3.2. Traces on ceramics substrate
6
We repeat the calculations for traces on typical ceramics
material (Al2O3) (thermal conductivity k=16 W/m-K) and
thickness D=1 mm and 0.5 mm.
8
7
9
(Continued from previous page)
Table 1: Mean temperature of a trace (in 20 degC ambient) as
function of electrical current for different PCB scenarios.
Base material of the board is FR4. Parameter is trace width
from 0.2 mm to 10 mm
Table 3: Mean temperature of a trace (in 20 degC ambient) as
It is clearly seen, that the more copper the board contains,
function of electrical current for traces on ceramics substrate.
the lower is the trace temperature, or, the higher the allowed
Parameter is trace width from 0.2 mm to 10 mm.
current. If we take a look at scenarios 2,4 and 6, which have
the same copper content, we see also that the thermal
resistance from the trace to the plane (i.e. the distance) Scenario Current I('T=20 K) Current I('T=20 K)
influences the temperature. To make comparison more w=2 mm w=10 mm
clearly, the current values of some designs for a t=35 μm 8 8.2 A 20.5 A
trace of width of 2 mm and 10 mm and temperature rise 9 9.8 A 23.5 A
'T=20 K are given in Table 2.
Table 4: Calculated current I leading to a mean temperature
Scenario Current I('T=20 K) Current I('T=20 K) rise of 'T=20 K for trace widths w=2 mm and 10 mm on
w=2 mm w=10 mm ceramic PCBs.
1 4.0 A 12.6 A
Traces on polyimide film
2 5.7 A 18.7 A
Finally, we show the results for traces on a thin (D=0.3
3 5.5 A 17.0 A mm) substrate, e.g. a polyimide film (k=0.3 W/m-K).
4 7.4 A 21.0 A Although this is not an exact representation of a flex-circuit,
5 8.4 A 23.6 A these calculations show that the thinner the substrate, the
6 7.0 A 20.2 A lower is the current-carrying capacity.
7 7.2 A 22.6 A
Table 2: Calculated current I leading to a mean temperature
rise of 'T=20 K for trace widths w=2 mm and 10 mm for
different board designs.
Adam, New Correlations Between Electrical Current and … 20th IEEE SEMI-THERM Symposium
Page: Previous 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Next
Last modified: September 9, 2013