Author Topic: Optoelectronics - die pictures  (Read 845 times)

0 Members and 1 Guest are viewing this topic.

Offline Noopy

  • Frequent Contributor
  • **
  • Posts: 499
  • Country: de
    • Richis-Lab
Optoelectronics - die pictures
« on: September 18, 2020, 09:38:12 pm »
Hi all!


I need a topic for optoelectronic pictures.  8)

You can find the main page here:
https://richis-lab.de/Opto.htm


Today I have uploaded pictures of the 7 segment led display VQB17 built in the "Werk für Fernsehelektronik Berlin":






In a red cap there is a opaque foil above a white light shaper with a black textured surface.




You can see the LEDs through the light shaper.
...In the middle there is a loose bondwire...




To connect the pins to the board they used pressfit technology. Very cool!  :-+






The die is 310µm x310µm.
You can spot a MESA structure and a dark square. I assume the dark square is some highly doped contact area.








You can´t really recognize which part of the structure is glowing because the light spreads through the semiconductor and the protective coat all over the die surface.
It start´s glowing at 5µA.




The LED glows also at -12V (2,5mA)...  ;D
The light is much less uniform and of course a lot darker.


More pictures here:

https://richis-lab.de/Opto02.htm

 :-/O
« Last Edit: September 19, 2020, 06:59:44 am by Noopy »
 

Offline Noopy

  • Frequent Contributor
  • **
  • Posts: 499
  • Country: de
    • Richis-Lab
Re: Optoelectronics - die pictures
« Reply #1 on: September 24, 2020, 08:27:42 pm »
Let´s look inside a blinking LED:

https://richis-lab.de/Opto03.htm




You can´t burn the package stuff like epoxy mould. There is always some sticky dirt left. But you can take pictures through the package. The quality is a bit worse but it´s ok...




The "controller" is 0,48mm x 0,46mm the LED is 0,2mm x 0,19mm.






As expected there is a RC oscillator which frequency is divided with the help of 19 flip-flops.
And hey, the die has two outputs. It can be used to drive two LEDs alternating.
Since the outputs a current sources the not used output is connected to ground.




The current flowing into the LED shows that the second stage consumes nearly the same current as the first stage.
The blinking frequency is round about 1,2Hz.




You can see the oscillator frequency between the pins. The frequency is 0,59MHz. Devided by 19 you get 1,1Hz. That´s quite close to the 1,2Hz observed in the current flow. The frequency is not very stable.

 :-/O
 
The following users thanked this post: Zero999, Dave, edavid, SilverSolder, james_s, JackJones, sandalcandal

Offline Zero999

  • Super Contributor
  • ***
  • Posts: 14588
  • Country: gb
  • 0999
Re: Optoelectronics - die pictures
« Reply #2 on: September 24, 2020, 10:01:18 pm »
Thanks a lot.

What does Pre mean?

Presumably you don't need a series resistor for that particular LED? I always thought flashing LEDs still needed one.

Another thing which interests me is the maximum operating voltage is seldom mentioned on flashing LED datasheets. In another thread someone ran one off rectified 24VAC, so nearly 34V, via a suitable resistor, with no problems.
 

Offline Renate

  • Frequent Contributor
  • **
  • Posts: 618
  • Country: us
Re: Optoelectronics - die pictures
« Reply #3 on: September 24, 2020, 11:05:53 pm »
Looks nice.

Hey, what's your camera/optics/filters/polarization/lighting?
(I can't find any info on your website, auf Englisch oder Deutsch.)
 

Offline David Hess

  • Super Contributor
  • ***
  • Posts: 11906
  • Country: us
  • DavidH
Re: Optoelectronics - die pictures
« Reply #4 on: September 24, 2020, 11:11:35 pm »
I thought the old style blinking LEDs were fabricated as one chip.
 

Offline profdc9

  • Regular Contributor
  • *
  • Posts: 195
  • Country: us
Re: Optoelectronics - die pictures
« Reply #5 on: September 25, 2020, 02:30:33 am »
If you immerse the plastic in an indexing matching liquid such as glycerin (index of refraction 1.47) or corn syrup (index of refraction 1.53), you can make the bulb "disappear."  Then place a flat piece of glass like a watch glass or a microscope slide on top of the liquid and you should get a very good picture.

 
The following users thanked this post: BravoV, Noopy

Offline Noopy

  • Frequent Contributor
  • **
  • Posts: 499
  • Country: de
    • Richis-Lab
Re: Optoelectronics - die pictures
« Reply #6 on: September 25, 2020, 03:15:49 am »
What does Pre mean?

Pre stands for Predriver.


