Factors causing uneven temperature inside the high and low temperature humid heat test chamber

The high and low temperature damp heat test chamber is the main equipment in temperature and humidity environment testing, mainly used for conducting high and low temperature and humidity tests to evaluate the temperature and humidity resistance of products, so as to ensure that our products can work and operate normally under any environmental conditions. However, if the temperature uniformity exceeds the allowable deviation range during environmental testing in the high and low temperature damp heat test chamber, the data obtained from the test is unreliable and cannot be used as the ultimate tolerance for high and low temperature testing of materials or products. So what are the reasons that can cause temperature uniformity to exceed the allowable deviation range?

1. The differences in the test objects in the high and low temperature humid heat test chamber: If enough test samples that affect the overall internal heat convection are placed in the high and low temperature test chamber, it will inevitably affect the uniformity of the internal temperature to a certain extent, that is, the temperature uniformity. For example, if LED lighting products are placed, the products themselves emit light and heat, becoming a thermal load, which has a significant impact on temperature uniformity.

2. The design issues make it difficult to achieve a uniform symmetrical structure in the internal structure and space of the high and low temperature wet heat test chamber, and an asymmetric structure will inevitably lead to deviations in the uniformity of internal temperature. This aspect is mainly reflected in sheet metal design and processing, such as the design of air ducts, the placement of heating pipes, and the size of fan power. All of these will affect the temperature uniformity inside the box.

3. Due to the different structures of the inner wall of the high and low temperature humid heat test chamber, the temperature of the inner wall of the test chamber will also be uneven, which will affect the heat convection inside the working chamber and cause deviation in the internal temperature uniformity.

4. Due to the different heat transfer coefficients on the front, back, left, right, top, and bottom surfaces of the box wall in the studio, some have threading holes, detection holes, testing holes, etc., which cause local heat dissipation and transfer, resulting in uneven temperature distribution of the box body and uneven radiative convective heat transfer on the box wall, affecting temperature uniformity.

5. The sealing of the box and door is not strict, for example, the sealing strip is not customized and has seams, and the door leaks air, which affects the temperature uniformity of the workspace.

6. If the volume of the test object is too large, or if the position or method of placing the test object in the high and low temperature damp heat test chamber is inappropriate, it will obstruct the air convection inside and also cause significant temperature uniformity deviation. Placing the test product next to the air duct seriously affects the circulation of air, and of course, the uniformity of temperature will be greatly affected.

In summary, all of these points are the main culprits that affect the temperature uniformity inside the high and low temperature humid heat test chamber. We hope that everyone can investigate from these aspects one by one, which will surely solve your confusion and difficulties.

Dear customer:

Hello, our company is a high-quality development team with strong technical strength, providing high-quality products, complete solutions, and excellent technical services to our customers. The main products include walk-in constant temperature and humidity testing chambers, UV accelerated aging testing machines, rapid temperature change testing chambers, walk-in environmental testing chambers, UV aging testers, constant temperature and humidity chambers, etc. Our company adheres to the principle of building a business with integrity, maintaining quality, and striving for progress. With a more determined pace, we continuously climb new heights and contribute to the national automation industry. We welcome new and old customers to confidently choose the products they like. We will serve you wholeheartedly!

Natural Convection Test (No Wind Circulation Temperature Test) and Specification

Home entertainment audio-visual equipment and automotive electronics are one of the key products of many manufacturers, and the product in the development process must simulate the adaptability of the product to temperature and electronic characteristics at different temperatures. However, when the general oven or constant temperature and humidity test chamber is used to simulate the temperature environment, both the oven and constant temperature and humidity test chamber have a test area equipped with a circulating fan, so there will be wind speed problems in the test area. During the test, the temperature uniformity is balanced by rotating the circulating fan. Although the temperature uniformity of the test area can be achieved through the wind circulation, the heat of the product to be tested will also be taken away by the circulating air, which will be significantly inconsistent with the actual product in the wind-free use environment (such as the living room, indoor). Because of the relationship of wind circulation, the temperature difference of the product to be tested will be nearly 10 ° C, in order to simulate the actual use of environmental conditions, many people will misunderstand that only the test machine can produce temperature (such as: oven, constant temperature and humidity test chamber) can carry out natural convection test, in fact, this is not the case. In the specification, there are special requirements for wind speed, and a test environment without wind speed is required. Through the natural convection test equipment (no forced wind circulation test), the temperature environment without fan is generated (natural convection test), and then the test integration test is carried out to detect the temperature of the product under test. This solution can be applied to the actual ambient temperature test of household related electronic products or confined Spaces (such as: Large LCD TV, car cockpit, car electronics, laptop, desktop computer, game console, stereo... Etc.).

