Monthly Archives: September 2010

Most commercial and consumer products are tested and verified in non-condensing humidity environments, which verifies the ability to withstand operating in ambient atmosphere with a high moisture content.

Military and Aerospace products however, are often required to operate in a climatic testing environment where moisture will condense in liquid form directly on the product. This is NOT a test you want to immediately run with out doing some pre-test work.

For one thing, a product has to be designed to withstand this very severe environment. (How to do this could be the subject of another post.) If you “think” your design is good, now go on to some “pre-checks”.

Start by examining all of your conformal coated electronics, in detail under a UV light. Look for small voids. If you have them, you need to revisit your coating process. You would have failed your humidity reliability test.

Next, go the garden supply store and buy a plant mister.

Plant Mister

This device will put out a very fine mist, and when applied to a surface, it will produce a similar effect to condensing humidity. Use plastic sheets and tape to mask off parts of your system, and apply the mist to each circuit board individually, while operating. This will help find vulnerabilities with out having to actually use a humidity chamber, and you will know immediately which sub-assembly needs to be changed to get through this test.

Good Luck.

There’s an old saying “If the only tool you have is a hammer, then all of your problems start to look like nails.”

In the old days of shock testing (writer spits into spittoon) all we had was drop table test machines. 1/2 sine shock pulses were easy to perform (just use rubber under the table), they looked good in the report (when you filtered the heck out of them), and they were absolutely repeatable.

If there is anything an engineer likes better then accuracy in Half Sine Shock Pulse Testing, it’s repeatability.

But what is our excuse today? If we are really interested in finding out how our designs will stand up to real world shocks, why would we use a shock pulse for our testing which never appears in the real world?

Passing a 1/2 sine shock test will NOT indicate that your product will survive the shocks encountered in use and in transportation, nor does failing the test tell you very much useful either, yet these tests are still performed routinely around the world.

It looks like another case of “We’ve always done it this way.”

We live in the era of “Test Tailoring”. It is NOT a big issue to instrument a package, and (gasp)¬†take ¬†measurements! Use those measurements to determine a realistic reliability test requirement. Then you are performing useful testing.

Are you involved in development and release of new products?

Do you need to stay current with the latest product development practices?

Could you use an edge to get back into the job market?

If so The Product Realization Certificate Program can help. An overview of the content and schedule can be found at the link below. or go to the Product Realization Group website and view the EVENTS section for this and other opportunities.