Device for protecting the pins of an electronic component

The invention relates to a protective device for an electronic component including at least one pin to be electrically connected to an electronic system. The device includes at least one flexible printed circuit including first and second opposite surfaces, a central portion including a through opening for receiving the pin, and flaps connected to the central portion. The printed circuit is made of two insulation layers and includes at least one first conducting track between the two insulating layers, connecting the pin to the electronic system, a second conducting track extending on the first surface, and a third conducting track extending on the second surface. The flaps are folded back at least partially onto each other in order to encapsulate the pin and to electrically connect the second and third conducting tracks.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device for protecting the pins of an electronic component, for example, a magnetic read head.

2. Discussion of the Related Art

A check reader or a magnetic card reader generally comprises a magnetic read head connected to a printed circuit, which is generally called the reader motherboard. The magnetic read head is comprised of a rigid body containing the internal components of the head and access terminals. The access terminals correspond to metal pins which project from the body of the read head and enable transmission of the signals measured by the read head. The connections between pins of the read head and the motherboard may be wire connections.

Generally, the motherboard and the read head are arranged in a package in which protection devices are provided for detecting an unauthorized access to the motherboard. An example of a protection device corresponds to a flexible membrane at least partly covering the motherboard and in which a lattice-shaped conductive track is provided. The ends of the conductive track are connected to a protection circuit provided at the motherboard level. An attempt of access to the motherboard generally causes an interruption in the conductive track of the membrane. This is detected by the protection circuit and results, for example, in the stopping of the reader operation.

However, especially due to the position of the read head with respect to the motherboard in the reader package, it is generally not possible to protect the read head by means of conventional motherboard protection devices. An individual could then have access to the pins of the read head and collect the signals transmitted on these pins without for such an operation to be detected by the conventional protection devices of the reader.

To protect the pins of the read head, it is necessary to provide a dedicated protection device. A possibility is to partly encapsulate the read head in a rigid cap having an associated protection device, for example, of lattice membrane type. However, there exist many different types of readers, and thus many different arrangements of the read head and of the motherboard in the reader package. The cap shape must then be adapted case by case according to the positions of the read head and of the motherboard in the package. The cost of a protection device with a cap is thus high.

SUMMARY OF THE INVENTION

The present invention aims at a device for protecting the pins of an electronic component, for example a magnetic read head, to be connected to an electronic system, for example, a printed circuit, which authorizes some freedom on positioning of the electronic component with respect to the electronic system and which is likely to be formed at a low cost.

Thus, the present invention provides a device for protecting an electronic component comprising at least one pin to be electrically connected to an electronic system. The device comprises at least one flexible printed circuit comprising first and second opposite surfaces, a central portion comprising a through opening into which the pin is to be inserted, and flaps connected to the central portion. The flexible printed circuit is at least partly formed of the stack of two insulating layers and comprises at least a first conductive track between the two insulating layers, for electrically connecting the pin to the electronic system, a second conductive track extending on the first surface, and a third conductive track extending on the second surface. The flaps are capable of being at least partly folded back on one another to encapsulate the pin and electrically connect the second and third conductive tracks, whereby the second and third conductive tracks form a protection track to be electrically connected to the electronic system.

According to an embodiment, the device comprises a spacer capable of being arranged between the central portion and the flaps.

According to an embodiment, the spacer comprises an additional opening into which the pin is to be inserted.

According to an embodiment, the spacer comprises a threaded opening, the device comprising a screw having a threaded rod capable of cooperating with the threaded opening and a head capable of applying said flaps against the spacer.

According to an embodiment, the second and third conductive tracks are made of carbon.

According to an embodiment, the third conductive track comprises a widened conductive portion at the level of a first flap from among said flaps, the widened conductive portion being capable of being glued to the first surface of a second flap from among said flaps.

According to an embodiment, the second conductive track comprises a first conductive land at the level of a first flap from among said flaps and the third conductive track comprises a second conductive land at the level of a second flap from among said flaps, the first and second flaps being capable of being folded back against each other to put the first conductive land in electric contact with the second conductive land.