Presumably you don't need a series resistor for that particular LED? I always thought flashing LEDs still needed one.

Another thing which interests me is the maximum operating voltage is seldom mentioned on flashing LED datasheets. In another thread someone ran one off rectified 24VAC, so nearly 34V, via a suitable resistor, with no problems.

I wasn´t sure first. This blinking LED also had no datasheet. On the package it says 5V and 20mA and with 5V it works consuming round about 20mA.  :-+ ;D But of course it´s possible that there are a lot of blinking LEDs needing a resistor. I have to admit that was the first blinking LED I had on my table.



Looks nice.

Hey, what's your camera/optics/filters/polarization/lighting?
(I can't find any info on your website, auf Englisch oder Deutsch.)

Thanks!  :)
I have a HowTo-page: https://www.richis-lab.de/Howto.htm
I have to update the pages but basically I still work with this equipment.
Here you can find some discussion regarding the HowTo: https://www.eevblog.com/forum/projects/decapping-and-chip-documentation-howto/msg2663778/#msg2663778


I thought the old style blinking LEDs were fabricated as one chip.

Perhaps I have to take some more pictures...  :)


If you immerse the plastic in an indexing matching liquid such as glycerin (index of refraction 1.47) or corn syrup (index of refraction 1.53), you can make the bulb "disappear."  Then place a flat piece of glass like a watch glass or a microscope slide on top of the liquid and you should get a very good picture.

Thans for the hint!  :-+
 
The following users thanked this post: Zero999, Renate

Offline Noopy

  • Frequent Contributor
  • **
  • Posts: 499
  • Country: de
    • Richis-Lab
Re: Optoelectronics - die pictures
« Reply #7 on: October 08, 2020, 09:17:59 pm »

Let´s look into a infrared camera module: Flir Lepton 2.5








The Lepton 2.5 uses a shutter to calibrate the temperature measured with the microbolometer pixel.




A temperature sensor on top of the module measures the temperature of the shutter (near the shutter  ;)).
Yes, the module suffered some water damage.  ;D




On top of the sensor there are two lenses in a "screw". By screwing this optic in and out you can adjust the focus.
The lenses are probably built out of silicon.




The housing uses a conductive coating. Here you can see the second lens in the "screw".




The sensor module is quite big. Under the die in the middle there is a 0,6mm copper heatspreader. The heatspreader has to guarantee a uniform temperature over the die.
On top of the middle die there is an other die that forms a vacuum chamber. Gases would cool the sensor pixels.




The top level die has a coating to reduce infrared reflection.
The lenses had also a coating.




The top level die has a coating on the bottom to damp light outside the active area.




Some damage...  :'(




Here you can see the sensor array with the first signal processing.
Under the big metal rectangles there are probably the dark reference pixels.
In the upper left corner you can see a small 4x3 array probably also some reference.




One pixel is 17x17µm as Flir states in the datasheet. The diameter of one active area is round about 15µm.




Well it´s kind of a MEMS. You can see the height of the pixels. The distance is important to thermaly isolate the pixel from the substrate.




Even careful cleaning damages the pixel structures.
But here you can see the structures of the last two pixels seem to be corrupted. For a resolution of 80x60 the die uses 84x64 pixels. As seen with the DLP (https://richis-lab.de/DLP.htm) these MEMS-structures need dummy parts at the edge.






Can´t say much about the signal processing flip-chip. Damn underfiller.  >:(




I assume the small one is a voltage regulator.


More pictures here:

https://richis-lab.de/Opto04.htm

 :-/O
 
The following users thanked this post: Dave, kilobyte, doktor pyta, RoGeorge, Miyuki, capt bullshot, sandalcandal

Online capt bullshot

  • Super Contributor
  • ***
  • Posts: 2064
  • Country: de
    • Mostly useless stuff, but nice to have: wunderkis.de
Re: Optoelectronics - die pictures
« Reply #8 on: October 09, 2020, 05:15:16 pm »
Thanks, these are very fascinating pictures.
Safety devices hinder evolution
 

Offline tooki

  • Super Contributor
  • ***
  • Posts: 5559
  • Country: ch
Re: Optoelectronics - die pictures
« Reply #9 on: October 09, 2020, 06:09:51 pm »
Great pictures as always!




In a red cap there is a opaque foil above a white light shaper with a black textured surface.
Well, clearly it’s not opaque — “opaque” means “lichtundurchlässig”. (Same as “opak” in German.) It’d be accurate to call it a translucent film. (“Foil” in English refers exclusively to thin metal, not other materials. Those we call “films”.)
 

