IC Chip Offset Pads Layering Crack Resistance

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Integrated-circuit chips with projecting external contact pads face mechanical weakness and risk of cracks during assembly due to hollowed end faces and potential electrochemical reactions between aluminum internal pads and gold external pads, leading to connection failures.

Innovation Solution

The chip design features first and second electrical connection means covered by intermediate and superficial dielectric layers, with external pads formed on flat zones of the superficial layer and vias connecting them to the internal pads, enhancing mechanical strength and reducing the risk of cracks through a structured layering approach.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If growth deposition is used to produce external contact pads in openings of the superficial layer, then the external contact pads can be formed with proper electrical connection, but the end faces become hollowed with weakened peripheral rims that are prone to cracking during assembly

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidmechanical strength of superficial layer

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent transitions from producing contact pads only within openings to producing pads on flat zones of the superficial layer that extend beyond the openings. This dimensional change allows the pads to have both proper electrical connection areas and sufficient mechanical support from the surrounding layer, eliminating the hollowed appearance and weakness.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent creates different zones on the contact pad structure: central zones for electrical connection and peripheral zones for mechanical strength. The pads are produced to extend selectively over the openings while maintaining flat zones on the superficial layer, providing local differentiation between electrical function and structural support.

Inventive Principle:

Principle #3Local quality

2Reliability

If high pressure is applied during assembly to establish electrical connections through the hollowed contact pads, then electrical connections can be established, but cracks appear in the weakened superficial layer leading to internal corrosion

Engineering Contradiction:

Improveelectrical connection establishmentVSAvoidcracks and internal corrosion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent strengthens the structure beforehand by producing contact pads on flat zones that extend beyond the openings. This pre-reinforcement provides mechanical cushioning during assembly, allowing high pressure to be applied for electrical connection without causing cracks in the superficial layer.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If aluminum internal pads and gold external contact pads are used, then proper electrical functionality is achieved, but electrochemical reactions occur that expand material and damage electrical connections

Engineering Contradiction:

Improveelectrical functionalityVSAvoidelectrochemical reactions and material expansion

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an intermediate dielectric layer between the aluminum internal pads and the gold external contact pads. This intermediary structure prevents direct contact between the dissimilar metals, thereby preventing galvanic corrosion and electrochemical reactions while maintaining electrical functionality through the dielectric medium.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Ease of manufacture

If the superficial layer is weakened around external contact pads to allow pad formation, then contact pads can be produced, but the layer becomes vulnerable to cracking during high-pressure assembly operations

Engineering Contradiction:

Improvecontact pad productionVSAvoidresistance to cracking during assembly

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent segments the contact pad structure into multiple functional zones: openings for electrical connection, flat zones on the superficial layer for pad formation, and peripheral extension zones for mechanical strength. This segmentation allows each zone to fulfill its specific function without compromising the overall structural integrity.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS7701047B2Integrated-circuit chip with offset external pads and method for fabricating such a chip

Publication Date: 2010.04.20 MICROELECTRONIC INNOVATIONS LLC

AI summary

An integrated-circuit chip includes a first electrical connection are placed on an underlying layer and covered with an intermediate dielectric layer. A second electrical connection is placed on the intermediate dielectric layer and is covered with a superficial dielectric layer. External electrical connection pads are placed on the superficial dielectric layer and extend selectively over the first electrical connection. Vias pass through the superficial dielectric layer and the intermediate dielectric layer to make connection between the first electrical connection and the external electrical connection pads.