| Microfluidic chip technology is a technology that controls the flow and mass transfer,such as engineering,physics,chemistry,biology,nano-technology,in the micro-channel structure of micro or even nanometer scale.And many other disciplines cross the technical field.At present,the microfluidic chip preparation mainly uses the lithography process to ensure the micron size precision,and the lithography process is numerous,the operation and the preparation method are extremely complicated and cumbersome.The research group put forward the rapid mass production of microfluidic chip,and mold is the best way to make batch manufacturing in industry.Therefore,it is very important to process the regular microstructure of metal material.The microstructure of the material is mainly used in the processing of micro-processing technology,including precision machining,EDM,micro-electrolysis,LIGA technology and laser processing and other processing methods.As the microfluidic chip at a hundred micron scale,compared to the other processing methods,laser processing with a small spot size,no need to prepare electrodes and configure the solution and other characteristics,so the laser processing micro-channels is very necessary.In this paper,based on the laser micromachining technology and laser polishing technology,the composite process scheme of improving the surface quality of the micro-channel and the bottom of the runner is proposed.The main research methods and conclusions are as follows:(1)Based on the mechanism of laser micromachining,the mechanism of the interaction between laser and material is summarized,and the rationality of the experimental equipment is analyzed.The surface effect of laser processing is introduced.The absorbance of Fe laser with wavelength of 1064 nm is calculated by numerical analysis.The absorbance is about 0.36.Combined with laser as the effect of electromagnetic wave on electrons and ions,the difference between nanosecond laser and femtosecond laser is analyzed in terms of the thermal effect of laser material.It is concluded that nanosecond laser must have obvious heat conduction effect.Based on the thermo-physical properties of the materials,the latent heat of latent heat and the latent heat of gasification during the phase transition of the metal material are taken into account,and the minimum single pulse energy used in the machining process is roughly estimated without considering the influence of the pulse width.(2)The single-factor experiment of 316 L stainless steel was carried out by laser micro-machining,and then the flow width / depth trend graph was drawn to show the representative flow path morphology to study the law of size and morphology in laser micromachining.The results show that the scanning speed is too low,the flow path is over-fused and the ablation phenomenon on both sides of the machined surface is too low and the straightness of the flow path decreases.The smaller the pulse width is,the more the morphology is.,The better the flow path,the more obvious the fluctuation of the bottom of the channel.(3)The single-factor experiment of the bottom surface quality improvement of single-pulse energy and scanning speed was carried out by means of laser polishing technique.Then,the surface roughness Rt of the bottom of the flow channel was measured and the corresponding curve was drawn.The results show that with the increase of the single pulse energy,the Rt of the bottom of the runner decreases first and then increases.With the increase of the scanning speed,the Rt of the surface roughness decreases first and then decreases.(5)The solid heat conduction module was used in the COMSOL software environment to simulate the laser as a Gaussian heat source,and the temperature field distribution,gasification width and cooling process of the laser surface were simulated and simulated during the single pulse laser processing.The results show that the center temperature of the surface of the material is rapidly increasing and decreasing exponentially in the time interval of the two adjacent laser pulses,and it decreases rapidly in the range of 5μs to the melting temperature of the material.Compared with the change of pulse width,the change of single pulse energy has more obvious effect on gasification width. |
