Laser Plastic Welding Technology: A Reliable Solution for Welding Plastic Components | MachineMFG

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Laser Plastic Welding Technology: A Reliable Solution for Welding Plastic Components


Approximately 60 years ago, Theodore Maiman created the first beam of light using a ruby laser, even though he didn’t know what application this laser would have in the future.

Now, it’s hard to imagine performing micro-fabrication without using lasers as a critical processing tool. With lasers, we can shape, drill and cut materials. Moreover, material bonding is another important advantage of laser processing.

What would happen if water penetrated the housing of sensitive electronic components? Would adhesives affect the liquid purity within microfluidic plastic parts?

The cost of replacing electronic products would be highest in the first case, while in the latter case, it could immediately endanger life. Connection technology used in plastic component assembly plays a decisive role in determining the quality and durability of the overall product.

Laser Technology Assists in Precision Welding of Plastics

Connecting two injection molded plastic parts can be accomplished through chemical, thermal or mechanical methods, depending on the product’s final application and different aesthetic requirements.

However, connecting plastic components under harsh or sensitive conditions poses a significant challenge. For small electronic housings, plastic parts need to be accurately, reliably, and stably joined without any chemical, thermal, or mechanical stress caused by the materials.

Laser Welding Technology

Laser welding technology is different from other common joining techniques; it is a clean and particle-free process. Laser plastic welding systems can be integrated with cleanroom packaging arrangements and offer various possibilities for online process monitoring.

The principle of laser plastic welding is that the laser beam penetrates the upper transparent material layer and reaches the surface of the lower absorbent material layer. The laser energy is converted into thermal energy, causing surface melting.

At the same time, heat is transferred by conduction from the bottom surface to the contact surface of the upper transparent workpiece, causing it to melt and achieve micro-thermal fusion welding. This has been extensively validated through various quality control methods during the welding process.

Figure 1 Sealed shell of RFID tag with built-in sensor
Figure 2 Laser beam generates heat at the weld seam. Through heat conduction, the upper connection area will also melt.

The principle of laser welding clearly indicates that compared with other welding technologies, laser welding consumes much less energy on the components because only a narrow area surrounding the weld is heated.

Depending on the material to be welded and the desired welding strength, the width of the weld ranges from a few tenths of a millimeter to 1 millimeter. The laser spot diameter can be adjusted within this range according to specific applications.

Laser welding technology has many unique advantages. For example, electronic components to be encapsulated can have narrow edges, and the electronic components are not affected during the welding process.

In addition, due to the characteristics of the laser welding system itself, this connection technology has created new degrees of freedom in product engineering design, physical design, and material selection.

Figure 3 The enlarged image shows the weld quality of different processes
  • The image on the left shows a weld seam produced by laser plastic welding magnified 150 times;
  • The image in the middle shows a weld seam produced by hot plate welding magnified 50 times;
  • The image on the right shows a weld seam produced by vibration welding magnified 50 times.

Comparison With Other Joining Technologies

Electronic device assembly is very sensitive to vibration and particles. Since laser transmission welding does not produce any mechanical stress or chemical reactions, and its thermal effect is limited to a small area near the weld, laser plastic welding is a reliable and non-destructive welding method, making it suitable for encapsulating electronic components.

Traditional plastic welding techniques, such as ultrasonic welding or friction welding, heat the parts through friction. Due to their inherent technical shortcomings, they are not suitable for encapsulation processes of electronic components. This joining method may also form particles in addition to producing mechanical stress.

Another way of connecting through adhesion introduces additives into the product, which is usually undesirable, especially in the medical industry. Even in parts with risk level Ha, the use of adhesion can lead to significant delays in product launch time because the adhesive introduced into the product must pass the corresponding certification.

Furthermore, hot plate welding transfers a large amount of energy into the material and may cause internal stress, leaving sink marks on susceptible surfaces.

The Impact of Laser Plastic Welding on Electronic Devices and Microfluidics

Laser plastic welding technology can improve the safety level of electronic or microfluidic products. The absence of particle generation, high cleanliness, and high geometric freedom are prerequisites for product manufacturing.

Laser plastic welding technology can ensure the high-quality completion of products. Laser plastic welding technology is suitable for forming fine geometric channels in microfluidic products and easily welding plastic housings of automotive sensors.

To facilitate the integration of laser welding systems into production lines, a variety of solutions can be directly integrated into mass production lines or processed as standalone equipment. The laser plastic welding system can be connected to the user’s MES, and the operation of the system software is extremely simple. The welding speed can be adjusted according to the material to be welded and the required stability.

The power used in welding needs to be determined based on specific applications or welding materials, and can range from a few watts to a higher power range.

For example, welding high-temperature-resistant materials requires higher power. The choice of laser source is also based on specific application requirements, such as using semiconductor lasers or fiber-coupled lasers.

Easy Operation

From project setup to completing high-quality welding components, only a few steps are needed. The perfect combination of hardware and software plays an important role in the use of the system. Users only need to click the mouse, and the welding contour can be automatically generated and directly converted into a perfect welding result in the calibrated work area.

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