Rich Grise wrote:

On Tue, 05 Jun 2007 14:20:25 -0400, Tom Del Rosso wrote:

"Rich Grise" wrote in message
news
On Mon, 04 Jun 2007 21:31:10 -0400, Tom Del Rosso wrote:

"Jim Thompson" wrote
in message

Back in my discrete days I used copper eyelets for connecting large
gauge high current wires.

The military balk because the solder _under_ the eyelet can't be
inspected.

People always say they crack more, even if they're good initially.
I don't know why that's so.

Vibration. The solder work-hardens and makes the joint unreliable.

But why is that different from any other joint?


It's the metal sandwich of the pad, solder, and eyelet surface - when
the eyelet moves relative to the board, it puts a shear stress on the
solder. "Ordinary" joints don't have that problem because the solder
isn't squashed between two metal surfaces.

Well, it sounds good to me. ;-)

Cheers!
Rich

Definitely, mechanical stress seems to enhance or aggrivate the
migration of the solder.
Monitors exhibit similar problems; one or more colors get
intermittent and / or go out.
One then must re-solder the CRT socket to the PCB.
The mechanical stress comes from the sponge in the back of the case
that presses on the metal cage around that PCB.
I have fixed dozens of monitors that way, some 2 or three times.
The one i have was bought 12-15 years ago and fixed 3 times so far.
I have called it electomigration, because of the metal flow patterns
with regard to presumed current flow in each trace.