[hpsdr] [Fwd: Re: Flux sources? Some other ideas..]

[John Nordlund]

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
>
>

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