Probe Card Holding Unit Retainer Force Distribution

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Solution Overview

Problem

Conventional probe cards for full wafer level tests face challenges in maintaining accurate parallelism and flatness due to warping of the clamp frame and space transformer, which affects the reliability of the conductivity test on semiconductor wafers.

Innovation Solution

A probe card design that includes a holding unit with a retainer and leaf spring, where the force application points are positioned inside the outer edges of the probe head and space transformer, preventing warp and ensuring parallelism and flatness by using a combination of retainer and leaf spring mechanisms to securely hold the probe head and space transformer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a clamp frame presses an edge portion of a space transformer to flatten a wiring substrate, then the flatness of the substrate is improved, but the clamp frame warps in the opposite direction causing loss of flatness and parallelism

Engineering Contradiction:

Improveflatness of wiring substrateVSAvoidflatness of clamp frame

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

A retainer is introduced as an intermediary component between the holding unit and the space transformer. The retainer distributes the pressing force across a broader area of the space transformer rather than concentrating it at the edge portion, preventing the clamp frame from warping while still achieving the desired flatness of the wiring substrate.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The pressing force is applied at specific locations (inside the outer edge of the space transformer) rather than uniformly across the entire edge. This localized force application prevents excessive stress concentration that would cause the clamp frame to warp, while still achieving adequate flatness where needed.

Inventive Principle:

Principle #3Local quality

2Stability of the object's composition

If a holding unit presses the edge portion of the space transformer to hold the probe head and space transformer, then the stability of the assembly is improved, but the space transformer warps causing loss of parallelism

Engineering Contradiction:

Improvestability of probe head and space transformer assemblyVSAvoidparallelism of space transformer

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The retainer serves as a mediator that distributes the holding force from the holding unit across a wider area of the space transformer. This prevents localized warping that would compromise parallelism while maintaining the stability needed to hold the probe head and space transformer assembly together.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The holding force is divided and applied at multiple discrete points (fastening holes positioned inside the outer edge) rather than as a single concentrated force. This segmentation of the force application prevents warping while maintaining overall stability of the assembly.

Inventive Principle:

Principle #1Segmentation

3Strength

If force is applied at the edge portion of the space transformer to secure the assembly, then the holding strength is improved, but the point of application causes rotational support and warp

Engineering Contradiction:

Improveholding strength of holding unitVSAvoidflatness of space transformer

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The force application points are strategically positioned inside the outer edge of the space transformer rather than at the extreme edge. This local quality change in force application maintains sufficient holding strength while avoiding the creation of rotational support that would cause warping.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The retainer acts as an intermediary that translates the holding force into a distributed pressure across the space transformer surface. This maintains the necessary holding strength while preventing the concentrated edge force that would cause warping and loss of flatness.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 design effectively suppresses warp of the probe head and space transformer, ensuring accurate parallelism and flatness with respect to a predetermined reference surface, enhancing the reliability and durability of the probe card during full wafer level tests.

Implementation Method 1

a holding unit that holds the probe head and the space transformer by pressing a portion near an edge portion of each of the probe head and the space transformer

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS8456184B2Probe card for a semiconductor wafer

Publication Date: 2013.06.04 NHK SPRING CO LTD

AI summary

A probe card is provided that is capable of accurately ensuring the flatness and the parallelism with respect to a predetermined reference surface. A point (Q) of application of force applied from a leaf spring (17) that presses a portion near an edge portion of a surface of a probe head (15) from which a plurality of probes projects over an entire circumference in a direction of a substrate to the probe head (15) is positioned inside of an outer edge of the probe head (15), and a point (P) of application of force applied from the retainer (16) that presses a portion near an edge portion of a space transformer (14) over an entire circumference in the direction of the substrate to the space transformer (14) is positioned inside of an outer edge of the space transformer (14).