MXPA98009557A - Carrier element for a chip semiconduc - Google Patents

Abstract

The present invention relates to a carrier element for a semiconductor chip, it is intended to serve both to incorporate in chip cards, as well as to weld in platinum with the DMS technique. For this, the copper lining of a plastic film (1) is structured by corrosion in such a way that the contact surfaces (3) are formed in one piece with the conductive tracks (4) that end at the edge of the element carrier, which allow a soldier to follow

Description

CARRIER ELEMENT FOR A CHIP SEMICONDUCTOR FIELD OF THE INVENTION The invention relates to a carrier element for a semiconductor chip, in particular for incorporation in chip cards, in which a metal sheet is laminated and structured in such a manner on a non-conductive sheet, that lines of contact surfaces extending in the direction of the opposite major edges of the carrier element, and the semiconductor chip is disposed on the side of the non-conducting sheet opposite the metal sheet and is electrically connected to the contact surfaces by means of recesses through of the non-conductive film.

BACKGROUND OF THE INVENTION This type of carrier elements are known, for example, from German Patent DE 34 24 214 C2 and are used to a large extent in chip cards. For its manufacture, a non-conductive film, which currently consists preferably of epoxy resins reinforced with glass fiber, is lined with a conductive sheet, preferably made of copper with a refined surface. In this conductive sheet structures are corroded, which form isolated contact surfaces, which are arranged in two series parallel to each other on the longitudinal sides of a central surface. Generally, one of the external contact surfaces is formed in one piece together with the central contact surface. Before the rolling process, perforations are made in the non-conductive film, which allow an access to the contact surfaces, in order to be able to electrically connect a semiconductor chip with the contact surfaces, so that the chip can be contacted through the contact surfaces by a reading device. It is also possible to provide a central bore for the housing of the semiconductor chip, as is the case, for example, in German Patent DE 34 24 241 C2, in order to reduce the total height of the carrier-chip element arrangement. Most known carrier elements currently have an approximately rectangular base surface, with the two series of contact surfaces extending along two opposite edges of the carrier element. Carrier elements of the type described above are also known from French Patents FR-A-2617668 and FR-A-2684236. In these carrier elements, the contact surfaces are connected with narrow conductive paths, which lead to a common connection, in order to be able to effect in a simple manner a superficial galvanic refinement of the contact surfaces. Previously, semiconductor chips for chip cards almost exclusively fulfilled specific storage functions and, due to their serial data entry, were only suitable for use in chip cards. However, with the increasing progress of chip cards with microprocessor functions, the semiconductor chips used for this purpose had a more general use, since microprocessors with serial input, in particular those with special coprocessors, are also used when they are not packaged. a chip card. They can also be incorporated, for example, in PCMCIA cards or used in general in platina. The currently preferred joining technique between semiconductor chip and a platinum is to weld according to the DMS (Surface Mounted Device) technology. In this case, a solder paste is applied by sieve pressure on the platinum and then the semiconductor chip, which is housed as DMS, is placed on top. Next, the platinum is placed in a furnace to melt the weld and thus obtain a bond between the platinum and the semiconductor chip. The chip housings with DMS possibilities have specially formed connections, which allow an automatic equipped and a welding process also automatic. The union by soldier must be reliable and be made in defined places, without the soldier to escape and short circuits result, or, do not get a good contact. In contrast, the carrier elements for current chip cards have relatively large surface contacts, which serve primarily to obtain a secure contact with the feeler tips of a reading device. In particular, the ISO 7816 standard determines the minimum size and position of the contact surfaces. Therefore, for various applications it is necessary to provide various accommodations, or chip carriers, which produces an increase in the cost of manufacturing due to various manufacturing processes, logistics, materials, etc. By the Swiss Patent CH 654 A5 is known to provide a carrier element for chip cards also for another type of mounting, for example for incorporating into hybrid circuits. In said carrier element, however, the contact surfaces for the assembly of the chip and the connections formed in one piece, are in different planes, so that an expensive manufacturing is required. In addition, the connections for the direct contact of the semiconductor chip are foreseen, so that they can not also be used as welding tabs, since the chip would be damaged. European Patent 0 311 435 A2 also describes a carrier element for chip cards of a non-conductive metal-lined substrate, in which the metal sheathing is structured on contact surfaces. The conductive conduits forming contacts are formed in one piece with the contact surfaces. However, these connections serve for the direct contact of a semiconductor chip disposed in a recess of the substrate and, for this purpose, they reach the area of the recess. Therefore, in this case the connections can not be used as welding flanges either.

