Protection device for integrated circuit and method of manufacturing such a module

Abstract

The invention relates to a device for protecting against an attack on an electronic component (IC) implanted on a printed circuit board (BD), the protection device (PM) comprising: a multilayer printed circuit board comprising upper layers and lower layers, the lower layers being machined to form two pillars (S1, S2) of a bridge, the pillars delimiting between them and with a lower face (LF) of the upper layers a volume configured to house the component, the pillars having a height such that the lower face delimits an empty space with an upper face of the component when the component and the protection device arranged above the component are fixed on the printed circuit board (BD), and conductive tracks formed in the upper and lower layers and connecting together connection elements of the protection device formed in a lower conductive layer of each of the pillars.Figure 2.

Description

Title of the invention: Protection device for integrated circuit and method of manufacturing such a module Technical field

[0001] The present invention relates to the protection of a component such as an integrated circuit, installed on a printed circuit. The present invention applies in particular to payment terminals integrating a bank card reader. State of the art

[0002] Certain parts of a payment terminal need to be protected against attacks aimed at recovering sensitive data such as bank card numbers entered or in wireless communication with the payment terminal, or even data or cryptographic programs stored or executed by the terminal.

[0003] For this purpose, it has already been proposed to arrange around a part to be protected shields or casings formed of printed circuits, to act as a barrier to attempts to insert probes or spy devices. The printed circuits forming the protection can be soldered onto a printed circuit board supporting the parts to be protected. The parts to be protected can be, for example, a group of components on a printed circuit, a magnetic reading head, or even a smart card connector.

[0004] To protect a component such as a connector, it is known to arrange above the connector a protection card fixed on one side in a cantilevered manner or on two adjacent sides. The card may comprise several layers on top of the component to be protected and vias in the part fixed to the printed circuit board supporting the connector. This solution is not satisfactory because it leaves certain faces of the connector accessible, and is insufficiently stable due to the cantilevered fixing.

[0005] It is also known to have a flexible printed circuit, stamped to completely cover the component to be protected, the flexible printed circuit being fixed to the printed circuit board on which the component is soldered. This solution is not satisfactory from a safety point of view, because the flexible printed circuit can be lifted by deforming it. The flexible printed circuit can also raise problems of evacuation of the heat released by the component. In addition, the fixing of the flexible printed circuit requires a relatively large space on the printed circuit board around the component to be protected.

[0006] Furthermore, the "bunker" or "compact vault" type security envelopes produced Using flexible printed circuits on a rigid or flexible support, they are suitable for protecting multiple components on a printed circuit board. Thus, they are very bulky and hardly suitable for protecting a single integrated component.

[0007] It is therefore desirable to provide compact and effective protection against intrusions to protect an integrated component soldered onto a printed circuit board. It may also be desirable for this protection not to prevent the evacuation of heat released by the component. Summary

[0008] Embodiments relate to a protection device for protecting an electronic component implanted on a printed circuit board against an attack, the protection device comprising: a multilayer printed circuit board comprising upper layers and lower layers, the lower layers being machined to form two pillars of a bridge, the pillars delimiting between them and with a lower face of the upper layers a volume configured to house the component to be protected, the pillars having a height such that the lower face delimits an empty space with an upper face of the component to be protected when the component to be protected and the protection device arranged above the component to be protected are fixed on the printed circuit board,and conductive tracks formed in the upper and lower layers and connecting together connection elements of the protection device formed in a lower conductive layer of each of the pillars.

[0009] In this way, the protection device can have a reduced footprint with a surface area slightly larger than that of the component to be protected and the two pillars do not need to cover a relatively large surface area. The protection device can be fixed to a printed circuit board without having a cantilever element. In addition, such a protection device can have a reduced cost due to the fact that it can be manufactured simply by using conventional multi-layer printed circuit manufacturing techniques and a simple machining operation to form the bridge. Furthermore, by being open on two sides and without coming into contact with the component to be protected, the protection device does not prevent the dissipation of heat likely to be released by the component, while still providing effective protection.

[0010] According to one embodiment, the lower layers form a third pillar partially closing an opening of the bridge.

[0011] Thus, the protection device is easily adaptable to the situation of the component to be protected in relation to the other components located on the printed circuit board. If one of the openings of the bridge shape of the protection device offers a possibility of attacking the component, it is easy to provide a third pillar for at least partially hide this opening.

