[sdiy] 4x4 Button Pads bulk order

Tom Arnold xyzzy at sysabend.org
Thu Jan 15 01:01:48 CET 2015


On Wed, Jan 14, 2015 at 11:38:05AM -0800, MTG wrote:
> Hi,
> 
> So the plan is to make a PCB of your own that accepts these? Have you 
> tried the PCB "extensively". Reason I ask is although these and the 
> Sparkfun items interest me, I'm concerned about the longer term 
> reliability of using them with a tinned solder contact. Shouldn't it be 
> gold or something on the PCB end?  I'm just asking here as it's not my 
> area of expertise. But I am, along with many of us, experienced with 
> rubber contacts not working after a period of time.  Are Livid and 
> Tenori, etc. doing it a certain way to enhance reliability?

I'll be doing a layout for my own project at some point.  Most likely I'll
just get the whole board done ENIG and see how that holds up.   Thats
usually a thin "soft" gold plating and a "hard" gold plating like is
traditional for card edge connectors would be much better.  Just have to see
how it does. 

I wouldn't do these in Tin if only because HASL tends to be a little lumpy (
look at it under a scope ).  ENIG is typically as flat as the copper
underneath.

One thing about "old" rubber contacts, they were the carbon pill type.
Quite scary how long I've actually fought with those in devices doing
repair.  The general consensus from Matsushita about 25 years ago was that
most of the problem was caused by the pill itself releasing mold release
compound over time.  In theory the more modern silicone+conductive printing
*should* last much longer.

I took apart many a cordless phone to clean that problem back when people
actually got devices repaired...

-- 
 -----------------------------------------------------------------
 - Tom Arnold       -  Free Synth DIY webspace http://www.sdiy.org 
 - SynthGeek        -  "...is it a virus, a drug, or a religion?"
 - K6AET            -  Juanita Shrugs. "What's the difference? 
 --------------------         -- Neal Stephenson,  Snow Crash



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