EMPF is pleased to announce the addition of a 20,000 g shock testing machine (for test loads less than 80 lbs.) to its array of reliability and failure analysis services offered to DoD and industry. The shock testing machine is part of a broad program initiated at EMPF to assess and develop new packaging techniques for electronics designed for use in precision guided munitions and other high shock environments. In these programs electronics modules are routinely subjected to impacts in the range of 10,000 – 50,000g. While such testing is not a substitute for the expensive field testing of military systems, it is important to have low cost screening methods that quickly root out components and packaging techniques that cannot withstand this severe environment. Impact testers provide a quick and effective means for performing such screening in a controlled environment. When combined with other environmental tests, lifetime assessments can be made.

Shock and vibration testing services perform testing on finished products or components using shock, sine, and other dynamic test conditions. Typically a battery of tests is performed in accordance with published standards from organizations such as Underwriters Laboratories (UL), American Society for Testing of Materials (ASTM), and International Safe Transit Association (ISTA). Shock and vibration testing for military equipment is covered under MIL-STD-810F and 901D. These tests may be used to determine the effects of aging, bounce, creep, decompression, fatigue, fire, humidity, pyrotechnic shock, radiation, sterilization, stress, thermal cycling, ultraviolet radiation and weathering. Examples of products that might require testing include: aerospace and avionics equipment, automotive parts, electronics and microelectronics, electrical distribution devices, combustion and hazardous location equipment, industrial machinery, and instrument sensors. Shock and vibration test testing may also be required for valves and pumps, pneumatic and hydraulic systems, healthcare and medical devices, batteries, and energy products.

Shock testing of electronic assemblies as defined by both MIL-STD- 810F (Method 516.5) and JESD22 standards has precipitated a demand from the electronic industry for reliable testing sources to meet the spec requirements. As important as the equipment and facilities are in contributing to shock test quality, it is equally critical that the nature of test be understood to provide the correct operating conditions, and optimal response.

As currently specified in the MIL-STD-810F, materials or assemblies weighing less than 20 lbs are required to undergo drop heights of at least 30 inches, at velocities of 304 in/s to simulate the required material functionality before, or after being inadvertently dropped. This can be an individual electronic package, module, or circuit board, for example, prior to the full assembly or integration. Once the full box assembly is completed, an additional transit drop requirement may be needed which requires multiple drops at a minimum of 4 ft. The shock tester should have the ability to produce the substantial displacement and velocity requirements needed to produce the minimally required trapezoidal pulse shape. For certain military applications, where forces can exceed 10,000 g, the complexity of the transient waveform requires a shock response spectrum analysis capability that is needed to ascertain more complex transient shock events. Versatility is an important element in the capability of the shock system and should include features to determine half sine, trapezoidal, and terminal peak saw tooth pulses that can generate reproducible results.

EMPF has responded to the need for reliable shock analysis by building a shock test facility to house the Lansmont Model 23 Shock Test System shown in Figure 2-1. The System features an electronic hoist lifting system capable of producing drops from a 96 inch height with velocity changes of up to 432 inches/sec. The shock pulse can produce durations from 0.2 msec to 60 msec at forces of less than 5000 g, and time durations of less than 0.1 msec for shock levels approaching 30,000 g. This model is designed for testing products weighing up to 80 lbs, using a 9” x 9” high strength aluminum shock table. To attain high impact levels, the Model 23D machine is outfitted with a dual mass shock amplifier. The data is transmitted to a Partner 3 data acquisition system for analysis, where a detailed Shock Response Spectrum can be produced. In addition, the software can perform an FFT analysis, a shock response animation in both 2D and 3D modes, a shock response analysis with programmable model Fn and damping, and tolerance band overlays with selectable Mil-Spec and programmable pulse parameters.

To reduce the amount of background noise, the Lansmont system is fitted with a floating seismic reaction mass, which can isolate the shock energy to the surrounding environment. Various buffering materials can be inserted between the shock base and the floating seismic reaction mass to produce a range of transient duration times at any given drop height. As the material quality and thickness of the buffering pads changes, the displacement of the sample will increase or decrease, producing changes in the amplitude and duration of the shock pulse. The accelerometer is also critical for producing reliable and reproducible data and should be rated for the amount of potential force that the sample may encounter. The shock tester is equipped with an ICP accelerometer that is rated to 50,000 g, and can be retro-fitted to mount various assemblies. Fixtures can be produced that can generate data on all three orthogonal axes, which is a requirement in the MIL STD testing.

To complement the impact test, EMPF also offers vibration testing using a Labworks vibration table. Shock and vibration testing can be combined with storage in environmental chambers including thermal cycling or thermal shock, temperature/humidity storage, HAST, saltfog, or high temperature storage. ACI affords the user a comprehensive level of support including additional materials and failure analysis services. Failure analysis can be performed invasively (cross sectional analysis) or non-invasively (X-ray imaging). Our experienced staff is knowledgeable in both the technical and quality aspects of producing, interpreting, reporting, and combining shock data with other reliability testing that is appropriate to your needs.