Advanced wafer level packaging technology empowers TWS headphone industry upgrade

1、 Project Background

With the rapid development of the TWS headphone market, consumers have increasingly high demands for products that are lightweight, have long battery life, high sound quality, and low latency. As the core component of TWS earphones, the packaging technology of the Bluetooth controller chip directly determines the overall performance and user experience of the product. The traditional QFN packaging technology is unable to meet the design requirements of the new generation TWS earphones due to issues such as large packaging thickness, limited electrical performance, high material costs, and long production cycles. To address these industry pain points, we have launched an advanced wafer level packaging solution based on FOWLP and WLCSP dual technology routes, which has been successfully applied to the mass production project of a well-known brand TWS earphone Bluetooth master chip.

2、 Core solution

The core of this project adopts a dual technology route of fan out wafer level packaging (FOWLP) and wafer level chip size packaging (WLCSP), which can provide flexible packaging options according to different product needs of customers. FOWLP technology is particularly suitable for multi chip heterogeneous integration scenarios, enabling the integration of more functions without increasing packaging size; WLCSP technology is suitable for single-chip packaging and has the advantages of simple process and lower cost.

The core process foundation of the solution is high-precision rewiring layer (RDL) technology, which directly realizes the interconnection between chips through RDL, replacing the lead frame and carrier board in traditional packaging. This interconnection method not only significantly shortens the signal transmission path, but also significantly reduces parasitic inductance and resistance, thereby effectively improving the electrical performance of the chip. At the same time, the solution integrates wafer level micro bump technology, with a minimum solder ball spacing of 0.3mm, which can meet the packaging requirements of high-density I/O.

3、 Technological innovation and core advantages

Extremely slim and light package size

Through advanced wafer level packaging technology, this solution has achieved a breakthrough reduction in packaging thickness, with the thinnest reaching 0.2mm, which is more than 60% thinner than traditional QFN packaging thickness. This advantage makes the design of TWS earphones more flexible, enabling the integration of larger capacity batteries in limited space, significantly improving the product's battery life, and providing strong support for the lightweight design of earphones.

Excellent electrical performance

By using a rewiring layer (RDL) to directly interconnect chips, the signal transmission path is significantly shortened, parasitic inductance and resistance are significantly reduced, and overall electrical performance is improved by 30%. This improvement directly translates into lower latency, more stable Bluetooth connection, and better sound quality performance of TWS earphones, effectively improving the user experience.

Excellent heat dissipation capability

This solution has excellent in-plane heat dissipation capability, which can quickly and evenly distribute the heat generated during chip operation to the entire packaging surface, avoiding the formation of local hotspots. This not only improves the stability and reliability of chip operation, but also extends the service life of the chip, ensuring that TWS earphones can maintain good performance under long-term high load working conditions.

Significant cost and efficiency advantages

Due to the absence of the lead frame and carrier board used in traditional packaging, the material cost of this solution has been reduced by 25%. At the same time, the production mode of wafer level batch processing has significantly improved production efficiency, reducing the overall production cycle by 30%. These advantages help customers effectively reduce the manufacturing cost of their products and enhance their market competitiveness.

Flexible production capacity and stable yield

The solution supports full process processing of 2/4/6-inch wafers, enabling flexible production from 24-hour rapid sampling to million level batches, and can quickly respond to customer needs at different stages. Through strict process control and quality assurance system, the mass production yield remains stable at over 99.5%, ensuring a stable supply of customer products.

4、 Scheme design and process capability

High precision rewiring layer process

The core adopts high-precision rewiring layer (RDL) technology, with a minimum line width and spacing of 2 μ m/2 μ m, which can meet the requirements of high-density wiring. This process supports multi chip side to side tiling and 2-layer vertical stacking, enabling heterogeneous integration of multiple chips such as processors, memory, sensors, etc., providing customers with highly integrated system level packaging solutions.

Customized integration capability

The solution can be customized to integrate wafer level heat dissipation layers and electromagnetic shielding layers according to the specific needs of customers, meeting the EMC and heat dissipation requirements of different products. This capability enables the solution to adapt to various complex application environments, ensuring that the product can work stably and reliably under various working conditions.

Complete testing solution

Provide a complete wafer level testing (WLT) solution that enables comprehensive functional and performance testing of chips during the wafer stage, proactively screening out non-conforming chips and reducing customers' subsequent packaging and testing costs. At the same time, wafer level testing can improve testing efficiency and shorten the product launch cycle.

5、 Application value and market impact

This advanced wafer level packaging solution has been successfully applied to multiple mainstream TWS headphone products, helping customers achieve lightweight design and performance upgrades, significantly enhancing the product's market competitiveness. This solution is not only applicable to TWS earphone Bluetooth control chips, but can also be widely used in consumer electronics fields such as smart watches, wireless earbuds, AR/VR devices, which have strict requirements for size, power consumption, and cost.

With the continuous development of consumer electronics technology, advanced wafer level packaging technology will play an important role in more fields. We will continue to invest in research and development, continuously improve our technological level and capabilities, provide customers with more advanced, reliable, and efficient packaging solutions, and help promote innovation and development in the electronics industry.

VI. Summary

This case successfully verifies the application value of the dual technology route of fan out wafer level packaging (FOWLP) and wafer level chip size packaging (WLCSP) in the field of TWS earphone Bluetooth main control chip. This solution has demonstrated significant advantages in packaging size, electrical performance, heat dissipation capacity, cost control, and production efficiency, providing an effective technical approach to solving the contradiction between slimness and high performance faced by the consumer electronics industry. In the future, we will continue to deepen our cooperation with customers, promote the industrial application of advanced packaging technology, and contribute to the development of the global electronics industry.