magnetizable LED leads

[Bernhard Kuemel]

I noticed the leads of a 5 mm white LED were magnetizable. I thought
they were tinned copper, but that's obviously not the whole truth. What
are they made of?

 

[Spehro Pefhany]

On Mon, 04 Jun 2012 10:23:10 +0200, the renowned Bernhard Kuemel
<bernhard@bksys.at> wrote:

I noticed the leads of a 5 mm white LED were magnetizable. I thought
they were tinned copper, but that's obviously not the whole truth. What
are they made of?

Sometimes they use steel (plated). Steel has much lower thermal
conductivity so it's not as good, but it is cheaper.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Fred Abse]

On Mon, 04 Jun 2012 10:23:10 +0200, Bernhard Kuemel wrote:

I noticed the leads of a 5 mm white LED were magnetizable. I thought they
were tinned copper, but that's obviously not the whole truth. What are
they made of?

Tin plated steel.

Some manufacturers' IC lead frames are the same, also transistor leads.

--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)

 

[Weland]

Tin plated steel.

Some manufacturers' IC lead frames are the same, also transistor leads.

Is there some hidden legitimate reason to this other than price? I was
under the impression that steel is not a very good option due to its
thermal properties.

--
weland@sdf.org
SDF Public Access UNIX System - http://sdf.org
% grep me no patterns and I'll tell you no lines

 

[Bernhard Kuemel]

On 06/04/2012 02:25 PM, Spehro Pefhany wrote:

On Mon, 04 Jun 2012 10:23:10 +0200, the renowned Bernhard Kuemel
bernhard@bksys.at> wrote:

I noticed the leads of a 5 mm white LED were magnetizable. I thought
they were tinned copper, but that's obviously not the whole truth. What
are they made of?

Sometimes they use steel (plated). Steel has much lower thermal
conductivity so it's not as good, but it is cheaper.

OTOH the silicon doesn't get as hot when soldered, I guess.

Bernhard

 

[Ian Field]

"Fred Abse" <excretatauris@invalid.invalid> wrote in message
newsan.2012.06.04.11.00.51.380550@invalid.invalid...

On Mon, 04 Jun 2012 10:23:10 +0200, Bernhard Kuemel wrote:

I noticed the leads of a 5 mm white LED were magnetizable. I thought they
were tinned copper, but that's obviously not the whole truth. What are
they made of?

Tin plated steel.

Some manufacturers' IC lead frames are the same, also transistor leads.

Pretty common on glass encapsulated signal diodes too apparently.

 

[Phil Hobbs]

On 06/28/2012 04:37 PM, Ian Field wrote:

"Fred Abse"<excretatauris@invalid.invalid> wrote in message
newsan.2012.06.04.11.00.51.380550@invalid.invalid...
On Mon, 04 Jun 2012 10:23:10 +0200, Bernhard Kuemel wrote:

I noticed the leads of a 5 mm white LED were magnetizable. I thought they
were tinned copper, but that's obviously not the whole truth. What are
they made of?

Tin plated steel.

Some manufacturers' IC lead frames are the same, also transistor leads.


Pretty common on glass encapsulated signal diodes too apparently.

Glass packages use Kovar leads, which are magnetic.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net