[0012] According to one embodiment, the upper layers comprise a first lattice layer comprising at least two separate conductive tracks, nested one inside the other and together covering at least 80% of the upper surface of the upper layers, each conductive track comprising two ends connected respectively to two of the connection elements in the lower conductive layer of the pillars.

[0013] Thanks to these arrangements, the mesh layer allows a detection circuit connected to the connection elements to detect a piercing of the upper layers causing a cut or a short-circuiting of the conductive tracks forming the mesh.

[0014] According to one embodiment, the upper layers comprise a second lattice layer comprising at least two separate conductive tracks, nested one inside the other and arranged so that the spaces between the two conductive tracks are located opposite one of the tracks formed on the first lattice layer, each conductive track comprising two ends connected respectively to two of the connection elements in the lower conductive layer of the pillars.

[0015] The combination of two mesh layers offers additional possibilities for detecting a piercing of the upper layers by cutting a conductive track of this other mesh layer, and by short-circuiting a conductive track of one of the mesh layers with a conductive track of the other mesh layer.

[0016] According to one embodiment, the upper layers comprise a fully conductive ground layer, separated from the mesh layer by an insulating layer, and connected to connection elements in the lower conductive layer of the pillars.

[0017] The combination of a ground layer with another conductive layer offers an additional possibility of detecting a piercing of the upper layers by short-circuiting the ground layer with this other conductive layer.

[0018] According to one embodiment, the ground layer is connected to a connection element in the lower conductive layer of the pillars by a via passing through all the other layers located between the ground layer and the lower conductive layer of the pillars.

[0019] According to one embodiment, the lower layers comprise several intermediate conductive layers separated from each other, from the lower conductive layer and from the upper layers, by insulating layers, the intermediate conductive layers comprising conductive tracks connected to each other, with conductive tracks of the upper layers and with the connection elements of the lower layer, by vias.

[0020] This multilayer structure with conductive tracks formed in layers conductive and vias also allows the detection of a pillar piercing by a detection circuit connected to the protection device. Indeed, it is very likely that such a piercing will cause a break or short-circuit of a conductive track or a via.

[0021] Embodiments may also relate to a method of manufacturing a protection device for protecting an electronic component against an attack, the manufacturing method comprising steps of: manufacturing a multilayer printed circuit board comprising upper layers and lower layers, connection elements formed in lateral portions of a lower conductive layer, and conductive tracks formed in the upper layers and in lateral portions of the lower layers and connecting the connection elements together, machining the lower layers to form two pillars of a bridge with the lateral portions of the lower layers, so as to create an empty volume delimited by the pillars and a lower face of the upper layers, the empty volume having a determined extent to accommodate the component to be protected,the pillars having a height determined so that the lower face of the upper layers delimits an empty space with an upper face of the component to be protected, when the component to be protected and the protection device arranged above the component to be protected are fixed on a printed circuit board.

[0022] These manufacturing steps prove to be simple and inexpensive and make it possible to obtain a particularly compact protection device.

[0023] According to one embodiment, the protection device is as previously defined.

[0024] Embodiments may also relate to a method for protecting an electronic component implanted on a printed circuit board, the method comprising steps consisting of: obtaining a protection device as previously defined, the protection device being configured to cover the component to be protected while leaving an empty space between an upper face of the component to be protected and a lower face of the protection device when the protection device is arranged above the component to be protected;and fixing the protective device on the printed circuit board, covering the component to be protected, the connection elements of the protective device being connected to a detection circuit installed on the printed circuit board, the detection circuit being configured to detect a break in one of the conductive tracks formed in the protective device or a short circuit between two of the conductive tracks formed in the protective device. ;

[0025] According to one embodiment, the protection device is fixed on the printed circuit board in the same way as the component to be protected, by soldering connection pads of the protection device.

[0026] According to one embodiment, the protection device is fixed on the printed circuit board at the same time as the component to be protected.

[0027] Embodiments may also relate to a payment terminal comprising a sensitive electronic component implanted on a printed circuit board, and a protection device as previously defined, the protection device being fixed on the printed circuit board so as to cover a component to be protected and connected to a detection circuit formed on or in the printed circuit board and configured to detect a short circuit or a break in one of the conductive tracks in the protection device. Brief description of the figures

[0028] The present invention will be better understood with the aid of the following description of exemplary embodiments with reference to the appended figures, in which identical reference signs correspond to structurally and / or functionally identical or similar elements.

