WO2002104088A1

WO2002104088A1 - Method for assembly and/or disassembly of an electronic module on an application card method for production and corresponding mechanical fixing clip

Info

Publication number: WO2002104088A1
Application number: PCT/FR2002/002128
Authority: WO
Inventors: Alexis De Bibikoff
Original assignee: Wavecom
Priority date: 2001-06-19
Filing date: 2002-06-19
Publication date: 2002-12-27
Also published as: CN1518851A; RU2003136999A; FR2826231A1; MXPA03011779A; KR20040008218A; FR2826231B1

Abstract

The invention relates to a method for assembly and/or disassembly of at least one electronic module (1) on an application card (2), said module comprising at least two component elements, that is, at least one printed circuit (12) and at least one other component element (11, 13) mechanically connected by at least one solder joint (14, 15) to said printed circuit (12), said module further comprising a set of extension elements (16) by soldering of said module (1) to an application card (2). According to the invention, said method provides a spring-effect (3) mechanical connection of said component elements (11, 12, 13) to said at least one module (1) such as to guarantee the mechanical connection after the soldering of said set of extension elements for the assembly and/or assembly of said module (1) on said application card (2).

Description

Method for mounting and / or dismantling an electronic module on an application card, manufacturing process and corresponding mechanical holding clip.

The field of the invention is that of components intended to be installed on an electronic card. More specifically, the invention relates to the mounting and dismounting of components, in particular of large size, mounted on the surface by reflow on an application card, as well as the manufacture of such components.

The invention applies in particular, but not exclusively, to the fields of radiocommunications, telecommunications, the automobile industry, electronics, and in particular on-board electronics. It can in particular be used in the field of electronic industry and component transfer, for the assembly and disassembly of macro components, hybrid components, and CMS type components (Surface Mounted Components). By macro component is meant here a module intended to be transferred to a motherboard and comprising in particular, but not exclusively, components mounted on a printed circuit, such components possibly being components of assembly level "1" (components unitary, such as a chip, a capacity, a resistance, an inductance, ...) and / or components of assembly level "2" (more complex components, such as hybrid components, boxes or circuits integrated, especially large).

To date, several techniques for extracting a component mounted by reflow on an electronic card are known.

It will be recalled that the principle of reflow of a component on a printed circuit consists in making joints between the component and the printed circuit, by melting a solder paste, consisting mainly of tin and lead in fused microbeads. Such seals generally ensure by a brazing process the mechanical and electrical connection between the component and the printed circuit on which it is installed. A first technique for extracting a component implanted on a printed circuit is based on the use of a heating plate. A resistance, crossed by an electric current, creates a thermal radiation which makes it possible to reach by contact or by thermal convection a temperature higher than the liquidus of the joints.

When the liquidus is reached, and the seals therefore no longer provide the mechanical connection of the component and the printed circuit, the component is extracted manually using tweezers, or a vacuum suction nozzle or pipette. A second known extraction technique uses a turbine, which sends air through a heating resistor. The temperature of the air leaving the nozzle can reach temperatures above 550 ° C., making it possible to reach by convection a temperature above the liquidus of the joints. In the case of a fixed reflow machine, the printed circuit is also preheated from below, via a heating cassette.

When the liquidus of the joints is reached, the component is extracted manually using tweezers or a vacuum pipette which sucks the component, or even automatically by vacuum suction nozzle.

A third known technique uses an infrared lamp, which, via an optical lens, projects an infrared conical beam onto the printed circuit. A heating cassette preheats the printed circuit from below. A temperature above the liquidus of the joints is thus locally reached, and the component is extracted manually using tweezers or a vacuum pipette, or even semi-automatically using a suction nozzle component void.

A last known technique is based on the use of a YAG laser beam (yttrium and aluminum garnet laser), which locally scans the surfaces to be rejected. A pyrometric control allows the surface temperature, linked to the scanning of the beam on the card, to be adjusted to a temperature programmed beforehand. A lower preheating station by convection is also available. The component is then automatically extracted by vacuum pipette after the liquidus temperature of the joints has been exceeded, mechanically binding it to the printed circuit on which it is installed.

A disadvantage of these techniques of the prior art results from the mode of setting of the component in reflow during the extraction. Indeed, it is more and more frequent to install on a printed circuit, or a motherboard, components, in particular of macro components type, made up of a plurality of elements mechanically linked to each other by soldering. '

However, according to the techniques of the prior art, when the component is heated to reach the reflow temperature of the joints binding it to the printed circuit on which it is installed, one also reaches, by thermal conduction, a temperature higher than the liquidus seals ensuring the mechanical cohesion of the various constituent elements of the component.

