DE102015103489A1 - Method for producing an electrically conductive connection in a chip card - Google Patents

Abstract

The invention relates to a method for producing an electrically conductive connection between a first electrical component (102) of a chip card (100) and a second electrical component (204), wherein the first electrical component (102) has a first contact surface (104) the second electrical component (204) has a second contact surface (106). The method initially comprises applying a pasty, electrically conductive polyurethane material (112) to the first contact surface (104). Subsequently, the electrically conductive polyurethane material (112) is cured, whereupon the second contact surface (106) is pressed onto the cured, electrically conductive polyurethane body (112). Subsequently, the second electrical component (204) is attached to the chip card (100) and / or the first electrical component (102).

Description

The invention relates to a method for producing an electrically conductive connection in a chip card and a chip card.

Typically, smart cards are manufactured by introducing electrical components, for example chip modules, into a smart card body. A typical chip card may, in addition to a first electrical component such as a chip module also have other electrical components, such as interfaces such as an antenna or energy sources such as a battery. As a rule, an electrically conductive connection between contacts of the said first electrical component and the contacts of one or more further electrical components is required for the functional capability of a chip card constructed in this way.

The technical requirements of the described electrically conductive connection are especially in smart cards, for which a long life is provided, considerable. When using the chip card, on the one hand, mechanical stresses occur, since strong mechanical stresses can be induced due to bending, torsion and different thermal expansion coefficients of the materials used. On the other hand, media, moisture and condensation during thermal cycling lead to a corrosive load on the connection.

The invention has for its object to provide an improved smart card and an improved method for producing a smart card.

The object underlying the invention is solved by the features of the independent claims. Preferred embodiments of the invention are indicated in the dependent claims.

The invention relates to a method for producing an electrically conductive connection between a first electrical component such as an antenna and a second electrical component such as a chip module. In this case, the first electrical component has a first contact surface and the second electrical component has a second contact surface. The method comprises first applying a pasty, electrically conductive polyurethane material on the first contact surface, which has the property to solidify by temperature change or chemical reaction such as polymerization. Subsequently, the electrically conductive polyurethane material is solidified, whereby it enters into a adhesive bond with the first contact surface. In a further step of the method, the second contact surface is pressed onto the solidified, electrically conductive polyurethane body and the component with the second contact surface is fastened to the chip card and / or the first electrical component.

Embodiments of the invention may have the advantage that the electrically conductive connection between the first electrical component such as an antenna and a second electrical component such as a chip module produced by the method described above due to the elastic properties of the polyurethane material even under mechanical loads of the chip card ensures a long service life of contacting the electrical elements of the chip card. By pressing the second contact surface on the solidified polyurethane material and the simultaneous fixing of the second electrical component or module to the chip card and / or the first electrical component is formed within the polyurethane material, a mechanical stress. This mechanical tension ensures a permanent connection between the second contact surface and the electrically conductive polyurethane material, since the electrically conductive polyurethane material is permanently pressed against the second contact surface. At the same time, the conductive polyurethane body is adhesively bonded to the first contact surface. Thus, a permanent, electrically conductive connection between the first and second electrical component can be ensured.

In this case, the method described can be used both for producing a chip card having at least two components and for producing a semifinished product having at least two components.

Since the polyurethane material does not adhere to the second contact surface, but is merely pressed, a contact loss due to a tear of an adhesive bond between the polyurethane material and the second contact surface can be avoided under mechanical stress such as torsion and the shear stresses occurring. The polyurethane material can namely move along the second contact surface, but due to the mechanical stress within the polyurethane body, it is always ensured that the electrical contact between the contact surface of the first electrical component and the contact surface of one or more further electrical components is maintained , This can be ensured over the entire life of the chip card that the mechanical and electrical properties of the electrically conductive connection and thus important properties of the chip card or semifinished product remain unchanged.

In particular, the use of polyurethane may have the advantage that polyurethane is characterized by a high dimensional stability and a good aging resistance. Thus, in particular, the use of a pasty, electrically conductive polyurethane material with the ability to solidify favors the durability of the compound.

The first electrical component may be, for example, an antenna or a battery, while the second electrical component may be, for example, a chip module such as a sensor module. The chip card can be, for example, a dual-interface chip card (DIC), ie a chip card with a contact-type and a contactless data transmission interface, both of which are controlled by the same chip module. Usually, in these chip cards, the chip module for producing the contactless function is electrically conductively connected to, for example, an RFID antenna embedded in the chip card body.

