High frequency chip packages with connecting elements

Abstract

A radio frequency chip package is formed by assembling a connecting element such as a circuit board or flexible circuit tape having chips thereon with a bottom plane element such as a lead frame incorporating a large thermally-conductive plate and leads projecting upwardly from the plane of the plate. The assembly step places the rear surfaces of the chips on the bottom side of the connecting element into proximity with the thermal conductor and joins the conductive traces on the connecting element with the leads. The resulting assembly is encapsulated, leaving terminals at the bottom ends of the leads exposed. The encapsulated assembly may be surface-mounted to a circuit board. The leads provide robust electrical connections between the connecting element and the circuit board.

1 . A method of making a microelectronic package comprising: 
 (a) assembling (i) a subassembly incorporating a connecting element with top and bottom surfaces and also incorporating one or more lower chips mounted to said bottom surface with (ii) a bottom plane element including a thermal conductor, said assembling step being performed so that said one or more lower chips overlie said thermal conductor and said connecting element is disposed above said thermal conductor and said one or more lower chips; and    (b) electrically connecting said connecting element to active terminals substantially coplanar with said thermal conductor.    
     
     
         2 . A method as claimed in  claim 1  wherein said bottom plane element includes active leads projecting upwardly from said active terminals, whereby said connecting element is juxtaposed with said active leads in said assembling step, said electrically connecting step including electrically connecting conductive elements of said connecting element to said active leads.  
     
     
         3 . A method as claimed in  claim 2  wherein said step of providing said bottom plane element includes providing a unitary lead frame including said active leads, said active terminals and said thermal conductor, the method further comprising the step of disconnecting the active terminals and active leads from said thermal conductor after said assembling step.  
     
     
         4 . A method as claimed in  claim 3  further comprising the step of encapsulating said active leads, connecting element and chips so as to leave said active terminals and thermal conductor exposed, said disconnecting step including removing temporary elements of said lead frame after said encapsulating step.  
     
     
         5 . A method of making a microelectronic package comprising: 
 (a) assembling    (i) a subassembly incorporating a connecting element with top and bottom surfaces and one or more lower chips mounted to said bottom surface, said one or more lower chips having surfaces remote from said connecting element defining a lower datum and    (ii) a separate bottom plane element including active terminals lying at or below said lower datum; and    (b) electrically connecting said connecting element to said terminals.    
     
     
         6 . A method as claimed in  claim 5  wherein said bottom plane element has terminal leads projecting upwardly from said terminals, said terminal leads having upper ends, and said connecting element includes a dielectric layer having traces thereon extending to lands exposed at said bottom surface, said assembling step being performed so as to engage said lands with said upper ends of said terminal leads.  
     
     
         7 . A method as claimed in  claim 5  wherein said bottom plane element includes an inductor, the method further comprising connecting said inductor to said connecting element.  
     
     
         8 . A method as claimed in  claim 5  wherein said bottom plane element includes a lead frame.  
     
     
         9 . A packaged chip comprising: 
 (a) a bottom package element and a top package element, each said package element having an upwardly facing top surface and a downwardly facing bottom surface, said top package element including a plurality of conductive elements, said top chip carrier overlying said bottom chip carrier so as to define an interior space between said chip carriers, said conductive elements of said top package element including top terminals exposed at said top surface of said top package element;    (b) one or more chips disposed in said interior space and connected to at least some of said terminals of at least one of said package elements; and    (c) one or more chips disposed above said top package element and connected to at least some of said terminals of said top package element wherein said conductive elements of said top package element substantially block radiative propagation of radio frequency energy between said one or more chips disposed in said interior space and said one or more chips disposed above said top package element.    
     
     
         10 . A packaged chip as claimed in  claim 9  wherein said conductive elements of said bottom package element includes bottom terminals exposed at said bottom surface of said bottom package element.  
     
     
         11 . A packaged chip as claimed in  claim 9  further comprising interconnect pillars extending between said top and bottom package elements and interconnecting at least some of the conductive elements on said package elements with one another.  
     
     
         12 . A packaged chip as claimed in  claim 9  further comprising leads extending into or through said interior space, at least some of said conductive features of said top and bottom package elements being interconnected with one another through said leads.  
     
     
         13 . A packaged chip as claimed in  claim 12  wherein said leads include bottom leads extending between said second chip and said bottom package element and top leads extending between said second chip and said top package element.  
     
     
         14 . A packaged chip as claimed in  claim 9  further comprising a cap panel overlying said top package element and defining a top space between said cap panel and said top package element, said cap panel including conductive elements defining at least a part of an antenna.  
     
