DESCRIPTION
Title of the invention: Moisture-resistant electronic component and process for
producing such a component
[0001] The present invention relates to an electronic component, in particular a
radiofrequency component, that is resistant to moisture. It also relates to a process
for producing an electronic component, in particular a radiofrequency component.
[0002] The field of the invention is in particular that of radiofrequency microelectronics
packaging, especially for producing radiofrequency packages that include shielding
that is integrated and resistant to moisture. These packages are for example used in
complex radiofrequency equipment such as airborne radar. More generally, the field
of application is that of narrowband or wideband radiofrequency equipment, the
packages being usable in all high-frequency applications, even those with high signal
integrity specifications.
[0003] The currently proposed moisture-resistant radiofrequency packaging
technologies rely on the use of inorganic materials or on encapsulation of the
components using injected organic resins. The inorganic solutions employ in
particular sealed metal packages with glass beads for the inputs/outputs or ceramics.
[0004] The solutions using inorganic materials have several drawbacks. In particular,
what is obtained are:
- heavy and expensive packages, due to the metal or ceramic materials used;
- bulky solutions, using in particular packages with internal cavities, very often
with peripheral interconnections;
- solutions for which the reliability of mounting, in the equipment in question, is
generally problematic, because of differences in expansion coefficient with the
printed circuit boards to which they are joined.
[0005] In the case of injected organic packaging, the end result is objects which are
generally intrinsically unshielded electrically and which therefore cannot be used
as they are in complex equipment where crosstalk is a critical parameter. The
package usually encountered is what is known the QFN (quad flat no-lead)
package which has generally peripheral inputs and outputs.
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[0006] There is a need for compact packages that comply with the following
constraints:
- protecting the encapsulated functions from moisture, in particular to take all of
the MMIC (microwave monolithic integrated circuit) technologies into account;
- obtaining good reliability of mounting;
- retaining the possibility of changing the packages on the board;
- being suitable for dissipating heat;
- having 3D capability, that is to say, according to the architecture, even with
ultra-compact packages, stacking radiofrequency functions according to the
integration density of the chips used.
[0007] Radiofrequency applications require the use of
III-V semiconductors with high charge mobility. These components operate in
analogue mode and are therefore very sensitive to the quality of the interconnections
that they use and to the interference that they may encounter. In addition, since they
operate at significant voltages and currents, the electronic components (transistors,
capacitors, resistors, etc.) may be subject to corrosion effects when they are in
operation, for example electrochemical corrosion through difference in Nernst
potential.
[0008] To avoid any problem of reliability, manufacturers first developed sealed
packages that use inorganic materials (metals or ceramics as mentioned
previously) which are heavy and bulky. In order to decrease the weight, the
volume and the cost of manufacturing of the radiofrequency packaging, plastic
packages have begun to be developed with a loss of electromagnetic
performance that is substantial but acceptable for narrowband applications such
as mobile telephony.
[0009] The field of electronics packaging has been the subject of numerous
developments. The BGA (ball grid array)-type package with surface
interconnections was developed in response to the QFP (quad flat pack)
technology with peripheral interconnections in order to increase the
interconnection density. This BGA-type package has experienced substantial
growth for silicon semiconductor-based digital applications.
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[0010] In the field of radiofrequency organic packaging, many solutions have also
been developed. Solutions that may be cited include CSP (chip scale package)
technology for narrowband applications with an operational frequency below 2.17
GHz. Plastic packages capable of managing heat dissipation of about 60 W to
100 W have also been developed for applications ranging up to 2.17 GHz. There
are QFN-type plastic packages for high-frequency applications, up to 35 GHz, in
narrowband. QFN- or TSOP (thin small outline package)-type plastic packages
operate up to 12 GHz. A package with a cavity using a thermoplastic material
referred to as LCP (liquid crystal polymer) was developed at the end of the 2000s
for high-frequency applications. During the same period, the concept of packaging
for radiofrequency applications using LTCC (low temperature cofired ceramic)
technology and LCP organic materials emerged. The QFP (quad flat pack)-type
package, with a cavity, has allowed encapsulation of a wideband function with
satisfactory performance.
