Author Topic: Decapping and Chip-Documentation - Howto  (Read 46689 times)

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Offline NoopyTopic starter

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Re: Decapping and Chip-Documentation - Howto
« Reply #75 on: July 13, 2021, 10:30:50 am »
I'm pretty sure they have to melt that glass in the factory during production, so hopefully it has reasonably low melting point.

Sounds reasonable. Never thought about that.  :-+


LOL, I may even test if it works because bond wires still appear intact. It is one of my objectives to preserve the pins and wires so I don't have to guess what was connected to where.

 :-+

Offline RoGeorge

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Re: Decapping and Chip-Documentation - Howto
« Reply #76 on: July 13, 2021, 10:32:53 am »
I've read ceramic cases when hit with a hammer sideways, or squeezed in a vice's jaws from sideways, sometimes split top-bottom relative to the die's plane. 

Recently I've read about a very similar technique to remove the metal cover from the top of i7 4790K processors cases (so to stick the radiator right on top if the main dies of the i7, for better cooling, overclocking, etc - i7 4790K was the model with an unlocked multiplier for the core frequency, so very overclock friendly).

Seems like the common idea is to apply sideways pressure and to let the up and down plates to fracture along a plane with maximum defects in the ceramic or other covering material, that plane being the one with the die(s).

Something similar with this https://youtu.be/Fo1KzqCQurk , but seen it with ceramic cases and smaller chips.  Can not find that link with ceramic case split now.  Never tried that myself, so no idea how often chipping ceramic packages with sideways pressure will damage the silicon die.
« Last Edit: July 13, 2021, 10:35:20 am by RoGeorge »
 

Offline NoopyTopic starter

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Re: Decapping and Chip-Documentation - Howto
« Reply #77 on: July 13, 2021, 12:53:58 pm »
I work with hammer and screwdriver to split ceramic packages. That works quite fine for me.

Removing the lid of i7 CPUs always look a little crazy.  :scared:

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Re: Decapping and Chip-Documentation - Howto
« Reply #78 on: July 13, 2021, 04:09:15 pm »
It works, but pins go randomly with either half of the package. And there is some risk that something will go wrong and the whole package will break, taking the die with it.

Anyway, my die looks quite happy so far, no signs of thermal damage. Not sure if it's LF356 or LF357, it's one of those $1 AD797 from AliExpress.

By the way, if anyone ever wondered if those screw-on macro lenses are any good, this photo was taken with a 120mm equivalent lens with the following stack on it:
- B+W 52mm +4D macro filter
- Raynox DCR-250 +8D fancy Japanese achromatic macro filter
- RISE(UK) brand (China) 37mm +10D macro filter
It could be worse :wtf:
« Last Edit: July 13, 2021, 04:13:00 pm by magic »
 
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Offline mazurov

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Re: Decapping and Chip-Documentation - Howto
« Reply #79 on: July 13, 2021, 05:37:54 pm »
Here is another recipe, designed to strip epoxy paints:

https://patents.google.com/patent/CN101649068B/en
With sufficient thrust, pigs fly just fine - RFC1925
 

Offline NoopyTopic starter

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Re: Decapping and Chip-Documentation - Howto
« Reply #80 on: July 13, 2021, 06:58:18 pm »
By the way, if anyone ever wondered if those screw-on macro lenses are any good, this photo was taken with a 120mm equivalent lens with the following stack on it:
- B+W 52mm +4D macro filter
- Raynox DCR-250 +8D fancy Japanese achromatic macro filter
- RISE(UK) brand (China) 37mm +10D macro filter

By the way:
I have done quite some tests with the Canon MP-E 65mm 1-5x.
In the range 1-5x it makes really nice pictures and is a good addition between my Canon 100mm L Macro and my "extreme DSLR magnification setup".
But while getting more magnification (2x extender, bellow rings) the pictures quality is getting worse fast. So in the end I will stay with my 10-22mm construction.


