LM393A: Are there any rules for judging the finish of component lead tips?

Katsumi Miyashita

Part Number: LM393A

Thank you for all your support.
Please advise me.

My company inspects the finish of component lead tips on TI products purchased from non-authorized channels.
However, I am always troubled by how to judge whether it is good or bad.

I compare them with those purchased through the authorized store route, and if I find any difference in the lead finish, I judge them as defective.

The lead finish of Sample No. 2 was judged to have corroded plating. Is my company's judgment correct?

Are there any good/bad rules for the finish of component lead tips?

If so, please tell us how to judge it.

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 243000 points

Some TI parts use deliberately roughened leadframes; see [FAQ] Why do the leadframes look strongly oxidized or corroded?

0 kai klaas69 over 2 years ago

Guru 140200 points

Hi Katsumi,

maybe this FAQ answers your question?

https://e2e.ti.com/support/logic-group/logic/f/logic-forum/718449/faq-why-do-the-leadframes-look-strongly-oxidized-or-corroded

Kai

0 Paul Grohe over 2 years ago

TI__Mastermind 49856 points

Hello Katsumi,

As Kai and Clemens have pointed out, the roughened leadframe can look corroded because it is not "shiny" as we are accustomed to. The leadframe is copper and is plated with NiPdAu. The ends of the leads can look "green" due to refraction.

I can confirm that the LM393APW is available in a roughened leadframe.

What you are seeing is normal for roughened devices.

0 Katsumi Miyashita over 2 years ago in reply to Paul Grohe

Prodigy 55 points

Hi Clemens, Kai, and Paul,

Thanks for the quick reply. It is very helpful.

I will share about the responses I have received from you guys in my company. Appreciate it.

However, my company has a problem.
We believe that TI products purchased from non-authorized sources are poorly stored and the leadframes appear to be oxidized or corroded.
Also to think that bad brokers reworked the inferior ones in order to sell them for a higher price.

Can you please advise if you have any good solutions?

I don't think I should consult this TIE2E design support forum every time I want to know if the plating is good or bad.

0 Paul Grohe over 2 years ago in reply to Katsumi Miyashita

TI__Mastermind 49856 points

Hello Katsumi,

I am not aware of any "standard" or appnote on determining corrosion progress.

Authorized TI distributors will ship the devices in a sealed ESD bag containing a desiccant strip and humidity indicator strip.

You will just have to compare to known good devices - properly stored. But beware that the roughened lead frame can appear within the same shipment.

TI will not support devices not sold by authorized TI distributors (just have to say that).

For more packaging onfo:

https://www.ti.com/support-quality/environmental-info/packing-material-information.html

https://www.ti.com/support-packaging/SMT-application-notes.html

0 Katsumi Miyashita over 2 years ago in reply to Paul Grohe

Prodigy 55 points

HI Paul,

Thank you very much for your prompt response.

I understand that it is difficult to determine the progress of corrosion and that TI does not support equipment that is not sold by an authorized distributor.

If any more cases arise, i would like to ask for your advice.

Thank you in advance for your cooperation.

0 Paul Grohe over 2 years ago in reply to Katsumi Miyashita

TI__Mastermind 49856 points

Hello Katsumi,

You can, but we would just be "eyeballing" it just like you through photos, and any determination would not be anything official. As I said previously, you should have a 'standard" set of "known good" devices to determine any corrosion.

At minimum, the device rails/reels should be in (preferably vacuum) sealed bags to protect from moisture.

Amplifiers

Amplifiers forum

LM393A: Are there any rules for judging the finish of component lead tips?