On Tue, 07 Dec 2010 09:26:16 -0500, Tony Miklos wrote:

On 12/6/2010 8:29 PM, zzzzzzzzzz wrote:
On Mon, 06 Dec 2010 17:14:47 -0500, wrote:

On Sun, 05 Dec 2010 23:38:31 -0600, "
wrote:

On Sun, 05 Dec 2010 22:41:14 -0500, wrote:

On Fri, 03 Dec 2010 18:44:24 -0600, "
wrote:



Claire is a moron.
I don't know who this Claire is - might well be a moron.

Misspelled, *that* wasn't intended as a slight.

However,
This from an expert:
Traditional tin-lead materials are not compatible with lead-free
device finishes.

Other than BGAs, one doesn't reflow the part, dummy. The solder paste gets
reflowed. ...and once again, we were talking about *repair*.



Because proper reflow for lead-free materials can
only be achieved with higher temperatures, attempting to process
lead-free terminated devices in 183?C tin-lead conditions leads to
incomplete wetting and the related issues of voiding and opens.

Wrong. As long as the solder paste is appropriate, it doesn't much matter
whether the part is tin, tin-lead, or gold (or any other commonly used finish)
tin-lead solder will wick just fine. ...better than lead-free solder will on
the same parts, in fact.

Doug Dixon, Global Marketing Director
Henkel Corp
Mr. Dixon has been in the electronics field for over twenty years and
is the Global Marketing Director with the electronics group of Henkel.
Prior to joining Henkel, he worked for Raytheon, Camalot Systems, and
Universal Instruments.

You can't read.

I'll take his word over someone ( a usenet engineer) who fudges his ID
on usenet.

Yes indeed, who would believe a Usenet liar, like Clare?

And another expert agrees:
Many of the components manufactured in the last few years have been
lead free, especially surface mount chip components as they are Tin
plated.

Indeed, almost all *are* tin plated.

Can you solder these with 60/40 tin/lead solders, the answer is yes
and millions of solder joint have been soldered this way for years.
The problem however is some of the Lead-Free component plated RoHS
components have a SAC alloy for a lead coating and this is the issue.

The 60/40 alloy will not be hot enough to melt the SAC alloy to create
a sound joint. Yes, many papers have been are being published stating
that this will work, but keep in mind the thermal profile and the
length of time the solder joint needs to be above the reflow
temperature to all complete dissolution of the Tin/Lead into the SAC
alloy coating or solder balls on the components. This is much
different than what was used to the low temperature Tin/Lead alloys
and dwell times above the reflow temperature is going to have to
increase to create a sound solder joint.

Nonsense. It works fine.


Untill it doesn't.
Leo Lambert, Vice President, Technical Director
EPTAC Corporation
At EPTAC Corporation, Mr. Lambert oversees content of course
offerings, IPC Certification programs and provides customers with
expert consultation in electronics manufacturing, including RoHS/WEEE
and lead free issues. Leo is also the IPC General Chairman for the
Assembly/Joining Process Committee.

Again, I'll take the word of an acknowleged expert in the field over
that of the unknown usenet engineer.

If you are 100% certain your RoHS compliant components have tin
coating, you CAN use leaded solder.

They *all* are. Yes, I have checked all of our parts because that's part of
what I do.

Back to the original point, *REPAIR*. Leaded solder is just fine to repair
RoHS gizmos.

If you are just ASSuming all RoHS compliant components have tin coated
leads, you are treading on extremely thin ice.

Clueless Clare.

I have stated that using leaded solder with RoHS compliant components
is "not best practice" and can lead to product failures.

Again, clueless. Repairing RoHS boards with leaded solder is, in fact, better
than using lead free precisely because of the difference in temperatures and
better wetting.

I'm not saying you can't get away with it some or most of the time -
I'm saying it is not correct, and it is wrong and dangerous to say it
is "safe" or "proper" to solder RoHS compliant components with regular
lead-based solders.
Recommending it is not being responsible, without at least adding the
possibilities of the "gotchas" which are well documented and
recognized by the experts, and which I have provided cites for.

Clueless Clare backpedals more.


No backpdaling at all.

Bull****.

I said in the beginning you will often get away with it, but it is
not the "recommended" way, it is not "best practice" and in some cases
it WILL bite you.

The subject was repair, Clueless Clare.

In your case you have double checked and all your components are tin
coated leads, so for you it will work.
Some components are NOT tin coated, and those can cause problems.

Exceedingly rare (never saw one). Some are gold flashed, which is peachy,
too.

A few weeks ago I installed a couple of 35 amp bridge rectifiers. The
leads were, as they often are, blackish colored and do not tin very
well. Seems they always come that way, even from different
distributors. They always get hand cleaned with the same brass wool I
use for the soldering iron before being installed.

It sounds like these are contaminated. Any abrasive cleaning can damage the
plating and could *easily* cause problems down the road. We used to call
these sorts of things "solder proof" leads. It was generally because the
stock was old.