Every time you tap your payment card, a tiny connection between the chip and antenna makes it all possible. This connection, invisible to the naked eye, must withstand thousands of flex cycles, temperature extremes, and years of daily use. The bonding technology used determines whether your card works reliably for its entire lifespan—or fails prematurely.
The Eight Main Bonding Technologies
1. Wire Bonding (Ultrasonic/Thermosonic Welding)
The industry standard for payment cards.
Ultra-thin gold or aluminum wires (typically 25-50 micrometers) connect chip pads to antenna terminals using ultrasonic vibration combined with heat and pressure. The process creates a molecular bond between the wire and contact surfaces.
Advantages: Proven reliability, mature technology, excellent electrical conductivity, well-established quality control processes.
Disadvantages: Wire loops add height, wires can break under extreme flex stress, requires careful encapsulation.
Used by: Most traditional card manufacturers including IDEMIA, Thales, G+D for standard dual-interface cards.
2. Flip Chip
The modern standard for thin cards and high-reliability applications.
The chip is mounted face-down with solder bumps or conductive adhesive directly connecting to the substrate. No wires needed—connections are made through tiny metal bumps on the chip itself.
Advantages: Reduced height (up to 50% thinner), superior flex resistance, shorter signal paths, up to 95% smaller footprint than wire-bonded packages.
Disadvantages: Higher equipment costs, requires precise alignment, more complex rework.
Used by: Premium card lines from all major manufacturers, metal cards, biometric cards.
3. Coil on Module (CoM) — Inductive Coupling
The next-generation contactless connection.
Developed primarily by Infineon, this technology eliminates physical wire connections entirely. A small antenna coil built into the chip module communicates with the card antenna through electromagnetic induction.
Advantages: No mechanical connection to fail, 30% thinner modules, simplified manufacturing, 5x faster production, compatible with eco-friendly card materials.
Disadvantages: Newer technology, requires specific chip designs, slightly higher initial component cost.
Used by: Infineon SECORA Pay solutions, adopted by forward-thinking card manufacturers.
4. Anisotropic Conductive Adhesive/Film (ACA/ACF)
Popular for RFID and high-volume production.
A special adhesive containing microscopic conductive spheres conducts electricity only in the vertical direction (Z-axis), preventing short circuits between adjacent connections.
Advantages: Simpler assembly, good for fine-pitch connections, no flux required, lower process temperatures.
Disadvantages: Lower mechanical strength than solder, can degrade in high humidity, less suitable for high-current applications.
Used by: RFID tag manufacturers, some transit card producers, TP-RFID, various Asian manufacturers.
5. TAB (Tape Automated Bonding)
Designed for mass production efficiency.
Chips are mounted on a flexible tape with pre-formed copper leads. The entire assembly is then bonded to the antenna in one operation.
Advantages: Very high throughput, consistent quality, good for automation.
Disadvantages: High tooling costs, less flexible for small batches, limited chip compatibility.
Used by: High-volume manufacturers in Asia, some SIM card producers.
6. Wire Soldering
A simpler alternative to ultrasonic bonding.
Similar to wire bonding but uses solder instead of ultrasonic welding to attach wires.
Advantages: Lower equipment costs, easier process control.
Disadvantages: Less reliable joints, thermal stress during soldering can affect chip, not suitable for finest pitches.
Used by: Some lower-cost card manufacturers, less common in premium payment cards.
7. Strap Assembly
Pre-manufactured module approach.
A complete chip module with connection straps is manufactured separately, then attached to the card antenna.
Advantages: Modular approach, tested before assembly, flexible card design.
Disadvantages: Additional assembly step, connection point can be vulnerability.
Used by: Various manufacturers for specific card designs.
8. Chip-on-Board (COB)
Direct chip mounting without traditional packaging.
The bare chip is mounted directly on the card substrate and wire-bonded, then protected with epoxy encapsulation.
Advantages: Compact design, cost-effective for simple applications.
Disadvantages: Chip exposed during manufacturing, requires careful handling.
Used by: Some contactless-only card applications, simpler smart card designs.
Reliability Comparison
| Technology | Flex Resistance | Temperature Range | Lifespan | Cost |
|---|---|---|---|---|
| Wire Bonding | Good | Excellent | 5-7 years | Medium |
| Flip Chip | Excellent | Excellent | 7-10 years | Higher |
| Coil on Module | Excellent | Excellent | 10+ years | Higher |
| ACA/ACF | Moderate | Good | 3-5 years | Lower |
| TAB | Good | Good | 5-7 years | Medium |
What Major Manufacturers Use
Infineon Technologies
Pioneered Coil on Module (CoM) technology with their SECORA Pay platform. Their modules are up to 50% thinner and 70% lighter than traditional solutions. The inductive coupling eliminates the most common failure point—the wire connection.
NXP Semiconductors
Offers chips optimized for both wire bonding and flip chip assembly. Their SmartMX series supports multiple bonding technologies depending on manufacturer preference.
Thales/Gemalto
Uses primarily wire bonding for standard cards with flip chip for premium and metal card lines. Their manufacturing facilities support both technologies with strict quality control.
IDEMIA
Employs wire bonding for mass production and flip chip for specialized products like biometric payment cards. Recently introduced bamboo-based eco-friendly cards using compatible bonding processes.
Giesecke+Devrient (G+D)
Utilizes advanced wire bonding with proprietary encapsulation for standard cards. Their premium lines use flip chip technology for improved durability.
The Critical Role of Encapsulation
Regardless of bonding technology, proper encapsulation is essential. After chip-to-antenna connection, the assembly is protected with:
- Epoxy Glob Top: A dome of epoxy resin covering the chip and wire bonds
- Dam and Fill: A barrier ring filled with protective compound
- Underfill: Epoxy injected under flip chips to distribute stress
Quality encapsulation protects against moisture, mechanical stress, and contamination. Poor encapsulation is a leading cause of premature card failure.
Why This Matters for Your Cards
When evaluating payment card quality, bonding technology directly affects:
- Daily Reliability: Will the card work consistently every time you tap?
- Flex Durability: Can it survive in a wallet, bent and flexed daily?
- Temperature Resistance: Will it work after being left in a hot car or cold winter?
- Lifespan: Will it last until the expiration date—or fail early?
Premium cards using flip chip or Coil on Module technology typically outlast cheaper alternatives by years. For organizations issuing payment cards, investing in superior bonding technology means fewer replacements, lower support costs, and better customer satisfaction.
The Future: Wireless Connections
The trend is clear: moving away from physical wire connections toward inductive coupling. Infineon's Coil on Module is leading this transition, offering cards that are thinner, more reliable, and easier to manufacture with eco-friendly materials. As this technology matures and costs decrease, expect it to become the new industry standard.