Tablet Reliability Test
A Tablet Computer, also known as a Tablet Personal Computer (Tablet PC), is a small, portable personal computer that uses a touch screen as its basic input device. It is an electronic product with strong mobility, and it can be seen everywhere in life (such as waiting stations, trains, high-speed trains, cafes, restaurants, meeting rooms, suburbs, etc.). People carry only simple coat protection or even no, in order to facilitate use, the design reduces the size, so that it can be directly placed in the pocket or handbag, backpack, but the tablet computer in the process of moving will also experience many environmental physical changes (such as temperature, humidity, vibration, impact, extrusion, etc.). Etc.) and natural damage (such as ultraviolet light, sunlight, dust, salt spray, water droplets... It will also cause artificial unintentional injury or abnormal operation and misoperation, and even cause failure and damage (such as: household chemicals, hand sweating, falling, terminal insertion and removal too much, pocket friction, crystal nails... These will shorten the life of the tablet computer, in order to ensure the reliability of the product and extend the service life to improve, we must carry out a number of environmental reliability test projects on the tablet computer, the following relevant tests for your reference.
Environmental test project description:
Simulate various harsh environments and reliability assessments used by tablet computers to test whether their performance meets the requirements; It mainly includes high and low temperature operation and high and low temperature storage, temperature and condensation, temperature cycle and shock, wet and heat combination test, ultraviolet, sunlight, drip, dust, salt spray and other tests.
Operating temperature range: 0℃ ~ 35℃/5% ~ 95%RH
Storage temperature range: -10℃ ~ 50℃/10% ~ 90%RH
Operating low temperature test: -10℃/2h/ power operation
Operating high temperature test: 40℃/8h/ all running
Storage low temperature test: -20℃/96h/ shutdown
Storage high temperature test: 60℃/96h/ shutdown
High temperature test of vehicle storage: 85℃/96h/ shutdown
Temperature shock: -40℃(30min)←→80℃(30min)/10cycle
Wet heat test: 40℃/95%R.H./48h/ power standby
Hot and humid cycle test: 40℃/95%R.H./1h→ramp:1℃/min→-10℃/1h, 20cycles, power standby
Wet heat test: 40℃/95%R.H./48h/ power standby
Hot and humid cycle test: 40℃/95%R.H./1h→ramp:1℃/min→-10℃/1h, 20cycles, power standby
Weather resistance test:
Simulation of the most severe natural conditions, solar thermal effect test, each cycle of 24 hours, 8 hours of continuous exposure, 16 hours to keep dark, each cycle radiation amount of 8.96 kWh/m2, a total of 10cycles.
Salt spray test:
5% sodium chloride solution/Water temperature 35°C/PH 6.5~7.2/24h/ Shutdown → Pure water wipe shell →55°C/0.5h→ Function test: after 2 hours, after 40/80%R.H./168h.
Dripping test: According to IEC60529, in line with IPX2 waterproof rating, can prevent water droplets falling at an Angle of less than 15 degrees from entering the tablet computer and causing damage. Test conditions: water flow rate 3mm/min, 2.5min at each position, checkpoint: after test, 24 hours later, standby for 1 week.
Dust Test:
According to IEC60529, in line with the IP5X dust class, can not completely prevent the entry of dust but does not affect the device should be the action and anquan, in addition to tablet computers are currently many personal mobile portable 3C products commonly used dust standards, such as: mobile phones, digital cameras, MP3, MP4... Let's wait.
Conditions:
Dust sample 110mm/3 ~ 8h/ test for dynamic operation
After the test, a microscope is used to detect whether dust particles will enter the interior space of the tablet.
Chemical staining test:
Confirm the external components related to the tablet, confirm the chemical resistance of household chemicals, chemicals: sunscreen, lipstick, hand cream, mosquito repellent, cooking oil (salad oil, sunflower oil, olive oil... Etc.), the test time is 24 hours, check the color, gloss, surface smoothness... Etc., and confirm whether there are bubbles or cracks.
Mechanical test:
Test the strength of the mechanical structure of the tablet computer and the wear resistance of the key components; Mainly includes vibration test, drop test, impact test, plug test, and wear test... Etc.
Fall test: The height of 130cm, free fall on the smooth soil surface, each side fell 7 times, 2 sides a total of 14 times, tablet computer in standby state, each fall, the function of the test product is checked.
