Abstract:
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.

Description:
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. 
     The foregoing and other objects, features, and advantages of the present invention will be discussed in detail in the following non-limiting description of specific embodiments in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 and 2  are exploded front and back perspective views of the elements of an embodiment of a magnetic read head protection device; 
         FIGS. 3A to 3F  illustrate successive steps of an example of a method for assembling the protection device of  FIGS. 1 and 2  to a magnetic read head; and 
         FIG. 4  is a partial simplified view of a variation of the protection device. 
     
    
    
     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 2  are exploded front and back perspective views of a magnetic read head  10  and of the elements of an embodiment of a protection device  20 . Read head  10  comprises, in the present example, three slots  12  at its front surface and pins  14  at its rear surface. Each pin  14  for example corresponds to a metal rod which is a few millimeters high. Protection device  20  comprises a flexible printed circuit  22  and a spacer  24 . As an example, flexible printed circuit  22  is 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 circuit  22  comprises a substantially rectangular central portion  26 . An upper flap  28  is connected to the upper edge of central portion  26  by a first connector portion  30 . A first lateral flap  32  is connected to a lateral edge of central portion  26  by a connector portion  34 . A second lateral flap  36  is connected to the opposite lateral edge of central portion  26  by a connector portion  38  and a lower flap  40  is connected to the lower edge of central portion  26  by a connector portion  42 . Lower flap  40  extends in a connection portion  44  comprising at its end a connection area  45  to be connected to the reader motherboard. As an example, each flap  28 ,  32 ,  36 ,  40 , and each connection portion  30 ,  34 ,  38 ,  42  is substantially rectangular. Call front surface  46  of flexible printed circuit  22  the surface visible in  FIG. 1  and rear surface  47  of flexible printed circuit  22  the surface visible in  FIG. 2 . As an example, the insulating varnish layer covering the membrane forming flexible printed circuit  22  is arranged on the side of rear surface  47  so that the external conductive tracks provided on the side of rear surface  47  can be connected to internal conductive tracks by simple openings provided in the varnish layer. 
     Central portion  26  is crossed by seven circular openings  48  distributed similarly to pins  14  of read head  10 . Conductive rings  50  surround each opening  48  on rear surface  47  of central portion  26 . Each conductive ring  50  is connected to one of the internal conductive tracks of flexible printed circuit  22  which connects conductive ring  50  to connection area  45 , the internal conductive tracks being shown only at the level of connection portion  44  and of connection portion  45 . 
     Upper flap  28  is crossed by a central opening  53  and two openings  54  distributed on either side of central opening  53 . Lower flap  40  is crossed by a central opening  55  and two openings  56  distributed on either side of central opening  55 . Lateral flap  36  is crossed by a central opening  57  and two openings  58  distributed on either side of central opening  57 . Lateral flap  32  is crossed by a central opening  60 . 
     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 head  10 . More specifically, as shown in  FIG. 1 , flexible printed circuit  22  comprises, at front surface  46 , an external conductive track  62  which snakes around openings  48  of central portion  26  and which connects two external conductive lands  64 ,  65 , provided at the level of upper flap  28 . As shown in  FIG. 2 , at rear surface  47 , circuit  22  comprises an internal conductive track  68  which is connected to an external conductive land  70  provided at the level of lower flap  40  and which extends all the way to connection area  45 . At rear surface  47 , circuit  22  further comprises an internal conductive track  72  which is connected to an external conductive land  74  provided at the level of lower flap  40  and which extends all the way to connection area  45 . Internal conductive track  72  snakes at the level of lateral flaps  32  and  36 , of central portion  26 , of connector portions  34 ,  38 ,  42 , and of lower flap  40 . Two external widened conductive tracks  76 ,  78  are provided on the path of conductive track  72  to which they are connected, a first external widened conductive track  76  at the level of lateral flap  32  and a second external widened conductive track  78  at the level of lateral flap  36 . The arrangement of internal conductive tracks  68 ,  72  and of external conductive track  62  in  FIGS. 1 and 2  is disclosed as an example only and may be different from what is shown. 