[0029] [Fig.l] Figure 1 schematically represents in front perspective, a part of a printed circuit board comprising a component covered with a protective device, according to one embodiment,

[0030] [Fig.2] Figure 2 is a schematic sectional view of the protection device and the component, according to one embodiment,

[0031] [Fig.3] Figure 3 is a schematic perspective view from below of the protection device, according to one embodiment,

[0032] [Fig.4] Figure 4 is a schematic sectional view of the protection device, according to one embodiment,

[0033] [Fig.5] Figure 5 schematically represents a part of a layer of the protection device, according to another embodiment,

[0034] [Fig.6] Figure 6 is a schematic perspective view from below of the protection device, according to another embodiment. Detailed description

[0035] Figure 1 shows a part of a printed circuit board BD installed in a payment terminal. The printed circuit board BD supports an electronic component IC to be protected on which it is soldered, a shielding plate C1 covering a part of the board BD, and a protection board C2 of a connector. The component IC can be for example an integrated circuit or a connector.

[0036] According to one embodiment, the IC component is covered with a protection device PM which is also soldered onto the printed circuit board BD.

[0037] Figures 2 and 3 show the PM protection device in more detail. The The PM protection device comprises a top plate UL integral with two side parts SI, S2 forming pillars. Thus, the PM protection device forms a bridge above the IC component to be protected with two openings on opposite faces of the protection device. In the configuration of the printed circuit board BD shown in Figure 1, the bridge shape of the PM protection device does not reduce the extent of protection of the IC component since the adjacent elements Cl, C2, namely the shielding plate Cl and the protection board C2 prevent access to the IC component through the openings of the PM protection device.

[0038] The upper plate UL has a lower face LF facing the component IC. According to one embodiment, the pillars SI, S2 have a height such that a space is provided between the upper face of the component IC and the lower face LF of the upper plate UL. In this way, the heat released by the component IC can be evacuated above the latter and through the openings of the protection device PM.

[0039] The lower face of the pillars SI, S2 comprises connection pads CP to be soldered onto connection pads of the printed circuit board BD to connect the protection device PM to a detection circuit DTC making it possible to detect a possible attack on the protection device PM, for example by tearing, drilling, rolling of the latter. The connection pads CP are connected to internal circuits of the protection device PM.

[0040] The PM protection device can thus easily be fixed on the printed circuit board BD using the same soldering technique as the IC component to be protected. According to one embodiment, the soldering of the PM protection device and the soldering of the IC component on the printed circuit board BD are carried out at the same time. The soldering technique used for this purpose may be the SMT ("Surface Mount Technology") surface mounting technique.

[0041] According to one embodiment, the PM protection device is made in a multilayer printed circuit board with vias connecting together some of the layers of the printed circuit board. The bridge shape of the PM protection device is made by machining the multilayer printed circuit board having the thickness of the pillars S1, S2, by removing the part in which the IC component is housed.

[0042] Figure 4 shows the multilayer structure of the PM protection device according to an exemplary embodiment. The multilayer structure shown in Figure 4 comprises eleven layers, including six electrically conductive layers CL1 to CL6 and five electrically insulating layers IL1 to IL5. Layers CL4, IL4, CL5, IL5 and CL6 cover the entire surface of the protection device, and therefore form the upper plate UL. Layers CL1 to IL3 are only present in pillars S1, S2 and have been removed from a central part of the printed circuit board by machining. Thus, the assembly formed by the layers CL1, IL1, CL2, IL2, CL3, IL3 has a thickness greater than the height of the IC component above the printed circuit board BD.

[0043] The layers CL4, CL5 and CL6 may comprise a ground layer (for example the layer CL6) comprising a conductive part covering the entire surface of the protection device PM, and two layers forming lattices (for example CL4 and CL5). The ground layer may be connected by a respective via V16 to a connection pad CP formed in the layer CL1 in each of the pillars SI, S2. Thus, the via V16 crosses all the layers of the multilayer plate between the layer CL1 and the layer CL6.

[0044] Figure 5 represents a part of one of the conductive layers CL4, CL5, according to one embodiment. As illustrated by Figure 5, each layer CL4, CL5 forming a lattice may comprise several conductive tracks PI, P2 nested one inside the other, not electrically connected to each other, following a labyrinth path that can be defined randomly, and covering the majority (at least 80%) of the surface of the protection device PM. The conductive tracks PI, P2 formed on the layers CL4, CL5 may be arranged so that the spaces between the conductive tracks formed on one of the layers CL4, CL5 are located opposite one of the tracks formed on the other of the layers CL4, CL5.

