Application of Plastic Laser Welding Technology in Precision Plastic Devices

Application of Plastic Laser Welding Technology in Precision Plastic Devices

Plastic laser welding is a welding method that utilizes the energy of laser photons to melt plastic workpieces at the atomic level. Today, Songsheng Optoelectronics highlights its application in the field of precision plastic electronic components. With the trend toward miniaturization of electronic/electrical components and increasingly stringent cosmetic requirements, plastic laser welding technology is rapidly being adopted across various industries.                                               

The Three Stages of Plastic Laser Welding Process: Clamping、 Heating 、Cooling 

Simultaneous Plastic Laser Welding Applications in the Electronics Industry

This technology is used for creating permanent seals in plastic enclosures for electronic applications, typically employing two methods: laser transmission welding and contour welding. In laser transmission welding, the two plastic components to be joined are clamped together while a short-wave infrared laser beam is precisely directed to the bonding area. Contour welding involves focusing the laser beam to a defined spot size through an optical lens mounted on either a motion axis or robotic arm, with the motion system moving the focal spot precisely along the weld path to complete the joining process.

Plastic laser welding is widely applied in miniaturized and lightweight precision plastic components for electronics, including computer plastic parts, smartphone components such as housings, headphone jacks and USB ports, as well as mice, connectors, switches and other plastic parts requiring precision laser welding.

Research indicates that wavelength selection is critical for optimal welding results, showing that the upper transparent material should exhibit over 50% laser transmittance while the lower absorbing material should maintain below 20% transmittance. Therefore, selecting the appropriate laser wavelength based on material properties is essential for achieving high-quality welds in plastic laser welding applications.

Selection of Plastic Laser Welding Systems

1. Classification by laser wavelength: 976nm and 2μm welding systems.

2. The 976nm laser welding system is currently widely used. Its working principle relies on the upper-layer transmission and lower-layer absorption mechanism to create joints.

3. The 2μm laser welding system simultaneously heats both upper and lower components, causing rapid temperature rise at the interface to achieve melting and bonding. This method enables welding of fully transparent components.

4. Contour scanning laser welding. This method employs servo-driven laser heads or workpiece movement to guide the laser beam along the welding path, providing sufficient energy to melt and join components. It is particularly suitable for plane-to-plane welding or products with collapse distances less than 0.1mm.

976nm Laser Welding Head (Left) and 2μm Plastic Welding Head (Right)

Songsheng Optoelectronics has independently developed two specialized welding heads for different wavelength systems:

• A 976nm coaxial temperature-measuring vision laser welding head

• A 2μm coaxial temperature-measuring imaging plastic laser welding head

These advanced systems incorporate real-time coaxial infrared temperature feedback control, enabling dynamic energy adjustment during welding to ensure process consistency and maximize yield rates.

Key Features of Plastic Laser Welding Heads：

l   Online closed-loop temperature control

l   Ultra-precision weld seams

l   Coaxial CCD monitoring interface

l   Compact and rugged design

l   Fully sealed internal structure

l   Coaxial integration (laser, temperature measurement, and imaging)

l   Compact, robust, and maintenance-free-No redundant adjustment mechanisms suitable for high-intensity automated production lines.

l   Proprietary multi-beam coaxial technology (laser, imaging, temperature measurement, and red indicator light )