The temperature and humidity three comprehensive vibration test box (hereinafter referred to as the "three comprehensive test box") is a type of integrated testing equipmentTemperature, humidity, vibrationA reliability testing device that integrates three types of environmental stresses, capable of simulating complex environments that products may encounter during transportation, storage, or use (such as high temperature and humidity+vibration, low temperature and low humidity+random vibration, etc.), used to verify the durability, structural strength, functional stability, and failure mechanism of products. Its selection needs to be closely integratedProduct Features(such as size, weight, material, working condition) andtest objective(such as standard compliance, failure modes, environmental conditions), the following will explain the core parameters, key considerations, and selection steps.

1、 Clarify core testing requirements: product features and testing objectives

Before selecting, two core issues need to be clarified:

　　1. Product Features​

　　physical parametersProduct dimensions (length x width x height), weight (determining the load-bearing capacity of the test chamber and vibration table), center of gravity position (affecting vibration uniformity);

　　Materials and StructuresDoes it contain precision electronic components (sensitive to moisture and vibration), brittle materials (sensitive to impact), and flexible structures (prone to resonance);

　　work statusWhether power is required during testing (such as load testing) and whether heat is generated (requiring additional heat dissipation design);

　　Environmental sensitivityThe tolerance limit for temperature/humidity (such as the working temperature range of the chip -40 ℃~85 ℃, humidity sensitivity level MSL1~6).

　　2. test objective​

　　Standard complianceWhat industry standards need to be met (such as GJB150 (equipment), IEC60068 (electrical and electronic), ISO16750 (automotive parts), MIL-STD-810 (US military standard));

　　Failure ModeWhat kind of failure should we focus on? (For example, fatigue fracture of solder joints requires high-frequency vibration+temperature cycling, and coating detachment requires wet heat aging+vibration);

　　environmental conditionsThe temperature and humidity range to be simulated (such as -70 ℃~150 ℃, 10%~98% RH), vibration type (sine/random/mixed), vibration magnitude (displacement/velocity/acceleration), and duration (such as 1000 hour durability test).

2、 Core parameters and selection points of the three comprehensive test chamber

The performance of the three comprehensive test chambers is determined byTemperature and humidity system、Vibration system、Comprehensive control capabilityThe three major modules determine the need to match the requirements one by one.

（1） Temperature and Humidity System: Range and Uniformity of Temperature and Humidity

The temperature and humidity system is the foundation of simulating the environment, and the following parameters need to be focused on:

parameter​	Key selection points​
temperature range​	The usage/storage temperature of the product needs to be covered (such as -55 ℃~125 ℃ for aviation electronic equipment and -40 ℃~85 ℃ for ordinary consumer electronics). Pay attention to the "effective working temperature range" (non limit value, ensuring temperature change rate).
humidity range​	Usually 10%~98% RH (some models can reach 5%~99% RH), attention should be paid to the "dew point temperature" (the upper limit of humidity at low temperatures is limited by condensation, such as a maximum humidity of about 30% RH at -40 ℃).
Temperature change rate​	Key indicators (such as 10 ℃/min, 20 ℃/min) affect testing efficiency (such as rapid temperature change testing requiring ≥ 15 ℃/min). It needs to be confirmed whether it is the "average rate" or the "peak rate" (in actual testing, it is mostly the average).
Temperature and humidity uniformity​	The better the uniformity (such as ± 0.5 ℃/± 2% RH), the more reliable the test results will be. Please refer to the calibration report provided by the manufacturer (usually tested under no-load/full load conditions).
Humidity control accuracy​	Precision testing (such as material aging) requires high precision (within ± 1% RH), while ordinary reliability testing requires ± 3% RH.

（2） Vibration system: vibration type, magnitude, and load capacity

The vibration system is the core of simulating mechanical stress and should be selected based on the vibration sensitivity characteristics of the product

parameter​	Key selection points​
Vibration type​	-Sinusoidal vibrationSimulate continuous excitation of a single frequency (such as steady-state vibration of rotating machinery), suitable for finding resonance points; -random vibrationSimulate the composite vibration in real environments (such as vehicle driving, air transportation), which is closer to actual working conditions; -Impact/collisionShort term high-energy excitation (such as falls and collisions) requires additional impact modules (some of which are integrated into the three comprehensive boxes).
frequency range​	Covering the vibration frequencies that the product may encounter (such as automotive components typically ranging from 5Hz to 2000Hz, and aerospace equipment may extend to 5000Hz). Attention should be paid to the displacement capability (large amplitude) in the low-frequency range (≤ 20Hz) and the acceleration capability (small displacement) in the high-frequency range (≥ 1000Hz).
Vibration level​	-Displacement: usually 0-51mm (sinusoidal vibration); -Acceleration: usually 0~100g (random vibration power spectral density PSD needs to match the standard, such as the PSD curve of aircraft equipment specified in GJB150.16A); -Need to confirm the 'rated thrust' (the output of the vibration table, positively correlated with the load weight: thrust=load weight x acceleration).
Vibration table load capacity​	Must be ≥ product weight (including fixtures and jigs), with a reserved margin of 10%~20% (to avoid overloading and damage to the vibration table). If the center of gravity of the product is offset, the "overturning moment" needs to be checked (the vibration table needs to have the ability to resist eccentric loads).
Vibration direction​	Optional single axis (X/Y/Z), dual axis, or three-axis vibration (three-axis is closer to the actual multidimensional vibration environment, but at a higher cost).

