Smart System for Moulding Smartcards

Semiconductors surround us, and more are coming. Cars that talk and appliances that remember how you like things done are only the tip of the silicon iceberg. Putting the chips where they need to be--in the hands of users--is a crucial hurdle in bringing this technology to market.

The chip card or smartcard--basically a plastic card with a memory or processor chip--is one of the more promising vehicles. Already used in telephone cards and other applications, the day is drawing near when you may start a trip by putting your life's medical history into your wallet . . . pay the highway tolls on the way to the airport without stopping or even slowing down . . . enter a secured parking area . . . take a snack from a vending machine . . . and even board an airplane without cash, but with a smartcard.

For chip cards to enter the hundreds, and more likely thousands, of potential applications requires a highly productive, highly flexible manufacturing system. A chip card maker needs to handle small production batches, different decorations, and different chips, efficiently and profitably. In a magazine about injection moulding, why discuss cards made by printing and cutting extruded plastic sheet? Well, card production technology is moving forward. By joining state-of-the-art injection moulding, semiconductor packaging technology, and robotics, Sempac SA of Cham, Switzerland has created a productive, yet flexible, smartcard production system. IMI went to see it.

Printing Only One Component

Credit card production is based on the printing business: print on a plastic sheet, apply the magnetic strip, and cut out the cards. Chip cards started in France with government backing, and initial production logically went to the printers making credit cards. They merely added the process of gluing on the chip. With no insult to adhesive technology, "gluing" a chip to a card that contains sensitive personal data or grants entry to a restricted area has some obvious security drawbacks. Perhaps an even larger problem results from the separation of semiconductor technology and card manufacturing. The card producer has little or no control of semiconductor production schedules and costs.

Sempac's idea for integrating card manufacturing and semiconductor packaging began as an airplane conversation between two executives of Esec, a worldwide supplier of semiconductor and circuit board production systems. They in turn convinced management, and Sempac was born as a unit of Esec. One of those executives, Willi Truckenbrod, is now in charge of Sempac's marketing and sales. He says the next, and most critical, move was creating the team needed to make the system a reality. Esec combined its semiconductor production knowledge with DSM's polymer know-how (ABS in particular), Netstal's injection machinery, and moulds from AWM Werkzeugbau.

Readying a Chip

The Sempac process, which consists of four machines, begins by picking the semiconductor chips from a production wafer and die bonding them to a metal leadframe. The actual manufacture of the chips is not in the equation due to the highly specialized and capital intensive technology required. The leadframes are a standard in semiconductor manufacturing. Besides simplifying handling, they provide a standard carrier for any size chip up to 4 by 6 mm. Switching from memory chips to larger microprocessors is simple, and requires no downstream modification.

In the second station, the wire bonder makes the low-loop, gold wire connections between the chip and the leadframe. Though normal processing temperature is 250 C, the leadframe remains stable. Gold wire bonding is four times faster than other methods and the low height of the loops (150 micrometers) is a significant contributor to the thin (.7 mm) profile of the finished chip cards.

The third station uses multiplunger technology to simultaneously encapsulate 16 chips in a leadframe. Four plunger units simultaneously encapsulate four chips each. Regardless of the size of the chip inside, the ISO standard tool used here creates the same size. The material is not a multicomponent epoxy, and doesn't require knowledge of that material's handling and mixing. The fourth machine is a highly integrated injection moulding-based production cell.

Moulding Production Cell

The 16-chip leadframes are stacked in a cartridge and loaded into the injection moulding cell. Before moulding, the chips are trimmed and shaped to avoid movement inside the mould during injection. This forming also assures that the chip is integral to the finished card and virtually impossible to remove without destroying the card. The chip is tested inline and only good units are pulled from the leadframe to be moulded. The front and back of the card consist of preprinted ABS labels loaded in cartridges and inserted into the mould in a completely automated in-mould labeling (IML) operation. A custom-designed high-speed, side-entry robot positions the labels and the chip modules into the mould's four cavities simultaneously.

Since both label magazines and leadframe cartridges are easily and quickly changed, product changeover is fast. Hot runners support the fast changeover, plus minimize material consumption. Cards are taken from the mould by the robot. Small edge gates are cut from between the card pairs for recycling, and after that the cards are handled individually. A cleaning station for contacts precedes an in-line functional testing station. Depending on the type of chip, the test cycle can exceed the 9-second cycle time, in which case testing can go offline. There is space for such additional inline functions as adding a magnetic strip or additional printing. Finally, the cards are stacked in containers ready to be loaded or programmed.

Specific Material and Machine Technology

Each of Sempac's development partners for the Compact Line has put years of effort into the project. DSM Performance Polymers, which developed a grade of ABS specifically for this application, says combining well-above-average flow with high-performance mechanical properties was a special challenge. The material used is a reactor-grade ABS supplied as beads to reduce dust. Despite an MFI of 50, it withstands a flex-torsion test that severely bends the card 1,000 times in each direction. That test will likely be increased to 4,000 times. DSM also has specific ABS grades for a variety of other cards, including cellular telephones and chip cards produced by different systems. Among other features, it has eliminated the problems caused by surface grease on cards that need to be printed.

Netstal says its 90-ton machine in the Sempac line corresponds to its SynErgy 900/110, but is absolutely dedicated to this application. Sempac says the basic precision of the machine was a strong point in its selection. Netstal attributes this not only to the machine's Sycap closed loop process control, but also to its basic robustness, rigid platens, solid tiebars, and mould plate support and guidance system. The ability to completely incorporate all the production cell's functions into the closed loop control system was also critical.

Netstal paid particular attention to fast startup because of frequent product changes. The benefit to the card maker is zero-defect quality from the first shot. For long service life, the injection unit has a bimetallic cylinder and a hardened 25-20 D plasticizing screw. The machine's layout is adapted to the preparation and handling machinery integrated into the cell, in particular to permit good accessibility to the various subsystems.

Sempac is not the only solution available for chip card production, but its degree of integration provides a card maker all the advantages of a turnkey system, including control of the scheduling and costs of semiconductor packaging. The productivity rate is around 2,000 cards per hour, and the cycle time is being reduced. So far, eight systems have been installed with more on order.

Market penetration is faster where there is no established infrastructure to be displaced. Two of the systems are making telephone cards in Poland. Others are at work in Latin America. Ultimately, however, it is the multitude of potential applications and the chip card's user benefits that will make this market grow. One forecast solely for contactless cards--they can be scanned while still in your pocket and the security door opens--predicts 1.2 billion cards being made in 1999. The applications will surely multiply as people become aware of the technology. An African nation, for example, wants to use the cards to control the distribution of water.--Robert Neilley

Contact Information
Sempac SA
Mr. Willi Truckenbrod, VP Marketing & Sales
Hinterbergstr. 9
CH-6330 Cham
Switzerland
Tel: +41 (41) 749 53 53
Fax: +41 (41) 741 61 24

DSM Performance Polymers
Mr. Chris Borgmans
P.O. Box 43
N-6130 AA Sittard
The Netherlands
Tel: +31 (46) 477 3323
Fax: +31 (46) 477 3405

Netstal-Maschinen AG
Mr. Thomas Landolt, Marketing Manager
CH-8752 Nafels
Switzerland
Tel: +41 (55) 618 6111
Fax: +41 (55) 612 3541