FR3144735A1 - Electronic module, electronic card and method of manufacturing an electronic module - Google Patents

Abstract

Electronic module, electronic card and method of manufacturing an electronic module An electronic module (10) comprises: - a printed circuit (12) having an upper face (26) and a lower face (28) opposite each other, the printed circuit (12) ) comprising a reference conductor, - electrical components (14A, 14B, 14C, 14D) mounted on the upper face (26) of the printed circuit (12), - a coating layer (16) arranged on the upper face ( 26) of the printed circuit (12) by coating the electrical components (14A, 14B, 14C, 14D), the coating layer (16) being made of a dielectric material, - a metal protective cage (18) covering the layer coating (16), and - at least one protective via (20), each protective via (20) connecting the protective cage (18) to the reference conductor by crossing the coating layer (16). Figure for abstract: Figure 2

Description

Electronic module, electronic card and method of manufacturing an electronic module

The present invention relates to an electronic module, an electronic card and a method of manufacturing an electronic module.

It is possible to integrate on an electronic card numerous heterogeneous electrical components usually distributed into functional zones, each zone grouping together the electrical components performing a particular function, such as a power supply function, a signal processing function, a function graphical control, graphical interface function, ...

It is possible to manufacture an electronic card by assembling one or more electronic modules on a printed circuit, each electronic module itself comprising a printed circuit on which electrical components are mounted. The electrical components of each electronic module can be divided into zones, each zone having a respective function.

This manufacturing method is called PCMA (Printed Circuit Module Assembly) technology.

This PCMA technology has the advantages of increasing the densification of areas, while using economical manufacturing techniques, even for low production volumes.

However, this strong densification of the zones leads to a strong proximity between the electrical components within the electronic module.

However, this proximity is particularly disadvantageous in the case where one of the zones of the electronic module emits electromagnetic disturbances likely to disturb a neighboring zone sensitive to electromagnetic disturbances.

This electromagnetic interference between areas of the electronic module potentially reduces the performance of the electronic module.

One of the aims of the invention is to overcome this drawback and to reduce electromagnetic interference between the zones of an electronic module.

For this purpose, the invention proposes an electronic module comprising:

- a printed circuit having an opposite upper face and a lower face, the printed circuit comprising a reference conductor,

- electrical components mounted on the upper face of the printed circuit,

- a coating layer placed on the upper face of the printed circuit by coating the electrical components, the coating layer being made of a dielectric material,

- a metal protective cage covering the coating layer, and

- at least one protective via, each protective via connecting the protective cage to the reference conductor by crossing the coating layer. According to particular implementation modes, the electronic module includes one or more of the following optional characteristics, taken individually or in all technically possible combinations:

- the electrical components include at least a third electrical component having a connection terminal electrically connected to the reference conductor, at least one or each protective via connecting the connection terminal of a third electrical component associated with this via to the cage of protection by crossing the coating layer;

- the third electrical component associated with one or each via is a passive electrical component, such as a resistive element, a capacitive element or an inductive element;

- one or each protective via is a metallized passage, preferably a metallized orifice, in particular a metallized orifice of circular cross section;

- each protective via has its transverse dimensions, taken perpendicular to a direction of extension of the protective via through the coating layer, comprised between 100 μm and 300 µm;

- the electronic module comprises at least one polluting zone likely to emit electromagnetic disturbances and a sensitive zone likely to be disturbed by electromagnetic disturbances, the module comprising a plurality of protection vias arranged so as to define an internal protective partition between the polluting zone and the sensitive zone;

- the printed circuit is laminated and comprises at least one insulating layer and at least one conductive layer, each insulating layer being made of a dielectric material and each conductive layer being made of an electrically conductive material;

- the reference conductive layer is configured to be at a reference electrical potential; And

- the metal protective cage is electrically connected to the reference conductive layer.

The invention also relates to an electronic card comprising at least one electronic module as described above.

The invention also relates to a method of manufacturing an electronic module, said method comprising the following steps:

- a step of drilling at least one passage passing through a coating layer made of a dielectric material and covering the upper face of a printed circuit on which electrical components are mounted, the coating layer coating the electrical components, And

- a step of depositing metal in each passage to form a protective via connecting a metal protective cage covering the coating layer to a reference conductor of the printed circuit by crossing the coating layer.