The present invention also provides a method for protecting an electronic component comprising at least one pin to be electrically connected to an electronic system. The method comprises the steps of providing a protection device comprising at least one flexible printed circuit comprising first and second opposite surfaces, a central portion comprising a through opening, and flaps connected to the central portion, the flexible printed circuit being at least partly formed of the stack of two layers and comprising at least a first conductive track between the two layers, a second conductive track extending on the first surface, and a third conductive track extending on the second surface, of inserting the pin into the opening, of connecting the first conductive track to the pin, and of at least partly folding back the flaps against one another to encapsulate the pin and electrically connect the second and third conductive tracks, whereby the second and third conductive tracks form a protection track to be electrically connected to the electronic system.

According to an embodiment, the method further comprises the steps of arranging a spacer against the central portion and of at least partly folding back the flaps against the spacer.

According to an embodiment, the third conductive track comprises a widened conductive portion at the level of a first flap from among said flaps. The method further comprises the step of gluing the widened conductive portion to the first surface of a second flap from among said flaps.

DETAILED DESCRIPTION

For clarity, the same elements have been designated with the same reference numerals in the different drawings.

An embodiment of a protection device will now be described for the protection of the pins of a magnetic read head connected to a motherboard of a reader, especially a check or magnetic card reader. However, the present invention may apply to the protection of the pins of any electronic component which must be connected to an electronic system while allowing, to a certain extent, a relative displacement between the electronic component and the electronic system.

The concept of the present invention is to connect the magnetic read head to the motherboard of the reader via a flexible printed circuit which, in addition to electrically connecting the read head pins to connection pads of the motherboard, protects the read head pins against an unauthorized access. This then provides the advantage of the low manufacturing cost of a flexible printed circuit. Further, the flexible printed circuit can at least partly deform. A same flexible printed circuit can thus be used while the magnetic read head and the motherboard are at different relative positions.

FIGS. 1 and 2are exploded front and back perspective views of a magnetic read head10and of the elements of an embodiment of a protection device20. Read head10comprises, in the present example, three slots12at its front surface and pins14at its rear surface. Each pin14for example corresponds to a metal rod which is a few millimeters high. Protection device20comprises a flexible printed circuit22and a spacer24. As an example, flexible printed circuit22is formed of a flexible membrane with a thickness on the order of 0.1 mm, for example, made of kapton (Dupont de Nemours trade mark), on a surface of which are distributed conductive tracks, called internal conductive tracks in the following description, for example, made of copper. The flexible printed circuit is covered with an insulating varnish on the side of the internal conductive tracks. Other conductive tracks, called external conductive tracks in the following description, for example made of a carbon or of silver ink, are distributed on the varnish layer and on the membrane surface opposite to the internal conductive tracks.

In the present example, flexible printed circuit22comprises a substantially rectangular central portion26. An upper flap28is connected to the upper edge of central portion26by a first connector portion30. A first lateral flap32is connected to a lateral edge of central portion26by a connector portion34. A second lateral flap36is connected to the opposite lateral edge of central portion26by a connector portion38and a lower flap40is connected to the lower edge of central portion26by a connector portion42. Lower flap40extends in a connection portion44comprising at its end a connection area45to be connected to the reader motherboard. As an example, each flap28,32,36,40, and each connection portion30,34,38,42is substantially rectangular. Call front surface46of flexible printed circuit22the surface visible inFIG. 1and rear surface47of flexible printed circuit22the surface visible inFIG. 2. As an example, the insulating varnish layer covering the membrane forming flexible printed circuit22is arranged on the side of rear surface47so that the external conductive tracks provided on the side of rear surface47can be connected to internal conductive tracks by simple openings provided in the varnish layer.