Here is another recipe, designed to strip epoxy paints:

https://patents.google.com/patent/CN101649068B/en

"dichloromethane, formic acid, phenol and sulfuric acid"
I don´t like that...  :scared: ;)

Offline mazurov

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Re: Decapping and Chip-Documentation - Howto
« Reply #81 on: July 13, 2021, 07:35:23 pm »
"dichloromethane, formic acid, phenol and sulfuric acid"
I don´t like that...  :scared: ;)

Still, much easier than nitric. DCM is kind of annoying to work with since it evaporates so quickly,  other ingredients are manageable.
With sufficient thrust, pigs fly just fine - RFC1925
 

Offline NoopyTopic starter

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Re: Decapping and Chip-Documentation - Howto
« Reply #82 on: July 13, 2021, 07:44:09 pm »
"dichloromethane, formic acid, phenol and sulfuric acid"
I don´t like that...  :scared: ;)

Still, much easier than nitric. DCM is kind of annoying to work with since it evaporates so quickly,  other ingredients are manageable.

DCM sounds more than annoying (for me).  :scared:
I always was interested in chemistry but I still have great respect for unhealthy substances.

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Re: Decapping and Chip-Documentation - Howto
« Reply #83 on: July 13, 2021, 09:14:31 pm »
This topic has been beaten to death :horse:

There is no such thing as "the" epoxy resin. It can be any polymer formed by reaction of epoxide groups on some monomer with any other stuff, and there is lots of such polymers with different properties.

Various substances like formic acid or even acetic acid (vinegar), DCM, DMF, DMSO, phenol are known to attack certain epoxies, sometimes at room temperature, sometimes hot. At the same time, they do nothing to ICs.

Myself, I'm tired of that stuff. If it hasn't been tested on ICs, I don't care :=\

As for acids, nitric is way better than sulphuric. Less temperature, cleaner byproducts. But the fumes... And you need to be a terrorist to obtain it in some jurisdictions, or at least a commercial business.
 

Offline RoGeorge

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Re: Decapping and Chip-Documentation - Howto
« Reply #84 on: July 14, 2021, 04:50:49 am »
By the way:
I have done quite some tests with the Canon MP-E 65mm 1-5x.
...

I'm curious if you ever tried cameras with smaller sensor.  Usually DSLR's have big sensors, the more expensive are even full frame, as wide as the old 35 mm film.  This is a disadvantage for macro photography.  Bigger sensors implies less DoF (Depth of Field), this comes from the laws of optics.

The end results for closeups or macro shots are visibly better with a consumer camera (small sensor) than with a DSLR (wider sensor).  For example, when it's to take a PCB shot, my old Minolta DiMAGE Z1 (consumer camera, small sensor) makes nicer shots that looks better than the same shot taken with a Nikon D90 DSLR, because the smaller sensor has more DoF .

You said you use focus stacking to increase DoF, but have you ever tried focus stacking on photos made with a much smaller sensor, like a consumer camera, action camera or even a webcam?  I know for single shots there is a visible difference, but I'm curious if the difference in sensor size will still matter after applying focus stacking.
« Last Edit: July 14, 2021, 04:53:50 am by RoGeorge »
 

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Re: Decapping and Chip-Documentation - Howto
« Reply #85 on: July 14, 2021, 06:52:44 am »
The oracle says: stop down to f/22 :P

I have done quite some tests with the Canon MP-E 65mm 1-5x.
In the range 1-5x it makes really nice pictures and is a good addition between my Canon 100mm L Macro and my "extreme DSLR magnification setup".
But while getting more magnification (2x extender, bellow rings) the pictures quality is getting worse fast. So in the end I will stay with my 10-22mm construction.
That one looks like a lens exactly for the kind of shots that I bodged yesterday.

If you get a chance, you could try the +5D Raynox DCR-150 in your reversed lens setup (screw it onto the reversed lens). It reduces the front side focus distance of a lens to less than 20cm while the lens "feels" like it is focused much further away, this could eliminate some of the problem with reversed lenses not working well at low enough magnification to be useful. DCR-250 is the same but for 125mm, probably too short.

