Bump-on-Trace Layout Compensation for Thermal Expansion Bridging

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The interconnect structures in modern integrated circuits, including bump-on-trace (BOT) connections, face limitations in performance and density due to thermal expansion mismatch between package components, leading to potential bridging issues between metal traces.

Innovation Solution

A design calculator is used to determine the layout of package components by calculating the misalignment of metal pillars and solder bumps relative to landing traces, compensating for differences in coefficients of thermal expansion (CTE) between components, and adjusting the layout to prevent bridging during the bonding process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If package components are bonded together using standard layout design, then manufacturing process is simple, but thermal expansion mismatch causes misalignment between metal pillars/solder bumps and landing traces leading to bridging

Engineering Contradiction:

Improveconnection reliabilityVSAvoidlayout design complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by calculating and compensating for thermal expansion mismatch before the actual bonding process. The system determines coefficients of thermal expansion for each package component, calculates expected misalignment, and adjusts the layout of metal pillars and solder bumps in advance to account for this misalignment. This preliminary compensation ensures that even after thermal expansion during bonding, the connectors remain properly aligned with landing traces, preventing bridging without requiring complex real-time control during manufacturing.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If metal pillars and solder bumps are aligned perfectly with landing traces in the design layout, then manufacturing is easier, but thermal expansion during bonding causes misalignment and bridging

Engineering Contradiction:

Improvebridging preventionVSAvoidconnector alignment precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary anti-action by intentionally introducing a compensatory misalignment in the design layout that opposes the expected thermal expansion misalignment. The system calculates the thermal expansion characteristics of each package component and adjusts the positions of metal pillars and solder bumps to be deliberately offset from perfect alignment with landing traces. This preliminary anti-action ensures that when thermal expansion occurs during bonding, the components expand into proper alignment, preventing bridging between adjacent connectors.

Inventive Principle:

Principle #9Preliminary anti-action

3Adaptability or versatility

If package components with different CTE values are bonded together, then device functionality is achieved, but thermal expansion differences cause misalignment during bonding process

Engineering Contradiction:

Improvepackage component compatibilityVSAvoidtrace alignment precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the layout parameters (positions) of metal pillars and solder bumps based on the thermal expansion parameters (coefficients of thermal expansion) of each package component. The system determines CTE values for each component, calculates the expected misalignment based on these parameters, and modifies the layout parameters accordingly. This allows the system to accommodate different CTE values across various package components while maintaining alignment precision, enabling versatile component compatibility without sacrificing manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

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 effectively prevents bridging between metal traces by accounting for thermal expansion differences, ensuring reliable electrical connections and maintaining the integrity of the package structure.

Implementation Method 1

compensating for differences in coefficients of thermal expansion (CTE) between components

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS8664041B2Method for designing a package and substrate layout

Publication Date: 2014.03.04 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method and device for preventing the bridging of adjacent metal traces in a bump-on-trace structure. An embodiment comprises determining the coefficient of thermal expansion (CTE) and process parameters of the package components. The design parameters are then analyzed and the design parameters may be modified based on the CTE and process parameters of the package components.