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Compact Disc

This comprehensive guide explores the intricate processes involved in compact disc manufacturing, from the creation of glass molds to the application of photoresists. It covers essential topics such as the use of DNQ-Novolac photoresist and the importance of spin-coating for achieving even layers. The document delves into the hydrolysis of bonds, quality assurance testing, and advanced techniques like electroforming and vacuum sputtering. Furthermore, it discusses the implications of volumetric data storage and the innovative use of photopolymer systems for holographic exposure and data retention.

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Compact Disc

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  1. Ben Chlebina BabajideFalae Leah Geyer Corey Gladieux Compact Disc

  2. Making the Mold: Master • Master • Glass • Adhesive • Photoresist polymer • Spin coated • PGMEA solvent • Even layer DNQ-Novolac Photoresist Adhesive Silica Glass

  3. Making the Mold: Photoresist • Polymer: • Novolac (PF) • Diazonaphtholquinone (DNQ) • Region struck by light • Hydrolysis of bonds • Soluble in Alkali solution • Series of pits and lands • Spiral Out • Process • Dust free • Expensive

  4. Electroforming • Aluminum Plating • Electroforming • Master Makes a Father (red) • Father makes a Mother (Purple) • Mothermakes a Son (Green) • Son or Stamper becomes the mold • Quality assurance testing

  5. PC Chemical Structure

  6. Polycarbonate Disc Manufacturing Heated to a high temperature to remove impurities, especially water. Polymer additives are added to change the refractive index of the polymer. T Managed at 300 °C PC is injection molded into the master. Even polymer flow is crucial PC is expensive but economical!

  7. Metal Reflective Layer • Sputtering • Vacuum Chamber (10E-3 Torr) • Target Metal (typically aluminum or gold) • Heated to point of evaporation • Plasma-vapor target metal deposits on disc as it spins

  8. Protective Coating • Coat of Acrylic Lacquer is added • Cured by UV light • Maintains and stabilizes the etched pattern and protects the reflective surface

  9. Light Scattering-Laser Reflection • Interference pattern created by changes in pathlength of laser light

  10. Devices that use CDs must meet industry standard (light with specific wavelength) • Photo-electric cell receives light pattern and device translates the pattern into a digital signal that can be used to output information

  11. It’s a 3D World • Increased need for greater data storage capacity • Current information is stored in a 2D plane • Volume Homography allows data to be stored in 3 dimensions

  12. Volume Homography • Information is stored throughout the volume of a photosensitive material • Two coherent laser beams; the object beam and the reference beam • The two beams cause multiple interference patterns (holograms)

  13. Photopolymer Systems • Consist of a mixture of monomer and photoinitiator dissolved in a thick, cross-linked network • Holographic exposure causes polymerization • Generates a concentration gradient • Results in permanent compositional and density change

  14. Problems Arise • Writing induced shrinkage • The data stored has moved from its original position • Monomers must have low viscosities for efficient diffusion, do not lead to appreciable shrinkage on polymerization and possess a high refractive index • Highly Branched DendriticMacromonomers

  15. DendriticMacromonomers • Large volume to functional group ratio • Highly branched molecular architecture maintains a low viscosity • Incorporation of numerous high refractive index moieties at the chain ends increases the average refractive index of the macromonomer

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