[hpsdr] [Fwd: Re: Flux sources? Some other ideas..]
John Nordlund
jnordlund at earthlink.net
Sat Aug 19 17:46:55 PDT 2006
Phil,
We were using Kester products at that time, though I could not tell you
what the product number was. The unused solder did however make
wonderful 45 caliber roundball for my muzzle loader. I was invited to
remove about 45 1lb rolls from the plant after the changeover. That is
a lot of 45 caliber ball..
I will add to this that I haven't used any water based products since
then, and they may be much better now that when the concept was
relatively new. As a company, Audio International changed to the 'no
clean' chemistry and never looked back. shortly after the change, they
sold off the $40k+ stainless steel 'dishwasher' that had been purchased
to clean up the boards from the production area.
Another issue we discovered that contributed to the high return rates at
the time was that some of the components would trap water and/or flux
residues inside their structure. The water flux contained a small
amount of hydrochloric acid in it's formula, and when that got inside
switch contact assemblies that had a tiny vent hole the acid would
dissolve the gold plating and then rapidly eat the copper conductors
leaving a switch contact that was either shorted by metal chloride
crystals or permanently opened by removing the connecting metal traces.
Since the majority of our products are switch modules this presented a
really serious problem to our quality program.
I was working as a production technician when the water flux was first
brought in for trials and the problem I encountered was that the flux
would boil before the alloy would flow and the boiling action would
interfere with the flow properties of the alloy. When the alloy arrived
at proper flow temperatures the flux had boiled away from the joint
leaving a dull dry finish on the component terminations and solder
lands. it was very easy at that point to wind up with a 'cold' joint as
there would be an oxide layer over the metal surfaces that interfered
with the flow of the alloy.
A few months later as an inspector in the quality department I was
examining these same issues under a microscope and all of the production
techs were having trouble creating clean solder joints consistently in
hand built assemblies. Soldering done in the reflow oven did perform
better, but there we did experience a larger number of components that
were displaced from their proper locations, requiring manual rework to
correct. It is my belief that this was caused by the boiling of the
flux during the passage through the reflow oven.
After changing to the No Clean flux chemistry the soldering problem
issues virtually ceased to occur. Now as the data analyst writing
reports on the returned items it is a very rare event when I have a
soldering related failure on items built after the change to No Clean
flux. One of our largest customers has a very interesting warranty
agreement with us that starts the 5 year term of coverage at the time
the aircraft is certified and delivered to the purchaser. Due to this
arrangement I am still seeing items from time to time that have
experienced failures directly traceable to the water based flux
'experiment' of 2001-2002.
For those people who are familiar with rosin flux soldering I would
still recommend the No Clean products, as the flux viscosity and
activity are almost identical to the rosin flux products, especially at
soldering temperatures. The No Clean flux does not tend to burn and
darken like rosin flux unless the iron temperature is set way too high.
This is of course my own experience and opinion with the water based
flux. Your experience may be (and I hope is) different.
These opinions do not represent the official position on my employer.
73 de AD5FU - John in Little Rock
Philip Covington wrote:
> On 8/19/06, John Nordlund <jnordlund at earthlink.net> wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>>
>>
>>
>>
>> Hi all,
>
> Which manufacturer's water soluble flux did you use back in 2001 - 2002?
>
> Phil N8VB
>
>
1156034815.0
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