We characterize an affordable method of producing stencils for submillimeter physical vapor deposition (PVD) by using paper and a benchtop laser cutter. Patterning electrodes or similar features on top of organic or biological substrates is generally not possible using standard photolithography. Shadow masks, traditionally made of silicon-based membranes, circumvent the need for aggressive solvents but suffer from high costs. Here, we evaluate shadow masks fabricated by CO2 laser processing from quantitative filter papers. Such papers are stiff and dimensionally stable, resilient in handling, and cut without melting or redeposition. Using two exemplary interdigitated electrode designs, we quantify the line resolution achievable with both high-quality and standard lenses, as well as the positional accuracy across multiple length scales. Additionally, we assess the gap between such laser-cut paper masks and a substrate, and quantify feature reproduction onto polycarbonate membranes. We find that ~100 µm line widths are achievable independent of lens type and that average positional accuracy is better than ±100 µm at 4”-wafer scale. Although this falls well short of the micron-size features achievable with typical shadow masks, resolution in the tenths to tens of millimeters is entirely sufficient for applications from contact pads to electrochemical cells, allowing new functionalities on fragile materials.

Injection Molding is among the most popular processes in plastic parts production. Through this process, burn marks and shrinkage play the most significant role in decreasing surface quality as well as increasing costs, especially when manufacturers use this method in order to produce thin-walled plastic parts. In this paper, a new strategy to remove the defects caused by shrinkage and burn marks has been proposed for the injection molding process of a specific plastic part which is used to keep the doors of an automobiles open during the painting process. Burn marks caused by the trapped air inside thin walls of the part were first simulated in MOLDFLOW 2010 software. Next step is to compare the simulation results to results that are obtained from experimental analysis. Then, Burn marks and shrinkage effects were eliminated by optimization of the process which includes mold design revision by means of SOLIDWORKS software, modification of the simulation in MOLDFLOW and the mold modification in workshop environment by improvising some ejector pins in certain points. Furthermore, shrinkage amount of the part after cooling process was calculated by applying Finite Element Method (FEM) and obtained results were used to optimize the design of the mold. Results demonstrate that mold design optimization would be possible through designing flawless molds that contain certain points for trapped air discharge and calculating shrinkage amount by FEM for optimization of design procedure. Results consequently decrease costs as well as providing surface quality improvement.