The simple, single-element diopter filters are probably not worth the hassle if you are after high quality. They will create chromatic aberration around highlights, and possibly worse.

BTW, don't be lazy and use those snap-on adapters. They are plastic, and I have seen people selling used Raynox macros with broken adapters, which means that they can break, fall off and make all sort of mayhem. I bought a proper 43mm filter step down ring for mine.
« Last Edit: July 14, 2021, 06:57:49 am by magic »
 

Offline NoopyTopic starter

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Re: Decapping and Chip-Documentation - Howto
« Reply #86 on: July 14, 2021, 07:16:22 am »
I'm curious if you ever tried cameras with smaller sensor.  Usually DSLR's have big sensors, the more expensive are even full frame, as wide as the old 35 mm film.  This is a disadvantage for macro photography.  Bigger sensors implies less DoF (Depth of Field), this comes from the laws of optics.

The end results for closeups or macro shots are visibly better with a consumer camera (small sensor) than with a DSLR (wider sensor).  For example, when it's to take a PCB shot, my old Minolta DiMAGE Z1 (consumer camera, small sensor) makes nicer shots that looks better than the same shot taken with a Nikon D90 DSLR, because the smaller sensor has more DoF .

You said you use focus stacking to increase DoF, but have you ever tried focus stacking on photos made with a much smaller sensor, like a consumer camera, action camera or even a webcam?  I know for single shots there is a visible difference, but I'm curious if the difference in sensor size will still matter after applying focus stacking.

That´s a very complex topic.
Up to now i haven´t tried smaller sensors because:
- I would have to built a robust mount for the combo (no easy task).
- The DoF is no bigger problem for me. For tilted pictures with my magnification I will always need focus stacking. Without tilting a die is flat enough to get everything in focus.
- The limit for the magnification is the lens, not the sensor. In theory my setup gives me 200nm / pixel but effectively the resolution is between 1 and 5µm.

One interesting point here: Reducing the aperture ("f/22") reduces the magnification! You need a 2.0 lens to get a lot of resolution in this case.
(I have tested a 35mm 2.0 but the image quality was worse...  :()


If you get a chance, you could try the +5D Raynox DCR-150 in your reversed lens setup (screw it onto the reversed lens). It reduces the front side focus distance of a lens to less than 20cm while the lens "feels" like it is focused much further away, this could eliminate some of the problem with reversed lenses not working well at low enough magnification to be useful. DCR-250 is the same but for 125mm, probably too short.

Well it´s worth a try...  :-+


Edit: There was a guy who calculated the resolution of my system (10mm, f/3.5). He came up with 1-2µm which fits quite well to my pictures.
« Last Edit: July 14, 2021, 07:23:02 am by Noopy »
 

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Re: Decapping and Chip-Documentation - Howto
« Reply #87 on: July 14, 2021, 07:52:57 am »
Rules of thumb in microscopy:

F-number to numerical aperture:
NA = 0.5 / F

Numerical aperture to resolution (Abbe criterion):
d = 0.3µ / NA (for 600nm light, or λ/2/NA in general)

The resulting d is the minimum distance between two identical points (or lines) that are "barely resolved", or smeared onto each other with a small dip in intensity between them.

For f/3.5, NA is 0.14 and d is ~2µ.

AFAIK those approximations are valid when one side of the lens is focused at infinity, which means that resolution can be slightly (up to twice?) worse at close to 1:1 magnification. That's not a big deal for most of the time.
« Last Edit: July 26, 2021, 11:01:31 pm by magic »
 
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Re: Decapping and Chip-Documentation - Howto
« Reply #88 on: July 20, 2021, 02:30:38 pm »
Of course, the above rules can be conveniently combined to:
d = λ · F

And I suppose F/2 could also work if you are seriously lazy.

My LF357 (compensation caps are much smaller than on Noopy's so I figure it must be the 7) really looks quite fine despite the temperature. But I still haven't checked if it works because I try to keep it dust free for testing of my new microscopic system.

