Re: SMT mounting question

From: David Wood (jbevren_at_starbase.globalpc.net)
Date: 2002-10-16 09:52:08

I'll quote from two previous messages to save some reply traffic :)


Marko, Agreed.  My oven can go well beyond the soldering profile specified
on the datasheet for the IC.  I'm at work, so I'm taking a guess here.  The
profile had a peak temperature of around 218c, which any household oven can
reach.  However, I'm concerned about maintaining control over the
temperature.  For example, the peak temperature should only be maintained
for about 60 seconds, after which the board is to be slowly cooled.

Pasi,  Good idea.  I did get two ICs as can be seen in the diagram, so I
guess I have one to 'burn' (my normal methodology, but I had no intent on
tempting the literal meaning's fate). :)  Any hair dryer that can bake a
chip on will most certainly turn some poor girl's mop into a twisted smelly
mess. ;)  I will have to go and get a genuine heat gun.

However, I'm more concerned about the lack of control with a heat gun than I
am with an oven.  I can open the door a crack after I see the chip settle,
and wait for the oven to cool that way. :)

Next step: getting the traces out of that point array. :) I guess I'll have
to have a test board or two made.. that's gonna hit my pocket hard I'm sure.
:)  Does anyone know of prototyping PCBs with bga mount pads?

If things turn out to be reasonable enough for this IC, I'll probably end up
using it for UHS's primary controller.  It would save me a lot of *pld
hardware design time, and will offload filesystem and device handling from
the c64's CPU.  I'll explain my methodology in another post, as it's not
related to the acutal soldering of the IC.

-David


Marko ->>

Please reply to the list; many BGA chips could be used in interesting
Commodore hardware projects.

I don't have any personal experience on soldering BGA, but have you
considered mounting the chip on the board with some heat-resistant tape
or glue, and then putting it in an oven?  If I were to build something
with BGA chips, I'd design the board so that there are BGA chips only
on one side, and I'd solder these parts first.  The rest can be done
with a soldering iron.

        Marko


On Wed, 16 Oct 2002, Ojala Pasi 'Albert' wrote:

> > I don't have any personal experience on soldering BGA, but have you
> > considered mounting the chip on the board with some heat-resistant tape
> > or glue, and then putting it in an oven?
> 
> You can "solder" BGA chips quite easily with a hot-air blower:
> put the chip into the approximate position, then heat it with
> the blower. When the solder melts, the chip will align itself
> automatically. Then very carefully remove the blower, i.e.
> increase the blowing distance so that the chip remains aligned.
> 
> A normal hot-air blower for hair probably doesn't have enough
> power for this though..
> 
> -Pasi
> -- 
> "As well try to understand the sun, Perrin. It simply is,
>  and it is not to be understood. You cannot live without it,
>  but it exacts a price. So with women."
> 	-- Gaul in The Wheel of Time:"The Shadow Rising"
> 
>        Message was sent through the cbm-hackers mailing list
> 


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