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I don't know the name of it, but if you are looking for part names, try the teardowns on iFixits website.
 
Is your board the one below the metal shielding that the hand is holding in the picture you linked to ? If it is that board with all the electronics on it - it is the LCD control board. It can not be purchased alone though, as it is linked directly to the LCD via multiple paper-thin plastic cables. If you broke it somehow, you need to replace the entire LCD.
 
I am trying to get an Imac running without a screen. However I believe this board has a temp sensor connected to it. When this board is disconnected from the machine the machine runs ultra slow.
 
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