When the component is extracted using a vacuum suction pipette, only the upper component of the component is then removed from the application card. The same applies when using tweezers: some of the component elements of the component are not extracted from the printed circuit, or at the very least, the various components of the component move, at least slightly, relative to each other. others during extraction. It will be noted that a problem similar to that identified above arises during the manufacture of certain electronic modules comprising double-sided printed circuits. More specifically, in the context of the manufacture of such modules, such a problem arises during implantation by reflow of components on the second face of the printed circuit already having one or more components, and in particular heavy components, on its first face. Indeed, consider a printed circuit having one or more heavy components mechanically connected by solder to its first face. To implant one or more components on its second face, the printed circuit is turned over, so that the components already implanted on the first face are located below the printed circuit, then the printed circuit is conventionally inserted into a reflow machine (for example a reflow oven). The printed circuit is then heated to the reflow temperature of the solder paste making it possible to bond the new components to be implanted to the second face of the printed circuit. During this operation, the liquidus temperature of the joints of the first face of the printed circuit is reached by contact or by thermal conduction. The components of the first face, because of their weight, can then fall from the printed circuit, or at the very least, the soldered joints binding them to the printed circuit can stretch, thus weakening the module that one seeks to manufacture . The drawbacks of the prior art extraction techniques are presented in more detail in relation to FIGS. 1a and 1b. Note that Figure 1b corresponds to a detailed side view of Figure 1a.

We consider a macro component 1, installed on a motherboard (or application card) 2, and comprising a printed circuit 12, a shielding cover 11 and an interposing structure 13, allowing the macro component 1 to be transferred onto the printed circuit 17 of the application card 2, by means of solders 16. The shielding cover 11 is fixed to an upper face of the printed circuit 12 by brazed seals 14 made of an alloy generally of lead tin (SnPb), and the interposing structure 13 is fixed to a lower face of the printed circuit 12 by brazed seals 15. Such seals can also be made from a tin silver copper alloy (SnAgCu), or any other alloy, in particular based tin.

According to the conventional extraction techniques described above, during the remelting of the seals 16 connecting the interposing structure 13 to the printed circuit 17 of the application card 2, the seals 14 linking the shielding cover 11 to the printed circuit 12 of the macro component 1 and the seals 15 connecting the printed circuit 12 of the macro component 1 to the interposition structure 13 are, by thermal conduction, also in reflow.

Any manual extraction of component 1, using pliers or tweezers, is therefore impossible. Indeed, taking into account the fragility of the macro component 1, and the precision of assembly of its different elements (interposing structure 13, printed circuit 12, shielding cover 11), it is impossible to extract it whole from the application card 2 without deterioration. In particular, such manual extraction could for example cause a displacement of the shielding cover 11 relative to the printed circuit 12, or else a deformation of the interposing structure 13.

It will be recalled that such an interposing structure 13 makes it possible in particular to maintain a minimum distance between the electronic module 1 and the motherboard 2, and more precisely between the underside of the printed circuit 12 and the motherboard 2, so that the components fixed on the underside of the printed circuit 12 are not in contact with the motherboard 2. Such a distance can be substantially of the order of 1.5 mm, or even a lesser distance. The flatness of such an interposing structure 13 is very important: it is typically required that the interposing structure is plane to the nearest tenth of a millimeter, in particular due to the constraints linked to the thickness of the solder paste, and it It is therefore particularly important that such an interposition structure does not undergo deformation during the implantation or the extraction of the electronic module 1 on the motherboard 2.

In addition, if we considered an extraction of the macro component 1 using a pipette or a vacuum suction nozzle, which would be placed on top of the macro component 1, only the shielding cover It would be extracted. Indeed, the surface tension force of the reflow joints 14 of the cover 11 being less than the weight of the module 1, the cover 11 could be lifted by the vacuum pipette, but the rest of the component 1, and in particular the interposing structure 13 and the printed circuit 12, would remain on the card 2. Furthermore, it will be noted that the implantation of a macro component on an electronic card conventionally implements the principle of reflow described above. During such an implantation, the macro component 1 is therefore subjected to a temperature rise, which can cause the joints 14 and 15 to melt again ensuring the internal mechanical cohesion of the component. Again, such reflow can therefore lead to the displacement of the various constituent elements of the macro component 1 relative to each other, and therefore to a deterioration of the latter.

The known techniques for mounting and dismounting a component on an electronic card, as well as the known techniques for manufacturing electronic modules having double-sided printed circuits, therefore have many disadvantages.

The invention particularly aims to overcome these drawbacks of the prior art.

More specifically, an objective of the invention is to provide a technique allowing the mounting and / or dismantling of a component on an application card without deterioration or deformation of the latter.

Another objective of the invention is to provide a technique for manufacturing modules comprising double-sided printed circuits which is suitable for installing heavy components on one and / or the other face of such printed circuits.

Another objective of the invention is to provide a technique for mounting and / or dismantling electronic modules on an application card, as well as a technique for manufacturing such modules, which are simple and inexpensive to implement. . The invention also aims to implement a technique for mounting and / or dismantling a component on an electronic card which does not increase the manufacturing complexity of the latter.

Another object of the invention is to provide a mounting and / or dismounting technique for a component which is suitable for all types of electronic components, and in particular for macro components, surface mounted components and hybrid components.

