On Sun, 15 Jun 2008 20:33:38 -0700, Jeff Liebermann wrote:

On Mon, 16 Jun 2008 08:16:45 +0800, rebel wrote:

I think we're on the same side, but seeing things from a differnt point of view.

Maybe. Certainly additional reinforcement would be helpful. But that
will just create the situation I saw on much older (286/386/486)
generation laptops with the big parallel port connector. The plug and
cable was so stiff and the connector was certainly strong with all 25
pins soldered into the board. However, that didn't stop users from
literally cracking the PCB with pressure applied to the connector. It
wasn't until manufactories started reinforcing the DB-25S connector
with a metal backplate, that the boards stopped cracking.

A DB25 is mechanically a different story entirely, and I don't believe you can
apply the same results/observations to a two/three-pin power receptacle.


Certainly the manufacturers rely only on the solder to provide the mechanical
support - that is exactly why these failures are endemic.

Again, I beg to differ. When I do an autopsy on a broken power jack,
it's the plastic shell that usually fails, not the solder connections.
I commonly see them with the metal contacts and leads intact, but the
plastic shell totally destroyed. If the solder was weak, it would
pull the contacts out of the board.

We clearly have very different experiences then. Almost without exception, the
power inlets I have had occasion to repair have had the hardware intact and the
solder bonds separated, often with evidence of significant arcing.

Well, now that you mention it, I have seen one Acer Aspire 3000 laptop
where the connector lifted out of the board. However, it did that
intact because Acer forgot to solder the connector. There was no
solder on the pads.

I've seen some evidence of very_poor attempts at soldering, but none to date of
no solder.

One of my Acer laptops has a right-angle connector and has surviced for about
ten years of in-vehicle use.

I've seen adapters for right angle power connectors, USB connectors,
and possibly some others. It's a great compromise. I just replace
the power plug with a right angle equivalent, which is cheaper and
easier (for me).

The right answer is Magsafe connectors:
http://en.wikipedia.org/wiki/MagSafe

What would you recommend instead? I use 24 hour epoxy.

Yep, that's my preference if people have the patience.

I typically have a 3-4 day backlog. Tearing the laptop apart and
putting it back together usually takes at least 1-2 days. Somehow, it
always takes me twice as long to put it back together as it does to
take it apart.

Crikey, that's a lot of time to spend on each.

Overnight drying is mandatory. By the time the
customer gets it, the epoxy is dry. The trick is in the mixing. It
has to be exactly 50-50 or it will either not harden or fall apart.

Yep, been using the stuff since the '60s.

It doesn't matter whether they shrink/expand/whatever, they invariably seem to
cause some attempt at movement - and that applies mechanical stress to the
solder bond. If you glue first, then solder, that issue is avoided.

I have never seen that problem. Few connectors are flat on the PCB.
There are usually tiny bumps or spacers under the connector to allow
for flux removal. The connectors won't go through conventional hot
freon or IR soldering processes, and have to be hand soldered. The
bumps allow for some misalignment and movement. It might be a problem
with some connectors that I've never seen, but for the typical laptop
power connector, it doesn't matter. However, I will admit that I
always reflow the solder connection after gluing, mostly to make
absolutely sure I have a decent connection. That will take care of
any real or theoretical tensioning.