The difference of the test environment with or without wind circulation for the test of the product to be tested:

If the product to be tested is not energized, the product to be tested will not heat itself, its heat source only absorbs the air heat in the test furnace, and if the product to be tested is energized and heated, the wind circulation in the test furnace will take away the heat of the product to be tested. Every 1 meter increase in wind speed, its heat will be reduced by about 10%. Suppose to simulate the temperature characteristics of electronic products in an indoor environment without air conditioning, if an oven or a constant temperature and humidity test chamber is used to simulate 35 ° C, although the environment in the test area can be controlled within 35 ° C through electric heating and freezing, the wind circulation of the oven and the constant temperature and humidity test chamber will take away the heat of the product to be tested, making the actual temperature of the product to be tested lower than the temperature in the real state of no wind. Therefore, it is necessary to use a natural convection testing machine without wind speed to effectively simulate the actual windless environment (such as: indoor, non-starting car cockpit, instrument chassis, outdoor waterproof box... Such environment).

Indoor environment without wind circulation and solar radiant heat irradiation:

Through the natural convection tester, simulate the client's actual use of the real air conditioning convection environment, hot spot analysis and heat dissipation characteristics of the product evaluation, such as the LCD TV in the photo not only to consider its own heat dissipation, but also to evaluate the impact of thermal radiation outside the window, thermal radiation for the product may produce additional radiant heat above 35 ° C.

Comparison table of wind speed and IC product to be tested:

When the ambient wind speed is faster, the IC surface temperature will also take away the IC surface heat due to the wind cycle, resulting in faster wind speed and lower temperature, when the wind speed is 0, the temperature is 100℃, but when the wind speed reaches 5m/s, the IC surface temperature has been below 80℃.

Unforced air circulation test:

According to the specification requirements of IEC60068-2-2, in the high temperature test process, it is necessary to carry out the test conditions without forced air circulation, the test process needs to be maintained under the wind-free circulation component, and the high temperature test is carried out in the test furnace, so the test cannot be carried out through the constant temperature and humidity test chamber or oven, and the natural convection tester can be used to simulate the free air conditions.

Description of test conditions:

Test specification for unforced air circulation: IEC-68-2-2, GB2423.2, GB2423.2-89 3.3.1

Unforced air circulation test: The test condition of unforced air circulation can simulate the free air condition well

GB2423.2-89 3.1.1:

When measuring under free air conditions, when the temperature of the test sample is stable, the temperature of the most hot spot on the surface is more than 5℃ higher than the temperature of the surrounding large device, it is a heat dissipation test sample, otherwise it is a non-heat dissipation test sample.

GB2423.2-8 10(Test heat dissipation test sample temperature gradient test) :

A standard test procedure is provided to determine the adaptability of thermal electronic products (including components, equipment level other products) to use at high temperatures.

Test requirements:

a. Testing machine without forced air circulation (equipped with a fan or blower)

b. Single test sample

c. The heating rate is not greater than 1℃/min

d. After the temperature of the test sample reaches stability, the test sample is energized or the home electrical load is carried out to detect the electrical performance

Natural convection test chamber features:

1. Can evaluate the heat output of the product to be tested after power, to provide the best distribution uniformity;

2. Combined with digital data collector, effectively measure the relevant temperature information of the product to be tested for synchronous multi-track analysis;

3. Record the information of more than 20 rails (synchronous record the temperature distribution inside the test furnace, multi-track temperature of the product to be tested, average temperature... Etc.).

