Registers – Records
Reexamination Certificate
1999-03-04
2001-05-01
Frech, Karl D. (Department: 2876)
Registers
Records
C235S492000, C361S737000
Reexamination Certificate
active
06223989
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement to a method for making smart cards, of the type having a card body and an electronic module, and cards obtained by implementing the method.
2. Description of the Related Art
Of the existing methods, a method is known of furnishing a card body with a cavity, an electronic module having principally contact pads and a semiconductor chip containing an integrated circuit, and of securing the electronic module in the cavity with gluing means such as a cyanoacrylate glue. In general, the gluing operation is divided into a prior operation in which the module is inserted into the cavity, and a pressing operation of a predetermined length.
However, practical implementation of such a method, usually called “encartage” in French, on an automated industrial scale, which requires separate sequenced operations carried out at different stations, and transferring cards from one station to the next at high speed, on the order of several thousand cards an hour, leads to several problems affecting the quality of the finished product.
In particular, the inventor has found that the cards obtained by gluing using the operations listed above often have major drawbacks.
The principal drawback is incorrect centering of the module in the cavity. Despite correctly centered insertion of the module in the cavity, the inventor found that after gluing some modules were off-center, i.e. had shifted from their initial insertion position. Typically, incorrect centering was slight rotation, or translation, or both at the same time inside the cavity, or in extreme cases outside the cavity with the contact pads having one edge overlapping the surface of the card body.
The inventor found that the incorrect centering resulted in particular from forces produced on the card while it was being moved from one station to another, particularly sudden acceleration or deceleration forces brought about by the card leaving the insertion station and stopping at the pressing station, respectively.
Incorrect centering can also result from residual constraints present in the module which tend to produce a slight inward curvature. In this case, there is a risk of the module popping out of the cavity with each acceleration or deceleration referred to above.
Defects relating to poor adhesion of the module to the card body have also been found. In these situations, the card cannot meet the mechanical strength criteria imposed by current standards (ISO and AFNOR) for bending, twisting, and separating forces.
SUMMARY OF THE INVENTION
It is accordingly necessary to solve these problems without decreasing production rates.
The present invention relates to an improvement to the method of gluing an electronic module into a card body that can be compatible with automated very-high-speed industrial production without thereby generating defects involving module centering or adhesion.
For this purpose, the present invention relates to a method for making electronic module cards of the type in which a card body with a cavity is provided with an electronic module whose dimensions match the cavity, and at least a first gluing means is adherable to the card body and to the module, including the steps wherein at least the first gluing means is deposited in the cavity, the module is inserted into the cavity in a substantially centered position, and at least the first gluing means is pressed between the card and the module.
The method is characterized in that it additionally has a step of providing a second gluing means which is also deposited in the cavity, the second gluing means being able to exhibit gluing properties that are sufficient to keep the module centered in the cavity at least until the first gluing means is pressed.
Because of the use of this second gluing means with gluing properties (adhesion and high viscosity), the cards can be subjected to any acceleration or deceleration during manufacture without incorrect centering* being affected thereby.
In addition, it is possible significantly to decrease the time taken by inserting the module and hence to increase production speeds.
The invention also enables the first gluing means to be selected and used under optimum conditions so that it can better withstand module separating forces and bending/twisting forces.
According to one advantageous embodiment of the method, the second gluing means is selected from materials able, after processing, to withstand separating and/or bending/twisting forces and the material is used in a way that withstands such forces.
Thus, the second gluing means, when properly treated, has the additional function of contributing, with the first gluing means, to withstanding the separation and/or bending/twisting forces imposed by the current standards referred to above.
According to one preferred embodiment, a light-curable epoxy resin is used. This resin can be subjected to ultraviolet radiation prior to insertion of the module if it is also intended eventually to fulfill a mechanical strength function thus contributing to the mechanical strength of the card body plus module.
Because of this method of implementation, activation of the dot of the second gluing means can be favored effectively and independently of environmental operating conditions. In addition, it is easy to change the kinetics of the resin polymerization reaction by changing the intensity and exposure time of the resin to the ultraviolet radiation.
According to another characteristic that gives good module holding results, the resin has a viscosity of 50,000 m.P/second.
According to another characteristic that gives good results and for reasons of convenience in implementing the method, a drop of 0.003 gram is deposited in the center of the cavity, and the resin is exposed to radiation so that its open time is approximately 60 seconds.
According to a second embodiment of the method, a cyanoacrylate glue gel is used under appropriate temperature and relative humidity conditions before inserting the module.
The use of this gel is advantageous because the gel can be used under economical conditions.
According to another characteristic of gel use with good module-holding results, a drop is deposited in the center of the cavity under temperature and relative humidity conditions that allow an open time of approximately 60 seconds.
According to another characteristic of the method, according to the first or second embodiment, the method may use a cyanoacrylate type glue as the first gluing means.
This glue has the advantage of being convenient and economical to use.
This first gluing means can be deposited in a quantity such that, after pressing, a gluing area of between 50 and 100% of the area of the cavity is covered, in the form of at least four lateral glue dots in the location of the contact pads at a temperature of 18 to 24° C. and a relative humidity of between 60 and 75%.
Such operating conditions allow high-speed industrial production with few defects, the first gluing means being a cyanoacrylate glue.
According to another preferred characteristic of the method, cyanoacrylate glue is deposited just before the insertion step.
In this way, better results are achieved in terms of cyanoacrylate glue adhesion to the module.
According to another characteristic of the method, the cyanoacrylate glue chosen is preferably relatively pure, the open time of the cyanoacrylate glue being approximately 60 seconds under the above operating conditions.
Thus, this glue provides better adhesion because it polymerizes relatively slowly.
The present invention also relates to an electronic module card obtained according to the above method.
Other characteristics and advantages of the invention will emerge more clearly by reading the description hereinbelow of two principal embodiments provided solely as examples. It should be read with reference to the attached drawings wherein:
REFERENCES:
patent: 4871405 (1989-10-01), Denda
patent: 4903118 (1990-02-01), Iwade
patent: 5169056 (1992-12-01), Reele
patent: 5612532
Cyr Daniel St.
Frech Karl D.
Gemplus S.C.A.
Plottel Roland
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