According to one embodiment, the electrically conductive polyurethane material has a pasty mixture of a polyurethane-based adhesive and metallic particles. In the context of the present invention, a pasty material is understood as meaning a material which has a viscosity of more than 10 ⁶ mPa s at room temperature.

Embodiments of the invention may have the advantage that due to the statistical distribution of the metallic particles in the matrix of the polyurethane-based adhesive upon compression of the solidified polyurethane body, the average spacing between the metallic particles within the adhesive decreases. As a result, when the adhesive is compressed, the conductivity of the polyurethane material applied to the first contact surface in the course of the described method increases at the same time. This effect would not occur when using a polyurethane adhesive for double-sided adhesive bonding of the first and second contact surface, since this would eliminate a compression of the polyurethane-based adhesive after solidification of the adhesive and the associated reduction in the mean distance of the metallic particles ,

According to a further embodiment, the metallic particles are silver particles, which are distinguished in particular by a high conductivity and good corrosion resistance.

According to a further embodiment, the crosslinking of the electrically conductive polyurethane material is at least 90% complete by the solidification of the pasty, electrically conductive polyurethane material. By "crosslinking" is meant a chemical process by which a plurality of individual macromolecules of the polyurethane are linked to a three-dimensional network. In this way, sufficient rigidity of the polyurethane body applied to the first contact surface in the course of the method described can be ensured, while a high degree of elasticity can be achieved by the partial spatial cross-linking. Furthermore, it is envisaged that the polyurethane material in the course of solidification loses its adhesive properties as far as possible or even completely.

According to a further embodiment, the second electrical component is attached by an adhesive bond and / or a clamping connection and / or a latching connection to the chip card and / or the first electrical component. The selection of which of the aforementioned types of connection is to be used depends on the design conditions, for example the thickness of the chip card and the size of the applied second electrical component. Thus, for example, in the case of a very small component, an adhesive connection may be advantageous due to a small space requirement, while in the case of a large module or a thick chip card a locking connection or a clamping connection is preferable, which could provide higher holding forces. For this purpose, however, sufficient space for the arrangement of locking or clamping devices is necessary on the chip card body. When designing the connection used, care must be taken that the holding force of the connection is sufficient to compensate for the restoring force exerted by the compressed polyurethane body on the electrical component.

According to a further embodiment, attaching the second electrical component to the chip card and / or the first electrical component comprises first applying a thermally active adhesive to the second electrical component and / or the chip card and / or the first electrical component. Subsequently, the second electrical component is pressed onto the chip card and / or the first electrical component. At the same time, the thermally activatable adhesive is heated so that an adhesive bond is formed between the second electrical component or module and the chip card. Embodiments of the invention may have the advantage have that the method described above for connecting the second electrical component or module and the chip card and / or the electrical component can be easily implemented in an automated production of smart cards.

According to one embodiment, the pasty, electrically conductive polyurethane material is applied to the first contact surface by volumetric dispensing. Embodiments of the invention may have the advantage that by volumetric dispensing, a low cost application may be used.

According to a further embodiment, the chip card has a chip card body, wherein the first electrical component is embedded in the chip card body. The first contact surface is arranged within a recess of the chip card body. The amount of pasty, electrically conductive polyurethane material which has been dispensed onto the first contact surface in the course of the method described is then selected such that after hardening of the electrically conductive polyurethane material the hardened polyurethane body protrudes beyond the recess. In this way it can be ensured that when the second electrical component or module is pressed onto the chip card body, a contacting between the first contact area and the second contact area by the electrically conductive polyurethane material is possible. It should be noted that in the course of solidification of the polyurethane material by crosslinking the volume of the polyurethane material may decrease. Therefore, when determining the amount of polyurethane material to be dispensed, the corresponding volume decrease during solidification must be taken into account.

According to a further embodiment, the amount of pasty, electrically conductive polyurethane material applied to the first contact surface is selected so that after the solidification of the electrically conductive polyurethane material and the pressing on of the second contact surface on the solidified electrically conductive polyurethane body of the solidified electrically conductive polyurethane material is completely absorbed in the recess. If, for example, the recess of the chip card were completely filled with polyurethane material, wherein at the same time the solidified polyurethane material protrudes beyond the recess, the restoring force of the deformed polyurethane body would be so great when the second electrical component or module is pressed onto the polyurethane body in that damage to the electrical component would be feared. However, if previously the recess in the chip card body is not completely filled with polyurethane material, the unfilled space of the recess in the chip card body can be occupied by the deformed polyurethane body when the electrical component or module is pressed onto the polyurethane material. In this way, by a suitable design of the shape of the polyurethane body, the force acting on the electrical component or module force can be kept within acceptable limits, in which no damage to the electrical components is to be feared.