[0045] Each of the tracks PI, P2 of the layers CL4, CL5 forming a lattice is electrically connected by vias V12, V23, V34, V45 formed through the layers forming each of the pillars SI, S2 and the conductive tracks of conductive layers forming each of the pillars, to two of the connection pads CP formed on the pillars.

[0046] In this way, it is possible, using the DTC detection circuit formed in the BD board and connected to the connection pads, to detect a short circuit between the ground layer and one of the nested conductive tracks PI, P2 formed in one of the mesh layers, or a short circuit between two meshes formed in the same layer or two adjacent layers. It is also possible to detect a break in one of the conductive tracks forming one of the meshes of the layers C4, C5. Thus, an appropriate form of mesh, for example in the layers CL4 and CL5, can prevent any attempt to pierce the upper plate UL, by preventing the DTC detection circuit connected to the connection pads of the BD board from detecting a short circuit between the different conductive tracks and the ground layer, or a break in a conductive track.

[0047] Similarly, each of the conductive layers CL2, CL3 in each of the pillars may comprise nested conductive tracks forming lattices which are connected to each other by vias such as V12, V23 and V34 to connect each of the two ends of the conductive tracks of the lattices of the layers CL4 and CL5 to a range of respective CP connection formed in the CL1 layer of the pillars SI, S2. In this way, it may also be possible for the DTC detection circuit to detect any attempt to pierce the pillars. The two ends of one of the conductive tracks PI, P2 in the mesh layers CL4, CL5 can be connected respectively to two connection pads of only one of the pillars or of both pillars respectively.

[0048] The vias in each of the pillars S1, S2 may be arranged sufficiently tightly against each other so as to prevent a drilling of one of the pillars from reaching the IC component without contacting or cutting one of the vias or contacting a conductive layer CL1-CL3. The position of the vias may be different in each of the pillars S1, S2 and may for example be determined randomly.

[0049] The multilayer printed circuit board including vias, from which the protection device is formed, can be manufactured by a conventional multilayer printed circuit manufacturing technique.

[0050] It will be clear to those skilled in the art that the present invention is susceptible to various variant embodiments and various applications. In particular, the invention is not limited to a protection device having a bridge shape arranged to house and cover an electronic component. Indeed, other shapes can be provided since the protection device can be manufactured by machining a multilayer printed circuit board, in order to form a sufficient space to house the IC component. Thus, Figure 6 represents a protection device PM', according to another embodiment. The protection device PM' differs from the protection device PM, in that it comprises a third pillar S3 facing a third side of the IC component and partially closing one of the openings of the protection device. The other two pillars are facing two opposite sides of the component.The S3 pillar can be positioned to allow sufficient space to accommodate the IC component under the protective device, with the top plate UL' of the PM' protective device being extended from the side of the S3 pillar to cover it entirely. Thus, the S3 pillar prevents access to the IC component through any of the openings in the PM' protective device.

[0051] The two ends of one of the conductive tracks PI, P2 forming one of the lattices can be connected to two conductive pads CP formed on the same pillar or on the two pillars respectively. Similarly, the ground layer CL6 can be connected to two conductive pads CP formed on the same pillar or on the two pillars respectively.

[0052] The connection pads CP can be replaced by pins to be plugged and soldered into holes formed in the printed circuit board BD.

Claims

Claims

1. 1. A protection device for protecting an electronic component (IC) implanted on a printed circuit board (BD) against an attack, the protection device (PM, PM') comprising: a multilayer printed circuit board comprising upper layers (CL4-CL6, IL4, IL5) and lower layers (CL1-CL3, IL1-IL3), the lower layers being machined to form two pillars (SI, S2) of a bridge, the pillars delimiting between them and with a lower face (LF) of the upper layers a volume configured to house the component to be protected, the pillars having a height such that the lower face delimits an empty space with an upper face of the component to be protected when the component to be protected and the protection device arranged above the component to be protected are fixed on the printed circuit board (BD), and conductive tracks (PI,P2) formed in the upper and lower layers and connecting together connection elements (CP) of the protection device formed in a lower conductive layer (CL1) of each of the pillars.,

2. 2. Protective device according to claim 1, wherein the lower layers (CL1-CL3, IL1-IL3) form a third pillar (S3) partially closing an opening of the bridge.

