Abstract:
Utilization of the “dead space” previously occupied by a metal stiffener in an integrated circuit package as a location for power conditioning and converting mechanisms such as de-coupling capacitors and planar transformers.

Description:
FIELD OF THE INVENTION 
     The field of the invention is integrated circuit packaging. 
     BACKGROUND OF THE INVENTION 
     As the amount of power required by ICs increases, there is increasing difficulty in passing sufficient power through interconnects to the ICs. To make the issue worse, as the IC power has risen, the voltages have dropped from 5 V to 3.3 V, then to 1.2 V, and now approach 1V. This increase in power and decrease in voltage has caused the current required to increase rapidly. At the same time the number of I/O&#39;s and the switching rates are increasing while the I/O pitch on the chip is decreasing. All of this causes high dI/dt power noise which make clean power distribution difficult. Although the use of decoupling capacitors can help reduce such noise, building capacitors into a substrate filled with high density visa tends to be difficult and costly. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to utilizing the “dead space” previously occupied by a metal stiffener in an integrated circuit package as a location for power conditioning and converting mechanisms such as de-coupling capacitors and planar transformers. 
     Various objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, along with the accompanying drawings in which like numerals represent like components. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top perspective view of a first combination embodying the invention. 
     FIG. 2 is an exploded cross-sectional view of the combination of FIG.  1 . 
     FIG. 3 is a detailed view of second combination embodying the invention. 
     FIG. 4 is side cutaway view of a first FLIP-CHIP MLBGA combination embodying the invention. 
     FIG. 5 is side cutaway view of a WIRE BONDED TBGA combination embodying the invention. 
     FIG. 6 is side cutaway view of a second FLIP-CHIP MLBGA combination embodying the invention. 
     FIG. 7 is an exploded perspective view of a sixth combination embodying the invention. 
     FIG. 8 is a top view of the printed circuit card and IC of FIG.  7 . 
     FIG. 9 is a top view of the PCF of FIG.  7 . 
     FIG. 10 is an exploded perspective view of a seventh combination embodying the invention. 
     FIG. 11 is a top view of the printed circuit board and IC of FIG.  10 . 
     FIG. 12 is a top view of the PCF of FIG.  10 . 
    
    
     DETAILED DESCRIPTION 
     An IC package typically comprises an interconnect to which an IC is connected, and a copper stiffening frame which either surrounds the IC or covers one side of the package. In place of the typical solid frame, a power conditioning frame (PCF) comprising power conditioning and possibly converting mechanisms can be used. Power provided to the interconnect would pass through the PCF, back into the interconnect, and then into the IC. 
     The standard frames take up a relatively large amount of space so power conditioning frames sized similarly can contain sizable decoupling capacitors. Moreover, by moving de-coupling capacitors and similar devices off of the interconnect, the interconnect can be more fully tested without damaging such devices. After separate testing, the power conditioning frame and the interconnect can be coupled together. It is also contemplated to bring power into the interconnect at a higher voltage and use a PCF to step it down to power the I/O and logic portions of the IC. The ability to step down the voltage in the PCF greatly simplifies power distribution as it reduces the number of visa needed to transfer power through the interconnect. Moreover, moving any power conditioning off of the interconnect and into the PCF will likely shorten signal paths with a resulting decrease in inductance. 
     The use of a PCF to take advantage of dead space can also be accomplished where an IC is mounted directly to a printed circuit board (PCB) or card (PCC). In such embodiments, the interconnect comprises the PCB or PCC with the PCF having the same relationship to the IC and PCB/PCC as it does to an IC and interconnect combination. For the sake of simplicity, the term interconnect as used herein also includes PCBS and PCC&#39;s. 
     Referring first to FIGS. 1 and 2, an IC package combination comprises an interconnect  10 , an IC/die  20 , and a PCF  30 . When viewed from the top, as shown in FIGS. 8 and 11, the outer perimeters of interconnect  10  and IC  20  form substantially rectangular footprints with the footprint of IC  20  being smaller than and falling within the footprint of interconnect  10 . PCF  30  is sized and dimensioned to fit within the dead space which falls outside the footprint of IC  20 , but inside the footprint of interconnect  10 . When viewed from the side it can be seen that both IC  20  and PCF  30  are preferably coupled to the same surface of interconnect  10 . 
     Referring to FIG. 5, the IC package combination may be in a wire bonded TBGA form or, referring to FIGS. 4 and 6, in a flip-chip MLBGA form, or any other form which has sufficient dead space within which the PCF can be included. As shown in FIGS. 4-6 a power/ground decoupling layer  40  may also be part of the interconnect (FIGS. 5 and 6) or as part of the PCF (FIG.  4 ). Referring to FIGS. 7 and 10, the combination may also include a thermal transfer layer/copper plate  51  and/or a heat sink  52 . 