These objectives, as well as others which will appear subsequently, are achieved using a method of mounting and / or dismantling an electronic module on an application card, said module comprising at least two elements. components, namely at least one printed circuit and at least one other element component mechanically connected by at least one solder to said printed circuit, said module further comprising a set of transfer elements by reflow of said module on an application card.

According to the invention, such a method implements a step of mechanical holding by spring effect of said constituent elements of said at least one module, so as to ensure mechanical cohesion during the remelting of said set of transfer elements for mounting. and / or the dismantling of said module on said application card.

Thus, the invention is based on a completely new and inventive approach to extracting and installing components on an electronic card, resulting from the identification of a new problem, linked to the structure of new components, including new macro components. Indeed, the inventors of the present patent application have identified that the conventional techniques for mounting and dismounting components by reflow on an application card, described above, were not suitable for components comprising a plurality of linked elements mechanically to each other by soldering. The invention therefore proposes, according to a new and inventive approach, to ensure the mechanical maintenance of the various constituent elements of such components, by spring effect, during their mounting and / or their dismantling of a printed circuit.

The invention also relates to a method of manufacturing at least one electronic module comprising at least two constituent elements, namely at least one printed circuit having two faces, and at least one first other constituent element mechanically connected by at least one solder to a first face of said at least one printed circuit.

According to the invention, such a method comprises a step of mechanical holding by spring effect of said at least one first other component with said at least one printed circuit, during implantation by remelting at least one second other component on a second face of said at least one printed circuit. Indeed, the problem of mechanical cohesion, identified by the inventors in the context of the implantation and / or extraction of a component from an application card, also arises during implantation by reflow on the second face of a printed circuit of one or more components, if the printed circuit already comprises one or more components mechanically connected by solder to its first face. Indeed, during this second reflow, the heavy components located on the first face, and which are suspended by the soldered joints under the printed circuit, can fall under the effect of gravitation, or at least, the joints brazed from this first face can deform, thus weakening the module during manufacture. The invention proposes a new and inventive approach to the manufacture of such modules, by envisaging mechanically maintaining by spring effect the components already implanted on the first face of the printed circuit, and in particular the heavy components, during the implantation by reflow of components on the second side. Advantageously, said electronic module is a module for radio communication equipment comprising components mounted on said at least one printed circuit and ensuring at least one of the following functions: RF processing, digital processing and analog processing, so as to form a macro electronic component. By component is meant here, and throughout the rest of the document, components of assembly level "1" (unitary components, such as a chip, a capacitance, a resistance, an inductance, etc.) as assembly level components "2" (more complex components, such as hybrid components, packages or integrated circuits, in particular of large size). According to a first alternative embodiment, said at least one other constituent element is an electronic component.

Thus, during the manufacture of an electronic module, one may wish to ensure the mechanical maintenance of an electronic component with a first face of a printed circuit, during an implantation by reflow of an element (such than an electronic component for example) on a second face of the printed circuit.

According to a second alternative embodiment, said at least one other constituent element is a shielding cover fixed by soldering on said at least one printed circuit.

The invention thus applies to components comprising a printed circuit linked by solder to an electromagnetic shielding cover which covers it.

According to a third alternative embodiment, said at least one other constituent element is an interposing structure having a lower face and an upper face, said upper face being fixed by soldering on said at least one printed circuit and said lower face being fixed by soldering on said application card using said set of transfer elements.

The invention also applies to components comprising a printed circuit, linked by solder joints to an interposing structure allowing the component to be transferred to an application card. It will be recalled that such an interposing structure makes it possible in particular to maintain a minimum distance between the electronic 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.

According to a fourth alternative embodiment, said module comprises at least the following three other constituent elements: a component, fixed by soldering on said printed circuit; a shielding cover, fixed by soldering on an upper face of said at least one printed circuit; an interposing structure having a lower face and an upper face, said upper face of said structure being fixed by soldering on a lower face of said printed circuit and said lower face of said structure being fixed by soldering on said application card to the using said set of transfer elements. Such a component can be fixed by soldering on one or the other of the faces of a double-sided printed circuit.

Preferably, said mechanical holding by spring effect is ensured by positioning a mechanical holding clip on said at least one module. It is of course also possible to envisage other alternative embodiments of the invention implementing other means for maintaining the mechanical cohesion of the component that it is desired to implant and / or extract from an application card.

The positioning of such a retaining clip on a component nevertheless constitutes a preferred embodiment of the invention.

According to an advantageous characteristic of the invention, said mechanical retaining clip is positioned on at least two modules.

We can indeed consider that the same clip simultaneously provides mechanical maintenance of two separate modules. In particular, during the manufacture of an electronic module having a double-sided printed circuit, a clip can be positioned on the heavy components implanted on a first face of the printed circuit, during implantation by reflow of one or more other components on the second side of the printed circuit.

Advantageously, said mechanical retaining clip is positioned on or near the barycenter of said at least one module.