Project objectives:
- capability to inspect ICs still partly in the package (CERDIP, TO220 - these are very hard to remove completely)
- better structural rigidity than offered by a matchbox :P
- better image quality if possible, please

Long story short, I bought a lot of M42 macro extension tubes and some thread adapters. Then with that stuff and some plastic sheets and paperboard I constructed an M42 epi-illuminator (45° half-mirror plus a hole in the wall) and - possibly the first in the world - M42 mount webcam ;D

I experimented with various setups and this is the winner so far: 10x biological microscope objective (abused at infinity focus, seems not to mind it much), the illuminator, Raynox DCR-250 macro, 125mm of M42 tube, the webcam. The whole tower is supported vertically above the IC by another stack of M42 tubes, partly unscrewed so they work as focus adjustment.

Remaining problems:
- some chromatic aberration - likely from the objective (it's old junk and I have dropped it on a hard surface once, so maybe that's why)
- still imperfect illumination, you can see some areas are brighter and/or different shade than others

Not problems:
- detail and resolution - nice and clean
- contrast and color - it's just this damn LF357 looking dull, I may upload some sexier dice later to show what the system is capable of

The LF357 picture below is a mosaic of 7×5 images captured with the webcam, stitched in hugin, postprocessed and scaled 50%. IMHO it's not too bad, and the setup is pretty low cost (the Raynox being the worst offender), mostly DIY and highly tweakable.
 
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Offline NoopyTopic starter

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Re: Decapping and Chip-Documentation - Howto
« Reply #89 on: July 20, 2021, 07:15:03 pm »
Interesting!  :-+
Pictures please! (of the optical stack)

What kind of 45° half-mirror do you use?

How much distance is between the microscope objective and the die?

In my view the illumination is not bad! Hey that´s no Zeiss-20k€-darling!  ;)

I would recommend some tonal correction / saturation:





Do you like Hugin? I tried it once and had some problems.  :-// Helicon Focus is more foolproof but unfortunatelly sometimes does crazy things.  ???

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Re: Decapping and Chip-Documentation - Howto
« Reply #90 on: July 21, 2021, 03:38:14 pm »
First goes the stack of M42 tubes with the M42-RMS adapter and the objective on top.
Onto that goes the illuminator. It's a simple construction using black paperboard and the good old smartphone mirror foil. It's not really a foil, it's a pretty stiff plastic sheet and it maintains shape well. Light enters through a 6mm hole in the wall (on the left) and there is no more hidden tricks in there.
Next is the Raynox with necessary thread adapters and ~125mm of M42 tubing.
The camera is bolted to a plastic disc and screwed onto the top of the tower with a short M42 tube.

Also shown, a webcam lens converted to fit the M42/RMS setup using another disc and some hot glue ;)

How much distance is between the microscope objective and the die?
Common achromatic 10x 0.2NA objectives tend to have ~1cm working distance.
With 20x 0.4NA it drops dramatically to 1~2mm.
More NA tends to be <1mm and reportedly performs poorly without a cover glass (biological objectives compensate for it).
It should be listed on the spec sheet.

I would recommend some tonal correction / saturation
Sure you can send contrast and saturation into the stratosphere, but it also amplifies faults. If you go too hard on that LF357 picture, the brighter-reddish and darker-greenish vertical bands become more visible.

Do you like Hugin? I tried it once and had some problems.  :-// Helicon Focus is more foolproof but unfortunatelly sometimes does crazy things.  ???
Well, it's the first thing I tried and it worked out with a bit of tweaking.

It slows down a lot with many images (several minutes to align the 35 parts of LF357) because it tries to match every one with each other. I don't know how to tell it what the correct layout is. Somewhere on Zeptobars there is a "behind the scenes" post with an example of terribly screwed up Hugin job because it found similar features on images which just aren't adjacent to each other and warped everything to join those images anyway.