[0011] Additionally, patent applications FR 2849346 and FR 2877537 describe BGA
organic packaging technology with a cavity.
[0012] As has been mentioned previously, the only moisture-resistant radiofrequency
packaging technologies that are compatible with all of the MMICs rely on the use
of inorganic materials (metal packages with glass beads for the inputs and
outputs or ceramic packages), or on the encapsulation of the components using
injected organic resins. The solutions based on inorganic materials lead to the
use of heavy and expensive packages, and are bulky, particularly because of the
internal cavities and the peripheral interconnections. The solutions based on
organic materials have the major drawback of not being electrically shielded, and
therefore cannot be used in complex equipment where crosstalk is a critical
parameter without additional partitioning.
[0013] Document EP 3089211 describes an electronic component comprising an
electronic circuit and a stack of layers made of organic materials forming a cavity on
a carrier, the electronic circuit being housed in the cavity filled with a material
exhibiting low permeability to water vapour. This component complies with the
constraints mentioned above. However, this component requires a structure with a
dual mechanical reference related to the bonding of the back face of the
encapsulated circuit. This structure is necessary for the electrical ground connection
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used by the component for operation and for contact with a heat sink in order to
efficiently remove the heat produced by the circuit during its operation. This structure
represents a mechanical difficulty which is overcome by means of a step of
deforming the interconnect layer, making it possible to solve the problem of a dual
mechanical reference during lamination. The deformation step is difficult to
implement since it may cause damage to the connections of the encapsulated circuit.
[0014] The invention aims to overcome all or some the problems mentioned above by
providing both an electronic component that is highly resistant to moisture capable of
encapsulating AsGa (gallium arsenide) and GaN (gallium nitride) semiconductors in a
high-performance manner, with integrated shielding, and a process for producing
such a component that is easy to implement and without a risk of damaging the
connections of the electronic circuits encapsulated in the component.
[0015] To this end, the subject of the invention is an electronic component comprising
a first set comprising an interconnect layer and an electronic circuit having a front
face and a back face, which is connected to the interconnect layer by the front face,
the first set comprising:
a. a metal plate having a front face and a back face joined to the back face
of the electronic circuit;
b. a coupling agent between the front face of the metal plate and the back
face of the electronic circuit, configured to thermally and electrically
connect the metal plate to the electronic circuit;
and the electronic component comprising:
c. one or more layers made of organic materials stacked around the first set
using a printed circuit-type technique and encapsulating the electronic
circuit;
d. a thermally conductive metal surface arranged at least partially in contact
with the back face of the metal plate.
[0016] Advantageously, the electronic component comprises an array of metal
elements arranged at a distance from the electronic circuit so as to form a
Faraday cage containing the electronic circuit.
[0017] Advantageously, the array of metal elements is arranged on the perimeter of
the electronic component.
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[0018] Advantageously, the array of metal elements is arranged on the periphery of
the electronic component.
[0019] Advantageously, at least one of the one or more layers made of organic
materials is a layer made of thermoplastic material.
[0020] The invention also relates to a process for producing an electronic component
comprising a first set comprising an interconnect layer and an electronic circuit
having a front face and a back face, which is connected to the interconnect layer
by the front face, the process comprising the following steps:
a. joining a metal plate having a front face and a back face to the back face
of the electronic circuit;
b. thermally and electrically coupling the metal plate to the electronic circuit
using a coupling agent between the front face of the metal plate and the
back face of the electronic circuit;
c. stacking one or more layers made of organic materials around the first
set and the metal plate using a printed circuit-type technique and
encapsulating the electronic circuit forming an assembly;
d. laminating the assembly;
e. producing a thermally conductive metal surface arranged at least partially
in contact with the back face of the metal plate.
