Measuring SMT device temps with Infrared thermometers

Anyone have any experience with using handheld Infrared thermometers to measure small SMT devices? I see some devices for $30 and up.

It is possible to adjust for the emissivity differences between different materials?

What about the ability to focus on a specific device? Like a SOT23?

We have a very expensive infrared camera which is often used to determine temperatures across an entire circuit board. This is ideal but inconvenient.

Thanks,

A SOT23 is going to be tough, with the IR units I've seen. The spot size is a function of how far unit is away. You'd have to be pretty damn close to be sure you're only picking up the SOT23.

The more expensive ones have a setting for emissivity, or you can just calculate what the true reading is (if you know the emissivity of the part under test). Or, you can just paint it black (for emissivity=1).

Bob

On 27 Mar 2006 00:10:49 GMT, EE snipped-for-privacy@here-dot-com.no-spam.invalid (EE_user) Gave us:

The close focus instruments needed for accurate measurement in this realm are NOT the cheap ones. Especially if you really want accurate, repeatable lab analysis of your circuits.

The emissivity of almost ALL IC chip plastic packages, ie very near .98. This is by design.

A SOT-23 by contrast usually has a lower emissivity as is has a very high polish surface quality. Also for that size device you would most certainly need a specific close focus IR thermometer called a spot thermometer.

Yes, but most of them allow you to used the cursor to analyse specific points within any given captured image.

If you want the best non-imaging instruments in the industry, and you already spent the money for the IR camera, a spot thermometer shouldn't be outside your budget. Look at these from the master's site:

Or the cheaper version:

They also sell a black body calibration source that is NIST traceable so that you can calibrate both your camera, as well as the spot handheld that you may buy.

Trust me, they are better than Raytheon or any of the others.

On Mon, 27 Mar 2006 01:10:21 GMT, "Bob" Gave us:

Some have close focus capacity, but not the ones in Mouser or at Fry's

True.

Not true at all. First off it would have to be a matte black, not glossy, and it will only attain about a .98 emissivity, at best. Then, there are the conductivity issues which may be a problem when "painting" a SOT23 package. Most matte black paints have a carbon based pigmentation.

These guys are the best.

Those look nice. Any idea of the price range?

John

On Mon, 27 Mar 2006 08:03:40 -0800, John Larkin Gave us:

The M-90s are likely a couple grand each.

The MI-N15s are likely half that or less.

The thermal imaging products are much higher.

I don't know exactly. I think they either have a price schedule on the site, or will send you one, however.

OK, I'll check them out. We usually use a tiny thermocouple (or a fingertip!) to measure spot temps. It's an imager that I really lust for.

John

On Mon, 27 Mar 2006 08:47:39 -0800, John Larkin Gave us:

be

Look through their site a bit. These are the guys that have supported the electrical power distribution industry for decades.

Have them send you the free DVDs they offer. They really are enlightening :-] One of them is power industry specific. The other is likely process control specific. Like refractory ovens and such other very high temp items. They even have a couple instruments pointed at the shuttle launch pads from 1000' away (or did)(now it's likely an imager). My how time flies.

They had a 4 inch diameter, 26 inch tube, gold mirrored, rifle scoped and stocked device that most old foggies would remember as the device they used to examine tower insulators or pole mounted transformers, keeping them from having to actually climb up to be near them. If an insulator leaks, as you know, it gets hot.

Now, it appears that all their mirror based tube type reflector instruments have been replaced with those you currently see on their site.

K. Irani, the owner, and president (at least he was) IS the inventor of the resistor bolometer that started this industry back in ... oh...

Since then, there have been many advances in the industry, as you know. Their first imager was only 4 frames per second, had a 386 for processing the image, and was even before they had the capacity to put it onto a VHS tape. Now, as you can imagine, things are much higher res, much higher speed, and can be captured in so many ways, it'll make your head spin.

Other companies which are much larger have even bought their gear in the early days, and made their own versions (Square D, Raytheon, etc.), but nothing beats the traceability of these guys' engineering. They also make the black body sources used by folks like FLIR, etc. where the entire face of the calibration source has to be as uniform in temperature as possible, which as you know, is not an easy feat. Everything is NIST traceable. They even sell a standard NIST calibrated thermocouple for like $800.

I think they may have partners now as the product line looks much more advanced than it was back in the mid '80s (FLIR perhaps).

Your desire to have an imager may be cut down by the price of such gear however. Those babies aren't cheap at all, and they all have to be bought through sales offices now, instead of directly as was the case years ago. That means that a chunk of the price is some lucky, overpaid sales guy's commission. If you can't tell, I have more than a slight disdain for salesmen.

On Mon, 27 Mar 2006 09:25:13 GMT, Roy L. Fuchs Gave us:

Also, painting it will change the way it operates, and alter the data from what it would be in real world circumstances. It would be better to know the actual emissivity of it.