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Date: Tue, 29 Nov 2011 15:28:42 +0100
From: Attila Kinali <attila AT kinali DOT ch>
To: geda-user AT delorie DOT com
Subject: Re: [geda-user] Re: I want to do BGA prototype soldering
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On Mon, 28 Nov 2011 09:49:04 -0600
John Griessen <john AT ecosensory DOT com> wrote:

> On 11/28/2011 04:45 AM, Attila Kinali wrote:
> > On Sun, 27 Nov 2011 22:18:58 -0600
> > John Griessen<john AT ecosensory DOT com>  wrote:
> >
> >> .8mm -- is that big enough to "do at home"?
> >
> > Yes and no. Yes, you can do it, no you need a good fan
> > (not the usual ones you get at hardware shops) and some
> > experience how to do it.
> 
> By fan, are you meaning hot air blower, or heat gun?
> Like my 1650 Watt version?

Er.. yes.. sorry. The language barrier got me here..
I meant something like the "HOT JET S" from Leister with a 5mm nozzle.
Ie something that has a fine airflow and temperature control and that
you can move precisely.

> > It's in my opinion easier to get a small electronics oven
> > (like the one sold by elektor) and solder the BGA in there.
> > Although other people report that using a normal kitchen oven
> > works well for them, i do not recomend that as you have hardly
> > any control on the temperature curve.
> 
> But modified with a ramp controller?

The elektor oven already has one:
https://www.elektor.com/projects/smt-oven.1372709.lynkx

 ==
> 
> On 11/28/2011 09:07 AM, Bob Paddock wrote:
>  > BGA's are still better than LGA's or even QFN's.
>  >
>  > The latter are a nightmare to get the flux out from under if your aim
>  > is ultralow current, and want a service life of years.
> 
> Thanks, hadn't realized LGA's, qfn's were worse.
> 
> Is there a technique for doing those first few prototypes
> washout well, or just plan on them not being usable long?

Actually, DFN/QFNs can be soldered with a standard soldering iron
and an ultra fine tip, if the footprint has long leads that come
out under the package and if there is no exposed pad.
The exposed pad is... ugly...

Also a few types of DFN/QFN packages have leads which are not only on the
under side of the package, but also continue a little bit up the sides.
Which makes soldering a lot easier.
 
> 140 degrees F is what I've been told about water washout of flux.
> maybe a water pik pump would survive that temperature?
> Else, is pouring a stream of hot water from 2 feet up good for
> dislodging flux under BGA's?

How about using better solvents? Like pure petrol or alkohol...
Aceton is also not bad. What works depends on the exact type
of flux.


			Attila Kinali

-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
		-- Tirin, The Dispossessed, U. Le Guin