Further, by completely enclosing the polyurethane body in a recess of the chip card body, the electrically conductive polyurethane material could be protected against external influences, in particular weather influences. For example, moisture penetration can be avoided, thereby reducing the likelihood of corrosion at the interfaces of the electrically conductive particles within the polyurethane material.

According to a further embodiment, the paste-like, electrically conductive polyurethane material is applied to the first contact surface such that the solidification of the pasty, electrically conductive polyurethane material results in an elastic polyurethane body which protrudes from a base surface adhering to the first contact surface tapered away from the first contact surface. For example, the shape of the elastic polyurethane body may be a cone or a truncated cone.

Embodiments of the invention may have the advantage that, especially in the case of a conical shape, the base area can be selected to be very large, so that there is good contact of the polyurethane body with the first contact area, while at the same time the narrower tip of the conical polyurethane body after the compression by the compression of the second electrical component or module exerts only a small restoring force on the second electrical component or module. In this way it can be avoided that the second electrical component or module is damaged due to an excessive restoring force of the elastically deformed polyurethane body.

In a further aspect, the invention relates to a smart card which has been produced according to the method described above.

It should be noted that the above-described embodiments of the invention may be combined with each other in an arbitrary manner as long as the combined embodiments are not mutually exclusive.

In the following, preferred embodiments of the invention are explained in more detail with reference to the drawings.

Show it:

1 Cross-sectional views of a smart card, and

2 Various process steps for producing a smart card.

Hereinafter, similar elements will be denoted by the same reference numerals.

The 1 shows a schematic overview of manufacturing steps for producing a smart card according to the method described above. In 1a is first the card body 100 can be seen, in which already the first electrical component 102 with his electrical contact 104 , for example by application of a lamination process, is embedded. The card body 100 also has the recess 110 on.

In 1b became a pasty, electrically conductive polyurethane material 112 into the recess 110 introduced and on the electrical contact 104 applied. In the electrically conductive polyurethane material 112 For example, it is an adhesive in which polyurethane material is used as a matrix for metallic particles, for example silver particles.

Furthermore, in 1b a contact of a second electrical component can be seen, wherein the contact with the reference numeral 106 is marked. By moving in the direction 108 that is, a movement perpendicular to the surface of the card body 100 will be in the 1b the contact surface 106 on the electrically conductive material 112 applied.

It is in the in 1b shown situation of the electrically conductive polyurethane body 112 already extensively solidified by cross-linking or cooling, so that it has lost its adhesive properties. So it is now on the first contact surface 104 patch, elastically deformable, electrically conductive polyurethane body 112 , It has after the application of the electrically conductive polyurethane material 112 first a wetting of the contact surface 104 due to adhesion forces between the contact surface 104 and the electrically conductive polyurethane material 112 occurred. This results in a tapered polyurethane body emanating from a broad base 112 , On the contact surface 106 facing side has the polyurethane body 112 Furthermore, due to cohesive forces, an approximate hemispherical shape is assumed.

In the in 1c The situation described became the second contact surface 106 on the polyurethane body 112 along the direction 108 Pressed so that the elastic polyurethane body 112 especially at its contact surface 106 facing tip was elastically deformed. Further, the contact surface became 106 the second electrical (not shown here) component or module on the chip card body 100 for example, attached by an adhesive, clamping or latching connection, so that one of the deformed polyurethane body 112 on the first contact surface 106 applied restoring force of the attachment of the contact surface 106 or of the electrical component or module can be compensated.

As the electrically conductive polyurethane body 112 the recess 110 in the 1c does not completely fill, the material is capable of, in longitudinal direction of the recess, that is in 1c to the left and to the right toward the short edge of the card body 100 dodge. This allows the elastically deformed polyurethane body 112 on the contact surface 106 exercised restoring forces are kept low. This is especially due to the tapered shape of the polyurethane body 112 supported.

Would now in the 1c on the contact surface 106 by a mechanical action from the outside a force in the direction 108 This would cause a slight deformation of the contact 106 and optionally also the card body 100 cause. However, this has no influence on the electrical contact between the contact surface 106 and contact area 104 as the electrically conductive polyurethane body 112 due to its elastic properties of a corresponding deformation of the contact surface 106 or the card body 100 can adapt without physical contact with any of the contact surfaces 104 or 106 to lose. For example, the dome of the polyurethane body could 112 at a twist of the card body 100 along the contact surface 106 slide off without contact with the contact surface 106 to lose. The material 112 can thus escape the force and the mechanical deformation of the overall structure and, for example, in the 1c with its tip to the left and to the right at the contact surface 106 glide along.