（3） Comprehensive control capability: synchronicity, programming, and scalability

The key to the three comprehensive experiments isSynchronous control of temperature, humidity, and vibration(If temperature changes and vibrations start and stop simultaneously to avoid testing errors caused by timing deviations), attention should be paid to:

parameter​	Key selection points​
Synchronization control accuracy​	The start/stop/change of temperature, humidity, and vibration must be strictly synchronized (such as ± 0.1s level), otherwise it is impossible to simulate the real coupling environment (such as bumps and high temperatures when a car passes over speed bumps).
Programming and Sequence Control​	It is necessary to support the writing of complex testing programs (such as temperature cycling first, then random vibration, and finally wet heat maintenance), and can set conditional triggers (such as starting vibration when the temperature reaches 85 ℃).
Data collection and monitoring​	Integrated sensors (temperature, humidity, vibration acceleration/displacement) are required for real-time monitoring, supporting data recording and export (in accordance with standard test report formats).
scalability​	Does it support the installation of additional features (such as salt spray, dust, and lighting) and linkage with external devices (such as product power supply and signal acquisition device).

3、 Other key considerations

　　1. Sample size and installation method​

The size of the inner cavity of the test box should be ≥ the size of the sample (including fixtures), and at least 10cm of operating space should be reserved (for easy wiring and observation);

The size of the vibration table surface needs to match the sample fixture (such as circular/square surfaces, do they need to be fixed with T-shaped slots);

If the sample needs to be tested with electricity, it is necessary to confirm whether there are sufficient lead holes (diameter, quantity) and anti condensation design inside the box (to avoid cable water vapor short circuit).

　　2. Safety and Compliance​

Electrical safety: Compliant with CE, UL and other certifications, equipped with over temperature protection, over voltage protection, and leakage protection;

Mechanical safety: The vibration table has an emergency stop button and anti pinch design;

Environmental requirements: Whether the refrigerant complies with RoHS (such as fluorine free environmentally friendly refrigerants).

　　3. Cost and Service​

Budget: The price of the three comprehensive test chamber is relatively high (hundreds of thousands to millions), and it is necessary to balance performance and cost (if not necessary, three-axis vibration should not be selected);

After sales: Manufacturers need to provide calibration services (regular calibration of temperature, humidity, and vibration sensors) and fault response time (such as on-site visits within 24 hours);

Energy consumption: Pay attention to cooling/heating power and vibration table power consumption (high long-term electricity costs).

4、 Summary of Selection Steps

　　Clarify requirementsSort out the physical parameters, environmental sensitivity characteristics, and testing objectives (standards, failure modes, environmental conditions) of the product;

　　Match parametersFilter core parameters such as temperature and humidity range, vibration type/level, and load capacity based on requirements;

　　Verify compatibilityConfirm that the sample size and installation method match the inner cavity/tabletop of the test chamber, and evaluate whether the synchronous control and programming capabilities meet the testing sequence;

　　Examine manufacturers and servicesSelect manufacturers with industry cases (such as military, automotive, electronics), verify calibration reports and after-sales support;

　　test verificationWhen conditions permit, manufacturers are required to demonstrate the testing process with similar samples to verify data accuracy and control stability.

Example: Selection scenario of a car navigation system

　　Product FeaturesSize 200 × 150 × 50mm, weight 1kg, including PCB board (sensitive to temperature -30 ℃~70 ℃, humidity ≤ 85% RH), simulating vibration during car driving (5Hz~500Hz, random vibration PSD=0.02g ²/Hz);

　　test objectiveCompliant with ISO16750-3 (Environmental Testing for Road Vehicle Electrical and Electronic Equipment), to verify the stability of screen display under high temperature, high humidity, and vibration.

　　Selection plan：

Temperature and humidity range: -40 ℃~100 ℃ (covering -30 ℃~70 ℃), 10%~95% RH (dew point temperature verification: humidity ≤ 30% RH at -40 ℃);

Vibration system: Random vibration of 5Hz~500Hz, maximum acceleration of 10g (thrust ≥ 1kg × 10g=98N, choose 100N thrust vibration table), table size of 300 × 300mm (compatible with navigation fixture);

Integrated control: Supports synchronous programming of temperature, humidity, and vibration (such as holding at 40 ℃/85% RH for 2 hours → random vibration for 4 hours → -20 ℃/60% RH cycle), with an internal cavity size of ≥ 400 × 400 × 400mm (reserved fixture space).

　　ConclusionThe selection of the three comprehensive test chambers should be based on product characteristics and guided by testing objectives, with a focus on matching temperature and humidity ranges, vibration levels, and synchronous control capabilities. The suitability, safety, and service of the samples should also be comprehensively considered to ensure the effectiveness and reliability of the testing.