DE4142392C2 - Method and device for producing injection-molded chip cards with reduced wall thickness in some areas - Google Patents

Description

The invention relates to a method and a device for the production of plastic fittings with area wise reduced wall thickness, especially chip cards, by injecting a molten plastic materials in a molding room and then cooling of the plastic material.

The invention particularly relates to the her Position of plastic fittings where the wall strength significantly in certain areas sets is so that elastic membrane areas or Recesses for receiving thin objects, e.g. B. electronic components, in a wall of an art fabric molding with a wall thickness that is already low can be formed. Because of the limited flow ability of the plastic material could ver thin wall areas with conventional injection molding equipment so far not or only with the acceptance of Quality influences such as weld lines or air pockets be shaped. There were also significant restrictions cations regarding the usable plastic material rials.

The invention is based on the object a method and an apparatus of the aforementioned To create genus that is economical manufacturing of plastic fittings with significant in some areas reduced wall thickness without the restrictions described enable kungen.

This object is achieved by a method and a device with the Features of claims 1 and 15 solved.

The method according to the invention accordingly sees an injection  of the plastic material first in an off gang shape room, its configuration essentially ent that of the fitting without reducing the wall thickness speaks. Since there is no cross-section that hinders the flow path narrowing at this initial state of the shape there are no problems visibly filling the mold space with the plastic material. As a result, there are no restrictions the materials that can be used.

The inventive method also provides that a certain time the distance of certain wall areas of the initial mold space that the or Correspond to areas of wall thickness reduction, ver is reduced so that the plastic material on them Ver areas up to a remaining wall thickness is pushing, which is many times smaller than the wall strength in neighboring areas.

Although by reducing the distance between the certain ones Wall areas of the mold space usually only after substantially complete filling of the initial mold space this process step can already be started be done at a time when the plastic material though the space between the particular wall areas, but not the entire initial mold space has filled. While measures were taken in the former case must be that by reducing the distance displaced volume of material from other areas of the Form space can be included, exists in the second If possible, the displaced volume of material final filling of the mold space.

Appropriate measures to compensate for the repressed Material volume can change accordingly Volume of the mold space at locations outside the specific th wall areas and / or a displacement of the plastic material  be back in the sprue system.

According to a development of the invention, the Lichen elements of the injection mold not only for the Her position of the thin wall areas, but also for on Bedding foreign objects in the plastic mass used. As explained further using the exemplary embodiments there are several ways to do this. To the Variety of ways to illustrate two versions are described.

In one of these embodiments, one moves fix a stamp on the face of the stamp microchip module, as is usually the case for chip cards Application finds, pressed into the plastic mass. On this way, in a single operation, both Module inserted into the card body and fixed as the cavity required for this was also created.

In the second embodiment, the embedding of the Module divided into two steps, one in first step by pressing in the stamp of the hollow space is created in a second, directly connected The module is inserted into this cavity puts. The fixation in the cavity takes place with the help of a hot glue coating provided on the module by the Residual heat of the injection molded card body is activated.

The method according to the invention points towards the known possibilities have a variety of advantages. For example, the end face of the movable Stamps can be structured in almost any complicated manner. By pressing the stamp into the plastic mass you always get an exact impression of these structures. The formation of bubbles, imperfections, blurred contours etc. is completely avoided.  

Since the stamp only after the plastic has flowed in mass is pressed into this is the Molecular Theory uniform across the entire volume of the card, d. H. different molecular orientation leading preferred break lines do not arise. usual Such preferred break lines can be expected, if the plastic mass is injected into the Mold used mold flows around or to the Places where the different plastic flows after Flow around the "obstacle" meet.

Because the thin wall areas by pressing the already one flowed plastic mass is generated, you do not get only the exact shape and wall thickness, even very thin mem branen, in these areas is also compressed the plastic mass increased strength of the like compressed plastic material reached. Just that is of particular interest for chip cards because the Cards in the subsequent printing processes (application of the printed image) as well as in later card use whose loads are exposed.