Indeed, such positioning of the clip on the barycenter of the module ensures optimal mechanical cohesion of the latter. It is nevertheless preferable to place the clip near the barycenter, but not on the latter, so as to be able to extract the module by vacuum suction, by positioning the suction nozzle or pipette directly on the barycenter of the component to be extracted, without it being in contact with the clip. Such placement of the nozzle guarantees optimal stability of the component during its extraction and / or its implantation on an application card. It will of course be noted that when the clip is positioned simultaneously on several modules, it is preferably placed on or near the barycenter of the set of modules for which it provides mechanical support.

According to a preferred embodiment, an upper part of said clip being of substantially rectilinear shape and having a longitudinal axis, said clip is positioned on said module so that said upper part is located between said barycenter of said module and an edge of said substantially parallel module to said longitudinal axis, so that the distance between said upper part and said barycenter is less than half the distance between said edge and said barycenter.

When the barycenter of the module is not in the center of the latter, the edge of the module taken into account in the placement of the clip is the edge closest to the barycenter and parallel to the clip.

Advantageously, a disassembly method according to the invention comprises steps of: positioning of said retaining clip on said module; placing said application card in a reflow device; local heating of said module until reflow of said transfer elements, using heating elements of said reflow device; positioning of extraction means in a preemption zone of said predetermined module; extracting said module from said application card; stopping said heating elements of said module; cooling of said module; - recovery of said module on said extraction means.

Thus, when a temperature higher than the liquidus of the solder joints is reached, the component can be extracted, while guaranteeing that it will not undergo any functional or material deterioration, thanks to the prior positioning of a retaining clip, ensuring its mechanical cohesion . The reflow device used can be of the infrared, laser, or hot air type, for example. During the local heating phase of the module, the temperature is generally raised to 183 ° C, a classic eutectic in electronics of SnPb alloy seals, taking care to respect a temperature gradient of 1 to 5 ° C / s maximum. Classically, care is taken to maintain a temperature below 210 ° C. for example. For an alloy distinct from the tin lead alloy, the module is of course brought to a temperature different from 183 ° C., for example 172 ° C. in the case of a tin lead silver alloy (SnPbAg).

The extraction means used during such a disassembly process are preferably a nozzle or a vacuum suction pipette, but can also be tweezers, pliers, or any other suitable extraction means.

During the module cooling step, its temperature is lowered for example to around 120 ° C. According to an advantageous characteristic, such a disassembly method further comprises at least one of the steps belonging to the group comprising: fluxing of at least certain peripheral pins of said module; preheating of said application card, using heating elements of said reflow device. Such preheating makes it possible, for example, to raise the temperature of the application card to approximately 100 ° C., with a temperature gradient of 1 to 5 ° C. / s at most.

Preferably, said predetermined preemption zone is located near said barycenter of said module. Such a preemption zone can be located on the upper part of the module, or directly on the retaining clip.

The invention also relates to a mechanical holding clip of at least one electronic module comprising at least two constituent elements, namely at least one printed circuit and at least one other constituent element mechanically connected by at least one solder to said printed circuit, said module further comprising a set of transfer elements by reflow of said module on an application card.

Such a retaining clip comprises means making it possible to ensure the mechanical cohesion of said at least one module during the remelting of said set of transfer elements for mounting and / or dismantling said module on said application card.

The invention also relates to a mechanical holding clip of at least one electronic module comprising at least two constituent elements, namely at least one printed circuit having two faces, and at least one first other constituent element mechanically connected by at least one seal. soldered to a first face of said printed circuit.

Such a retaining clip comprises means making it possible to ensure the mechanical cohesion of said module during implantation by remelting at least one second other constituent element on a second face of said at least one printed circuit.

Thus, such a clip makes it possible to maintain the components, and in particular the heavy components, on an application card in double reflow.

It will be recalled that by double reflow means the process consisting in operating a first reflow to implant components on a first face of a printed circuit, then in effecting a second reflow to implant components on the second face of the printed circuit considered.

Advantageously, such a clip comprises an intermediate part and at least two fingers extending substantially perpendicularly to said intermediate part, each of said fingers ending in a claw returning towards the inside of said clip substantially parallel to said intermediate part.

Preferably, such a clip is preformed so that, when positioned on said module, said claws come into contact with the lower part of said module.

Thus, the claws tighten under the module, for example under the printed circuit of the module, or under the interposing structure if it exists, so that the clip grips the module and maintains its mechanical cohesion. Such a clip structure has the advantage of being simple to position on the module, and of effectively ensuring its mechanical maintenance during reflow.

Preferably, said intermediate part has at least one pressure contact line intended to come into contact with the upper part of said module, when said clip is positioned on said module.

The mechanical maintenance of the component is ensured at the level of such a contact line by pressure.

According to a first advantageous variant, said intermediate part is substantially rectilinear, so that said clip has a general U shape.

Advantageously, said intermediate part has two pressure contact lines, intended to come into contact with the upper part of said module, when said clip is positioned on said module.

