How to choose the temperature change rate of the high and low temperature test chamber according to the testing purpose?

The core logic for selecting the temperature change rate of the high and low temperature test chamber based on the testing purpose is to match the rate with the core goal of the test, while also considering the characteristics of the sample and the reliability of the data. The following disassembly and selection methods are based on different testing purposes, with specific cases and practical suggestions attached:

1、 Classification of testing purposes and selection of testing rates

1. Simulate a real usage environment

Core requirement: To reproduce the temperature change process of the product in practical application scenarios, ensuring that the test results reflect the true performance of the product.

Recommended speed: 0.5~2 ℃/min (very close to the natural environment temperature rate), and can be relaxed to 3 ℃/min in some scenarios.

Typical Case

Power battery test: Simulate the cooling process from garage (10 ℃) to outdoor (-20 ℃) in winter, with a speed of 1 ℃/min;

Mobile phone/outdoor camera: Simulate the temperature rise from indoors (25 ℃) to outdoors in summer (40 ℃), selecting 2-3 ℃/min;

Automotive components: Simulate the temperature change of the entire vehicle from winter in the north (-30 ℃) to summer in the south (40 ℃), with a speed of 1 ℃/min;

Precautions

For plastic shells and thick walled components, a lower rate (0.5~1 ℃/min) should be selected to ensure synchronous temperature changes inside and outside the sample;

The running motor and charging battery need to be equipped with the "thermal load compensation function" of the equipment to offset the interference of the sample's own heating on the temperature rate.

2. Accelerated aging/batch quality inspection

Core requirement: Shorten the testing cycle and quickly verify the long-term temperature resistance of the product.

Recommended speed: 3-5 ℃/min, some high-temperature resistant samples can be relaxed to 8 ℃/min.

Typical Case

Plastic component aging test: Conventional natural temperature aging takes several months, and the testing cycle can be compressed to several days at a rate of 5 ℃/min;

Mass production sampling of consumer electronics: quickly complete high and low temperature cycle testing at a rate of 3 ℃/min to ensure that there are no obvious temperature change defects in the batch of products;

Reliability testing of capacitors/resistors: Conduct 100 cycles of high and low temperatures at a rate of 4 ℃/min to quickly screen for non-conforming products.

Precautions

The speed should not exceed 5 ℃/min, otherwise the product may fail prematurely due to thermal stress overload and be misjudged as unqualified;

A set of comparative tests with a standard rate of 1 ℃/min should be retained to verify the validity of the acceleration test results.

3. Screening for structural/material defects

Core requirement: Expose hidden structural or material defects in the product through strong thermal stress.

Recommended speed: ≥ 10 ℃/min temperature shock level speed, requires a dedicated fast temperature change box or cold and hot shock box, * * scenes can choose 15-20 ℃/min.

Typical Case

Chip packaging testing: Quickly switch between -40 ℃~85 ℃ at a rate of 15 ℃/min to expose the bonding defects between the packaging adhesive and the chip;

Power battery module testing: Conduct temperature shock at a rate of 10 ℃/min to screen for modules with poor welding and cracked terminals;

Automotive headlight testing: Verify the sealing reliability of the lampshade and lamp holder by using a cold and hot shock rate of 12 ℃/min.

Attention: This only applies to "defect screening" and cannot be used to simulate real usage environments; Special equipment needs to be selected.

4. Certification compliance testing

Core requirement: Comply with national/industry standards to ensure that test reports are recognized.

Recommended speed: Select strictly according to the corresponding standard requirements.

Typical Case

Electrical product GB/T 2423.22 certification: choose 1 ℃/min or 3 ℃/min;

GB/T 31484 certification for power batteries: select ≤ 2 ℃/min;

ISO 16750 certification for automotive parts: choose 1-3 ℃/min.

Precautions

Before testing, it is necessary to confirm the speed accuracy of the equipment and keep calibration records;

Do not increase the speed without authorization in order to save time, otherwise the report will be deemed invalid.

5. Product ultimate performance verification

Core requirement: Test the survival ability of the product under sudden temperature changes.

Recommended speed: 5-10 ℃/min between acceleration testing and temperature shock.

Typical Case

Polar scientific research equipment: rapidly reduce the temperature to -60 ℃ at a rate of 8 ℃/min to verify the startup performance of the equipment;

Communication equipment: Use a rate of 10 ℃/min to raise the temperature from room temperature to 70 ℃ and test the operational stability at high temperatures.

Precautions

Belonging to 'extreme testing', the results are only used to evaluate the product's ability to withstand the environment and do not represent daily performance;

It is necessary to confirm the design limit temperature of the product in advance to avoid direct damage to the sample due to excessive speed.

2、 Selection Decision Process

1. Clarify the core testing objectives;

If it is for certification purposes, select the speed directly according to the standard;

3. If for other purposes, conduct preliminary selection according to the recommended scope mentioned above;

4. Adjust according to the characteristics of the sample;

5. Confirm equipment capability;

6. Verify the rationality of the speed.

3、 Guide to Avoiding Pits

The faster the speed, the better, it can save time "→ Only accelerating testing/defect screening can be fast, simulating real environments needs to be slow, otherwise the data will be distorted;

All samples use the same rate "→ The low thermal conductivity sample (plastic) and the heating sample (battery) need to be adjusted separately;

Ordinary high and low temperature chambers can perform temperature shock. The speed of ordinary chambers is ≤ 5 ℃/min, and special equipment is required for shock testing.