Repeated drop test: the height of 30cm, free drop on the smooth dense surface of 2cm thickness, each side fell 100 times, each interval of 2s, 7 sides a total of 700 times, every 20 times, check the function of the experimental product, tablet computer is in the state of power.
Random vibration test: frequency 30 ~ 100Hz, 2G, axial: three axial. Time: 1 hour in each direction, for a total of three hours, the tablet is in standby mode.
Screen impact resistance test: 11φ/5.5g copper ball fell on the center surface of 1m object at 1.8m height and 3ψ/9g stainless steel ball fell at 30cm height
Screen writing durability: more than 100,000 words (width R0.8mm, pressure 250g)
Screen touch durability: 1 million, 10 million, 160 million, 200 million times or more (width R8mm, hardness 60°, pressure 250g, 2 times per second)
Screen flat press test: the diameter of the rubber block is 8mm, the pressure speed is 1.2mm/min, the vertical direction is 5kg force flat press the window 3 times, each time for 5 seconds, the screen should display normally.
Screen front flat press test: The entire contact area, the direction of the vertical 25kg force front flat press each side of the tablet computer, for 10 seconds, flat press 3 times, there should be no abnormal.
Earphone plug and remove test: Insert the earphone vertically into the earphone hole, and then pull it out vertically. Repeat this for more than 5000 times
I/O plug and pull test: The tablet is in standby state, and the plug terminal connector is pulled out, a total of more than 5000 times
Pocket friction test: Simulate various materials pocket or backpack, the tablet is repeatedly rubbed in the pocket 2,000 times (friction test will also add some mixed dust particles, including dust particles, yan grass particles, fluff and paper particles for mixing test).
Screen hardness test: hardness greater than class 7 (ASTM D 3363, JIS 5400)
Screen impact test: hit the most vulnerable sides and center of the panel with a force of more than 5㎏
Temperature and Humidity Terms
Dew Point temperature Td, in the air water vapor content unchanged, maintain a certain pressure, so that the air cooling to reach saturation temperature called dew point temperature, referred to as dew point, the unit is expressed in ° C or ℉. It's actually the temperature at which water vapor and water are in equilibrium. The difference between the actual temperature (t) and the dew point temperature (Td) indicates how far the air is saturated. When t>Td, it means that the air is not saturated, when t=Td, it is saturated, and when t<Td, it is supersaturated.
dew is the liquid water in the air that condenses on the ground. In the evening or at night, due to the radiation cooling of the ground or ground objects, the air layer close to the surface will also cool down. When the temperature drops below the dew point, that is, when the water vapor content in the air is susaturated, there will be condensation of water vapor on the surface of the ground or ground objects. If the dew point temperature is above 0 ° C at this time, tiny water droplets appear on the ground or ground objects, which are called dew.
frost refers to the white ice crystals formed on the ground or objects after the air close to the ground is cooled to the frost point (meaning the dew point is below 0) under the influence of radiation cooling on the ground.
fog refers to the condensation of water vapor suspended in the atmosphere near the Earth's surface, composed of small water droplets or ice crystals. When the temperature reaches the dew point temperature (or is close to the dew point), the water vapor in the air condenses to form fog.
snow is solid water in the form of snowflakes that falls to the ground from mixed clouds. Precipitation consisting of a large number of white opaque ice crystals (snow crystals) and their polymers (snow masses). Snow is the natural phenomenon of water condensing and falling in the air, or falling snow;
There is a limit to the amount of water vapor that can be contained in a unit volume of air under a certain pressure and a certain temperature. If the water vapor contained in the volume of air exceeds this limit, the water vapor will condense and produce precipitation, and the actual value of water vapor in the volume of air. In terms of absolute humidity. The more water vapor there is, the higher the absolute humidity of the air.
Relative Humidity refers to the percentage of water vapor pressure in the air and saturated water vapor pressure at the same temperature, or the ratio of the absolute humidity of wet air to the maximum absolute humidity that can be reached at the same temperature, and can also be expressed as the ratio of the partial pressure of water vapor in wet air to the saturation pressure of water at the same temperature.
Humidity: wet and dry bulb measurement
The dry and wet bulb thermometer is used to detect the [relative humidity] in the air, the dry bulb temperature is the temperature measured by the general temperature sensor, and the wet bulb temperature is tied on the temperature sensor with a wet cloth, and then soaked in a small cup of water, so that the water is wrapped in the whole sensor, because the relative humidity in the air must be less than or equal to 100% (the water vapor in the air is not saturated). Therefore, the moisture of the wet bulb will be evaporated, and the heat will be taken away during evaporation, resulting in a drop in the wet bulb temperature (the dry bulb temperature is the real air temperature), which means that the greater the difference in the readings of the dry and wet bulb thermometer, the more vigorous the evaporation of water, and the smaller the relative humidity in the air, as long as the temperature of the dry and wet bulb is measured, Then compare [relative humidity table] you can know the relative humidity of the environment at that time.
