Multiwire EDM Support Structure for Crack-Resistant Wafer Cutting

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Solution Overview

Problem

Multiwire electric discharge machines face challenges in reducing cracks in workpieces during the cutting process, particularly when cutting cylindrical workpieces, due to unstable machining processes and external forces applied by machining fluid.

Innovation Solution

The multiwire electric discharge machine incorporates a dummy workpiece with a curved contact surface and a pressing mechanism to support the workpiece from one side and apply pressure from another side, stabilizing the workpiece and reducing the risk of cracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a large amount of machining fluid is sprayed to prevent unstable machining process, then wire breakage is reduced, but external force applied to workpiece increases causing cracks

Engineering Contradiction:

Improvemachining process stabilityVSAvoidworkpiece cracking

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A support mechanism with a base portion is introduced as an intermediary between the workpiece and the machining system. The base portion receives and distributes the external force from the machining fluid, preventing direct transmission of this force to the workpiece that would cause cracking. The side surface of the base portion is specifically designed to face the workpiece and provide support during machining.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If machining of base portion starts when cutting wire sections reach front surface, then productivity is improved, but amount of machining rapidly increases causing workpiece cracking

Engineering Contradiction:

Improvemachining speedVSAvoidworkpiece cracking

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The support mechanism is prepared in advance with the base portion positioned to support the workpiece before machining begins. This preliminary arrangement ensures that when machining operations start, the workpiece is already stabilized and protected from cracking, even as productivity increases.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If multiple cutting wire sections are used to cut multiple thin plates simultaneously, then productivity is improved, but workpiece stability decreases making cracks more likely

Engineering Contradiction:

Improvenumber of thin plates cut per operationVSAvoidworkpiece stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The support mechanism acts as a counterbalancing element that provides stability to the workpiece when multiple cutting wire sections are used simultaneously. The base portion with its designed geometry provides a stable foundation that counteracts the destabilizing effects of multiple concurrent machining operations, preventing workpiece cracking while maintaining high productivity.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

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

This configuration effectively reduces the likelihood of cracking in workpieces by stabilizing the machining process and distributing external forces more evenly, thereby improving the precision and reliability of the cutting process.

Implementation Method 1

a voltage is applied between each of a plurality of cutting wire sections and a workpiece, and electric discharge machining is performed on the workpiece by each of the cutting wire sections

Methodology Applied

Scientific EffectElectric discharge machining: Electrical Discharge Machining

Implementation Method 2

machining fluid is sprayed from a nozzle onto a side surface of a workpiece so as to remove machining swarf from the inside of a groove formed in the workpiece by electric discharge machining

Methodology Applied

Scientific EffectFluid spray: Fluid Spray

Data Source

PatentUS12269104B2Multiwire electric discharge machine, multiwire electric discharge machining method, and semiconductor wafer manufacturing method

Publication Date: 2025.04.08 MITSUBISHI ELECTRIC CORP

AI summary

A multiwire electric discharge machine includes: a plurality of guide rollers; a machining power supply that applies a voltage between each of a plurality of cutting wire sections and a workpiece; a dummy workpiece including a contact surface curved in such a way as to be capable of coming into contact with a curved surface of the workpiece except for an end point, the end point being to be reached by each of the plurality of cutting wire sections when machining of the workpiece is completed, the dummy workpiece supporting the workpiece from one side in a first direction, the first direction being a direction in which the workpiece moves; and a pressing mechanism including a pressing portion, the pressing mechanism pressing the workpiece against the dummy workpiece by bringing the pressing portion into contact with the workpiece from another side in the first direction.