4. The controller can directly display the multi-track temperature record value and record curve; Multi-track test curves can be stored on a USB drive via the controller;

5. The curve analysis software can intuitively display the multi-track temperature curve and output EXCEL reports, and the controller has three kinds of display [Complex English];

6. Multi-type thermocouple temperature sensor selection (B, E, J, K, N, R, S, T);

7. Scalable to increase heating rate & control stability planning.

PCB Performs Accelerated Tests of Ion Migration and CAF Through HAST

PCB In order to ensure its long-term use quality and reliability, need to carry out SIR (Surface Insulation Resistance) surface insulation resistance test, through its test method to find out whether the PCB will occur MIG(ion migration) and CAF(glass fiber anode leakage) phenomenon, Ion migration is performed in a humidified state (e.g. 85℃/85%R.H.) with a constant bias (e.g. 50V), the ionized metal moves between the opposite electrodes (cathode to anode growth), the relative electrode is reduced to the original metal and precipitated dendritic metal phenomenon, often resulting in short circuit, ion migration is very fragile, the current generated at the moment of power will make the ion migration itself dissolves and disappears, MIG and CAF commonly used norms: IPC-TM-650-2.6.14., IPC-SF-G18, IPC-9691A, IPC-650-2.6.25, MIL-F-14256D, ISO 9455-17, JIS Z 3284, JIS Z 3197... But its test time is often 1000h, 2000h, for the cyclical products slow emergency, and HAST is a test method is also the name of the equipment, HAST is to improve environmental stress (temperature, humidity, pressure), in the unsaturated humidity environment (humidity: 85%R.H.) Speed up the test process to shorten the test time, used to assess PCB pressing, insulation resistance, and the moisture absorption effect of related materials, shorten the test time of high temperature and humidity (85℃/ 85%R.H. /1000h→110℃/ 85%R.H. /264h), the main reference specifications of PCB HAST test are: JESD22-A110-B, JCA-ET-01, JCA-ET-08.

HAST Accelerated Life Mode:

★ Increase temperature (110℃, 120℃, 130℃)

★ Maintain high humidity (85%R.H.)

Taken the pressure (110 ℃ / / 0.12 MPa, 120 ℃, 85% / 85% / 85% 0.17 MPa, 130 ℃ / / 0.23 MPa)

★ Extra bias (DC)

HAST test conditions for PCB:

1. Jca-et-08:110, 120, 130 ℃/85%R.H. /5 ~ 100V

2. High TG epoxy multilayer board: 120℃/85%R.H./100V, 800 hours

3. Low inductance multilayer board: 110℃/85% R.H./50V/300h

4. Multi-layer PCB wiring, material: 120℃/85% R.H/100V/ 800h

5. Low expansion coefficient & low surface roughness halogen-free insulation material: 130℃/ 85% R.H/12V/240h

6. Optically active covering film: 130℃/ 85% R.H/6V/100h

7. Heat hardening plate for COF film: 120℃/ 85% R.H/100V/100h

Lab Companion HAST High Acceleration Stress Test System (JESD22-A118/JESD22-A110)

The HAST independently developed by Macro Technology fully owns independent intellectual property rights, and the performance indicators can fully benchmark foreign brands. It can provide single-layer and double-layer models and two series of UHAST BHAST. It solves the problem of long-term dependence on imports of this equipment, long delivery time of imported equipment (up to 6 months) and high price. High Accelerated Stress Testing (HAST) combines high temperature, high humidity, high pressure, and time to measure the reliability of components with or without electrical bias. HAST testing accelerates the stress of more traditional testing in a controlled way. It is essentially a corrosion failure test. Corrosion-type failure is accelerated, and defects such as packaging seals, materials and joints are detected in a relatively short time.