     Interconnect  10  can comprise any combination of materials but will typically comprise a first conductive pattern  11  and a second conductive pattern  12 . The patterns  11  and  12  are typically electrically connected so as to allow the pattern  21  of IC  20  to be electrically connected to a printed wiring board (PCB) through interconnect  10 . Referring to FIG. 3, interconnect  10  may comprise a power input pad  13 , a via  14 , pads  15   a  and  15   b , vias  16  and  18 , component  17 , and pad  19 . Pad  13 , via  14 , and pad  15 A provide a path for power to pass through interconnect  10  to pad  32  of PCF  30 . The power path then continues through PCF  30 , back into interconnect  10  via pad  15 B and through interconnect  10  by way of pad  15 B, via  16 , component  17 , via  18 , and pad  19  into power input pad  22  of IC  20 . It can thus be seen that, in at least some embodiments, interconnect  10  will comprise a broken conductive path between a power input pad of the interconnect and a power input pad of the IC which is closed/bridged by PCF  30 . Although other embodiments of interconnect  10  may comprise structures which vary widely from that shown in FIG. 3, it is contemplated that all preferred embodiments will comprise at least one power path which must be closed/bridged by PCF  30  before power provided to interconnect  10  can flow into IC  20 . As previously discussed, interconnect  10  may, among others, be a PCB (FIG. 10) or PCC (FIG. 7) and/or may be used as the PCB of a multi-chip module (MCM). 
     As used herein, a power pad is a pad used to transfer power into or out of the IC, interconnect, or PCF. A conditioning pad is simply a pad which is part of the interconnect but is used to electrically connect the PCF to the interconnect. An interconnect power input pad is simply a pad used to transfer power into the interconnect so that it subsequently can be transferred through the PCF and then into the IC. A PCF is essentially a power or signal conditioning circuit sized and dimensioned to fit within the open space which results from the differences in sizes between the IC and the interconnect, and which can be assembled and tested separately from both the interconnect and the IC. 
     IC  20  can comprise any combination of materials but typically will comprise a conductive pattern  21  sized and dimensioned so as to make the use of interconnect  10  advantageous. 
     PCF  30  is preferred to comprise a conductive pattern  31  and at least one bridging component  34 . Conductive pattern  31  is preferred to comprise at least one power input pad  32  and at least one power output pad  36  with visa  33  and  35  and component  34  providing a conductive path between pad  32  and pad  36 . 
     Component  34  may be any type of component and thus might be, among others, a simply conductor, a resistor, a capacitor, an inductor, or a planar transformers. Instead of a single device, component  34  may comprise a network of homogeneous or diverse devices. 
     PCF  30  is preferred to be sized and dimensioned to fit within the dead space which results from the difference in sizes between an IC and its interconnect (see FIGS.  7 - 12 ). Although some embodiments may be frame shaped and comprise an inner hollow in which the IC fits so as to take advantage of all of the available dead space, other embodiments may utilize only a portion of the space and thus comprise a “thin” frame or to simply have a rectangular or other non-frame shape. In less preferred embodiments the PCF may be taller than the IC and/or may extend beyond the footprint of the interconnect. 
     It is contemplated that PCF  30  might also incorporate a thermal electric cooler or fan, may have other uses than power conditioning, and/or may be a passive, semi-active, or active device. 
     In some embodiments it may be advantageous to utilize ICs having power provided on the outside pads nearest there perimeters and logic inputs on the inside pads. Thus reversing the typical arrangement which utilizes inside pads as power inputs and outside pads as logic/signal inputs. 
     A combination utilizing a PCF as described may be assembled by, providing a known good IC; providing a known good interconnect; providing a known good PCF; coupling the IC to the interconnect; and coupling the PCF to the interconnect. 
     PCF  30  may condition one or more signals of provided by interconnect  10  in any number of ways including, but not necessarily limited to stepping voltages up or down, and filtering to provide spike protection and/or eliminate noise. 
     Thus, specific embodiments and applications of combinations utilizing power conditioning frames have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. As an example, some embodiments may couple the PCF directly to the IC so that power or other signals provided to the interconnect pass through the PCF and then to the IC without reentering the interconnect. As an alternative example, the devices and methods disclosed herein might be applied to MOMS and PCBS as well as IC packages. Yet another alternative may condition non-power signals such that the PCF acts as a signal conditioning frame rather than a power conditioning frame. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.