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Design and Development of the Process of Manufacturing Microstructures by Electroforming in Molds Made by Additive Manufacturing Technology

Rabiei Motmaen, Farid | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58093 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Akbari, Javad
  7. Abstract:
  8. Today, the need to use microstructures in various fields of industry has led many countries around the world to take action to produce micro and miniature structures and make investments in this field, because the small size of the structures, increase production speed and reduces costs. Meanwhile, high-aspect-ratio metal microstructures are widely used in various and influential industries in the world, including the automotive, missile and military chip industries. LIGA and WIRECUT methods are two common methods of producing metal microstructures with high aspect ratio. In the LIGA method, making a mask requires expensive materials and equipment and has complex steps. In addition, the X-ray synchronous machine is an expensive machine for curing polymer molds. The health of the operator is also at risk due to the use of X-ray. In addition, in the LIGA method in order to make changes in the design and size of the microstructures a new mask must be created to. On the other hand, the WIRECUT method is expensive and complex due to the use of expensive equipment and is not suitable for mass production. But in the proposed alternative method, the molds were made by additive manufacturing technology that eliminated the need for X-ray, expensive equipment, and complex steps. In addition, it has flexibility in making changes to the design and size of microstructures. In the proposed method, the molds were first designed in SOLIDWORK 2020 software and then made by LCD resin additive manufacturing machine. The molds were placed on a conductive substrate and by filling the negative sections of the mold in the process of acid copper electroforming, metal microstructures with high aspect ratio (15) were produced. Finally, the optimal parameters of the method to achieve the best product were investigated. Layer thickness and exposure time were resin mold making variables and electric current density was considered as input variable in electroforming process. Dimensional accuracy, surface smoothness and hardness were the outputs of the method. Dimensional accuracy depends on the exposure time and layer thickness in making the resin mold. For a layer thickness of 50µm the appropriate exposure time is 5sec and for a layer thickness of100µm is 6sec. The surface roughness of microstructures depends only on the thickness of the layer in the construction of the resin mold, the minimum value of RZ was 7µm was obtained in the layer thickness of 50µm. Hardness depends only on the density of electric current in the electroforming process, the maximum value (115 HV) was obtained at a current density of 1A/dm2
  9. Keywords:
  10. Additive Manufacturing ; Electroforming ; High Aspect Ratio ; Rapid Prototyping ; Microminiaturization ; Metal Microstructures

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