Bernie Posted September 9, 2010 Share Posted September 9, 2010 Servo DogI am wondering why the heat-sinks are not touching the MOSFETs under them. Is this a new design technique? Are the heat-sinks pulling the heat out of the circuit card around the MOSFETs ??? Just curious. Maybe my card is a misfit.. duno. Does anyone else have this problem? Link to comment Share on other sites More sharing options...
Max-Paul Posted September 10, 2010 Share Posted September 10, 2010 By not touching, are you talking about the possible fact that there might be a insolating pad under the MOSFET and on top of the heat sink? I ask cause I do not have a heat sink on my DC board (not drawing enough amps, 20ma per channel).I think I had heard that the tabs on the MOSFETs is hot or connected to one of the leads. Thus the MOSFETs would short out to each other is not for the isolation pads. Link to comment Share on other sites More sharing options...
LightORamaDan Posted September 10, 2010 Share Posted September 10, 2010 What you are seeing is correct...For those who do not have a ServoDog in front of them, the mosfets on that card are surface mount. With surface mount, the "tab" is the bottom of the mosfet and is soldered to the card. The heat from the mosfet is sent into the copper trace on the card. The heatsink which sets over the mosfet, has two legs that straddle the mosfet and are soldered to this copper trace.Thus the heat comes out the metal tab in the bottom of the mosfet, into the copper, into the heatink.Dan Link to comment Share on other sites More sharing options...
Max-Paul Posted September 10, 2010 Share Posted September 10, 2010 Interesting. Thanks Dan for the verbal discription. Link to comment Share on other sites More sharing options...
Bernie Posted September 10, 2010 Author Share Posted September 10, 2010 Dan's the man, thanks for the clarification... I was looking into this last night and I believe I was mistaking when I said MOSFETs, the voltage regulators are under the heat sinks.. Thanks again... Link to comment Share on other sites More sharing options...
LightORamaDan Posted September 10, 2010 Share Posted September 10, 2010 Bernie wrote: Dan's the man, thanks for the clarification... I was looking into this last night and I believe I was mistaking when I said MOSFETs, the voltage regulators are under the heat sinks.. Thanks again... You are correct.... There are mosfets on that card but they do not have heatsinks... SO if you take my post and substitue the words "voltage regulator" each place I said mosfet then things will be cool:cool:Dan Link to comment Share on other sites More sharing options...
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