WO2000025264A1

WO2000025264A1 - Hot-melt adhesive component layers for smart cards

Info

Publication number: WO2000025264A1
Application number: PCT/EP1999/007683
Authority: WO
Inventors: Liane WÜSTRICH; Paul Ranft; Jürgen GRÜTZNER; Uwe Kolb
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1998-10-22
Filing date: 1999-10-13
Publication date: 2000-05-04
Also published as: CA2347818A1; DE19848712A1; EP1123535A1; JP2002528907A; KR20010080890A

Abstract

The invention relates to the utilization of thermoplastic hot melt adhesives for the production of component layers in smart cards or for the production of electronic transponders with the aid of a low pressure injection molding process at pressures ranging between 1 and 50 bar. Preferably, hot melt adhesives based on polyamide, polyurethane, polyester, atactic polypropylene, EVA copolymers or low molecular weight ethylene copolymers or the mixtures thereof are used in said method.

Description

"Component layer for smart cards made of hot melt adhesives"

The invention relates to a multilayer composite body, a process for its production and the use of thermoplastic hot melt adhesives for the production of this composite body.

The present invention is primarily, but not exclusively, concerned with the production of so-called smart cards. A smart card is generally understood to mean a multi-layered shaped body in the form of a plastic card, which is usually imprinted with information and / or advertising and / or with security features, such as, for. B. a photo of the cardholder, a magnetic strip, an identification mark in the form of a hologram or the like. This smart card usually consists of a plastic card laminated on one or both sides. A so-called module is embedded in the card body of the smart card, the essential component of which is an electronic circuit (chip). This chip can sit on a carrier plate which, in a specific embodiment, is provided with a plurality of electrically conductive surface segments. This segmented electrical contact surface is accessible from the outside, so that information such. B. data and identification features can be exchanged via these contacts with external computers and / or control devices. Newer card types contain an antenna electrically connected to the chip in the card body, so that both electronic information exchange and the energy supply of the chip in the card carrier can take place without contact via this antenna. Smart cards of this type are used or provided as telephone cards, authorization cards for mobile messaging devices, check cards in monetary transactions, authorization certificates for health insurance companies, driver's licenses, train or bus tickets. The user pushes the contactless smart card into a card reader or passes it at some distance past the reader, which connects to the electronic circuit in the smart card via a corresponding antenna device. In this way, e.g. B. with a telephone card or a check card or a train ticket, an existing cash balance can be checked, an identity can be determined or another data exchange can be carried out.

Manufacturing processes for contactless smart cards are known in principle. For example, WO-A-98/09252 describes a multi-stage manufacturing process. First, the so-called component layer or card body is provided with openings, depressions or the like. Cavities, then the electronic components to be arranged in the card body are inserted into these cavities, then the card body is coated with an adhesive such that the cavities are filled and the adhesive forms a substantially flat surface. A cover film is then applied to the surface of the adhesive that has not yet set or hardened and is therefore still plastically deformable. The cover film is then held with its surface facing away from the card body on a shaped surface in such a way and for as long during the curing of the adhesive that the outer contour of the cover film and thus the outer contour of the finished smart card corresponds to the contour of the molding surface. A cold-curable adhesive, in particular an epoxy adhesive, is proposed as the adhesive. In order to prevent this adhesive from shrinking, it must be filled with a filling material such as glass, quartz or the like. This manufacturing process involves many work steps and is time-consuming and therefore very cost-intensive.

EP-A-0 692 770 describes a method in which the chip and the antenna are introduced into the cavity of an injection mold, whereupon a thermoplastic material is injected into this mold, optionally in several steps. Typical thermoplastic material such as. B. PVC, ABS (acrylonitrile-butadiene-styrene terpolymer), polyethylene terephthalate (PET), polycarbonate (PC) or polyamide (PA) are proposed. Such injection molding materials require very high temperatures and high pressures of z. B. 700 kg / cm ² . Such high pressures and temperatures are, however, very poorly suited for the sensitive electronic circuits to be embedded, so that they are often damaged.

