Despite the apparent norm (?) of using "dedrossing" blankets ,
i did (holis, seho, etc.) conclude it's a mess to be avoided .
Totally agree with Justin , only thing being extremist i went all the way :
One of those early days (-20years) i landed with same problems like Hans.
Being a tinker like Justin, took it all apart cleaned up, filled oil back in
as per manuals,
slept on roses for few months , problem came back .
Repeated strip , filled oil , decided on cunning move and surprised the
system with secondary strip
week after . Guess what :
The rotating shaft of the pump creates a film thin whirl sucking the thin
hot oil down the shaft ,
and slowly but certainly balling up the impeller ; with fine particles of
dross in it .
Once the mass accumulated on pump impeller reaches certain limit ,
than it gives out as much as takes on .
I may get shot for this heresy ,
my choice is keep the pot clean (daily) , no additives at all (including
pump shaft fence).
One tip for daily maintenance :
get a flat painters stainless 2" spatula, gather the dross to one corner ,
than utilize the flex for squeezing solder out of the dross against the pot
wall ,
"flicking" over edge virtually dry segments .
This did beat all oils and powders complications, costs,
and got down the pump strip to once a year/1shift .
Basic start is to clean (chisel if you have to) all to metal
(watch those titanium "coated" bits if you have any).
Weekend work , just bearable with couple of stubbies over lunch.
Don't make the mistake of leaving anything not cleaned ,
regadless how mild it may look = giving the job to less meticulous party
backfires.
And , yes , 245C+/- helps.
paul
-----Original Message-----
From: Justin Braime [mailto:[log in to unmask]]
Sent: Wednesday, 23 August 2000 6:25
To: [log in to unmask]
Subject: Re: [TN] Wave Flow Solder Problem
Hi Hans
Woweee!...what a load of gunk!
I had similar experience with an old EPM machine a few years back.
I emptied the solder pot, removed it, took of all the elements etc, then I
took it outside and attacked it with shedloads of degreasant :-) Did the
same for all the nozzle bits, pump shafts - the lot.
Re-assembled (looking nice and shiny) and NEVER used tinning oil again!
We only used oil around the pump shaft (little enclosure needed)
Reduced the pot temp to reduce drossing, and used Kleenox powder for
de-drossing - much better option than oil throughout.
You have my sympathies!
Good luck
Justin Braime
------------------------
Process Engineer
Compuspec Industries Ltd
Auckland, New Zealand
----- Original Message -----
From: Hinners Hans Civ WRALC/LYPME <mailto:[log in to unmask]>
To: [log in to unmask] <mailto:[log in to unmask]>
Sent: Wednesday, August 23, 2000 7:31 AM
Subject: [TN] Wave Flow Solder Problem
Hi Everybody,
I've been asked to troubleshoot a BIG problem with our wave flow soldering
machine and I could use some advice. I'm in the beginning stages of
learning about wave flow soldering.
We use Tin Lead 63/37 solder with Kester-5738 Dross Inhibiting Oil and, to
date, my solder analysis has come back fine.
And recently, we've been getting alot of bridging on assemblies (multilayer
FR-4). No surprise really, there is an embarrassing amount of scum
(dross-?) and our Tinning oil is gunking up. We've only used this oil for a
few months so it's the only reported process change. The joints look It's
an old Hollis machine (bought in '83) that has seen better days. The first
thing management said was, "Should we go and buy a new machine?" Showed
Kester the pics and they said the oil was at the end of its life and broke
down.
I threw a couple of pictures on my public drive starting with the word
'Solder -'. I kept them fairly large (~500 k each) so people can get a good
idea of what I'm up against. For the digital buffs, they're scaled down 60%
from the originals using a Sony DSC-D700 camera.
http://www.driveway.com/share?sid=a8f3cb1d.96df8
<http://www.driveway.com/share?sid=a8f3cb1d.96df8&name=Pictures>
&name=Pictures
Thoughts, questions, suggestions, . . . . prayers?
Do we just need to scoop the gunk out (that was my weekend) and keep going?
Start over with a fresh bath of solder?
The more I do, the more I learn . . . the hard way.
Hans
~~~~~~~~~~~~~~~~~~~
Hans M. Hinners
Materials Engineer (Process & Manufacturing)
Warner Robins Air Logistics Center
Avionics Production Division
Manufacturing Branch
380 Second Street, Suite 104
Building: 640, Mail Stop: LYPME
Robins AFB, GA 31098-1638
Voice: (478) 926 - 1970 Fax: (478) 926 - 7164
mailto:[log in to unmask] <mailto:[log in to unmask]>
http://www.robins.af.mil <http://www.robins.af.mil>
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