Offline RoGeorge

  • Super Contributor
  • ***
  • Posts: 2524
  • Country: ro
Re: Optoelectronics - die pictures
« Reply #10 on: October 09, 2020, 06:25:39 pm »
Wow, that IR sensors!   :o
Very nice pics, thank you.

It looks like there is a small lens above each pixel, and some of the pixels lost their lens.  How are those lens made?  Are they grown on top of the circuit, or fabricated separately then glued on top later?   :-//

Offline Noopy

  • Frequent Contributor
  • **
  • Posts: 499
  • Country: de
    • Richis-Lab
Re: Optoelectronics - die pictures
« Reply #11 on: October 09, 2020, 06:34:05 pm »
Thank you all!  :)

tooki you are right. I was wrong. "opaque" and "opak" are both wrong.
Also the hint regarding "foil" is interesting. Kind of a false friend.
Thank you! :-+


It looks like there is a small lens above each pixel, and some of the pixels lost their lens.  How are those lens made?  Are they grown on top of the circuit, or fabricated separately then glued on top later?   :-//

That small parts are small plates which are mounted elevated over the substrate so they don´t loose thermal energy. You want to isolate these plates as good as possible to convert every infrared photon into a delta T.
At first most of the pixels looked good but while cleaning the die I damaged a lot of them.
The structures are fabricated like every MEMS. You stack special layers and etch one of the lower layers away.
I have written some words about that here: https://www.eevblog.com/forum/projects/dlp-die-pictures/msg2967068/#msg2967068
 
The following users thanked this post: brabus, RoGeorge

Offline tooki

  • Super Contributor
  • ***
  • Posts: 5559
  • Country: ch
Re: Optoelectronics - die pictures
« Reply #12 on: October 09, 2020, 07:45:56 pm »
Thank you all!  :)

tooki you are right. I was wrong. "opaque" and "opak" are both wrong.
Also the hint regarding "foil" is interesting. Kind of a false friend.
Thank you! :-+
Indeed! There are lots of false friends, from the classic “actual” vs. “aktuell”, “when” vs “wenn”, “eventually” vs. “eventuell”, to really subtle ones like the difference between the English word “manager” and the German word “Manager”* (which was obviously borrowed from English, but actually means something subtly different, but similar enough that people who aren’t truly bilingual won’t realize the other person means something else), and amusing ones like “body bag”, which means radically different things** in the two languages! 😂

*English “manager” means a person at any level of management, even way down at the bottom with just one layer of subordinates. In German, “Manager” specifically and exclusively refers to executive-level management. (English “manager” is “Leiter” in German, e.g. store manager is “Filialleiter”.)

**In German, a “body bag” is a one-strap backpack. In English, it’s the bag you use to hold a cadaver.
 
The following users thanked this post: james_s

Offline edavid

  • Super Contributor
  • ***
  • Posts: 3012
  • Country: us
Re: Optoelectronics - die pictures
« Reply #13 on: October 09, 2020, 08:29:58 pm »
(“Foil” in English refers exclusively to thin metal, not other materials. Those we call “films”.)

Except that an overhead projector transparency is often called a "viewfoil"  :-//
 

Offline T3sl4co1l

  • Super Contributor
  • ***
  • Posts: 15895
  • Country: us
  • Expert, Analog Electronics, PCB Layout, EMC
    • Seven Transistor Labs
Re: Optoelectronics - die pictures
« Reply #14 on: October 09, 2020, 09:38:50 pm »
And every so often you see plastics referred to as foils, seems to sometimes show up with polyimide (particularly strong? shiny? golden?), maybe thicker pieces of mylar etc.  Not sure why.

Tim
Seven Transistor Labs, LLC
Electronic design, from concept to prototype.
Bringing a project to life?  Send me a message!
 

Offline tooki

  • Super Contributor
  • ***
  • Posts: 5559
  • Country: ch
Re: Optoelectronics - die pictures
« Reply #15 on: October 12, 2020, 01:33:16 pm »
(“Foil” in English refers exclusively to thin metal, not other materials. Those we call “films”.)

Except that an overhead projector transparency is often called a "viewfoil"  :-//
I never, ever heard them called that when I was in school.
 

Offline tooki

  • Super Contributor
  • ***
  • Posts: 5559
  • Country: ch
Re: Optoelectronics - die pictures
« Reply #16 on: October 12, 2020, 01:34:44 pm »
And every so often you see plastics referred to as foils, seems to sometimes show up with polyimide (particularly strong? shiny? golden?), maybe thicker pieces of mylar etc.  Not sure why.

Tim
Maybe association with the metalized versions of those plastic films.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf