why are the die's in led's square?

Here we go a dumb arse kind of question, why are the die's square
were can they not be round ? answers on a post card i havn't got a clue england thanks DocD

I think it might have to do with getting as much out of a single wafer.

They can cut it round but then the material between the round cuts will be wasted.

You make lots of 'die' at once on a 'wafer' and then saw it up and package the sub-bits to as indevidual die. You could make the inards on the square die circular but your throwing away a good bit of area that could be producing light.

Ifor

Some chips are hexagonal, some are rectangular, but most are square.
Trying to make round chips out of a wafer would be hilariously difficult.
The process is similar to "cutting" glass; you make an "incision" and then you break it off. There's no actual cutting or grinding at this stage.

ok i get the cost, over mass production but for a very high end light's a round die would be a plus , better image but thanks for the info DocD

DocD said:

ok i get the cost, over mass production but for a very high end light's a round die would be a plus , better image but thanks for the info DocD

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How would a round die have advantages over a square die?

IIRC some of the older Luxeons were round.
RC

Note that sometimes due to the dome design on the LED sometimes the actual die size cannot be clearly distinguished without removal of the dome...and within that process, the destruction of that LED.

All 5mms are square [except the GS]
Luxeons have always been square, resting on a hexagon base
CREEs/SSCs have always been a square with two corners removed
OSTARs are awesome, but I really don't know how to describe it

Reima said:

IIRC some of the older Luxeons were round.
RC

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those probably weren't luxeons, they have always been square, I think your referring to the ones from optoelectronics [I think thats what its called...or was it osram:candle:].... they have the same emitter design as the luxeon. I'm out of town or I'll post some comparison pics

try here for now: https://www.candlepowerforums.com/threads/188772

Round wastes about 22% of the die as opposed to square. However, you can make hexagonal dies without waste if you want something closer to circular. With laser cutting this shouldn't be any more difficult or costly than square dies.

The gerber firecracker has a round LED.

Also, way too many apostrophes in the initial post and title.

Illum_the_nation said:

those probably weren't luxeons, they have always been square, I think your referring to the ones from optoelectronics [I think thats what its called...or was it osram:candle:].... they have the same emitter design as the luxeon. I'm out of town or I'll post some comparison pics

try here for now: https://www.candlepowerforums.com/threads/188772

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I have some old low dome Luxeons (taken out of the early Arc LS lights) that certainly look round (at least the phosphor is). MY camera doesn't take decent close ups other wise I would post some photos. Maybe I should take one apart to see if the die is round like the phosphor.
Remember the low domes were the ones with the purple tint.
RC

greenlight said:

The gerber firecracker has a round LED.

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I'm pretty sure I can see a square die under a round circle of yellow phosphor in that picture.

I took a low dome apart tonight, under the round phosphor is a square die.
RC

Reima said:

Remember the low domes were the ones with the purple tint.
RC

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low domes are of the "batwing" type, regardless of it being a lamertian or batwing the tint of the LED is not dependent on the dome type...it was purely bad luck that you got YA tinted low domes.

IIRC I have X1, YO, and I think a W0 tinted low dome LEDs somewhere in my toolbox

It's simple, you cut dice out of wafers with diamond saws that cut in straight lines. Semiconductor dice are almost universally rectilinear.