The presence of two pressure contact lines increases the mechanical cohesion provided by the clip, and therefore allows the clip to be used for larger components, in particular macro components.

According to a second advantageous variant, said intermediate part has a general shape of Y, so that said clip has three fingers.

Such a multi-socket clip is particularly suitable for large components.

According to an advantageous characteristic of the invention, said intermediate part has a preemption surface, substantially coinciding with the barycenter of said module when said clip is positioned on said module.

Thus, on the one hand, the clip is positioned on the barycenter of the module to be extracted and / or to be implanted, so as to ensure optimal mechanical cohesion, and, on the other hand, the means of extraction and / or component gripping can also be positioned at the barycenter of the component. For example, provision is made in the clip for a circular surface with a diameter greater than or equal to 7 mm, so that a vacuum extraction nozzle can be positioned there to extract the component. Preferably, such a clip is formed from a material which cannot be soldered to the tin / lead alloy (SnPb).

Indeed, the clip must not be able to be fixed by soldering on the lower part of the module during reflow, so as to ensure easy removal. Preferably, such a clip has mechanical properties such that the pressure exerted by said clip on said module is greater than or equal to twice the weight of said module, when said clip is positioned on said module.

According to an advantageous technique, such a clip is preformed so as to separate from said module by pressing on one of said fingers.

Thus, the clip automatically "unclips" by pressing on one of its sides, and can therefore be easily removed from the module on which it is positioned.

Advantageously, said transfer elements being of predetermined diameter D and being spaced from each other by a pitch P, the width of said claws is greater than or equal to the sum of said diameter D and of said pitch P, and preferably to the sum of said diameter D and twice said step P.

According to an advantageous characteristic of the invention, such a clip withstands a temperature at least equal to the reflow temperature without deterioration of its mechanical properties. For example, provision is made for such a clip to withstand temperatures of the order of 300 ° C. without loss of mechanical characteristics.

According to an advantageous technique of the invention, said clip is intended to be positioned on at least two modules.

By module is meant here, and throughout the rest of the document, any type of component, namely in particular a single component, a hybrid component, or an assembly comprising a printed circuit on which one or more components are mounted.

Thus, the clip can for example maintain several heavy components on a first face of a printed circuit during the implantation of one or more other elements by reflow on a second face of this circuit. Preferably, said intermediate part has a shape complementary to that of said at least two modules on which said clip is intended to be positioned.

For example, it is conceivable that the intermediate part has a shape in stair treads, so that the clip can be positioned on several modules of different heights.

Preferably, said intermediate part has at least two pressure contact lines, each of said lines coming to bear on one of said at least two modules when said clip is positioned on said at least two modules.

Indeed, a clip intended to be positioned on several components will preferably have several support lines, so that the clip is supported on each of the components that it must maintain mechanically, for example during the manufacture of a module. electronic. Other characteristics and advantages of the invention will appear more clearly on reading the following description of a preferred embodiment, given by way of a simple illustrative and nonlimiting example, and of the appended drawings, among which: FIGS. (perspective view) and 1b (detailed side view), already described in relation to the prior art, present the structure of a macro component, which can be mounted and / or dismounted from an application card according to the method of the invention; FIGS. 2a and 2b illustrate an example of a mechanical holding clip that can be positioned on the macro component of FIG. 1 to ensure its mechanical cohesion during its implantation and / or its extraction on an electronic card; Figures 3a and 3b describe the dimensional characteristics of the mechanical holding clip of Figure 2; FIG. 4 illustrates the various stages of an example of a method for manufacturing the clip of FIG. 2; Figure 5 shows the different steps implemented when positioning the clip of Figure 2 on the macro component of Figure

1; Figures 6a, 6b and 7 illustrate other examples of mechanical holding clips that can be implemented in the context of the invention; FIG. 8 shows an example of a mechanical holding clip intended to be positioned on several components.

The general principle of the invention is based on the mechanical retention by spring effect of the various constituent elements of an electronic module during its manufacture, and / or during its assembly and / or disassembly on a printed circuit.

In a preferred embodiment of the invention, a mechanical holding clip is positioned around a module prior to its implantation or its extraction from an electronic card, or during its manufacture if such a module has a double sided printed circuit.

We present, in relation to FIGS. 2a and 2b, the mechanical principle of a retaining clip 3 which can be used, in the context of the invention, to ensure the cohesion of a macro component during its implantation and / or of its extraction by reflow on an application card, or to ensure the maintenance of components, in particular heavy components, on an application card in double reflow.

FIG. 2a shows the clip 3 in the rest position, and FIG. 2b illustrates the clip 3 when it is in the working position, that is to say when it is mounted on an electronic module or a macro component. Such a clip 3 is formed in a material which cannot be soldered to the SnPb alloy: for example, the clip 3 is produced in a metallic strip of stainless steel type, 0.2 mm thick. It will of course be noted that such a clip can be manufactured from other materials, of different thickness, depending in particular on the type of component for which it is intended. Such a clip 3 comprises an intermediate part 31, two fingers 32 and 33 each ending in a claw 34, 35, substantially perpendicular to the fingers 32, 33.

