As the core equipment for environmental reliability testing, the detection accuracy of the three comprehensive test box directly affects the accuracy of product validation results. This article combines industry practice and standard requirements to systematically explain the standardized process and key verification methods for submitting testing accuracy, helping users achieve reliable and controllable testing data.

1、 Pre inspection preparation before accuracy submission

1. Equipment status verification

Confirmation of calibration validity periodCheck the calibration certificates of temperature and humidity sensors to ensure complianceIEC 60068-1standard specified12Within the validity period of one month.

Function self check: Execute the device's built-in system diagnostic program, focusing on checking whether the response curves of the cooling, heating, and humidification modules are smooth and without fluctuations. For example, a military laboratory found that the response delay of the humidification system exceeded30In seconds, the water circuit solenoid valve was replaced in a timely manner to avoid humidity control deviation.

Environmental adaptability adjustment: Adjust equipment parameters based on laboratory environmental conditions such as altitude and power supply stability. In high-altitude regions (altitude)>2000m）It is necessary to reduce the operating frequency of the compressor to prevent overload protection.

2. Standard configuration

Temperature verification: Select platinum resistance thermometer (accuracy)±0.05℃）As a reference standard, its range should cover the working range of the test chamber（-70℃~+180℃）.

Humidity verification: using a cold mirror dew point meter (accuracy)±1.5%RH）Replace traditional dry wet bulb sensors and eliminate the influence of water quality on measurement results.

Space layout: PressGB/T 5170.2The standard requirement is to arrange at the three equal points on the diagonal of the studio9A temperature measurement point, height from the bottom of the box1/3Here.

2、 Implementation process of precision testing

1. Static accuracy verification

Temperature detection: Set the test chamber to25℃The55℃The85℃Three temperature points, stable operation2After hours, record the deviation between the standard and the displayed values of the equipment. Actual test data from a certain automotive electronics company shows that85℃High temperature point, deviation of high-quality equipment should≤±0.8℃.

Humidity detection: in40℃/85%RHThe30℃/65%RHContinuous monitoring under two typical operating conditions6The humidity fluctuation range should be controlled within hours±2.5%RHWithin.

2. Dynamic accuracy verification

Temperature change rate test: to5℃/minThe speed from25℃Rise to85℃Record the maximum deviation between the actual temperature curve and the set value. Industry standards require that during the temperature change process, any10Within a minute interval, the temperature overshoot shall not exceed the set value±2%.

Humidity recovery test: in85%RHSuddenly switching to30%RHMeasure the humidity to drop to the target value90%Required time. The recovery time of high-quality equipment should be≤15minute

3. Uniformity verification

Space temperature difference detection: in9Simultaneously record temperature values at each point and calculate the difference between the maximum and minimum values.GB/T 5170.5According to the standard, the temperature difference between any two points in the work area shall not exceed the temperature deviation1.5Twice.

Humidity gradient detection: using a distributed humidity sensor network to verify the vertical direction (from the bottom of the box)0.3m/1.0m/1.7m）The humidity difference. In30℃/65%RHUnder working conditions, typical uniformity should≤±3%RH.

3、 Submission Specification for Accuracy Verification Files

1. Preparation of testing report

Data record sheet: It should include test conditions (temperature and humidity points, stabilization time), standard readings, equipment display values, deviation calculations, etc12Core parameters of the item.

Uncertainty analysis: according toJJF 1059.1Standards, quantifying the impact of environmental factors (such as laboratory temperature fluctuations), standard instrument errors, personnel operations, etc. on test results. For example, a report from a testing institution shows that the uncertainty of temperature measurement mainly comes from the calibration error of the standard instrument (contribution rate)65%）Uniformity of equipment space (contribution rate)25%）.

Compliance assessment: Clearly label the test results andGB/T 2423TheIEC 60068Based on the compliance conclusion of the standards, analyze the reasons for the out of tolerance items and propose improvement suggestions.

2. Third party authentication support

CNASAccreditation laboratory testing: choose to pass the China National Accreditation Service for Conformity Assessment（CNAS）The certified laboratory conducts accuracy verification, and its testing report has international mutual recognition effect.

Equipment comparison test: Conduct cross validation with devices of the same type, such as comparing the test chamber with a high-precision constant temperature and humidity chamber under the same operating conditions to verify the consistency of the results. A semiconductor company found through this method that the humidity control accuracy of its test chamber is better than the industry standard requirements18%.

4、 Continuous precision assurance mechanism

1. Preventive Maintenance Plan

Establish a quarterly maintenance system, focusing on checking key indicators such as refrigerant pressure, humidifier scale deposition, and electrical connection reliability. After implementing preventive maintenance, the annual equipment failure rate of a certain aviation enterprise has decreased42%.

2. During the verification process

Between two formal calibrations, use standard weights (temperature) and saturated salt solution (humidity) for rapid verification. For example, monthly verification using lithium chloride saturated solution40%RHEnsure humidity control stability at the operating point.

3. Personnel Skill Certification

The operator needs to pass throughISO 17025Internal auditor training to master core skills such as equipment calibration, data processing, and exception handling. According to statistics from a third-party testing agency, the error caused by the operation of professionally trained personnel has been reduced67%.

Through a standardized accuracy submission process and scientific verification methods, the three comprehensive test box can achieve a reasonable range of uncertainty control in the detection data (temperature)≤±1.0℃, humidity≤±3.0%RH）. It is recommended that users establish equipment accuracy records, record each testing result and improvement measures, and form a continuous improvement quality management loop. With the continuous improvement of product reliability requirements in intelligent manufacturing, precise environmental simulation testing will become a key link to ensure product quality.