[Elecraft] K3S solder type?

[n9tf at comcast.net]

Hi Jer, 
  
Solder spidering, or "Tin whiskers" has always been an issue, even when 60/40 SnPb solder was the "standard". In the past decade, the switch to non lead, or RoHS compliant solders has, mandated the removal of Pb in solder. With the absence of Pb and a much higher content of Sn, typically 96.5% of the solder formulation, tin whiskering has become more of a taking point and in some cases, problems in micro and especially nano circuits. 
The typical formulation for solder paste (for reflow) and solder pots is 96.5%Sn, 3%Ag, and .5%Cu. It's the brighteners in the Sn that are crucial to midagate the tin whisker growth. 
Although I did not see anything on the Elecraft web site that stated RoHS compliant, I would bet that their PCBs are being soldered with this type of RoHS compliant material, as Elecraft is selling into the EU marketplace, where these restrictions are enforced. 
  
As far as tin whiskering issues for the type of PCB's that are designed into these products, I do not think one should fear and "shorting" issues due to tin growth, as the pad spacing and line spacing is not at a critical spacing. Tin whisker growth is a very slow process, and we humans will probably be gone before anything like that would present a problem, especially in the "normal" conditions we operate the gear. 
  
I would be more concerned about cold solder connections as the newer RoHS solders require higher temps to reflow. That too has pretty much been handled over time with pretty precise solder reflow apparatus, and tweaks over the years on the paste and solder formulations. 
  
73 Gene, N9TF  

----- Original Message -----

From: "Jerry Moore" <jermo at carolinaheli.com> 
To: elecraft at mailman.qth.net 
Sent: Wednesday, August 5, 2015 11:33:53 AM 
Subject: [Elecraft] K3S solder type? 

Anyone know the type of solder used in the K3S board manufacture? I've been 
reading up on environmentally safer solder and all of the reliability issues 
that result from the solder spidering over time. Anyone happen to know? 

I'm sure it's not an issue but it came to mind. I tried to call Elecraft to 
ask but they are busy helping customers who need actual help with their 
units J 

  

Jer 

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