The intermediate part 31 further comprises two support lines 311, 312, corresponding to the points of contact of the intermediate part 31 with the module, when the clip 3 is positioned on the latter.

A force F, illustrated by the vertical arrows in FIG. 2a, is applied at different points of the clip 3 in the rest position. Thus, a descending vertical force F is applied to the upper ends of the fingers 32, 33, and an ascending vertical force F on the support lines 311, 312.

The application of such forces F causes the claws 34, 35 to return towards the inside of the clip 3, according to the horizontal arrows shown in FIG. 2b.

In this way, in relation to FIG. 3a, the force exerted by the electronic module 1 on the clip 3 at the level of the contact lines 311, 312 causes the claws 34, 35 to tighten towards the inside of the macro component 1. The claws 34,

35 being supported on the lower part of the macro component 1, the various elements of the latter are therefore held mechanically by the clip 3.

Note that the clip 3 must be flexible enough not to damage the component 1 during its installation. Furthermore, the clip 3 must exert on the component 1 a general pressure greater than or equal to twice the weight of the component 1, so as to ensure its mechanical cohesion when the latter is extracted from a card on which it is installed.

When the clip 3 ensures the mechanical maintenance of several components, for example heavy components implanted on an application card in double reflow, the clip 3 must exert on the components that it maintains a general pressure greater than or equal to twice the weight of all of these components.

The clip 3 must therefore be designed so that the pressure which it exerts on the component 1 achieves a compromise between the two criteria above. This compromise naturally depends on the characteristics of the component (s) 1 to which the clip 3 is intended.

We now present, in relation to Figures 3a and 3b, the dimensional characteristics of the clip 3, in a particular embodiment of the invention.

In FIG. 3 a, the length L denotes the overall length of the clip 3 in the working position, C denotes the distance between the two pressure contact lines 311 and 312, LM denotes the length or the width of the module 1, and E indicates the distance between the module's electrical connection pins. Preferably, E will be limited to the length (LM-2), expressed in millimeters.

Let E _{p be} the thickness of the material making up the clip 3. For example, we have E _p <0.2 mm, and the minimum length of the clip L _mini must verify the following equation:

L _mini = (2 x LM) - E + 4 x E _p

To ensure optimal mechanical cohesion, a value of C of approximately between 30% and 50% of the value of LM is preferably chosen.

FIG. 3b represents a bottom view of the module 1 on which a clip 3 has been positioned. The module 1 illustrated in FIG. 3b comprises an interposing structure 13, presenting a set of transfer elements 36, of diameter D and distant one step P.

In the embodiment illustrated in FIG. 3b, the width La of the claws 34, 35 of the clip 3 checks the equation:

La = 2 x P + D.

In fact, in the embodiment of FIG. 3b, the width of the claws 34, 35 of the clip 3 must be at least twice the pitch P of the electrical connections 36 of the component 1, plus the diameter D of one links 36.

When designing the clip 3, it must also be ensured that the total length of the clip 3, and in particular the length of the claws 34, 35, is adapted to the environment of the component 1. In fact, if several components are located near the module 1 on the application card, the excessively large dimensions of the clip 3 could be inconvenient when it is placed.

We now present, in relation to FIG. 4, an example of a method for manufacturing a mechanical holding clip according to the invention. During a first step referenced 41, a metal strip of stainless steel type, 0.2 mm thick, is cut to a predetermined length depending on the module to be implanted and / or to be extracted.

During a second step referenced 42, the two claws 34, 35 of the clip 3 are shaped by standard folding at 90 °. A standard 90 ° bending of the two fingers 32, 33 of the clip 3 is then carried out (43), then a standard 45 ° folding (44) of the two support lines 311, 312 of the clip 3.

During a step referenced 45, the curved part 46 is shaped by the natural effect of the metal strip by bringing the ends of the clip 3 downwards. It is also possible to envisage an industrial manufacture of the clip 3, during which the steps referenced 44 and 45 are carried out at once by pressure using a tool of suitable shape.

When the clip 3 has been formed, it can be positioned on a module 1 which one wishes to extract by reflow from a motherboard 2, according to the method described in relation to FIG. 5. It can of course also be positioned on a plurality of components implanted on a first face of an application card in double reflow.

The components 1 are generally covered with a label 55, indicating a bar code, or a component reference for example. During a step referenced 51, it may be necessary, for thermal reasons, to remove this label 55. During a step referenced 52, a finger 33 (respectively 32) of the clip 3 is placed on the module 1 , making sure that the claw 35 (respectively 34) of the finger 33 (respectively 32) is correctly pressed on the printed circuit of the application card 2. By exerting (53) a lateral pressure P on the top of the already engaged finger 33, so as to isolate the other end of the clip 3 well, the second claw 34 is placed on the printed circuit of the application card 2. The lateral pressure exerted is illustrated in the form of arrow 56. It then suffices to remove (54) the pressure P and to release the other end of the clip 3.

