EP1436773A1

EP1436773A1 - Electronic module with protective bump

Info

Publication number: EP1436773A1
Application number: EP02772720A
Authority: EP
Inventors: François Droz
Original assignee: NID SA
Current assignee: NID SA
Priority date: 2001-10-09
Filing date: 2002-10-08
Publication date: 2004-07-14
Also published as: US20040238210A1; WO2003032241A1

Abstract

The invention concerns an electronic module comprising an assembly consisting of a substrate, a conductive layer including a plurality of tracks and at least an electronic component. Said assembly forming an electronic circuit (1) is provided with at least a first component-free zone (A) and a second zone (B) where the electronic component (3) is located. Said circuit (1) is covered on at least one of its sides with an insulating layer (2) with globally uniform thickness. The electronic module is characterized in that the insulating layer (2) matches the first zone (A) and comprises in the second zone (B) at least a bump (4) obtained by pressing the insulating layer (2) with a plate (20) including a recess (4').

Description

ELECTRONIC MODULE WITH PROTECTION BOSS

The present invention relates to an electronic module comprising several superimposed layers and at least one electronic component, as well as to a method for manufacturing such a module.

The invention relates to modules produced by assembling several layers, namely a substrate, a conductive layer and at least one protective layer. These electronic modules are here cards, electronic labels, tickets or tokens. They include at least one generally flexible support, an antenna and an electronic component which is, in most cases, a chip. The electronic module according to the invention is found in many applications as a means of identifying people or objects, access control or payment.

The subject of the present invention concentrates particularly on modules comprising an insulating support, called substrate, generally flexible and of thin thickness on which applied a plurality of conductive tracks and / or a coil acting as antenna. An electronic component is connected to the circuit formed by the tracks of the conductive layer. This assembly, substrate, conductive layer and electronic component constitutes an electronic circuit. The latter is covered with an insulating layer on at least one face. This layer is used to protect the circuit against mechanical and chemical attack (corrosion).

It is known to those skilled in the art, modules comprising electronic circuits which are protected by means such as:

- coating in a resin, - application of insulating layers

- covering by a shell

The protection means described above provide uniform protection over the entire surface of the circuit, that is to say, a sensitive zone comprising critical components and connections is protected in the same way as an empty zone. The installation of these protections requires operations that are all the more delicate and expensive as the circuit to be protected is fragile. Indeed, the electronic components becoming more and more complex, they hardly support the stresses which they undergo during the assembly of the modules by rolling of several layers. These constraints are essentially mechanical (high pressure) and thermal (high temperatures). In addition, the manufacture of very large quantities of modules imposes costs as low as possible and a high speed of execution.

The object of the present invention is to obtain a very inexpensive electronic module while having high reliability whatever its field of application. This concerns in particular the protection of the electronic circuit integrated in the module by means of insulating layers.

The present invention also aims to propose a method of producing an electronic module with such protection.

This object is achieved by an electronic module comprising an assembly of a substrate, of a conductive layer comprising a plurality of tracks and at least one electronic component, said assembly constituting an electronic circuit is provided with a first area free of component and a second zone where the electronic component is located, said circuit is covered on at least one of its faces by an insulating layer of generally uniform thickness, characterized in that this insulating layer follows the first zone and comprises in the second zone at least one boss obtained by pressing the insulating layer by a plate having a depression.

The module according to the invention has a relief on at least one of its faces, generally above the electronic component. This relief or boss provides greater protection to the component compared to that offered in empty areas or areas that only have conductive tracks. The electronic components are generally mounted on the surface of the electronic circuit and concentrated in a defined area by creating a local allowance on the circuit. Certain applications require a module whose thickness must be reduced to the minimum over most of its surface in order to keep the greatest possible flexibility. This module is distinguishes by two well defined zones: a first zone, thin and extended which corresponds to a region of the electronic circuit without electronic component and a second thicker and smaller zone which forms a boss located at the place where the component (s) are located .

The module may include a marking hollowed out in the protective layer or a hollow zone reserved for subsequent marking by printing or by supplying a plate. The hollow parts can be located both on the boss of the component and on the surface surrounding the latter.

For example, electronic luggage tags have a large flexible surface for inscriptions. They include an electronic circuit comprising an antenna and a chip which is located near the edge of the label. Each side of the circuit is covered with a thin insulating protective layer. The chip which is mounted on the surface on the circuit forms an additional thickness. The protective layer which also covers the chip forms a relief which encompasses the contours of the chip on one of the faces of the label. This relief or boss does not disturb the use of the label which is hung on the luggage preferably by the side close to the relief. Indeed, the role of the label is limited to the identification of the baggage by radio (antenna and chip) and / or by visual way (marking of the surface).

The protective layer generally consists of a plastic film of constant thickness over its entire surface. This layer forms the boss which embraces the component without touching it. The free space under the boss, around the component is either filled with air, or filled with glue, trapped during the laminating of the protective layer.

In a variant of the module according to the invention, the component is surrounded by an overmolding or by a capsule before the laminating of the protective layer.

