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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