Care is then taken to place (57) the clip 3 relative to the barycenter of module 1, if possible at a distance less than half the distance between the edge of module 1 and its barycenter, so that the preemption area 58 as close as possible to the barycenter. Indeed, the preemption zone 58 determines the surface on which a vacuum nozzle must take the module 1 during the extraction thereof from the application card 2. To increase the stability of the module 1 during its extraction by suction, it is recalled that it is important that the vacuum nozzle is positioned as close as possible to the barycenter of module 1.

Due to the presence of the convex part 46 of the clip 3, it may be preferable not to place the nozzle directly on the clip 3, but on the upper part of the module 1. It is of course also possible to place the suction pipette directly on the clip, and to position the latter at the barycenter of module 1, for example if provision is made for the design of a clip 3 having a preemption zone.

The method of positioning the clip on a module described in relation to FIG. 5 can of course be extended to positioning the clip on several components installed on the same face of a printed circuit, as illustrated in FIG. 8.

The intermediate part of the clip 3 then comes into contact with the upper part of the components 81, 82 and 83: one can for example envisage that such an intermediate part has a general shape in staircase steps, for example three steps, so that each of these three steps is in contact, at least on a pressure contact line, with the upper part of one of the three components 81, 82 and 83 on which the clip 3 is positioned. The claws 34, 35 of the clip 3 are then in contact with the underside of the printed circuit 80. The positioning of the retaining clip on one or more modules may well sure also to be automated, and performed by a suitable robot. Figures 6 and 7 show variants of mechanical holding clip 3 which can be used according to the invention.

FIGS. 6a and 6b respectively present a perspective view and a top view of a multi-socket clip, having a general shape of Y. Such a clip comprises an intermediate part 60 provided with a preemption zone 61 (for example a surface with a diameter greater than or equal to 7 mm). Three fingers 62, 63 and 64 extend substantially perpendicularly to the intermediate part 60, and each end in a claw 65, 66 and 67. The intermediate part has 6 pressure contact lines referenced 601 to 606.

FIG. 7 shows an example of a single point clip 70, having a single pressure contact line 71. Again, such a clip comprises an intermediate part 72, two fingers 73 and 74 extending substantially perpendicularly to the intermediate part 72, each of the fingers 73, 74 ending in a claw 75, 76 returning towards the inside of the clip 70. Such a single point clip 70 is particularly suitable for small components. It is of course also possible to envisage designing multi-socket clips without preemption zone, or clips of the type of clip 3 in FIG. 4 having a preemption zone.

The clips presented in relation to FIGS. 6 and 7 can be positioned on all types of components, and in particular on macro components, hybrid components and components mounted on the surface, during their installation on a printed circuit and / or during their extraction from this circuit. Such clips can also be positioned to ensure the maintenance of components, for example the maintenance of heavy components implanted on cards having components on their two faces, and thereby undergoing a double reflow.

Claims

1. Method for mounting and / or dismantling at least one electronic module (1) on an application card (2), said module comprising at least two constituent elements, namely at least one printed circuit (12) and at least one other constituent element mechanically connected by at least one solder to said printed circuit, said module further comprising a set of transfer elements by reflow of said module on an application card, characterized in that it implements a step of mechanical retention by spring effect of said constituent elements of said at least one module, so as to ensure mechanical cohesion during the remelting of said set of transfer elements for mounting and / or dismounting of said module on said card. application.

2. Method of manufacturing at least one electronic module comprising at least two constituent elements, namely at least one printed circuit having two faces, and at least one first other constituent element mechanically connected by at least one solder to a first face of said at least one printed circuit, characterized in that it comprises a step of mechanical maintenance by spring effect of said at least one first other component with said at least one printed circuit, during implantation by reflow of at least one second another constituent element on a second face of said at least one printed circuit.

3. Method according to any one of claims 1 and 2, characterized in that said electronic module (1) is a module for radiocommunication equipment comprising components (81, 82, 83) mounted on said at least one printed circuit ( 80) and ensuring at least one of the following functions: RF processing, digital processing and analog processing, so as to form a macro electronic component.

4. Method according to any one of claims 1 to 3, characterized in that said at least one other constituent element is an electronic component.

5. Method according to any one of claims 1 to 3, characterized in that said at least one other constituent element is a shielding cover (11) fixed by soldering on said at least one printed circuit (12).

6. Method according to any one of claims 1 to 3, characterized in that said at least one other constituent element is an interposing structure

(13) having a lower face and an upper face, said upper face being fixed by soldering on said at least one printed circuit

(12) and said lower face being fixed by soldering on said application card

(1) using said set of transfer elements.

7. Method according to any one of claims 1 to 3, characterized in that said module comprises at least the following three other constituent elements: a component, fixed by soldering on said printed circuit; a shielding cover, fixed by soldering on an upper face of said at least one printed circuit; an interposing structure having a lower face and an upper face, said upper face of said structure being fixed by soldering on a lower face of said printed circuit and said lower face of said structure being fixed by soldering on said application card to the using said set of transfer elements.