According to particular modes of implementation, the method includes one or more of the following optional characteristics, taken individually or in all technically possible combinations:

- the electrical components include at least a third electrical component having a connection terminal electrically connected to a reference conductor, at least one or each protective via connecting the connection terminal of a third electrical component associated with this via to the cage protection by crossing the coating layer;

- the method is implemented so as to form a plurality of protection vias arranged so as to define an internal protective partition between a polluting zone likely to emit electromagnetic disturbances and a sensitive zone likely to be disturbed by disturbances electromagnetic;

- the method comprises a step of assembling electrical components on an upper face of a printed circuit, the printed circuit being preferably laminated and comprising at least one insulating layer and at least one conductive layer, each insulating layer being produced in a dielectric material and each conductive layer being made of an electrically conductive material, a conductive layer defining the reference conductive layer configured to be at the same reference electrical potential as the system; And

- the method comprises a step of applying a coating layer to the upper face of the printed circuit by coating the electrical components, the coating layer being made of a dielectric material.

The invention and its advantages will be better understood on reading the description which follows, given solely by way of non-limiting example, and made with reference to the appended drawings, in which:

- there is a schematic top view of an electronic module according to the invention; And

- there is a cross-sectional view of the electronic module of the , according to II – II on the .

The electronic module 10 illustrated in Figures 1 and 2 is for example intended to be mounted on a printed circuit of an electronic card (not shown), possibly with one or more other electronic modules and/or one or more electrical components mounted directly on the printed circuit of the electronic card.

The electronic module 10 comprises a printed circuit 12, electrical components 14A, 14B, 14C, 14D, a coating layer 16, a metal protective cage 18 and at least one protective via 20, and preferably a plurality of vias protection 20.

For reasons of readability, the metal protective cage 18 and the coating layer 16 are not shown on the .

The electronic module 10 is for example configured to implement a plurality of individual functions, such as an audio function, a power supply function, a signal processing function, a graphic control function, or an interface function. chart.

The electrical components 14A, 14B, 14C, 14D are preferably grouped into distinct zones, each zone grouping together the associated electrical components 14A, 14B, 14C, 14D for the implementation of a specific function.

For this purpose, the electronic module 10 is for example divided into several functional zones 22, 24. Each functional zone 22, 24 corresponds to a function, i.e. groups together the elements and in particular electrical components performing together a function of the electronic module 10.

For example, the electrical components 14B, 14C, 14D are grouped in the same functional zone 24 to implement a function of the electronic module 10

In the example illustrated on the , the electronic module 10 comprises a first zone 22 and a second distinct functional zone 24 adjacent to each other, preferably corresponding to different functions. The first zone 22 corresponds for example to a power supply function. The second zone 24 corresponds for example to an audio signal processing function.

It is possible that a zone of the electronic module 10, subsequently qualified as "polluting", is likely to emit electromagnetic disturbances, and that another zone of the electronic module 10, subsequently qualified as "sensitive" is likely to see its operation disrupted by electromagnetic disturbances emitted by the polluting zone.

A polluting zone includes for example one or more 14A electrical components, hereinafter described as “pollutants”, capable of emitting electromagnetic waves.

A sensitive zone includes for example one or more electrical components 14B, hereinafter described as “sensitive”, capable of capturing electromagnetic waves.

In one example, the first zone 22 is a polluting zone likely to emit electromagnetic disturbances and the second zone 24 is a sensitive zone likely to be disturbed by electromagnetic disturbances, and in particular by those emitted by the first zone 22.

The printed circuit 12 has an upper face 26 and a lower face 28 opposite each other.

As illustrated on the , the printed circuit 12 is preferably laminated and comprises a plurality of layers stacked on top of each other, in particular between the upper face 26 and the lower face 28.

More particularly, the printed circuit 12 comprises at least one insulating layer 30 and at least one conductive layer 32, and advantageously an alternation of insulating layers 30 and conductive layers 32, 34.

In the example illustrated on the , the printed circuit 12 comprises five insulating layers 30 and four conductive layers 32, 34. The conductive layers 32, 34 are for example interposed between the insulating layers 30. Preferably, each conductive layer 32, 34 is interposed between two insulating layers 30

Preferably, each insulating layer 30 is made of a dielectric material, such as for example a matrix of plastic or resin material, possibly reinforced with fibers, for example glass fibers. A material comprising a resin matrix reinforced with glass fibers is known under the designation FR4.

