Customer Goal

A customer approached DES looking to perform Highly Accelerated Life Testing (HALT) on a new circuit board design.  DES and the customer agreed to test the circuit boards using DES’s traditional HALT test procedure which calls for hot/cold temperature steps followed by rapid temperature ramping, vibration steps and combined temperature and vibration stresses.  HALT testing on electrical componentry is quite common across industry to expose design weaknesses; both mechanical and electrical (What is HALT and Why Perform HALT?).  Typical failures include poor solder connections, overheating, component failure, etc. (What Kind Of Failures Occur During HALT?)

Results

The hot/cold temperature steps exposed soft failures such as power resets and lack of communication for the circuit boards.  One hard failure was also exposed during this stage which proved to be a recurring problem and thus an area of weakness in the product design.  The units functioned properly during the vibration steps and rapid thermal ramping stages.  The combined temperature and vibration stage, however, revealed the same issue as seen in the first stage on two other units.

The circuit board featured potted componentry for purposes exclusive to the customer.  This potted feature cracked on multiple units throughout testing and caused all sorts of communication issues for the units.  In 3 days the customer was able to expose a product design weakness that would most likely have caused a number of warranty and reliability issues.  In the words of the customer:

“The results from this testing have identified strong and
more importantly weak areas in our design.”

– Customer

HALT testing is a necessity for products with electrical circuity in terms of preventing field failures and high product return rates.  Problems such as these can be really damaging to a company’s bottom line if not addressed early in the design process.  Fortunately this customer has had experience with HALT in the past and chose to perform HALT before finalizing the product design.  DES has over 20 years of experience performing HALT testing on a variety of medical, commercial, industrial and military products.  Schedule your next HALT test with us by contacting us or call us at 610.253.6637.

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A customer approached DES looking to find an accelerated test solution for an AC powered cooling fan used in one of their products.  The product had been established in the marketplace and the company was now looking for ways to reduce cost by looking at different cooling fan suppliers.  Most fans, however, have a mean life rated for over 20,000 hours, so a typical accelerated life test would require a significant amount of time and money. 

DES Solution

Performing a quantitative accelerated life test on cooling fans presents challenges because they have such a long lifespan.  Reasonably speaking, the shortest quantitative solution for determining the lifespan of a fan could take as long as a couple months.  DES proposed a qualitative solution, a Rapid HALT.  A Rapid HALT (Highly Accelerated Life Test) is designed to apply a variety of stresses, concurrently, to a product in order to significantly time compress a product’s lifespan.  A typical Rapid HALT lasts only one day which is extremely convenient for companies that need results quickly.

Results

A sample size of 3 cooling fans were tested for 4 different fan suppliers.  We will refer to these suppliers as Supplier A, B, C and D.  All 12 fans were placed in the chamber together and a Rapid HALT was conducted.  None of the four suppliers survived testing without some issues but the results were still differentiating.  Supplier A had no electrical issues in any of its samples but the fan blades on all 3 samples vibrated off the armature.  Fans of Supplier B, all experienced sputtering of the fan blade and eventually saw two of its fans current levels drop to 0.  By the time testing was completed, none of the fans were functioning.  Supplier C fared slightly better than A and B.  One of Supplier C’s fans lost current at the most extreme step and never recovered.  The other two however, experienced fan blade sputtering but were functioning normally upon final inspection.  Supplier D performed the best out of the four suppliers and thus would be considered the most durable of the suppliers tested.  Only one of the fans experienced any issues, in which it lost current at the most extreme step.  Upon final inspection all of the fans were functioning normally.

There are other factors to consider such as price and accessibility but these results were able to successfully assist our customer in differentiating between the reliability of the four fan suppliers.  While a HALT is qualitative and will not produce an actual estimated fan lifetime, it is a great comparison tool to evaluate the reliability of different suppliers faster and less expensive than traditional testing techniques.

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DES was awarded multiple contracts to perform combined temperature and vibration reliability testing of Mass Air Flow Sensors from various automotive part manufacturers and from a major auto parts supplier.

The applicable test specification was GMW 3172, a General Motors Specification for electronic component durability.  The test requirements in GMW 3172 were 13 Grms random vibration from 10 to 2000 Hz.  Simultaneously with the vibration testing, DES’s AGREE Chamber subjected the MAFS’s to temperature cycles between -40 °C and +125 °C.  In addition to the harsh temperature and vibration environment, the sensors were electrically powered and monitored for operation or failure during the test.  These harsh conditions had to be run for at least 44 continuous hours per axis along three different axes.  Sometimes they were run for longer durations.  Many sensors were tested simultaneously which added to the challenge.  Finally, a bench air flow tester was used to perform calibrated air flow measurements after each axis to verify the electrical output of each sensor.

This case study shows the advanced capabilities of DES to complete the most difficult temperature and vibration test projects.

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