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

Sat Aug 19 01:48:58 PDT 2006

Hi all,

I thought I might chime in and confuse all of you solder slingers just a 
bit.

Water based fluxes do work to a point, but there are some other options 
you might want to consider.

In the manufacturing facility I work at we tried the water based flux 
back in 2001 and 2002.  What we gained in cleanup convenience was lost 
quickly in the rather dramatic increase in solder fault related failure 
of finished products.  In the end we decided that there was no benefit, 
and a serious liability in using the water based flux products in our 
production process.  I was working at that time as an inspector of 
sub-assemblies and the drop in the quality of the solder joints that I 
examined under the microscope during this experiment was to say the 
least, 'alarming.'

In my current capacity as the quality data analyst that writes reports 
to our customers about the units returned for warranty service, I am 
still writing reports for units that failed due to the water based 
solder flux used during that period, and the inferior solder joints that 
were formed by trained and certified production staff.

In the end my company switched to another class of flux products 
referred to as "No Clean Flux."  Our solder is made by Kester and is an 
industry standard 63/37 alloy.  We use in the plant both a liquid flux 
and a rework paste flux also made by Kester that is rated as "No 
Clean."  What this designation means is that the flux residue if left on 
the circuit boards will not cause corrosion of the board traces.  This 
chemistry is approved by the FAA for use in aircraft electronics we 
manufacture.  As a result of the change in solder chemistry our warranty 
return rate is now under 2%, down from the 18% that we experienced with 
the water based fluxes.  If it is desired to remove the flux from the 
board, an alcohol wash with a disposable paintbrush with real hair 
bristles will remove flux residue without causing ESD hazards to the 
exposed components.

The No Clean flux behaves in a manner that is almost exactly the same as 
the old rosin flux most of you have used.  It does not boil off the 
board like the water based flux is prone to do.  The flux only helps the 
soldering process if it stays in the joint while the solder alloy is 
flowing into the joint.

I can't speak for anyone else, but I want my build of the boards in this 
project to be of the highest possible quality, and to not be subject to 
failures at odd intervals due to hidden solder joint faults.  Based on 
my experience with water based flux in soldering I can not recommend 
them to anyone for a project you want to get the best performance and 
service life out of.

I do recommend kester brand solder and flux  "No Clean"  type only.

DigiKey part Numbers follow:

Solder 'No Clean" flux core 1lb. roll     KE1523-ND

Rework Flux 10 gram syringe   KE1806-ND

Solder paste  "No Clean" flux  35 gram syringe   KE1507-ND 

For cleaning this flux (if you feel the need to do so) use denatured 
alcohol (ethanol) available at any home improvement center, or if you 
can get it pure isopropanol (not the 70% stuff they sell in the drug 
stores) on a natural hair bristle paint brush.

Thanks for reading..

73 de AD5FU in Little Rock    

aka

*John Nordlund
Quality Data Analyst
Audio International
Phone: 501.801.0652
Fax: 501.955.2988*

*_JFNordlund at DAHX.Com_* <mailto:JFNordlund at DAHX.Com>

Don AE5K wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Philip Covington wrote:
>
>   
>> On the subject of flux:  The best advise I can give is to throw away
>> your rosin based flux and solder.  Get a gallon of  Kester 2331-ZX
>> Water Soluble Soldering Flux and some 0.015" Kester "331" Organic
>> Water Soluble Flux core solder (63/37).
>>
>> Flux:
>> <http://www.philcovington.com/HPSDR/TOOLS/flux.JPG>
>>
>> Solder:
>> <http://www.philcovington.com/HPSDR/TOOLS/solder.JPG>
>>
>> Some people laugh when they see the gallon of flux (comments like: you
>> have 20 years supply there).  I laugh at those people when I hear
>> about them pulling up pads and traces with their solder wick.
>> Obviously they don't know that they are not using enough flux.
>>
>> The water soluble stuff literally cleans up with running water.  No
>> scrubbing, no smelly chemicals...  Try it - you'll like it..
>>     
>
> OK, I'm one of those who asked if you had enough ;-)  but you've
> convinced me.  WHERE did you buy your gallon?  I don't see it at either
> Digi-Key or Mouser, so if you have a source suggestion, let's hear it.
>
> Maybe I should put some of this info on the wiki FAQ too to help build
> our knowledge pool.
>
> Also source and details on the cheap syringes too.  I've never been
> "into" syringes except some years ago when I had a bunch of dogs that I
> gave shots to.
>
> The gallon of flux is too much for me so I plan to divvy it out to other
> ham builders in the 4SQRP group sometime when I meet with them again.
>
> Thanks,
> Don AE5K
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