P
Pasquale
- Jan 1, 1970
- 0
Hello to everybody,
anyone of you knows how to fix an Heatsink for DPAK on PCB ?
Thank you,
Pasquale.
anyone of you knows how to fix an Heatsink for DPAK on PCB ?
Thank you,
Pasquale.
The DPAK is designed to be soldered to the surface of a PCB.
If you want to use a metal heat sink, you should probably
look for a TO-220 version that is made to be mounted on a
heat sink.
Pasquale said:Hello to everybody,
anyone of you knows how to fix an Heatsink for DPAK on PCB ?
Hello to everybody,
anyone of you knows how to fix an Heatsink for DPAK on PCB ?
Thank you,
Pasquale.
Pasquale said:Thank you very much.
I'm gonna do a copper area large enough in order to fix the DPAK and the
Heatsink for DPAK. Do you think is it ok ? I have a MOSFET DPAK where the
drain should lies on the copper area. What do you think is the best way
to solder it ? Remember that I should solder it by hand.
for reflow soldering.
What equipment do you have available?
BTW, have you done the thermal calculations to figure out what size
heatsink you actually need?
Pasquale said:Thank you very much.
I'm gonna do a copper area large enough in order to fix the DPAK and the
Heatsink for DPAK. Do you think is it ok ? I have a MOSFET DPAK where the
drain should lies on the copper area. What do you think is the best way
to solder it ? Remember that I should solder it by hand.
Slightly tricky as they're normally soldered using paste. However if you do
it carefully you may be able to 'flow' some solder under the package but not
that won't work with leadfree solder because it has no surface tension to
talk of.
You may have a bit of trouble soldering this by hand. They are designed for
reflow soldering.
True, that's what they're designed for, but for a part with a pad more
than a few mm by a few mm (for example the TO-252 has a pad 6.5 x 6 mm,
quite big by most SMT standards) I find that a plated-through hole big
enough for my soldering iron tip lets me do a very decent job of getting
the part attached to the board. I'm sure there's some loss off cooling
ability because there's no copper under part of the pad but I'm not
pushing the limits.
Tim N3QE
I'm really interested in what you have done. Could you, please, send me
some pics or something in order to understand better ? Or some links
where I can check your procedure ?
Actually I don't have really good equipment (I have the stuff to solder
by hand, "regular" equipment), for sure I don't have a reflow solder
station. I know that is gonna be difficult but how can I manage to solder
it by using "regular" equipment ? I need suggestions in order to get the
best result with the equipment I have.
thermal pad in a rectangle of copper. To solder the device to the plated
through hole, turn the board over, stick the soldering iron through the
hole to heat up the device and the board, when it gets hot enough to
melt solder all around, stick in the solder and flood the hole. Solder
will wick between the device and the copper pad.
I used this for a low-scale production AD9954 DDS a few years back.
Having the board pretinned helps a bit if you aren't used to it.
Having the hole of a good size for your soldering iron tip really helps.
If not, you won't directly heat the devices thermal pad, just the board.
Tim.
Thank you very much. I'll try your method. What about the heat ? I'm
trying to do some calculation if I need a heatsink or not. How did you
manage that ? I've see that I should use the Rthjc, Rthja and so on but
maybe a bigger copper pad will work. What do you think ?
Thank you,
Pasquale.
First you need to know how much power your device is going to dissipate.
This value will depend on how it's used in your circuit. If you don't
know how to calculate this far then I suspect you may have more to worry
about than whether or not you can solder a heatsink!
Dave.
Pasquale said:I know, more or less, how much power my device will dissipate. For the
MOSFET should be something like Pd = Rds_on*I^2. For this reason I'm
trying to understand how to choose the right heatsink,
Pasquale said:I know, more or less, how much power my device will dissipate. For the
MOSFET should be something like Pd = Rds_on*I^2. For this reason I'm
trying to understand how to choose the right heatsink,
If it's switching at high speed you also need to add the switching
losses.
Graham