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Equation 11 · Part 2 · When the Substrate Became the Product

subscript

CfixC_{\mathrm{fix}}
subscript

What this part means

The lower label selects a particular version, component, or indexed member of the quantity. For example, x₀ and xₜ can be values at different positions.

Its job in the formula

A subscript distinguishes a version, component, step, or member of a quantity. It does not automatically mean multiplication.

The passage around this formula

Within its range of validity, the model explains the entire strategy of advanced packaging. Shorten ℓ\ell and you reduce the wire term. Reduce the connector pitch and you shrink CfixC_{\mathrm{fix}} per wire while getting more wires per millimetre of die edge, so you can lower the per-wire data rate for the same aggregate bandwidth — and a lower rate lets you drop the swing and delete the equalisation circuitry. The gains compound, which is why the reported numbers for short-reach parallel interfaces are so far below what a long-reach serial link costs.

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Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

Open the illustrated subscripts: which member of a family? guide →

Sources cited in the article section

These citations provide research context; check each source for the exact claim it supports.