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Equation 7 · Part 2 · Comparing the Main Approaches to Chiplets and Advanced Packaging

subscript

Rth,iR_{\mathrm{th},i}
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

where P is the power dissipated at that tier and each Rth,iR_{\mathrm{th},i} is the thermal resistance of one layer already between that tier and the heat sink — die bulk, bonding interface, or an intervening active tier. A tier two layers from the heat-removal face inherits the resistance of everything below it in a way a single die never does, which is why thermal co-design and power-tier placement, not raw stack height, are what determine whether a given 3D design is thermally viable.

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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.