FR2811508A1 - Radio communications equipment module having components printed circuit board mounted with outer/lower interconnection conductors providing electromagnetic screening/electrical interconnections. - Google Patents

Abstract

The radio communications module is mounted on a mother board and has components mounted on a printed circuit board. The printed circuit board has conductors (121) distributed on the lower face providing at the same time electromagnetic screening and electrical interconnections plugging into motherboard.

Description

Radiocommunication module in the form of a macro

  electronic component, interposition structure and reporting method on

a matching motherboard.

  The field of the invention is that of radiocommunications.

  More specifically, the invention relates to radiocommunication equipment (radiotelephone, and more generally any apparatus or device implementing radiocommunications), and more particularly the

  radiocommunication modules intended for this equipment.

  It will be recalled that, conventionally, most radiocommunication equipment comprises a radiocommunication module presenting a card, that is to say a printed circuit, on which components are soldered, a shielding structure and a mechanical connector allowing

  the interconnection of the module with other elements, such as a motherboard.

  The components soldered to the printed circuit can in particular perform digital processing, analog processing, and / or radio frequency processing functions. The shielding structure makes it possible to electromagnetically shield the radiocommunication module, and is conventionally made up of two belts, disposed respectively on each of the faces of the integrated circuit, and of two covers which can be respectively clipped onto

each side of the module.

  A conventional architecture for GSM type radiocommunication modules consists of an electronic card, produced on an organic substrate, and enclosed in a metal enclosure ensuring the functionality of electromagnetic shielding. This card is interconnected via card-to-card or cable-to-cable connectors. The card can then be transferred to a card

  mother mechanically by screws, or by welding of metal pins.

  In the field of radiocommunications, one of the main concerns of the manufacturers is to design and produce components and modules of radiocommunications which are space-saving, of reduced cost,

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  and a great simplicity of assembly, and in particular with regard to the postponement

  on an integrated circuit or a motherboard.

  To meet this triple objective, radiocommunication specialists

have considered several solutions.

  Thus, Ericsson (registered trademark) presented a radiofrequency module, comprising an integrated circuit produced on a ceramic substrate, in which balls or welding columns were used to simultaneously ensure the passage of electrical signals, and the transfer of the module to a card. mother according to

  CMS technology (Surface Mounted Components).

  IBM (registered trademark) also proposed the design of a radiofrequency component, for which a first row of solder balls ensured the passage of the electrical signals and a second row of solder balls allowed the shielding of the component, these balls also allowing to weld the

component on a circuit.

  Other manufacturers in the electronics field have also thought of designing hybrid modules, comprising several components of assembly level "1", for which balls or welding columns simultaneously fulfilled the functionalities of electrical interconnection and

  transfer of the module to a motherboard.

  However, despite numerous research efforts to try to meet the three criteria of low cost, small size, and ease of assembly and transfer, it has not yet been possible to design a module for

  which meets these three economic and technical objectives.

  A drawback of the techniques of the prior art is in particular that the transfer of the radio communication modules to a motherboard is not done in a standard manner, according to a reflow technique similar to that used for the

  soldering of a component on a card.

  Another drawback of these techniques of the prior art is that the radio communication modules obtained according to one of these techniques are of a

great thickness.

  Yet another drawback of these techniques of the prior art is that the radio communication modules obtained according to one of these techniques are expensive. The invention particularly aims to overcome these drawbacks of the prior art. More specifically, an objective of the invention is to provide a module for

  cost-effective radiocommunication.

  Another objective of the invention is to implement a module for

  thin radiocommunication.

  Yet another objective of the invention is to provide a radiocommunication module which can be transferred to a motherboard according to a standard reflow technique, similar to that used for fixing the surface-mounted components, so as to be able to ensure a transfer in

industrial environment of volume.

  These objectives, as well as others which will appear subsequently, are achieved according to the invention, using a module for radiocommunication equipment, intended to be transferred to a motherboard and comprising components mounted on a printed circuit. and providing at least one of the following functions: RF processing, digital processing and analog processing, comprising a set of conductive elements, distributed on the underside of the printed circuit, and produced so that the set of conductive elements constitutes both : - electromagnetic shielding means of the underside of the printed circuit; - electrical interconnection means, ensuring the passage of electrical signals to and / or from the motherboard; and - means for transferring the radiocommunication module to the motherboard; so that the radiocommunication module forms an electronic macro-component. The term “component” is understood here to mean any type of component, and in particular both the components of assembly levels "1" (simple components) and the components of assembly levels "2" (more components

  complex, such as packages or integrated circuits).