EP-A-0 709 804 proposes, in a multi-stage injection molding process, first to insert a plastic disc into the injection mold on which the antenna is placed. Then a liquid plastic material (specifically ABS, PC, PET, polyamide or reactive resins curable at higher temperatures such as polyurethane, epoxy-phenolic resins are distributed over the surface of the antenna, leaving the antenna connections free. A plastic layer is then placed over the antenna, which the Hole in the card closes This plastic layer has a recess in which the electronic chip is inserted so that it the antenna connections are in electrical contact. This procedure also requires high temperatures and high pressures for the injection molding steps, in addition, further work steps are required to insert the electronic circuit into the card body, to fasten it and to electrically connect it to the antenna.

JP-A-08 276 459 describes a manufacturing method for contactless smart cards, in which the component carrier consists of a glass fiber reinforced epoxy resin which has a recess and optionally contains conductor tracks, also for forming the antenna. The electronic chip is inserted into the recess of the component layer. This entire component is then placed in an injection mold and, after closing, a liquid, thermosetting plastic material is injected into the mold at low pressure and cured there. A thermosetting epoxy resin is specifically proposed for this purpose. It takes 4 to 5 minutes to cure the epoxy resin. After removing the casting from the casting mold, post-curing by heating to a certain temperature and for a certain time is necessary. No specific information is given about this post-curing.

EP-A-0 350 179 describes a manufacturing process for smart cards and similar electronic brands (token) using a reaction injection molding process. The electronic circuit is encapsulated by a layer formed by the reaction injection molding material. The cover foils of the two flat sides of the card are fed to the mold during the injection molding in such a way that they simultaneously serve as mold release agents for easier removal of the hardened card body from the injection mold. Specific information about the Settlement of the plastic for the reaction injection molding process are not made, it is only said that any plastic material or plastic mixture can be used that will cure under reaction injection molding conditions. Reaction injection molding machines are known to be expensive and complex because of the precise metering devices involved.

EP-A-0 846 743 describes a thermoplastic, thermosetting, self-adhesive adhesive film for implanting electrical modules into a card body, which is provided with a recess into which an electronic module is to be placed, which has a plurality of contact surfaces on the first side and on the opposite side has an IC chip, the connection points of which are connected to the contact surfaces via electrical conductors. The adhesive film should be made up of a thermoplastic polymer, one or more tackifying resins and / or epoxy resins with hardeners and possibly also accelerators. These adhesive films must be cured in the heat at about 150 ° C for 30 minutes.

JP-A-05 270 173 describes a method for producing laminated plastic sheets for card blanks. For this purpose, two rigid PVC rigid films are coated with a moisture-curing polyurethane hot-melt adhesive with a 5 to 50 μm thick layer at 100 to 120 ° C. and pressed for 10 seconds under a pressure of 5 kg / cm ² . One of these foils has a recess or a cavity created by thermoforming for receiving the microprocessor to be inserted later. These fabrics are then left without pressing for several hours at room temperature so that the Adhesive cures to form a card base material that can be processed into the finished smart card in further processing steps.

The task was therefore to develop a gentle, quick and simple method for producing smart cards which enables inexpensive large-scale production of such smart cards. The achievement of the object according to the invention can be found in the claims. It consists essentially in the use of thermoplastic hot melt adhesives for the production of the component layers of smart cards and in a process for the production of these smart cards in which the thermoplastic hot melt adhesives can be used at low temperatures and low pressures in the low pressure injection molding process.

The thermoplastic hot-melt adhesives used are preferably the low-melting polyamides based on polyaminoamides, thermoplastic polyurethanes or atactic polypropylene or a mixture thereof for the production of the component layer. These thermoplastic hot melt adhesives are characterized by a low viscosity of around 100 to 100,000 mPa.s at the processing temperature. As a result, they can be used in the low-pressure injection molding process at pressures between 1 and 50 bar, preferably at injection pressures between 10 and 30 bar. The processing temperatures depend on the composition of the hot melt adhesive material, they are between 80 ° C and 250 ° C, preferably between 100 ° C and 230 ° C. The preferred polyamides to be used usually have a viscosity below 10,000 mPa.s. at 210 ° C. Particularly preferred areas Before the processing viscosities at 210 ° C are between 1,500 and 4,000 mPa.s, this viscosity is usually measured with a Brookfield viscometer of the "RVDV II" type with thermo equipment.