Central portion26is crossed by seven circular openings48distributed similarly to pins14of read head10. Conductive rings50surround each opening48on rear surface47of central portion26. Each conductive ring50is connected to one of the internal conductive tracks of flexible printed circuit22which connects conductive ring50to connection area45, the internal conductive tracks being shown only at the level of connection portion44and of connection portion45.

Upper flap28is crossed by a central opening53and two openings54distributed on either side of central opening53. Lower flap40is crossed by a central opening55and two openings56distributed on either side of central opening55. Lateral flap36is crossed by a central opening57and two openings58distributed on either side of central opening57. Lateral flap32is crossed by a central opening60.

Internal conductive tracks, for example, made of copper, and external conductive tracks (which may also be called lands or widened portions hereafter), for example made of carbon or silver ink, are dedicated to the protection of the pins of read head10. More specifically, as shown inFIG. 1, flexible printed circuit22comprises, at front surface46, an external conductive track62which snakes around openings48of central portion26and which connects two external conductive lands64,65, provided at the level of upper flap28. As shown inFIG. 2, at rear surface47, circuit22comprises an internal conductive track68which is connected to an external conductive land70provided at the level of lower flap40and which extends all the way to connection area45. At rear surface47, circuit22further comprises an internal conductive track72which is connected to an external conductive land74provided at the level of lower flap40and which extends all the way to connection area45. Internal conductive track72snakes at the level of lateral flaps32and36, of central portion26, of connector portions34,38,42, and of lower flap40. Two external widened conductive tracks76,78are provided on the path of conductive track72to which they are connected, a first external widened conductive track76at the level of lateral flap32and a second external widened conductive track78at the level of lateral flap36. The arrangement of internal conductive tracks68,72and of external conductive track62inFIGS. 1 and 2is disclosed as an example only and may be different from what is shown.

Spacer24has a general parallelepipedal shape, with its largest surface having substantially the same dimensions as central portion26. Spacer24is crossed by seven openings80substantially distributed in the same way as pins14of read head10. It also comprises, on one surface, two protrusions81and two outward-projecting pads82. Finally, it comprises an opening84, which may be threaded.

FIGS. 3A to 3Fare rear perspective views illustrating successive steps of an example of a method for assembling protection device20on read head10. In the drawings, only external conductive lands64,65,70,74, and external widened conductive portions76,78have been shown.

FIG. 3Ashows protection device20after having carried out the steps of: gluing read head10on front surface46of central portion26of flexible printed circuit22while inserting pins14of read head10into openings48of central portion26; welding pins14to conductive rings50on the side of rear surface47of flexible printed circuit22; and arranging spacer24against central portion26on the side of rear surface47of flexible printed circuit22by insertion of pins14into openings80of spacer24, with pads82being arranged on the side opposite to central portion26. Preferably, the thickness of spacer24is selected so that pins14do not protrude from spacer24.

FIG. 3Bshows protection device20once upper flap28has been folded back against spacer24. Connection portion30between central portion26and upper flap28takes a curved shape to enable the folding of upper flap28. The thickness of spacer24, for example of a few millimeters, ensures for the radius of curvature of connection portion30not to be too small. Openings54of upper flap28are arranged so that, after folding back of upper flap28, pads82of spacer24penetrate into said openings, which ensures an appropriate positioning of upper flap28on spacer24. Central opening53of upper flap28is located, after folding back, in prolongation of opening84of spacer24. Protrusions81are arranged on spacer24to be located, after folding back of upper flap28, at the level of conductive lands64,65.

FIG. 3Cshows protection device20after having folded back lower flap40against upper flap28. Connector portion42between lower flap40and central portion26takes a curved shape to enable the folding back of lower flap40. Openings56of lower flap40are arranged so that, after folding back of lower flap40, pads82of spacer24penetrate into said openings, which ensures an appropriate positioning of lower flap40on upper flap28. Central opening55of lower flap40is located, after folding back, in prolongation of opening84of spacer24. After folding back of lower flap40, external conductive land70of lower flap40bears against external conductive land65of upper flap28and eternal conductive land74of lower flap40bears against external conductive land64of upper flap28. Conductive glue may be previously applied on external conductive lands64,65,70,74to improve the electric connection between them. External conductive track62is then electrically connected to internal conductive track68by the connection of lands65and70and is electrically connected to internal conductive track72by the connection of lands64and74. Protrusions81provide a good contact between lands64and70on the one hand and lands65and74on the other hand on folding back of lower flap40. Conductive tracks68,62, and72are thus series-connected so that a continuous protection track running across flexible printed circuit22and connected, at its ends, to connection area45, is obtained.

