Angled Camming Contact Tip for Scrubbing Contaminants

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Solution Overview

Problem

Conventional spring-loaded contact probes face issues with high manufacturing costs and short lifespan due to costly machining operations, and they struggle to maintain reliable connections in dirty or contaminated test locations, leading to signal attenuation and frequent replacements.

Innovation Solution

A spring contact assembly with movable plungers and a compression spring featuring a compliant scrub-inducing contact tip with an angled camming surface, which provides lateral wiping movement to break through contaminants and enhance electrical conductivity, suitable for both cylindrical and flat plunger configurations, and can be manufactured using various techniques such as machining or stamping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional spring-loaded contact probes are used, then reliable electrical contact is achieved, but manufacturing cost increases and lifespan decreases

Engineering Contradiction:

Improveelectrical contact reliabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The contact tip geometry is changed from conventional to angled (e.g., 45 degrees relative to the longitudinal axis), transforming the contact mechanism from direct axial compression to angled scrubbing contact. This parameter change enables the tip to scrape through contaminants while maintaining electrical contact, improving reliability without requiring expensive machining operations for complex mechanisms

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of making the contact tip perpendicular to the probe axis for direct contact, the tip is inverted to an angled orientation. This inversion allows the contact force to have both normal and tangential components, where the tangential component provides the scrubbing action that removes contaminants, thereby improving contact reliability in contaminated environments

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If conventional contact probes are used, then electrical connection is established, but connection reliability deteriorates in contaminated environments

Engineering Contradiction:

Improveconnection reliabilityVSAvoidcontaminant interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The angled contact tip converts the harmful effect of contaminants into a beneficial scrubbing action. As the probe compresses, the angled tip naturally scrapes through oxide layers, solder flux, and other contaminants, transforming the contamination problem into a self-cleaning mechanism that improves contact reliability

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The angled contact tip performs preliminary cleaning action during the initial contact phase. Before establishing reliable electrical contact, the scrubbing action removes contaminants from the contact surface, ensuring that subsequent measurements are not affected by contamination

Inventive Principle:

Principle #10Preliminary action

3Loss of energy

If external spring probes with shorter length are used, then signal attenuation is reduced, but manufacturing cost increases

Engineering Contradiction:

Improvesignal attenuationVSAvoidmanufacturing cost

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The contact tip angle parameter is optimized to achieve effective scrubbing action within a shorter probe length. The angled geometry allows the contact point to traverse a greater effective distance through contaminants, compensating for the reduced probe length and maintaining signal quality without requiring expensive external spring probe construction

Inventive Principle:

Principle #35Parameter changes

4Ease of manufacture

If flat components are used to reduce manufacturing cost, then manufacturing cost decreases, but component lifespan decreases

Engineering Contradiction:

Improvemanufacturing costVSAvoidcomponent lifespan

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The contact tip is designed with an optimized angled geometry that distributes wear more evenly across the contact surface. The angled configuration reduces stress concentration compared to flat components, extending the operational life of stamped or formed contact tips while maintaining manufacturing cost advantages

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

The solution reduces manufacturing costs, extends the lifespan of contact probes, and ensures reliable connections by effectively scrubbing through contaminants, maintaining consistent electrical conductivity even in challenging test environments.

Implementation Method 1

a spring for biasing the travel of the plunger in the barrel

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

scrub inducing compliant electrical contact

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS8324919B2Scrub inducing compliant electrical contact

Publication Date: 2012.12.04 XCERRA CORP

AI summary

The contact assembly having a contact member with a contact tip positioned within holes in a test socket or probe plate wherein the contact tip or the hole in the probe plate or test socket has a cam surface to provide lateral movement of the contact tip across a surface of a test location during compression of the contact member to induce scrubbing on the surface of the test site.