Lpc2000

Hi, Thanks,
Tool used here is a handheld Leister CH-6056 hot-air blower/
desoldering tools (~US$400 cheap tool)  This tool is meant for
removing SMT/QFP parts and is NOT a proper BGA rework tool.  
Will try your way of pre-heating PCB and make sure solder balls do
not get "sandwiched" too much, also reducing that air-flow rate.
Regards

--- In lpc2000@yahoogroups.com, Greg Deuerling <egads@...> wrote:
>
> 
> > Of unity0724
> > Sent: Tuesday, January 31, 2006 7:21 AM
> > To: lpc2000@yahoogroups.com
> > Subject: [lpc2000] Re: Philips LPC3180 - BGA loading Qs
> > 
> > --- In lpc2000@yahoogroups.com, Greg Deuerling <egads@f...> 
wrote:
> > > I use a hot air re-work machine and it does a great job.  The
> > > great things about BGA's are they are self centering.  They 
can be
> > > off pad up to 60% and when the balls flow they will pull the
> > > package into proper alignment.   For a big production run you 
want
> > > to go to a place that does IR re-flow, but for the qnt we do 
here
> > > our hot air machine work nicely.  It's not all that
> > > hard!!!
> > 
> > We used hot air blower (600W SMT rework/desodlering tools) to 
solder
> > BGA on prototype boards but could only get 20-30% successful 
rate.
> > Difficult part would be chip blown completely out of PCB 
footprint.
> > Self-centering does not always pull the chip back to proper 
alignment
> > also.   Any special skill/experience to share??
> > Regards
> 
> Special skill's?  Yes, lots of practice and the temperature and 
timing have
> to be closely controlled.  I recently mounted 40 672pin PBGA's and 
had a
> 100% success rate.  Altera and Xilinx will usually give you 10 or 
so dummy
> packages to practice on before you try to place that $1000 FPGA 
the 1st time
> :)
> 
> Our system heats the PCB from the top and the bottom board.  We 
use a three
> step process:
> 
> 1) Pre-heat the PCB to 200C for a minute or so.
> 
> 2) Next soak the PCB to just 20-30C under where the solder starts 
to flow
> for 2 minutes.  Most 10 to 12 layer PCB's I use 230C.
> 
> 3) Next hit the PCB with enough heat to flow the solder for 10-30 
seconds.
> Most 10 to 12 layer PCB's I use 300C for 10 seconds.  This is the 
real
> trick, you only want to flow the solder for a very short time or 
the package
> will lay down too flat and short out balls.
> 
> The air speed on the above steps is pretty slow.  I've had 0402 
cap's that
> were not held down by anything but solder paste and they did not 
blow away.
> 
> We use a Metcal/OKI BGA-3500 series re-work station.  Metcal does 
not make
> the BGA-3500 any more, but I think the APR-5000 replaced it.
> 
> See: http://www.okinternational.com/product_advanced
> 
> 
> 
> Greg Deuerling
> Fermi National Accelerator Laboratory
> Feynman Computing Center, Room 370, MS 368
> P.O.Box 500 Batavia, IL 60510
> (630)840-4629     FAX  (630)840-8208
> Electronic Systems Engineering Group
> Work: egads@...
>