OBJECTIVES AND ADVANTAGES OF THE INVENTION Therefore, the objective of the present invention is to provide a carrier element for semiconductor chips, which complies with current ISO standards for chip cards and which also presents DMS possibilities. The objective is achieved by a carrier element in accordance with claim 1. Advantageous embodiments are indicated in the sub-claims.

In the production of a copper-coated epoxy glass carrier element, according to the invention, not only contact surfaces but also narrow conductive tracks connected in one piece with them are corroded. The copper foil must have a thickness of at least 35 micrometers, preferably approximately 70 micrometers, to ensure a sufficient distance between the platinum and the non-conductive plastic sheet, so that the danger of an electrical short circuit is reduced by the Welding paste Preferably, the non-conductive sheet is capton, which is sufficiently stable at the temperature for the DMS weld. Through . the narrow conductive paths, preferably approximately 0.4 millimeters wide, and thus, in accordance with the DMS standard, a clearly defined weld is possible. Advantageously, the conductor tracks extend parallel to each other and have a distance of their center lines preferably of approximately 1.27 millimeters, which also corresponds to the DMS standard. The conductive paths can extend parallel to the series of contact surfaces and also perpendicular thereto. However, in principle any address is possible. In an advantageous development of the invention, the conductive paths terminate at the edge of the carrier element, so that a visual inspection of the connection by welding is possible. In another embodiment, they present a restriction as a flow barrier, so that the soldier can only be carried out in a certain area and, in addition, a good union is ensured. In another embodiment of the invention, the conductor tracks are divided into two groups, which terminate at opposite edges of the carrier element. If the conductive pathways end at the edge of the carrier element, this may result in the absence of copper foil at the center of the carrier element. When electrically contacting the semiconductor chip disposed on the other side of the non-conductive substrate, with the contact surfaces by the ire-Bond technique, it can happen that the substrate sheet flexes, which can lead to poor bonding results. For this reason, in an advantageous development of the invention in the central area of the carrier element, surfaces of the copper foil are left, which are connected to the conductive tracks and / or to the contact surfaces, so as not to generate parasitic capacities. These surfaces act as support elements to prevent bending of the non-conductive sheet when joining by cable. In another embodiment of the invention, it is provided that the insulating sheet has at least one recess, which leaves exposed the connections provided for permanent contact (such as welding). It is thus possible to see the connections from the side of the insulating sheet, so that after a welding of the same, the result of the welding process can be optically revised. Without this notch according to the invention, an optical revision like this would not really be possible, since the electrically conductive sheet and the slots or recesses possibly present in the mass would be completely covered by the insulating sheet. Another development of the invention provides that at least one of the connections is flexed away from the insulating sheet. This has the advantage that, during the screed, a capillary effect of the weld is avoided in connections that only have a small distance, which can appear between non-bent connections, or flexed to move away. Another development of the invention provides that at least one of the connections is held on two sides of the recess, advantageously arranged opposite, in the insulating sheet. The fastening of the connection can be separated on one of the two sides of the recess, so that later this connection can also be moved away by flexing the insulating sheet. By fixing the connection on both sides, it is prevented from accidentally flexing or damaging due to handling or transport of the carrier element. On the other hand, by separating the fastening to the insulating sheet on one side, the bending away from the connection before a weld is still possible.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated below in more detail based on examples of embodiment, with the help of figures. Figure 1 is a perspective representation of the rear and front view of a carrier element in accordance with the invention. Figure 2 is a plan view of the carrier element according to Figure 1. Figure 3 is another variant of a carrier element according to the invention. Figure 4 is a carrier element according to the invention, on the side of the electrically conductive sheet. Figure 5 is the carrier element of the Figure 4, on the opposite side, in which the electrically insulating sheet is located. Figure 6 is a cross section of the carrier element of Figure 4, after a coated chip was affixed thereon and the connections flexed away from the insulating sheet. And Figure 7 is the carrier element of Figure 6 in a plan view.