Further advantages and design variants are the following The following examples can be seen, based on the figure are described.

Show it:

Fig. 1 shows the sectional drawing of a rotationssymmetri's membrane with different wall thickness areas,

Fig. 2 shows an injection mold in fragmentary view ge cut in positions to the time point of mold filling and the reduction in wall thickness,

Fig. 3 shows a chip card blank in plan view,

Fig. 4 shows the section AB of FIG. 3,

Fig. 5 shows the section AB with an inserted chip module,

Fig. 6 shows a device for producing injection-molded cards in a simplified sectional view,

Fig. 7 alternative device elements for manufac turing of smart cards.

Fig. 1 shows the sectional view of a molding 1 made of plastic with different wall thicknesses. The molding 1 is constructed rotationally symmetrical. It has an outer ring 2 , which is reinforced and profiled in such a way that it can be fastened in an annular housing groove for later use. A circular base or a membrane 3 with increased wall thickness is provided in the interior of the molding 1 . Between the outer ring 2 and the membrane 3 , an annular wall thickness reduction 4 is provided, which causes an elastic embedding of the membrane 3 .

Fig. 2 shows a schematically illustrated injection mold, with which the molded part 1 outlined in Fig. 1 can be made.

The injection mold shown comprises, in a manner known per se, a first molded part or a mold plate 12 and a second molded part or a mold plate 13 which can be moved along the center line 10 with the aid of device elements (not shown) for opening the mold. In the closed position shown, the mold parts 12 , 13 define a mold space 11 and 11 'between them. Although the mold space 11 , 11 'in the embodiment shown is arranged rotationally symmetrically to the center line 10 , the invention is of course not restricted to such a position of the mold space. Other non-symmetrical arrangements can also be seen.

In one of the molded parts 12 , 13 , in the present embodiment from the molded part 13 , an arrangement consisting best of an outer core member 14 and an inner stamp member 15 is provided. The elements 14 , 15 can be moved relative to each other and to the molded part 13 and have free end faces that limit or define the molding space 11 be.

As already mentioned, in the present embodiment, the injection mold is used to produce a disk-shaped molded part with an annular cross-section thinning near its outer circumference. The outer core member 14 may accordingly have a cylindrical configuration with an axis that coincides with the center line 10 of the mold space 11 .

The outer core element 14 is, as indicated by the arrows 5 , 6 , movable between a first and second position relative to the opposite molded part 12 , which are each limited by suitable means, not shown, stop. In the starting position (on the right in the drawing), the distance "S" between the free end face of the core element 14 and an opposite wall area of the mold space 11 is relatively large, since the core element 14 is substantially sunk in the molded part 13 . In the area of the core element 14 there is thus no cross-sectional constriction, which could prevent the material from flowing in from a central sprue, not shown, to the outer boundaries of the molding space 11 . The mold space 11 in this position of the core element 14 has a configuration which essentially corresponds to that of the molded part to be manufactured without a reduction in wall thickness and is therefore also referred to below as the initial mold space 11 '.

In the second position shown in the drawing on the left, the core element 14 has been moved into the mold space 11 , as a result of which the distance between its free end face and the opposite wall area of the mold space 11 has been reduced to a dimension “s”. This dimension "s" corresponds to the desired reduced wall thickness on the fitting to be manufactured.

Although other suitable devices can be provided, an arrangement of interacting first wedge surfaces 21 , 22 on the end face of the core element 14 facing away from the mold space 11 or on one serves to control the movement of the core element 14 between the first and second positions between the molded part 13 and a support plate 17 slidably arranged control element 16 . The wedge surfaces 21 , 22 cause the translational back and forth movement of the control element 16 (see arrow 9 ) into a movement of the core element 14 in the direction of arrows 5 and 6 respectively. It is understood that other suitable facilities, e.g. B. a solenoid or hydraulic piston / cylinder device can be provided.

