Technical Information

Typical technical information and properties of dielectric material for
flexible printed circuitry.
Property Units Polyimide Polymide (Adhesiveless) Polyester
Representative Trade Name - Polyimide Polyimide Mylar
Physical
Thickness Range mil .5 to 5 1 – 6 0.025 to .5
Tensile Strength (at 25° C) psi 25,000 50,000 20,000 to 35,000
Break Elongation % 70 50 60 to 165
Tensile Modulus (at 25° C) Tensile Modulus (at 25° C) 4.3 .7 5
Tear Initiation Strength lb/in 1000 700 – 1200 1000 to 1500
Tear Propagation Strength g/mil 8 20 12 to 25
Chemical
Resistance to:
Strong Acids - Good Good Good
Strong Alkalis - Poor Good Poor
Grease and Oil - Good Good Good
Organic Solvents - Good Good Good
Water - Good Good Good
Sunlight - Fair Good Good
Fungus - Non-nutrient Non-nutrient Non-nutrient
Water Absorption (ASTM D570) % (24 hours) 2.9 .8 < 0.8
Thermal
Service Temperature (min/max) Coefficient of Thermal degree C -200/+300 -200/ +350 -60/+105
Expansion (at 22° C) PPM/ degree C 20 20 27
Change in Linear Dimensions (100° C, 30 min) % < 0.3 0.01 – 0.02 < 0.5
Electrical
Dielectric Constant (ASTM D150) 1MHz   3.4 3.4 3
Dissipation Factor (ASTM D150) 1MHz   0.01 .003 0.018
Dielectric Strength (ASTM D149) @ 5 mil thickness Volume Resistivity (ASTM D257) V/mil
ohm-cm
3800
1.0E+16
6000
1.0E+16
3400
1.0E+16
Current Carrying Capabilities:
Copper Weight
AMPS 1/2 oz.
(0.0007″)
1 oz.
(0.0014″)
2 oz.
(0.0028″)
3 oz. 4 oz. 5 oz. 6 oz. 7 oz.
Width in Inches
0.5 0.013″ 0.008″ N/A N/A N/A N/A N/A N/A
1.0 0.028″ 0.017″ 0.013″ N/A N/A N/A N/A N/A
1.5 0.040″ 0.027″ 0.020″ N/A N/A N/A N/A N/A
2.0 0.053″ 0.040″ 0.030″ 0.0235″ N/A N/A N/A N/A
2.5 0.080″ 0.060″ 0.042″ 0.0325″ 0.0285″ N/A N/A N/A
3.0 0.100″ 0.083″ 0.057″ 0.045″ 0.0387″ N/A N/A N/A
4.0 0.160″ 0.120″ 0.088″ 0.066″ 0.055″ 0.048″ 0.043″ N/A
5.0 0.225″ 0.158″ 0.118″ 0.09″ 0.074″ 0.065″ 0.059″ 0.053″
6.0 0.285″ (off chart) 0.195″ 0.153″ 0.117″ 0.094″ 0.082″ 0.074″ 0.0687″
7.0 N/A (off chart) 0.250″ 0.187″ 0.145″ 0.124″ 0.105″ 0.0905″ 0.082″
8.0 N/A (off chart) 0.307″ 0.232″ 0.180″ 0.1485″ 0.130″ 0.122″ 0.111″
This chart gives recommendations for width of conductor needed to carry current on different copper thickness.
Stripline Impedance:
Dielectric
Thickness
Impedance
  20 40 60
  Conductor
Width = W
0.002″ 0.007″ 0.004″ N/A
0.003″ 0.012″ 0.006″ 0.003″
0.004″ 0.016″ 0.009″ 0.005″
0.005″ 0.021″ 0.0012″ 0.007″
0.006″ 0.026″ 0.015″ 0.008″
0.007″ 0.030″ 0.018″ 0.010″
0.008″ 0.0035″ 0.020″ 0.011″
0.009″ 0.039″ 0.023″ 0.013″
0.010″ 0.044″ 0.026″ 0.015″
Based on 1 oz. (0.0014″) copper conductors separated by polyimide, with a dielectric constant of 3.4 at 1 Mhz. These are for estimation only.

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