Technical Paper
Identifying the root cause of particle contaminationin electronic automotive components

ZEISS Technical Cleanliness Solutions

Particle contamination in battery production is the enemy
of product efficiency, functionality, and longevity.

Production processes, the production environment, and the final packaging all have an influence on component
cleanliness. As a result, compliance agreements with limiting values often need to be implemented between thecustomer and supplier or between product development and production. This means that the cleanliness requirements
are not fixed and can be specifically chosen by the customer in accordance with the product geometry function,manufacturability, and verifiability of the component.

Technical cleanliness is attracting increased attention in industry

The quality solution: technical cleanliness.

because it promotes the efficiency and effectiveness of individual

But what is technical cleanliness?

industrial products. Not only does it begin with the suppliers
at the very start of the production chain, it is applicable to all

Technical cleanliness is a two-stage procedure that uses a lightindustries – covering implants in the field of medical technology,

microscope to examine the number and size of particles present,engine components and assemblies in automotive settings, andthen deploys an electron microscope to confirm the chemicaleven fuels and lubricants in aerospace. Particulate contamination

composition and origin of the particles. It therefore seeks to

may impair performance in the automotive industry by migrating

eliminate system failures that could potentially be caused byfrom previously non-critical areas to sensitive locations such asthese particles. The necessary level of technical cleanlinesssemiconductors, with metallic and non-metallic particles thatis determined on the basis of the particle-sensitive points ongather on these parts causing the car to malfunction or eventhe system in question. The relevant particles may also differ

stopping the engine.

in character – while combustion engines typically encounter

This paper specifically addresses particle contamination on ahard and abrasive metallic particles, electronic engines canlithium-ion battery. Though this issue is primarily associated withbe susceptible to low- and high-conductivity particles. Most

the automotive industry at present, it is also of wider relevanceparticles are generated during the processing of components

for many other industries.

and assemblies (approx. 80%) and only a fraction (approx.
20%) are due to environmental influences. Since manufacturers
cannot address every possible malfunction and manufacturing
process, the aim here is to focus on metallic particles.

VDA 19/ISO 16232 was established as a standard for enablingcustomers and suppliers to address the risk of potential damage
to products across the production chain. In the electronics
industry, VDA 19 does not specify any limiting values forcomponent cleanliness. These must be defined according tocomponent function, producibility, and verifiability. When
residual contamination is sufficiently low, the system isconsidered adequately clean.

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VDA 19.2: a brief overview

Contamination errors in the manufacturing processof an ion battery

The aim of VDA 19.2 is to prevent critical particulatecontamination at sensitive sites, to remove unavoidable particles,

Lithium-ion batteries are very sensitive to contamination in theand to protect components and assembled systems against themanufacturing process. Contamination in the form of particulate,entry of particles from the surroundings. As well as targetingionic contamination, and even water can all cause significant levels

these technical goals, the guideline also helps standardizeof defects in the finished product.

procedures for planning and optimizing cleanliness-sensitive

A moisture environment can react with active materials and renderassembly areas. It is essential for the product development

them non-functional, which is why the manufacturing processprocess.

needs to be undertaken in an extremely dry environment. ThisThe Illig method, as described in the VDA 19.2 standard, isresults in very high static charges during the process and causes

used to test the cleanliness of a given location based on its

the attraction of particles. These particles present a high risk ofenvironmental conditions – such as air or workbenches. Particle

penetrating the separator foil and thereby causing short circuits.

traps make it possible to analyze the number of sedimented

The consequences of lithium-ion battery contamination are only

particles per time unit (Illig value). The detected particle number

seen when the end customer puts the battery into operation.

per size class is multiplied by a weighting factor, added up, andnormalized to calculate the Illig value. This Illig value is generated

Cleanliness – preventing particle contamination

by normalizing the sum value to an area of 1000 cm2 and ameasuring time of 1 h. The calculated Illig value provides the basis

Metallic particles present a higher risk of damaging the battery

for comparing the collected particle contamination at different

cell, which can cause lithium dendrite growth, an electrical short,locations over a certain time period. With the Illig formula, larger

or thermal runaway – a significant safety issue for the lithium-ion

particles are more heavily weighted than smaller ones as thebattery. These metallic particles can easily be accumulated whenformer are more likely to have a higher damage potential.

transporting the battery or during the manufacturing process,with every metallic particle over the size of 5 μm considered
critical for the battery. Since the blade cutter is the main root

Ion battery structurecause of metal burrs on copper and aluminum, users must makea trade-off between quality and cost in deciding when to change

All lithium-ion batteries share the same fundamental structure,

the blade.

comprising an anode and a cathode that need to be kept a fixedWorking in combination with the ZEISS Technical Cleanlinessdistance apart. They also feature an electrolyte that lets theAnalysis (TCA) software, ZEISS light microscopes provide

charge transfer from one electrode to the other.

quantitative particle analysis that distinguishes between theFoils act as the separator in such batteries. Not only must this bemetal, fiber, and non-metal particle types down to a size of 1

Battery Cathode Particles

Conductive additivePolymerbinder

Lithium cobalt oxide(LiCoO2) cathodeparticle

GeminiSEM, Beam energy 600 V, Inlens SE imageZEISS

22 June 2022

sufficiently flexible to preventµm. Electron microscopes from ZEISS instantly state the chemical

short circuits by maintaining

composition of each particle. ZEISS technical cleanliness solutions

the necessary gap between

therefore offer ideal imaging for diverse customer groups fromthe electrodes, it needs to be

R&D through to mass production.

structured in a way that allows

And the intuitive correlative workflow implemented by ZEISS,

the ions generated in thewhich ensures perfect interplay between the hardware

electrolyte to pass through.

and software, makes it easy to move from light to electron

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microscopes.

BATTERY CATHODE PARTICLESElectron Microscopy
with EDSZEISS SmartPI
Quantification & advanced classification

HARDWARE

SOFTWARE

Run-upCalibrate

Move

CaptureReporting
SmartPI Reporter

DetectMeasureAnalyze

Report3

Battery Anode Cross-section
Electric vehicle battery contamination
Battery cells handle highly complex and electrochemical processes
that form the most important part of an electric car. A vehicle
battery must withstand many challenges relating to aspects suchas its size, the different components from which it is made, andthe high voltages transferred by these components. Any particle
contamination in the processed part can affect the lifetimeand quality of the battery. Iron particles located at the anode,cathode, or separator can cause the battery cell to self-discharge.
And since contamination may also cause overheating that leads tothe destruction of the battery cell, technical cleanliness within themanufacturing process is more important than ever.

BATTERY ANODE CROSS-SECTION

Mixed graphite and silicon (bright particles) lithium-ion battery anode cross-section. The superior elemental contrast of thebackscatter (EsB) detector allows easy identification of the included silicon particles. GeminiSEM, 2 kV accelerating voltage,ZEISS

22 June 202

Quality gates during battery development
and production
Battery manufacturers cannot take shortcuts on quality if they wish to become
Quality assurance begins with research and development, continues through every
step of production, and even affects how the raw materials are processed forassembly of the battery modules.

Carl Zeiss IQS Deutschland GmbH
Carl-Zeiss-Straße 2273447 Oberkochen

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Maple Grove, MN 55369/USA

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EN_60_010_0040I Created in Germany CZ-2022
Subject to change in design and scope of delivery and as a result of ongoing technical development.

serious players in the growing market for new energy vehicles (NEVs).

www.zeiss.de/imt

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