   
                 stiffener with selective 
                 Direct conductive heat dissipation 
               
               
                   
                 plating + window opening + 
                 from silicon thru epoxy, stiffener, 
               
               
                   
                 drop-in heat slug 
                 heat slug to mother board 
               
               
                   
                   
                 To improve plating traces routability 
               
               
                   
                   
                 through debussing window punched 
               
               
                   
                   
                 opening 
               
               
                 12 
                 2 ML substrate + thick 
                 Excellent thermal performance. 
               
               
                   
                 stiffener with selective 
                 Direct conductive heat dissipation 
               
               
                   
                 plating + window opening + 
                 from silicon thru epoxy, stiffener, 
               
               
                   
                 drop-in heat slug 
                 heat slug to mother board 
               
               
                   
                   
                 To improve plating traces routability 
               
               
                   
                   
                 through debussing window punched 
               
               
                   
                   
                 opening 
               
               
                   
                   
                 To improve routability, electrical 
               
               
                   
                   
                 and thermal peformance 
               
               
                 13 
                 1 ML substrate + thick 
                 Excellent thermal performance. 
               
               
                   
                 stiffener with selective 
                 Direct conductive heat dissipation 
               
               
                   
                 plating + window opening + 
                 from silicon thru epoxy, stiffener, 
               
               
                   
                 drop-in heat slug with 
                 heat slug to mother board 
               
               
                   
                 mechanical locking 
                 To improve plating traces routability 
               
               
                   
                 mechanism 
                 through debussing window punched 
               
               
                   
                   
                 opening 
               
               
                   
                   
                 To improve heat slug adhesion by 
               
               
                   
                   
                 increasing the contact surface area 
               
               
                 14 
                 2 ML substrate + thick 
                 Excellent thermal performance. 
               
               
                   
                 stiffener with selective 
                 Direct conductive heat dissipation 
               
               
                   
                 plating + window opening + 
                 from silicon thru epoxy, stiffener, 
               
               
                   
                 drop-in heat slug with 
                 heat slug to mother board 
               
               
                   
                 mechanical locking 
                 To improve plating traces routability 
               
               
                   
                 mechanism 
                 through debussing window punched 
               
               
                   
                   
                 opening 
               
               
                   
                   
                 To improve routability, electrical 
               
               
                   
                   
                 and thermal peformance 
               
               
                   
                   
                 To improve heat slug adhesion by 
               
               
                   
                   
                 increasing the contact surface area 
               
               
                 15 
                 1 ML substrate + thick 
                 To improve the thermal performance 
               
               
                   
                 stiffener with selective 
                 by exposing the die paddle through 
               
               
                   
                 plating + down set paddle + 
                 window punched opening 
               
               
                   
                 window opening 
                 To improve plating traces routability 
               
               
                   
                   
                 through debussing window punched 
               
               
                   
                   
                 opening 
               
               
                   
                   
                 Lower package thickness profile by 
               
               
                   
                   
                 applying down-set die paddle 
               
               
                   
                   
                 construction 
               
               
                 16 
                 2 ML substrate + thick 
                 To improve the thermal performance 
               
               
                   
                 stiffener with selective 
                 by exposing the die paddle through 
               
               
                   
                 plating + down set paddle + 
                 window punched opening 
               
               
                   
                 window opening 
                 To improve plating traces routability 
               
               
                   
                   
                 through debussing window punched 
               
               
                   
                   
                 opening 
               
               
                   
                   
                 Lower package thickness profile by 
               
               
                   
                   
                 applying down-set die paddle 
               
               
                   
                   
                 construction 
               
               
                   
                   
                 To improve routability, electrical 
               
               
                   
                   
                 and thermal performance 
               
               
                 17 
                 1 ML substrate + thick 
                 Excellent thermal performance. 
               
               
                   
                 stiffener with selective 
                 Direct conductive heat dissipation 
               
               
                   
                 plating + stiffener window 
                 from silicon thru epoxy, stiffener, 
               
               
                   
                 opening + tape opening + 
                 heat slug to mother board 
               
               
                   
                 die paddle heat slug 
                 To improve plating traces routability 
               
               
                   
                   
                 through debussing window punched 
               
               
                   
                   
                 opening 
               
               
                   
                   
                 One-piece stiffener, die paddle and 
               
               
                   
                   
                 heat slug concept 
               
               
                 18 
                 2 ML substrate + thick 
                 Excellent thermal performance. 
               
               
                   
                 stiffener with selective 
                 Direct conductive heat dissipation 
               
               
                   
                 plating + stiffener window 
                 from silicon thru epoxy, stiffener, 
               
               
                   
                 opening + tape opening + 
                 heat slug to mother board 
               
               
                   
                 die paddle heat slug 
                 To improve plating traces routability 
               
               
                   
                   
                 through debussing window punched 
               
               
                   
                   
                 opening 
               
               
                   
                   
                 One-piece stiffener, die paddle and 
               
               
                   
                   
                 heat slug concept 
               
               
                   
                   
                 To improve routability, electrical 
               
               
                   
                   
                 and thermal performance 
               
               
                   
               
             
          
         
       
     
     CONCLUSION 
     Although the invention herein has been described with reference to particular embodiments, it is to be understood that the embodiments are merely illustrative of the principles and application of the present invention. It is therefore to be understood that various modifications may be made to the above mentioned embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention. For example, Design 5 could be modified to incorporate two stiffeners to achieve split grounding. In fact any of the above mentioned designs may be combined with any other design or designs to produce a new package.