[0021] Advantageously, the production process according to the invention comprises
a step of producing shielding for the electronic circuit using an array of metal
elements arranged at a distance from the electronic circuit so as to form a
Faraday cage containing the electronic circuit.
[0022] Advantageously, the step of producing shielding for the electronic circuit
comprises a step of arranging the array of metal elements on the perimeter of the
electronic component.
[0023] Advantageously, the step of producing shielding for the electronic circuit
comprises a step of arranging the array of metal elements on the periphery of the
electronic component.
[0024] Advantageously, the step of producing the thermally conductive metal surface
arranged at least partially in contact with the back face of the metal plate
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comprises a step of machining the electronic component towards the back face of
the metal plate and a metallization step.
[0025] The invention will be better understood and further advantages will become
apparent upon reading the detailed description of one embodiment provided by way
of example, which description is illustrated by the attached drawing, in which:
[0026] [Fig.1] Figure 1 schematically shows a sectional view of an electronic
component known from the prior art;
[0027] [Fig.2] Figure 2 schematically shows a sectional view of an electronic
component according to the invention;
[0028] [Fig.3] Figure 3 schematically shows a sectional view of one embodiment of an
electronic component according to the invention;
[0029] [Fig.4] Figure 4 schematically shows a sectional view of another embodiment
of an electronic component according to the invention;
[0030] [Fig.5] Figure 5 schematically shows the steps of a process according to the
invention;
[0031] [Fig.6] Figure 6 schematically shows the joining and coupling steps of the
process according to the invention;
[0032] [Fig.7] Figure 7 schematically shows the stacking step of the process
according to the invention;
[0033] [Fig.8] Figure 8 schematically shows the lamination step of the process
according to the invention;
[0034] [Fig.9] Figure 9 schematically shows the steps of producing a thermally
conductive metal surface and of producing shielding for the electronic circuit of the
process according to the invention;
[0035] [Fig.10] Figure 10 illustrates a view from above of the electronic component
according to one exemplary embodiment of the invention.
[0036] For the sake of clarity, these figures are not all to the same scale. Moreover,
the same elements will bear the same references in various figures.
[0037] Figure 1 schematically shows a sectional view of an electronic component 5
known from the prior art. The electronic component 5 comprises a carrier 9 to which
7
is attached a first set 11 comprising an interconnect layer 12 and an electronic circuit
13 having a front face 14 and a back face 15, which is connected to the interconnect
layer 12 by the front face 14. It additionally comprises one or more layers made of
organic materials 20, 21, 22 and 23 stacked on the carrier 9. The electronic circuit 13
is enclosed in the set of these layers after manufacture, interconnected to the outside
by the structures 6. Similarly, the structures 33 arranged suitably around electronic
circuit 13 constitute a Faraday cage for protection from all outside interference.
[0038] This electronic component 5 of the prior art has a drawback in a dual
mechanical reference (7, 8) related to the bonding of the back face of the circuit. This
structure is necessary since, to operate, the electronic circuit needs to be connected
to ground via its back face 15, and for contact with a heat sink (represented by
reference 9, which may also act as a carrier) in order to efficiently remove the heat
produced by the electronic circuit during its operation. In the process for producing
such a component, the heat sink 9 and the layers 21, 22 are stacked so as to form a
cavity for the circuit 13, and then the first set 11 is positioned. Depending on the
height of the layers 21, 22, 23 around the cavity and depending on the height of the
circuit 13 and of its connection points, it is not possible to guarantee that the back
face 15 presses against the adhesive. Specifically, there are mechanical tolerances
for each element. Depending on these tolerances, the circuit 13 may not be in
contact with the adhesive at the bottom of the cavity. To ensure the bonding of the
circuit 13 at the bottom of the cavity, a step of deforming the interconnect layer 12 is
necessary, by pressing the first set 11 towards the heat sink 9. In this deformation
step, the connections of the electronic circuit 13 may be damaged. The electronic
circuit 13 itself may be damaged. Additionally, by applying pressure to the stack,
adhesive may leak over the sides of the electronic circuit 13 and lead to a short
circuit. The thickness between the back face 15 of the circuit 13 and the adhesive
before stacking is not completely controlled. The mechanical tolerances make such a
production process troublesome and difficult to control.
