Abstract:
An electronic device includes a support plate having a mounting face and an electrical connection network. An integrated circuit chip is mounted on the mounting face and linked to the electrical connection network. An en encapsulation block embeds the integrated circuit chip. An additional element made of an electrically conductive material is at least partly embedded within the encapsulation block. The additional conductive element has a main portion extending parallel to the support plate and has a secondary portion that is linked electrically to the integrated circuit chip. An opening is formed in the encapsulation block, and the secondary portion extends into that opening to make the electrical link. The additional conductive element may be an antenna.

Description:
PRIORITY CLAIM 
     This application claims priority from French Application for Patent No. 1557999 filed Aug. 28, 2015, the disclosure of which is incorporated by reference. 
     TECHNICAL FIELD 
     The present invention relates to the field of electronic devices. 
     BACKGROUND 
     Known electronic devices, generally of parallelepipedal form, comprise a support plate, including an electrical connection network, an integrated circuit chip mounted on one of the faces of the support plate and an encapsulation block in which the chip is embedded. The chip is linked to the network of the support plate by electrical connection elements such as balls, interposed between the support plate and the chip, or by electrical connection wires embedded in the encapsulation block. 
     Such electronic devices are mounted on printed circuit plates, generally via electrical connection elements such as balls, linking the electrical connection network of the support plates and the electrical connection network of the printed circuit plates. 
     When the chips generate radiofrequency signals that have to be transmitted or process received radiofrequency signals, the transmission or reception antennas are produced on the printed circuit plates. The electrical signals follow very long resistive paths which are formed by lines of the electrical connection network of the printed circuit plates, the electrical connection elements between the printed circuit plates and the support plates, lines of the electrical connection network of the support plates and the electrical connection elements between the support plates. Such paths further depend on the quality of the interconnections obtained from the fabrication. 
     The above provisions constitute a handicap notably when the necessary dimension of the antennas, for the transmission of radiofrequency signals at frequencies of the order of a gigahertz or above, even very much greater than a gigahertz, become reduced. 
     SUMMARY 
     According to one embodiment, an electronic device is proposed that comprises a support plate having a mounting face and including an electrical connection network, at least one integrated circuit chip, mounted on said mounting face of the support plate and linked to said electrical connection network, an encapsulation block in which the chip is embedded, this encapsulation block extending over the chip and around the latter on said mounting face of the support plate, and at least one additional element made of an electrically conductive material, at least partly embedded in said encapsulation block, this additional conductive element having at least one main portion extending parallel to said support plate and having at least one secondary portion linked electrically to said chip. 
     Said secondary portion of the additional conductive element can be linked to at least one electrical contact formed on said mounting face of said support plate at a distance from the periphery of the chip. 
     Said secondary portion of the additional conductive element can be linked to at least one electrical contact formed on a front face of said chip. 
     Said secondary portion of said additional conductive element can be folded back towards the support plate relative to its main portion. 
     A soldering material can be interposed between said secondary portion of said additional conductive element and said electrical contact of the support plate. 
     Said encapsulation block can have a cavity at least partially revealing said main portion of said additional conductive element. 
     Said main portion of said additional conductive element can extend over and at a distance from the chip. 
     Said additional conductive element can constitute a radiofrequency antenna. 
     Said encapsulation block can comprise two superposed parts between which said additional conductive element extends. 
     A method for fabricating an electronic device is also proposed, in which there is available a primary electronic device comprising a support plate, an integrated circuit chip mounted on a mounting face of the support plate and a primary encapsulation block extending over the chip and around the chip on said mounting face of the support plate, the encapsulation block having a front face parallel to the support plate; and an additional element made of an electrically conductive material, formed so as to have at least one main portion and at least one secondary portion. 
     The method comprises: producing a hole through said primary encapsulation block of the primary electronic device, from its front face, to at least partially reveal an electrical contact of said mounting face of said support plate or of the chip; installing said additional conductive element in a position such that its main portion extends over said front face of the primary encapsulation block and its secondary portion is linked to said electrical contact in said hole; and producing an additional encapsulation block on said primary encapsulation block of said primary electronic device, the primary encapsulation block and the additional block constituting a final encapsulation block in which said additional conductive element is at least partially embedded. 
     The method can comprise: having available an additional conductive element having a secondary portion folded back relative to its main portion and installing the additional conductive element in a position such that this secondary portion is engaged in said hole of the encapsulation block of the primary electronic device. 
     The method can comprise: linking the secondary portion of said additional conductive element to said electrical contact by soldering material. 
     The method can comprise: producing a groove in the front face of the primary encapsulation block of the primary electronic device and installing at least said main part of said additional conductive element in this groove. 
     The method can comprise: at least partly bonding said additional conductive element on the front face of the primary encapsulation block of the primary electronic device. 
     The method can comprise: producing a void in the additional encapsulation block, so as to partially reveal said main part of said additional conductive element. 
