In 2007, IPC (International Association for the Connection of Electronic Industries) released IPC-9592, "Performance Parameters for Power Conversion Device Equipment. The goal of this standard is to coordinate suppliers' requirements for design, certification, and production testing practices. It includes guidelines for reliability design, design and verification testing, quality procedures, and production manufacturing consistency testing.
In 2010, IPC revised 9592 and released 9592A. In 9592A, the description of HALT has been significantly expanded to include more details of its implementation, including requirements for HALT and recommendations for HASS. These changes come from the clarification and specified expectations of undefined procedures within the industry. It defines the procedures for High Accelerated Life Testing (HALT) and High Accelerated Stress Screening (HASS).
HALT mainly aims to quickly identify design weaknesses and fix them. After improving one weak point, identify and improve the next design weak point, and so on, until the product no longer has any weak points that cause on-site failures. During HALT, the product was subjected to stress exceeding the product specifications Quickly accelerate and identify design weaknesses. HALT is not a pass/fail test, but a series of tests conducted on the product to help improve its reliability.
HALT requires a testing system with repetitive impact (RS) 6 degrees of freedom (DOF) vibration to apply stress to the product in a combination of temperature and vibration environments. The specified vibration level must reach at least 50gRMS and a wide temperature range of at least -80 ° C to+170 ° C. This temperature range needs to be combined with a fast temperature change rate of at least 40 ° C per minute, requiring direct injection of liquid nitrogen for refrigeration. HALT testing requires functional testing of multiple channels capable of monitoring and recording thermocouples, accelerometers, voltage and current measurements.
The functional testing of HALT, although in many cases a unit tested under one stress and not failed can be used for another test, each stress is still defined as the sample size of three units. It includes applying temperature stress and vibration stress separately, and then combining stress, with each stress applied gradually.
In addition to these standard HALT stresses, the input and output load stresses unique to PSU testing are also described. They are first applied together with the temperature limit determined in the temperature step stress, and finally the PSU is subjected to a combination of temperature, vibration, output, and input stresses. These additional stresses make HALT testing more effective for PSU testing than simply using temperature stress and vibration stress.
In HALT, it is not uncommon to repeat testing after implementing corrective measures. Due to the subtle placement points of the accelerometer or software revisions, the test results may be affected, resulting in invalid data during repeated testing.
The actual HALT testing, including identifying the fault modes generated during the testing process, is just the beginning of the work to be completed in HALT. The most important part of the program is to conduct root cause analysis of faults and implement corrective measures. All faults discovered during HALT testing should be analyzed to identify their root causes. The key output of HALT is the fault mode. If these failure modes are ignored, understanding or response is insufficient, most of the benefits of HALT may be lost. As part of the program, it is necessary to ensure correct response to fault modes, and to document the root cause analysis process, as well as the analysis results and corrective measures taken.
The rapid temperature change test chamber (stress screening test chamber ESS) developed by Zhongleng is an instrument and equipment used to simulate the impact of different climate conditions on products and evaluate their reliability and durability. It is to examine the failure caused by the thermal mechanical properties of the product. When the materials that make up the various components of the product have poor thermal matching, or when the internal stress of the components is high, the temperature change test can cause the failure of the product caused by the deterioration of mechanical structural defects. Rapid temperature change testing is a powerful means of environmental stress screening, which can effectively eliminate early failure of products.
Characteristics of rapid temperature change test chamber:
·Autonomous technology: data connection, optional interface for network monitoring
·High operating efficiency: the maximum temperature change rate can reach 15 ℃/min
·More uniform temperature control: advanced technologies such as automatic adjustment of air volume and wind speed, high-speed processing of temperature controllers, and electronic expansion valves are available
·Low noise design: ≤ 65db
·Anti condensation function: optional dry air blower to prevent product condensation
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