[ILUG] OT: hot air soldering station

[Brendan Minish]

On Sun, 2010-04-25 at 20:50 +0100, Brendan Kehoe wrote:
> I'm trying to fix a friend's laptop which is suffering all the  
> symptoms of its nvidia chip being slightly unseated from the  
> motherboard.

Presumably you have ruled out tin whiskering ?

> I've tried using the heat from a soldering iron and a hair dryer, but  
> they didn't do the trick.

The Hair-drier is not hot enough to do anything useful and may actually
reduce the surface temperature of the part due to the air flow (think
80C air blowing across a part at 225C ..)  

> Don't suppose anyone near Dublin (or, to tempt fate, near Dun  
> Laoghaire) would have a hot air soldering station I could borrow to  
> try the real 300-degree way to melt and re-seat the solder around the  
> nvidia GPU's pins? :-)

Is a standard Surface mount part or a BGA part?
http://en.wikipedia.org/wiki/Ball_grid_array
If it's BGA then the simply reheating is not likely to achieve the
desired result since you run the risk of un-soldering other connections.
For reasonably reliable results with BGA devices you need a full rework
station and be well skilled in using it 

If it's not a BGA device but a standard leaded surface mount part then I
have always had great results when constructing or reworking these with
a fine tipped soldering iron, good quality fine flux cored solder and
solder removal wick. The Trick is to solder the part and not worry too
much about bridges between the leads, after you have soldered all leads
use the solder removing wick to remove all excess solder.

I would recommend using a tin/lead/silver solder mix for surface mount
rework, radionics # 551-671 is an excellent choice and is also a very
good general purpose solder 
http://radionics.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0551671

The ROHS (Lead free) solders require considerably more skill to use for
fine rework.