Another advantage is that, if the contact surfaces 104 and 106 Remove from each other, also the electrical contact between these two contact surfaces is maintained. However, this assumes that the distance between the first contact surface 104 and the second contact area 106 never becomes larger than the height of the elastic polyurethane body 112 in its relaxed, undeformed state. If this is guaranteed, the polyurethane body can 112 an increase in the distance of the second contact surface 106 opposite the first contact surface 104 due to its elastic properties follow without contact with the second contact surface 106 to lose. So it raises z. B. the contact surface 106 a little bit contrary to the direction 108 from the card body 100 on, for example in a range of 50-100 microns, this could be due to the elastic and electrically conductive polyurethane body 112 be compensated.

Also in case of a strong heating of the card body 100 For example, if the smart card is left over a certain period of time on a warm surface such as a heater, the electrically conductive polyurethane material 112 with only slight mechanical influence of the contacts 104 and 106 experience a thermal expansion. For this purpose, the recess offers 110 enough space, so that of the polyurethane body 112 on the first contact surface 104 and the second contact surface 106 applied restoring force remains within acceptable limits, within which damage to the contact surfaces 104 . 106 or the chip card 100 can be avoided.

In all cases described the change in shape of the chip card body 100 due to thermal or mechanical loads is due to the one-sided adhesive adhesion of the contacts 106 and 104 through the elastic and electrically conductive polyurethane material 112 ensures that the electrical contact is maintained.

Thus it can be summarized that in the 1 a pasty, electrically conductive polyurethane material is used. This is first by a suitable application method such as volumetric dispensing on the deepened in the card body 100 lying contact surface 104 of the first electrical component embedded in the card body 102 , for example, an antenna applied. In a further process step then the polyurethane material 112 Hardened, giving an elastic, electrically conductive polyurethane body 112 receives. Subsequently, the second electrical component, for example a chip module, with its contact 106 in or on the chip card body. The contact surface 106 comes thereby with the elastic, electrically conductive polyurethane body 112 in contact and compresses this. Due to the restoring force of the elastically deformed polyurethane body 112 this is always at the contact surface 106 pressed, so that an electrically conductive connection between the contact surface 104 and the contact surface 106 consists. Finally, the contact surface 106 or the associated electrical component or module on the chip card body 100 attached.

The 2 shows a schematic overview of the various process steps that it takes to produce a smart card.

Shown is in 2 in each case a cross-sectional view through and a plan view of the card body 100 for each process step. The procedure begins in 2a with the provision of a card body 100 in which the contact surface 104 is embedded. For example, it is at the contact surface 104 around a part of an antenna. As can be seen, the contact surface 104 meander-shaped. This increases the likelihood of an efficient contact with the electrically conductive material - the meaning of this is later, in particular with regard to 2c and 2d better understandable.

In 2 B Initially, the creation of two different recesses. For one, this is the recess 202 which represents a recess for receiving the chip module to be introduced. In the embodiment of the 2 Thus, it is assumed without restriction of generality that the second electrical component to be contacted is a so-called chip module. The further deepening 200 serves primarily the purpose of providing an adhesive surface over which in a final process step ( 2f ) the chip module permanently with the card body 100 can be connected.

After creating the recesses 200 and 202 takes place in 2c generating the recess 110 , for example by milling. The milling process takes place in the area of the adhesive surface (recess 200 ) of the chip module to be applied and above the meandering contact area 104 instead of. In the supervision on the card body in 2c is through the recess 110 through the underlying meandering contact area visible.

In it can be seen that the electrically conductive polyurethane material 112 in a further process step in the recess 110 is introduced. Due to the meander-shaped contact 104 Now it is ensured that with a high probability at least a portion of the meander turns in electrical connection with the electrically conductive polyurethane material 112 occurs. Even with inaccurate milling of the recess 110 in the step of 2c So it would be ensured that an efficient contact between the contact 104 and the electrically conductive polyurethane material 112 can be achieved.