Preferably, each conductive layer 32,34 is made of an electrically conductive material, such as for example a metallic material, in particular copper or a copper alloy.

The printed circuit 12 comprises a reference conductor intended to be connected to a reference electrical potential. Such a reference conductor is for example connected to the electrical ground.

In an example embodiment, the reference conductor is one of the conductive layers 32, 34, subsequently called reference conductive layer 34.

In the example illustrated on the , the reference conductive layer 34 corresponds for example to the third conductive layer of the printed circuit 12 starting from the upper face 26.

The reference conductive layer 34 is advantageously configured to be brought to a reference electrical potential, preferably being connected to the electrical ground.

The printed circuit 12 optionally includes connection pads 35 arranged under the lower face 28 and/or on the upper face 26.

The connection pads 35 under the lower face 28 are for example intended to be connected to connection pads of a printed circuit of an electronic card when mounting the electronic module 10 on said printed circuit or to connection pads of another electronic module for mounting the electronic module 10 on said other electronic module.

The connection pads 35 on the upper face 26 are for example intended to be connected to electrical components 14A, 14B, 14C, 14D.

The printed circuit 12 also advantageously comprises connecting vias 36, each connecting via 36 being electrically conductive and extending between at least two of the conductive layers 32, 34 to electrically connect them to each other or between at least one of the conductive layers 32 , 34 and one or more connection pads 35 to connect them electrically.

The electrical components 14A, 14B, 14C, 14D are mounted on the upper face 26 of the printed circuit 12, preferably by soldering.

As illustrated on the , each electrical component 14A, 14B, 14C, 14D comprises for example a main body 38 and at least one connection terminal 40 for connecting the electrical component 14A, 14B, 14C, 14D to the printed circuit 12. Each electrical component 14A, 14B, 14C, 14D preferably comprises at least two connection terminals 40.

Each electrical component 14A, 14B, 14C, 14D is advantageously chosen from a passive electrical component, an active electrical component, a component comprising an integrated circuit or an electromechanical microsystem.

Electrical components 14A, 14B, 14C, 14D are more particularly arranged on the printed circuit 12 in each of the first zone 22 and the second zone 24 in order to carry out the corresponding function.

In particular, the electrical components 14A, 14B, 14C, 14D include for example at least one polluting component 14A emitting electromagnetic disturbances arranged in the first zone 22 (polluting zone).

For example, the polluting component 14A emits low-frequency electromagnetic waves, for example with a frequency between 200 kHz and 2 MHz.

The polluting component 14A is for example an unshielded inductor.

Likewise, the electrical components 14A, 14B, 14C, 14D include for example at least one sensitive component 14B arranged in the second zone 24 (sensitive zone) likely to be disturbed by electromagnetic disturbances, and in particular by those emitted by the or the polluting components 14A of the first zone 22.

The sensitive component 14B is for example another inductor whose magnetic field couples with that of the inductance of the component 14A.

The coating layer 16 is placed on the upper face 26 of the printed circuit 12 by coating the electrical components 14A, 14B, 14C, 14D.

The coating layer 16 is preferably made of a dielectric material.

For example, the coating layer 16 is made of resin, in particular of epoxy type resin.

The coating layer 16 has for example a thickness, measured in a direction of extension Z, of between 2.mm and 5 mm. The extension direction Z is preferably normal to the extension plane along which the upper face of the printed circuit 12 extends.

As illustrated on the , the metal protective cage 18 covers the coating layer 16.

Advantageously, the metal protective cage 18 also covers at least partially the side faces of the printed circuit 12.

In particular, the metal protective cage 18 comprises an upper face 42 extending over the coating layer 16 and side portions 44 covering side faces of the coating layer 16 and preferably extending downwards to 'to cover at least partially the side faces of the printed circuit 12.

Preferably, the metal protective cage 18 is electrically connected to the reference conductor, in particular to the reference conductive layer 34, in particular at the level of the side faces of the printed circuit 12.

In particular, advantageously the reference conductor, in particular the reference conductive layer 34, is flush with one or more side faces of the printed circuit 12 and/or projects from one or more side faces of the printed circuit 12 while being electrically connected to the cage protection 18.