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows a carrier element in accordance with the invention, in a perspective presentation from the upper and lower side. In the right half of the drawing the upper side is shown, which has a non-conductive substrate 1 of a plastic as resistant to the possible temperature as, for example, capton-. A plastic housing 2 is arranged in the substrate 1, inside which is a semiconductor chip not shown. The plastic housing 2 can be placed by means of an injection mold or also by casting. In the latter case, a support framework can be foreseen on the substrate. In the left part of Figure 1 the lower side of the carrier element is shown, which has the contact surfaces 3, as well as the conductive tracks 4 joined in one piece with them. In Figure 2 this lower side is shown in a plan view. The contact surfaces 3 extend in two parallel series, along two opposite edges of the carrier element. Their surfaces cover the surfaces to be contacted by a reading device, whose size and position are defined by ISO 7816. Between the two series of contact surfaces 3, conductive tracks 4 extend, which are divided into two groups, each of the conductive paths 4 being connected with one of the contact surfaces 3. Both groups terminate at opposite edges of the carrier element, so that between the central lines of the conductor tracks 4, a distance of approximately 1.27 can be left. millimeters, to meet the standard for the DMS soldier. The conductive tracks 4 have, at least at their ends, where the weld takes place, a width of approximately 0.4 millimeters. In the carrier element shown in Figure 2, the conductor tracks 4 have a constant width. In this way, in the center of the carrier element and in the areas where the vertices of a semiconductor chip disposed on the opposite side of the carrier element rest, areas would result, where the copper foil would have been lost by corrosion. The problem then is that when the chip is connected by cable, that is to say, in its electrical connection with the contact surfaces, the non-conductive substrate can be flexed. For this reason, in an advantageous development of the invention, copper zones 5, 6, 7, 8, 9 were left, which are connected in one piece with some of the conductor tracks 4, to avoid parasitic capacities. However, in principle, the conductor tracks 4 can also be formed wider at their ends joined to the contact surfaces 3. The conductor tracks 4 have, near their free ends, stiffeners 10 which act as flow barriers for welding. In this way, even more precise screed can be carried out. The conductive tracks 4, in the modality according to the Figure 2, extend along the edge of the carrier element. But they could similarly end up in the center of the carrier element. NeverthelessIn this case, a visual inspection of the welding would no longer be possible. In Figure 3 another embodiment of a carrier element according to the invention is shown. The contact surfaces 11 also extend here in two parallel series, but along a central surface 12, which is formed in one piece with one of the angular contact surfaces ai. The composition of the central surface 12 and the angular contact surface Ia, has a groove 13, which is approximately as long as the width of the central surface 12. It extends parallel to the edge of the carrier element, at a distance approximately corresponding to the width of an adhesive sheet, with which the carrier element sticks to a plastic card. For this, a hot adhesion process is used, that is, a hot seal presses the carrier element for a certain time on the card, until the adhesive sheet has melted. The slot 13 prevents the heat of the seal on the copper foil from reaching the semiconductor chip, placed in the area of the surface 12, possibly damaging it. For the same reason, the central surface 12 does not reach the opposite edge of the carrier element. In contrast, one of the angular contact surfaces 11b at that location extends along the relevant edge of the carrier element. The conductive tracks 14 according to the invention, which serve for the welded DMS, extend in this embodiment perpendicularly to the direction of the series of contact surfaces and lie between the angular contact surfaces a ... , lid. For this reason, the central contact surfaces lie, ..., llh do not reach the edge of the carrier element, but only up to the line, indicated discontinuously, predetermined by ISO 7816. The minimum size and position of the surface of contactyoll is indicated by the area of dotted lines 15. The conductive tracks 14 are in this case considerably shorter than in the embodiment example of Figure 2, but still allow safe welding. Here, too, strictures can be envisaged as a flow barrier. However, the above is not shown in Figure 3. Also in the exemplary embodiment according to Figure 3, the width and distance of the conductive tracks comply with the DMS soldier standard. Figure 4 shows a development of the carrier element according to the invention, as already shown in Figure 3. Also in this case, the contact surfaces 11 are provided for a releasable contact of the carrier element and the connections 14 for a contact permanent of the carrier element. A releasable contact through the contact surfaces 11 occurs when the carrier element is used in a chip card, which can be inserted in reading apparatuses suitable for contact, and from which it can be removed again. A permanent contact is when the carrier element, instead of the above, is fixed, for example, on a platinum. In this embodiment, the carrier element has two recesses 17 in the insulating sheet 1, which make the connections 14 provided for permanent contact uncovered from the insulating sheet 1. Since the recesses 17 are located away from the outer edge of the insulating sheet 1, it is possible, as shown in FIG. 4, for the connections 14 to protrude from the recesses 17 and thus be fixed on two opposite sides of the recesses. 