Temperature Cyclic Stress Screening (1)
Environmental Stress Screening (ESS)
Stress screening is the use of acceleration techniques and environmental stress under the design strength limit, such as: burn in, temperature cycling, random vibration, power cycle... By accelerating the stress, the potential defects in the product emerge [potential parts material defects, design defects, process defects, process defects], and eliminate electronic or mechanical residual stress, as well as eliminate stray capacitors between multi-layer circuit boards, the early death stage of the product in the bath curve is removed and repaired in advance, so that the product through moderate screening, Save the normal period and decline period of the bathtub curve to avoid the product in the process of use, the test of environmental stress sometimes lead to failure, resulting in unnecessary losses. Although the use of ESS stress screening will increase the cost and time, for improving the product delivery yield and reduce the number of repairs, there is a significant effect, but for the total cost will be reduced. In addition, customer trust will also be improved, generally for electronic parts of the stress screening methods are pre-burning, temperature cycle, high temperature, low temperature, PCB printed circuit board stress screening method is temperature cycle, for the electronic cost of the stress screening is: Power pre-burning, temperature cycling, random vibration, in addition to the stress screen itself is a process stage, rather than a test, screening is 100% of the product procedure.
Stress screening applicable product stage: R & D stage, mass production stage, before delivery (screening test can be carried out in components, devices, connectors and other products or the whole machine system, according to different requirements can have different screening stress)
Stress screening comparison:
a. Constant high temperature pre-burning (Burn in) stress screening, is the current electronic IT industry commonly used method to precipitate electronic components defects, but this method is not suitable for screening parts (PCB, IC, resistor, capacitor), According to statistics, the number of companies in the United States that use temperature cycling to screen parts is five times more than the number of companies that use constant high temperature prefiring to screen components.
B. GJB/DZ34 indicates the proportion of temperature cycle and random vibrating screen selection defects, temperature accounted for about 80%, vibration accounted for about 20% of the defects in various products.
c. The United States has conducted a survey of 42 enterprises, random vibration stress can screen out 15 to 25% of the defects, while the temperature cycle can screen out 75 to 85%, if the combination of the two can reach 90%.
d. The proportion of product defect types detected by temperature cycling: insufficient design margin: 5%, production and workmanship errors: 33%, defective parts: 62%
Description of fault induction of temperature cyclic stress screening:
The cause of product failure induced by temperature cycling is: when the temperature is cycled within the upper and lower extremal temperatures, the product produces alternating expansion and contraction, resulting in thermal stress and strain in the product. If there is a transient thermal ladder (temperature non-uniformity) within the product, or the thermal expansion coefficients of adjacent materials within the product do not match each other, these thermal stresses and strains will be more drastic. This stress and strain is greatest at the defect, and this cycle causes the defect to grow so large that it can eventually cause structural failure and generate electrical failure. For example, a cracked electroplated through-hole eventually cracks completely around it, causing an open circuit. Thermal cycling enables soldering and plating through holes on printed circuit boards... Temperature cyclic stress screening is especially suitable for electronic products with printed circuit board structure.
The fault mode triggered by the temperature cycle or the impact on the product is as follows:
a. The expansion of various microscopic cracks in the coating, material or wire
b. Loosen poorly bonded joints
c. Loosen improperly connected or riveted joints
d. Relax the pressed fittings with insufficient mechanical tension
e. Increase the contact resistance of poor quality solder joints or cause an open circuit
f. Particle, chemical pollution
g. Seal failure
h. Packaging issues, such as bonding of protective coatings
i. Short circuit or open circuit of the transformer and coil
j. The potentiometer is defective
k. Poor connection of welding and welding points
l. Cold welding contact
m. Multi-layer board due to improper handling of open circuit, short circuit
n. Short circuit of power transistor
o. Capacitor, transistor bad
p. Dual row integrated circuit failure
q. A box or cable that is nearly short-circuited due to damage or improper assembly
r. Breakage, breakage, scoring of material due to improper handling... Etc.