 

 

Reliability of Ceramic Substrate

Ceramic PCB (Ceramic Substrate) refers to a special process plate where copper foil is directly bonded to the surface (single or double) of alumina (Al2O3) or aluminum nitride (AlN) ceramic substrate at high temperature. The ultra-thin composite substrate has excellent electrical insulation performance, high thermal conductivity, excellent soldering and high adhesion strength, and can be etched into a variety of graphics like PCB board, with great current carrying capacity. Therefore, the ceramic substrate has become the basic material of high-power electronic circuit structure technology and interconnect technology, which is suitable for products with high caloric value (high-brightness LED, solar energy), and its excellent weather resistance can be applied to harsh outdoor environments.

Main application products: high power LED carrier board, LED lights, LED street lights, solar inverter

Ceramic substrate features:

Structure: Excellent mechanical strength, low warping, thermal expansion coefficient close to silicon wafer (aluminum nitride), high hardness, good processability, high dimensional accuracy

Climate: Suitable for high temperature and humidity environment, high thermal conductivity, good heat resistance, corrosion and wear resistance, UV& yellowing resistance

Chemistry: Lead-free, non-toxic, good chemical stability

Electrical: high insulation resistance, easy metallization, circuit graphics and strong adhesion

Market: Abundant materials (clay, aluminum), easy to manufacture, low price

PCB material thermal characteristics comparison (conductivity) :

Glass fiber board (traditional PCB) : 0.5W/mK, aluminum substrate: 1~2.2W/mK, ceramic substrate: 24[alumina]~170[aluminum nitride]W/mK

Material heat transfer coefficient (unit W/mK) :

Resin: 0.5, alumina: 20-40, silicon carbide: 160, aluminum: 170, aluminum nitride: 220, copper: 380, diamond: 600

Ceramic substrate process classification:

According to the line ceramic substrate process is divided into: thin film, thick film, low temperature co-fired multi-layer ceramic (LTCC)

Thin Film Process (DPC) : Precise control of component circuit design (line width and film thickness)

Thick film process (Thick film) : to provide heat dissipation and weather conditions

Low temperature co-fired multilayer ceramic (HTCC) : The use of glass ceramics with low sintering temperature, low melting point, high conductivity of precious metal co-fired characteristics, multi-layer ceramic substrate) and assembly.

Low temperature co-fired multilayer ceramics (LTCC) : Stack several ceramic substrates and embed passive components and other ics

Thin film ceramic substrate process:

· Pretreatment → sputtering → photoresistance coating → exposure development → line plating → film removal

· Lamination → hot pressing → degreasing → substrate firing → circuit pattern formation → circuit firing

· Lamination → surface printed circuit pattern → hot pressing → degreasing → co-firing

· Printed circuit graphics → lamination → hot pressing → degreasing → co-firing

Ceramic substrate reliability test conditions:

Ceramic substrate high temperature operation: 85℃

Ceramic substrate low temperature operation: -40℃

Ceramic substrate cold and thermal shock:

1. 155℃(15min)←→-55℃(15min)/300cycle

2. 85 ℃ (30 min) please - - 40 ℃ (30 min)/RAMP: 10 min (12.5 ℃ / min) / 5 cycle

Ceramic substrate adhesion: Stick to the surface of the board with 3M#600 tape. After 30 seconds, tear quickly in a 90° direction with the surface of the board.

Ceramic substrate red ink experiment: Boil for one hour, impermeable

Test equipment:

1.High and low temperature humid heat test chamber

2. Three-box gas type cold and heat shock test chamber

 

Structural characteristics of temperature and humidity control box

The full name of the temperature and humidity control chamber is "Constant Temperature and Humidity Test Chamber", which is an essential testing equipment in aviation, automotive, home appliances, scientific research and other fields. It is used to test and determine the parameters and performance of electrical, electronic and other products and materials after high temperature, low temperature, humidity and heat or constant temperature environment changes. It can be mainly divided into "desktop" and "vertical" according to testing requirements and standards, with the difference being the temperature and humidity that can be achieved. The vertical type can be used for low temperature and drying below room temperature, while the desktop type can only be used for temperature and high humidity above room temperature.