     Spacer  24  has a general parallelepipedal shape, with its largest surface having substantially the same dimensions as central portion  26 . Spacer  24  is crossed by seven openings  80  substantially distributed in the same way as pins  14  of read head  10 . It also comprises, on one surface, two protrusions  81  and two outward-projecting pads  82 . Finally, it comprises an opening  84 , which may be threaded. 
       FIGS. 3A to 3F  are rear perspective views illustrating successive steps of an example of a method for assembling protection device  20  on read head  10 . In the drawings, only external conductive lands  64 ,  65 ,  70 ,  74 , and external widened conductive portions  76 ,  78  have been shown. 
       FIG. 3A  shows protection device  20  after having carried out the steps of: gluing read head  10  on front surface  46  of central portion  26  of flexible printed circuit  22  while inserting pins  14  of read head  10  into openings  48  of central portion  26 ; welding pins  14  to conductive rings  50  on the side of rear surface  47  of flexible printed circuit  22 ; and arranging spacer  24  against central portion  26  on the side of rear surface  47  of flexible printed circuit  22  by insertion of pins  14  into openings  80  of spacer  24 , with pads  82  being arranged on the side opposite to central portion  26 . Preferably, the thickness of spacer  24  is selected so that pins  14  do not protrude from spacer  24 . 
       FIG. 3B  shows protection device  20  once upper flap  28  has been folded back against spacer  24 . Connection portion  30  between central portion  26  and upper flap  28  takes a curved shape to enable the folding of upper flap  28 . The thickness of spacer  24 , for example of a few millimeters, ensures for the radius of curvature of connection portion  30  not to be too small. Openings  54  of upper flap  28  are arranged so that, after folding back of upper flap  28 , pads  82  of spacer  24  penetrate into said openings, which ensures an appropriate positioning of upper flap  28  on spacer  24 . Central opening  53  of upper flap  28  is located, after folding back, in prolongation of opening  84  of spacer  24 . Protrusions  81  are arranged on spacer  24  to be located, after folding back of upper flap  28 , at the level of conductive lands  64 ,  65 . 
       FIG. 3C  shows protection device  20  after having folded back lower flap  40  against upper flap  28 . Connector portion  42  between lower flap  40  and central portion  26  takes a curved shape to enable the folding back of lower flap  40 . Openings  56  of lower flap  40  are arranged so that, after folding back of lower flap  40 , pads  82  of spacer  24  penetrate into said openings, which ensures an appropriate positioning of lower flap  40  on upper flap  28 . Central opening  55  of lower flap  40  is located, after folding back, in prolongation of opening  84  of spacer  24 . After folding back of lower flap  40 , external conductive land  70  of lower flap  40  bears against external conductive land  65  of upper flap  28  and eternal conductive land  74  of lower flap  40  bears against external conductive land  64  of upper flap  28 . Conductive glue may be previously applied on external conductive lands  64 ,  65 ,  70 ,  74  to improve the electric connection between them. External conductive track  62  is then electrically connected to internal conductive track  68  by the connection of lands  65  and  70  and is electrically connected to internal conductive track  72  by the connection of lands  64  and  74 . Protrusions  81  provide a good contact between lands  64  and  70  on the one hand and lands  65  and  74  on the other hand on folding back of lower flap  40 . Conductive tracks  68 ,  62 , and  72  are thus series-connected so that a continuous protection track running across flexible printed circuit  22  and connected, at its ends, to connection area  45 , is obtained. 