s. out-of-tolerance parts and materials
t. resistor ruptured due to lack of synthetic rubber buffer coating
u. The transistor hair is involved in the grounding of the metal strip
v. Mica insulation gasket rupture, resulting in short circuit transistor
w. Improper fixing of the metal plate of the regulating coil leads to irregular output
x. The bipolar vacuum tube is open internally at low temperature
y. Coil indirect short circuit
z. Ungrounded terminals
a1. Component parameter drift
a2. Components are improperly installed
a3. Misused components
a4. Seal failure
Introduction of stress parameters for temperature cyclic stress screening:
The stress parameters of temperature cyclic stress screening mainly include the following: high and low temperature extremum range, dwell time, temperature variability, cycle number
High and low temperature extremal range: the larger the range of high and low temperature extremal, the fewer cycles required, the lower the cost, but can not exceed the product can withstand the limit, do not cause new fault principle, the difference between the upper and lower limits of temperature change is not less than 88°C, the typical range of change is -54°C to 55°C.
Dwell time: In addition, the dwell time can not be too short, otherwise it is too late to make the product under test produce thermal expansion and contraction stress changes, as for the dwell time, the dwell time of different products is different, you can refer to the relevant specification requirements.
Number of cycles: As for the number of cycles of temperature cyclic stress screening, it is also determined by considering product characteristics, complexity, upper and lower limits of temperature and screening rate, and the screening number should not be exceeded, otherwise it will cause unnecessary harm to the product and cannot improve the screening rate. The number of temperature cycles ranges from 1 to 10 cycles [ordinary screening, primary screening] to 20 to 60 cycles [precision screening, secondary screening], for the removal of the most likely workmanship defects, about 6 to 10 cycles can be effectively removed, in addition to the effectiveness of the temperature cycle, Mainly depends on the temperature variation of the product surface, rather than the temperature variation inside the test box.
There are seven main influencing parameters of temperature cycle:
(1) Temperature Range
(2) Number of Cycles
(3) Temperature Rate of Chang
(4) Dwell Time
(5) Airflow Velocities
(6) Uniformity of Stress
(7) Function test or not (Product Operating Condition)
IEC-60068-2 Combined Test of Condensation and Temperature and Humidity
Difference of IEC60068-2 damp heat test specifications
In the IEC60068-2 specification, there are a total of five kinds of humid heat tests, in addition to the common 85℃/85%R.H., 40℃/93%R.H. In addition to fixed-point high temperature and high humidity, there are two more special tests [IEC60068-2-30, IEC60068-2-38], these two are alternating wet and humid cycle and temperature and humidity combined cycle, so the test process will change temperature and humidity, and even multiple groups of program links and cycles, applied in IC semiconductors, parts, equipment, etc. To simulate the outdoor condensation phenomenon, evaluate the material's ability to prevent water and gas diffusion, and accelerate the product's tolerance to deterioration, the five specifications were organized into a comparison table of the differences in the wet and heat test specifications, and the test points were explained in detail for the wet and heat combined cycle test, and the test conditions and points of GJB in the wet and heat test were supplemented.
IEC60068-2-30 alternating humid heat cycle test
This test uses the test technique of maintaining humidity and temperature alternating to make moisture penetrate into the sample and cause condensation (condensation) on the surface of the product to be tested, so as to confirm the adaptability of the component, equipment or other products in use, transportation and storage under the combination of high humidity and temperature and humidity cyclic changes. This specification is also suitable for large test samples. If the equipment and the test process need to keep the power heating components for this test, the effect will be better than IEC60068-2-38, the high temperature used in this test has two (40 ° C, 55 ° C), the 40 ° C is to meet most of the world's high temperature environment, while 55 ° C meets all the world's high temperature environment, the test conditions are also divided into [cycle 1, cycle 2], In terms of severity, [Cycle 1] is higher than [Cycle 2].
Suitable for side products: components, equipment, various types of products to be tested
Test environment: the combination of high humidity and temperature cyclic changes produces condensation, and three kinds of environments can be tested [use, storage, transportation ([packaging is optional)]
Test stress: Breathing causes water vapor to invade
Whether power is available: Yes
Not suitable for: parts that are too light and too small
Test process and post-test inspection and observation: check the electrical changes after moisture [do not take out the intermediate inspection]
Test conditions: Humidity: 95%R.H.[Temperature change after high humidity maintenance](low temperature 25±3℃←→ high temperature 40℃ or 55℃)
Rising and cooling rate: heating (0.14℃/min), cooling (0.08 ~ 0.16℃/min)
Cycle 1: Where absorption and respiratory effects are important features, the test sample is more complex [humidity not less than 90%R.H.]
