Investigation of injection molding parameters on the uniformity of porous array of polymer microfluidic chip

Abstract

The uniformity of the porous array seriously affects the performance of the injection-molded parts. In this study, a uniform hole array chip constituted by 384 holes whose radiuses are 1.30 mm is fabricated by precision injection molding technology. To capture the relevance between the uniform dimension of the porous array and the injection molding process parameters, single factor experiment was adopted. Besides, the condensed state of the hole array was studied to give a further explanation of the inner relationship between the hole array and the most sensitive injection process. As for the measurement, the diameter of the hole which next to the gate and away from the gate was investigated by means of universal tool-measuring microscope, and the standard deviation of the hole diameter was chosen to estimate the uniformity of the hole array. Furthermore, the crystal state and interface state were characterized by polarized light microscopy (PLM), used to explain why the difference of those holes appeared. The results reveal that the impact of process parameters on the uniformity of the hole array was ranked as follows: melt temperature, cooling time, mold temperature, injection pressure, injection speed and packing pressure. Besides, the analysis of the condensed state on different melt temperature indicates that the larger grain size is less favorable to the uniform molding, as the melt temperature increases, the difference of cortical thickness between the dynamic template and fixed template sides decreases, product uniformity is improved.

Effects of Cavity Thickness on the Replication of Micro Injection Molded Parts with Microstructure Array

“…The larger the u i , the better the replication uniformity of the microstructure at this position. To compare the replication uniformity between parts, the standard deviation was introduced [10,17]. It was defined as Equation (3):…”

“…The replication uniformity will significantly influence the performances of parts with microstructure arrays [16][17][18][19]. To further improve the replication uniformity of parts, many researchers have studied the influence of the pressure and temperature distribution on microstructure replication of the molded parts [20][21][22].…”

“…In the last few years, several researchers have focused on the influences of processing parameters to improve the replication uniformity of the injection-molded parts with microstructure arrays [16,17,20,31,32]. Lucchetta et al [31] indicated that to maximize both the average values and uniformity of the microfeatures, the process parameters need to be performed at a low injection speed and a high holding pressure.…”

“…Matschuk et al [32] explored the arrays of 40 nm wide pillars and optimized process parameters to enhance the replication quality that is described by the height, width, and uniformity of the nanoscopic features. Song et al [17] investigated the effect of process parameters on the uniformity of porous arrays. However, the existing research on the influence of process parameters on the uniformity of rectangular microstructure arrays is not comprehensive.…”

Multi response optimization of injection moulding process parameters of polystyrene and polypropylene to minimize surface roughness and shrinkage’s using integrated approach of S/N ratio and composite desirability function

“…The optimal level obtained was 240 °C melt temperature, 90 °C mould temperature, 30 mm/s injection speed. Song et al (2018) have investigated the impact of the process parameters of injection moulding during the fabrication of polymer microfluid chip made of a porous array. The parameters considered during the process were mould temperature, cooling time, melt temperature, packing pressure, injection speed and injection pressure.…”