The metal protective cage 18 has, for example, a thickness of between 5 μm and 50 μm.

The metal protective cage 18 makes it possible in particular to protect the electrical components 14A, 14B, 14C, 14D against moisture infiltration and to provide electromagnetic shielding of the electronic module 10 as a whole, for example against electromagnetic disturbances. external.

As illustrated on the , each protective via 20 connects the protective cage 18 to the reference conductor, in particular to the reference conductive layer 34, by crossing the coating layer 16 and, preferably by connecting to the terminal 40 of a component 14C itself connected to the reference potential as will be specified below.

Preferably, the electrical components 14A, 14B, 14C, 14D include at least a third electrical component 14C having a connection terminal 40 electrically connected to the reference conductor, in particular to the reference conductive layer 34, for example by an electrically via driver 48.

Advantageously, at least one or each protective via 20 connects the connection terminal 40 of one of the third electrical components 14C associated with this via 20 to the protective cage 18 by crossing the coating layer 16.

Each third electrical component 14C associated with one or each protection via 20 is for example a passive electrical component, such as a resistive element such as a resistor, a capacitive element such as a capacitor or an inductive element such as a coil.

Advantageously, each third electrical component 14C is arranged in the second zone 24 (sensitive zone), preferably at the border with the first zone 22 (polluting zone).

Preferably, as is visible in the exemplary embodiment illustrated on the , the third electrical components 14C are arranged next to each other along the border between the first zone 22 and the second zone 24.

Each protective via 20 advantageously extends inside the coating layer 16, and in particular away from the lateral portions of said coating layer 16.

In other words, each protection via 20 is for example delimited laterally by the coating layer 16 extending all around the protection via 20. Preferably, one or each protection via 20 is a metallized passage, preferably an orifice metallized, in particular a metallized orifice of circular cross section.

Each protection via 20 extends for example in the coating layer 16 in the direction of extension Z.

In particular, each protective via 20 extends between the upper face 42 of the protective cage 18 and the connection terminal 40 of the third electrical component 14C associated with this via 20.

More particularly, each protective via 20 has its transverse dimensions, taken perpendicular to the direction of extension Z through the coating layer 16, between 100 μm and 300 μm, and preferably between 100 μm and 250 μm.

In the case where the protective via 20 is a metallized orifice of circular cross section, the transverse dimension corresponds to the diameter of the circular section.

In the exemplary embodiment illustrated on the , several separate protective vias 20 are formed and arranged so as to define an internal protective partition 50, for example between the polluting zone 22 and the sensitive zone 24.

In particular, the internal protective partition 50 is defined by the arrangement of the protective vias 20 next to each other.

In the exemplary embodiment illustrated on the , the internal protective partition 50 is formed of several separate vias 20 distributed along a line being spaced apart from each other along said line.

For example, via 20 are spaced at a distance between 120 µm and 1 mm.

The formation of the internal protective partition 50 by the arrangement of several separate via 20 facilitates its manufacture, since each via 20 is manufactured individually, for example by mechanical or laser drilling.

The internal protective partition 50 makes it possible to limit the passage of electromagnetic waves emitted from the polluting zone 22 to the sensitive zone 24, in particular so as to protect the sensitive component 14B.

In particular, the closer the protection vias 20 are to each other, the denser the internal protective partition 50 is and the more the passage of electromagnetic waves is blocked, in particular for high frequencies.

The internal protective partition 50, seen from above, is for example substantially rectilinear as illustrated in the .

Alternatively, the internal protective partition 50 has a different shape, for example along a curvilinear line or a line having one or more curvilinear sections and/or one or more rectilinear sections.

The internal protective partition 50 extends for example between two distinct ends as is illustrated in the .

Alternatively, the internal protective partition 50 extends along a closed line. In this case, it surrounds, for example, a sensitive area or a polluting area.

Alternatively or optionally, at least one via 20 is elongated to form a continuous partition or a portion of a continuous partition.

In operation, the polluting zone 22, and in particular the polluting component 14A emits electromagnetic waves in all directions, and in particular towards the sensitive zone 24. The internal protective partition 50 formed by the via(s) 20 blocks at least partially the electromagnetic waves emitted towards the sensitive zone 24. Only part of the electromagnetic waves therefore reaches the sensitive component 14B, which is therefore little disturbed by them.

