Temperature Rise vs. Current
This design chart has been prepared as an aid in estimating temperature rises (above ambient) vs. current for various cross-sectional areas of etched copper conductors. Include a 20 % de-rating for unknown variations. Additional current de-rating of 15 % is suggested for conductor thickness of 0.0042 inch (.11 mm) (3 oz/sq ft) or more.
For single conductor applications the chart may be used directly for determining conductor widths, conductor’s thickness, cross sectional area, and current-carrying capacity for various temperature rises.
Circuitry Design
For groups of similar parallel conductors, if closely spaced, the temperature rise may be found by using an equivalent current. The equivalent cross-section is equal to the sum of the cross-sections of the parallel conductors, and the equivalent current is the sum of the currents in the conductors. The effect of heating due to attachment of power dissipating parts is not included.
The conductor thickness in the design chart do not include conductor over plating with metals other than copper.
Material CTE’s
COPPER – 18 ppm/deg C
KAPTON – 25 ppm/ deg C (x,y) and 100 ppm/ deg C (z)
ACRYLIC ADHESIVE (<tg 40C) – 100 ppm/ deg C (x,y,z)
ACRYLIC ADHESIVE (>tg 40C) – 400 ppm/ deg C (x,y,z)
POLYIMIDE ADHESIVE ( <tg 170C) - 150 ppm/ deg C (x,y)
Copper thickness
PFC has the ability to provide Circuits utilizing 560 micron thick copper for power applications.
Available Copper weights for power applications in microns include:
70 (2oz.), 105 (3 oz.), 140 (4oz.), 175 (5oz.), 245 (7oz.), 420 (12oz.), and 560 (16oz.).
Call PFC to assist with your high current circuit design.