     
         15 . A packaged chip as claimed in  claim 14  wherein said conductive elements of said cap panel define a shield disposed between said antenna and said top space.  
     
     
         16 . A packaged chip as claimed in  claim 9  wherein said top and bottom package elements and said cap panel include integral portions of a unitary sheet, said unitary sheet having at least two folds therein.  
     
     
         17 . An electronic assembly comprising: 
 (a) a first chip including a radio frequency power amplifier (RFPA);    (b) at least one other chip disposed in vertically stacked relation to said first chip;    (c) a package holding said chips, said package including bottom terminals adapted for mounting to a circuit panel, interconnection between said chips and shielding adapted to substantially block radiative propagation of radio frequency energy between said first chip and said at least one other chip.    
     
     
         18 . An electronic assembly as claimed in  claim 17  further comprising shielding between said first chip and a space external to said assembly.  
     
     
         19 . An electronic assembly as claimed in  claim 18  wherein said package further includes at least a portion of an antenna.  
     
     
         20 . An electronic assembly as claimed in  claim 17  wherein said bottom terminals are adapted for surface mounting to a circuit panel.  
     
     
         21 . An electronic assembly as claimed in  claim 17  wherein said shielding is adapted to shield said at least one other chip from RF energy radiated from said first chip.  
     
     
         22 . A portable electronic communication device including an electronic assembly as claimed in  claim 17 .  
     
     
         23 . A handset including a portable electronic communication device as claimed in  claim 22 .  
     
     
         24 . A cellular mobile communication device including a handset as claimed in  claim 23 .  
     
     
         25 . An electronic assembly comprising: 
 (a) a first chip including a radio frequency power amplifier (RFPA) adapted to produce at least 10 milliwatts RF power;    (b) a second chip including a surface acoustic wave chip;    (c) a package holding said first and second chips, said package including bottom terminals adapted for mounting to a circuit panel and shielding between said first chip and said second chip.    
     
     
         26 . An electronic assembly as claimed in  claim 25  further comprising shielding between said first chip and a space external to said assembly.  
     
     
         27 . An electronic assembly as claimed in  claim 25  wherein said package further includes at least a portion of an antenna.  
     
     
         28 . An electronic assembly as claimed in  claim 25  wherein said package occupies a volume of less than about 0.5 cm 3 .  
     
     
         29 . An electronic assembly as claimed in  claim 25  wherein said shielding is adapted to shield said at least one second chip from RF energy radiated from said first chip.  
     
     
         30 . An electronic assembly as claimed in  claim 25  wherein said bottom terminals are adapted for surface mounting to a circuit panel.  
     
     
         31 . A portable electronic communication device including an electronic assembly as claimed in  claim 25 .  
     
     
         32 . A handset including a portable electronic communication device as claimed in  claim 31 .  
     
     
         33 . A cellular mobile communication device including a handset as claimed in  claim 32 .  
     
     
         34 . A packaged chip comprising: 
 (a) at least one lower chip; and    (b) a top package element extending above said at least one lower chip and extending in horizontal directions beyond said at least one lower chip, a chip of said at least one lower chip being mounted to said top package element; and    (c) a plurality of leads extending downwardly from said top package element,    wherein said top package element and said leads substantially block radiative propagation of radio frequency energy between said at least one lower chip and a space above said top package element.    
     
     
         35 . A packaged chip as claimed in  claim 34  wherein said leads form an enclosure extending around edges of said at least one lower chip such that said leads substantially block radiative propagation of radio frequency energy between said at least one lower chip and a space external to said enclosure.  
     
     
         36 . A packaged chip as claimed in  claim 34  wherein said leads are selected from the group consisting of pre-formed solder features, pillars, wire bonds, and leads formed integrally to a said chip carrier.  
     
     
         37 . A packaged chip as claimed in  claim 34  wherein at least one of said one or more lower chips includes at least one functional element selected from the group consisting of radio frequency (RF) transmitter, RF power amplifier, RF energy switch, and filter.  
     
     
         38 . A packaged chip as claimed in  claim 37  wherein said at least one lower chip includes a filter of the surface acoustic wave type.  
     
     
         39 . A packaged chip as claimed in  claim 38  further comprising one or more upper chips disposed above said package element, said one or more upper chips including at least one functional element selected from the group consisting of RF receiver, low noise amplifier, RF mixer, IF mixer, sampler, oscillator, and signal processor.