Suitable for various small electrical appliances, instruments, materials, and components for wet heat testing, it is also suitable for conducting aging tests. This test chamber adopts the most reasonable structure and stable and reliable control method currently available, making it aesthetically pleasing, easy to operate, safe, and with high precision in temperature and humidity control. It is an ideal equipment for conducting constant temperature and humidity tests.

1) The test box body is in the form of an integral structure, with the refrigeration system located at the lower rear of the box and the control system located at the upper part of the test box.

(2) Inside the air duct interlayer at one end of the studio, there are devices such as heaters, refrigeration evaporators, and fan blades distributed; On the left side of the test box, there is a Ø 50 cable hole, and the test box is a single door (stainless steel embedded door handle)

(3) The double-layer high temperature and anti-aging silicone rubber seal can effectively ensure the temperature loss of the test chamber

 

(4) There are observation windows, frost prevention devices, and switchable lighting fixtures on the box door. The observation window adopts multi-layer hollow tempered glass, and the inner adhesive sheet conductive film is heated and defrosted. The lighting fixtures use imported brand Philips lamps, which can effectively observe the experimental changes in the studio from all angles.

Dear customer:

Hello, our company is a high-quality development team with strong technical strength, providing high-quality products, complete solutions, and excellent technical services to our customers. The main products include walk-in constant temperature and humidity testing chambers, UV accelerated aging testing machines, rapid temperature change testing chambers, walk-in environmental testing chambers, UV aging testers, constant temperature and humidity chambers, etc. Our company adheres to the principle of building a business with integrity, maintaining quality, and striving for progress. With a more determined pace, we continuously climb new heights and contribute to the national automation industry. We welcome new and old customers to confidently choose the products they like. We will serve you wholeheartedly!

Temperature control of solar simulation irradiation test chamber

The test chamber uses an artificial light source combined with a G7 OUTDOOR filter to adjust the system light source to meet the requirements of IEC61646 for solar simulators by simulating the radiation in natural sunlight. The above system light source is used to conduct the IEC61646 photoaging test on the solar cell module, and the temperature on the back of the module needs to be constantly controlled between 50 ± 10℃during the test. Can automatically monitor temperature; Configure a radiometer to control the irradiance of light, ensuring it remains stable at a specified level, while also controlling the testing time.

During the ultraviolet light cycle period in the solar simulation irradiation test chamber, photochemical reactions are usually not sensitive to temperature. But the rate of any subsequent reaction depends on the temperature. The rate of these reactions accelerates with increasing temperature. Therefore, controlling the temperature during UV exposure is crucial. In addition, it is necessary to ensure that the temperature of the accelerated aging test is consistent with the highest temperature at which the material is directly exposed to sunlight. In the solar simulation irradiation test chamber, the UV exposure temperature can be set at any temperature between 50 ℃ and 80 ℃ based on the illuminance and ambient temperature. The UV exposure temperature is adjusted by a sensitive temperature controller and blower system to achieve excellent uniformity in the temperature of this test chamber.

Dear customer:

Hello, our company is a high-quality development team with strong technical strength, providing high-quality products, complete solutions, and excellent technical services to our customers. The main products include walk-in constant temperature and humidity testing chambers, UV accelerated aging testing machines, rapid temperature change testing chambers, walk-in environmental testing chambers, UV aging testers, constant temperature and humidity chambers, etc. Our company adheres to the principle of building a business with integrity, maintaining quality, and striving for progress. With a more determined pace, we continuously climb new heights and contribute to the national automation industry. We welcome new and old customers to confidently choose the products they like. We will serve you wholeheartedly!

UV aging tester testing equipment

The structure of the test chamber is made of corrosion-resistant metal materials, including 8 fluorescent ultraviolet lamps, a water tray, a test sample holder, and temperature and time control systems and indicators.

2. The lamp power is 40W and the lamp length is 1200mm. The range of the uniform working area of the test box is 900 × 210mm.

3. The lights are installed in four rows, divided into two rows. The tubes of each row of lights are installed in parallel, and the center distance of the lights is 70mm.