Finally done in 2e the introduction of the chip module, which in the following with reference numerals 204 is marked. In this case, the period of time which is between the method step of 2d and the method step of 2e passes, so chosen that the electrically conductive polyurethane adhesive 112 cured by crosslinking so far that it is from now on elastically deformable and has largely lost its adhesive properties. The chip module points next to an upper side 210 also contact surfaces 106 on. Between the contact surfaces 106 and 104 is about the electrically conductive polyurethane material 112 an electrical connection can be made. This is the chip module 204 in the direction 108 on the card body 100 placed. The contact surfaces 106 laterally surrounding adhesive surfaces 206 of the chip module 204 also serve the recess 110 To seal against moisture and media. For this comes the adhesive surface 206 with the adhesive surface 200 in touch. By an appropriate gluing process, as in 2f visible, then the electrically conductive polyurethane body 112 completely in the recess 110 locked in. To this surrounds the adhesive surface 206 completely the contact surface 106 as well as the recess 110 ,

The result is the chip card, as shown in 2f is apparent. The chip card has on its top further contact surfaces 210 of the chip module 204 on.

In summary, it should be noted that the electrically conductive polyurethane material in a cost effective manner, for example by volumetric dispensing into the recess 110 can be introduced. It does not necessarily have to be supplied with thermal energy to activate the material.

LIST OF REFERENCE NUMBERS

100

Smart card body

102

first electrical component

104

Contact

106

Contact

108

direction

110

recess

112

electrically conductive polyurethane material

200

recess

202

recess

204

chip module

206

adhesive surface

210

outer contact surfaces of the module

Claims (11)

Method for producing an electrically conductive connection between a first electrical component ( 102 ) a chip card ( 100 ) and a second electrical component ( 204 ), wherein the first electrical component ( 102 ) a first contact surface ( 104 ) and wherein the second electrical component ( 204 ) a second contact surface ( 106 ), comprising: - applying a pasty, electrically conductive polyurethane material ( 112 ) on the first contact surface ( 104 ), - solidifying the pasty, electrically conductive polyurethane material ( 112 ), - pressing on the second contact surface ( 106 ) on the cured, electrically conductive polyurethane body ( 112 ), and - fixing the second electrical component ( 204 ) on the chip card ( 100 ) and / or the first electrical component ( 102 ). Method according to claim 1, wherein the electrically conductive polyurethane material ( 112 ) represents a pasty mixture of a polyurethane-based adhesive and metallic particles. The method of claim 2, wherein the metallic particles are silver particles. Method according to one of the preceding claims, wherein the solidification of the electrically conductive polyurethane material ( 112 ) the crosslinking of the electrically conductive polyurethane material ( 112 ) is at least 90% complete. Method according to one of the preceding claims, wherein the second electrical component ( 204 ) by an adhesive connection and / or a clamping connection and / or a latching connection on the chip card ( 100 ) and / or the first electrical component ( 102 ) is attached. The method of claim 5, wherein attaching the second electrical component ( 204 ) on the chip card ( 100 ) and / or the first electrical component ( 102 ) comprises: - applying a thermally activatable adhesive to the second electrical component ( 204 ) and / or the chip card ( 100 ) and / or the first electrical component ( 102 ), - pressing on the second electrical component ( 204 ) on the chip card ( 100 ) and / or the first electrical component ( 102 ), and - heating the thermally activatable adhesive, so that a adhesive bond between the second electrical component ( 204 ) and the chip card ( 100 ) and / or the first electrical component ( 102 ) arises. Method according to one of the preceding claims, wherein the pasty, electrically conductive polyurethane material ( 112 ) by volumetric dispensing onto the first contact surface ( 104 ) is applied. Method according to claim 7, wherein the chip card has a chip card body ( 100 ), wherein the first electrical component ( 102 ) is embedded in the chip card body, wherein the first contact surface ( 104 ) within a recess ( 110 ) of the chip card body is arranged, wherein the on the first contact surface ( 104 ) dispenste amount of pasty, electrically conductive polyurethane material ( 112 ) is selected so that after solidification of the electrically conductive polyurethane material ( 112 ) the cured polyurethane body ( 112 ) over the recess ( 110 protrudes). Method according to claim 8, wherein the quantity of the material applied to the first contact surface ( 104 ) applied pasty, electrically conductive polyurethane material ( 112 ) is selected so that after solidification of the electrically conductive polyurethane material ( 112 ) and pressing on the second contact surface ( 106 ) on the cured, electrically conductive polyurethane body ( 112 ) the cured, electrically conductive polyurethane body ( 112 ) completely in the recess ( 110 ) is recorded. Method according to one of the preceding claims, wherein the pasty, electrically conductive polyurethane material ( 112 ) so on the first contact surface ( 104 ) is applied by solidifying the electrically conductive polyurethane material ( 112 ) an elastic, electrically conductive polyurethane body ( 112 ) that originates from one on the first contact surface ( 104 ) adhesive base in the direction of the first contact surface ( 104 ) tapered away. Chipcard ( 100 ) prepared by the method according to any one of claims 1-10.

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