Re: gEDA-user: PCB Libraries

["John Luciani" <jluciani@xxxxxxxxx>]

It does not appear that the terminals on the SOT-227 were designed to
be attached to a PCB. Isn't there a gap between the tab and body that
would crush if you tighten a screw without a terminal inserted?  You
are unlikely to get a lot of thermal conduction through the terminals
which is why the manufacturer has such a large tab. You may want to
consider a different package if you do not want leads. The tab on
this package is isolated so you could mount all four devices on
one heatsink.

You need to determine:

  * The maximum junction temperature you can tolerate
    to achieve your reliability goals
  * How much power each device dissipates
  * The thermal resistance of your heatsink
  * Other cooling options such as a moving air

Design your circuit such that peak junction temperature of the IGBT is
below the maximum junction temperature (150degC for your IGBT).  If
you are running at a low duty cycle and the on-time of the IGBT is
less than 50mS calculate Rjc using the "Normalized Thermal Respsonse"
graph and equation on page 7 of the datasheet.

(* jcl *)


On 3/12/06, Marc Price <mark.price13@xxxxxxxxxxxx> wrote:
> What I was also wondering is does this part generate heat and need a
> heat sink, i was thinking
> to have large wide tracks with holes in the pcb lined up to the 4 screws
> on top of the IGBT i was gonna use 4 of these transistors and then
> attach them to the heat sink so there was no wires.
>
> Marc :-P
>
> Marc Price wrote:
>
> > Cant find anything in the pcb libraries for  a
> >
> > JEDEC STYLE SOT-227B
> >
> > any ideas anyone
> >
> > Ive attached the pdf
> >
> > Marc :-P
>
>
>


--
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