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Earlier quoted context omitted.
For people who don't know 0402 is: > 0402 (1005 metric): 1.0 mm × 0.5 mm (0.039 in × 0.020 in).
And they suck to do manually. I started this morning off by hand-stuffing some PC boards with (among other parts) 19x 0402 resistors per board. There was a reason I did it before I had any coffee!
I'm surprised by how manual the whole process is. I think labour is so expensive in the west that any manufacturing of small low value items is incredibly highly automated (see youtube for lots of videos of how huge automated production lines work). There's no way you could employ someone to manually bond 80 LEDs a minute in the west and still have a competitive product.
I don't envy the eyesight of the worker that has to look through a microscope their entire shift, this was sad to read.
I could do this in my basement! Years ago I answered a "for sale" newspaper ad for used office desks and some test equipment. I showed up at the address and it was a small dingy old building and most of the employees seemed to be 55+ year-old women. When I asked what they did and was told they made diodes, you could have knocked me over with a feather. Like he did, I assumed that all electronics parts manufacturing w…
The title here is slightly misleading- this isn't how LEDs are made, it is how LED dies are packaged. The more difficult part of all of this is creating the dies themselves, which is requires a clean room and all the automated tools I'm sure most people here were expecting to see.
Then you have the actual crystal growth portion where you shove all those wafers into an evacuated chamber, heat them to a thousand degrees, spin them around, and spray them toxic pyrophoric gases. This process takes multiple hours to grow just a few microns of light producing crystals.
Then you have to grind the wafers down to the appropriate die thickness, go through multiple stages of etching, add a phosphor for white LEDs, deposit gold and ITO for electrical contacts, and use lasers to cut them into individual die. Then, finally, you can ship them to the people in the linked article. Honestly, this article is the most boring part of the whole process.
Source: I used to work in R&D for an LED manufacturer.
This is clearly an old process - when was the last time you saw a 7-segment display, or those big red round thru-hole LEDs, outside of hobby electronics? I'd be very curious to see how this process differs from the high-power lighting LED manufacturing process (e.g. CREE), which is a more modern technology by several decades. I would guess there is much more of the automation people are expecting...
Every HP common slot server PSU has one of those round through hole LEDs on it. I have an HP server sitting here (DL580) that has two 7 segment displays on its motherboard. These things are definitely still used in modern products.
I'm surprised by how manual the whole process is. I think labour is so expensive in the west that any manufacturing of small low value items is incredibly highly automated (see youtube for lots of videos of how huge automated production lines work). There's no way you could employ someone to manually bond 80 LEDs a minute in the west and still have a competitive product.
Earlier quoted context omitted.
Your reasoning for the 2" wafer surprises me because most semiconductor work scales well, and the cost to buy and process larger wafers is only slightly more expensive while the surface area is much larger. A 6" wafer is 9 times as big as a 2" one.
A 6" wafer will also have lots of dies on the edge that don't pass automatic testing. Don't forget that most devices are located near the edge. Secondly, upgrading your Fab to switch your process to larger wafer size has a 10-figure $ price tag. It's not trivial for digital, let alone opto electronics. LEDs are special in that they deviate severely from the standard mos process. When Monsanto first produced them they…
I don't understand this. Given a fixed size die, the number of dies near the edge would go up linearly as the wafer size goes up. The number of interior dies would go up quadratically.
I could do this in my basement! Years ago I answered a "for sale" newspaper ad for used office desks and some test equipment. I showed up at the address and it was a small dingy old building and most of the employees seemed to be 55+ year-old women. When I asked what they did and was told they made diodes, you could have knocked me over with a feather. Like he did, I assumed that all electronics parts manufacturing w…
Making transistors at home from silicon wafers: https://www.youtube.com/watch?v=PdcKwOo7dmM
I am sure if I thought about it I would have realized that it is just support for the silicon. I guess I never thought about it that much until today.
I wonder how the LED dies are made?
Same as regular chips: in a grid on a wafer, then cut and pick&placed. Don't forget: yield goes up when the die shrinks because the defects are typically small spots. The smaller the die the better you pixelate the defects. The wafers are only 2 inch diameter to avoid yield loss due to edge effects: at the edge of the wafer you have lowest quality components (optical ring effects)