Homebrew PCBs

I want to switch packages on a design, I've been using a 44pin plc 
which is a reasonable challenge.  I'd like to go to a 28pin tssop.  
ANybody hand soldered one of these?

Thanks,
 Phil

Good question: I've got a similar challenge facing me.  A bunch of
components I need to use are only available as SM and I've never used
them on hand built boards. 

I'll extend the question: do I need special tools to work with SM
components for prototype boards ?  I'm used to using a chip clip to get
signals off DIPs.  Should I put test headers on SM boards ?    

-- 
Kim Lux,  Diesel Research Inc.

On Tue, 04 Jan 2005 12:11:08 -0700, Kim Lux <lux@...>  
wrote:

> Good question: I've got a similar challenge facing me.  A bunch of
> components I need to use are only available as SM and I've never used
> them on hand built boards.
> I'll extend the question: do I need special tools to work with SM
> components for prototype boards ?  I'm used to using a chip clip to get
> signals off DIPs.  Should I put test headers on SM boards ?
>

you must decide if you want to iron-solder the ICs or use an oven.

for testing headers are a good idea, i think for some smd packages there  
are test clips too.

ST

>  I want to switch packages on a design, I've been
> using a 44pin plc 
> which is a reasonable challenge.  I'd like to go to
> a 28pin tssop.  
> ANybody hand soldered one of these?
> 
> Thanks,
>  Phil
Its not bad under magnification. I avoid it, as its
time consuming, but  I've done a few boards with them.
Usually I cheat, and get my tech to build them... but
inevitably during test and debug, sooner or later I
need to replace it when he's not around.

A stereomicroscope makes doing so very easy. I have
done so with a magnifying head piece however. Lastly,
its a lot easier if you have solder mask... but with
care you can do so with a DIY board.

Ron

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

From: "Moore" <prmoore@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, January 04, 2005 7:03 PM
Subject: [Homebrew_PCBs] Hand solder 28 pin tssop?


>
>
> I want to switch packages on a design, I've been using a 44pin plc
> which is a reasonable challenge.  I'd like to go to a 28pin tssop.
> ANybody hand soldered one of these?

Quite easy if you use the 'drag-soldering' technique - tack down two 
opposite corners, apply plenty of flux, put a small amount of solder on the 
soldering iron tip and wipe the tip along the pins and remove any shorts 
with desolder braid. It can be done with an ordinary soldering iron but a 
Metcal like the one I use has a special tip: 
http://www.metcal.com/tips/minhoof2.html#fine

Leon 



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On Jan 4, 2005, at 2:11 PM, Kim Lux wrote:

>
> Good question: I've got a similar challenge facing me.  A bunch of
> components I need to use are only available as SM and I've never used
> them on hand built boards.
>
> I'll extend the question: do I need special tools to work with SM
> components for prototype boards ?  I'm used to using a chip clip to get
> signals off DIPs.  Should I put test headers on SM boards ?
>

One method it to "swamp solder" the part and then wick/suck up the 
excess.  Someone has a web site on this, but I can't recall the URL.  I 
do it with a hot air re-work station, but I sure miss the days when 
everything came in a DIP.  Of course with lead solder going away and 
new alloys coming into play we'll have even more headaches soon.

The Tssop28 is not a problem to work with,
you will need fine Tweeser, fine solder, a very fine tip.
and especialy "Magnifying glasses" and steady hands

It is easy to work with lead pitches of 0.5mm(0.020") or wider
i dont recomend the very fine 0.27 (0.012) lead pitches 

the main problemn with tssop28 is if your etching boards and do not 
have solder mask that you can easily short between the leads.
also if your using Toner transfer method the toner lines often will 
short durring the Heat transfer process.

BoonS

--- In Homebrew_PCBs@yahoogroups.com, Kim Lux <lux@d...> wrote:
> Good question: I've got a similar challenge facing me.  A bunch of
> components I need to use are only available as SM and I've never 
used
> them on hand built boards. 
> 
> I'll extend the question: do I need special tools to work with SM
> components for prototype boards ?  I'm used to using a chip clip to 
get

> signals off DIPs.  Should I put test headers on SM boards ?    
> 
> -- 
> Kim Lux,  Diesel Research Inc.

Randy Wilson wrote:
> 
> One method it to "swamp solder" the part and then wick/suck up the 
> excess.  Someone has a web site on this, but I can't recall the URL.  I 
> do it with a hot air re-work station, but I sure miss the days when 
> everything came in a DIP.  Of course with lead solder going away and 
> new alloys coming into play we'll have even more headaches soon.
> 


   Another vote for this, far faster than trying to do each pin seperately.  I 
do it with my regular solder sucker, just hold it a little further from the pins 
and it leaves just enough solder on the pins and pads.

In message <crepa0+d2nq@...>
          "Moore" <prmoore@...> wrote:

>  I want to switch packages on a design, I've been using a 44pin plc 
> which is a reasonable challenge.  I'd like to go to a 28pin tssop.  
> ANybody hand soldered one of these?

I've soldered an SSOP28 which is more or less the same as a TSSOP, just with
a larger body. I aligned it with blue-tack, then nudged it a bit with a
screwdriver to get the alignment absolutely bang on. Next I soldered two
opposite corners - the alignment was still OK, so I removed the blue-tack,
put some flux on the board (and lots of it!), put a bead of solder on the tip
of the iron and ran it down the pins. Repeat that for the other side, then
check for solder bridges and unconnected pins under high magnification and a
bright light. Clean off any bridges with desolder wick, then use Isopropyl
and a stiff brush to remove the flux residue.

Later.
-- 
Phil.                              | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB,
philpem@...              | ViewFinder, 10BaseT Ethernet, 2-slice,
http://www.philpem.me.uk/          | 48xCD, ARCINv6c IDE, SCSI
... I tell them there's no problems...Only Solutions...