I've never gotten those large QFN packages to work. QFN8 is the largest
I've even made work.

Lotsa luck!

--Bob

Trevor Page wrote:

>Hi list,
>
>I have produced a design for a small wireless device that uses an
>18LF252 in a 28-pin SO package. I need to reduce the size of the PCB if
>possible, and I am thinking about using an 18LF2520 in a 6mm^2 28 pin
>leadless QFN package. Hopefully these boards will be machine assembled
>eventually, but I will initially need to be able to hand-solder around a
>hundred of these boards, and so that leads me to the obvious question:
>can these packages be realistically hand-soldered by someone who is
>competent with working with SMT devices? 
>
>I notice that the QFN package has a large ground pad in the centre. I
>guess that it is necessary to solder this area to the PCB for mechanical
>strength, is that right? Would it be very difficult to solder reflow if
>I provided a few vias underneath the device and used a heatgun, paste
>etc?
>
>Would I be strongly advised to stick to the larger SO package?
>
>Thanks,
>
>Trevor.
>
>
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