       FIG. 3D  shows protection device  20  after having folded back lateral flap  36  against lower flap  40 . Connector portion  38  is at least partly folded to enable folding back of lateral flap  36 . Openings  58  of lateral flap  36  are arranged so that, after folding back of lateral flap  36 , pads  82  of spacer  24  penetrate into said openings, which provides an appropriate positioning of lateral flap  36  on lower flap  40 . Central opening  57  of lateral flap  36  is located, after folding back, in prolongation of opening  84  of spacer  24 . Before folding back of lateral flap  36 , glue is applied at the level of widened external conductive portion  78 , thus ensuring the fastening of lateral flap  36  to lower flap  40  after folding back. 
       FIG. 3E  shows the structure obtained after having folded back lateral flap  32  on lateral flap  36 . Connector portion  34  is a least partly folded to enable a folding back of lateral flap  32 . Central opening  60  of lateral flap  32  is located, after folding back, in prolongation of opening  84  of spacer  24 . Before folding back of lateral flap  32 , glue is applied at the level of external conductive portion  76 , thus ensuring the fastening of lateral flap  32  to lateral flap  36  after folding back. In  FIG. 3E , a washer  90  and a screw  91  have also been shown. Screw  91  comprises a threaded stem  92  and a head  93 . 
       FIG. 3F  shows the structure obtained after having screwed rod  92  of screw  91  into threaded opening  84  of spacer  24 , washer  90  being interposed between lateral flap  32  and head  93  of screw  91 . Head  93  of screw  91  then presses flaps  28 ,  32 ,  36 ,  40  against spacer  24 . 
     Flexible printed circuit  22  can then be connected to the reader motherboard at the level of connection area  45  of connection portion  44 . Connection portion  44  being flexible, it can be “deformed” to adapt to the relative position between read head  10  and the motherboard. 
     According to a variation of the previously-described embodiment, the cohesion of protection device  20  is only ensured by the gluing areas provided at the level of widened external conductive portions  76 ,  78 . Screw  92  may then be omitted. According to another variation, the pressure provided by screw  92  is sufficient to ensure a convenient contact between lands  64 ,  65  and lands  70 ,  74 . It may then not be necessary to provide conductive glue connecting lands  64 ,  65  to lands  70 ,  74 . 
     When flexible printed circuit  22  is connected to the motherboard, external conductive tracks  68 ,  72  and internal conductive track  62  form 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 tracks  62 ,  68 ,  72 , which may correspond to an attempt of unauthorized access to pins  14  of read head  10 . 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 track  62  occurs by tearing during an attempt of retrieval of read head  10  from protection device  20 . According to another example, if someone removes screw  92  and attempts to open lateral flap  32 , this results in a tearing of widened conductive portion  76  and thus in a rupture of conductive track  72 . External widened conductive portions  76  and  78  are then used as fuses since they are respectively glued on flaps  36  and  44  and tear in case of an opening of the flaps. An interruption in conductive tracks  62 ,  68 ,  72  may also correspond to an attempt to damage, for example, by cutting, flexible printed circuit  22 . 
     In the previously-described embodiment, external conductive track  62  is connected to internal conductive tracks  68 ,  72  via lands  64 ,  65 ,  70  and  74 . According to a variation, external conductive track  62  may be connected to tracks  68 ,  72  by vias crossing the membrane of flexible printed circuit  22 . This enables to avoid for external conductive track  62  to extend on connection portion  30  where it is then directly accessible. 
       FIG. 4  is a simplified cross-section view of a portion of flexible printed circuit  22  comprising a flexible membrane  94 , an internal conductive track  96 , for example made of copper, formed on membrane  94 , an insulating varnish layer  98  covering internal conductive track  96 , and an external conductive track  100 , for example made of carbon, arranged on the side of membrane  94  opposite to internal conductive track  96 . According to the previously-described variation, external conductive track  100  is connected to internal conductive track  96  by a via  102  crossing membrane  94 . 
     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. 
     Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and the scope of the present invention. Accordingly, the foregoing description is by way of example only and is not intended to be limiting. The present invention is limited only as defined in the following claims and the equivalents thereto.