The movement of the control element 16 in the direction of arrow 9 can by any suitable actuating device (not shown), for. B. Piston cylinder direction, depending on the command of a control device, also not shown.

The arrangement of the cooperating first wedge surfaces 21 , 22 is such that when the control element 16 moves in one direction (to the right in the drawing) the core element 14 assumes the first or starting position, while when the control element 16 moves in the opposite direction, this Core element 14 is brought into the second position on the left in the drawing.

A second pair of cooperating wedge surfaces 23 , 24 is seen on the inner stamp element 15 or control element 16 . The second wedge surfaces 23 , 24 are oriented with respect to the first wedge surfaces 21 , 22 , so that the movement of the control element 16 in one direction triggers a movement of the stamp element 15 in a direction which is opposite to that of the core element 14 , When the control element 16 is shifted to the left in the drawing, the stem element 5 therefore experiences a movement in the direction of arrow 7 away from the opposite molded part 12 , so that the distance between the free end face of the stamp element 15 and the opposite wall area of the Molding space 11 slightly increased, while at the same time the distance between the free end face of the core element 14 and the opposite wall area of the molding space 11 is reduced.

By suitable adjustment of the inclination of the first and second wedge surfaces 21, 22 and 23, 24 can be achieved that the effect achieved by the movement of the stamping element 15 increasing the volume of the mold space 11 is substantially the decrease in volume due to the movement of the core element 14 in the second position speaks accordingly. In this way it can be achieved that the total volume of the mold space 11 is changed in wesent union both in the first and second positions of the core element 14 . However, it goes without saying that the invention is not restricted to an essentially complete volume compensation. Rather, if desired, the sub-volumes displaced or created by the elements 14 , 15 can differ from one another, as a result of which special effects on the shaped piece to be produced, eg. B. achieve a material compression.

The operation of the device described above is as follows. Via the central sprue system, not shown in the drawing, molten plastic material is injected into the starting mold space 11 ', the core element 14 and stamp element 15 being in the positions on the right in the drawing, so that the material is not significantly impeded by the large gap " S "can flow to the outer areas of the initial mold space 11 'and thus its problem-free complete filling is guaranteed. Immediately after completion of the filling process, the control device sends a command to the actuating device of the control element 16 , on the basis of which the control element 16 is moved in a direction in the drawing to the left along the arrow 9 . The movement of the control element 16 has the result that the core element 14 is brought in the direction of arrow 5 into the second position on the left in the drawing, thereby displacing the material located between its end face and the opposite wall of the molding space 11 . At the same time, the displacement of the control element 16 causes a movement of the inner stamp element 15 in a direction along the arrow 7 away from the opposite molded part 12 , as a result of which the distance between its free end face and the opposite wall of the molded space 11 increases somewhat by the core absorb element 14 displaced volume.

The position of the parts shown on the left-hand side of the drawing is maintained until the material in the mold space 11 has cooled and the molding obtained after opening the mold has been ejected from the mold space by suitable mechanical or pneumatic means. In the effective area of the outer core member 14 then remains in the fitting a gap "s" speaking wall thickness, which, if desired, can be much smaller than the wall thickness at adjacent areas of the fitting. Experiments have shown that the method according to the invention easily reduces the initial wall thickness of e.g. B. 0.8 mm to 0.15 mm or less, without weld lines or air pockets occurred on the molded parts. Since the mold filling process is not restricted by any narrowing of the cross section of the mold space, practically all thermoplastic materials can be processed with the method according to the invention. The relevant restrictions that exist in conventional methods for spraying thin wall thicknesses are eliminated.

It is understood that the invention is not limited to the ge number of core and stamp elements 14 , 15 and their arrangement with one another and with respect to the mold space 11 , but any arrangement of one or more wall thickness reducing core elements 14 with one or more Stamp elements 15 can be provided. Instead of a stamp element 15, it can also be provided to change the volume that the material volume displaced by the core element 14 is led back into the sprue system through the still plastic core of the material present in the molding space. Other, volume-changing facilities, e.g. B. a membrane-like flexibility of a wall region of the mold space can also be provided.

