Discs, often referred to as "pressed discs," are manufactured through a sophisticated, multi-stage replication process that ensures the creation of exact clones from a master.
The process of pressing discs involves a series of precise steps, transforming raw materials into durable, data-carrying optical media. This method is distinct from burning discs (which uses lasers to alter a dye layer), as pressing involves physical molding.
The Disc Pressing Process
Replicated discs are produced using high-tech injection-molding techniques, starting from an initial master copy. Here's a breakdown of the essential stages:
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Creating a Glass Master
The very first step in disc replication is the creation of a glass master. This is a highly precise, pre-recorded version of the disc's content, serving as the blueprint for all subsequent copies. It contains the exact digital information that will be replicated onto thousands or millions of discs. -
Producing Stampers
From the meticulously crafted glass master, several stampers are produced. These stampers are essentially molds, designed to make exact physical clones of the disc's surface, including all the microscopic pits and lands that represent the digital data. -
High-Tech Injection-Molding
Once the stampers are ready, they are utilized in a high-tech injection-molding process. During this stage, molten polycarbonate plastic is injected into a mold containing the stamper. The plastic cools rapidly, taking on the precise physical characteristics of the stamper, thus forming the transparent disc substrate with the data encoded on its surface. -
Adding a Reflective Aluminum Coat
After the polycarbonate disc is formed, a crucial step involves adding a coat of reflective aluminum. This incredibly thin layer is vital because it's what allows the laser in a disc player (like a CD or DVD player) to read the data by reflecting off the disc's surface. Without this reflective layer, the data would be unreadable. -
Sealing with a Protective Lacquer
Finally, the disc is sealed with a protective coat of lacquer. This clear layer serves as a barrier, safeguarding the delicate aluminum data layer and the polycarbonate substrate from scratches, dust, and environmental damage. This lacquer is then hardened by ultraviolet light to ensure its durability and longevity.
Summary of Disc Pressing Steps
To summarize the intricate journey of a pressed disc from concept to completion:
| Step | Description |
|---|---|
| 1. Glass Master Creation | The initial, precise digital data is transferred onto a specialized glass disc, forming the master blueprint for replication. |
| 2. Stamper Production | From the glass master, negative molds called stampers are manufactured. These are the tools that will physically impress the data onto each new disc. |
| 3. Injection-Molding | Molten polycarbonate is injected into molds containing the stampers, creating the physical disc with the data structure directly molded onto its surface. |
| 4. Aluminum Coating | A thin, reflective layer of aluminum is applied to the disc's data-bearing side, enabling laser readability for playback. |
| 5. Lacquer Sealing | A protective lacquer coat is applied and cured with ultraviolet light, sealing and protecting the delicate data and reflective layers from damage. |
This detailed process ensures that each pressed disc is an exact, high-quality replica of the original master, providing reliable performance for various optical media applications.
