Cantilever Probe Cleaning via Localized Crushing

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Solution Overview

Problem

Existing cantilever-probe testing heads struggle to maintain reliable electrical contact with microstructures having densely packed, small contact pads due to the risk of contact tip overtravel and potential damage during scrubbing, which is inadequate for modern integrated circuits with reduced pad sizes.

Innovation Solution

The method involves designing cantilever contact probes with a tapered, corrugated contact tip that locally mills the covering layer of the contact pad by flexing and sticking to the pad, allowing for precise removal of the oxide layer without overtravel, using a tungsten alloy with reduced diameter and specific angles for elastic deformation and minimal scrub length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional cantilever probes with hooked structure are used to clean contact pads, then electrical contact can be established, but the contact tip may overtravel and cause damage to densely packed small contact pads

Engineering Contradiction:

Improveelectrical contact reliabilityVSAvoidcontact pad damage risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the geometric parameters of the contact tip, specifically making it flat rather than hooked, and corrugated rather than smooth. This parameter change eliminates the overtravel problem while maintaining cleaning capability through localized crushing action

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of using a hooked structure that requires overtravel for cleaning, the patent inverts the approach by using a flat corrugated surface that cleans through localized crushing without requiring lateral movement, thus preventing damage to small contact pads

Inventive Principle:

Principle #13The other way round (Inversion)

2Strength

If contact tips are designed with larger diameter for durability, then mechanical strength is improved, but the scrubbing action becomes excessive and causes overtravel on small pads

Engineering Contradiction:

Improvecontact tip mechanical strengthVSAvoidcontact pad cleaning precision

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent applies local quality by making the contact tip corrugated only at the contact surface while maintaining appropriate diameter for strength. The corrugation provides localized cleaning action without requiring excessive scrubbing movement, thus preventing overtravel on small contact pads

Inventive Principle:

Principle #3Local quality

3Reliability

If traditional scrubbing method is used to remove oxide layer, then cleaning effect is achieved, but the contact tip movement causes overtravel and potential damage

Engineering Contradiction:

Improveelectrical contact qualityVSAvoidcontact stability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent substitutes the traditional mechanical scrubbing action with a localized crushing mechanism. The flat corrugated contact tip crushes the oxide layer locally without requiring lateral scrubbing movement, thus eliminating overtravel while maintaining cleaning effectiveness

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 ensures reliable electrical contact and reduces the risk of damage to the microstructure by achieving a sufficient scrub with reduced contact tip movement, effectively cleaning densely packed small contact pads while maintaining the integrity of the testing head.

Implementation Method 1

laterally flexing, by means of a tip charge, the flexible probe by keeping the stuck, so as to locally dig into a covering layer of the pad and realize a localized crushing thereof

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

mechanically engaging a free end of the flexible probe, being stuck in the pad

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS8981803B2Method for cleaning a contact pad of a microstructure and corresponding cantilever contact probe and probe testing head

Publication Date: 2015.03.17 TECHNOPROBE

AI summary

A method for cleaning a contact pad of a microstructure or device to be tested when it is in electric contact with a measure apparatus, being obtained by electrically contacting a flexible probe with said contact pad. The method includes mechanically engaging a free end of the flexible probe in a manner that sticks the free end in the pad; and laterally flexing, by a tip charge, the flexible probe in a manner that keeps the free end stuck in the pad, so as to locally dig into a covering layer of the pad and realize a localized crushing thereof.