These different forms of filling the space between the component and the protective layer offer special protection to the component, while the other parts of the surface of the module are directly covered by the protective layer without any intermediate space. The present invention also relates to a method of manufacturing an electronic module by rolling between two pressing plates, comprising an assembly of a substrate, a conductive layer comprising a plurality of tracks and at least one electronic component, said assembly constituting an electronic circuit, and at least one planar insulating layer and of generally uniform thickness, characterized in that the assembly of the insulating layer on the face of the circuit comprising the electronic component is carried out by rolling by means of a plate comprising at least one depression vis-à-vis the zone where the electronic component is located on the circuit.

The method of manufacturing the module described above has the advantage of not damaging the electronic component during rolling. Indeed, the depression machined in the rolling plate located in front of the component has a sufficient depth to prevent the pressure of the plate on the component. This depression may be in the form of a hollow, the bottom of which is closed, or of a hole, the depth of which is defined by the thickness of the rolling plate. During rolling, under the effect of heat and pressure, the viscosity of the material of the protective layer is high. This softened material penetrates into the depression of the plate to form the relief above the component. The contour of this relief then takes the same form as that of the depression of the plate. The remaining part of the protective layer is laminated by direct pressure on the areas of the circuit devoid of component.

The protective layer can be hot rolled directly on the circuit. The material partially melts to adhere to the surface of the circuit. The depression of the rolling plate forms the boss on the electronic component. This boss is filled with air trapped during rolling.

During lamination, it is also possible to use hot-melt glue or resin by distributing an adhesive layer on the surface of the circuit. In this case, the glue, by melting, fills the relief including the electronic component. This filling further improves the protection of the component.

According to a variant of the method, the protective layer can be preformed before rolling on the electronic circuit. In this case a film of insulating material is preferably formed by hot pressing by means of a plate comprising at least one depression. Each depression of the plate forms a relief on the film of insulating material. A next step is to superimpose this preformed protective layer on the circuit by matching the bosses with the locations of the electronic components on the circuit. Laminating is then carried out with or without an adhesive layer, as described above.

According to another variant of the invention, a logo or other marking can be engraved in the depression of the rolling plate. The boss obtained on the protective layer will be provided with a relief marking corresponding to that engraved on the plate.

In general, any cavity, whatever its shape, hollowed out in the rolling plate creates corresponding reliefs on the protective layer of the module.

Conversely, any relief on the rolling plate creates hollows in the protective layer. This scenario is used for example to make a hollow on the boss intended to receive a marking plate. The rolling plates therefore have a hollow on the bottom of which is a relief corresponding to the shape of the plate to be inserted on the boss.

A frequent realization on electronic labels attached to a support consists in digging a groove in the protective layer around the boss including the electronic component or the chip. The rolling plate in this case has a recess for the boss and a relief around the latter for the groove. This groove forms a pre-cutting of the chip. Tearing off such a label from its support causes the circuit to be torn along the precut, which makes the label unusable.

The invention will be better understood thanks to the detailed description which follows and which refers to the appended drawings which are given by way of non-limiting example, in which:

- Figure 1 shows a top view of an electronic module with boss

- Figure 2 shows a section of an electronic module with a protective layer having a boss on one side. - Figure 3 shows a section of an electronic module with a protective layer having a boss on each side.

- Figure 4 shows a section of an electronic module with a protective layer comprising a boss on each side and an adhesive layer

- Figure 5 shows a section of an electronic module with a protective layer comprising a boss provided with a hollow

- Figure 6 shows a section of an electronic module with a protective layer comprising a boss and an additional cover.

- Figure 7 shows a section of an electronic module with a protective layer comprising a boss on an encapsulated component.

- Figure 8 shows a section of an electronic module with a protective layer comprising a boss with pre-cutting

FIG. 1 shows a view of the upper face of an electronic module which has two zones (A) and (B). The zone (A), devoid of electronic component, generally has a small thickness which corresponds approximately to that of the substrate of the electronic circuit (1) plus that of the insulating layer (2). The zone (B) forms a boss (4) covering an electronic component.

Figure 2 illustrates a section of the module of Figure 1 comprising an electronic circuit (1) on which is mounted an electronic component (3) and a protective layer (2). The area (B) where the electronic component (3) is located forms a boss (4) on the circuit (1) including the component (3). The space between the component (3) and the protective layer (2) is filled with the air trapped during the rolling of the protective layer (2) on the circuit (1).

The rolling plate (20) has a depression (4 ') whose contour corresponds to that of the boss (4). After the protective layer (2) has been superimposed on the circuit (1), the lamination is carried out by hot pressing (P) of the plate on the circuit and protective layer assembly. The plate is arranged so that the depression (4 ') is above the component (3), the material of the protective layer (2) penetrates into the depression (4') under the effect of the heat in creating a bubble which forms the boss (4). In most cases, the height of the boss (4) is less than the depth of the depression (4 ') of the plate (20). The latter plays a different role from that of a mold which creates a shape similar to the volume of a cavity. Here, the expansion of the air surrounding the component contributes to the formation of the boss (4) whose external surface does not necessarily come into contact with the internal surface of the depression (4 ') of the plate (20)

Tests have shown that the depression (4 ') can be replaced by a hole passing through the pressing plate (20). The boss (4) thus formed will have a contour corresponding to that of the hole and a height limited by the component (3) and the trapped air including the component.