4. The test sample is fixedly installed at a position 50mm away from the surface of the lamp surface. The test sample and its bracket form the inner wall of the box, and their backs are exposed to cooling air at room temperature due to the temperature difference between the test sample and the air inside the box. To create stable condensation conditions on the surface of the test sample during the condensation stage, the test chamber should generate natural air convection through the outer wall of the chamber and the channel of the test sample at the bottom.

5. Water vapor is generated by a water tray located at the bottom of the heating box, with a water depth not exceeding 25mm, and equipped with an automatic water supply controller. The water tray should be regularly cleaned to prevent the formation of scale.

6. The temperature of the test chamber is measured by a sensor fixed on a black aluminum plate (blackboard) with a width of 75mm, height of 100mm, and thickness of 2.5mm. The blackboard should be placed in the central area of the exposure test, and the measurement range of the thermometer is 30-80 ℃ with a tolerance of ± 1 ℃. The control of lighting and condensation stages should be carried out separately, and the condensation stage is controlled by the heating water temperature.

 

7. The test chamber should be placed in a test room with a temperature of 15-35 ℃, 300mm away from the wall, and should prevent the influence of other heat sources. The air in the test room should not circulate strongly to avoid affecting the lighting and condensation conditions.

Dear customer:

Hello, our company is a high-quality development team with strong technical strength, providing high-quality products, complete solutions, and excellent technical services to our customers. The main products include walk-in constant temperature and humidity testing chambers, UV accelerated aging testing machines, rapid temperature change testing chambers, walk-in environmental testing chambers, UV aging testers, constant temperature and humidity chambers, etc. Our company adheres to the principle of building a business with integrity, maintaining quality, and striving for progress. With a more determined pace, we continuously climb new heights and contribute to the national automation industry. We welcome new and old customers to confidently choose the products they like. We will serve you wholeheartedly!

Drone spraying is a new type of operation method in technological development. High work efficiency, suitable for large-scale agricultural pest control. This is tens or hundreds of times more than physical labor. It can complete tasks that are easy to manually complete, such as forest and mountain forest operations. So how effective are unmanned aerial vehicles used for medicinal purposes on rural land?

Things often have two sides, namely advantages and disadvantages. Drone spraying is no exception, each with its own advantages and disadvantages. The advantage is that the spraying speed is fast. The crop protection drones used for agricultural spraying are generally multi rotor aircraft, much larger than typical small aerial photography drones, with longer endurance and much faster speed. Not to mention, compared to manual spraying, the spraying efficiency of aircraft is hundreds of times higher.

In addition, crop protection drones can adopt two control methods: manual remote control and satellite guided control. Usually, large plots use satellite navigation to control spraying. For land parcels, seamless spraying can be achieved without losing crops. No matter how slow and careful manual spraying is, there will always be omissions at the beginning, which machines cannot match

The spraying quality is also very high. The principle of drone spraying is to install the medicine box on the body of the drone, open the valve after the drone takes off to discharge the medicine, and then use the strong wind generated by the high-speed rotation of the drone blades to atomize and blow down the medicine. Due to the strong atomization and falling of drugs by the wind, the adhesion and diffusion rate of drugs is higher than traditional manual spraying, so the effect of spraying drugs in this way is higher than manual spraying.

In fact, there are many potential safety hazards hidden in drones, and some issues have also been documented in previous reports. For example, during the process of spraying pesticides, if no pesticides are sprayed into the river, all organisms in the river will be poisoned. A clear river on the horizon is easily destroyed. If there are artificially cultivated aquatic products in the Tianbian River, it is easy to become an economic dispute if such a problem is encountered.

In addition, the promotion of drone pesticide spraying in modern rural areas is insufficient, and there are many regulatory loopholes. Relevant departments need to introduce policies to guide and manage it correctly, avoid irreparable losses caused by technical errors, and ensure the safety of drone pesticide spraying.

