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Parylene N of Parylene series materials

2021-07-10 来源:亚科官网

      1.Seven kinds of Parylene series materials

     At present, according to different molecular structures, Parylene materials can be divided into Parylene N, Parylene C, Parylene D, Parylene F, Parylene HT and other types. Parylene material is currently the best waterproof material for electronic components that has been used in large-scale commercial applications on the market. Among them, the raw materials of Parylene C and Parylene N are cheap and have the widest application range, but Parylene C and N have poor high temperature resistance and UV resistance, and their application effects are limited; Parylene HT is more efficient in preparation Low, very expensive, and small in scope of use; Parylene F has good high temperature resistance, UV resistance, lower dielectric constant, good wave transmission performance, and is widely used in high-end LED screen waterproof protection. Waterproof protection of PCB circuit motherboards of energy electric vehicles, coating of high-end medical equipment, etc.

       2.Introduction of Parylene N

       Parylene N has excellent dielectric properties, high breakdown strength, and parylene film has little or no change in dielectric constant and dielectric loss with the change of electrical frequency. It is the first coating film to realize industrial application. Parylene N is especially suitable for the coating of medical products and elastomers. During the deposition process, because parylene N has higher molecular activity than Parylene C, it can penetrate the gaps more effectively. In addition, parylene N has a higher dielectric strength, and the dielectric constant value does not depend on frequency. Since parylene N has higher molecular activity than parylene C, vacuum vapor deposition takes longer, resulting in higher coating costs than parylene C.

       3.Parylene N coating example 1

Choose 316L grade stainless steel as the substrate, and the coating steps are as follows:

(1) Adopt dipping method (solution: 0.5 vol% methacryloxypropyltrimethoxysilane dissolved in 50% water/50% isopropanol, immersion time: 30 minutes, drying treatment: high pressure argon at 65°C Dry under air for 30 minutes), cover a layer of silane coupling agent A174 on the surface of stainless steel metal;

      (2) Coating by CVD method through Para Tech Coating Scandinavia AB equipment. Parylene N dimer, as the precursor, decomposes into reactive monomers at 650℃, and then spontaneously deposits and polymerizes at room temperature.

       4.Parylene N film properties

Table 1. Thermal properties of parylen N

Melting point

420℃

T5 Point

(Modulus=690 Mpa)

160℃

T4 Point

(Modulus=70 Mpa)

>300℃

Continuous use temperature

60℃

Short-term use temperature

80℃

Coefficient of linear thermal expansion at 25℃

69 ppm

Thermal conductivity at 25°C

0.126 W/(m·K)

Specific heat capacity at 20℃

0.837 J/(g·K)


Table 2. The mechanical properties and barrier properties of parylene N

Mechanical properties

ASTM D882

Tensile modulus

3.2 Gpa

Yield strength

55 Mpa

tensile strength

70 Mpa

Elongation

2.9%

Elongation at break

20%-250%

Barrier performance

ASTM E96

Water vapor penetration(37℃,10μm)

30 g/m2·day

Table 3. Electrical properties of parylene N

Dielectric constant

ASTM D150

60Hz

2.65

1kHz

2.65

1MHz

2.65

Dielectric loss

ASTM D150

60Hz

0.0002

1kHz

0.0002

1MHz

0.0006

Dielectric strength

7000 V/mil

DC breakdown

10μm

~4000V

25μm

~7000V

Volume resistivity

(23℃,50%RH)

ASTM D257

1.4×1017Ω·cm

Surface resistivity

(23℃,50%RH)

ASTM D257

1.0×1013Ω

References:

Parylene coatings on stainless steel 316L surface for medical applications -Mechanical and protective properties,Materials Science and Engineering C,2011,doi:10.1016/j.msec.2011.09.007