8. Method according to any one of claims 1 to 7, characterized in that said mechanical holding by spring effect is ensured by positioning a mechanical holding clip (3) on said at least one module (1).

9. Method according to claim 8, characterized in that said mechanical holding clip is positioned on at least two modules.

10. The method of claim 8, characterized in that said mechanical holding clip is positioned on or near the barycenter of said at least one module.

11. Method according to claim 10, characterized in that an upper part of said clip being of substantially rectilinear shape and having an axis longitudinal, said clip is positioned on said module so that said upper part is located between said barycenter of said module and an edge of said module substantially parallel to said longitudinal axis, so that the distance between said upper part and said barycenter is less than half the distance between said edge and said barycenter.

12. Disassembly method according to any one of claims 1 and 3 to 11, characterized in that it comprises steps of: positioning of said retaining clip on said module; placing said application card in a reflow device; - Local heating of said module until reflow of said transfer elements, using heating elements of said reflow device; positioning of extraction means in a preemption zone (61) of said predetermined module; extracting said module from said application card; - stopping said heating elements of said module; cooling of said module; recovery of said module on said extraction means.

13. Disassembly method according to claim 12, characterized in that it further comprises at least one of the steps belonging to the group comprising: - fluxing of at least certain peripheral pins of said module; preheating of said application card, using heating elements of said reflow device.

14. Disassembly method according to any one of claims 12 and 13, characterized in that said predetermined preemption zone (61) is located near said barycenter of said module.

15. Mechanical holding clip (3) of at least one electronic module comprising at least two constituent elements, namely at least one printed circuit and at least one other constituent element mechanically connected by at least one solder to said printed circuit, said module further comprising a set of transfer elements by reflow of said module on an application card, said retaining clip comprising means for ensuring the mechanical cohesion of said at least one module during the reflow of said set of transfer elements for mounting and / or dismantling said module on said application card.

16. Mechanical holding clip of at least one electronic module comprising at least two constituent elements, namely at least one printed circuit having two faces, and at least one first other constituent element mechanically connected by at least one solder to a first face of said printed circuit, said retaining clip comprising means making it possible to ensure the mechanical cohesion of said module during implantation by reflow of at least one second other constituent element on a second face of said at least one printed circuit.

17. Retaining clip according to any one of claims 15 and 16, characterized in that it comprises an intermediate part (31) and at least two fingers (32, 33) extending substantially perpendicular to said intermediate part, each said fingers ending in a claw (34, 35) returning towards the inside of said clip substantially parallel to said intermediate part.

18. retaining clip according to claim 17, characterized in that it is preformed so that, when positioned on said module, said claws come into contact with the lower part of said module.

19. retaining clip according to any one of claims 17 and 18, characterized in that said intermediate part has at least one line (311,

312) pressure contact intended to come into contact with the upper part of said module, when said clip is positioned on said module.

20. Holding clip according to any one of claims 17 to 19, characterized in that said intermediate part is substantially rectilinear, so that said clip has a general U shape.

21. retaining clip according to claim 20, characterized in that said intermediate part has two pressure contact lines, intended to come into contact with the upper part of said module, when said clip is positioned on said module.

22. Holding clip according to any one of claims 17 to 19, characterized in that said intermediate part has a general shape of Y, so that said clip has three fingers.

23. retaining clip according to any one of claims 17 to 22, characterized in that said intermediate part has a preemption surface (61), substantially coinciding with the barycenter of said module when said clip is positioned on said module.

24. Retaining clip according to any one of claims 16 to 23, characterized in that it is formed in a material which cannot be soldered to the tin / lead alloy (SnPb).

25. retaining clip according to any one of claims 16 to 24, characterized in that it has mechanical properties such that the pressure exerted by said clip on said module is greater than or equal to twice the weight of said module, when said clip is positioned on said module.

26. Retaining clip according to any one of claims 17 to 25, characterized in that it is preformed so as to detach from said module by pressing on one of said fingers.

27. retaining clip according to claim 15 and any one of claims 17 to 26, characterized in that, said transfer elements being of predetermined diameter D and being spaced from each other by a pitch P, the width of said claws is greater than or equal to the sum of said diameter D and said pitch P, and preferably to the sum of said diameter D and twice said pitch P.

28. Holding clip according to any one of claims 15 to 27, characterized in that it withstands a temperature at least equal to the reflow temperature without deterioration of its mechanical properties.

29. Retaining clip according to any one of claims 15 to 28, characterized in that it is intended to be positioned on at least two modules.

30. Mechanical holding clip according to claim 29, characterized in that said intermediate part has a shape complementary to that of said at least two modules on which said clip is intended to be positioned.

31. Mechanical retaining clip according to any one of claims 29 and 30, characterized in that said intermediate part has at least two contact lines by pressure, each of said lines coming to bear on one of said at least two modules, when said clip is positioned on said at least two modules.