In special cases, instead of the above-mentioned thermoplastic hotmelt adhesives, reactive, moisture-crosslinking polyurethane hotmelt adhesives can also be used. Because of their sensitivity to moisture, the moisture-reactive polyurethane hotmelt adhesives require more effort during application, but their advantage lies in the significantly lower viscosity at the processing temperatures; reactive polyurethane hotmelt adhesives generally have viscosities of <25,000 mPa.s at 130 ° C, preferably these viscosities are even below 15,000 mPa.s and very particularly preferably below 10,000 mPa.s at 130 ° C., the viscosity usually being measured using a Brookfield viscometer of the "RVDV II" type with thermoset equipment. An advantage of the use of moisture-curing polyurethane hotmelt adhesives is their low melting point, which is usually below 100 ° C, preferably below 70 to 80 ° C, so that even very temperature sensitive circuits can be embedded with these hot melt adhesives and also very temperature sensitive laminating films v can be used. Through their post-crosslinking with moisture, a particularly resistant and temperature-resistant bond is created between the component layer and the base and cover films.

By using the thermoplastic hot-melt adhesive to produce the component layer, the subsequent milling out of the space required for receiving the chip or chip and Antenna can be saved because these parts to be poured can be inserted into the corresponding casting mold before the base body is finished. During the subsequent encapsulation process, the chip or chip and antenna are enclosed by the base body (component carrier) so produced that an additional fixation is unnecessary and any necessary padding or filling of the electronic components no longer has to be carried out subsequently. It is also possible to dispense with an additional adhesive application to the component carrier when applying the printable or printed base and cover film, since this is made of adhesive itself and, if necessary after suitable activation by heating, a secure connection to the base and / or creates cover foils.

According to the invention, all thermoplastic reactive and non-reactive hot melt adhesives can be used for the production of the card base body, as long as they can be processed at processing temperatures between 80 ° C and 250 ° C, preferably between 100 ° C and 230 ° C in the low pressure injection molding process, i.e. their processing viscosity should be between 100 and 100,000 mPa.s. The pressure range for the low-pressure injection molding process is in the range from 1 to 50 bar, a range for the injection molding between 10 and 30 bar is particularly preferred. This ensures that the inserted chips or otherwise used electronic storage media are gently rinsed and cannot be damaged and destroyed by high injection pressures (500 to> 1000 bar) as in the regular injection molding process. Depending on the type of base and cover film used for the finished card and the requirements for stiffness or elasticity of the card body and its possible temperature loads, the hot melt adhesives can be made from the groups known per se: polyamide (especially polyaminoamide based on dimerized fatty acids), polyurethane, polyester , Ethylene-vinyl acetate (EVA) copolymer, low molecular weight polyethylene copolymer, atactic polypropylene (APP) or combinations thereof. As already mentioned above, it can be advantageous in special cases to use reactive hot melt adhesives based on moisture-reticulating polyurethanes instead of the aforementioned thermoplastic hot melt adhesives.

All of the films known in principle for this purpose can be used as the base or cover film, for example films based on polyester, in particular polyethylene terephthalate (PET), polyvinyl chloride (PVC), acrylonitrile-butadiene-styrene (ABS), polycarbonate (PC) ) or polyimide. These foils usually have material thicknesses of up to 100 μm, the foil thicknesses are preferably in the range between 30 and 70 μm.

The manufacturing process according to the invention can be carried out in various ways. On the one hand, the chip and, if applicable, the associated antenna can first be inserted into the mold of the injection molding system. B. present on a carrier film. After closing the mold, the hot melt adhesive is then injected. After briefly cooling, the mold can be opened and the component layer thus produced can be removed from the mold. For the subsequent lamination with a base and / or cover film, none is used WO 00/25264 -, _Q PCT / EP99 / 07683

Further adhesive application is required because the matrix of the card carrier layer itself functions as an adhesive; the foils only have to be pressed with the component layer, if necessary with heating.

