iPhone glass is primarily made using a process called ion exchange, which strengthens the glass making it more durable.
Here's a breakdown of the process:
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Special Glass Formulation: The glass used in iPhones, often Gorilla Glass (manufactured by Corning), is specially formulated to be receptive to the ion exchange process. This specific formulation allows for the later "stuffing" of larger ions into the glass's surface.
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Molten Salt Bath: The glass is submerged in a molten salt bath containing potassium ions (K+) at a high temperature, approximately 400 degrees Celsius.
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Ion Exchange: During this process, smaller sodium ions (Na+) present in the glass are exchanged for the larger potassium ions (K+) from the molten salt.
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Compression Layer: Because the potassium ions are larger than the sodium ions they replace, they create a state of compression on the surface of the glass. This compression is what makes the glass significantly stronger and more resistant to scratches and cracks. The larger ions literally "stuff" the surface, squeezing it together.
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Cooling and Finishing: After the ion exchange process is complete, the glass is carefully cooled and undergoes further finishing processes to ensure optical clarity and smooth edges.
In essence, the ion-exchange process creates a highly compressed outer layer on the glass, making it much harder to scratch or break. This is why iPhone screens are relatively resistant to damage, though they are not indestructible.
