3 common process technologies for smart card milling and implanting

In the smart card milling and implanting industry, based on product characteristics and customer demands, the following three processes are generally adopted: hot melt adhesive process, conductive adhesive process and wire picking spot welding process, which are respectively applied in different scenarios.

In the smart card milling and implanting industry, based on product characteristics and customer demands, the following three processes are generally adopted: hot melt adhesive process, conductive adhesive process and wire picking spot welding process, which are respectively applied in different scenarios.

 

Hot melt adhesive process: Hot melt adhesive is a solid polymer at room temperature. When heated to a certain extent, it melts into a viscous liquid. It is applied to the connection area between the chip and the card base, pressed together, and then cooled to quickly solidify and complete the bonding. Its process is simple and easy to operate. It can be completed by using automated dispensing and hot pressing equipment, and has a high production efficiency. Hot melt adhesive has a relatively low cost, is non-toxic, odorless and solvent-free, and meets environmental protection requirements. However, hot melt adhesive has poor heat resistance. It may soften above 70℃ and is easily affected by chemical solvents. Smart cards are prone to counterfeiting and have poor security.

 

Conductive adhesive process: Conductive metal particles, such as silver powder, are added to the high-molecular resin adhesive. The conductive adhesive is placed at the connection point between the chip and the antenna through methods such as dispensing and screen printing. After curing at room temperature or by heating, a conductive path is formed. Due to the low curing temperature of the conductive adhesive, it can prevent components from being damaged by high temperatures and is suitable for temperature-sensitive components. By adjusting the formula, it can be adapted to different application scenarios and is also suitable for fine-pitch and miniaturized smart card packaging. However, when conductive adhesives are exposed to high temperatures for a long time, the resin is prone to decomposition, which may lead to phenomena such as silver migration, resulting in increased resistance and reduced reliability. Moreover, the electrical and thermal conductivity of conductive adhesives is usually not as good as that of metal welding.

 

The wire-picking spot welding process: First, a slot is mapped in the card base to expose the antenna. Then, the wire-picking mechanism is used to lift the end points of the antenna to position them appropriately for welding. Finally, heat is generated through discharge or combined with ultrasonic waves and pressure to fuse the antenna head with the chip pad to form a weld point. This process can achieve precise connection of extremely small-sized solder joints, with good electrical connection performance and low contact resistance. The process is mature. By optimizing the equipment parameters, the quality of the solder joints is stable and consistent. However, the process involves many steps, such as milling grooves, picking lines, and welding, which have high requirements for equipment precision and operation, and the overall cost is also higher.

 

The 3 types of technological processes each have their own advantages and disadvantages, and are also applied in different scenarios. Difference comparison.

In terms of connection performance, the wire spot welding has the best electrical and thermal conductivity, which can meet the requirements of high-frequency and high-speed transmission. Conductive adhesives come second, while hot melt adhesives are usually only used for insulating encapsulation and have basically no conductive ability.

In terms of reliability, the mechanical strength and long-term stability of the spot welding with wire picking are relatively high. Conductive adhesives are greatly affected by environmental temperature and humidity. Hot melt adhesives have relatively weak heat resistance and chemical resistance, which can easily cause problems with the card body packaging.

In terms of process complexity, hot melt adhesive has the simplest process, followed by conductive adhesive. It is necessary to control the curing conditions, and the most complex is line picking and spot welding, which has high requirements for the automation and precision control of equipment.

In terms of cost, the comprehensive cost of the hot melt adhesive process is relatively low, while the conductive adhesive has the highest process cost due to the slightly higher cost of conductive fillers and the large investment in wire picking and spot welding equipment.

 

Their specific application scenarios are:

Hot melt adhesive process: This process is low-cost and highly efficient, making it suitable for ordinary smart cards that do not have particularly high requirements for security and long-term reliability, such as simple access control cards and public transportation cards.

Conductive adhesive process: As smart cards are developing towards miniaturization and high precision, the demand for temperature-sensitive component packaging is increasing. Conductive adhesives can adapt to fine-pitch connections and their application in some high-end smart card and Internet of Things card fields is gradually increasing, especially the application of epoxy resin-based conductive adhesives is growing rapidly.

The wire-picking spot welding process: The wire-picking spot welding process features excellent electrical connection performance and strong reliability, and has certain applications in smart card packaging fields with strict performance requirements, such as financial payment cards, high-security government ID cards, and industrial-grade Internet of Things cards.