Metal working – Barrier layer or semiconductor device making
Patent
1994-04-05
1997-10-28
Graybill, David E.
Metal working
Barrier layer or semiconductor device making
437214, 2643287, 26427217, H01L 2156, H01L 2158, H01L 2168
Patent
active
056813562
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method and apparatus for producing chip cards and chip card blanks whose wall thickness is reduced in certain areas by injecting a molten plastic material into a mold space and then cooling the plastic material.
EP 0 277 854 A1 and EP 0 267 826 A1 disclose chip cards or chip card blanks having a membrane area or depression for taking up the chip module and made by injection molding.
In the card production method presented in EP 0 277 854 A1 the module is already located in the casting mold during the injection process, being held there by suction air. A plate spring-mounted in the cavity of the casting mold for pressing the module against the upper casting mold ensures an additional positioning and fixation of the module prior to injection molding. The plastic is injected via a side edge of the mold whereby the plate is lowered to card thickness due to the arising pressure.
This method permits production of a chip card in one operation. Since the module is located in the mold space during the injection process, however, it acts like a die protruding into the casting mold. Due to the lateral injection of the material the plastic stream divides into two streams before the module or before a die, flowing around the obstacle and reuniting behind it. This gives rise to a preferred molecular orientation in the direction of flow behind the obstacle in the mold space, which might result in predetermined breaking points. Furthermore the direction of flow defined by the lateral injection channel does not permit the formation of complex, sharp contours in the area of the membrane as are necessary for example for forming anchoring elements for the module. Finally voids can form due to inclusions of air in the membrane area upon lateral injection.
EP 0 267 826 A1 presents a method for producing chip card blanks by injection molding. The casting mold used is formed from plane-parallel plates that are mutually movable. The injection channel is provided in one of the plates. Disposed opposite in the other plate is a die protruding into the casting mold and provided with cooling ducts to mold the recess for taking up the chip module in the card later. The die has depressions on its face to produce knobs in the bottom of the module recess. When the chip module is introduced into the recess it lies on the knobs so that the gap between the chip module and the bottom can be filled with an adhesive for fastening the module.
The method presented in EP 0 267 826 A1 eliminates the disadvantages of the method stated in EP 0 277 254 A1 due to the position of the injection channel. In particular, no preferred break points arise and complex, sharp contours (knobs) can be formed in the area of the face of the die. Due to the position of the injection channel, however, the inevitable injection nipple is located in the area of the membrane on the back of the card blank, which impairs the visual appearance of the finished card. An even more serious problem is that the plastic material is first injected into the area with reduced wall thickness and then flows into the other areas with a considerable pressure loss. There is therefore a danger of the peripheral areas of the mold space being incompletely filled with plastic material.
Summing up it can be said that both methods permit inexpensive production of chip cards or chip card blanks but involve quality losses.
The present invention is thus based on the problem of providing a method and apparatus of the above species to permit economical production of chip cards and chip card blanks whose wall thickness is considerably reduced in certain areas, without the described restrictions.
This problem is solved according to the invention by the features stated in the characterizing part of the main claim.
In the inventive method the plastic material is thus first injected into an initial mold space whose configuration corresponds substantially to that of the molding without any reduced wall thickness. Since there are no reductions of area obstructing the flow p
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Baader Helmut
Barak Renee-Lucia
Haghiri-Tehrani Yahya
GAO Gesellschaft fur Automation und Organisation mbH
Graybill David E.
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