[0039] Figure 2 schematically shows a sectional view of an electronic component 10
according to the invention. The electronic component 10 comprises a first set 11
comprising an interconnect layer 12 and an electronic circuit 13 having a front face
14 and a back face 15, which is connected to the interconnect layer 12 by the front
face 14. According to the invention, the first set 11 comprises a metal plate 16 having
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a front face 17 and a back face 18, joined to the back face 15 of the electronic circuit
13 by a coupling agent 19 between the front face 17 of the metal plate 16 and the
back face 15 of the electronic circuit 13, which is configured to thermally and
electrically connect the metal plate 16 to the electronic circuit 13. The electronic
component 10 comprises one or more layers made of organic materials 20, 21, 22,
23, 24, 25 stacked around the first set 11 using a printed circuit-type technique and
encapsulating the electronic circuit 13. The layer 25 is a lower closing layer which
includes a sheet of copper which has been bonded on top beforehand by the material
supplier or the package manufacturer. Lastly, the electronic component 10 comprises
a thermally conductive metal surface 26 arranged at least partially in contact with the
back face 18 of the metal plate 16. Metallized holes 33 pass through the periphery of
the component in order to electrically connect the conductive plane 26 forming the
heat sink with the upper conductive plane 37 capable of supporting external
connection balls.
[0040] The metal plate 16 protects the back face 15 of the electronic circuit 13 during
the process of producing the component 10, it participates in the ground connection,
and it also participates in the thermal dissipation of the heat produced by the
electronic circuit 13 during its operation. In Figure 2, the area of the metal plate 16 is
substantially equal to that of the back face of the electronic circuit 13. However, its
area could be smaller than or equal to that of the back face of the circuit 13 in order
to facilitate its placement, or else larger in order to allow interconnections to be made
in the region where the electronic circuit 13 is not present. This latter variant also
allows the area of contact with the metal surface 26 to be increased, and hence
promotes heat dissipation.
[0041] The electronic circuit 13 may be an MMIC (monolithic microwave integrated
circuit)-type radiofrequency circuit. One of the layers, for example the layer 20, 21, 22,
23, 24, 25, may be made of LCP thermoplastic material, i.e. of a liquid crystal
polymer. This material exhibits very low permeability to water vapour. The use of an
LCP-type thermoplastic material of intrinsically very low hydrophilicity makes it
possible, when it is deformed during the production process, to fill the cavities that
may already be present between the various layers and thus obtain stacks that are
uniform and resistant to water penetration. Additionally, at its melting point, the LCP
becomes quasi-liquid and no longer exerts any mechanical stress. This property
9
makes it possible to preserve the integrity of fragile radiofrequency structures such
as the air bridges found in many MMIC-type circuits. Additionally, the use of
thermoplastic materials in the production of such a component makes it possible to
fill in all of the defects, i.e. cavities, interstices, differences in evenness, in the stack
during its manufacture. In association with rigid thermosetting materials, the use of
thermoplastic materials guarantees that mechanical dimensions essential to the
operation of the electronic component are maintained. Moreover, the use of materials
specifically developed for high-frequency uses allows the design of wideband
radiofrequency packages.. In other words, the electronic semiconductor component
10 according to the invention is "enclosed" in a stack of layers of various plastic
materials: some of these layers are made using materials that are dimensionally
"stable" in the temperature range used during the manufacturing process, and some
of these layers "melt" during the rise in temperature of the manufacturing process:
during this phase in which they are "molten", these layers fill in all of the interstices
which remain with the component and the stack. When the temperature returns to
normal, the layers become rigid again: what is obtained then is a stack very close to
that at the start, but with its holes, gaps and interstices present filled in.
[0042] The coupling agent 19 may be an adhesive providing thermal and electrical
coupling between the circuit 13 and the metal plate 16. It may also be a metal alloy
solder.
[0043] Advantageously, the electronic component 10 comprises an array 31 of metal
elements 32, 33 arranged at a distance from the electronic circuit 13 so as to form a
Faraday cage 34 containing the electronic circuit 13. The Faraday cage 34 is thus
formed between the elements 32, 33 and the lower 26 and upper 37 ground planes.
In Figure 2, the Faraday cage is (partly) represented by dashed lines.
[0044] Figure 3 schematically shows a sectional view of one embodiment of an
electronic component 10 according to the invention. In this embodiment, the array 31
of metal elements 32 is arranged on the perimeter 35 of the electronic component 10,
i.e. on the outer lateral periphery of the electronic component 10, for example by
depositing a metallized layer on the outer surface of the component, thus forming a
true shielding wall. The outer lateral periphery corresponds to the surface of the
component extending along a plane that is substantially perpendicular to the joining
plane of the component, for example and for illustration perpendicular to the
10
interconnect layer 12. It can be noted that the array 31 of metal elements 33 may
also be arranged on the periphery 36 of the electronic component, for example by
means of metallized through-holes 33. A component according to the invention may
comprise either of the variants of metal elements, or even both variants. In the case
of metallized through-holes 33, there may be two or more rows thereof, in a
staggered arrangement. Metallized holes 33 pass through the periphery of the
component in order to electrically connect the conductive plane 26 forming the heat
sink with the upper conductive plane 37 capable of supporting external connection
balls. These holes are arranged around the entire periphery 36 of the component, for
example regularly, in order to form a Faraday cage delimited by the upper conductive
plane 37 and the conductive plane 26 and by the array of metallized holes 33. Figure
10 illustrates, via a view from above of the component 10, an exemplary arrangement
of these holes 33 on the surface. What is obtained is thus packaging that is
intrinsically shielded by the formation of an internal Faraday cage coupled in a quasicoaxial interconnection mode.
[0045] The thermally conductive metal surface 26 arranged in contact with the layer
25 may be at least partially connected to the back face 18 of the metal plate 16 and
may form a surface electrical contact over the entire area of the metal plate 16 (as
shown in Figure 2), over part of the area of the metal plate 16 and/or may have an
area larger than that of the metal plate 16. The metal surface 26 may also consist of
a set of filled metallized holes, forming a plurality of surface contacts. This metal
surface may consist of copper, as explained above in the illustration of the process
for producing such a component.
[0046] Figure 4 schematically shows a sectional view of another embodiment of an
electronic component 10 according to the invention. In this embodiment, the
thickness of the metal plate 16 is greater than that of the components of the
embodiments presented in Figures 2 and 3. This results in a thicker final heat sink,
which is particularly advantageous if greater heat dissipation is required.
[0047] Figure 5 schematically shows the steps of a process according to the invention.
The process for producing an electronic component 10 comprising a first set 11
comprising an interconnect layer 12 and an electronic circuit 13 having a front face
14 and a back face 15, which is connected to the interconnect layer 12 by the front
face 14, comprises a step 101 of joining a metal plate 16 having a front face 17 and a
11
back face 18 to the back face 15 of the electronic circuit 13. After wiring the
electronic circuit 13 to the interconnect layer 12, a metal plate 16 is connected on the
back face of the electronic circuit 13. This metal plate 16 performs two functions: first,
it protects the back face of the electronic circuit 13 during the process (in particular
when machining the component at the end of the process as described below), and it
allows thermomechanical adjustment of the interface created with the organic
materials that are to be bonded on top thereof. For example, the metal plate 16 may
be made of copper, of gold-plated copper, of diamond, etc.
[0048] The process according to the invention comprises a step 102 of thermally and
electrically coupling the metal plate 16 to the electronic circuit 13 using a coupling
agent 19 between the front face 17 of the metal plate 16 and the back face 15 of the
electronic circuit 13. The thermal and electrical coupling may for example be carried
out by means of an adhesive or a solder. It then comprises a step 103 of stacking
one or more layers made of organic materials 20, 21, 22, 23, 24, 25 around the first
set 11 using a printed circuit-type technique and encapsulating the electronic circuit
13 forming an assembly 27. The production process comprises a step 104 of
laminating the assembly 27, i.e. a step of pressing and heating the assembly 27. This
step allows the films of adhesive to melt and ensures the uniformity of the stack. At
this stage in the process according to the invention, there is no heat sink positioned
beneath the electronic component 10. There is a plurality of layers made of organic
materials arranged around the first set formed by the circuit 13 and the interconnect
layer 12. In lamination step 104, the thermoplastic adhesive fills the spaces left free
in the preceding steps during the stacking step. After lamination step 104, the
electronic circuit 13 is embedded in the thermoplastic material, for example the LCP
or the FEP (abbreviation for fluorinated ethylene propylene), which ensures its later
protection from moisture.
[0049] Lastly, the process according to the invention comprises a step 105 of
producing a thermally conductive metal surface 26 arranged at least partially in
contact with the back face 18 of the metal plate 16. This step is needed to reconnect
the back face of the electronic circuit 13. Specifically, this back face 18 of the metal
plate 16 was also embedded in the LCP thermoplastic layer during the production
process.
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[0050] Figure 6 schematically shows the joining 101 and coupling 102 steps of the
process according to the invention.
[0051] Figure 7 schematically shows the stacking step 103 of the process according
to the invention. Figures 6 and 7 are schematic and aim to show the layers
separately during their assembly. By way of explanation, the interconnect layer 12 is,
once assembly has been carried out, well surrounded on all sides by the organic
layers.
[0052] Figure 8 schematically shows the lamination step 104 of the process
according to the invention.
[0053] Advantageously, the process according to the invention comprises a step 106
of producing shielding for the electronic circuit 13 using an array 31 of metal
elements 32, 33 arranged at a distance from the electronic circuit 13 so as to form a
Faraday cage 34 containing the electronic circuit 13. Step 106 of producing shielding
for the electronic circuit 13 may comprise a step 107 of arranging the array 31 of
metal elements 32 on the perimeter 35 of the electronic component 10 and/or a step
108 of arranging the array 31 of metal elements 33 on the periphery 36 of the
electronic component 10. The metallized holes, which are made between the upper
face and the lower face of the stack, allow a Faraday cage to be created, and also
allow the back ground of the semiconductor to be connected to the upper face of the
stack.
[0054] Figure 9 schematically shows the steps of producing 105 a thermally
conductive metal surface and of producing 106 shielding for the electronic circuit of
the process according to the invention.
[0055] The step 105 of producing the thermally conductive metal surface 26 arranged
at least partially in contact with the back face 18 of the metal plate 16 comprises a
step 109 of machining the electronic component 10 towards the back face 18 of the
metal plate 16 and a metallization step 110. As explained above, the back face of the
electronic circuit 13 is embedded in the thermoplastic layer. It is therefore needed to
reconnect the back face of the electronic circuit 13. The machining of the electronic
component 10 may be performed by piercing suitably arranged holes or by milling (as
shown in Figure 9), performed using a laser, or any other suitable, for example
mechanical, process. This production process implementing a step of machining the
13
component is made possible because the layers of dielectrics arranged beneath the
metal plate 16 are thin enough to avoid any problems. Additionally, the metal plate 16
provides protection for the back face of the circuit 13 during the machining step 109.
The use of a CO2 laser suits this type of process since it pyrolyses organic materials
and is reflected by metals (and therefore by the metal plate 16). Depending on the
required heat dissipation needs, it is possible either to remove almost all of the
surface beneath the electronic circuit 13 (as shown in Figure 2), or to create
connections via laser holes (as shown in Figure 3).