  Thus, the invention is based on a completely new and inventive approach to the design of radio communication modules, which simultaneously satisfy the criteria of low cost, small footprint, and ease of transfer to a

motherboard.

  Indeed, in the field of electronics, and a fortiori of radiocommunications, the person skilled in the art has always been reluctant to use a single element to fulfill distinct functionalities. This is indeed an area in which the interactions between elements and / or components are very strong, and therefore often make the operation of a complex module unpredictable. Such a forecast is all the more difficult to achieve since the module includes a large number of components, and that, moreover, the same element

  of the module can combine several distinct functionalities.

  The combination of two functions, such as electrical interconnection and electromagnetic shielding for example, within the same element such as a solder ball, and a fortiori, the implementation of a single set of elements conductors to simultaneously perform electrical interconnection, electromagnetic shielding and transfer of the module to a motherboard, therefore results from a

complex process.

  Indeed, a person skilled in the art who would have envisaged such a triple combination of functionalities within the same element would have been naturally inclined to reject this solution for technical reasons of non-feasibility or non-control of the effects due to each features. A radio communication module in fact comprises, on the one hand, level components

  assembly "1" and "2", and on the other hand, a printed circuit which can be multi-

  face. Such a module therefore generally undergoes several so-called reflow stages, and a person skilled in the art considers that it is not possible to carry out more than two rejections (otherwise, some previously welded components could come off

  during this additional step).

  According to an advantageous characteristic of the invention, the radiocommunication module is included in a device belonging to the group comprising: - radiocommunication terminals; - devices, other than radiocommunication terminals, requiring wireless communication functionality;

- modems.

  Thus, the module produced according to the invention finds numerous applications in the field of radiocommunications, and can in particular be used in

  radiocommunication terminals such as mobile phones.

  Advantageously, the set of conductive elements comprises a first sub-

  set of conductive elements, ensuring the electromagnetic shielding of the module, and a second subset of conductive elements, ensuring electrical interconnection, the first and second subset of conductive elements together ensuring the

transfer to the motherboard.

  Unlike the techniques of the prior art, the same set of conductive elements therefore simultaneously performs the three functions of electromagnetic shielding, electrical interconnection, and transfer to the motherboard. Such a triple combination of functionalities thus makes it possible to reduce the bulk.

  and the cost of the radiocommunication module according to the invention.

  According to an advantageous technique of the invention, the conductive elements belong to the group comprising: - columns; - marbles; - solder and / or solder deposits; - inserts;

- lyres.

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  By lyres is meant here the legs of a component having a lyre shape.

  It is thus possible to envisage using solder balls, or preferably solder columns, which are less bulky. In fact, the soldering columns make it possible to ensure a sufficient height between the motherboard and the underside of the printed circuit, and thus to prevent the components fixed on the underside of the printed circuit from coming into contact with the motherboard. , while occupying a

  small surface of the printed circuit and the motherboard.

  More generally, the conductive elements distributed on the underside of the printed circuit can consist of any type of conductive contact allowing a mechanical and electrical connection to be made between the radiocommunication module, presented in the form of a macro electronic component,

and a motherboard.

  According to an advantageous embodiment of the invention, the radiocommunication module comprises an interposing structure, a first face of which supports the set of conductive elements, so as to allow a transfer of the interposing structure, by its first face , on the underside of the printed circuit, the interposing structure being transferred by its second face to the motherboard. Such an interposing structure in fact makes it possible to maintain a minimum distance between the radiocommunication module and the motherboard, and more precisely between the underside of the printed circuit and the motherboard, so that the components fixed to the face bottom of the circuit board are not in contact with the motherboard. Such a distance can be appreciably of the order

of 1, Smrm.

  Furthermore, the interposition structure is chosen so as to have a coefficient of thermal expansion which is compatible with the coefficient of thermal expansion of the radiocommunication module, so as to avoid

  possible shear problems.

  According to an advantageous characteristic, the elements supported by the first face of the interposing structure pass through and project from the second face of the interposing structure, so as to allow the postponement of the

  interposition structure, by its second face, on the motherboard.

