LM4780TA (Non Insulated Type)

JustinMarker · 08:02 PM

hi guys,
take look at the back of the chips (LM4780TA)
the metal plate seem tarnish. is this normal?

same goes for LM4702CTA

thank you.

JustinMarker · 7th April 2011, 08:24 PM

shoudl be more careful with word.
i mean non-isolated

TheLaw117 · 7th April 2011, 08:44 PM

I doubt anything is wrong with them. As long as you got them from a legit supplier that you know supplies authentic chips, don't worry about it. I have plenty of ICs laying around with similar "tarnish". If it's bothering you, get some rubbing alcohol and a Q-tip.

TheLaw117 · 7th April 2011, 08:49 PM

Though the casing on the second ones do look a little odd...

JustinMarker · 8th April 2011, 12:41 AM

hi,
yes i got it from a legit supplier locally.
thanks for the assurance.

the casing on the second one are from LM4702CTA.

anyone from the semiconductor packaging industry please do help to comment from the manufacturing point of view.

thank you.

pmbrunelle · 8th April 2011, 04:36 PM

I wouldn't try much aggressive cleaning of the heat transfer surface.

If you're going too aggressive with sandpaper or a file or something, while you'll make the surface shiny, it's easy to take off more material from the edges, and make a convex surface with less effective heat transfer area.

Maybe some steel wool, but it looks pretty normal to my eye.

7th April 2011, 07:45 PM	#1
JustinMarker diyAudio Member Join Date: Jul 2004 Location: Singapore	LM4780TA (Non Insulated Type) hi guys, take look at the back of the chips (LM4780TA) the metal plate seem tarnish. is this normal? same goes for LM4702CTA thank you. Last edited by JustinMarker; 7th April 2011 at 08:02 PM.

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7th April 2011, 08:24 PM	#2
JustinMarker diyAudio Member Join Date: Jul 2004 Location: Singapore	shoudl be more careful with word. i mean non-isolated

7th April 2011, 08:44 PM	#3
TheLaw117 diyAudio Member Join Date: Sep 2010	I doubt anything is wrong with them. As long as you got them from a legit supplier that you know supplies authentic chips, don't worry about it. I have plenty of ICs laying around with similar "tarnish". If it's bothering you, get some rubbing alcohol and a Q-tip.

7th April 2011, 08:49 PM	#4
TheLaw117 diyAudio Member Join Date: Sep 2010	Though the casing on the second ones do look a little odd...

8th April 2011, 12:41 AM	#5
JustinMarker diyAudio Member Join Date: Jul 2004 Location: Singapore	hi, yes i got it from a legit supplier locally. thanks for the assurance. the casing on the second one are from LM4702CTA. anyone from the semiconductor packaging industry please do help to comment from the manufacturing point of view. thank you.

8th April 2011, 04:36 PM	#6
pmbrunelle diyAudio Member Join Date: Sep 2005	I wouldn't try much aggressive cleaning of the heat transfer surface. If you're going too aggressive with sandpaper or a file or something, while you'll make the surface shiny, it's easy to take off more material from the edges, and make a convex surface with less effective heat transfer area. Maybe some steel wool, but it looks pretty normal to my eye.

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