Multi-level electronic module assembly

An assembly of electronic modules comprises electronic modules supported by a support structure. Each electronic module is in the form of electronic components stacked on at least two levels which are separated by an intermediate layer. Each electronic module comprises at least one hole formed in the intermediate layer. The support structure comprises at least one rod element that is introduced into respective holes of successive modules.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention concerns an assembly of electronic modules. This 
assembly comprises a plurality of electronic modules supported by a 
support structure. 
2. Description of the Prior Art 
Each electronic module is in the form of electronic components stacked on 
at least two levels which are separated by an intermediate dielectric 
layer. By way of non-limiting example, American patent U.S. Pat. No. 
5,309,122 and U.S. patent application Ser. No. 08/825,956 each propose a 
particular type of electronic module. 
American patent U.S. Pat. No. 4,987,425 proposes an assembly of electronic 
modules forming an antenna with radiating elements. The assembly uses a 
support structure made from a carbon fibre material that is metalized on 
its surface to assure a shielding and heat evacuation function. This 
support structure defines a plurality of individual cells disposed in a 
matrix in the manner of "honeycomb". The electronic modules are disposed 
inside these cells. On its upper surface the support structure supports an 
antenna body to which radiating elements are fixed. Each radiating element 
radiates in response to receiving an output signal produced by an 
electronic module. The lower surface of the support structure defines a 
base supporting conductive connecting elements adapted to apply input 
signals to the electronic modules. 
A first disadvantage of the assembly described in this American patent U.S. 
Pat. No. 4,987,425 is the use of a relatively bulky support structure. 
Moreover, reducing the weight of the support structure implies the use of 
a carbon fiber material that is covered with a metallic layer. This 
metalization step makes the manufacture of the support structure more 
difficult. Moreover, the evacuation of the heat produced by the electronic 
modules is not optimal. 
A first object of the invention is to provide an assembly of electronic 
modules in which the support structure is less bulky and simpler to 
manufacture than in the prior art. Another object of the invention is to 
offer an assembly offering better heat evacuation than in the prior art. 
SUMMARY OF THE INVENTION 
To this end, an assembly of electronic modules in accordance with the 
invention comprises a plurality of electronic modules supported by a 
support structure wherein each of said electronic modules is in the form 
of electronic components stacked on at least two levels which are 
separated by an intermediate layer, said electronic modules each comprises 
at least one hole formed in said intermediate layer, and said support 
structure comprises at least one rod element that is introduced into 
respective holes of successive modules. 
In one embodiment the at least one rod element is rectilinear and is 
introduced into respective holes of aligned successive modules. 
In another embodiment each module element includes two orthogonal holes, 
said modules are disposed in a matrix, and at least a first rod element is 
introduced into respective successive holes of electronic modules disposed 
in a line and at least one second rod element is introduced into 
respective successive holes of electronic modules disposed in a column. 
The rod elements can support module separator plate elements. These plate 
elements assure electromagnetic shielding between components. 
The rod elements are advantageously made from a material having a high 
thermal conductivity. 
Other features and advantages of the present invention will emerge more 
clearly from a reading of the following description given with reference 
to the corresponding accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 1 and 2, a multi-level electronic module 10 is in the 
form of electronic components 100, 101, 102 and 103 stacked on at least 
two levels. Two electronic components, for example, 102 and 103, at two 
respective levels are separated by an intermediate layer 110 typically of 
a dielectric material. If the assembly is intended to form part of an 
active antenna a radiating element 104 can be fixed to one face of the 
electronic module 10. Components at different levels are connected by 
connecting means 105. A connection is made by a coplanar line such as that 
described in U.S. patent application Ser. No. 08/825,956, for example, a 
metalized via, etc. 
In accordance with the invention, each module of the assembly includes at 
least one hole H formed in a dielectric intermediate layer 110. This hole 
H does not cross any connection 105 (see FIG. 2). As will become clear in 
what follows, in the case of a module at one end of the assembly the hole 
H can be a blind hole; elsewhere this hole typically passed completely 
through the module 1. 
Referring to FIG. 3, in accordance with the invention, the support 
structure comprises at least one rod element, for example the rod element 
40, which is introduced into the respective holes H of successive modules. 
For the rod element 40 these modules are designated 12, 15 and 18. It is 
feasible for the assembly to comprises only electronic modules disposed in 
a line. In this case a single rod element is provided. The rod element is 
rectilinear and is introduced into the respective holes of the successive 
modules, which are aligned. The assembly typically comprises a printed 
circuit 50 receiving one face of each of the modules. 
In practice, for active antenna applications, the modules are disposed in a 
matrix, as shown in FIG. 3. In this case, each module 10 through 21 
comprises two holes H1 and H2 on respective orthogonal axes and offset 
relative to each other. The two holes are disposed so that they do not 
cross any connection 105 and do not cross each other. First rod elements 
40, 41 and 42 are each introduced into respective successive holes of 
electronic modules disposed in a line (L) 12-15-18, 11-14-17 and 10-13-16 
and second rod elements 43 are each introduced into respective successive 
holes of electronic modules disposed in a column (C) 16-17-18. 
Separator and shielding plate elements 30, 31, 32 and 33 can advantageously 
be provided to isolate each given module electromagnetically from the 
adjacent module(s). To this end, the separator and shielding plate 
elements 30, 31, 32 and 33 are each provided with slot(s) and/or hole(s) 
for fixing them to the rod elements 40, 41, 42 and 43. In the embodiment 
shown in FIG. 3, each column separator plate 30, 31 and 32 has N=3 holes 
320 respectively adapted to receive the N first rod elements 40, 41 and 
42. Each first rod element, for example element 40, therefore passes in 
succession through a hole H2 of a module 18, a hole 320 of a separator 
plate 31, a hole H2 of a module 15, and so on. Furthermore, each line 
separator plate 33 is provided with slots 330, 331 into each of which an 
edge of a second rod element 43 and/or a column separator plate 30, 31 and 
32 is introduced. 
For maximal evacuation of heat generated by the component(s) of each 
module, each rod elements 40, 41, 42 and 43 acts as a heatsink. To this 
end, the rod elements are advantageously made from a material having a 
high thermal conductivity. Furthermore, as an alternative to this, all the 
rod elements 40, 41, 42 and 43 are hollow and are connected to a heat 
evacuation system (not shown). This heat evacuation system circulates a 
heat exchange fluid in the rod elements 40, 41, 42 and 43. 
As shown in FIG. 4, for two levels of electronic components 100 and 101, 
the components on these two levels can be mounted on a dissipative 
material 120 having high thermal conductivity. The printed circuit 50 is 
typically made from this material, for example. This material 120 
therefore delimits two faces of the hole H receiving a rod element. The 
rod element is mounted in this hole H in contact with the material 120 so 
as to optimise heat evacuation. 
The invention described hereinabove applies to radiating antennas, for 
example.