Hugin detected that each of my images contains that brighter-darker gradient and decided to brighten up the left side of the die and darken the right side so that the gradient is consistent across the whole image. I had to tweak that correction semi-manually - that's why there is a version 2.
 
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Offline NoopyTopic starter

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Re: Decapping and Chip-Documentation - Howto
« Reply #91 on: July 21, 2021, 07:01:10 pm »
Hugin detected that each of my images contains that brighter-darker gradient and decided to brighten up the left side of the die and darken the right side so that the gradient is consistent across the whole image. I had to tweak that correction semi-manually - that's why there is a version 2.

Well with Helicon Focus at least you can place the pictures in the right position.
If Helicon Focus merges the pictures shifted a little you can correct that by moving the unprocessed pictures. But it´s more or less pure luck if the "shifted" picture gets better.  ::)

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Re: Decapping and Chip-Documentation - Howto
« Reply #92 on: July 22, 2021, 06:31:06 am »
The post about Hugin was on Ken Shirriff's blog, not Zeptobars.
http://www.righto.com/2015/12/creating-high-resolution-integrated.html

I measured the LF357 with caliper and it's pretty much bang on 2×1mm. So the scale of my "scan" is 3px/µ before scaling or 1.5px/µ as posted at 50% size.

Calculated field of view is 0.5mm in diameter out of 2mm the lens is supposed to produce (10x magnification and 20mm nominal output). A larger sensor could deliver more FOV (and expose more illumination defects :P).

Anyway, I think I have beaten those popular "USB microscope" toys at least :box:

A much simpler setup is also possible with finity focus, no Raynox and either a scope objective or a webcam lens. But I found it to have somewhat worse contrast. Maybe further work on illumination is needed. It's not perfectly aligned and I still look for suitable light sources. 5mm LED is a bit too small, a larger LED torch is quite uneven, additional optics a'la Kohler is bulky and inconvenient and still not perfect for some reason ::)
« Last Edit: July 22, 2021, 06:36:44 am by magic »
 

Offline NoopyTopic starter

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Re: Decapping and Chip-Documentation - Howto
« Reply #93 on: July 22, 2021, 07:43:00 am »
The post about Hugin was on Ken Shirriff's blog, not Zeptobars.
http://www.righto.com/2015/12/creating-high-resolution-integrated.html

"The next step is to fix the control points. Because Hugin optimizes globally, even a few bad control points can mess up the entire image."
Do you have to put/check control points at every picture pair? For me it looks like I have to do so and that can be quite an effort.

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Re: Decapping and Chip-Documentation - Howto
« Reply #94 on: July 22, 2021, 10:42:56 am »
Honestly, I just loaded my images and ran the "scanned images assistant" from the menu, figuring that this is the closest thing to what I am trying to achieve. This took a long time (maybe 15 minutes) but it got the job done, except for the exposure gradient which I had to override in expert mode.

I now tried again fully in expert mode and without those "assistants".

At first, I ran automatic control point detection because I definitely am too lazy to add points by hand. This took one minute and found spurious control points, joining the upper input JFET with the lower one. I ran geometry optimization to see what happens and it produced the nice layout attached below. It seems that Hugin tries to minimize average mismatch of control points and shrinks the input stage a little to bring the false control points closer together at the cost of slightly misaligning the correct ones.

With a bit of clicking around I found two useful options. Firstly, right clicking on the image list brings up a menu with an option called "manipulate image variables". Here there are choices like "linear panorama with 20% overlap" or "two row panorama with 20% overlap" - neither is ideal, but I "loaded" the linear panorama preset and clicked OK to see what happens. As expected, the images became arranged in a long train, one row after another.

The second useful option is the choice of "Hugin CPFind (prealigned)" in the feature matcher selection. This finds control points as usual, but it only considers pairs of images which are currently overlapping. It took only half minute and found useful control points horizontally and no wrong control points. After a run of geometric optimization my five rows became neatly aligned, but they were still placed in a few random places on the plane. (I don't know why it didn't put them all in the center on top of each other, but I don't complain.)

