How LEDs are Made • Hacker News Board

Re: How LEDs are Made

#21

Post by DigitalJack » Fri, May 30, 2014, 4:25 PM UTC

carrigan wrote: post #14

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.

this is a good link, although still high level: http://www.edisontechcenter.org/LED.html

and a lab to get a better feel for how band gaps affect the spectrum: http://electron6.phys.utk.edu/phys250/Laboratories/Light%20e...

Re: How LEDs are Made

#22

Post by [deleted] » Fri, May 30, 2014, 4:27 PM UTC

coreymgilmore wrote: post #4

Very surprising how manual this is, unless this is just for the purpose of showing how the LEDs are made. I would have expected everything in this process to be automated since electronic component manufacturing is very high volume. Also amazing how small the components (LED dies) are.

[deleted]

Re: How LEDs are Made

#23

Post by gipp » Fri, May 30, 2014, 4:27 PM UTC

leoedin wrote: post #2

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 used to work as a lab tech at one of the leading US LED manufacturers, and automated tools most definitely exist for all the steps pictured here (and they were typically done in a cleanroom, as well). Can't speak to what was done in China, though.

Re: How LEDs are Made

#24

Post by [deleted] » Fri, May 30, 2014, 4:33 PM UTC

DanBC wrote: post #16

HeyLaughingBoy wrote: post #12

Earlier quoted context omitted.

I'm not so sure. Let's assume you're paying someone $15/hour and she actually costs you $25/hour. Assuming a 10 minute break every hour (that's gotta be tiring work and you want to hold onto your employees), then that's 2500/(80 * 50) = 0.625 cents of labor cost per LED. I don't know what all the other costs are, but that one operation seems surprisingly cheap.

I'm stupid. EDIT: I am! Thanks for the corrections!!

[deleted]

Re: How LEDs are Made

#25

Post by johnohara » Fri, May 30, 2014, 4:37 PM UTC

DigitalJack wrote: post #21

carrigan wrote: post #14

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.

this is a good link, although still high level: http://www.edisontechcenter.org/LED.html and a lab to get a better feel for how band gaps affect the spectrum: http://electron6.phys.utk.edu/phys250/Laboratories/Light%20e...

Good links indeed. And interesting. Thank you.

Re: How LEDs are Made

#26

Post by chrisBob » Fri, May 30, 2014, 4:46 PM UTC

jmpe wrote: post #7

mrfusion wrote: post #6

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)

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.

Re: How LEDs are Made

#27

Post by gcb0 » Fri, May 30, 2014, 5:02 PM UTC

HeyLaughingBoy wrote: post #12

leoedin wrote: post #2

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'm not so sure. Let's assume you're paying someone $15/hour and she actually costs you $25/hour. Assuming a 10 minute break every hour (that's gotta be tiring work and you want to hold onto your employees), then that's 2500/(80 * 50) = 0.625 cents of labor cost per LED. I don't know what all the other costs are, but that one operation seems surprisingly cheap.

those salaries are 10% more than a target employee in california and 60% over a wallmart employee.

so i think the costs per led are even lower...

Re: How LEDs are Made

#28

Post by jmpe » Fri, May 30, 2014, 5:08 PM UTC

chrisBob wrote: post #26

jmpe wrote: post #7

Earlier quoted context omitted.

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)

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 almost dumped the idea for LEDs because of all the issues to deal with the exotic materials.

Re: How LEDs are Made

#29

Post by HeyLaughingBoy » Fri, May 30, 2014, 5:19 PM UTC

gcb0 wrote: post #27

HeyLaughingBoy wrote: post #12

Earlier quoted context omitted.

I'm not so sure. Let's assume you're paying someone $15/hour and she actually costs you $25/hour. Assuming a 10 minute break every hour (that's gotta be tiring work and you want to hold onto your employees), then that's 2500/(80 * 50) = 0.625 cents of labor cost per LED. I don't know what all the other costs are, but that one operation seems surprisingly cheap.

those salaries are 10% more than a target employee in california and 60% over a wallmart employee. so i think the costs per led are even lower...

Like I said, you want to hold onto your employees for more than a week ;-)

Re: How LEDs are Made

#30

Post by HeyLaughingBoy » Fri, May 30, 2014, 5:24 PM UTC

DanBC wrote: post #18

joezydeco wrote: post #11

Earlier quoted context omitted.

Everyone else has moved on to 0402-sized surface mount LEDs a long time ago. Could this manual process just be because nobody is building the old through-hole LEDs in massive quantities?

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!