In the embodiment shown, the movement of the elements 14 , 15 takes place essentially parallel to one another to the center line 10 . The invention is not limited to one of the direction of movement. Rather, the movements of the individual elements between their respective end positions can be adapted to the respective application and aligned differently.

Fig. 3 shows a further shaped piece, which in this case is designed as a chip card blank 26 and which can be produced in a particularly advantageous manner using the method according to the invention. The card blank 26 has a recess 27 with the steps 28 and 33 , in which a chip module is inserted at a later time.

The section AB of FIG. 3 is shown schematically in FIG. 4. For the sake of clarity, the exact reproduction of the proportions has been omitted. Usually, the outer dimensions of such chip cards are approximately 85 mm × 54 mm, the thickness is 0.76 mm, the membrane 28 at the bottom of the recess 27 has a wall thickness of approximately 100 μm. The outer diameter of the recess 27 is approximately 15-20 mm, the shape of the recess can vary as desired both with regard to the outer contour and in the gradation. So z. B. rectangular, square or oval outer outline is known. The depression itself can also have a plurality of gradations or be designed in the form of a lens in the inner region.

Fig. 5 shows the section AB of the map area with a chip set, module 44. The chip module consists of a carrier film 29 , on which metallic contact surfaces 30 are provided, via which, when using the chip card 26 , can be communicated with the integrated circuit arranged in the cast resin pill 31 , or chip for short (not shown). The chip module 44 is provided with an adhesive layer 32 , with the aid of which the module is fixed in the recess 27 .

Fig. 6 shows an injection mold for the production of chip cards using the method according to the invention. The device essentially consists of a lower mold half 35 and an upper mold half 36 . Between these two mold halves, the mold space 38 is provided, which has the shape of the later chip card, but without the recess 27 shown in FIG. 4. The two mold halves 35 and 36 have an injection channel 39 , through which the plastic material flows into the mold. Furthermore, a stamp guide 46 is provided, via which the stamp 40 can be inserted into the molding space 38 .

In the simplest case, the injection of the chip card 26 could now take place so that the stamp 40 is inserted so far into the stamp guide 46 that the end face of the stamp ends with the edge to the molding space 38 . In this arrangement, the plastic material is pressed in via the injection channel 39 in a first step. After the molding space is largely filled with plastic material, the stamp 40 is pressed into the molding space or the plastic mass located there so that the end face of the stamp 40 is imaged in the plastic mass or the stepped depression 27 is provided. The plastic material displaced by the stamp 40 is, as already described, either displaced into the mold space not yet filled with plastic material or pressed back into the injection channel 39 . After completion of the injection molding process and sufficient cooling of the plastic compound, the two mold halves 35 and 36 are opened and the molding or chip card blank 26 is removed from the mold. The removal can be mechanically supported by further lowering the punch 40 instead of a separate ejector.

When carrying out this method, it is of course necessary to form the end face of the stamp 40 differently from the embodiment shown in FIG. 6 in accordance with the recess 27 . That is, the end face has a step, as shown in FIG. 7 a, with which the membrane 28 is formed. The shape of the stamp itself then corresponds to the expanded area of the depression or the outer contour of the recess 27 .

In addition to the corresponding design of the stamp face, the surface can of course also be influenced in a targeted manner, for example in order to produce, as is necessary in the present case, special surface roughness of the annular step 33 in the later chip card blank. By specifically roughening this surface, better adhesion of the adhesive 32 is achieved when the chip module is being installed.

The device shown in Fig. 6 has further on direction elements, with the help of the position of the chip card blank described in the introduction and the simultaneous embedding of the chip module is possible.

The upper mold half 36 is supplemented by a further guide plate 37 , which also has a stamp guide 46 . The punch 40 can thus be pressed through the guide plate 37 and the upper mold half 36 into the mold space. Between the upper mold half 36 and the guide plate 37 , a transport channel 34 is provided, which crosses the stamp guide 46 and over which a film strip 41 can be transported past the end face of the stamp 40 . The foil strip 41 is designed as an “endless strip” and contains the chip modules 44 in a row.

