Technical Paper
Identify the root cause of particle contamination
for automotive electronic components

ZEISS Technical Cleanliness Solutions

Mastering failures caused by particle contamination

Particle contamination is the enemy of productimpair performance in the automotive industry by migrating

efficiency, functionality, and longevity.

from previously non-critical areas to sensitive locations such as
semiconductors, with metallic and non-metallic particles that

Production processes, the production environment, and thegather on these parts causing the car to malfunction or evenfinal packaging all have an influence on component cleanliness.

stopping the engine. This paper specifically addresses particle

As a result, compliance agreements with limiting values often

contamination on an electrical component within an automotive

need to be implemented between the customer and supplier orapplication.

between product development and production. This means thatthe cleanliness requirements are not fixed and can be specificallychosen by the customer in accordance with the product geometryfunction, manufacturability, and verifiability of the component.
Technical cleanliness is attracting increased attention in industry
because it promotes the efficiency and effectiveness of individual
industrial products. Not only does it begin with the suppliers at thevery start of the production chain, it is applicable to all industries– covering everything from implants in the field of medical
technology, engine components and assemblies in automotive
to fuels and lubricants aerospace. Particulate contamination may

Short circuits caused by conductive particle

the traces influence the current flow of the traces. A particle iscontamination:

placed over two adjacent traces, and the DC voltage between
the traces is increased from the starting point V1 up to 60 V in

One of the potential causes of a short circuit is a contaminatedincrements of 1 V. Each voltage point is applied for 5 seconds.

component. The following scenario sees a short circuit occur

The current of the voltage source is limited to 2 mA. If thewhen the electronic circuit is interrupted by various materials.

current flow is insufficient, the currently applied voltage is noted
as breakdown voltage or step voltage.

In this experiment, ZVEI (German Electrical and Electronic
Manufacturers Association) investigated whether particles on

This process was repeated until 25 breakdowns were reached.

Particles(length e.g. 500 µm; width and thickness
unspecified – from a few µm to approx. 100 µm)

Conductor (e.g. Cu, Ni, Au)
PCB(s ource: https://www.zvei.org/fileadmin/user_upload/Presse_und_Medien/Publikationen/2020/Februar/ZVEI_Technische-Sauberkeit-in-der-Elektrotechnik_
dt_engl/ZVEI_Guideline_Technical-Cleanliness-in-Electrical-Engineering_second-edition_Version-2020.pdf)

2

Comparison of Cu particles in three conditions on SAC305 PCBs%80
dry head stored70
wet heat stored60
new untreated

50
40
30
20New, untreated100

Wet heat stored
Dry heat stored
s 3V

s 5V

s 12V

s 16V

s 24V

s 48V

s 60V

(s ource: https://www.zvei.org/fileadmin/user_upload/Presse_und_Medien/Publikationen/2020/Februar/ZVEI_Technische-Sauberkeit-in-der-Elektrotechnik_
dt_engl/ZVEI_Guideline_Technical-Cleanliness-in-Electrical-Engineering_second-edition_Version-2020.pdf)

Overview of all metals in the voltage classes, rounded%80
AlSi12 above surface

70

Contact probability

AlSi12 below surface
60

CuFe2P50

Au
Cr18Ni840

Cu ETP
CuNiSi30FeSi

20

SAC305100SnZnAl4Cu1
s 3V

s 5V

s 12V

s 16V

s 24V

s 48V

s 60V

Voltage ranges(s ource: https://www.zvei.org/fileadmin/user_upload/Presse_und_Medien/Publikationen/2020/Februar/ZVEI_Technische-Sauberkeit-in-der-Elektrotechnik_
dt_engl/ZVEI_Guideline_Technical-Cleanliness-in-Electrical-Engineering_second-edition_Version-2020.pdf)

Adhesion of the particles to the PCB was observed during theComparing the results, it is apparent that the applied voltage,experiment. This is an electrothermal breakdown process inparticle state, and particle material have an influence on thewhich, as the voltage increases, a layer of impurities jerkily

contacting properties.