A method of manufacturing such an electronic module 10 will now be described.

The method preferably comprises a first step of assembling the electrical components 14A, 14B, 14C, 14D on the printed circuit 12, and in particular on its upper face 26.

Preferably, during this first assembly step, the electrical components 14A, 14B, 14C, 14D are more particularly arranged by zones 22, 24 each corresponding to an individual function.

Advantageously, during this first assembly step, the electrical components 14A, 14B, 14C, 14D are mounted on the upper face 26 of the printed circuit 12 according to CMS technology (acronym for “Component Mounted Surface” meaning mounted component). surface).

More particularly, the electrical components 14A, 14B, 14C, 14D are brazed to the surface of the printed circuit 12.

Advantageously, during this first assembly step, a connection terminal 40 of at least one of the electrical components 14A, 14B, 14C, 14D (hereinafter referred to as the third electrical component 14C) is electrically connected to the reference conductor, in particular to the reference conductive layer 34 of the printed circuit 12.

Preferably, the method comprises a step of applying the coating layer 16 placed on the upper face 26 of the printed circuit 12 by coating the electrical components 14A, 14B, 14C, 14D.

For example, this application step is carried out by spraying a dielectric material, such as resin for example.

The method comprises a step of drilling at least one passage 52 in said coating layer 16.

Preferably, the method comprises a step of drilling a plurality of passages 52 in said coating layer 16.

This step is more particularly implemented so as to form a plurality of passages 52 arranged between the polluting zone 22 and the sensitive zone 24.

Advantageously, at least one or each passage 52 extends between an upper face of the coating layer 16 and the connection terminal 40 of one of the third electrical components 14C connected to the reference conductor, in particular to the conductive layer of reference 34 of printed circuit 12.

The drilling of the passage(s) 52 is carried out by laser drilling.

The method then comprises a step of depositing metal in each passage 52 to form a protective via 20 connecting the metal protective cage 18 covering the coating layer 16 to the reference conductor, in particular to the reference conductive layer 34 of the printed circuit 12, passing through the coating layer 16.

Preferably, the metal protective cage 18 is also formed during this metal deposition step.

Advantageously, at least one or each protective via 20 connects the connection terminal 40 of one of the third electrical components 14C associated with this via 20 to the protective cage 18, in particular to the upper face 42 thereof, crossing the coating layer 16.

This step is preferably implemented so as to form a plurality of protective vias 20 arranged so as to define the internal protective partition 50 between the polluting zone 22 and the sensitive zone 24.

Preferably, the method then comprises a step of marking, testing and/or conditioning the electronic module 10.

The marking includes for example a polarity indicator, a product reference and a batch reference.

The electronic module 10 according to the invention is particularly advantageous, in that the protection vias 20, and more particularly the internal partition 50, limit the electromagnetic disturbances of the sensitive zone 24 by the polluting zone 22.

For example, such an internal protective partition 50 attenuates electromagnetic interference between the two zones 22, 24 by a factor of at least 100 for a frequency band of 100 Hz to 15 GHz.

Furthermore, the connection of the protection vias 20 to the connection terminals 40 of one of the third electrical components 14C makes it possible not to allocate additional space to the formation of this internal protective partition 50, and therefore not to reduce the densification of the electronic module 10.

In addition, each metal protection via 20 advantageously allows heat to be evacuated from the third electrical component 14C associated by the protection cage 18.

The electronic module 10 provided with protective via 20 can be easily manufactured, by providing, for each via 20, a passage 52 passing through the coating layer 16 before metallization to produce the protective cage 18.

Each passage 52 is easily created by digging or machining the coating layer 16, for example mechanically or by laser.

The connection of each via 20 to a connection terminal 40 of an electrical component 14C, in particular a passive electrical component, makes it possible to easily form the via 20 by digging the coating layer up to the terminal 40, which can be produced reliably and controlled, in particular by laser machining, limiting any risk of damaging the printed circuit 12 and/or the electrical components 14A, 14B, 14C, 14D.

The invention is not limited to the exemplary embodiments and variants discussed above. Other examples of implementation and other variants are possible.

For example, as a variant, the electronic module 10 is not divided into two functional zones 22, 24, but into a number of functional zones greater than or equal to three.