[0056] After machining step 109, step 110 of metallizing the machined surface takes
place. In this step, the material removed is replaced with a metal containing copper.
Advantageously, this metallization step comprises a first step of metallization in a
solution for the deposition of a few micrometres of copper, then a second step of
electrolytic surfacing in order to deposit a greater thickness of copper.
[0057] What is obtained is thus a stack allowing optimized operation for the
encapsulated electronic circuit 13, both electrically and thermally. Another advantage
resulting from the process according to the invention is that the encapsulated
electronic circuit 13 is not subjected to any mechanical stresses during the
implementation of the process. After cutting and balling, the package obtained may
be used and exhibits good electrical properties and good moisture resistance, with
significantly improved reliability in comparison with the components of the prior art.
[0058] Unlike the packaging process described in document EP 3089211, the
production process according to the invention does not address the dual mechanical
reference problem in the lamination step. The process according to the invention
takes a different approach, by dealing with the dual mechanical reference in a later
phase of the process by removing material beneath the component, i.e. on the backface side of the electronic circuit 13. In other words, the process according to the
invention does not provide a heat sink when stacking the layers around the electronic
circuit 13, or the ground connection. The heat sink and the ground connection are
produced later, after machining the component. In other words, in the prior art, the
production of such a functional stack required that the back face of the
semiconductor be bonded to the outer lower metal layer. It is this bonding which
introduces mechanical stresses onto the semiconductor, since the differences in
heights between the stack and the component meant pressing on the latter to ensure
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that it was bonded. The method of the invention makes it possible to avoid having to
bond the semiconductor to an outer lower metal layer and thus to eliminate all of the
mechanical stresses which occurred in the first process.
[0059] The process according to the invention has an advantage over using just using
a plurality of LCP layers as in the prior art. Specifically, using a plurality of LCP layers
is not enough to eliminate the need to press on the component to bond it. Being able
to bond a metal plate to the component before placing same (and its layer including
electrical connections) in the stack, as done in the invention, eliminates the need to
press thereon: this plate will protect the component in the final phases of the
manufacturing process. Specifically, after lamination, the back face of the stack is
machined (by laser) up to the plate: in the absence thereof, there would be a real risk
of destroying the component. Once an opening the size of the plate has been made,
the steps are implemented for adding metal into the cavity made. In this way, the
metal portion bonded to the component is located in the lower plane of the total stack.
The final stack obtained then has additional features as a result of these
modifications. The plate bonded to the back face of the component has been
thickened and can therefore remove the heat which will be produced by the
component during its operation. Additionally, the adhesive used is electrically
conductive (but it would also be possible to join the component using a solder alloy to
like effect), and thus allows the potential of the back face of the semiconductor to be
transferred to the back face of the stack.
[0060] The invention thus relates to the electronic component directly obtained using
the production process described above.
[0061] The production process according to the invention makes it possible to prevent
any liquid moisture from penetrating the encapsulation of the electronic circuit 13,
and therefore to eliminate any problem of electrochemical corrosion on the metal
stacks of the circuits in the presence of water electrolyte.
[0062] The "printed circuit" technology makes it possible to produce a "Faraday
cage"-type structure which allows the circuits located on the inside to be electrically
isolated and thus the problem of crosstalk from one component to another to be
eliminated.
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[0063] This results in an electronic component able to contain radiofrequency
functions which ensures sealtight properties for protecting encapsulated technologies
which are sensitive to moisture, such as MMIC technologies. The invention provides
better reliability of mounting in comparison with the current state of the art so as to be
commensurate with the level of integration. The invention also makes it possible to
minimize crosstalk problems, so as to be able to position the functions in the most
integrated manner possible. Therefore, the invention makes it possible to provide
heat dissipation commensurate with the required level of integration. Lastly, with an
electronic component according to the invention, it is possible to have the threedimensional mechanical characteristics which provide a good capacity for stacking
radiofrequency functions.
