this post is stemming from the "new adventures" found in the new thread by manateemafia MX reference
due to a lack of an actual ability to see inside an enclosure, i resort to femm4.2 to try out some disspation simulation. it appears copper clad PCB may leak alot more heat than needed?
in my crude simulation, the LTZ sit inside a 30mm foam ball, which is sliced thru by a PCB. the left n right half are different PCB. right half is full thick 1.6mm PCB 2oz, left is suppose to mimic slotting and 1oz copper. and for the fun of it, the edge is mated to the outer box. a funny carbon box inside a foam skin.
(since femm4.2 does not have all the materials, most of the chosen materials nearly matches PCB, silicon, copper, ABS, etc.)
the femm have a plot function, which seem to describe a steeper temp isolation (lower plot) for the modified left side (pic T-grad.gif) vs the right side (upper plot).
while it is true everything inside a project box will be heat up, however if in the case of a LTZ (non-A) if we assume it can be foam isolated to increase the thermal resistance to 400C/W just like an A version, wont it be a boon?
but as i try to math it out, a KOVAR pin/leg about 2mm long x 21mil, can have its thermal resistance estimated at approx 520C/W. for 8pins = about 65C/W. so for the stated stable thermal resistance inside LTZ pdf (=80C/W), the pins alone is the single most leaky "heat channel" (for all the pins to get 80C/W, they need to be at least 96mil long). this imply the LTZ heater need to work alot more harder pushing out heat to short pins, so in theory if the pin landing no longer need to be heated as vigorously by ramping up thermal resistance, should the zener voltage become more stable?
mass of LTZ1000 ~ 1g
mass of 3cm foam ~ 0.02g
mass of 1.6mm FR4 400mil diam ~ 1.6g ??
due to my above assumptions, since the 8 pins carry a heavy thermal influence, wont this require more attention to remove more thermal mass around the pin landing? so that the LTZ only try to adjust/compensate its own temperature and not the entire PCB?
(rename **.txt to **.FEH to use in femm)