17, by gluing the insulating sheet 1. This fastening on two sides of the connections 14 has the advantage that, despite their filigranic dimensions, they are protected against damage. In this way, the stability of the carrier element is generally increased. Figure 5 shows the carrier element of Figure 4, from the other side. In Figure 5, the carrier element is already provided with a semiconductor chip surrounded by a coating. You can only see the coating 2 normally made of a duroplastic, and not the chip itself arranged inside. Also the electrical connections between the chip connections and the contact surfaces 11, or the connections 14, are covered by the coating of the chip 2. The fabrication of the carrier element can be carried out in the following manner: 1. For the manufacture of the electrically insulating sheet 1 is suitable, for example, an epoxy resin, a polyester or capton sheet. It has a thickness between 60 and 180 micrometers. By punching, perforations are made in the insulating sheet 1, through which the electrical connection between the chip and the contact surfaces 11, or the connections 14 can be subsequently generated. With this punching process it can also be carried out the recesses 17 in accordance with the invention. Fabrication of the electrically conductive sheets, advantageously copper, which has a thickness of 35 to 70 micrometers. Now, the contact surfaces 11 and the connections 14 can be made in the conductive sheet, either by punching, after which a joint lamination of both sheets comes, or before the structuring of the conductive sheet is carried out. joint lamination of both sheets, after which the structuring of the conductive sheet 4 is effected, by photolocal coating, a subsequent irradiation and corrosion. Coating of the conductive film with nickel (to obtain a diffusion barrier, an improvement of the binding capacity and increase the tribological properties) and with gold (to avoid corrosion and for optical reasons). Figure 6 shows the carrier element of Figures 4 and 5 in a cross section and Figure 7 in a plan view, the reproductions not being to scale. In the carrier element of Figure 6, the connections 14, for example by punching, were respectively separated on the side of the recesses 17 from their fastening with the. insulating sheet 1 and then flexed, or, layered downwards, away from the sheet 1. The electrical connection between the connections 14 and chip 18, of course, are maintained through the second attachment of the connections 14. The elbowing of the connections 14 has the advantage that a capillary effect for welding is avoided due to the relatively small distance between the adjoining connections 14. The vertical distance achieved by the bending distance according to the invention from the connections 14 between the welding surface and the underside of the insulating sheet 1 is decisive. In the figures, particularly in Figure 6, it can be observed clearly that by means of the recesses 17 according to the invention in the insulating sheet 1, when welding the connections 14 to obtain a permanent contact of the carrier element, there is, on the one hand, a direct access from above the insulating sheet 1 towards the point of soldier, and on the other, after finishing the soldier process, its result can be reviewed optically. The foregoing is particularly advantageous, since in the production of carrier elements, due to the mechanical stress due to the strong shrinkage of the coating material of the chip, it is possible to arrive at strong defects in the smoothness of the chip coating material of the electrically conductive sheet. This can produce short circuits between the contact surfaces 11 or the connections 14 or additional welding defects, such as insufficient humidification, plugs, etc. It is also possible, contrary to that shown in Figure 6, not to move away flexing the connections 14 of the insulating sheet 1, so that a punching of the connections 14 on one side of the recess 17 is not necessary. Although the advantage of avoiding a capillary effect for welding is avoided, manufacturing steps are saved maintaining the advantage of the possibility of visually checking the permanent contact and the secure attachment of the connections 14 to the insulating sheet 1. In other embodiments of the inventionIt is also possible for the recesses 17 to be arranged directly on the edge of the insulating sheet 1. In this case or when the connections 14 in the illustrated embodiments are not fastened to the outer sides of the recesses 17 (since they are not glued or not even protrude from the notch 17), it is possible in a particularly simple way to move the connections 14 away from the insulating sheet 1, since in this case a punching process is not required. Of course, embodiments of the invention are also possible, in which there are a er of recesses 17 in the illustrated carrier elements. By making a variation with respect to the illustrated objects, each of the recesses 17, for example, can be divided once more between each connection 14. According to the arrangement of the connections 14, an adjustment of the shape and the arrangement must be made. of the recesses 17. The invention is particularly suitable for permanent contact of the carrier element, through the connections, in DMS technology. However, it is also possible to introduce, in a conventional manner, the bending-away connections in perforations in a platiand to weld them there. Also in this case, the recesses according to the invention allow a visual inspection of the welding result. In order to obtain permanent contacts of the connections 14, in addition to welding, it is necessary to bond by means of a conductive glue. By forming according to the invention the contact side of a carrier element in plastic substrate, lined with metal, with conductive paths formed in one piece with the contact surfaces, the carrier elements can be incorporated in both chip cards and solder in plati

