Homebrew PCBs

I've just made a breakout adapter PCB for a QFN32 device - the ADI
AD8333 Dual I/Q Demodulator and Phase Shifter. Making the PCB was
quite straightforward, although the pads are quite small and 0.5 mm pitch.

I've posted a pic of the assembled unit in my (Leon's) photos folder.

The hardest part of the assembly was getting the pads lined up
properly so that I could tack down two opposite corners. Once that was
done I applied plenty of gel flux to each row of pads and drag
soldered them, a row at a time, using a 1/64" conical bit cartridge
with my Metcal system. I haven't got any bridges and the joints look
OK. I used a stereo dissecting microscope (X20 magnification).

Leon

On Mon, 23 Oct 2006 22:37:44 +0200, leon_heller  
<leon.heller@...> wrote:

> The hardest part of the assembly was getting the pads lined up
> properly so that I could tack down two opposite corners. Once that was
> done I applied plenty of gel flux to each row of pads and drag
> soldered them, a row at a time, using a 1/64" conical bit cartridge
> with my Metcal system. I haven't got any bridges and the joints look
> OK. I used a stereo dissecting microscope (X20 magnification).
> Leon


Why don't you use paste and hot air? Works a treat, and gets the thermal  
pad too if there is one.

I don't think an iron is a good choice to solder leadless components, but  
it's good to know it would work, in a pinch.


ST

----- Original Message ----- 

From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, October 23, 2006 10:02 PM
Subject: Re: [Homebrew_PCBs] QFN32 breakout adapter


> On Mon, 23 Oct 2006 22:37:44 +0200, leon_heller
> <leon.heller@...> wrote:
>
>> The hardest part of the assembly was getting the pads lined up
>> properly so that I could tack down two opposite corners. Once that was
>> done I applied plenty of gel flux to each row of pads and drag
>> soldered them, a row at a time, using a 1/64" conical bit cartridge
>> with my Metcal system. I haven't got any bridges and the joints look
>> OK. I used a stereo dissecting microscope (X20 magnification).
>> Leon
>
>
> Why don't you use paste and hot air? Works a treat, and gets the thermal
> pad too if there is one.

I've tried that, but I got shorts between the pads.

>
> I don't think an iron is a good choice to solder leadless components, but
> it's good to know it would work, in a pinch.

The iron worked very well, I was quite surprised. A via works fine for the 
pad, with PTH boards, by heating it up and feeding in solder. I suppose the 
same technique could be used with a home-made PCB.

Leon

On Mon, 23 Oct 2006 23:45:40 +0200, Leon Heller  
<leon.heller@...> wrote:

>
>> Why don't you use paste and hot air? Works a treat, and gets the thermal
>> pad too if there is one.

> I've tried that, but I got shorts between the pads.

I've got bridges around the outside a couple of times, when i used too  
much paste. But they were easy to clean.


> The iron worked very well, I was quite surprised. A via works fine for  
> the
> pad, with PTH boards, by heating it up and feeding in solder. I suppose  
> the
> same technique could be used with a home-made PCB.

I drill a large hole and fill it with solder/copper braid. Taking care not  
to unsolder the thing.

ST