Laser transmission welding (LTW) is a widely employed joining technique for thermoplastics microfluidic devices bonding with its distinctive advantages, such as non-contact and no relative part movement. One basic requirement for successful laser transmission welding is that one of the plastics needs to be optically transparent for the wavelength of the laser radiation with the other being laser absorbing. The current study aims to develop laser transmission welding process for the bonding of two transparent polycarbonate (PC) microfluidic substrates with the channel size of 50μm. Transparent laser absorbent material is applied on the one substrate surface to make a laser absorbing interface. A fully coupled thermal-displacement finite element (FE) model is established to simulate the performances of the welding. The process window, including laser power, scanning speed and clamping force, is derived with the modeling method. The welded channel quality, in terms of collapsed height, clogging size, and bonding strength, can meet the requirements of microfluidic device applications.
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