IEC 62899-302-6:2025

IEC 62899-302-6 ®
Edition 1.0 2025-05
INTERNATIONAL
STANDARD
Printed electronics –
Part 302-6: Equipment – Inkjet – First drop measurement
ICS 19.080; 37.100.10 ISBN 978-2-8327-0414-1

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– 2 – IEC 62899-302-6:2025 © IEC 2025
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 7
2 Normative references . 7
3 Terms, definitions and abbreviated terms . 7
3.1 Terms and definitions . 7
3.2 Abbreviated terms. 8
4 Inkjet first drop measurement . 8
4.1 General . 8
4.2 Process for printing-based method . 8
4.3 Process for high speed camera imaging-based method . 9
4.4 Process for single flash imaging based method . 10
5 Recorded operating parameters for drop speed measurements . 11
Annex A (normative) Key considerations for inkjet first drop measurement . 12
A.1 Printing measurement . 12
A.2 High speed camera based measurement . 15
A.2.1 General. 15
A.2.2 Measurement steps using high speed camera . 16
A.2.3 Analysis method of acquired images . 18
A.2.4 Jetting speed measurement for first drop analysis . 20
A.3 First drop measurement using imaging device (CCD camera) with flash light
source . 22
Bibliography . 24

Figure A.1 – Typical first drop effect . 12
Figure A.2 – Jetting speed effects on drop placement . 13
Figure A.3 – Patterns for first drop evaluation . 14
Figure A.4 – Practical guidelines to obtain acceptable printing accuracy . 15
Figure A.5 – Vision measurement based on high speed camera . 16
Figure A.6 – Trigger based image acquisition and jetting for first drop measurement. . 17
Figure A.7 – Non-jetting pause time effects on the first drop jetting speed . 18
Figure A.8 – Sorted drop images (ink type A) . 19
Figure A.9 – Sorted drop images (ink type B) . 19
Figure A.10 – Two jetting images of a droplet, to calculate jetting speed . 20
Figure A.11 – Jetting speed calculation from the droplet locations at two timings . 21
Figure A.12 – Jetting speed behaviour according to non-jetting time . 21
Figure A.13 – Timing chart for CCD camera based measurement . 23

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PRINTED ELECTRONICS –
Part 302­6: Equipment – Inkjet – First drop measurement

FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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shall not be held responsible for identifying any or all such patent rights.
IEC 62899-302-6 has been prepared by IEC technical committee 119: Printed Electronics. It is
an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
119/534/FDIS 119/543/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.

– 4 – IEC 62899-302-6:2025 © IEC 2025
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 62899 series, published under the general title Printed electronics,
can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
INTRODUCTION
Drop-on-demand inkjet printing has been used as a manufacturing tool for printed electronics.
The use of inkjet has many advantages since an exact amount of droplets can be deposited on
target locations without wasting excessive amount of materials. To position the inkjet head on
the printing location, jetting from the inkjet head should be paused for a while. As a result, it
has been well known that the initial first few drops, after the non-jetting pause time, can be
different from that of the steady state jetting. The abnormal behaviours of the first few drops
can cause serious printing quality problems. Also, it could produce poor yield when used in
manufacturing process. So, the proper evaluation of first-drop failures has been important steps
for inkjet process development.
Moreover, substrates can be unloaded and loaded for printing, especially in printed electronics
applications. By using a fiducial camera to view the substrate, the printing target position in the
substrate is identified via alignment marks on substrates. Also, the substrate should be aligned
with respect to motion stage axes prior to printing. It can take considerable time and the jetting
should not occur during the preparation for printing. Due to the non-jetting period, ink on the
nozzle surface can dry, and consequently the jetting behaviours of the first few drops are likely
to differ from those of steady-state jetting. If the abnormal jetting behaviour is significant,
printing quality can be affected accordingly. As a result, a proper measurement method should
be developed to evaluate the jetting failure.
The main cause of the first drop behaviour including low jetting speed and non-jetting status
can be from the ink drying on nozzle substrates. However, apart from the ink solidification on
substrate, it can be affected by jetting frequency. The piezo type inkjet head uses pressure
waves generated inside of the head. The first drop is not affected by the residual pressure
waves from the previous drops. However, from the second drops, the jetting can be affected by
residual pressure waves from the previous jetting. Also, pressure wave amplification is different
according to jet frequency due to residual pressure. Thus, the first drop behaviour might be
affected. This document provides the measurement and analysis method for first drop
dissimilarity but does not provide the method to decide the cause of the non-similarity of first
drops. Nonetheless, by engineering judgement, the causes of first drop dissimilarity can easily
be determined.
In order to measure inkjet behaviour, the methods using drop visualization systems based on a
light emitting diode (LED) have been standardized. The methods are useful because real-time
monitoring is possible by using a charge-coupled device (CCD) camera. However, the method
has difficulty and limitations in measuring the transient jet behaviour of the first few drops
because it uses a low-frame rate (~30 frame/s) CCD camera. Nevertheless, the conventional
hardware for drop visualization system can be used for first drop measurement by modifying
the measurement methods.
In this document, the measurement method and guidelines will be presented including the
method using a CCD camera illuminated by pulsed light. Other methods are also presented
including the methods based on high speed camera as well as printing system. Most printing
systems are capable of inspecting printed dots right after printing. Printed patterns can be
effectively used for evaluation of first few drops in relations to various parameters.
On the other hand, the price of high speed camera is becoming cheaper and the performance
is improving. The hardware requirement and synchronization method is relative simple when
the high speed camera is used for measurement. In addition, the method using high speed
camera does not require an expensive printing system and first drop effects can be effectively
analysed.
– 6 – IEC 62899-302-6:2025 © IEC 2025
Each method has merits and limitations and this document does not recommend specific
methods.
The evaluated first drop behaviour can be used for ink development to improve jetting quality.
Also, it can be used for process development such as pre-spitting (or pre-jetting) method and
head control method (for example, meniscus excitation method).

