Message	Date	From	Subject
1830	2008-07-22 18:58:59	Glen Leinweber	J310 lead frame heatsinking question
Transistor chips are mounted to a lead frame, most often with one of the connections made directly through the substrate to the lead frame. For example, a 2N3904 chip is mounted to the collector pin, with bonding wires for base and emitter connections. Most power transistors have collectors bonded to the metal mounting tab, and most power MOSfets have drain bonded to the metal mounting tab or lead frame. Looking at the J310 chip, I see bonding wire pads for gate, drain, and source. So its not at all clear which of the three might be connected to the lead frame. The U310 (in a T0-18 case) has gate connected to the case. It seems unlikely that the gate would be connected through the substrate to the lead frame. Do J310 T0-92 and SOT-23 packages use a lead frame with the chip bonded to one of the pins? If so, which pin? The reason I ask is that J310's can run with fairly high current, and might benefit from heat-sinking. Its often more effective to heat-sink the pin attached to the lead frame, rather than heat-sinking the plastic case.

Transistor chips are mounted to a lead frame, most often
with one of the connections made directly through the
substrate to the lead frame. For example, a 2N3904
chip is mounted to the collector pin, with bonding wires
for base and emitter connections. Most power transistors
have collectors bonded to the metal mounting tab, and
most power MOSfets have drain bonded to the metal
mounting tab or lead frame.
Looking at the J310 chip, I see bonding wire pads for
gate, drain, and source. So its not at all clear which of
the three might be connected to the lead frame. The U310
(in a T0-18 case) has gate connected to the case. It seems
unlikely that the gate would be connected through the
substrate to the lead frame. Do J310 T0-92 and SOT-23
packages use a lead frame with the chip bonded to one
of the pins? If so, which pin?

The reason I ask is that J310's can run with fairly high
current, and might benefit from heat-sinking. Its often more
effective to heat-sink the pin attached to the lead frame,
rather than heat-sinking the plastic case.