Alternatively, a thin film of the hot melt adhesive can be inserted into the injection mold, the electronic component and the antenna can be placed thereon. The mold is then closed and the electronic components are completely encased by injecting further hot-melt adhesive material. For the lamination with the base and / or cover film, no further application of adhesive is likewise necessary, since here too, if necessary with heating, the films can be pressed with the component layer and are thus permanently connected to the layer. The layer thickness of the hot-melt adhesive matrix including the cast-in chip is generally between 400 and 600, preferably 500 μm, but can be thinner or thicker depending on the chip type.

In a particularly preferred embodiment, a low-pressure processing system from Optimel Schmelzgußtechnik can be used to embed the electronic component and the antenna in the matrix of the card carrier layer made of the hot-melt adhesive. The preferred embodiment of the injection mold is shown in Figures 1 to 3. The shows

Fig. 1 is a plan view of the lower part of the injection mold

Fig. 2 is a side view of the upper part of the injection mold

Fig. 3 is a detailed view of the upper part. 1, the lower part 1 of the injection mold has a recess 2, the length and width of which correspond to the dimensions of the upper part of the injection mold. In addition, the lower part of the injection mold contains the injection channel 3, which is designed so that the hot melt adhesive can fill the entire mold completely and without bubbles in the shortest possible cycle times. In addition, the shape of the injection channel is designed so that the sprue remaining on the card body can be easily removed after the card body has solidified.

Fig. 2 shows a cross-sectional view of the upper part 4 of the injection mold on the section line AB of Fig. 1. In its upper edge region, this upper part has a projection 5, so that when the upper part engages in the recess 2 of the lower part a completely closed space in the Injection mold is created. The recess 6 of the upper part 4 corresponds in its length and width dimensions to the card carrier layer to be manufactured, the depth of the recess 6 corresponds to the thickness of the component layer to be manufactured.

FIG. 3 shows a detailed view C of FIG. 2, in which the recess 6 for the card carrier layer is shown in detail.

Alternatively, in a continuous manufacturing process, the base and top layer foils of the injection mold can be fed simultaneously with the chip and optionally with the antenna, which can optionally also be applied in a copper foil on a thin flexible film. After closing the mold, the hot melt adhesive is again injected. After briefly cooling and opening the mold, the finished laminate can be transported further. This procedure has the advantage that the base and top layers can simultaneously serve as mold release agents in the injection mold. In all of the above-mentioned manufacturing processes, the base film and / or cover film can be produced in a preceding or subsequent production step with customary information and / or advertising imprints and / or security features such as. B. a photo of the card holder, a magnetic stripe, an identification mark in the form of a hologram or the like.

The advantages of the use of thermoplastic hot melt adhesives according to the invention for producing the component layers compared to the prior art are:

• There is no need for support material to be produced separately in the normal injection molding process

• Milling work to create the cutouts for the chip and the antenna is omitted

• Furthermore, there is no need to glue the chip and antenna separately into the cutouts

• After lamination with base and cover film, there is no "read through" of the unevenness of conventional production, since the card carrier layer has a very smooth surface on the one hand and on the other hand acts as an adhesive itself.

Although the main field of application of the invention is the production of cards containing contactless electronic circuits (smart cards), this technique can also be used for the production of transponders for the automotive industry, in mechanical engineering and in container construction for controlling processes.

Claims

claims

1. Use of thermoplastic hot melt adhesives for the production of component layers of smart cards.

2. Use of thermoplastic hot melt adhesives for the production of transponders.

3. Use according to claim 1 or 2, characterized in that the hot melt adhesive is based on polyamide, polyurethane, polyester, atactic polypropylene (APP), ethylene-vinyl acetate (EVA) copolymers, low molecular weight polyethylene copolymers or mixtures thereof .

4. A process for the production of electronic circuits containing card bodies (smart cards), characterized in that a thermoplastic hot-melt adhesive is used as the component layer material, the processing viscosity of which is between 100 and 100,000 mPa.s (Brookfield, RVDV II + Thermosel).

5. The method according to claim 4, characterized in that the component layer in the low pressure injection molding process at pressures between 1 and 50 bar and processing temperatures between 80 ° C and 250 ° C, preferably between 100 ° C and 230 ° C is cast.

6. Multi-layer card body, characterized in that the electronic circuit-bearing layer consists of a thermoplastic hot melt adhesive.