Compliant Pin Normal Force Transducer with Strain Gauge

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Solution Overview

Problem

Current methods lack the ability to accurately and easily measure the force deflection characteristics of compliant pins used in solderless terminations between electrical contacts and plated vias in printed wiring boards, leading to potential damage or poor electrical performance due to insufficient or excessive normal force.

Innovation Solution

A transducer system comprising a fixture with a supporting beam and a sensing beam, equipped with a strain gauge array, which measures the strain caused by the compliant pin's deformation to determine the normal force exerted, allowing for precise force-deflection characteristic evaluation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If computer modeling methods (ANSYS) are used to predict normal forces, then the measurement process becomes simpler, but the accuracy of the predicted normal forces deteriorates due to insufficient data and model inaccuracies

Engineering Contradiction:

Improvesimplicity of measurement processVSAvoidaccuracy of normal force prediction

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent replaces computer modeling methods with a mechanical measurement system. A physical transducer device with a beam and strain gauge directly measures the normal force exerted by the compliant pin, substituting the virtual modeling approach with a concrete mechanical measurement system that provides accurate experimental data.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a transducer device as an intermediary between the compliant pin and the measurement system. The transducer includes a beam that deforms under the pin's force and a strain gauge that detects this deformation, serving as a mediator that converts mechanical force into measurable electrical signals for accurate normal force determination.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If compliant pin designs become smaller, then the application scope increases, but the normal forces are reduced making compression of copper in plated vias a greater factor affecting final normal force

Engineering Contradiction:

Improveapplication scope of compliant pinsVSAvoidaccuracy of normal force measurement

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent employs parameter changes by designing the transducer beam with specific geometric parameters (length, width, thickness) and material properties that are optimized for measuring small forces. The beam's dimensions and the strain gauge placement are carefully selected to provide sufficient measurement sensitivity even when normal forces are reduced in smaller pin designs.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If excessive force is applied by compliant pins, then electrical contact is improved, but damage to plated vias or through holes occurs

Engineering Contradiction:

Improveelectrical contact qualityVSAvoiddamage to plated vias

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements feedback by measuring the actual normal force exerted by the compliant pin and using this information to evaluate whether the force is within acceptable ranges. The strain gauge measurement provides feedback that indicates whether the pin is applying sufficient force for reliable electrical contact or excessive force that could damage the plated via, enabling design optimization.

Inventive Principle:

Principle #23Feedback

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

Provides accurate measurements of normal force, enabling the verification and improvement of computer models, ensuring optimal design and performance of compliant pins by directly measuring force-deflection characteristics, thus preventing damage to plated vias and ensuring reliable electrical contact.

Implementation Method 1

A strain gauge array is provided on the sensing beam for sensing strain of the sensing beam. The strain of the sensing beam corresponds to normal force imparted on the sensing beam by the compliant pin.

Methodology Applied

Scientific EffectStrain gauge sensing: Piezoresistive Effect

Implementation Method 2

The sensing beam is configured to be deformed when the compliant pin is loaded into the slot and the deformation corresponds to strain of the sensing beam configured to be sensed by the strain gauge array.

Methodology Applied

Scientific EffectBeam deformation: Elasticity

Data Source

PatentUS8935964B2Transducer for and method of measuring normal force of a compliant pin

Publication Date: 2015.01.20 TE CONNECTIVITY SOLUTIONS GMBH

AI summary

A transducer for measuring normal force of a compliant pin includes a fixture having a base. A supporting beam extends from the base. A sensing beam is positioned proximate to the sensing beam and supported at at least one end thereof. The fixture has a slot positioned between the supporting beam and the sensing beam and configured to receive the compliant pin. A strain gauge array is provided on the sensing beam for sensing strain of the sensing beam. The strain of the sensing beam corresponds to normal force imparted on the sensing beam by the compliant pin. The sensing beam is configured to be deformed when the compliant pin is loaded into the slot and the deformation corresponds to strain of the sensing beam configured to be sensed by the strain gauge array.