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Wire Bond Length Calculator

Work out wire bond length instantly with clear inputs, formula shown and shareable results.

About Wire Bond Length Calculator

Bond wire length is the span from pad to lead plus the loop, with about 15% added for the arc. The number that matters electrically is inductance: roughly 1 nH per millimetre, which at gigahertz frequencies is the dominant parasitic in a wire-bonded package.

Formula

Bond wire

length approx 1.15 x sqrt(span^2 + loop^2); inductance approx 1 nH per mm

Worked example

With the default values below, Wire Bond Length Calculator returns Average wire length of 2.08. Change any input above and every figure here is recalculated in your browser.

Inputs used

Die side length
8 mm
Die edge to lead frame distance
1.8 mm
Bond loop height
0.15 mm
Wire bonds
256 bonds

Results

Average wire length
2.08 mm
Total wire length
531.76 mm
Bond wire inductance
2.08 nH
Bond wire resistance
103,250.71 mΩ

Step by step

  1. 1Values used
  2. 2Bond wire
  3. 3Average wire length= 2.08 mm
  4. 4Total wire length= 531.76 mm
  5. 5Bond wire inductance= 2.08 nH
  6. 6Bond wire resistance= 103,250.71 mΩ

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why is 1 nH per mm such an important number?

At 1 GHz, 1 nH is 6.3 ohms of reactance. A 2 mm supply bond therefore presents 12 ohms, which is why flip-chip replaced wire bonding for high-speed parts.

How is bond inductance reduced?

Shorter wires, multiple parallel bonds for supplies, down-bonds to the paddle, or moving to flip-chip where the bump inductance is tens of picohenries.

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