Re: Fwd: Re: gEDA-user: Plastic Ball Grid Array (PBGA) packages?

[Egil Kvaleberg <egil@xxxxxxxxxxxx>]

Stephen Meier wrote:

> Placing a BGA device is not a hand solder job. It is done in an oven 
> along with all the other devices or on a specific, fairly expensive, 
> piece of equipment.

I remember back in 1999, when visiting a cellular phone startup company, 
"the guy" in their lab hand soldered >160 pin micro-BGA chips with an 
astonishing success rate (comfortably over 90%). He also replaced chips 
this way, as a matter of course.

Seeing that it was possible, made it possible for me to repeat it at 
home. The success rate was less, but good enough for my purpose. I never 
did this enough times that is became second nature.

The trick is to use a temperature controlled hot air blower with a 
continuously selectable air flow. With a suitable, small, nozzle, the 
$150 or so Steinels work just fine. You need to get the temperature 
right, use a low air flow, make sure everything is clean, and use a 
suitable flux. You direct the hot air flow at a 90 degree angle, so that 
the chip is free to 'settle' correctly on the pads. You will develop a 
'feel' of what is enough heat. When the surrounding decoupling caps 
start to blow away, you have more than enough.

And yes, you really also need a PCB with a good silk screen to make it 
possible to align the part properly before starting. Lightly support if 
with a pair of tweezers until the tin melts, after which the capillary 
forces of the tin takes over.

In 2003, they are no longer a startup - I'm sure they can afford the 
equipment, but in their lab "the guy" is still doing the same thing with 
the prototypes. Because it is quicker, he says.

For initial production of the prototypes, they  rely on a 'house', 
obviously.

If this will work with conventional BGA, I haven't tried. At the very 
least, you need a larger nozzle and more heat.

And keep in mind: I am not recommending this technique. In a situation 
with many unknown, as in an initial prototype, I'm sure the last thing 
you want is an extra unknown. BGA is a real PITA if something is wrong, 
and you suspect there may be a bad connection.

But what I'm saying is that it *is* possible to hand solder.

Egil