FIG. 3Dshows protection device20after having folded back lateral flap36against lower flap40. Connector portion38is at least partly folded to enable folding back of lateral flap36. Openings58of lateral flap36are arranged so that, after folding back of lateral flap36, pads82of spacer24penetrate into said openings, which provides an appropriate positioning of lateral flap36on lower flap40. Central opening57of lateral flap36is located, after folding back, in prolongation of opening84of spacer24. Before folding back of lateral flap36, glue is applied at the level of widened external conductive portion78, thus ensuring the fastening of lateral flap36to lower flap40after folding back.

FIG. 3Eshows the structure obtained after having folded back lateral flap32on lateral flap36. Connector portion34is a least partly folded to enable a folding back of lateral flap32. Central opening60of lateral flap32is located, after folding back, in prolongation of opening84of spacer24. Before folding back of lateral flap32, glue is applied at the level of external conductive portion76, thus ensuring the fastening of lateral flap32to lateral flap36after folding back. InFIG. 3E, a washer90and a screw91have also been shown. Screw91comprises a threaded stem92and a head93.

Flexible printed circuit22can then be connected to the reader motherboard at the level of connection area45of connection portion44. Connection portion44being flexible, it can be “deformed” to adapt to the relative position between read head10and the motherboard.

According to a variation of the previously-described embodiment, the cohesion of protection device20is only ensured by the gluing areas provided at the level of widened external conductive portions76,78. Screw92may then be omitted. According to another variation, the pressure provided by screw92is sufficient to ensure a convenient contact between lands64,65and lands70,74. It may then not be necessary to provide conductive glue connecting lands64,65to lands70,74.

When flexible printed circuit22is connected to the motherboard, external conductive tracks68,72and internal conductive track62form a continuous track which is connected to a protection circuit provided at the motherboard level. The protection circuit is capable of detecting an interruption in conductive tracks62,68,72, which may correspond to an attempt of unauthorized access to pins14of read head10. The protection circuit can then control the stopping of the reader and the deleting of all the critical data stored at the motherboard level. As an example, an interruption in conductive track62occurs by tearing during an attempt of retrieval of read head10from protection device20. According to another example, if someone removes screw92and attempts to open lateral flap32, this results in a tearing of widened conductive portion76and thus in a rupture of conductive track72. External widened conductive portions76and78are then used as fuses since they are respectively glued on flaps36and44and tear in case of an opening of the flaps. An interruption in conductive tracks62,68,72may also correspond to an attempt to damage, for example, by cutting, flexible printed circuit22.

In the previously-described embodiment, external conductive track62is connected to internal conductive tracks68,72via lands64,65,70and74. According to a variation, external conductive track62may be connected to tracks68,72by vias crossing the membrane of flexible printed circuit22. This enables to avoid for external conductive track62to extend on connection portion30where it is then directly accessible.

FIG. 4is a simplified cross-section view of a portion of flexible printed circuit22comprising a flexible membrane94, an internal conductive track96, for example made of copper, formed on membrane94, an insulating varnish layer98covering internal conductive track96, and an external conductive track100, for example made of carbon, arranged on the side of membrane94opposite to internal conductive track96. According to the previously-described variation, external conductive track100is connected to internal conductive track96by a via102crossing membrane94.

Specific embodiments of the present invention have been described. Various alterations and modifications will occur to those skilled in the art. In particular, the number and the shape of the flaps may be adapted to the shape of the read head.