IEC 62047-15:2015

IEC 62047-15


®


Edition 1.0 2015-03



INTERNATIONAL



STANDARD



NORME
INTERNATIONALE
colour
inside


Semiconductor devices – Micro-electromechanical devices –
Part 15: Test method of bonding strength between PDMS and glass

Dispositifs à semiconducteurs – Dispositifs microélectromécaniques –
Partie 15: Méthode d'essai de la résistance de collage entre PDMS et verre


IEC 62047-15:2015-03(en-fr)

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IEC 62047-15



®



Edition 1.0 2015-03







INTERNATIONAL





STANDARD







NORME



INTERNATIONALE
colour

inside










Semiconductor devices – Micro-electromechanical devices –

Part 15: Test method of bonding strength between PDMS and glass




Dispositifs à semiconducteurs – Dispositifs microélectromécaniques –

Partie 15: Méthode d'essai de la résistance de collage entre PDMS et verre

















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 31.080.99 ISBN 978-2-8322-2291-1



Warning! Make sure that you obtained this publication from an authorized distributor.

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® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – IEC 62047-15:2015 © IEC 2015


CONTENTS



FOREWORD . 3

1 Scope . 5

2 Normative references . 5


3 Terms and definitions . 5

4 Testing method . 6

4.1 Visual test . 6

4.1.1 General . 6
4.1.2 Equipment . 6
4.1.3 Procedure . 6
4.1.4 Visual test results . 6
4.2 Bonding strength test . 6
4.2.1 General . 6
4.2.2 Sample preparation . 7
4.2.3 Procedure . 7
4.2.4 Result of blister test . 8
4.3 Contact angle measurement . 8
4.3.1 General . 8
4.3.2 Equipment . 8
4.3.3 Procedure . 8
4.3.4 Result of test . 9
4.4 Hermeticity test . 9
4.4.1 General . 9
4.4.2 Equipment . 9
4.4.3 Procedure . 10
4.4.4 Result of test . 10
Bibliography . 11

Figure 1 – Blister mask . 7
Figure 2 – PDMS blister . 8
Figure 3 – Contact angle measurement of water drop on PDMS . 9
Figure 4 – Test set-up for hermeticity . 10


Table 1 − Result of visual test . 6

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IEC 62047-15:2015 © IEC 2015 – 3 –



INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________




SEMICONDUCTOR DEVICES –

MICRO-ELECTROMECHANICAL DEVICES –



Part 15: Test method of bonding

strength between PDMS and glass


FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62047-15 has been prepared by subcommittee 47F: Micro-
electromechanical systems, of IEC technical committee 47: Semiconductor devices.
The text of this standard is based on the following documents:
FDIS Report on voting
47F/208/FDIS 47F/213/RVD

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

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– 4 – IEC 62047-15:2015 © IEC 2015


A list of all parts in the IEC 62047 series, published under the general title Semiconductor

devices – Micro-electromechanical devices, can be found on the IEC website.


The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be


• reconfirmed,

• withdrawn,

• replaced by a revised edition, or


• amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.

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IEC 62047-15:2015 © IEC 2015 – 5 –


SEMICONDUCTOR DEVICES –

MICRO-ELECTROMECHANICAL DEVICES –



Part 15: Test method of bonding strength between PDMS and glass








1 Scope


This part of IEC 62047 describes test method for bonding strength between poly dimethyl
siloxane (PDMS) and glass. Silicone-based rubber, PDMS, is used for building of chip-based
microfluidic devices fabricated using lithography and replica moulding processes. The
problem of bonding strength is mainly for high pressure applications as in the case of certain
peristaltic pump designs where an off chip compressed air supply is used to drive the fluids in
micro channels created by a twin layer, one formed by bondage between glass with replica
moulded PDMS and another between PDMS and PDMS. Also, in case of systems having
pneumatic microvalves, a relatively high level of bonding particularly between two replica
moulded layers of PDMS becomes quite necessary. Usually there is a leakage and debonding
phenomena between interface of bonded areas, which causes unstability and shortage of
lifetime for MEMS devices. This standard specifies general procedures on bonding test of
PDMS and glass chip.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 62047-9, Semiconductor devices – Micro-electromechanical devices – Part 9: Wafer to
wafer bonding strength measurement for MEMS
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
complete bonded area
bonded wafer without void areas
3.2
hydrophilic
physical property of a molecule that can bond with water (H O) through hydrogen bonding
2
Note 1 to entry: A definition of the term "molecule" can be found on this page:
http://en.wikipedia.org/wiki/Molecule.
Note 2 to entry: A definition of "hydrogen bond" can be found on this page:
http://en.wikipedia.org/wiki/Hydrogen_bonding.
3.3
hydrophobic
property that tend to be non-polar molecules which form aggregates of like molecules in water
and analogous intramolecular interactions

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– 6 – IEC 62047-15:2015 © IEC 2015


3.4

PDMS

silicone-based rubber poly dimethyl siloxane having a chemical formula of

(H C) SiO[Si(CH ) O] Si(CH )
3 3 3 2 n 3 3


4 Testing method


4.1 Visual test

4.1.1 General


The visual test should be performed to confirm whether substantial other bonding tests are
required. Visual test is a simple qualitative test method.
Optical equipment shall be used to evaluate the bonding interface of glass to PDMS and
PDMS to PDMS.
4.1.2 Equipment
One or a few equipments of optical microscope, scanning acoustic microscope, scanning
electron microscope (SEM), transmittion electron microscope (TEM) and infra-red (IR) or
optical camera can be used.
4.1.3 Procedure
The procedure is as follows:
a) to observe bonding conditions using the optical microscope;
b) to measure voids areas and bubbles using images observed images by optical microscope
and IR camera.
4.1.4 Visual test results
The test results can be classified into three classes after observation based on the Key in
Table 1 for each.
Table 1 − Result of visual test
Type numbers or serial numbers of objective wafer Good Fair Poor
1
2

3
Key
Good – complete bonded area larger than 95 %
Fair – complete bonded area larger than 75 %
Poor – complete bonded area larger than 50 %

4.2 Bonding strength test
4.2.1 General
The bond strength is measured using the blister test wherein a blister of 3 mm diameter is
made in PDMS using photolithography and replica moulding techniques. General
requirements are given in IEC 62047-9.

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IEC 62047-15:2015 © IEC 2015 – 7 –


4.2.2 Sample preparation


The masks for selective patterning are designed and printed by using a high-resolution printer

(see Figure 1).








10 mm
IEC

Figure 1 – Blister mask
The fabrication of the blister is done in two layers. The negative photoresist is spun onto a
cleaned glass wafer of 63,5 mm diameter.
The typical thickness of the resist is about 200 µm after spinning. The negative photoresist is
next patterned using the mask as shown in Figure 1. This negative is used to cast the PDMS
up to 2,5 mm thickness.
After curing the PDMS cast, pieces of size 12,7 mm × 12,7 mm are cut around the blister
shapes. These are then bonded to pieces of plain PDMS, or cleaned glass slides of similar

size by plasma treatment. For glass/PDMS bonding, the glass slides are thoroughly cleaned
by boiling in piranha solution (5:1 ratio of concentrated and 30% solution) for 3 min to 4 min
and then, repeatedly washed in DI water before plasma exposure.
4.2.3 Procedure
After fabricating the blister, an input port is attached to it using a steel pipe and a polyether
ether ketone (PEEK) tubing, which is epoxied to one of the edges (see Figure 2). A regulated
nitrogen or air supply is connected to the device.

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1 2 3 4








5



IEC
Key
1 PEEK tubing 2 Epoxy
3 Steel tube 4 Blister
5 Compressed nitrogen or air to expand the blister
Figure 2 – PDMS blister
4.2.4 Result of blister test
The pressure at which the blister starts to fail is noted down. The pressure is proportional to
the bonding strength.
4.3 Contact angle measurement
4.3.1 General
Contact angle measurement is the ideal method to characterize surface wettability and widely
used technique of loss and recovery of hydrophobicity of silicone rubbers. So, this method
can be used to accurately measure the hydrophilic characteristic of a surface for a polymer
like PDMS, whose surface properties change speedily with post exposure time.
4.3.2 Equipment
A camera of the contact angle setup should be used. Simultaneously, a separate set of Glass-
PDMS and PDMS-PDMS substrates exposed in the same run of the exposure tool are brought

into conformal position with each other after a similar span of time
...