[Elecraft] Re:IC Sockets versus Non-sockets

[Ed Tanton]

Well-l-l-l... I guess this is my week to be disagreeable. I used IC sockets 
all over my Field-Test K2, and have not had the slightest problem. I DID 
use socketless IC pins for a couple of the RF ICs, but otherwise used 100% 
top-grade machined-pin, gold-insert sockets.

The real difference is the temperatures and static involved. If you have a 
pretty good hand, totally-static-safe soldering iron, then it's probably a 
toss-up. But w/o sockets, any heat-excess or static is going to affect an 
IC sooner or later.*1

I have a pretty good hand (700 degrees/quickly in & out*2) and my iron is a 
Weller EC-2002... which is pretty good about static. But still, 
I-conservatively-greatly prefer to use sockets. And even though you can 
certainly troubleshoot w/o removing an IC, it's a LOT easier to swap than 
it is to poke around.

Also, you're correct about THE way to remove a soldered-in IC: clip it out. 
But a caution follows: BOTH solder-suckers and solder-removal-braids have 
their associated problems: a) solder-suckers splash solder flecks for 
amazing distances from the removal site AND create serious disturbances in 
the Force young Skywalker-unless they are the non-static-producing types; 
and b) solder-removal braid not only seriously abrades-or otherwise 
removes-the plating on modern solder tips (such that no amount of tinning 
will replace it) BUT it also can sufficiently heat the bonding adhesive 
between a pcb pad or trace so as to lift it-and there's no bonding it back 
down w/o a special kit.

That said, sooner or later, you'll probably have to use them both. 
Reluctantly every time, so have I.

So I'll keep on using my sockets until something won't work... THEN we'll 
see how good I am with the EDSYN hot-air SMT 'iron' I have-'cuz that's the 
only way you'd ever get an IC socket out-hopefully w/o ruining the pc board.

*1) Electron micrographs show some interesting defects caused by static. 
The at least micron-fine IC traces are literally exploded by the equally 
minute current the static charge provides. Worse, sometimes, they are NOT 
blown fully... but reduced by 25% to 75% and eventually  open. Might be a 
day... might be a week... no way to predict. That's the real reason for 
careful handling of static-sensitive ICs. In the worst case they DON'T 
die... for a while. Probably a CONTEST weekend.

*2) I once handbuilt-from a $500 bare DTC motherboard-a PC-XT. Very 
familiar to me at the time was a bad experience maintaining the KIM-1s in 
an Engineering School computer lab that had no air conditioning (hard to 
believe isn't it?!!) Because of the temperature extremes in the summer, I 
had to make once or twice daily trips through the lab and reseat EVERY 
tin-lead IC in EVERY tin-lead IC-socket in the 20 or 30 microprocessor 
trainers they had. (A thin layer of oxide would develop THAT frequently, 
insulating the ICs from the sockets.) So, getting back to my PC-XT, I used 
100% machined-pin sockets in it, and-wonder of wonders-the zillion 
IC-socket-pin joints were all good; and the board worked. I still have that 
unit, by the way. With its $1200 Hard-Card I was thrilled to get. And I 
never had a minute's trouble with any of the socket-IC interface.


73 Ed Tanton N4XY <n4xy@earthlink.net>

Ed Tanton N4XY
189 Pioneer Trail
Marietta, GA 30068-3466

website: http://www.n4xy.com

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