Introduction

The name of DIM-110 came from the Digital Inspection Microscope and the 110 is the work size of the X-Y axes so it is 110mm.

I was into microscope for years now and always wanted a good microscope, but due to the high price and lack of functionality of the microscopes on the used market, I have decided to make one for myself.

I do not want to expain every part of this journey, so if you interrested highly recommend to check out my previous project:

1# Optical scanning microscope

https://hackaday.io/project/166935-optical-scanning-microscope

2# 3D Printed Reflective Microscope

https://hackaday.io/project/176652-3d-printed-reflective-microscope

3# Mobile display reverse engineering

https://hackaday.io/project/179493-mobile-display-reverse-engineering

Before I scare everyone of with this long writing, please watch the short video I made about the machine basic functionality:

Story

I mentioned I wanted a good microscope for myself, but after a lot of try and error I came to a conclusion without good optical components will never have any good result, so I built the reflective microscope. After that I was using it with manual Z axes (with only a screw) and an old plotter base, converted to X-Y stage. I have realised without a good base I will never able to use the microscope for any usefull thing. You quest it I designed one and built the machine base.

This is how you can start with a couple day / week long project and end up with 1-2 year saga.

I do not have to mention, without a good software this machine not capable of any result...

Design

I have used Bosch compatible 2020 and 2040 aluminium profiles for the frame, the reason because easy to work with them and at the end those with the right design can give rigidity. Rigidity is very important factor when we talk about microns, very small amount of vibration or deformation can cause the microscope to become unusable.

It is a bit ridiculous to talk about rigidity when I used 3D printing for almost everything expect the frame. I have used PLA which is fine, PETG or ABS could be a better choice, but I had experience with PLA so I choosed it. I still think with right design it shoud not matter to much.

My main point about the axis setup was, I do not wanted to have a moving gantry. Also not wanted to mount the Z axes on top of the Y axes like usually moving gantry machine has. The reason is simly the further the microscope hang from the frame the higher the deformation and the vibration sensitivity.

The ideal type axis setup is Y axis is on top of the X axis and the microscope mounted only to the Z axes. This may not be the best option for every circumstance, but inmy case when the sample which I want to inspect is a few tens of grams maximum that will not cause deformation for sure. One down side for this setup is the frame have to be bigger than a gantry setup machine.

I have designed the axis only once and made it compatible to assambly an identical one perpendicular to it on top. The axis have a PLA base frame with 30% infill and two 12mm linear rod press fitted into it, this made the PLA frame quite rigid. For the motors I use some used 0.9 degree stepper motors with 8mm threaded trapezoidal rods (sadly I could not find local 2mm trepezoidal rods).

The carriage also printed in PLA and press fitted the 12mm long linear bearings. Made place for the anti-backlash nuts which are cheap chineese one, it is hard to call them anti-backlash when it manufactured so cheap it has +-100micron backlash...

The Z axis design is the same just shortened.

On the below two image you can see the X-Y axis and the whole machine rough design render:

The stage is also 3D printed, I have made it levelable with simmilar solution as 3D printers use for bed. There are 4 screws with springs ont he for corner of the stage and from up it can be leveled with allen key.

Building

I have...

3D scanning with the microscope
Máté Tóth • 08/01/2022 at 19:41 • 0 comments
In the last couple of mounths I had some time to spend on the software side of the microscope and was able to achive very cool thing with it.

The first thing is I made an automated focusing method for it, which uses focus contrast search. It is very simly just stepping in Z till it finds the peak value of the sharpest contrast, like the below picture shows:

On the left bottom two additional parameter needed to be able to start the focus. First is how many steps we want and the second is how big shoud be each step. (for example: 20 step, 0.005 millimeter step size)

Recently I had the idea to use this focus contrast search for 3D scanning the surface of the integrated circuit (die). The idea is the same like what I used in focus method. Starts from the bottom, take a picture and with OpenCV laplacian function search the points which are in focus on the picture. You can see on the GIF I attached below, like how people eyes can see the parts which in focus on a picture, OpenCV can see the same and save these coordinates copied to an array. The Z axes steps 1 or 5 micron up every picture and the code saves the focused parts from each picture.

After it store into an array like a 3D array we can show it with some kind off 3D scatter diagramm, like you see below (the picture and the 3D model is mirrored, still have to fix it):

On the above model we can see a 3D height map from the DIE. The big thing is a broken bonding wire which left over when I openned the IC case. (the hight of that yelow bounding wire peace is 60 micrometer!)

The below GIF we can see a still attached wire bounded connection which goes out to the case of the Integrated circuit.

The map of the attached bonding wire. The wire connect to the square pad. There is quite a bit of noise in the map, but the shape and location can be seen on it:

Next one is a broken Wafer die, which I broke during decapping, but thanks to this one peace on the edge bended up and made a perfect candidate for a 3D scan demo:

The map:

I am quite happy with the results, I have never seen anybody do this before.

Status of the microscope:
- UI interface comming together still have to make it not run serial. Make treading or task managment.
- Can auto focus on any point of the chuck
- Can scan like a snake and from thise pictures stich large maps together
- Rough 3D scan methode implemented, still have to put togehter with DIM-110 software.
- Can scan wavelenght and from that calculate reflectance on sample.
Scanner function
Máté Tóth • 04/07/2022 at 19:28 • 0 comments

I have finnished a function, what this DIM-110 machine can do. It is scanning small objects like IC die's. The actual field of view of the microscope is around 300 micro meter the scanning works like a mosaic, it takes small pictures in a dfined patter and after the 100 or even 1000 of photos stiched together for a big high resolution image.

The machine has image focusing which defines the focus position based on how clear or blury the image is. Before every image the machine focuses the image and then saves the image to a folder, then moves a bit and do the same till it reaches the setted distance in X and Y.

You can see some example of my latest scans of IC die's.

1. LM339 Quad Differential Comparator IC (Original Image size: 6884x6498 pixel or ~44Mpixel)

2. Optocoupler IC die image, probably receiver part (Original image size: 6576x5091pixel or ~33Mpixel)

3. UNL2803 Darlington Transistor Arrays IC (Original image size: 13710x5357pixel or ~73Mpixel)

4. Texas Instruments IC (Original image size: 29861x29784pixel or ~889Mpixel) Image top was not scanned because of faulty setuo of the parameters. This big image was stiched from 1750 smaller image.

Just for comparison there is a video how detailed is a 889Mpixel image (this was intended to be a GIF, there is why the resolution is so small, sorry):

More function and scan will come later!