Could someone offer me some advise on purchasing a stereo microscope for SMD work. I have tried all of the little hand held things and it isn't working out. Before I make a mistake and buy something that I think is right for the job maybe someone can point out the features to look out for and the best places to buy from. I guess I need it one on a boom stand to check chips on bigger boards. Should I buy a fix mag lens if so do I need 10X,
20X 40X? Is that to much? Should I us a variable. What about lighting. Will a florescent ring be ok or should I use halogen. Anything else to look out for. EBay has some from under $100.00 without the boom and starting at $300.00 with a boom. Any regrets from owners of these things. Any must have's.
As always, depends on what you're trying to do. I bought a Zoom Stereo Microscope just cause it was cheap. I was generally disappointed. It would be ok for inspection, but trying to work under it is a nightmare. Not enough clearance, small depth of field, small width of field, takes two hands to operate it.
If you have a fixed setup that's always in the field and in focus and the tools are designed to work under it, it could be great. For general work, I went back to head mounted magnifiers.
For inspection, I think I'd try a camera and view it on a video monitor. mike
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I use one all the time that we got from amberdepot on eBay to SMT assembly and inspection. The smallest lead spacing we've worked with so far is 0.65mm but
0.5 mm wouldn't much different. It's a trinocular, 7 - 45X variable microscope with optional boom stand, 0.5X front objective lens, florescent ring light and video camera. This and most of the 7 - 45X scopes actually have a body that is
0.7-45X and are equipped with 10X eyepieces. The 0.5X front objective (sometimes called a Barlow lens) reduces the magnification to 3.5 - 22.5X but extends the working distance (distance from bottom lens to object your are viewing) to about 7" which is adequate for PCB work. The microscope is from China but works great. After using the microscope, I wonder how we got things done with only a LUXO magnifier light. I even find myself using it to place
1206 caps and resistors just to reduce the eye strain.
Here is one just like we have (ring light, 0.5x front objective and video camera are extra):
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There are several other sellers on eBay that have binocular/trinocular microscopes that look very similar and have similar specs, so shop around and ask the sellers a lot of questions.
Options and things to consider:
1) The more light you have the better. The florescent ring light works ok, but I often find myself pulling over the Luxo to add more light. I think there are two types of florescent light rings, 8W and 12W. I'm pretty sure ours is the 8W so the 12W one would be better. I think one of the halogen light units with either the ring light or dual spot light pipes, while quite a bit more expensive would be worth the extra cost. I wouldn't go with the non-lightpipe halogen lamps due to their heat generation, particularly if you plan to solder under the scope.
2) While the 0.5x Barlow objective lenses increase the working distance enough, there are times when having an even longer working distance would be nice. Some vendors offer a 0.3x which would extend the working distance to about 12". It would reduce the magnification but you could make up for that by using higher power eyepieces. I've seen eyepieces in 10X, 15X, 20X and 25X.
3) Take a look at the size of the front objective and the eyepiece lenses as part of your evaluation. With optics bigger is generally better since increase your field of view and let more light through.
4) For PCB work, I consider a boom stand to be a must. Our microscope stand has a single-arm boom and can be a bit difficult to position at times. One of the dual-arm boom stands would be an improvement. Also, take a look at the vertical adjustment range at the microscope end of the boom. Being able to raise and lower the microscope head only (not just with the rack and pinion) without having to raise the whole boom is a real plus when you are trying to inspect solder connections and need to look at the side of a component. Having stop rings for the vertical adjustments makes repositioning the scope back to your primary settings much easier after you've moved it up to inspect something so make sure the boom stand you get has those at a minimum.
Hope this helps and let us know how things turn out.
Thanks for all of the very helpfull info. It doesn't look there is going to be a cheap way to go about this. It looks like $400-$800.00. But that is why I needed the advise. I didn't want to buy some cheap Mickey Mouse thing and end up putting it on the shelf and buying the one I should have bought the first time. It was good to hear that the the import scopes work well. Thanks James for the details. What you talk about is exactly what I was worried about. I really appreciate your advise.
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