On Thu, 31 Jan 2008 10:06:08 GMT, "Arfa Daily" wrote:
:
:"Ross Herbert" wrote in message
.. .
: On Thu, 31 Jan 2008 01:20:59 GMT, "Arfa Daily"
: wrote:
:
: :
: :"Ross Herbert" wrote in message
: .. .
: : On Wed, 30 Jan 2008 09:34:29 -0600, Ignoramus19508
: : wrote:
: :
: : :On 2008-01-30, Ross Herbert wrote:
: : :
: : : Your desoldering tool (like most) is probably fitted with a small
: : diameter
: : tip
: : : (approx 0.8mm - 1.00mm inside diameter)
: : :
: : :Yes.
: : :
: : : designed for sucking solder from around small gauge component leads
: : : and IC pins where the tip make full peripheral contact with the
: : : board. When the solder melts around a pin all the air passes solely
: : : around the lead and maximum effect is achieved inside the through
: : : hole.
: : :
: : :Well, it does this pretty well with a real vacuum pump attached
: : :instead of the "desoldering station pump".
: :
: : Yes, of course it will. But the desoldering station pump is NOT a
: : specialised
: : 1/3HP vacuum pump. It is designed as being adequate to suck solder from
: : around
: : component pins ONLY when the nozzle completely surrounds the lead AND
: make
: : 100%
: : peripheral contact with the pcb solder pad.
: :
: :
: :Well Ross, I gotta tell you that I use my Weller desoldering station just
: :about every day, I keep the same sized tip on it with a 1mm hole at all
: :times. It is used both for pin sizes where the hole will fit over the
: pin,
: :as you describe, and also for any other joint that I need to get the
: solder
:
ff as well. I have never had a problem with it developing enough suck to
: :remove solder from a joint that requires the tip to be applied in a way
: less
: :than your stated 'ideal', unless it has reached the point where it needs
: :servicing. I think that in common with most soldering / desoldering
: tools,
: :it depends on how often you use it, and hence how much skill in its use,
: :that you have developed.
: :
: :Arfa
: :
:
: Yes Arfa, I agree with what you say. I also can use my Hakko to remove
: solder
: from around larger pins quite quickly, but due to the large amount of
: solder
: which often must be removed from large terminals, several attempts may be
: required and sometimes the tip requires a clean out to complete the job on
: a
: single switch. I can't say if there is anything wrong with the OP's
: desoldering
: station, although this may be the case. I find that for small number of
: large
: terminals the old Soldapult takes less time and requires less cleaning.
:
:For many years, I used a desoldering pump with great success. Then I took on
:a contract that required me to have the desoldering station running just
:about all of the time. It became easier to just pick up that iron 'ready to
:go' than to start hunting around for the hand sucker, so that's what
:happened ! Using it all of the time like this, you develop techniques for
:'making it work' on just about any sort of joint, but I do agree that it
:does sometimes take a couple of attempts to get enough solder off the joint,
:and it has to be kept well maintained. I do still use a good quality solder
:wick - expensive, but worth every penny - to 'clean down' in preparation for
lacing a s.m. IC for instance, and occasionally, for clearing out a
:stubborn thru' hole that just won't suck clear, no matter how well your iron
r sucker is working, and how much new solder, you get into it. Bet you've
:been there ... !!
:
:Arfa
:
I have sure been there... On those "difficult to totally clear" holes I
concluded that the main cause was that the through-hole diameter was not quite
big enough to allow sufficient lead displacement during the "wiggle and suck
phase". The lead could not get clearance from the side of the hole to allow
molten solder to pass by. That is one of my major complaints about some board
designers - they seem to pride themselves on saving as much board territory as
possible, even though the board is not crowded. My motto is to make lead
mounting holes capable of allowing a fair clearance around whatever size lead is
to be fitted, not the minimum size which will barely allow clearance for the
largest pin diameter for any component on the board. One size doesn't fit all
and if it means an extra drill size then so what. It makes for easier component
removal, if needed, later on.
Sometimes adding extra solder and flux would assist but not always. When this
happened I would resort to a pure liquid activated flux which sadly is no longer
produced, Magna Alloys type 87. I still have a small quantity left but when that
is gone...
As for final clean down of smt pads, yes, you can't beat a good quality
solderwick, or as you would say, soderwick. However, much of the product around
today doesn't work very well so it is best to pay for the quality brands such as
that made by Multicore or ITW Chemtronics as Solder (or Soder)-Wick or
Chem-Wick.
http://www.chemtronics.com/products/product.asp?id=88