Registers – Records – Fluorescent – phosphorescent – radiation emitting
Reexamination Certificate
1997-09-26
2001-04-03
Frech, Karl D. (Department: 2876)
Registers
Records
Fluorescent, phosphorescent, radiation emitting
C235S492000, C235S487000, C029S826000, C257S679000, C438S123000
Reexamination Certificate
active
06209790
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a data medium in card form which is produced substantially from plastic, may have metal parts, comprises a large semiconductor memory capacity and, for data transmission, can be externally bonded via electroplated contacts.
An example of data medium systems currently known and in use is that of magnetic tapes, which generally consist of polyester and are covered with a magnetic powder or a magnetizable layer. Many forms which this takes may be mentioned, such as tapes, cassettes, cartridges or else that of the smart card, which consists, for example, of PVC (polyvinylchloride) and may have an impressed structure or a magnetic strip. Furthermore, optical systems are known, such as CD (compact disc; CD-ROM/compact disc; read-only memory). The individual forms may be only readable or readable and also rewritable.
The latest data medium systems comprise one or more semiconductor memory elements. Suitable for this, in particular also for reasons of cost, are commercial random-access memories. These may be designed, for example, as a DRAM (dynamic random-access memory). Today, the most popular type of data medium system, in particular data medium card, is the smart card. Also known are data media for data processing systems (PCMCIA standard), which can be used, for example, on a personal computer for backup as external data media. These comprise a multiplicity of semiconductor elements and may also serve, for example, as a substitute for a hard disc.
In the case of the so-called smart card, in a version as a chip card, and in the case of a memory card, the contact-dependent data transmission is generally performed using electroplated contacts. This constitutes a fundamental difference in comparison with an electronic standard component. A DIL (dual in line) package of a semiconductor chip has entirely different external bonding means than one of the cards mentioned. In the case of a data medium in card form of the abovementioned type, plug contacts are generally used, specially designed according to type and requirements. Firstly, the semiconductor memory elements have to be integrated into the plastic cards, these cards not necessarily having to conform in their dimensions to a standard for chip cards, although it is advisable for them to do so. What is essential is that the required memory capacity of the semiconductor elements in a data medium card is combined with an essential space requirement for such semiconductor memory chips. The data medium systems in the form of a data medium card have, as stated, so-called plug and pull contacts and must correspondingly transfer forces in order that the card can be plugged into or pulled out with the corresponding contacts on a data processing system or on an adapter. Since the relatively large main faces of such a data medium card are to serve essentially for imparting advertising information, it would be important to make the electroplated contacts intrinsically stable, in order not to cause damage to the advertising areas by a transfer of force to the plastic body of the data medium. This must also be seen against the background that, in use, such a card is to withstand as far as possible without any damage a very high number of insertion and removal operations.
Examples of special configurations of electroplated contact connections which may be mentioned at this stage are plug and pull contacts or snap connections, multipoint connectors and terminal strips or the like.
It is evident that the external electrical connection of a semiconductor device takes place in any case via a disconnectable electrical connection. In contrast to this, the standard assembly process of a semiconductor device in conjunction with a leadframe provides a non-disconnectable electrical and mechanical connection of the outer leads. The assembly technique in the case of a chip card cannot be transferred to a data medium of the type described above in as far as the module inserted into a chip card is very small in relation to the size of the data medium card.
SUMMARY OF THE INVENTION
The invention is based on the object of providing a data medium in card form which has one or more semiconductor memory elements with a substantial space requirement within the card, for data transmission is provided externally with electroplated contacts and, during operation, has overall high stability, with respect to the plastic body and the contacts. Also to be provided is a leadframe which is designed for use in such a data medium in card form, with the corresponding requirements, and which significantly simplifies the production process of the data medium.
The invention is based on the realization that special advantages are associated with a leadframe which is of an integral or one-piece design with the electroplated contacts or with parts thereof. This means that the leadframe serves on the one hand for the electrical bonding and mechanical securement of the semiconductor memory element or elements and on the other hand for the forming of the electroplated contacts. No conventional leadframe material can be used for this purpose. In order to meet the requirements, on the one hand concerning semiconductor memory elements and on the other hand concerning electroplated contacts, a compromise has to be made in the case of the material used.
In an advantageous way, a special resilient material is used, which has such material characteristics that it simultaneously meets requirements on the chip bonding, and also the requirements on the electroplated contacts. With respect to the requirements, it should be mentioned in particular that the temperature coefficient of the modulus of elasticity (temperature dependence, also referred to as temperature sensitivity) is very low. At the same time, the coefficient of thermal expansion is likewise to be low, in order that a good adaptation of the metallic leadframe, which bears semiconductor elements, to the material of a semiconductor element is ensured. Furthermore, a high or very high resilient bending limit is desired. It is also not to drop significantly even at relatively high temperatures.
A special resilient material with the said requirements consequently meets on the one hand the requirements which are imposed on electrical conductor paths and on the leadframes, together with the requirements which are imposed on, for example, resilient electroplated contacts. Points to bear in mind overall in this respect are the chip fixing, the chip positioning on an island of a leadframe, the electrical current carrying, and also the external bonding and the resilient properties of contacts, such as they are desired from precision engineering. Consequently, the electrical conductor or conductors are of an integral or one-piece design with the external contacts of a data medium in card form.
To be mentioned as a special material selection are the alloys copper-tin-6 and copper-tin-8 (CuSn6, CuSn8). These are particularly favourable combined leadframe materials with resilient properties. Desirable in this context is, for example, a yield strength of over 1000 N/mm
2
. This value can be achieved, for example, by iron-nickel alloys. In order to reduce the corrosion susceptibility of iron alloys, they are alloyed with chromium fractions. For example, the use of an alloy such as iron
ickel/42/chromium/5 (FeNi42Cr5) is advantageous. This alloy meets the abovementioned requirements and likewise has corrosion protection, so that there is no need for coating the leadframe with a layer of noble metal. The chromium fraction brings about a self-passivation. By further metallurgical or metallographic adjustments, such as for example high purity of the material or low particle size, a positive influence can be brought to bear on, for example, the electrical conductivity.
The previous use of leadframes in the production of plastic-encapsulated electronic components envisages the mechanical securement of the electronic components on an island of the leadframe, the electrical bonding between the electroni
Filser Christoph
Houdeau Detlef
Kirschbauer Josef
Cyr Daniel St.
Frech Karl D.
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
LandOfFree
Data medium in card form and lead frame for use in such a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Data medium in card form and lead frame for use in such a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Data medium in card form and lead frame for use in such a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2450682