Therefore, if rural areas want to implement drone pesticide spraying, corresponding technical support must be provided first, and drone training must be provided to farmers to ensure that they use drones in the correct situations, thereby avoiding many problems. As long as they have sufficient technology, they must maintain consistency in the spraying process.

In addition, due to its fast speed, the effect of uniform application is poor. The drone spray passes through instantly, making it difficult to mix evenly and thoroughly. The only way to overcome the problem of uneven and thorough beating is to increase the concentration of the liquid medicine, thereby increasing the investment cost. For example, when spraying drugs in cotton fields, UAV spray can not kill cotton bollworm in cotton buds, aphids on the back and bottom of leaves.

Only by absorbing crops can endogenous pests be dealt with, and some pests may not be killed by endogenous agents but can only be dealt with through contact. The main disadvantage of manual spraying is slow speed, making it difficult to spray at high altitudes. It has the advantage of uniform application, which can evenly and thoroughly hit crops up and down. Save technical solutions.

Although there are many advantages to using drones to spray pesticides, such as high efficiency and good quality, there are also certain limitations. For example, it depends on weather conditions. It cannot take off in bad weather and cannot work all day. It is only suitable for the vast northern regions, while the southern mountainous and hilly areas are not particularly suitable for large-scale operations.

Generally speaking, using drones to spray pesticides on farmland is very cost-effective. Short time, uniform spraying, and affordable price. Therefore, more and more farmers are gradually choosing to use drones to spray pesticides on crops. There are also many smart young people who see the vast prospects of this industry, specializing in drone spraying, and the profits are still considerable.

Drones are a manifestation of high-tech technology applied in agriculture, and are a progressive product of the combination of modern technology and traditional agriculture. From an efficiency perspective, it is indeed higher than manual spraying. From a practical perspective, it cannot be compared to manual operation. Drones can only spray on the front of crops, but cannot spray on the back of crops.

When spraying pesticides, unmanned aerial vehicles also pay attention to the weather. Due to strong winds and heavy fog, it is impossible to operate, and manual operation can completely ignore this situation. Therefore, unmanned operation has its own advantages, and manual operation also has its advantages, which should be complementary. We cannot veto drones with one vote. We should view new things from a developmental perspective. Although there are drawbacks to drone operation, it is an assistant for the future development of agriculture.

The development process of agricultural drones can be divided into several important stages, each with its unique characteristics and milestones. ‌

Initial stage: Concept machine and demonstration machine

Conceptual stage (2010-2012): This stage mainly involves the dissemination of concepts, and the operational capabilities of crop protection drones are very limited, mainly used for small-scale demonstrations and testing within the industry.

Demonstration stage (2013-2015): With the advancement of technology, crop protection drones began to be demonstrated in farmland. Although their operational capabilities have improved, they have not yet reached the standard for large-scale application.

Development stage: trial application and batch application

Trial application stage (2016-2017): Plant protection drones began to be practically applied in farmland, and more and more practitioners entered this industry, further verifying the industry model and operational capabilities.

Batch application stage (2018-2020): Plant protection drones have the ability to make money, their business models and service capabilities are gradually maturing, and more social resources are entering this industry.

Mature stage: Wide application and future trends.

Widely used stage (2021 present): Plant protection drones have been fully accepted by the industry and cannot be replaced. All social resources know their purpose and have become a mature industry.

Future trend: Plant protection drones will further become intelligent and precise, improving operational efficiency and effectiveness while reducing costs and meeting the diverse needs of farmers.

Technological progress and market application

The development of crop protection drone technology is also accompanied by the continuous expansion of the market. Abroad, Japan developed the world's first crop protection drone in 1987 and currently has over 5000 in stock. Since 2004, China has been researching and promoting unmanned aerial vehicles (UAVs) for crop protection. By 2019, the number of UAVs in operation had reached 55000, covering an area of 33 million hectares. The advancement of policies and technology has also driven the rapid development of crop protection drones in China.

