Impedance Controlled Wirebond with Reference Conductor

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Solution Overview

Problem

Wire-bonding in microelectronic assemblies leads to electromagnetic interference and impedance issues due to electromagnetic transmissions along wires, which become more pronounced as chip frequencies increase and pitch between contacts decreases, causing unwanted radiation and noise.

Innovation Solution

Incorporating reference conductors, such as wirebonds, that are connectable to a stable potential source and spaced uniformly from signal conductors to achieve a desired impedance, with these reference conductors extending in parallel or at angles to signal conductors over a substantial portion of their length, thereby reducing electromagnetic interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wire-bonding is used to connect microelectronic chip contacts to other electronic components, then electrical connection is achieved, but electromagnetic interference and impedance issues occur due to electromagnetic transmissions along the wires

Engineering Contradiction:

Improvesignal transmission stabilityVSAvoidelectromagnetic interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces reference conductors as intermediary elements that run parallel to signal wirebonds. These reference conductors are connected to a stable potential source and serve as a mediator to control the electromagnetic field distribution around the signal conductor, thereby maintaining desired impedance and reducing electromagnetic interference without affecting the signal transmission function

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent controls the spacing between reference conductors and signal wirebonds to achieve a desired impedance value. By adjusting this geometric parameter (spacing distance), the characteristic impedance of the signal transmission path is controlled, which resolves the impedance issues that arise from conventional wire-bonding

Inventive Principle:

Principle #35Parameter changes

2Area of stationary object

If the pitch between contacts on microelectronic chips is reduced to increase integration density, then area utilization is improved, but electromagnetic interference and impedance problems become more serious

Engineering Contradiction:

Improvearea utilizationVSAvoidelectromagnetic interference

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies reference conductors selectively near signal wirebonds that are susceptible to interference or where impedance control is critical. This local application of reference conductors provides targeted electromagnetic field control in high-density areas without requiring reference conductors for all connections, thus maintaining area efficiency while addressing interference problems in critical regions

Inventive Principle:

Principle #3Local quality

3Reliability

If wire-bonding is used for connecting microelectronic devices, then electrical connection is established, but unwanted radiation and detuning of the line occur due to electromagnetic transmissions

Engineering Contradiction:

Improveconnection stabilityVSAvoidunwanted radiation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

Reference conductors act as intermediary elements that provide a controlled return path for electromagnetic fields. By running parallel to signal wirebonds and being connected to a stable potential source, they mediate the electromagnetic field distribution, preventing field lines from radiating into surrounding space and causing unwanted radiation and detuning

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration effectively minimizes electromagnetic interference and impedance issues, ensuring stable signal transmission by maintaining a desired impedance in microelectronic assemblies, even at higher frequencies and smaller pitch distances.

Implementation Method 1

electromagnetic transmissions along a wire can extend into space surrounding the wire, inducing currents in nearby conductors

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a wirebonding tool attaches the end of a wire to a pad on a microelectronic chip using thermal and/or ultrasonic energy

Methodology Applied

Scientific EffectThermal energy: Heating

Implementation Method 3

a wirebonding tool attaches the end of a wire to a pad on a microelectronic chip using thermal and/or ultrasonic energy

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Data Source

PatentUS9030031B2Microelectronic assembly with impedance controlled wirebond and reference wirebond

Publication Date: 2015.05.12 ADEIA SEMICONDUCTOR SOLUTIONS LLC

AI summary

A microelectronic assembly includes a microelectronic device, e.g., semiconductor chip, connected with an interconnection element, e.g., substrate. The reference contacts are connectable to a source of reference potential such as ground or a voltage source used for power. Signal conductors, e.g., wirebonds are connected to device contacts exposed at a surface of the microelectronic device. Reference conductors, e.g., wirebonds can be connected with two reference contacts of the interconnection element. A reference wirebond may extend at a substantially uniform spacing from a signal conductor, e.g., wirebond connected to the microelectronic device over at least a substantial portion of the length of the signal conductor, such that a desired impedance may be achieved for the signal conductor.