PRINTED ELECTRONICS –
Part 302­6: Equipment – Inkjet – First drop measurement

1 Scope
This part of IEC 62899 specifies the method for determining inkjet first drop behaviour based
on either visualized droplet images or printed dots on standard substrate. The exact behaviour
that is referenced in this document is as follows: jetting speed variation according to the drop
numbers, including non-jetting and low jetting speed. This measurement standardization is
limited to drop-on-demand type of inkjet including piezo and thermal types and is not applicable
to continuous inkjet. This document includes the test equipment, printing procedures, and
analysis of drop behaviour. This document is limited to printed electronics application and is
not suitable for graphic or other applications.
2 Normative references
There are no normative references in this document.
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1.1
inkjet first drop
jetted drop dissimilar behaviour of first few drops after non-jetting period of time
3.1.2
pre­jetting
pre­spitting
idle jetting of inkjet to help recover normal jetting status after slight non-steady state jetting
3.1.3
pre­printing
idle jetting, which is performed on substrate region
3.1.4
non­jetting time
pause time
waiting time between the normal jetting status and the next trigger for inkjet jetting

– 8 – IEC 62899-302-6:2025 © IEC 2025
3.1.5
inkjet maintenance
procedures such as purging (using pressure), wiping the nozzle surface and other procedures
used to help recover normal jetting status when pre-spitting (or pre-jetting) cannot maintain the
jettability
3.2 Abbreviated terms
CCD charge-coupled device
LED light emitting diode
4 Inkjet first drop measurement
4.1 General
Clause 4 describes the measurement methods for first drop dissimilarity, which can be divided
into printing-based methods and imaging-based methods. Here, two imaging methods are
discussed: one using a high-speed camera and the other using a CCD camera.
Printing-based methods are simple and effective for understanding the behaviour of the first
drops. Printed patterns can be used effectively to evaluate the first few drops in relation to
various parameters.
The price of high-speed cameras is decreasing, and their performance is improving. The
hardware requirements and synchronization methods are relatively simple when using a high-
speed camera for measurement. Additionally, this method does not require an expensive
printing system, and first drop effects can be effectively analysed. However, it is not preferred
to use high-speed cameras for drop visualization in most printing systems.
Alternatively, a strobe LED-based visualization system using a CCD camera is often employed.
The lighting and image analysis methods differ from those described in previous standards [5] ,
[6].
Each method has its merits and limitations, and this document does not recommend any specific
method.
NOTE The CCD camera is a representative device among imaging devices with a relatively low frame rate (normally,
approximately 30 frames per second). Other similar imaging devices, such as CMOS cameras, can also be used for
strobe LED-based visualization.
4.2 Process for printing­based method
The printing method is a simple method to implement in any printing systems.
1) Specify the printing conditions. In the printing-based method, there are the pre-jetting (or
maintenance) zone and printing zone. The time between the pre-spitting and printing should
be adjustable via either a software or an operator. All the parameters such as pre-spitting
number of dots, pausing time, test printing location and test patterns should be determined
in advance. It is important that the pattern printing region should not include the acceleration
region so that the dot spacing should not be affected by acceleration of motion speed. The
reference patterns are described in Clause A.1, which is recommended unless otherwise
specified. Jetting frequency is also related to first drop behaviour. High frequency jetting
can cause first drop dissimilarity related to residual pressure waves. By changing the jetting
frequency effects, the residual pressure wave effects on first drop can be understood. The
details of the effects are described in Clause A.1. The jetting frequency can be estimated
(or determined) from the printing speed and dot spacing, D, along the main printing direction.
Here, the jet frequency can be calculated by
___________
Numbers in square brackets refer to the Bibliography.

