I've always wondered, why do these chips have extra bits at the corners?

[XOIIO]

I was watching a teardown dave was going and saw this chip and it reminded me, I've always wondered why some chips have the extra bits sticking out of the corners while most do. Is it perhaps so that they can sell the sockets for them as well to make more money? That's the only thing I can think of, though those style chips don't really use sockets.

[w2aew]

I was watching a teardown dave was going and saw this chip and it reminded me, I've always wondered why some chips have the extra bits sticking out of the corners while most do. Is it perhaps so that they can sell the sockets for them as well to make more money? That's the only thing I can think of, though those style chips don't really use sockets.

Personally, I think it is to provide protection for the leads when they are in the carriers or tape, so that the leads aren't bumping into the edges of the cavity they're sitting in and possible get bent.  The extended corners keep the leads from touching the side of the carrier.

[XOIIO]

I was watching a teardown dave was going and saw this chip and it reminded me, I've always wondered why some chips have the extra bits sticking out of the corners while most do. Is it perhaps so that they can sell the sockets for them as well to make more money? That's the only thing I can think of, though those style chips don't really use sockets.

Personally, I think it is to provide protection for the leads when they are in the carriers or tape, so that the leads aren't bumping into the edges of the cavity they're sitting in and possible get bent.  The extended corners keep the leads from touching the side of the carrier.

Ah, that does make more sense, especially since it is more common on finer pitch IC's

edit: also wondering if there is a specific term for this.

[mwilson]

edit: also wondering if there is a specific term for this.

Looks like there's a Wikipedia article on quad flat packages (http://en.wikipedia.org/wiki/Quad_Flat_Package) that mentions this. Based on that I'd call those extra bits "bumpers."

[w2aew]

edit: also wondering if there is a specific term for this.

Looks like there's a Wikipedia article on quad flat packages (http://en.wikipedia.org/wiki/Quad_Flat_Package) that mentions this. Based on that I'd call those extra bits "bumpers."

Quoting from that wiki page: " A clear variation is Bumpered Quad Flat Package with extensions at the four corners to protect the leads against mechanical damage before the unit is soldered."

[XOIIO]

Alright so I guess bumpered is the term, cool.

[Shock]

Also you can't socket mount it.
You might not be able to mount a logic debugging clip as easily on it.

Without modifications of course.

[XOIIO]

Also you can't socket mount it.
You might not be able to mount a logic debugging clip as easily on it.

Without modifications of course.

Yeah, the socket idea basically came from thinking that maybe it was used on older chips that were socketed so that the company could sell sockets as well and it just stuck around as newer chips were made.

[tszaboo]

Yeah, the socket idea basically came from thinking that maybe it was used on older chips that were socketed so that the company could sell sockets as well and it just stuck around as newer chips were made.

The chip manufacturer/packager/designer usually never sells sockets. Have you seen any TI, or Analog Devices branded socket?

[XOIIO]

Yeah, the socket idea basically came from thinking that maybe it was used on older chips that were socketed so that the company could sell sockets as well and it just stuck around as newer chips were made.

The chip manufacturer/packager/designer usually never sells sockets. Have you seen any TI, or Analog Devices branded socket?

I've never really looked at socket brands before lol.