Glass Panel Surface Treatment by
Atmospheric Microplasma
Kazuo Shimizu, Akira Umeda and Marius Blajan
Innovation and Joint Research Center, Shizuoka University,
3-5-1 Jyouhoku, Hamamatsu, 432-8561, JAPAN; E-mail：blajanmarius@yahoo.com

Introduction

Experimental Setup(1)Microplasma Electrodes

Experimental setup for surface treatment.

(4) Electrical Characteristics
Very small discharge gaps and relatively low
discharge voltages (about 1 kV)⇨A high intensity electric field (107-108 V/m)assures the formation of microplasma and acorresponding discharge current.

The electrodes consist in perforated metallic
plates covered with a dielectric layer.
(a)Waveform of the discharge voltage, discharge
current and emission signal of microplasma
discharge in 1% N2 in Ar and in N2.

(b)Waveforms of the discharge voltage, corresponding
discharge current and gate signal for ICCD camera:(a) Marx Generator; (b) Neon transformer.

Emission Spectroscopy
Emission spectrum was measured
camera shutter opened for 1 µs.

Electrode size was 20 mm versus 40 mm foremission spectroscopy analysis. Discharge gap
was set at 50 μm in this study.
Microplasma electrodes for surface treatment
have 40 mm diameter .

(2) Power Supplies

16000
14000

(a)

Ar I

Ar I

12000
10000

Ar I

8000
6000

Ar I

Ar I

0410

415420425430435440

Wavelength (nm)Ar
1% N2 in Ar

16000
14000

Intensity (a.u.)

0.5% N2 in Ar
Ar
N240
30
20
10018000+V

A neon transformer was used to energize theelectrodes at 800 V in Ar and 1.5 kV in N2.
With the increase of treatment time thecontact
angle
isdecreasing
from45.6°without treatment to 5.5°after 180
seconds for the treatment with Ar.
5040002000Marx Generator with MOSFET switches:•Output Voltage: -2 kV negative•Rise time: 100 ns•Pulse width: 1 µs
•Frequency: 1-24 kHz
Neon transformer•Output voltage: up to 2 kV AC•Frequency 24 kHz

Surface Treatment of Glasswith18000

Intensity (a.u.)

Microplasma electrodes

Lifetime emission signal of N2 SPS peak at337.1 nm increased from 60 ns to about 500
ns when 1% N2 was added in Ar.
vibrational temperature was Tvib=3160 K.
Electron temperature was Te = 23000 K.
rotational temperature Tgas = Trot = 300 K⇨Microplasma=Nonthermal plasma

Contact angle (deg.)

Microplasma
canbefoundinmanyapplications. In the last years, the technology
was used in applications such as NOx removal,surface
treatment
andsterilizationorinactivationofbacteria.
Emission
spectroscopy is one of the methods to analyze
plasma process . The aim of this research istoanalyze
microplasma
byemission
spectroscopy for the process of glass surface
treatment. Other research groups investigatednonthermal plasma for surface treatment withsimilar characteristics such as high electron,and low rotational temperatures which
recommends microplasma as a solution for thesurface treatment of glass panels used inelectronic industry. Moreover the surface
potential after the microplasma treatment islow (about 20 V) comparing with plasma jetthat charges the surface at more than 200 V.

N2 molecules excited argon neutrals andreaction in argon plasma with N2 addition:
Ar*+ N2(X1Σg+)v=0 → N2(C3πu)v’=0 + Ar
Spontaneous radiation of formed excitedstate of nitrogen:N2(C3πu)v’=0 → N2(B3πg)v’’=0 + hνOH(b)02040

N2 SPS6080100 120 140 160 180Treatment time (sec.)

12000

Contact angle of a water droplet at the surface ofglass versus treatment time by microplasma
discharge in Ar, N2 and 0.5 % N2 in Ar.

10000
8000
6000

N2 SPS

4000

Trigger

Before treatment

2000

After treatment

0304

306

308

Vout

Experimental setup for emission spectroscopy.

Ar I

aa

Intensity (a.u.)

16000
14000

A microplasma enclosed reactor was used forsurface treatment of glass. A contact angle
meter was used to measure the contact angleof a water droplet at the surface of glass.
Gas flow rate: Ar and N2/Ar at 5 L/min.

31431631818000(3) Experimental setup
measured bycamera and312

Wavelength (nm)Photo of negative pulse Marx Generator.

Emission spectrum wasspectrometer, an ICCD
photomultiplier tube.

310

(c)

Ar I

12000
10000

Ar I

Conclusions

8000
6000
4000
2000

Ar I

0725

735

Contact angle of a water droplet at the surface ofglass before and after microplasma treatment..

745

755

765

Wavelength (nm)Emission spectrum of microplasma in: (a) Ar;(b) N2/Ar; (c) Ar at -1.2 kV.
Emission spectrum in Ar and Ar/N2 shows:•N2 second positive band system peaks at
315.9, 337.1, 357.7, 380.4, 400 and 405 nm.
•N2+ first negative band system peak at
391.4 nm.
•OH peaks at 306.4, 307.8 and 308.9 nm.
•Ar I peaks were measured at 415.8, 419.1,419.8, 420.1, 426.6, 427.2, 425.9, 433.3,696.5, 706.7, 727.3, 738.3; 703.2, 750.4 and772.4 nm.

•Emission spectrum of microplasma shown
intensity peaks of N2 SPS and N2+ FNS, OHand ArI.
•Lifetime emission signal peak of the 337.1
nm N2 SPS peak for microplasma in N2 was
60 ns and about 500 ns when 1% N2 wasadded in Ar.
•Temperatures of microplasma: Trot = 300 K;
Tvib = 3160 K; Te = 23000 K  thistechnology could be applied for the surface
modification due to its low gas temperatureand molecular excitation ability obtained atabout 1 kV.
•The contact angle of a water droplet at asurface of the glass panel decreased after
microplasma
treatment
from
45.6°to5.5°after 180 seconds for the discharge atonly 800 V in Ar. Contact angle wasdecreased at 12.4°after 180 seconds oftreatment at 1.5 kV in N2.