3. 3. A protection device according to claim 1 or 2, wherein the upper layers (CL4-CL6, IL4, IL5) comprise a first lattice layer (CL4, CL5) comprising at least two separate conductive tracks (PI, P2), nested one inside the other and together covering at least 80% of the upper surface of the upper layers, each conductive track comprising two ends connected respectively to two of the connection elements (CP) in the lower conductive layer (CL1) of the pillars (SI, S2, S3).

4. 4. A protection device according to claim 3, wherein the upper layers (CL4-CL6, IL4, IL5) comprise a second lattice layer (CL4, CL5) comprising at least two separate conductive tracks (PI, P2), nested one inside the other and arranged so that the spaces between the two conductive tracks (PI, P2) are located opposite one of the tracks formed on the first lattice layer (CL4, CL5), each conductive track comprising two ends connected respectively to two of the elements connection (CP) in the lower conductive layer of the pillars (SI, S2, S3).

5. 5. Protective device according to one of claims 1 to 4, wherein the upper layers (CL4-CL6, IL4, IL5) comprise a fully conductive ground layer (CL6), separated from the mesh layer (CL5) by an insulating layer (IL5), and connected to connection elements (CP) in the lower conductive layer (CL1) of the pillars (SI, S2, S3).

6. 6. A protection device according to claim 5, wherein the ground layer (CL6) is connected to a connection element (CP) in the lower conductive layer (CL1) of the pillars (S1, S2, S3) by a via (V16) passing through all the other layers located between the ground layer and the lower conductive layer of the pillars.

7. 7. Protection device according to one of claims 1 to 6, in which the lower layers (CL1-CL3, IL1-IL3) comprise several intermediate conductive layers (CL2, CL3) separated from each other, from the lower conductive layer (CL1) and from the upper layers, by insulating layers (IL1-IL3), the intermediate conductive layers comprising conductive tracks connected to each other, with conductive tracks of the upper layers (CL4-CL6, IL4, IL5) and with the connection elements (CP) of the lower layer (CL1), by vias (V12, V23, V34, V45).

8. 8. A method of manufacturing a protection device (PM, PM') for protecting an electronic component (IC) against an attack, the manufacturing method comprising steps of: manufacturing a multilayer printed circuit board comprising upper layers (CL4-CL6, IL4, IL5) and lower layers (CL1-CL3, IL1-IL3), connection elements (CP) formed in lateral portions (SI, S2) of a lower conductive layer (CL1), and conductive tracks (PI, P2) formed in the upper layers and in lateral portions of the lower layers and connecting the connection elements together, machining the lower layers to form two pillars of a bridge with the lateral portions (SI, S2) of the lower layers, so as to create an empty volume delimited by the pillars and a lower face (LF) of the upper layers, the empty volume having a determined extent to accommodate the component to be protected,the pillars having a height determined so that the lower face of the su- layers, upper delimits an empty space with an upper face of the component to be protected, when the component to be protected and the protection device arranged above the component to be protected are fixed on a printed circuit board (BD).

9. 9. Manufacturing method according to claim 8, in which the protection device (PM, PM') is in accordance with one of claims 1 to 7.

10. 10. Method for protecting an electronic component installed on a printed circuit board (BD), the method comprising steps consisting of: obtaining a protection device (PM, PM') according to one of claims 1 to 7, the protection device being configured to cover the component (IC) to be protected while leaving an empty space between an upper face of the component to be protected and a lower face of the protection device when the protection device is arranged above the component to be protected;and fixing the protection device on the printed circuit board, covering the component to be protected, the connection elements (CP) of the protection device being connected to a detection circuit (DTC) installed on the printed circuit board, the detection circuit being configured to detect a break in one of the conductive tracks (PI, P2) formed in the protection device or a short circuit between two of the conductive tracks formed in the protection device.;

11. 11. Protection method according to claim 10, wherein the protection device (PM, PM') is fixed on the printed circuit board (BD) in the same way as the component (IC) to be protected, by soldering connection pads (CP) of the protection device.

12. 12. Protection method according to claim 11, wherein the protection device (PM, PM') is fixed on the printed circuit board (BD) at the same time as the component (IC) to be protected.

13. 13. Payment terminal comprising a sensitive electronic component installed on a printed circuit board (BD), and a protection device (PM, PM') according to one of claims 1 to 7, the protection device being fixed on the printed circuit board so as to cover a component (IC) to be protected and connected to a detection circuit (DTC) formed on or in the printed circuit board and configured to detect a short circuit or a break in one of the conductive tracks (PI, P2) in the protection device.

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