IEC 62899-302-2:2018

IEC 62899-302-2 ®
Edition 1.0 2018-05
INTERNATIONAL
STANDARD
Printed electronics –
Part 302-2: Equipment – Inkjet – Imaging-based measurement of droplet volume

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IEC 62899-302-2 ®
Edition 1.0 2018-05
INTERNATIONAL
STANDARD
Printed electronics –
Part 302-2: Equipment – Inkjet – Imaging-based measurement of droplet volume

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 19.080; 37.100.10 ISBN 978-2-8322-5671-8

– 2 – IEC 62899-302-2:2018 © IEC 2018
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Droplet volume measurement . 6
4.1 General . 6
4.1.1 Overview . 6
4.1.2 Volume measurement and droplet shape equalization processes . 6
4.1.3 Imaging optics . 7
4.1.4 Image shape processing . 7
4.1.5 Calibration . 7
4.1.6 Uncertainties . 7
4.2 Processes for measurement of inkjet droplet volume . 8
4.2.1 General . 8
4.2.2 Process for measurement of inkjet droplet volume – Method 1 . 8
4.2.3 Process for measurement of inkjet droplet volume – Method 2 . 8
Annex A (informative) Key considerations for in-flight droplet volume measurement . 10
A.1 Jetted droplet volume in printed electronics . 10
A.1.1 General . 10
A.1.2 Image resolution . 10
A.1.3 Greyscale-to-binary image conversion . 11
A.1.4 Absolute droplet volume . 13
A.2 Formulae for inkjet droplet volume . 14
A.3 Results . 15
Bibliography . 16

Figure 1 – Representation of greyscale drop size 1 (“native drop”) to size 7 . 5
Figure A.1 – Magnified droplet grey image . 10
Figure A.2 – Threshold value influence on binary image: on the left, a threshold of 25;
on the right, a threshold of 75 . 12
Figure A.3 – Apparent image height of objects imaged near the focal plane (FP) using
a conventional lens . 12
Figure A.4 – Example of percentage size distortion in image plane for a conventional lens . 13
Figure A.5 – Shadowgraph of inkjet-printed droplets, ligaments and satellites in-flight . 14

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PRINTED ELECTRONICS –
Part 302-2: Equipment – Inkjet –
Imaging-based measurement of droplet volume

FOREWORD
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62899-302-2 has been prepared by IEC technical committee 119:
Printed Electronics.
The text of this International Standard is based on the following documents:
FDIS Report on voting
119/204/FDIS 119/216/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – IEC 62899-302-2:2018 © IEC 2018
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 "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

PRINTED ELECTRONICS –
Part 302-2: Equipment – Inkjet –
Imaging-based measurement of droplet volume

1 Scope
This part of IEC 62899 specifies the method for determining accurate inkjet droplet volume
based on images obtained by drop-in-flight measurement systems. It does not apply to
imaging systems using interference fringes, such as holography or phase doppler
anemometry. This document is not limited to drop-on-demand inkjet systems, but might not be
applicable to continuous inkjet or liquid dispensing systems. This document includes a
description of the issues concerning such measurements and consideration of the limits to
measurement accuracy.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
droplet volume
amount of jetted fluid from an inkjet print-head nozzle measured by single event imaging
Note 1 to entry: For a single event drive pulse designed to produce sub-drops that are intended to merge in-flight
to form a larger droplet, for example to form a specific greyscale image value on deposition, droplet volume refers
to the large merged droplet and not to smaller component sub-drops.
3.2
native drop volume
amount of fluid within the smallest sub-drop jetted from a greyscale inkjet print-head used to
create images with droplets formed by multiple sub-drops within a single event
Note 1 to entry: Native drops (or threads or satellite drops) might be too small for accurate measurements by
flash imaging, but satellite drops that have merged in-flight might be large enough for drop analysis systems. (See
Figure 1 for a representation of the relative sizes for greyscale droplets in-flight.)
IEC
Figure 1 – Representation of greyscale drop size 1
(“native drop”) to size 7
– 6 – IEC 62899-302-2:2018 © IEC 2018
4 Droplet volume measurement
4.1 General
4.1.1 Overview
This document concerns accurate determination of inkjet droplet volume from high speed
flash images of inkjet droplets travelling in-flight from inkjet print-head nozzles. Accurate
relative (rather than absolute) droplet volumes are useful for industrial inkjet-printed
electronics applications. Short flash durations avoid significant motion blurring in droplet
images. Two widely used scenarios, for flash imaging as applied to measurement of inkjet
drop speed, are considered in this document b
...