Archived posting to the Leica Users Group, 2001/03/26

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Subject: [Leica] RE: chips
From: Jim Brick <>
Date: Mon, 26 Mar 2001 15:07:25 -0800

At 04:20 PM 3/26/01 -0500, you wrote:
>> Almost all the production CCDs have defective "dead"
>> pixels, and - sort of like cutting a diamond - Kodak
>> would cut up the wafer to produce the most efficient
>> mix of usable chips.

>I don't believe that's quite right.  Wafers have a number of the 'dies' on a 
>single wafer, typically in an XY grid pattern, like a checker board.  Some 
>of these individual dies typically do have defects.  Each of the individual 
>dies has what's called 'bond out pads', which are used to connect the wires 
>between the die and the chip carrier (typically ceramic or plastic mounting 
>holder that has the larger pins on it that goes into the ciruit board).
>The size of the individual die, is the size of the individual do 
>not get a larger usable array by, say, cutting the wafer such that four of 
>the dies are together...they would have gaps bewteen the dies, and bonding 
>to the pads between the dies would be most impossible, especially for an 
>imaging would have to cross over the image path.
>Also, you can't cut into the middle of a die, there is no place to bond out 
>to then...  I know it's quite technical, but I believe you relayed the story 
>a little off kilter.

Whomever this is... (Austin?) is correct.