     The method can comprise: before installing said additional conductive element, producing a void in said primary encapsulation block of the primary electronic device and installing said additional conductive element in a position such that said main portion of this additional conductive element totally covers and closes this void. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Electronic devices and their fabrication methods will now be described as exemplary embodiments, illustrated by the drawing in which: 
         FIG. 1  represents a cross section of an electronic device; 
         FIG. 2  represents a plan view of the electronic device of  FIG. 1 ; 
         FIG. 3  represents a step of fabrication, in cross section, of the electronic device of  FIG. 1 ; 
         FIG. 4  represents another step of fabrication, in cross section, of the electronic device of  FIG. 1 ; 
         FIG. 5  represents another step of fabrication, in cross section, of the electronic device of  FIG. 1 ; 
         FIG. 6  represents another step of fabrication, in cross section, of the electronic device of  FIG. 1 ; 
         FIG. 7  represents a cross section of another electronic device; 
         FIG. 8  represents a cross section of another electronic device; 
         FIG. 9  represents a cross section of another electronic device; and 
         FIG. 10  represents a plan view of the electronic device of  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION 
     As illustrated in  FIGS. 1 and 2 , according to an exemplary embodiment, a final electronic device  1  comprises a support plate  2 , including an integrated electrical connection network  3 , an integrated circuit chip  4  mounted on a front mounting face  5  of the support plate  2  and a final encapsulation block  6  in which the chip  4  is embedded and which extends over the chip  4  and around the latter, on the mounting face  5  of the support plate  2 , such that the electronic device  1  takes the form of a parallelepiped. 
     According to a variant embodiment represented, the integrated circuit chip  4  is mounted on the mounting face  5  of the support plate  2  via electrical connection elements  7 , such as balls, which selectively link the chip  4  and the electrical connection network  3 . According to another variant embodiment, the chip  4  could be bonded onto the mounting face  5  of the support plate  2  and be linked to the electrical connection network  3  by electrical connection wires embedded in the encapsulation block  6 . 
     The electronic device  1  further comprises an additional integrated element  7 ′ made of an electrically conductive material, preferably rigid, embedded in the encapsulation block  6 . 
     The additional conductive element  7 ′ comprises a main portion  8  which extends parallel to the mounting face  5  of the support plate  2  and a secondary portion  9  which links the main portion  8  to an electrical contact  10  of the electrical connection network  3  via a soldering material  11 , this electrical contact  10  being formed on the mounting face  5  of the support plate  2  and being situated at a distance from and outside the periphery of the chip  4  and at a distance from and inside the periphery of the encapsulation block  6 . 
     According to a variant embodiment represented, the main portion  8  of the additional conductive element  7 ′ extends over and at a distance from the chip  4  and the secondary portion  9  is folded back towards the support plate  2  relative to the main portion  8 . 
     The additional conductive element  7 ′, prefabricated, can for example be formed by stamping an elongate metal sheet of which the main portion  8  is flat above and at a distance from the support plate  2  and the chip  4 , a secondary portion  9  being able to be reduced to a folded-back tab. The additional conductive element  7 ′ can be obtained by cutting a metal plate and forming at the same time or after the cutting. 
     The electronic device  1  can be provided with external electrical connection elements  12 , such as balls, arranged on electrical contacts  13  of the electrical connection network  3  formed on a face  14  of the support plate  2 , opposite the mounting face  5 , these electrical contacts  13  being linked selectively to the electrical connection network  3  of the support plate  2 . 
     The electronic device  1  can be produced as follows. 
     As illustrated in  FIG. 3 , there is a primary electronic device  15  available, prefabricated, which comprises the support plate  2 , the chip  4  mounted as described previously and a primary encapsulation block  16  in which the chip  4  is embedded and which extends, around the chip  4 , over the mounting face  5  of the support plate  2 . The primary encapsulation block  16  has a front face  17  which is parallel to the support plate  2  and which extends over and at a distance from the chip  4 . 
     As illustrated in  FIG. 4 , a hole  18  is produced locally through the primary encapsulation block  16 , from its front face  17 , at a point situated between the periphery of the chip  4  and the periphery of the primary encapsulation block  16 , so as to reveal the electrical contact  10 . Then, a drop of a soldering material  11  is deposited at the bottom of the hole  18  on the electrical contact  10 . 
     Next, as illustrated in  FIG. 5 , the additional conductive element  7 ′, prefabricated by forming and cutting, is installed on the primary encapsulation block  16 , in a position such that its primary portion  8  extends over the front face  17  and its secondary portion  9  is engaged in the hole  18 , the end of the secondary portion coming into contact on the soldering material  11 . 
     Then, optionally, at least the part of the main portion  8  furthest away from the secondary portion  9 , for example, is bonded onto the front face  17  using a spot of glue  19 . According to a variant embodiment, illustrated optionally in  FIG. 2 , a positioning groove  16   a  emerging in the hole  18  could be produced in the front face  17  of the primary encapsulation block  16 , the main portion  8  of the additional conductive element  7  being able to be inserted into this groove  16   a  and thus positioned and held in place. 
     Next, the electrical device  15  is passed into an oven to produce the soldering of the secondary portion  9  of the additional conductive element  7 ′ on the electrical contact  10  via the soldering material  11 , the additional conductive element  7 ′ being held by virtue of the spot of glue  19 . 