FIG. 3 illustrates a module similar to that of FIG. 2 with a second protective layer (2) laminated on the second face of the electronic circuit (1). This layer also includes a boss (4) which protects the component (3) from below.

FIG. 4 represents the module of FIG. 3 where the protective layers (2) are laminated on each face by previously placing an adhesive layer (5) on the circuit. Glue, generally hot-meltable, fills the space between the electronic component (3) and the boss (4). The protection of the component (3) is thus better than that offered in FIG. 2 where the space is filled with air.

Figure 5 shows an embodiment of a relief (7) on the boss (4) which constitutes the edges of a hollow in which a plate (6) can be glued. The rolling plate (20) in this case comprises a cavity (4 ') at the bottom of which a groove (7') draws the outline of the hollow of the boss (4) where the plate (6) will be housed. In this case the depth and the shape of the cavity (4 ') is adapted to that of the boss (4) to be created on the protective layer (2) of the module.

FIG. 6 illustrates the module of FIG. 2 provided with an additional protective layer (8) around the boss (4). This layer is for example a personalization bag (8) which allows the printing of data specific to the carrier of the module. FIG. 7 shows an additional protection of the component (3) constituted by an overmolding or by a capsule (9) which is applied to the component before lamination of the protective layer (2).

FIG. 8 shows a pre-cutting (10) of the electronic component constituted by a groove (10) which surrounds all or part of the boss (4). The rolling plate (20) in this case has a relief (10 ') which surrounds the edge of the cavity (4') used to form the boss (4). The thickness of the module at the bottom of the groove (10) is close to that of the electronic circuit (1). This highly fragile area is permitted by certain applications where destruction of the module is required during a tear-off, for example.

Claims

1. Electronic module comprising an assembly of a substrate, of a conductive layer comprising a plurality of tracks and at least one electronic component (3), said assembly constituting an electronic circuit (1) is provided with a first area free of component (A) and a second zone (B) where the electronic component (3) is located, said circuit (1) is covered on at least one of its faces by an insulating layer (2) of generally uniform thickness, characterized in that this insulating layer (2) follows the first zone (A) and comprises in the second zone (B) at least one boss (4) obtained during the pressing of the insulating layer (2) by a plate (20) comprising a depression (4 ').

2. Electronic module according to claim 1, characterized in that the space between the electronic component (3) and the insulating layer (2) covering the boss (4) is filled with air.

3. Electronic module according to claim 1, comprising an adhesive layer (5) between the electronic circuit (1) and the insulating layer (2), characterized in that the adhesive layer (5) mainly fills the space between the electronic component (3) and the insulating layer (2) of the boss (4).

4. Electronic module according to claim 2, characterized in that the electronic component (3) placed under the boss (4) is protected by a capsule (9) -

5. Electronic module according to one of the preceding claims, characterized in that the boss (4) comprises a hollow area for receiving a marking (7) and / or an engraving (10).

6. Method of manufacturing an electronic module by rolling between two pressing plates, comprising an assembly of a substrate, of a conductive layer comprising a plurality of tracks and at least one electronic component, said assembly constituting an electronic circuit ( 1), and at least one insulating layer (2) planar and of generally uniform thickness, characterized in that the assembly of the insulating layer (2), on the face of the circuit comprising the electronic component (3), s' carried out by rolling by means of a plate (20) comprising at least one depression (4 ') with respect to the zone (B) where the electronic component (3) is located on the circuit (1).

7. Method of manufacturing an electronic module according to claim 6, characterized in that the rolling causes a deformation (4) of the insulating layer (2) around the component (3) under the effect of the pressure and the heat applied during rolling, said deformation creates a boss (4) of the same circumference as the depression (4 ') in the rolling plate (20).

8. Method of manufacturing an electronic module according to claim 7, characterized in that one and / or the other face of the electronic circuit (1) is covered with an adhesive layer (5) before the laminating of the insulating layer (2), said adhesive layer (5) penetrates, during rolling, in the space defined between the electronic component (3) and the boss (4) of the insulating layer (2)

9. Method of manufacturing an electronic module according to claim 6, characterized in that the rolling is carried out by means of plates comprising at least one relief, said relief deforms the insulating layer (2) by creating a hollow (7, 10 ) of the same shape as the relief on the rolling plate.

10. Method of manufacturing an electronic module according to claim 6, characterized in that at least one boss (4) on the insulating layer (2) is carried out in a first step and the assembly of said insulating layer (2 ) preformed on the electronic circuit (1) is produced in a second step by superimposing the boss (4) of the insulating layer (2) on the electronic component (3) of the circuit (1).