How does Parylene exhibit isolation properties and chemical resistance
1. Isolation performance
Parylene is thinner than other coatings and provides a pore free homogeneous barrier to prevent corrosion from liquids, moisture, chemicals, and common gases.
| Coating thickness (μ m) | Ca2+(ppm) | A13+(ppm) | Zn2+(ppm) |
| 0 | 0.16 | 5 | 46 |
| 0.1 | 0.13 | 1.5 | 32 |
| 0.5 | 0.02 | 0.1 | 10 |
| 1 | <0.003 | <0.05 | 0.1 |
| 2 | <0.003 | <0.05 | <0.05 |
Figure 1: Relationship between ion penetration and coating thickness
The isolation properties of Parylene. Compare the water vapor permeability with other coating materials again. The performance of Parylene C almost exceeds that of all other polymer materials. The water vapor permeability value is measured at thicknesses below 0.1 micrometers. After normalization of equal thickness, this value is the same for all thicknesses.
| Gas Permeability at 25 ℃(cc· mm/m²·d· atm) | Water Vapor Transmission (g⋅mil/100in²⋅d) | |||||||
| H₂ | N₂ | O₂ | C0₂ | SO₂ | H₂S | Cl₂ | ||
| Parylene N | 530 | 7.36 | 38 | 210 | 1800 | 760 | 72 | 1.35 |
| Parylene C | 100 | 0.9 | 7 | 7.2 | 10 | 12 | 0.2 | 0.18 |
| Parylen e F4 | – | – | – | – | – | – | = | 0.69 |
| Parylen e F8 | 253.1 | 4.8 | 23.5 | 95.4 | – | 0.51 | ||
| ER | 100 | 4 | 5-10 | 12 | = | 6.6 | ||
| SR | 46000 | – | 52000 | 8 | 220 | |||
| UR | – | 90 | 220 | 3200 | – | 20.2 | ||
| AR | – | 160 | 746 | 1500 | – | – | 27.8 | |
Figure 2: Different breathability and water vapor properties of coatings
2.Chemical resistance
The thickness change of 5-1.5mil film after immersion in various solvents for 90 minutes at room temperature (measured by infrared method). At room temperature, Parylene can resist the invasion of chemical substances and is insoluble in all organic solvents at 150 ℃. Parylene C can dissolve in chlorine at 175 ℃, while Parylene N is soluble at the melting point of the solvent (265 ℃). Both types of polymers can resist the invasion of most solvents. Meanwhile, they are not affected by stress cracking solvents such as Hostepal, Igepal, and lemon oil.
| solvent | Parylene Coating thickness variation | |
| C | N | |
| isopropyl alcohol | 0.3 | 0.2 |
| deionized water | 0 | 0 |
| isooctane | 0.3 | 0.2 |
| pyridine | 0.6 | 0.2 |
| Mixed Xylene | 2.2 | 1.5 |
| Trichloroethylene TCE | 0.9 | 0.5 |
| chlorobenzene | 1.4 | 1 |
| dichlorobenzene | 2.9 | 0.2 |
| Trichlorotrifluoroethane | 0.2 | 0.2 |
| acetone | 0.8 | 0.3 |
| 2,4-Pentanedione | 1.3 | 0.5 |
Figure 3: Solvent resistance of coatings
reagent |
concentration |
Parylen e Thickness variation (%) |
|
Parylen e N |
Pary1en e C |
||
hydrochloric acid |
10% |
0 |
0 |
concentrated hydrochloric acid |
37% |
0.2 |
0 |
sulfuric acid |
10% |
0.1 |
0.3 |
concentrated sulfuric acid |
95-98% |
0.2 |
0.4 |
nitric acid |
10% |
0.1 |
0.1 |
concentrated nitric acid |
71% |
0.2 |
0.2 |
chromic acid |
10% |
0.1 |
0.1 |
Concentrated chromic acid |
74% |
0.3 |
0 |
Strong alkali (sodium hydroxide) |
10% |
0.1 |
0 |
Weak base (ammonia hydroxide) |
10% |
0.3 |
0.2 |
