Bonding Pad Topography for Fine-Pitch Electronic Assembly

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Solution Overview

Problem

The miniaturization of electronic apparatuses has shortened contact pitches, making it difficult to bond electronic devices to carrier boards effectively, leading to increased risks of short circuits and reduced bonding yield.

Innovation Solution

The manufacturing method involves forming first and second bonding pads with different surface topographies on a substrate and electronic devices, respectively, allowing only specific portions of the second bonding pads to contact the first bonding pads, followed by a diffusion reaction with oxidation or passivation layers to bond the devices to the substrate at a lower reaction stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If contact pitch is shortened to achieve miniaturization, then device size is reduced, but bonding difficulty increases and short circuit risk increases

Engineering Contradiction:

Improvedevice sizeVSAvoidbonding yield

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The bonding pads are designed with different surface topographies at different locations - specifically, the first bonding pad has a protruding portion that locally contacts only a specific region of the second bonding pad. This local quality differentiation ensures reliable electrical connection while preventing short circuits between adjacent pads, thus improving bonding yield despite shortened contact pitches

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The bonding interface employs asymmetric surface topographies where the first bonding pad has a protruding structure and the second bonding pad has a corresponding recessed structure. This asymmetric design creates a unique mating pattern that ensures proper alignment and contact only at intended locations, preventing misalignment-induced short circuits while maintaining miniaturization

Inventive Principle:

Principle #4Asymmetry

2Reliability

If bonding pads are brought into full contact to ensure electrical connection, then electrical conductivity is improved, but short circuit risk increases

Engineering Contradiction:

Improveelectrical connectionVSAvoidshort circuit risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The bonding pad surface is segmented into distinct contact and non-contact regions through the protruding portion design. This segmentation isolates the electrical contact function to specific localized areas, preventing unintended electrical connections between adjacent bonding pads while ensuring adequate conductivity at the intended contact points

Inventive Principle:

Principle #1Segmentation

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 approach reduces the risk of short circuits and enhances bonding yield by initiating the diffusion reaction at a lower stress, ensuring stable bonding of electronic devices to the substrate while accommodating variations in device heights and surface profiles.

Implementation Method 1

followed by a diffusion reaction with oxidation or passivation layers to bond the devices to the substrate

Methodology Applied

Scientific EffectDiffusion reaction: Diffusion

Implementation Method 2

followed by a diffusion reaction with oxidation or passivation layers to bond the devices to the substrate

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS12191277B2Manufacturing method of an electronic apparatus

Publication Date: 2025.01.07 INNOLUX CORP

AI summary

A manufacturing method of an electronic apparatus is provided, and the manufacturing method includes following steps. A substrate is provided. A plurality of first bonding pads are formed on the substrate. A plurality of electronic devices are provided, and each of the electronic devices includes at least one second bonding pad. The second bonding pads of the electronic devices corresponding to the first bonding pads are laminated onto the corresponding first bonding pads on the substrate, so as to bond the electronic devices to the substrate. The corresponding first and second bonding pads respectively have bonding surfaces with different surface topographies. The manufacturing method of the electronic apparatus is capable of reducing short circuit during a bonding process or improving a bonding yield.