Cycle 2: In the case of less obvious absorption and respiratory effects, the test sample is simpler [humidity is not less than 80%R.H.]
IEC60068-2 damp heat test specification difference comparison table
For component type parts products, a combination test method is used to accelerate the confirmation of the test sample's resistance to degradation under high temperature, high humidity and low temperature conditions. This test method is different from the product defects caused by respiration [dew, moisture absorption] of IEC60068-2-30. The severity of this test is higher than that of other humid heat cycle tests, because there are more temperature changes and [respiration] during the test, the cycle temperature range is larger [from 55℃ to 65℃], and the temperature change rate of the temperature cycle is faster [temperature rise: 0.14 ° C /min becomes 0.38 ° C /min, 0.08 ° C /min becomes 1.16 ° C /min], in addition, different from the general humid heat cycle, the low temperature cycle condition of -10 ° C is added to accelerate the breathing rate and make the water condensed in the gap of the substitute freeze, which is the characteristic of this test specification. The test process allows the power test and the applied load power test, but it can not affect the test conditions (temperature and humidity fluctuation, rising and cooling rate) because of the heating of the side product after power. Due to the change of temperature and humidity during the test process, there can not be condensation water droplets on the top of the test chamber to the side product.
Suitable for side products: components, metal components sealing, lead end sealing
Test environment: combination of high temperature, high humidity and low temperature conditions
Test stress: accelerated breathing + frozen water
Whether it can be powered on: it can be powered on and external electric load (it can not affect the conditions of the test chamber because of power heating)
Not applicable: Can not replace moist heat and alternating humid heat, this test is used to produce defects different from respiration
Test process and post-test inspection and observation: check the electrical changes after moisture [check under high humidity conditions and take out after test]
Test conditions: damp heat cycle (25 please - 65 + 2 ℃ / 93 + / - 3% R.H.) please - low temperature cycle (25 please - 65 + 2 ℃ / 93 + 3% R.H. - - 10 + 2 ℃) X5cycle = 10 cycle
Rising and cooling rate: heating (0.38℃/min), cooling (1.16 ℃/min)
Heat and humidity cycle (25←→65±2℃/93±3%R.H.)
Low temperature cycle (25←→65±2℃/93±3%R.H. →-10±2℃)
GJB150-09 damp heat test
Instructions: The wet and heat test of GJB150-09 is to confirm the ability of equipment to withstand the influence of hot and humid atmosphere, suitable for equipment stored and used in hot and humid environments, equipment prone to high humidity, or equipment that may have potential problems related to heat and humidity. Hot and humid locations can occur throughout the year in the tropics, seasonally in mid-latitudes, and in equipment subjected to combined pressure, temperature and humidity changes, with special emphasis on 60 ° C /95%R.H. This high temperature and humidity does not occur in nature, nor does it simulate the dampness and heat effect after solar radiation, but it can find the parts of the equipment with potential problems, but it cannot reproduce the complex temperature and humidity environment, evaluate the long-term effect, and can not reproduce the humidity impact related to the low humidity environment.
Relevant equipment for condensation, wet freezing, wet heat combined cycle test: constant temperature and humidity test chamber
Temperature Cycling Test
Temperature Cycling, in order to simulate the temperature conditions encountered by different electronic components in the actual use environment, changing the ambient temperature difference range and rapid rise and fall temperature change can provide a more stringent test environment, but it must be noted that additional effects may be caused to material testing. For the relevant international standard test conditions of temperature cycle test, there are two ways to set the temperature change. Macroshow Technology provides an intuitive setting interface, which is convenient for users to set according to the specification. You can choose the total Ramp time or set the rise and cooling rate with the temperature change rate per minute.
List of international specifications for temperature cycling tests:
Total Ramp time (min) : JESD22-A104, MIL-STD-8831, CR200315
Temperature variation per minute (℃/min) : IEC 60749, IPC-9701, Bellcore-GR-468, MIL-2164
Example: Lead-free solder joint reliability test
Instructions: For the reliability test of lead-free solder joints, different test conditions will also be different in terms of the temperature change setting mode. For example, (JEDEC JESD22-A104) will specify the temperature change time with the total time [10min], while other conditions will specify the temperature change rate with [10℃/ min], such as from 100 ℃ to 0℃. With a temperature change of 10 degrees per minute, that is to say, the total temperature change time is 10 minutes.