reduces the resistance from the megohm range to the ohm

The probability of interference varies between different particle

range.

types, but it nevertheless increases as the voltage level increases.
3

List of materials used in the test
1

Cu

Coppere.g. cables, power rails

2

CuNiSiCopper alloye.g. contact material, ­p ress-in pins

3

Au

Gold

e.g. bonding wire, connector coating

4

Sn

Pure tine.g. coatings

5

SnAg3Cu0.5 (SAC305)

Solder material

e.g. solder paste, solder bars

6

ZnAl4Cu1

Zinc alloy for die-castinge.g. housings

7AlSi12

Aluminum alloy for die-castinge.g. housings, covers, holders

8

CuFe2P

Copper-irone.g. bus bars, lead frames

9FeSi3

Electrical steel

e.g. stators, rotors, transformers

10

X10CrNi18-8

Spring steel

e.g. springs

11

MnZn-oxide

Ferritee.g. magnetic core, chokes, transformers(Table 28 List of materials used: fig. 93/94; source: https://www.zvei.org/fileadmin/user_upload/Presse_und_Medien/Publikationen/2020/Februar/ZVEI_Technische-Sauberkeit-in-der-Elektrotechnik_dt_engl/ZVEI_Guideline_Technical-Cleanliness-in-Electrical-Engineering_second-edition_Version-2020.pdf)

The quality solution: technical cleanliness.

> 200 µm or more present a potential risk of electrical short

But what is technical cleanliness?

circuit. If the metallic particles are of a certain length, angle
and position, and they land on the PCB in a particular way,

Technical cleanliness is a two-stage procedure that uses a lightthey can cause a short circuit. This is what makes it important

microscope to examine the number and size of particles present,

to find these critical particles and detach them from the PCBs.

followed by an electron microscope to confirm the chemical

Since there is no such thing as total cleanliness or purity,composition and origin of the particles. It therefore seeks tothen the focus should be on the most practically feasible andeliminate system failures that could potentially be caused byeconomically viable solution for the designated location andthese particles. The necessary level of technical cleanlinesspurpose. Particle contamination has been a growing problem

is determined on the basis of the particle-sensitive points onfor the automotive industry since the early 1990s, when systems

the system in question. The relevant particles may also differ

started becoming increasingly complex and installation spaces

in character – while combustion engines typically encounterever smaller. VDA 19/ISO 16232 was therefore established as a

hard and abrasive metallic particles, electronic engines can be

standard for enabling customers and suppliers to address thesusceptible to low- and high-conductivity particles.

risk of potential damage of products across the production
chain.

Most particles are generated during the processing ofcomponents and assemblies (approx. 80%) and only a fraction

In the electronics industry, VDA 19 does not specify any limiting(approx. 20%) are due to environmental influences. Since

values for component cleanliness. These must be definedmanufacturers cannot address every possible malfunction andaccording to component function, producibility, and verifiability.

manufacturing process, the aim here is to focus on metallic
particles.

When residual contamination is sufficiently low, the system is

When it comes to PCBs, any metallic particles that measureconsidered adequately clean.
4ZEISS Technical Cleanliness Solutions
Example workflow for semiconductors in cars

Extraction of particles from the component:

Determination of particles with light microscopes

Not a trivial process
The filter is placed under the light microscope (e.g. Axio Imager
Particles are removed from electronic circuit boards via a blowing

2, Axio Zoom.V16) in order to detect all the non-metallic andprocess. Since the electronic circuit boards can be damaged bymetallic shiny particles on the filter.

water, this cleaning process is performed with air – with a jetof clean and oil-free compressed air from a spraying tool andbonded to the wetted chamber wall. This process takes place in abox equipped with a pressure vent to prevent overpressure.
After being rinsed off the wetted chamber with a fluidthat subsequently flows through a filter, the particles are
duly captured in this filter and ready for analysis under themicroscope.

