Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1999-10-04
2002-06-11
Gandhi, Jayprakash N. (Department: 2841)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S736000, C361S764000, C361S765000, C257S679000
Reexamination Certificate
active
06404643
ABSTRACT:
The present invention relates to an article, and, in particular, to an article having an embedded electronic device and a method for making the article.
The plastic “credit card” has seemingly become ubiquitous. Not only are plastic cards in use worldwide for purchasing goods and services, whether through credit or debit type accounts, but they are rapidly coming into use for many other uses, such as membership cards, library cards, identification cards, access cards, driver's licenses and the like. With the increasing use of plastic cards has come the increasing misuse thereof, whether by thieves or persons seeking unauthorized access or a false identification.
The first innovation to make these ubiquitous plastic cards easier to use and more secure against misuse was the addition of a stripe of magnetic material in which can be encoded information facilitating the use of the cards, such as account numbers and expiration dates, as well as security information, such as personal identifying information and PIN numbers. The magnetic stripe has the advantage of being easy and inexpensive to manufacture and encode. The proliferation of these cards is aided by an International Standardizing Organization (ISO) standard for the dimensions and stripe properties for such cards. Thereafter followed the addition of an embossed “holographic” or diffraction grating optical patch that changed color and/or design as viewed from different angles onto the cards. These optical devices had the advantage that they were very inexpensive to manufacture, but the manufacturer needed sophisticated and expensive machinery to do so, thereby making counterfeiting impractical.
Alas, the ingenuity of the thieves and counterfeiters has enabled them to also reproduce magnetic stripe plastic cards and even embossed optical patch security features. To achieve greater security, a more sophisticated information repository was needed that is also more difficult to counterfeit, or at least one that is more expensive and requires sophisticated production machinery. The embedded electronic device, in particular the semiconductor chip, has provided the best solution thus far. Such electronic devices may include a memory device, a microprocessor, or a combination thereof, and are conventionally embedded in a cavity formed in a plastic card blank. Electrical signals are coupled into and out of such embedded electronic devices either by direct electrical contact to contact pads on the plastic card in the case of “direct contact type” cards or tags, or by radio-frequency (rf) signaling between a card reader and a receiver/transmitter antenna embedded in the card in the case of “contact-less type” smart cards or tags. A plastic card including one or more embedded electronic devices is often referred to as a “smart card.”
Conventionally, smart cards are commonly made of rigid polyvinyl chloride (PVC), however, PVC is gradually being replaced by polyester thermoplastic (PET) resin. The properties of these thermoplastic resins, particularly the melting temperature, dictate for the most part which of the available manufacturing processing techniques have suitable temperature and time exposures and so may be employed. PVC resin typically softens and deforms at a temperature around 60-80° C., depending on the amount of plasticiser used in the processing of the PVC card substrate. Typically, the electronic device is mounted to and is electrically connected to one side of a small printed wiring electronic substrate by wire-bonding connections using very fine gold or aluminum wires. This small substrate is necessary because the bonding of the gold wires must be performed at a temperature of 150-250° C. which is higher than the thermoplastic card substrates can withstand. After wire-bonding the input/output connections of the electronic device to the electronic substrate with gold or aluminum wires, the electronic device is then encapsulated to the electronic substrate with a glob of resin for both mechanical and environmental protection. This intermediate electronic substrate with an electronic device wire-bonded thereto forms a module that is subsequently bonded onto a cavity machined or otherwise formed in the card substrate, which bonding is performed at a temperature around 60° C.
FIG. 1
is a cross-sectional side view of a prior art smart card
100
of this type. Plastic card blank or substrate
102
has a cavity
104
formed therein. An electronic module
110
includes an electronic device
112
attached to one side of an electronic substrate
114
, which may be of type FR4 printed circuit board material, for example. Conventional conductive epoxy that cures at a temperature of about 150° C. attaches electronic device die
112
to substrate
114
. Input/output connections from electronic device
112
are connected by bond wires
116
to contact pads on electronic substrate
114
which connect to external contacts
118
on the other side thereof. Electronic device
112
is encapsulated to electronic substrate
114
by encapsulant
118
which may be either dispensed thereon or molded thereto, typically at a temperature of about 150° C. A quantity of adhesive is dispensed into cavity
104
of card substrate
102
and then module
110
is inserted therein to complete smart card
100
. One problem associated with this method of assembly is the need to precisely control the dispensing of both encapsulant
120
and adhesive
106
so that the external surface of substrate
114
when fully inserted into cavity
104
is substantially co-planar with the one surface of card substrate
102
. In practice, this is difficult to achieve. In fact, the top of cured encapsulant
120
is typically ground off to obtain the controlled thickness and parallel surface necessary for proper assembly into a card. Another disadvantage results from the individual handling and multiple wire bonds required for each electronic device, and from the separate individual glob-type encapsulation process. Each of these operations increases the cost of conventional smart card
100
, so that the cost of each card can be as high as $0.50-$1.00 U.S. per card when purchased by the customer. Little improvement is possible with conventional methods, except possibly by using adhesives that bond and cure faster to reduce the process time required to attach module
110
to card substrate
102
. Current production adhesives typically cure at a relatively low temperature, e.g., less than 60° C. for a reasonable time, e.g., 30 minutes or longer.
Similar processes of wire bonding and assembling of electronic devices into a smart card are employed for card substrates formed of PET resin. The properties of PET resin differ from those of PVC primarily in the higher softening and deformation temperatures of PET of about 110-130° C. With PET resin card substrates, the electronic device module attachment may be performed at slightly higher temperature, for example, around 120° C. without causing a major problem. This opens up additional possible uses of smart cards in higher temperature environments, if smart cards having appropriate properties are available, but with the same problems and disadvantages as set forth above for PVC cards.
Direct-contact type smart cards are also limited by the number of contacts that are available between the smart card and the card reader, as well as the durability and reliability limitations of electromechanical contacts. A long-term solution that avoids these limitations of smart card utilizes wireless communication methods to communicate with a contact-less smart card. Because the card need not be in physical contact with the card reader, but only need be “near” the reader, a contact-less smart card is particularly suited important for fare and toll collection, access control, time-attendance, and other conventional smart card applications. The characteristics of the particular RF wireless communication link between the smart card and the card reader determine what is “near” in a particular application, whether that be a matter or inches, fee
Amerasia International Technology Inc.
Dann Dorfman Herrell & Skillman P.C.
Dinh Tuan
Gandhi Jayprakash N.
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