100℃ [10min]←→0℃[10min], Ramp: 10℃/ min, 6500cycle
-40℃[5min]←→125℃ [5min], Ramp: 10min,
200cycle check once, 2000cycle tensile test [JEDEC JESD22-A104]
-40℃(15min)←→125℃(15min), Ramp: 15min, 2000cycle
Example: LED Automotive lighting (High Power LED)
The temperature cycle test condition of LED car lights is -40 ° C to 100 ° C for 30 minutes, the total temperature change time is 5 minutes, if converted into temperature change rate, it is 28 degrees per minute (28 ° C /min).
Test conditions: -40℃(30min)←→100℃(30min), Ramp: 5min
Equipo de prueba ambiental de confiabilidad combinado con aplicaciones de detección y control de temperatura de múltiples pistasEl equipo de prueba ambiental incluye una cámara de prueba de temperatura y humedad constante, una cámara de prueba de choque frío y caliente, una cámara de prueba de ciclo de temperatura, un horno sin viento... Todos estos equipos de prueba se encuentran en un entorno simulado de temperatura y humedad que impactan en el producto, para averiguarlo. El proceso de diseño, producción, almacenamiento, transporte y uso puede aparecer defectos del producto, anteriormente solo se simulaba la temperatura del aire del área de prueba, pero en los nuevos estándares internacionales y las nuevas condiciones de prueba de la fábrica internacional, el comienzo de los requisitos basados en la temperatura del aire. no lo es. Es la temperatura de la superficie del producto de prueba. Además, la temperatura de la superficie también debe medirse y registrarse sincrónicamente durante el proceso de prueba para el análisis posterior a la prueba. El equipo de prueba ambiental relevante debe combinarse con el control de la temperatura de la superficie y la aplicación de la medición de la temperatura de la superficie se resume a continuación. Aplicación de detección de temperatura de la mesa de prueba de la cámara de prueba de temperatura y humedad constantes: Descripción: Cámara de prueba de temperatura y humedad constantes en el proceso de prueba, combinada con detección de temperatura multipista, alta temperatura y humedad, condensación (condensación), temperatura y humedad combinadas, ciclo de temperatura lento... Durante el proceso de prueba, el sensor fijado a la superficie del producto de prueba, que se puede utilizar para medir la temperatura de la superficie o la temperatura interna del producto de prueba. A través de este módulo de detección de temperatura de múltiples pistas, las condiciones establecidas, la temperatura y humedad reales, la temperatura de la superficie del producto de prueba y la misma medición y registro se pueden integrar en un archivo de curva sincrónico para su posterior almacenamiento y análisis.Aplicaciones de detección y control de temperatura de la superficie de la cámara de prueba de choque térmico: [tiempo de permanencia basado en el control de la temperatura de la superficie], [registro de medición de la temperatura de la superficie del proceso de choque de temperatura] Descripción: El sensor de temperatura de 8 rieles se fija a la superficie del producto de prueba y se aplica al proceso de choque de temperatura. El tiempo de permanencia se puede contar hacia atrás según la llegada de la temperatura superficial. Durante el proceso de impacto, las condiciones de fraguado, la temperatura de prueba, la temperatura de la superficie del producto de prueba y la misma medición y registro se pueden integrar en una curva sincrónica.Aplicación de detección y control de temperatura de la superficie de la cámara de prueba del ciclo de temperatura: [La variabilidad de la temperatura del ciclo de temperatura y el tiempo de permanencia se controlan de acuerdo con la temperatura de la superficie del producto de prueba] Descripción: La prueba del ciclo de temperatura es diferente de la prueba de choque de temperatura. La prueba de choque de temperatura utiliza la energía máxima del sistema para realizar cambios de temperatura entre temperaturas altas y bajas, y su tasa de cambio de temperatura es tan alta como 30 ~ 40 ℃ /min. La prueba del ciclo de temperatura requiere un proceso de cambios de temperatura alta y baja, y su variabilidad de temperatura se puede configurar y controlar. Sin embargo, las nuevas especificaciones y las condiciones de prueba de los fabricantes internacionales han comenzado a exigir que la variabilidad de la temperatura se refiera a la temperatura de la superficie del producto de prueba, no a la temperatura del aire, y el control de variabilidad de la temperatura