HALT testing

Now *that* is interesting.

Imagine a temperature, vibration, RFI chamber! May as well do altitude, too.

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rature sweeps at temperature extremes of minus 40 and plus 125 degrees were ok. I learned from that, that HALT testing with data logging during sweeps can be informative

f components, but miss that the HALT fan in blowing air in at high rates, s o components only rise little above the HALT chamber temperature setting

interesting, I thought temperature tests were done with a box in a box

i.e. the DUT is in a aluminium chamber that is inside temperature controlle d chamber fans/heaters/coolers etc. only in the outer chamber

-Lasse

Dangerous, too, on a steering wheel, or brake pedal.

On Sunday, March 2, 2014 7:48:42 PM UTC+1, Lasse Langwadt Christensen wrote :

cost?

perature sweeps at temperature extremes of minus 40 and plus 125 degrees we re ok. I learned from that, that HALT testing with data logging during swee ps can be informative

of components, but miss that the HALT fan in blowing air in at high rates, so components only rise little above the HALT chamber temperature setting

led chamber fans/heaters/coolers etc. only in the outer chamber

Normally the DUT is placed inside the HALT chamber with enclosure, so you g et the mechanics in the equation also. But, just ask yourself, what happens if you have a massive 150mm dia tube with controlled temperature high spee d air, pointed at that DUT. The DUT enclosure is cooled to the chamber temp erature setting.

Now, if the enclosure is without holes for air cooling, the enclosure lacks self-heating and presents a better cooling path than in still air

If the enclosure on the other hand has holes, the air from the outside crea tes turbulence and other effects inside the enclosure

In other cases the enclosure is taken off, so you can observe if any compon ents are dammaged during vibration. But then the temperature tests are way off (if you were seeking hotspots)

Cheers

Klaus

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emperature sweeps at temperature extremes of minus 40 and plus 125 degrees were ok. I learned from that, that HALT testing with data logging during sw eeps can be informative

re of components, but miss that the HALT fan in blowing air in at high rate s, so components only rise little above the HALT chamber temperature settin g

olled chamber fans/heaters/coolers etc. only in the outer chamber

get the mechanics in the equation also. But, just ask yourself, what happe ns if you have a massive 150mm dia tube with controlled temperature high sp eed air, pointed at that DUT. The DUT enclosure is cooled to the chamber te mperature setting.

ks self-heating and presents a better cooling path than in still air

eates turbulence and other effects inside the enclosure

onents are dammaged during vibration. But then the temperature tests are wa y off (if you were seeking hotspots)

maybe I wasn't clear, imagine a 4*4*4 meter temperature controlled room, in side that room you put a 3*3*3 meter metal box, inside that room you put yo u DUT

all the heaters/coolers/fans are in the outer most room

-Lasse

Pictures I've seen have a couple of huge hoses blasting air directly onto the DUT. That's probably how they get the extreme dT/dt numbers.

On Sunday, March 2, 2014 8:38:10 PM UTC+1, Lasse Langwadt Christensen wrote :

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it cost?

Temperature sweeps at temperature extremes of minus 40 and plus 125 degree s were ok. I learned from that, that HALT testing with data logging during sweeps can be informative

ture of components, but miss that the HALT fan in blowing air in at high ra tes, so components only rise little above the HALT chamber temperature sett ing

trolled chamber fans/heaters/coolers etc. only in the outer chamber

ou get the mechanics in the equation also. But, just ask yourself, what hap pens if you have a massive 150mm dia tube with controlled temperature high speed air, pointed at that DUT. The DUT enclosure is cooled to the chamber temperature setting.

acks self-heating and presents a better cooling path than in still air

creates turbulence and other effects inside the enclosure

mponents are dammaged during vibration. But then the temperature tests are way off (if you were seeking hotspots)

inside that room you put a 3*3*3 meter metal box, inside that room you put you DUT

Well that isn't HALT testing, like it is done

Search for HALT chambers on google to see how it's done

Cheers

Klaus

...or seats. Its less than useless (likely not good for the plastic, either).

Reminds me of the story about the change from round to rectangular (sealed halogen) head lamps. When the auto makers wanted to make the change, they asked DOT for specs. They basically were told that the pattern had to be identical to the old sealed beams. OH, how many points need to be tested to meet the spec. The government (DOT) came back and said "all of them".

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s. Temperature sweeps at temperature extremes of minus 40 and plus 125 degr ees were ok. I learned from that, that HALT testing with data logging durin g sweeps can be informative

rature of components, but miss that the HALT fan in blowing air in at high rates, so components only rise little above the HALT chamber temperature se tting

box

ontrolled chamber fans/heaters/coolers etc. only in the outer chamber

you get the mechanics in the equation also. But, just ask yourself, what h appens if you have a massive 150mm dia tube with controlled temperature hig h speed air, pointed at that DUT. The DUT enclosure is cooled to the chambe r temperature setting.

lacks self-heating and presents a better cooling path than in still air

e creates turbulence and other effects inside the enclosure

components are dammaged during vibration. But then the temperature tests ar e way off (if you were seeking hotspots)

, inside that room you put a 3*3*3 meter metal box, inside that room you pu t you DUT

I see it, learn something new everyday

-Lasse

Over-stressing,at least for HI-Rel testing is NOT done; it is termed as accelerated life testing; 1000 hours. Do not remember test timepoints.

This is an issue in any environmental chamber. If temperature effects are your interest, using a regular thermal chamber will be easier and more direct. The turbulence in the HALT or HAST chamber isn't easily avoided if rapid temperature variations are to be created.

Various applications methods are used to allow stabilized readings at specific ambient levels within the HALT profile. This can only really be confirmed by the logging record. I'm unaware of any HAST program that doesn't log data.

Note that the vibration accompanying the test also reduces thermal impedance, through turbulent scrubbing.

RL

cost?

Temperature sweeps at temperature extremes of minus 40 and plus 125 degrees were ok. I learned from that, that HALT testing with data logging during sweeps can be informative

temperature of components, but miss that the HALT fan in blowing air in at high rates, so components only rise little above the HALT chamber temperature setting

controlled chamber fans/heaters/coolers etc. only in the outer chamber

Though not common, to get that, all you have to do is specify it in the test regime.

?-)

I love the creep of silicone products. In no time everything is is shiny and uncleanable. Trying to wipe the crap away just leaves an even brighter "polish".

Flipping though a Dow catalog they listed some sort of fast evaporating silicone based silicone solvents that were described to act evaporate somewhere between alcohol and acetone. I can't even imagine how weird that stuff is.

Trying to rub label adhesive off soft plastic is enough for me.

I used perfluorohexane in an experiment once--it really does evaporate like acetone. Its viscosity is roughly like boiling water.

Cheers

Phil Hobbs