Dear 'Netters,

We have a product used to measure on/off status on flat screen TV's that was designed a few years ago.  Over time, with the newer, bigger TV's, there is a much higher current draw than we'd envisioned way back when.  So, as the devices cycle back through our repair depot, we're making mods to upgrade them to handle these new TV's.  A problem we've seen in testing is that the traces that handle the AC pass-through are now getting quite warm.  We've measured the traces at 105*C at room temperature.  The base is plain old FR4.  We haven't been able to get any to fail in testing, but are concerned about the differential under load possibly causing the trace to peel away from the FR4.  Our concern is thermal cycling over time; could it cause the trace to lift?  If the trace is hot but the board cool in a steady state condition, is there any risk there?

Does anyone know of any specifications that would address this situation?

Bob Croslin
Nielsen Media Research



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