de la especificación del ciclo de temperatura actual. Según las especificaciones de la superficie del producto de prueba son [JEDEC-22A-104F, IEC60749-25, IPC9701, ISO16750, AEC-Q100, LV124, GMW3172]... Además, el tiempo de residencia de temperaturas altas y bajas también puede basarse en la superficie de prueba, en lugar de la temperatura del aire.Aplicaciones de detección y control de temperatura de la superficie de la cámara de prueba de detección de estrés cíclico de temperatura: Instrucciones: Máquina de prueba de detección de tensión por ciclo de temperatura, combinada con medición de temperatura de múltiples rieles, en la variabilidad de temperatura de la detección de tensión, puede optar por usar [temperatura del aire] o [temperatura de la superficie del producto de prueba] para controlar la variabilidad de la temperatura, además, En el proceso residente de alta y baja temperatura, el tiempo recíproco también se puede controlar según la superficie del producto de prueba. De acuerdo con las especificaciones pertinentes (GJB1032, IEST) y los requisitos de las organizaciones internacionales, de acuerdo con la definición de GJB1032 en el punto de medición de temperatura y tiempo de residencia de detección de tensión, 1. El número de termopares fijados en el producto no será inferior a 3, y el punto de medición de temperatura del sistema de enfriamiento no deberá ser inferior a 6, 2. Asegúrese de que la temperatura de 2/3 de los termopares del producto esté establecida en ±10 ℃, además, de acuerdo con los requisitos de IEST (Internacional Association for Environmental Science and Technology), el tiempo de residencia debe alcanzar el tiempo de estabilización de temperatura más 5 minutos o el tiempo de prueba de rendimiento. Aplicación de detección de temperatura de superficie sin horno de aire (cámara de prueba de convección natural): Descripción: Mediante la combinación de un horno sin viento (cámara de prueba de convección natural) y un módulo de detección de temperatura multipista, se genera la temperatura ambiente sin ventilador (convección natural) y se integra la prueba de detección de temperatura relevante. Esta solución se puede aplicar a la prueba de temperatura ambiente real de productos electrónicos (como: servidor en la nube, 5G, interior de vehículos eléctricos, ambiente interior sin aire acondicionado, inversor solar, televisor LCD grande, compartidor de Internet en el hogar, oficina 3C, computadora portátil, computadora de escritorio). , consola de juegos....... Etc.).
Propósito de la prueba de choque de temperaturaPrueba ambiental de confiabilidad Además de las altas temperaturas, bajas temperaturas, altas temperaturas y alta humedad, ciclo combinado de temperatura y humedad, el choque de temperatura (choque de frío y calor) también es un proyecto de prueba común, pruebas de choque de temperatura (pruebas de choque térmico, pruebas de choque de temperatura , denominado: TST), el propósito de la prueba de choque de temperatura es descubrir los defectos de diseño y proceso del producto a través de cambios severos de temperatura que exceden el ambiente natural [variabilidad de temperatura superior a 20 ℃ / min, e incluso hasta a 30 ~ 40 ℃/min], pero a menudo hay una situación en la que el ciclo de temperatura se confunde con el choque de temperatura. "Ciclo de temperatura" significa que en el proceso de cambio de temperatura alta y baja, se especifica y controla la tasa de cambio de temperatura; La tasa de cambio de temperatura del "choque de temperatura" (choque de frío y calor) no está especificada (tiempo de rampa), requiere principalmente tiempo de recuperación; de acuerdo con la especificación IEC, existen tres tipos de métodos de prueba de ciclo de temperatura [Na, Nb, NC] . El choque térmico es uno de los tres elementos de la prueba [Na] [cambio rápido de temperatura con un tiempo de conversión específico; medio: aire], los principales parámetros del choque de temperatura (choque térmico) son: Condiciones de alta y baja temperatura, tiempo de residencia, tiempo de retorno, número de ciclos, en condiciones de alta y baja temperatura y tiempo de residencia se basará la nueva especificación actual de la temperatura de la superficie del producto de prueba, en lugar de la temperatura del aire en el área de prueba del equipo de prueba.Cámara de prueba de choque térmico:Se utiliza para probar la estructura del material o el material compuesto, en un instante bajo un ambiente continuo de temperatura extremadamente