[sdiy] Another new hard to find part....

[Magnus Danielson]

From: karl dalen <dalenkarl at yahoo.se>
Subject: Re: [sdiy] Another new hard to find part....
Date: Wed, 7 Jul 2004 01:18:37 +0200 (CEST)
Message-ID: <20040706231837.28050.qmail at web53506.mail.yahoo.com>

> --- René_Schmitz <uzs159 at uni-bonn.de> skrev: > Hi Paul and R.D.
> 
> > I would in tendency agree 1.27mm chips are no problem, I've even done 
> > 0.65mm pitched chips. Discretes in 0806 or similar sized outlines are 
> > easy to work with. SMD has one big pro, you don't have to turn over the 
> > PCB that often, and pinch off wires, so that you can work quicker.
> > But if you try some BGA chips, the honeymoon is over!
> 
> Ha! BGA is the easiest to solder and to desolder, simply
> use a paste mask and oven for soldering, use a heat gun
> for desoldering.

There are good jigs for both soldering and desolering BGAs. Both Weller and
Metcal has them, but they are slightly over the average DIY soldering iron.
Hot air and pre-heating is the main tricks in the BGA trade. However, if you
just got your BGA fairly closely in place, the surface-tension of the solder
will do the rest of the work for centering X&Y as well as small turnings of the
chip (classical problems with PLCCs and friends in small pitch).

BGAs is a real blessing really. It is not DIY-friendly yeat, but I have a
friend who is destined to do it. He may even figure out how to do it "Out in
the woods, far away from electricity... just for the sake of it!", but I will
be quite happy if I could do it. The big problem isn't soldering as such, doing
stuff like 4 layer or more with vias etc. at home isn't very DIY friendly to
say the least. Hey, I would be happy if I could do 2 layer WITH vias at home.
I need that alot really.

> I find LQFP pain in in the rear end to solder, particularely
> when pins exeed 32!!

Tell that to the man who had to "correct" for the wrong foot-pattern between
PCB and ordered component for a 208 pin LQFP!
http://ebs.homedns.org/tips/hantverk/ytmontering/gal.jpg

Notice the pin-extentions? 0.1 mm silver leads. Oh, by the way... this card
worked after this "correction". Let me tell you, that "engineer" got his
lesson tought. Now you know why one wants a good man by the soldering iron on
a bad day.

Cheers,
Magnus