To combine the rows, I selected pairs of first images from consecutive rows (11+21, 21+31, ...) and ran control point search on each pair. Then another geometric optimization placed the rows in the correct order, but there were still no control points for most vertical and diagonal pairs. So yet another prealigned control point search and another round of optimization. The final result was good and stitched cleanly.

So there is a light in the tunnel :phew:
I think the next obvious step is to figure out how those "manipulate image variables" presets work and how to arrange everything in the correct number of rows from the beginning.

BTW, those PTO files are simple text files so it should also be possible to write a script which sets image coordinates to whatever we want.
 
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Offline NoopyTopic starter

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Re: Decapping and Chip-Documentation - Howto
« Reply #95 on: July 22, 2021, 03:27:13 pm »
Thanks for the explanation!
Perhaps I start another try with Hugin.
Helicon Focus doesn´t work bad enough for a fast changeover.  ;D

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Re: Decapping and Chip-Documentation - Howto
« Reply #96 on: July 22, 2021, 08:03:53 pm »
Well, maybe not so fast. I encountered another problem: wrong CPs on a correct pair of images. For example, different fingers of the same transistor. But they have been rare so far and easy to find by opening the CP list and sorting it by "distance" (see Ken Shirriff).

It may get worse on ICs with a lot of repetitive features.

I solved the problem of pre-aligning multiple rows. For whatever reason, and at least on my system, the "manipulate image variables" window opens with just a few buttons. But if I enlarge it, suddenly a text box appears which hold the script to be executed. Modifying the "two row panorama" script for five rows is a matter of changing one number and then it works for me.
 

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Re: Decapping and Chip-Documentation - Howto
« Reply #97 on: July 24, 2021, 08:11:40 am »
What's the deal with the weird shadows on SDH112? One of those crazy things that Helicon Focus does? ;)

Maybe we should just figure out how to correct brightness gradients with ordinary image editors before running those stitchers...

Well, maybe not so fast. I encountered another problem: wrong CPs on a correct pair of images. For example, different fingers of the same transistor. But they have been rare so far and easy to find by opening the CP list and sorting it by "distance" (see Ken Shirriff).
This has been resolved, at least for LF357. I plan to scan some more difficult IC and see how good it really is.

It turns out that CPFind is not entirely retarded and it doesn't just look for similar points on both images, but it looks for a set of similar points which can be aligned by transforming the images in some way. By default, it considers any homographic transformation, which is quite a lot of different distortions that can occur when shooting a large object from different places at different angles, but they simply don't occur here.

The solution is to change "ransacmode" to "rpy" and set the horizontal field of view absurdly narrow (1° seems OK) so that Hugin's pitch and yaw coordinates (p,y) are more or less equivalent to shifting the camera sideways (x,y). This requires going to preferences and defining a new control point detector. And then choosing to use it, of course.

http://hugin.sourceforge.net/docs/manual/Cpfind.html
http://hugin.sourceforge.net/docs/manual/Hugin_Parameters_for_Control_Point_Detectors_dialog.html
 

Offline NoopyTopic starter

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Re: Decapping and Chip-Documentation - Howto
« Reply #98 on: July 24, 2021, 08:42:53 am »
What's the deal with the weird shadows on SDH112? One of those crazy things that Helicon Focus does? ;)

 ::) ;D

Helicon Focus is innocent this time. Sometimes I have problems with the light. Working with a fixed exposure doesn't always work for me because the light from behind fluctuates at different locations of the die.
Often I can improve the picture quality with a second and a third try but sometimes I consider the quality as "good enough".  :D

Offline NoopyTopic starter

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Re: Decapping and Chip-Documentation - Howto
« Reply #99 on: July 24, 2021, 08:48:54 am »
Maybe we should just figure out how to correct brightness gradients with ordinary image editors before running those stitchers...

That's not always possible. In my pictures often it's not only the brightness but also "the color" that differs.
I will try a "half mirror light solutions" similar to yours. Perhaps that gives more constant light quality.


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