Characterization of UV Curing PolymersCharacterization of UV Curing Polymersby Photochemical Reaction DSC Systemby Photochemical Reaction DSC System

Ultraviolet curing polymers are used in wide number of fields such as general electronics, optical electronics, medical fields, glass arts, and architecture. Curing reaction heat when the UV is irradiated can be measured real-time by using Photochemical Reaction DSC System.

In this study, the analysis result of Photoresist and UV curing adhesive is reported as an analytical example using Photochemical Reaction DSC System. The UV irradiation condition dependence of wavelength, irradiation intensity, or temperature against exothermic reaction heat, rate of reaction, or reaction time during UV irradiation is observed.

▌ Introduction

Nobuaki Okubo1, Alexander Rumyantsev2

1 SII NanoTechnology Inc., 2 Labtest

▌ Experiment

▌ Results

Sample 2: UV Curing AdhesiveUV Curing AdhesiveThe sample is a single-component anaerobic 10-second curing type UV curing adhesive.

Sample 1: PhotoresistPhotoresistDry film of Photoresist is composed several components, including an acrylic monomer that hardens through a polymerization, a binder polymer to form the film, a light-curing initiator and other additives.

Materials

InstrumentsHigh Sensitivity Differential Scanning CalorimeterDSC7020UV Irradiation Unitfor Photochemical Reaction DSC Measurement

PDC-7SII NanoTechnology Inc.

Photoresist provides high resolution and can be used in microfabrication. Furthermore, it can be used to form etching-resistant thin-film in a short period of time. Due to these features, it is used in a wide number of areas, including printed circuit board wiring, electronic parts manufacturing and print plate-making. However, it is known that conditions during light curing, including exposure wavelength, irradiation intensity and reaction temperature, change the formation of etching-resistant thin-film. Therefore, it is necessary to consider various curing conditions when attempting to form the optimal etch-resistant thin-film.

PhotoresistPhotoresistThe sample is the commercially available UV cure adhesive. Due to the fact it is good to adhere the plastics, it is used to fix and seal the LDC panel, the PCB, and the flexible wirings. In case of UV cure adhesive, a variety of parameters has to be explored to achieve the optimized adhesive quality.

UV Curing AdhesiveUV Curing Adhesive

0 1 2 3 4 5

3.0

2.0

1.0

0.0

DS

C (m

W)

Time (min)

50mW/cm2 ΔH = 75.0 J/g

10mW/cm2 ΔH = 69.9 J/g

5mW/cm2 ΔH = 67.0 J/g

1mW/cm2 ΔH = 59.8 J/g

Fig.2 DSC curves for dry film at different irradiation intensitiesIrradiation wavelength: 365 nmMeasurement temperature: 25 ℃

0 1 2 3

3.0

2.0

1.0

0.0

DS

C (m

W)

Time (min)

50mW/cm2

10mW/cm2

5mW/cm2

1mW/cm2

Sum

(%)

100

80

60

40

20

0

Fig.3 Integral curves of different irradiation intensitiesIrradiation wavelength: 365 nmMeasurement temperature: 25 ℃

0 1 2 3 4 5

2.0

1.0

0.5

0.0

DS

C (m

W)

Time (min)

1.5

2.5

365nm

405nm

436nm

313nm254nm

Fig.4 DSC curves for dry film at different irradiation wavelengthsIrradiation wavelength: 5 mW/cm2

Measurement temperature: 25 ℃

0 1 2 3

3.0

2.0

1.0

0.0

DS

C (m

W)

Time (min)

4.0

5.075℃

50℃

25℃

Fig.5 DSC curves for dry film at different measurement temperatureIrradiation wavelength: 365 nmIrradiation wavelength: 5 mW/cm2

0 0.5 1.5 2.0

60

40

20

0

DS

C (m

W)

Time (min)

500mW/cm2

100mW/cm2

10mW/cm2

1mW/cm2

80

20mW/cm2

2mW/cm2

Fig.6 DSC curves for UV Curing Adhesive at different irradiation intensitiesIrradiation wavelength: 365 nmMeasurement temperature: 30 ℃

Fig.7 DSC curves for UV Curing Adhesive after measurementsof Figure 5 by heating measurements

Sample weight: 2 mgHeating rate: 10 ℃/min

60 80 100 200

6

4

2

0

DS

C (m

W)

Temperature (℃)

118.7 ℃

120 140 160 180

174.3 ℃

113.6 ℃

114.4 ℃

173.9 ℃

173.9 ℃

174.2 ℃

174.8 ℃

175.2 ℃

-6

-4

-2

Unirradiated

500mW/cm2

100mW/cm2

10mW/cm2

1mW/cm2

2mW/cm2

DSC7020PDC-7

Fig.1 Spectral distribution for UV Spot Light SourceReflector: 254nm type Lamp: Hg – Xe Lamp (Quartz type)Light guide: Quartz Fiber φ5, 1m type

25th European Symposium on Applied Thermodynamics @ Saint Petersburg, Russia