Stereo Microscopes

[Russ]

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.

Thanks for all the help
Russ

 

[mike]

Russ wrote:

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.

Thanks for all the help
Russ

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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[James T. White]

"Russ" <StateStreetAmusements@hotmail.com> wrote in message
newsx5Wd.77849$wc.18932@trnddc07...

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.

Thanks for all the help
Russ


Russ,

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):
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=48740&item=3877925366&rd=1

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.

--
James T. White

 

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.

Thanks
Russ