  According to another advantageous characteristic of the invention, each of the elements supported by the first face of the interposing structure is connected to a first end of a conductive through opening, a second end of each through opening being connected to an element d '' a set of complementary conductive elements distributed on the second face of the interposition structure, the set of complementary conductive elements allowing the transfer of the interposition structure, by its second face, on the motherboard According to a mode of advantageous embodiment, the interposing structure can be removed after the radiocommunication module has been transferred to the motherboard. Thus, one can for example envisage that the interposing structure is removed after the transfer of the module on the motherboard, for example by a technique

  of chemical dissolution of the structure.

  Advantageously, the printed circuit is produced with an organic substrate.

  Organic substrates are generally generally less expensive than others

  types of substrates, including ceramic substrates.

  According to an advantageous characteristic, the printed circuit belongs to the group comprising: - single-sided and single-layer printed circuits; multi-sided and single-layer printed circuits; - single-sided and multi-layer printed circuits;

  - multi-sided and multi-layer printed circuits.

  The radiocommunication module can indeed reach a high level of complexity, and include a large number of components, both on the lower and upper face of the printed circuit, the electrical connections between the various components can be superimposed, in the printed circuit, on several layers. Alternatively, the radio module can be

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  of reduced complexity and consist of a single-sided and mono-

  layer. Thus, the invention is suitable for all types of multi-module

  components. The invention also relates to the interposition structure, allowing the transfer of a radiocommunication module to a motherboard, a first face of the interposition structure supporting a set of conductive elements allowing the transfer of the interposition structure. , by its first face, on the underside of a printed circuit included in the radiocommunication module, the structure

  interposition being transferred by its second face on the motherboard.

  The invention also relates to a method for transferring a radio communication module to a motherboard, the components of the module being soldered to a printed circuit during at least a first reflow step, the method comprising an additional reflow step , allowing the module to be carried over

  communication on the motherboard.

  According to another advantageous embodiment, the radiocommunication module comprising an interposing structure, a first face of which supports a set of conductive elements, said at least one first reflow step of the method also allows the interposition of the interposing structure , by its first face, on the underside of the printed circuit, and the additional reflow step allows the transfer of the interposition structure, by its

second side, on the motherboard.

  Other characteristics and advantages of the invention will appear more

  clearly on reading the following description of an embodiment

  preferential, given by way of simple illustrative and nonlimiting example, and of the appended drawings, among which: - FIG. 1 shows a radio communication module according to the invention seen from below; - Figure 2 illustrates a detail of the area 14 of Figure 1; - Figure 3 shows the module of Figure 1 after transfer to

a motherboard.

  The general principle of the invention is based on the use of a set of conductive elements to achieve the three shielding functionalities

  electromagnetic, electrical interconnection, and transfer to a motherboard.

  Referring to FIG. 1, an embodiment of a radiocommunication module according to the invention is presented. The radiocommunication module 10 comprises an integrated circuit 11, to which an interposing structure 12 has been fixed. The printed circuit 11 has two zones 131 and 132, corresponding for example respectively to a radiofrequency processing zone and to a digital processing zone and / or in baseband. These two zones dealing with very different types of signals, they are advantageously isolated by a row 15 of metal columns. The interposing structure 12 has a set of conductive elements 121 allowing

  in particular the transfer of the structure 12 to the underside of the printed circuit 11.

  An area 14 is illustrated in detail on scale 15 by FIG. 2.

  In the example described, the conductive elements are columns. A metal column 21 passes right through an interposing body 24, which can for example be made of plastic material with a thickness substantially equal to 0.5mm. The metal column 21 can be fixed to the underside of the printed circuit 25 by a high temperature solder 23. The module 26 can be attached to a motherboard by a standard solder 22 of the column 21. A column 21 can be of substantially length equal to 1.5mm and of diameter substantially equal to 0.4mm. The spacing between two successive columns 21

can be equal to 1.27mm.

  The columns can be replaced by various elements such as

  solder balls, inserts, lyres, solder deposits ...

  According to another embodiment of the invention, the interposing structure can be attached to the printed circuit on the one hand, and to a motherboard on the other hand, using two conductive elements, for example pads brazing cream, deposited on each of the faces of the interposing body 24, these two elements being connected by a metallized hole, for example made of copper. The two studs

2811508

  of solder cream then have a thickness such that the distance between the face

  bottom of the printed circuit and the motherboard is substantially equal to 1.5mm.