In a modification of the simplest embodiment variant described at the beginning, the stamp 40 shown in FIG. 6 has no gradation, but a flat surface. In addition, one or more suction air channels 43 are provided, with the aid of which the film strip can be sucked onto the face of the stamp.

The map is now made as follows:
In a first step, the film strip 41 is arranged in front of the end face of the stamp 40 in such a way that a chip card module 44 is positioned in front of it. By lowering the stamp 40 in the direction of the molding space 38 (arrow 42 ), the chip module is pressed into the stamp guide of the molded part 36 and punched out of the film strip 41 . The die-cut chip module is sucked through the suction channels 43 and thus held on the end face of the stamp. The punch 40 is now lowered in the direction of the molding space 38 so that the lower edge of the chip module is approximately flush with the upper edge of the molding space 38 , ie the chip module does not yet protrude into the molding space. In this position, the plastic material is injected via the injection channel 39 . After the mold space has been filled sufficiently, the stamp is pressed into the plastic mass together with the chip module, to the extent that the flat end face of the stamp 40 is flush with the subsequent card surface.

After the plastics material has cooled sufficiently, the mold is opened, ie the mold halves 35 and 36 are moved apart and ejected from the mold by reactivating the stamp 40 . The separation of the card from the plastic mass located in the injection channel 39 is carried out in a known manner either by tearing or cutting with the aid of cutting elements, not shown.

After the two mold halves 35 and 36 have been closed , the stamp 40 is pulled back into the starting position and the area of the film strip provided with the punching 45 is moved further until a chip module 44 is positioned in front of the stamp 40 again.

The card manufacturing process shown in FIG. 6 thus enables the production of injection-molded chip cards with simultaneous embedding of the chip module. Tests have shown that pressing the chip module into the injected plastic compound is relatively unproblematic as long as the outer shape of the chip module is simply structured and the module can be subjected to mechanical loads. In the case of complex structured modules or when using large chip components (such as microprocessor chips), it may be advisable to create the cavity in the card before embedding the module. This is done in a simple manner by modifying the process sequence described for FIG. 6 and using a stamp 40 ver, with which these additional functions are to be accomplished.

Fig. 7a shows a possible Ausführunsform of such additional functions equipped die 40. The stamp 40 consists of three stamp elements 47 , 48 and 49 which slide into one another. The stamp 40 is used in the form shown in FIG. 7 a for pressing in the depression 27 . For this purpose, the stamp is brought out through the foil punching 45 of the foil strip 41 through to the molding space 38 , the plastic material is injected into the molding space and, as described at the beginning, pressed into the molding compound.

Now that the stepped depression 27 has been embossed into the card body, the stamp 40 is withdrawn into the guide plate 37 . In addition, the stem element 48 is moved back until the end face of the element 48 is flush with the end face of the element 49 . Furthermore, the pin 47 is pulled back into the position shown in FIG. 7b and fixed. In this position there is an air channel opening into the center of the stamp end face, which allows the chip module 44 to be sucked in through a bore in the element 48 and a longitudinal groove 50 provided in the element 49 .

After the stamp 40 has been brought back by retracting the elements 47 and 48 into the arrangement shown in FIG. 7b and the film strip 41 has been moved one position further, the stamp 40 is pressed again in the direction of the mold space, as described initially, a chip module 44 punched out of the film strip 41 and placed in the previously created stepped depression. The chip module 44 equipped with an adhesive layer 32 is now pressed with the stamp 40 into the recess 27 . The residual heat of the plastic material activates the hot glue and fixes the module in the card body.

After sufficient cooling, the mold halves 35 and 36 can be opened again and the card body removed from the mold.

