Homebrew PCBs

----- Original Message ----- 
From: "Chris Warnes" <warneschristopher@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, January 20, 2004 3:33 PM
Subject: [Homebrew_PCBs] Gas Soldering Irons as hot-air pencils?


Hi Guys,

I am looking at options for a project I have underway,
which "unfortunately" requires me to solder a 100pin TQFP surface
mount component to a PCB (yet to be designed). There appear to be
various ways of doing this, but the one that I think I can manage is
using a hot air pencil. I've seen various designs modifying
desoldering tools but being in the UK they are quite expensive -
certainly not as cheap as \ufffd9.99 from RadioShack! I have found one,
from Rapid Electronics which is fairly priced at around \ufffd20, but it
is an "inline" desolder, and I am uncertain if this could be
modified. Likewise, there is no specified power output for it, so I
am unsure as to its suitability.

Another technique is to tack down the corners, apply plenty of liquid flux
and 'flood' the leads by dragging a blob of solder along them. Clean off the
excess solder with desolder braid and remake any suspect joints.

The other option I thought of is perhaps using a portable gas
soldering iron. Rapid again sell a 70W equivalent gas soldering iron
with a hot air tip, and I wondered if anyone has tried one of these
to see if it works?

My other concern is that I will be manufacturing the board using the
Resources at my University, which are just like any other "school"
PCB manufacturing tools using etching chemicals - am I likely to get
the "resolution" needed for etching the pads onto the PCB for this
component using the chemical etching process or will this also be
problematic?

If the lead spacing is 0.5 mm this could be tricky. 0.65 mm should be OK.



Leon Heller, G1HSM
Email: aqzf13@...
My low-cost Philips LPC210x ARM development system:
http://www.geocities.com/leon_heller/lpc2104.html