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card durability

Evaluating card durability

Employees in card issuing offices often have interesting stories of people coming in to replace their IDs. The card will be splitting into its different layers and when asked how it happened they explain they used it as an ice scraper on their windshield. Or the card will be warped and faded and the cardholder will admit to leaving it on their car’s dashboard on a hot summer day.

Federal and state agencies as well as other high-value issuers want to get as much out of a document as possible, and a 10-year lifespan seems the ultimate objective. To achieve this issuers are moving away from 100% PVC cards – the cheapest and most common type – to composite cards made up of a variety of materials, often including polyesters, polycarbonate or Teslin substrate.

Issuers are moving away from single substrate, monopolymer cards, says Joanne Ogden, global sales manager for the security division at ITW. “The standard is not a 100% PVC card anymore – because it’s not durable enough and won’t last five to 10 years,” she says.

In the past few years, the credentialing market has shifted dramatically when it comes to card materials, Ogden says. “The increased need for durability has completely changed the market. Gone are they days of PVC and top laminates,” she adds. “The documents now are far more complex, there are far more substrates out there along with an increased number of security features.”

Choosing the right materials for an identity card is important when it comes to durability. But the first thing an issuer must decide is what it means by durability. “What is the expectation of a document? Do they want it to last for five, seven or 10 years?” asks Pierre Scaglia, global segment manager for Secure Credentials at PPG Industries, which produces Teslin. “How will the document be used? Is it used once in awhile or several times each day? All of this will impact durability.”

The climate can even impact the durability of a credential. “Durability can depend heavily on the usage scenarios and environments,” says Brad McGoran, principal engineer at Exponent, a consultancy that performs card testing. “For example, cards used frequently outdoors can degrade and become brittle due to UV exposure, leading to premature failure and cracking.”

Security of the document also needs to be taken into account. An issuer can produce the longest lasting document, but if it doesn’t include security features strong enough to see it through such a lifespan, then it has done little good, Scaglia says.

Issuers are embedding security features into the different substrate layers of the card to make it counterfeit proof, Ogden says. “You might have a hologram embedded on one layer and another feature on the Teslin layer,” she explains.

Electronic components add another level of complexity when talking about durability. More and more, identity documents contain embedded electronics, and protecting these chips and antenna coils is important. “If you use highly rigid card materials with embedded electronics, in time they may crack,” says Scaglia. He adds that both PVC and polycarbonate are typically considered among the more rigid card materials.

Cards with embedded electronic components may have a shorter lifespan based on that fact alone, McGoran says. “With contact, contactless and dual-interface cards, our experience and testing have shown that the durability of the internal components, circuitry and connections can significantly affect card life longevity,” he explains.

Still, maximizing lifespan is the goal and composite cards made with different materials have the best durability, says McGoran. “Blended cards such as PVC and polyester blends tend to resist cracking during repetitive flexure testing better than pure PVC card stock,” he explains. “We have observed this often translates to longer service life in the field for these blended cards versus pure PVC card bodies.”

Blended cards such as PVC and polyester blends tend to resist cracking during repetitive flexure testing better than pure PVC card stock

Polycarbonate cards are popular for European credentialing projects, Ogden says. “But polycarbonate isn’t the only answer,” she explains. “There are other substrates out there that are more cost effective and could be used with both local and central issuance applications.”

“These alternatives can also be as or more secure and durable than all-polycarbonate cards because of their increased chemical resistance, abrasion resistance and flexibility,” says Scaglia.

Standardizing card durability

There are several facets to card durability. A primary consideration is the mechanical durability of the card body, which includes characteristics like bending and stiffness, peel strength and resistance to chemicals, says Brad McGoran, principal engineer at Exponent, a consultancy that performs card testing.

Additionally, there are the durability characteristics of the printed and laminated features on the card. These include the abrasion resistance of the magnetic stripe or printed barcode, the resistance of the printed dye to smear or drift, and the UV resistance of the printed surface, McGoran explains.

If the card includes an integrated circuit chip with a contact pad or a contactless antenna, durability issues also revolve around the resilience of those features. For example, the card should maintain functionality after exposure to x-rays and magnetic fields, and it should survive anticipated levels of electrostatic discharge exposure.

For each of these areas, internationally recognized standards bodies have developed a series of testing methods. Test labs implement these prescribed procedures to provide unbiased analysis of a specific card construction’s durability and likely longevity. Key test standards include ISO 24789 and ANSI 322.

ISO/IEC 24789: This standard is made up of two parts. The first is a methodology for determining a card’s expected lifespan taking into consideration the demands placed upon it by the various applications it will support. The second part uses this determination to define a series of tests to evaluate if it can meet this prescribed lifespan.

Think of it this way, the demands on a passport card used infrequently for international travel are far less than those placed on a fare collection card used multiple times each day for public transport. Still the required lifespan for a passport card is far longer than that of a transit card, so this too must be taken into consideration as tests are designed.

ANSI INCITS 322: This defines a Card Structural Integrity Test to help gauge a card’s resilience against delamination under adverse environmental conditions. The test is considered rigorous or extreme, and used most often as a qualitative or comparative assessment between different card constructions.

To conduct one of the ANSI INCITS 322 tests, cards are placed into a one-gallon paint can along with “dummy cards.” Thirty-milliliters of distilled water and 10 grams of sand are added, and the can is sealed and mounted into a standard paint shaker similar to the machines used at hardware stores. The cards are then shaken for three hours, removed and rinsed. The cards are generally considered satisfactory if they do not delaminate or peel apart. If they include an integrated circuit chip, this should still be functional.

This test has proven to be quite revealing for the various card materials and structure technologies used by card manufacturers. Many cards come out of the shaker with only worn corners, but some cards simply disintegrate or separate into their component layers.

ANSI INCITS 322 Surface Abrasion Test

To conduct the Surface Abrasion Test, two cards are mounted on a machine that rotates them below a pair of abrading wheels or grinders of prescribed weight and grit rating. The machine is stopped every 250 rotations and a resurfacing disk with a prescribed grit rating is used to resurface the abrasion wheels. After every 500 cycles the cards are photo documented. This process continues until the cards reach 5,000 cycles. The estimated point of print breakthrough is tracked and recorded.

A card issuer caveat emptor

When it comes right down to it an issuer has to look at the use of the credential. “In our experience, there is no one single formula for the best and most durable card body construction since different blends and formulations are best suited to different environments and usage scenarios,” McGoran says. “We recommend that issuers and their card manufacturers run specific tests to evaluate overall durability of the card body to ensure that fielded cards meet their designated life expectation.”

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