V
p
(1)
F=
D
where
F is the jetting frequency, expressed in Hertz (Hz);
V
p
is the printing speed, expressed in metres per second (m/s);
D is the dot spacing along the printing direction expressed in metres (m). D should
consider the dot size of droplets deposited on substrates so that D should be
sufficiently larger than the diameter of the dot so that the drop can be separated;
V
p
is related to motion stage movement and it should be in the range of allowable motion
stage movement speed. Prepare the substrates for test printing. The required
substrates for dot inspection can be referenced from IEC 62899-302-4 [1].
2) Perform inkjet maintenance at the maintenance zone if necessary. In addition, perform
sufficient pre-spitting to ensure steady state jetting at the separately prepared maintenance
zone.
3) Move the head to the target location. Print the pre-determined patterns including the pre-
printing, pause for non-jetting time and then move to the location for the inspection pattern.
Print the inspection patterns. The requirements for inspection pattern and pre-printing are
described in Clause A.1.
4) Inspect the printed patterns along the printing direction. The printing location accuracy and
directionality of droplets are measured along the printing direction. The details for
measurement methods are described in Clause A.1
4.3 Process for high speed camera imaging­based method
This process describes the first drop dissimilarity measurement methods based on high-speed
imaging. The method includes the imaging system, image acquisition methods and analysis
methods. The detailed information is described in Clause A.2.
1) Specify the jetting frequency of interest. Other jetting conditions described in Clause 5
should be specified.
2) Specify the frame rate of the high-speed camera. For easier analysis, multiple integer times
(n) of the jetting frequency can be selected for the frame rate. If not specified, a frame rate
of 5 times to 10 times higher than the jet frequency is recommended. The recommended
drops will be in the range from 30 drops to 100 drops depending on the severity of the first
drop dissimilarity [7]. A total number of frames of 300 images to 1 000 images should be
taken if a ten times higher frame rate is used. The relationship will be written as:
Ff× n ( is an integer)
n
(2)
r jet
N nN×
frame jet (3)
where
F
r
and N are the frame rate of high-speed camera and the number of frames
frame
(images), respectively, and
f
jet
, n and N are the jet frequency, integer number and number of jet droplets,
jet
respectively.
=
=
– 10 – IEC 62899-302-6:2025 © IEC 2025
3) After setting all parameters, inkjet maintenance including purge can be performed if the
head is not returned to the normal jetting condition. After maintenance, pre-spitting of the
nozzle should be performed to ensure the steady-state jetting. After ensuring normal jetting,
the jetting is paused for a pre-setting time. During the pause time, jetting and high-speed
camera are in the standby status waiting for trigger.
4) Right after pausing, the jetting and high-speed camera are triggered at the same time. The
number of jettings (N ) should be sufficient so that the print head can reach the normal
jet
jetting conditions. The number of image frames should be multiple integers n times the
number of jettings. Perform image analysis so that the drop location of the same timing of
each droplet can be compared. The jetting speed can be estimated from the droplet travel
distance during a specific time. The details of image analysis are described in Clause A.2.
4.4 Process for single flash imaging based method
This process describes the first drop dissimilarity measurement methods based on droplet
images acquired by the CCD camera (low frame rate imaging devices). The detailed information
is described in Clause A.3.
1) Specify the jetting frequency of interest. Due to the limitation of the frame rate of the Imaging
devices, sufficiently low jetting frequency is preferred.
2) Set up the imaging devices acquisition parameters. When using the Imaging devices, the
single frame should be used with the camera triggering via the jetting signal. The exposure
time should be sufficient to measure the jetting behaviour but should be less than the inverse
of the frame rate. The snap image acquisition mode is preferred to continuous acquisition
using the grab mode in order to ensure single image acquisition per drop. Unlike the high
speed camera imaging, short light pulses should be used. More than one pulse light per
droplet can be used to measure the speed variation of the first drop.
3) After setting all parameters, the maintenance of the head including the purge can be
performed if the head is not returned to normal jetting condition. After maintenance,
sufficient spitting of the nozzle should be performed to ensure the steady-state jetting. After
ensuring normal jetting, the jetting is paused for a pre-setting time. During the pause time,
the jetting and the imaging devices are in the standby status waiting for the same trigger. In
addition, the short light pulse should be also waiting for the trigger. In case snap image
acquisition is used, each droplet trigger signal (used for generating droplets) should be used
for both triggering of the camera and pulse lights.
4) Immediately after pausing, the jettin
...