LED Test Probe Head With MEM Switches for Parallel Testing

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Solution Overview

Problem

Testing small form factor light emitting diodes (LEDs), such as micro-LEDs and nano-LEDs, is challenging due to their size and the time-consuming nature of testing large numbers of them.

Innovation Solution

A probe head with electrically conductive probe needles, power supplies, multimeters, and micro-electromechanical (MEM) switches is used to create electrical connections between the needles and both a power supply and a multimeter for each LED, allowing for simultaneous measurement of voltage and current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional testing methods are used for small form factor LEDs, then testing can be performed, but testing time increases significantly and efficiency decreases

Engineering Contradiction:

Improvetesting efficiencyVSAvoidtesting time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The probe head is divided into multiple independent probe needles, each capable of independently contacting and testing individual LEDs. This segmentation allows parallel testing of multiple LEDs simultaneously, significantly reducing total testing time while maintaining the ability to test small form factor LEDs individually

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The probe head integrates power supply circuits and measurement circuits that are pre-configured and ready before testing begins. The MEM switches are pre-positioned to enable rapid connection establishment, allowing immediate power application and measurement without delay when testing commences

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If multiple LEDs are tested sequentially, then individual testing is possible, but total testing time increases

Engineering Contradiction:

Improveindividual LED measurement accuracyVSAvoidtesting throughput

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

Multiple probe needles are arranged to contact different LEDs simultaneously, with each needle pair dedicated to a specific LED. This allows parallel processing of multiple LEDs while maintaining individual measurement precision through dedicated probe contacts for each device

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The MEM switches enable continuous power application and measurement across multiple LEDs without interruption. As one LED is being tested, other LEDs can be simultaneously powered and measured, creating continuous productive action that maximizes throughput while maintaining measurement accuracy

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If probe head blocks light path, then electrical connections can be made, but optical measurement accuracy decreases

Engineering Contradiction:

Improveelectrical connection stabilityVSAvoidoptical detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The probe head is designed with probe needles that contact LEDs from the side or at an angle rather than from directly above the optical axis. This dimensional change in contact geometry allows electrical connections to be established without blocking the light path between LEDs and detectors, simultaneously achieving reliable electrical contact and accurate optical measurement

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 enables efficient testing of individual LEDs by allowing for simultaneous power application and measurement, reducing testing time and improving accuracy, especially for small form factor LEDs.

Implementation Method 1

micro-electromechanical (MEM) switches configured to create, for each of the LEDs, an electrical connection between ones of the probe needles and both a power supply and a multimeter

Methodology Applied

Scientific EffectMicro-electromechanical systems (MEM): Microelectromechanical Systems

Implementation Method 2

probe needles that are electrically conductive and configured to create electrical connections to conductive pads on light emitting diodes (LEDs)

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS20250123319A1Probe head for LED test system

Publication Date: 2025.04.17 TERADYNE INC

AI summary

An example probe head includes probe needles that are electrically conductive and configured to create electrical connections to conductive pads on light emitting diodes (LEDs) on a wafer under test; power supplies to power the LEDs; multimeters to measure at least one of a voltage across or a current through individual ones of the LEDs; and micro-electromechanical (MEM) switches configured to create, for each of the LEDs, an electrical connection between ones of the probe needles and both a power supply and a multimeter to cause the power supply to power the LED while the multimeter measures the at least one of the voltage across or the current through the LED.