     Next, as illustrated in  FIG. 6 , an additional encapsulation block  20  is produced on the primary encapsulation block  16  so as to cover the additional conductive element  7 ′, such that the primary encapsulation block  16  and the additional encapsulation block  20  constitute the final encapsulation block  6  and that the final electronic device  1  is obtained as described previously with reference to  FIGS. 1 and 2 . 
     As illustrated in  FIG. 7 , according to another exemplary embodiment, the final electronic device  1  can be considered as a new primary electronic device  21 , on which steps equivalent to the steps described above with reference to  FIGS. 4 to 6  are carried out, for example as follows. 
     A hole  22  is produced in or through the encapsulation block  6  from its front face  6   a , at a point different from that of the previous hole  18 , so as to reveal another electrical contact  23  of the electrical connection network  3 , this other electrical contact  23  being formed on the mounting face  5  of the support plate  2 . 
     Then, a drop of a soldering material  24  is deposited on this electrical contact  23  at the bottom of the hole  22 . 
     Next, another additional conductive element  25 , equivalent to the additional conductive element  7 , is installed, with a main portion placed on the front face  6   a  of the encapsulation block  6  and a secondary part engaged in the hole  22  to be placed on the drop  24 . Then, the soldering is done. 
     Finally, another additional encapsulation block  26  is produced on the encapsulation block  6 , covering the other additional conductive element  25 , so as to form another final encapsulation block  27  consisting of the encapsulation block  6  and of the additional encapsulation block  26 . 
     A final electronic device  28  is then obtained that is equipped with the two additional conductive elements  7 ′ and  25 , embedded in this final encapsulation block  27 . 
     As illustrated in  FIG. 8 , according to another exemplary embodiment, a final electronic device  28  is differentiated from the electronic device  1  described previously by the fact that it comprises an additional conductive element  29  of which the secondary portion  30  is, this time, directly linked to a specific electrical contact  31  provided on the front face  32  of the chip  4 . The specific electrical contact  31  can result from the formation of an electrical link passing through the substrate from the integrated circuit chip  4 , known by the name TSV (Through Silicon Via). 
     In this exemplary embodiment, the fabrication step, equivalent to that described with reference to  FIG. 4 , consists in producing a hole  33  through the primary encapsulation block  16 , at a point situated over the chip  4 , so as to reveal the electrical contact  31 . The subsequent steps of installation of an additional conductive element  7  and of production of an additional encapsulation block  20  are equivalent to those described with reference to  FIGS. 5 and 6 . 
     As illustrated in  FIGS. 9 and 10 , according to another exemplary embodiment, a final electronic device  34  is differentiated from the electronic device  1  described previously by the fact that it comprises a formation of a cavity  35  in a final encapsulation block  6 , open outwards and partially revealing the main portion  8  of the additional conductive element  7 ′. 
     The cavity  35  comprises an opening  36  formed through the additional encapsulation block  20 , to the main portion  8  of the additional conductive element  7 ′. This opening  36  is produced after the step of production of the additional encapsulation block  20 . 
     The cavity  35  further comprises a void  37  formed under the main portion  8  of the additional conductive element  7 ′, for example between the front face  38  of the chip  4  opposite the support plate  2  and this main portion  8 . 
     The void  37  is produced in the step described with reference to  FIG. 4 , before the placement of the additional conductive element  7 ′. The main portion  8  of the additional conductive element  7 ′ completely covers the void  37  so that, during the step of production of the additional encapsulation block  20 , the material forming this block  26  does not penetrate into this void  37 . 
     Moreover, the front face  38  of the chip  4  can be covered by a metallic layer  39 . The main portion  8  of the additional conductive element  7 ′ can serve to form a radiofrequency antenna and the metallic layer  39  can in this case serve as ground plane for said antenna. 
     According to a variant embodiment, the main portion  8  of the additional conductive element  7 ′ could be perforated. 
     A cavity equivalent to the cavity  35  could be produced in the electronic devices described with reference to  FIGS. 7 and 8 . 
     In the case where the main portion  8  of the additional conductive element  7 ′ forms a radiofrequency antenna, the cavity  35  and the void  37  formed under the main portion  8  of the additional conductive element  7 ′ offer the advantage of making it possible to access the main portion  8  to deform it and/or perforate it, in order to adjust the electromagnetic characteristics of the antenna. This adjustment operation can be performed after the fabrication of the final device  34  is finished and the latter has been mounted and tested in the desired application. 
     The electronic devices which have just been described can be obtained by a collective fabrication on a common support wafer, as is known in the microelectronics field. The encapsulation blocks and the additional encapsulation blocks can be obtained by spreading a liquid material, for example an epoxy resin, then by hardening this material. 
     Of course, the additional conductive elements of the electronic devices can take any desired topographic forms. 
     The additional conductive elements of the electronic devices which have just been described, included in the final encapsulation block, can advantageously constitute electromagnetic antennas for the transmission/reception of radiofrequency signals at very high frequencies (up to a gigahertz or above a gigahertz, even several hundred gigahertz), linked to the chip  4  by short electrical connection paths, via the electrical connection network of the support plate  2  ( FIG. 1 ) or directly ( FIG. 8 ).