Most vibration test specifications require vibration testing along 3 orthogonal axes. Vibration testing using most ElectroDynamic (ED) Shakers is performed 1 axis at a time. However the orientation of the ED shaker or the Device Under Test (DUT) can be changed to complete testing along all 3 orthogonal axes.
Many ED shakers can be rotated and connected to a horizontal table called a slip table,
When products are mainly exposed to temperature stresses in the field, Constant Temperature Accelerated Life Testing is used to simulate product life. Products can be tested at temperatures above their normal use temperature during Constant Temperature Accelerated Life Testing in order to accelerate aging. Defects or failure modes that would show up after many years in the field at normal use temperatures can be detected in short times in an Accelerated Life Test. In Constant Temperature Accelerated Life Testing, the typical failure mode is dependent on migration/diffusion or chemical reactions. These types of failures are typically found in electronic components but can also occur in other types of products or materials such as adhesives, batteries, etc. The Arrhenius Equation relates reaction rates to temperature and is used to correlate time in the field at normal use temperature to a Constant Temperature Accelerated Life Test. It should be noted that constant temperature testing will not precipitate failure modes due to thermal cycling. Temperature or thermal cycle testing will be discussed in another blog article.
The Arrhenius Equation that relates reaction rates to temperature is:
Continue reading Constant Temperature Accelerated Life Testing using the Arrhenius Relationship →
First, DES developed a reliability test plan that defined how the tests would be performed, the number of samples required and how the test results would be quantified into a field life. After the plan was approved by the manufacturer, the reliability test had to be designed.
Continue reading Product Life Cycle Testing of a Drawer Used in a Medical Product →
Classical shock testing consists of the following shock impulses: half sine, haversine, sawtooth, and trapezoid. Pyroshock and ballistic shock tests are specialized and are not considered classical shocks. Classical shocks can be performed on Electro Dynamic (ED) Shakers, Free Fall Drop Tower or Pneumatic Shock Machines. The parameters required to define a shock test are peak acceleration expressed in G’s or m/sec^2, shape of the impulse, and duration in milliseconds. A classical shock impulse is created when the shock table changes direction abruptly. This abrupt change in direction causes a rapid velocity change which creates the shock or acceleration impulse.
Classical shocks are applied along one direction and one axis at a time. Most specifications require the product to be shocked in both the positive and negative directions along each axis. If shock tests are performed on an ED shaker, the shaker can reverse polarity and perform the shock along both directions of each axis without rotating the fixture and specimen. When performing shock testing on a shock machine, the machine can only apply shock in one axis and one direction. The fixture and specimen must be rotated to apply shocks along different directions and axes.
A typical shock test setup using a pneumatic shock machine is shown in Figure 1. DES can also perform shock testing using an ED shaker and drop tower.
We completed a Pyroshock test on our Mechanical Impact Pyroshock Simulator (MIPS) on equipment that will fly into outer space.
On the other end of the altitude spectrum, we completed environmental testing of components that will be used in submarines to MIL-E-917. MIL-E-917 is a military specification for Naval shipboard electric power equipment.
In the middle of the altitude range, we performed combined temperature and vibration testing on sensors that will be used in automobile engines to specification GMW 3172. GMW 3172 is a General Motors Specification for electronic component durability.
The following is a sample of some additional testing projects we have completed recently:
The most common types of vibration testing services conducted by vibration test labs are Sinusoidal and Random. This primer is an explanation of the typical requirements found in vibration test specifications and the parameters used to control the vibration tests. Both types of vibration tests are used to evaluate products for ruggedness, durability and to expose vibration defects.
Product reliability is essential to success in today’s competitive global market. HALT and HASS are intensive methods used to expose and then improve design and process weaknesses. HALT and HASS are faster, less expensive and more accurate than traditional testing techniques. HALT and HASS are proven processes used to lower product development and manufacturing costs, compress time to market, reduce warranty costs, improve customer satisfaction, gain market share and increase profits. Some companies have reported savings in the millions after using HALT and HASS.
HALT and HASS can accelerate a product’s aging process from actual months into test minutes much faster than traditional testing!
Continue reading An Informational Guide to HALT and HASS →
This article discusses the reliability challenges of switching over to lead-free solder and the test methods used to demonstrate reliability, written by Gary Delserro and published in Evaluation Engineering Magazine. Click on the link to download the article in PDF,Lead Free Solder Reliability Issues & Test Methods.
Environmentally friendly is a term rapidly invading the electronics industry.
The electronic industry will be facing great challenges over the next few years as the solder used in electronic products is migrating toward lead-free. This is being driven by mandates in Europe such as Waste Electrical and Electronic Equipment (WEEE) and Restrictions of Hazardous Substances (RoHS) and similar ones in Japan. There also is a great deal of pressure in the US to do the same.
Continue reading Lead Free Solder Reliability Issues and Test Methods →
This article discusses an abbreviated technique that uses the tools of HALT to expose hard-to-find defects in products returned by customers, written by Gary Delserro and published in Evaluation Engineering Magazine. Click on the link to view the article in PDF, Exposing Hard to Find Defects.
How many times have your customers returned products or circuit boards with reported defects that you can’t find? Every manufacturer experiences this situation at some time. Your customer reports a problem in your product and sends it back to you. You test the faulty product in your lab and the problem doesn’t occur. Sometimes you try to bend it or tap it against the table. You may even try heating it in a chamber or with a heat gun or using a freeze spray. Still the problem does not expose itself.
Welcome to DES’s new Website and Blog! This blog will feature news and technical discussions about reliability testing, environmental testing and DES’s services. We look forward to you visiting our Website and participating in the Blog. As the blog develops interest, we hope to have good discussions about our testing services. Feel free to comment in our blog space.