Test Probe Current Path Segmentation for Thermal Management

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Solution Overview

Problem

Existing standard test probes for high power and high current power modules face challenges with limited lifespan due to high resistance and heat generation, which restricts their usage to lower current levels and results in reduced mating/un-mating cycles, and inadequate thermal dissipation.

Innovation Solution

An electrical test probe design featuring a test prod with a larger cross-sectional area than the elastic element, allowing most current to pass through the test prod directly, reducing heat generation and incorporating a heat sink for improved thermal dissipation, along with a power module testing system that includes a test platform and testing equipment for efficient connection and movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the test probe uses a spring as the elastic element for contact, then the contact flexibility is improved, but the resistance increases and heat generation worsens

Engineering Contradiction:
Improvecontact flexibilityVSAvoidheat generation
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The patent introduces a low-resistance conductive layer as an intermediary between the spring and the contact terminal. This conductive layer acts as a mediator that provides a preferred current path with lower resistance, while the spring maintains its mechanical function for contact flexibility. The conductive layer has much smaller resistance than the spring, so most current flows through it rather than the spring, reducing heat generation in the elastic element.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Power

If the current passes through the spring for high current testing, then the testing capability is improved, but the spring temperature increases and lifespan reduces

Engineering Contradiction:
Improvecurrent testing capabilityVSAvoidspring temperature
Core Design Contradiction:
PowerVSTemperature

Solution Approach 1:

The patent segments the current path from the mechanical contact path. The spring is separated into purely mechanical function (providing contact pressure and flexibility), while the electrical current path is separated into the conductive layer which has optimized electrical properties. This segmentation allows the spring to handle mechanical stresses without bearing the thermal burden of high current passage, thereby extending its lifespan.

Inventive Principle:
Principle #1Segmentation

3Ease of manufacture

If the test probe structure is simplified, then the manufacturing cost is reduced, but the thermal dissipation capability worsens

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidthermal dissipation
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

The patent merges the electrical contact function and thermal management function into the same conductive layer. The conductive layer that provides low-resistance current path also serves as a thermal conduction path, efficiently conducting heat away from the contact interface. This merging of functions achieves improved thermal dissipation without adding separate complex thermal management components, maintaining manufacturing simplicity.

Inventive Principle:
Principle #5Merging (Combining)

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 extends the lifespan of the test probe by minimizing heat generation and improving thermal dissipation, enabling the testing of high power modules with higher current and voltage outputs while maintaining a longer cycle life and efficient heat management.

Implementation Method 1

The tube and the test prod can have a relative movement within an elastic range of the elastic element

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The test prod has a first terminal provided to form a contact with a power module to be tested and a second terminal provided to be connected with a testing equipment

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

incorporating a heat sink for improved thermal dissipation

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3552028B1Electrical test probe and testing system using the same
Publication Date: 2022.12.07 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3552028B1 patent drawingFigure 1~2b
  • EP3552028B1 patent drawingFigure 3a~4
  • EP3552028B1 patent drawingFigure 5

AI summary

An electrical test probe (200) is presented. It comprises a test prod (210), a tube (220) and an elastic element (230). The test prod (210) has a first terminal (211) provided to form a contact with a power module to be tested and a second terminal (212) provided to be connected with a testing equipment. The test prod (210) also has a first stopper (213) between the first terminal (211) and the second terminal (212). The tube (220) has an internally extending stopper (221). The tube (220) is mounted around the test prod (210) in a longitudinal direction of the test prod (210). The elastic element (230) is accommodated between the first stopper (213) of the test prod (210) and the internally extending stopper (221) of the tube (220). The tube (220) and the test prod (210) can have a relative movement within an elastic range of the elastic element (230). The area of a cross section of the test prod (210) is much larger than the area of the cross section of the elastic element (230). A power module testing system (600) which comprises at least one electrical test probe (200) is also presented.