In the ZEISS ZEN Technical Cleanliness Analysis software, all suchparticles are listed in a table and categorized accordingly. Thanks
to the intuitive user interface, as well as the guidance provided tothe user throughout the application and in the workflow, you do
not need to be an expert in microscopes or software operation.
The support by defined microscope hardware and softwaresettings makes complex analysis processes both much easierto perform and more reliable. Data is stored by the system andexported if necessary, with the software also able to generate
a report according to the relevant standards. ZEISS ZEN core
Shuttle and Find also connects this data to electron microscopy
solutions, generating a seamless workflow for switching between
these technologies.
As the software enables the direct retrieval of highlighted
particles from a light microscope to an electron microscope, thisfurther boosts productivity and efficiency by providing immediate
access to the dedicated analysis view in the high-resolution
Light microscopes

electron microscope.

ZEISS SteREO Discovery.V8

ZEISS Axioscope 7

ZEISS Axio Zoom.V16

ZEISS Axio Imager 2

Particle size ≥ 15 µm
Standard analyses

Particle size ≥ 50 µm
Standard analyses

Particle size ≥ 5 µm
Advanced analyses

Particle size ≥ 1 µm
Advanced analyses
5Understand the root cause of particle contaminationmaterial, how it is built up, and where it is coming from (e.g.

with electron microscopes

forging process or supplier) – after all, the chemical compositionof the particles is determined by EDS measurement in order to

In order to find out more about the particles, filter is placed indetermine their origin.

an electron microscope such as ZEISS EVO or ZEISS Sigma. OurZEISS SmartPI provides much more than size, shape, distribution

connected system makes it easy to find the individual particles

and corresponding particle morphology, it also provides chemicalwith the support of ZEISS SmartPI SEM software. The use of acomposition and material characterization, thereby enabling theuniform portfolio uniquely enables us to save the coordinatesuser to locate the root cause of contamination.

of a critical particle and therefore identify the particle typeZEISS SmartPI can also design and create individual reports

with the ZEISS SmartPI software. The system then analyses thespecific to customer needs.

Electron Microscopywith EDSZEISS SmartPI
Quantification & advanced classification

HARDWARE

SOFTWARE

Run-upCalibrate

MoveCapture

Reporting
SmartPI Reporter

DetectMeasureAnalyze

ReportWorkflow overview
Component / test object

Extraction

Ultrasonictechniques

Pressure rinsing

Internal rinsing

Shake

Filtration

Analysis

Gravimetricanalysis

Light microscopy

SEM/EDS

Liquid particle
counter

Component / test object
6

Services from ZEISS AG

Technical cleanliness is rapidly growing in importance within the automotive
industry. At ZEISS, we help professionals understand our systems and bring themcloser to the handling of our machines.
We provide assistance for everything from construction, service, and repair to employee training
on correct use of the equipment. We are always available and at your side every step of the way.
Our Demo Center is fully equipped to prepare you for every aspect of our machines.

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

Carl Zeiss Industrial Metrology, LLC
6250 Sycamore Lane North
Maple Grove, MN 55369/USA

Vertrieb
Telefon: +49 7364 20 6336
E-Mail: sales.metrology.de@zeiss.com

Phone: +1 800 327-9735
Fax: +1 763 533-0219
info.metrology.us@zeiss.com

ServiceTelefon: +49 7364 20 6337
E-Mail: info.metrology.de@zeiss.com

www.zeiss.com/metrology

EN_60_010_0043I Created in Germany CZ-VI/2021
Subject to change in design and scope of delivery and as a result of ongoing technical development.

Source:https://www.zvei.org/fileadmin/user_upload/Presse_und_Medien/Publikationen/2020/Februar/ZVEI_TechnischeSauberkeit-in-der-Elektrotechnik_dt_engl/ZVEI_Guideline_Technical-Cleanliness-in-Electrical-Engineering_secondedition_Version-2020.pdf

www.zeiss.de/imt7