Claims (12)

NOVELTY OF THE INVENTION Having described the foregoing invention, it is considered a novelty, and therefore, the content of the following is claimed as property: CLAIMS

1. A carrier element for a semiconductor chip, in particular for incorporating in chip cards, in which a metal sheet is laminated on a non-conductive sheet and structured in such a way that two series of parallel contact surfaces are formed, which extend in the direction of opposite major edges of the carrier element, and the semiconductor chip is arranged on the side of the non-conductive sheet opposite the metal sheet, electrically connected to the contact surfaces, by recesses through the conductive sheet, characterized in that each of the contact surfaces is connected in one piece with a narrow conductive path in comparison with the dimension of a contact surface and that runs in a plane with it, forming connections, fulfilling the connections in their dimensions and distances each other with the ISO standard for DMS welds.

2. A carrier element according to claim 1, characterized in that the semiconductor chip is disposed in a recess of the non-conductive sheet, covered in its entirety by the metal sheet.

3. A carrier element in accordance with the one claimed in claim 1 or 2, characterized in that the conductive paths lead to the edge of the carrier element.

4. A carrier element according to claim 1 of claim 1, characterized in that the conductive paths respectively have a restriction. A carrier element according to claim 1, characterized in that the carrier paths are divided into two groups, the conductor paths of a group ending at opposite edges of the carrier element. 6. A carrier element according to claim 1 of claim 1, characterized in that the conductor paths end at the main edges of the carrier element. 7. Un. carrier element according to claim 1, characterized in that the conductor paths terminate at the edges of the carrier element which extend perpendicularly to the main edges. 8. A carrier element according to claim one of the preceding claims, characterized in that at least one of the conductive tracks has a conformation. 9. A carrier element according to claim 8, characterized in that at least one of the conformations is wider than the conductive tracks. 10. A carrier element according to claim 1, characterized in that the insulating sheet has at least one recess, which uncovers the parts of the connections provided for permanent contact. 11. A carrier element according to claim 10, characterized in that at least one of the connections is moved away by bending the insulating sheet. 12. A carrier element according to claim 10, characterized in that at least one of the connections is fixed on two sides of the recess to the insulating sheet.