Key technologies and market acceptance

The key technologies of crop protection drones include power systems, flight control, and spraying systems. In the early days, it was mainly oil powered aircraft, but with the rise of electric drones, electric drones gradually became the mainstream in the market due to their cost-effectiveness and environmental friendliness. In terms of market acceptance, farmers have gradually shifted from a wait-and-see attitude to acceptance and recognition, and crop protection drones have become an indispensable tool in agricultural production.

Electromagnetic acoustic transducer testing technology‌ has broad prospects for development in the future, with significant advantages and potential application value. As an emerging non-destructive testing technology, this technology has the characteristics of high precision, no need for coupling agent, non-contact, suitable for high-temperature testing, and easy to excite various ultrasonic waveforms. Therefore, it has received widespread attention and attention in the field of industrial testing. With the advancement of science and technology and the increasing demand for precise monitoring, electromagnetic acoustic transducer testing technology is expected to play a more important role in various fields and further promote the development and progress of human society.

The future development of electromagnetic acoustic transducer testing technology is mainly reflected in the following aspects:

‌High temperature detection capability‌: By configuring high-temperature probes, electromagnetic acoustic transducer testing technology can adapt to high-temperature on-site testing up to 800°C, and automatically compensate for changes in sound velocity to make the thickness measurement more accurate. This feature makes it have great potential in high-temperature industrial applications.

‌Rich application scenarios‌: By adopting electromagnetic acoustic transducers of different configurations, the excitation and reception of various ultrasonic waveforms can be realized, which greatly enriches the application scenarios of electromagnetic acoustic transducer testing technology. This not only improves the detection efficiency, but also enables the technology to adapt to more industrial detection needs.

‌Possibility of online monitoring‌: electromagnetic acoustic transducer testing technology does not require the use of coupling agents, which makes it possible to achieve online monitoring. Online monitoring can monitor the status of industrial equipment in real time, detect potential problems in a timely manner, and thus improve production efficiency and safety‌.

Although electromagnetic acoustic transducer testing technology still has problems such as low transducer conversion efficiency and poor detection effect on coarse-grained materials that need further research and development, these problems will be gradually solved with the continuous advancement and improvement of technology. Overall, the future development prospects of electromagnetic acoustic transducer testing technology are very optimistic, and it will bring more innovations and breakthroughs to the field of industrial testing‌.

‌Electromagnetic acoustic transducer testing technology‌ has broad development prospects in the future and has significant advantages and potential application value. As an emerging non-destructive testing technology, this technology has the characteristics of high precision, no need for coupling agents, non-contact, suitable for high-temperature testing, and easy to excite various ultrasonic waveforms. Therefore, it has received widespread attention and attention in the field of industrial testing. With the advancement of science and technology and the increasing demand for precise monitoring, electromagnetic acoustic transducer testing technology is expected to play a more important role in various fields and further promote the development and progress of human society‌.

The future development of electromagnetic acoustic transducer testing technology is mainly reflected in the following aspects:

‌High temperature detection capability‌: By configuring high temperature probes, electromagnetic acoustic transducer testing technology can adapt to high temperature on-site detection up to 800℃, and by automatically compensating for changes in sound velocity, the thickness measurement value is more accurate. This feature makes it have great potential in high temperature industrial applications‌.

‌Rich application scenarios‌: By adopting electromagnetic acoustic transducer of different configurations, various ultrasonic wave types can be excited and received, which greatly enriches the application scenarios of electromagnetic acoustic transducer testing technology. This not only improves the detection efficiency, but also enables the technology to adapt to more industrial detection needs‌.

‌Possibility of online monitoring‌: electromagnetic acoustic transducer testing technology does not require the use of coupling agents, which makes it possible to achieve online monitoring. Online monitoring can monitor the status of industrial equipment in real time, detect potential problems in time, and thus improve production efficiency and safety‌3.

Although electromagnetic acoustic transducer testing technology still has problems such as low transducer conversion efficiency and poor detection effect on coarse-grained materials that need further research and development, these problems will be gradually solved with the continuous advancement and improvement of technology. Overall, the future development prospects of electromagnetic acoustic transducer testing technology are very optimistic, and it will bring more innovations and breakthroughs to the field of industrial testing.