[0064] The advantage of the invention is that it improves the sealtightness of the
component, in a general manner and in complement to EP3089211. Additionally, this
type of solution represents an alternative to ASICs, MMICs, etc., has lower NRCs
(non-recurring costs) for development than other solutions known from the prior art
and constitutes a robust solution.

CLAIMS
1. Process for producing an electronic component (10) comprising a first set (11)
comprising an interconnect layer (12) and an electronic circuit (13) having a front
face (14) and a back face (15), which is connected to the interconnect layer (12) by
the front face (14), the process comprising the following steps:
a. joining (101) a metal plate (16) having a front face (17) and a
back face (18) to the back face (15) of the electronic circuit (13);
b. thermally and electrically coupling (102) the metal plate (16) to
the electronic circuit (13) using a coupling agent (19) between
the front face (17) of the metal plate (16) and the back face (15)
of the electronic circuit (13), the coupling agent being an
adhesive or a metal alloy solder;
c. stacking (103) a plurality of layers made of organic materials (20,
21, 22, 23, 24, 25) around the first set (11) and the metal plate
(16) using a printed circuit-type technique and encapsulating the
electronic circuit (13) forming an assembly (27);
d. laminating (104) the assembly (27);
e. producing (105) a thermally conductive metal surface (26)
arranged at least partially in contact with the back face (18) of
the metal plate (16).
2. Production process according to Claim 1, characterized in that it comprises a
step (106) of producing shielding for the electronic circuit (13) using an array (31) of
metal elements (32, 33) arranged at a distance from the electronic circuit (13) so as
to form a Faraday cage (34) containing the electronic circuit (13).
3. Production process according to Claim 2, characterized in that the step (106)
of producing shielding for the electronic component (13) comprises a step (107) of
arranging the array (31) of metal elements (32) on the outer lateral periphery (35) of
the electronic component (10).
4. Production process according to Claim 2, characterized in that the step (106)
of producing shielding for the electronic component (13) comprises a step (108) of
arranging the array (31) of metal elements (33) on the periphery (36) of the electronic
component (10).
5. Production process according to any one of Claims 1 to 4, characterized in
that the step (105) of producing the thermally conductive metal surface (26) arranged
at least partially in contact with the back face (18) of the metal plate (16) comprises a
17
step (109) of machining the electronic component (10) towards the back face (18) of
the metal plate (16) and a metallization step (110).
6. Electronic component (10) comprising a first set (11) comprising an
interconnect layer (12) and an electronic circuit (13) having a front face (14) and a
back face (15), which is connected to the interconnect layer (12) by the front face
(14), characterized in that the first set (11) comprises:
a. a metal plate (16) having a front face (17) and a back face (18)
joined to the back face (15) of the electronic circuit (13);
b. a coupling agent (19) between the front face (17) of the metal
plate (16) and the back face (15) of the electronic circuit (13),
configured to thermally and electrically connect the metal plate
(16) to the electronic circuit (13), the coupling agent being an
adhesive or a metal alloy solder;
and in that the electronic component (10) comprises:
c. a plurality of layers made of organic materials (20, 21, 22, 23, 24,
25) stacked around the first set (11) using a printed circuit-type
technique and encapsulating the electronic circuit (13);
d. a thermally conductive metal surface (26) arranged at least
partially in contact with the back face (18) of the metal plate (16).
7. Electronic component (10) according to Claim 6, characterized in that it
comprises an array (31) of metal elements (32, 33) arranged at a distance from the
electronic circuit (13) so as to form a Faraday cage (34) containing the electronic
circuit (13).
8. Electronic component (10) according to Claim 7, characterized in that the
array (31) of metal elements (32) is arranged on the outer lateral periphery (35) of the
electronic component (10).
9. Electronic component (10) according to Claim 7, characterized in that the
array (31) of metal elements (33) is arranged on the periphery (36) of the electronic
component.
10. Electronic component (10) according to any one of Claims 6 to 9,
characterized in that at least one of the one or more layers made of organic materials
is a layer made of thermoplastic material.