  The interposition structure can be final or temporary. In the latter case, it can be removed by chemical dissolution after transfer from the motherboard. It is also possible that there is no interposition structure. FIG. 3 shows the radiocommunication module of FIG. 1 after transfer to a motherboard 31. An interposing structure 34 is fixed to the radiocommunication module 32 on the one hand, and to the motherboard 31 on the other hand. The welds 33 between the motherboard 31 and the metal columns 35 of the structure

  34 may be of the CMS (Surface Mounted Components) type.

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Claims (13)

  1. Module for radiocommunication equipment, intended to be transferred to a motherboard and comprising components mounted on a printed circuit and ensuring at least one of the following functions: RF processing, digital processing and analog processing, characterized in that it comprises a set of conductive elements, distributed on the underside of said printed circuit, and produced in such a way that said set of conductive elements constitutes both: - electromagnetic shielding means of the underside of said printed circuit; - electrical interconnection means, ensuring the passage of electrical signals to and / or from said motherboard; and - means for transferring said radio communication module to said motherboard;   so that said radio module forms a macro- electronic component.   2. Radiocommunication module according to claim 1, characterized in that it is included in a device belonging to the group comprising: - radiocommunication terminals; - devices, other than radiocommunication terminals, requiring wireless communication functionality; - modems.   3. Radiocommunication module according to any one of   Claims 1 and 2, characterized in that said set of conductive elements   comprises a first subset of conductive elements, ensuring said electromagnetic shielding, and a second subset of conductive elements, ensuring said electrical interconnection, and in that said first and second subsets of conductive elements   together ensure said transfer on the motherboard.   4. Radiocommunication module according to any one of   Claims 1 to 3, characterized in that said conductive elements   belong to the group comprising: - columns; - marbles; - solder and / or solder deposits; - inserts; - lyres.   5. Radiocommunication module according to any one of   Claims 1 to 4, characterized in that it comprises a structure   interposition, a first face of which supports said set of conductive elements, so as to allow a transfer of said interposition structure, by its first face, to the underside of said printed circuit, and in that said interposition structure is carried over by its second side on the motherboard.   6. Radiocommunication module according to claim 5, characterized in that said elements supported by the first face of the interposing structure are through and project on the second face of the interposing structure, so as to allow said transfer of the structure   by its second face, on the motherboard.   7. Radiocommunication module according to claim 5, characterized in that each of said elements supported by the first face of the interposing structure is connected to a first end of a conductive through opening, a second end of each through opening being connected an element of a set of complementary conductive elements distributed on the second face of the interposing structure, said set of complementary conductive elements allowing 13 2811508   said transfer of the interposition structure, by its second face, on the motherboard 8. Radiocommunication module according to any one of   claims 5 to 7, characterized in that said interposing structure   can be removed after said radio module has been postponed on the motherboard.   9. Radiocommunication module according to any one of   Claims 1 to 8, characterized in that said printed circuit is produced with an organic substrate.   10. Radiocommunication module according to any one of   claims 1 to 9, characterized in that said printed circuit belongs to the   group comprising: - single-sided and single-layer printed circuits; multi-sided and single-layer printed circuits; - single-sided and multi-layer printed circuits;   - multi-sided and multi-layer printed circuits.   11. Interposition structure, allowing the transfer of a radiocommunication module to a motherboard, characterized in that a first face of said interposition structure supports a set of conductive elements allowing a transfer of said structure of interposition, by its first face, on the underside of a printed circuit included in said radiocommunication module, and in that said interposition structure is transferred by its second face on the motherboard.   12. Method of transferring a module to a motherboard   radiocommunication according to any one of claims 1 to 10,   said components being soldered to said printed circuit during at least one first reflow step, 14 2811508   said method being characterized in that it comprises an additional reflow step, allowing the transfer of said radiocommunication module to said motherboard.   13. The method of claim 12, said radiocommunication module comprising an interposing structure, a first face of which supports said set of conductive elements, characterized in that said at least one first reflow step also allows the transfer of said structure d interposition, by its first face, on the underside of said printed circuit, and in that said additional reflow step allows the postponement of   said interposition structure, by its second face, on the motherboard.