Claims (17)

1. Method for producing chip cards with an injection-molded card body with a recess in which a chip module is located, by injecting a molten plastic material into a molding space and then cooling the plastic material, characterized by the following process steps:

• Production of the card body by injecting molten plastic material into an initial molding space, the configuration of which essentially corresponds to the card body without a recess,
• - Reducing the distance between certain wall areas of the initial molding space with a movable stamp to form the recess after the plastic material has flowed into at least the areas of the wall areas to be changed, wherein
• - The plastic material that has flowed in is displaced from the wall areas, between which the distance is reduced, into the adjacent areas of the molding space.

2. The method according to claim 1, characterized draws that with decreasing the distance of certain wall areas only after essentially complete filling of the initial mold space started becomes. 3. The method according to claim 2, characterized records that be parallel to the reduction certain wall clearances in other areas of the form room wall distances are increased, the areas with the increased wall distances that from the first named areas on displaced plastic material to take.   4. The method according to claim 2, characterized records that the material in the sprue system is ousted. 5. The method according to claim 1, characterized records that by the wall thickness ver reduction caused material displacement in the mate rial supply is already taken into account. 6. The method according to claim 1, characterized records that in the area of wall thicknesses reduction to the shape that is still in the molding space piece an additional element is used. 7. The method according to claim 6, characterized shows that the reduction in wall thickness by Pressing in the additional element, preferably by Pressing a chip module is generated. 8. The method according to claim 7, characterized records that the additional element with the help a movable stamp pressed into the fitting becomes. 9. The method according to claim 6, characterized records that the embedding of the additional element takes place in two steps, in the first step the cavity required for the molded body by pressing of the movable stamp is created and in the second Step of embedding the additional element is carried out. 10. The method according to claim 9, characterized records that both process steps with the same movable stamp.   11. The method according to claim 9 and 10, characterized records that the shape of the stamp face in the first process step to create the shape of the the recess is adjusted and for the second procedure is changed in such a way that the stamp for Punching out, transporting and embedding in the recess tion of the fitting is suitable. 12. The method according to claim 6-9, characterized records that the additional element is a hot glue has coating that after insertion into the Deepening of the fitting by means of the residual heat of the Fitting is activated. 13. The method according to one or more of claims 6-12, characterized by the following process steps:

• - Positioning a film strip with chip modules in front of the stamp face;
• - sucking the film strip onto the stamp by activating a source of suction air,
• Lowering the stamp in the direction of the molding space and simultaneously punching out a chip module from the film strip,
• - positioning the chip module in the area of the interface of the molding space,
• - injecting the plastic material into the molding space,
• further lowering of the stamp or pressing of the chip module into the surface of the shaped piece after the molding space in the area of the stamp is largely filled with plastic material,
• - complete injection of the molding space, as far as voids in the molding space have to be filled with plastic material,
• - cooling of the molded part until the plastic material solidifies,
• - Open the injection mold and remove the molded part.

14. The method according to one or more of claims 6-12, characterized by the following method steps:

• Lowering of a stamp with a stamp face adapted to the depression to be created up to the area of the mold space surface,
• - injecting the plastic material into the molding space,
• - Further lowering the stamp into the plastic mass of the molding space to form the recess to be produced in the molded part,
• - further injection of the plastic mass until all cavities in the molding space are filled,
• - cooling the molded part until the plastic mass solidifies,

15. Injection molding device for carrying out the method according to claim 1, with a mold which includes at least one mold space and the mold parts movable relative to one another and at least one stamp movable between a first and second position in and out of the mold space region, characterized in that
the molding space largely corresponds to a chip card without a recess, and
the end face of the movable stamp corresponds to the recess to be created in the card body. 16. The apparatus according to claim 15, characterized in that the Stamp consists of several individual parts that change the shape of the stamp, preferably the stamp face. 17. Chip card, produced by the method according to one of claims 1 to 14, characterized in that the card body one or has multi-stage recess for receiving a chip module and the Molecular orientation in the vicinity of the module almost the orientation in the corresponds to the remaining map area.