Furthermore, as a variant, the electronic module 10 does not only include a polluting zone 22, but at least two polluting zones.

Likewise, as a variant, the electronic module 10 does not only include a sensitive zone 24, but at least two sensitive zones.

According to another variant, the printed circuit 12 comprises a number of conductive layers 32 different from four. For example, the printed circuit 12 comprises a single conductive layer 32 or a number of conductive layers 32 of between two and four or greater than four.

In a particular mode of implementation, several electronic modules 10 are manufactured simultaneously on the same printed circuit board grouping together several printed circuits 12 initially integral, by the process as described above, this mode of implementation comprising the separation printed circuits 12.

In particular, in this mode of implementation, the method comprises, before the metal deposition step, a step of sawing passages extending between the upper face of the coating layer 16 and the reference layer 34 printed circuits 12. Each passage defines a boundary between two adjacent electronic modules 10.

Furthermore, the method comprises, following the metal deposition step, a step of separating the plurality of electronic modules 10 thus formed, preferably by sawing the passages up to the lower face 28 of each of the printed circuits 12. We thus obtain a plurality of electronic modules 10 separated from each other.

Claims (10)

Electronic module (10) comprising:

• a printed circuit (12) having an upper face (26) and a lower face (28) opposite each other, the printed circuit (12) comprising a reference conductor,
• electrical components (14A, 14B, 14C, 14D) mounted on the upper face (26) of the printed circuit (12),
• a coating layer (16) arranged on the upper face (26) of the printed circuit (12) by coating the electrical components (14A, 14B, 14C, 14D), the coating layer (16) being made of a material dielectric,
• a metal protective cage (18) covering the coating layer (16), and
• at least one protective via (20), each protective via (20) connecting the protective cage (18) to the reference conductor by crossing the coating layer (16).

Electronic module (10) according to claim 1, in which the electrical components (14A, 14B, 14C, 14D) include at least a third electrical component (14C) having a connection terminal (40) electrically connected to the reference conductor, to the at least one or each protective via (20) connecting the connection terminal (40) of a third electrical component (14C) associated with this via (20) to the protective cage (18) by crossing the coating layer ( 16). Electronic module (10) according to claim 2, in which the third electrical component (14C) associated with one or each via (20) is a passive electrical component, such as a resistive element, a capacitive element or an inductive element. Electronic module (10) according to any one of the preceding claims, in which one or each protection via (20) is a metallized passage, preferably a metallized orifice, in particular a metallized orifice of circular cross section. Electronic module (10) according to any one of the preceding claims, in which each protection via (20) has its transverse dimensions, taken perpendicular to a direction of extension (Z) of the protection via (20) through the coating layer (16), between 100 μm and 300 μm. Electronic module (10) according to any one of the preceding claims, comprising at least one polluting zone (22) capable of emitting electromagnetic disturbances and a sensitive zone (24) capable of being disturbed by electromagnetic disturbances, the module ( 10) comprising a plurality of protective vias (20) arranged so as to define an internal protective partition (50) between the polluting zone (22) and the sensitive zone (24). Electronic card comprising at least one electronic module (10) according to any one of the preceding claims. Method of manufacturing an electronic module (10), said method comprising the following steps:
- a step of drilling at least one passage (52) passing through a coating layer (16) made of a dielectric material and covering the upper face (26) of a printed circuit (12) on which components are mounted electrical components (14A, 14B, 14C, 14D), the coating layer (16) coating the electrical components (14A, 14B, 14C, 14D), and
- a step of depositing metal in each passage (52) to form a protective via (20) connecting a metal protective cage (18) covering the coating layer (16) to a reference conductor of the printed circuit ( 12) passing through the coating layer (16). Manufacturing method according to claim 8, the electrical components (14A, 14B, 14C, 14D) include at least a third electrical component (14C) having a connection terminal (40) electrically connected to a reference conductor, at least one or each protective via (20) connecting the connection terminal (40) of a third electrical component (14C) associated with this via (20) to the protective cage (18) by crossing the coating layer (16). Manufacturing method according to claim 8 or 9, implemented so as to form a plurality of protective vias (20) arranged so as to define an internal protective partition (50) between a polluting zone (22) capable of emitting electromagnetic disturbances and a sensitive area (24) likely to be disturbed by electromagnetic disturbances.