alta y temperatura extremadamente baja, el grado de tolerancia, para probar los cambios químicos o daños físicos causados por la expansión y contracción térmica en En el menor tiempo, los objetos aplicables incluyen metal, plástico, caucho, electrónica... Dichos materiales pueden utilizarse como base o referencia para la mejora de sus productos.El proceso de prueba de frío y choque térmico (choque de temperatura) puede identificar los siguientes defectos del producto:Diferente coeficiente de dilatación provocado por el decapado de la junta.El agua entra después del agrietamiento con diferente coeficiente de expansión.Prueba acelerada de corrosión y cortocircuito por infiltración de agua.Según la norma internacional IEC, las siguientes condiciones son cambios de temperatura comunes:1. Cuando el equipo se transfiere de un ambiente interior cálido a un ambiente exterior frío, o viceversa2. Cuando el equipo se enfría repentinamente por lluvia o agua fría3. Instalado en el equipo aerotransportado exterior (como: automóvil, 5G, sistema de monitoreo exterior, energía solar)4. En determinadas condiciones de transporte [automóvil, barco, aire] y almacenamiento [almacén sin aire acondicionado]El impacto de la temperatura se puede dividir en dos tipos: impacto de dos cajas e impacto de tres cajas:Instrucciones: El impacto de la temperatura es común [alta temperatura → baja temperatura, baja temperatura → alta temperatura], esta forma también se llama [impacto de dos cajas], otro llamado [impacto de tres cajas], el proceso es [alta temperatura → temperatura normal → baja temperatura, baja temperatura → temperatura normal → temperatura alta], insertado entre la temperatura alta y la temperatura baja, para evitar agregar un amortiguador entre las dos temperaturas extremas. Si observa las especificaciones y las condiciones de prueba, generalmente hay una condición de temperatura normal, la temperatura alta y baja será extremadamente alta y muy baja, en las especificaciones militares y las regulaciones del vehículo verá que hay una condición de impacto de temperatura normal.Condiciones de prueba de choque de temperatura IEC:Alta temperatura: 30, 40, 55, 70, 85, 100, 125, 155 ℃Baja temperatura: 5, -5, -10, -25, -40, -55, -65 ℃Tiempo de residencia: 10 min, 30 min, 1 h, 2 h, 3 h (si no se especifica, 3 h)Descripción del tiempo de residencia del choque de temperatura:El tiempo de permanencia del choque de temperatura, además de los requisitos de la especificación, dependerá del peso del producto de prueba y de la temperatura de la superficie del producto de prueba.Las especificaciones del tiempo de residencia del choque térmico según peso son:GJB360A-96-107, MIL-202F-107, EIAJ ED4701/100, JASO-D001... Esperemos.El tiempo de residencia del choque térmico se basa en las especificaciones de control de temperatura de la superficie: MIL-STD-883K, MIL-STD-202H (aire sobre el objeto de prueba)Requisitos MIL883K-2016 para la especificación [choque de temperatura]:1. Después de que la temperatura del aire alcance el valor establecido, la superficie del producto de prueba debe llegar en 16 minutos (el tiempo de residencia no es inferior a 10 minutos).2. El impacto de las altas y bajas temperaturas supera el valor establecido, pero no supera los 10 ℃.Medidas de seguimiento de la prueba de choque térmico IECMotivo: Es mejor considerar el método de prueba de temperatura IEC como parte de una serie de pruebas, porque algunas fallas pueden no ser evidentes inmediatamente después de completar el método de prueba.Elementos de prueba de seguimiento:Prueba de estanqueidad IEC60068-2-17IEC60068-2-6 Vibración sinusoidalIEC60068-2-78 Calor húmedo constanteIEC60068-2-30 Ciclo de temperatura caliente y húmedaAcabado de condiciones de prueba de impacto de temperatura de bigote de estaño:1. - 55 (+ 0 / -) 10 ℃ por favor - 85 (+ / - 0) 10 ℃, 20 min / 1 ciclo (500 ciclos verifique nuevamente)1000 ciclos, 1500 ciclos, 2000 ciclos, 3000 ciclos2. 85(±5)℃←→-40(+5/-15)℃, 20min/1ciclo, 500ciclos3.-35±5℃←→125±5℃, permanecer durante 7 minutos, 500±4ciclos4. - 55 (+ 0 / -) 10 ℃ por favor - 80 (+ / - 0) 10 ℃, 7 min en residencia, 20 min / 1 ciclo, 1000 ciclosCaracterísticas del producto de la máquina de prueba de choque térmico:Frecuencia de descongelación: descongelación cada 600 ciclos [Condición de prueba: +150 ℃ ~ -55 ℃]Función de ajuste de carga: el sistema puede ajustarse automáticamente según la carga del producto a probar, sin configuración manualCarga de peso elevado: antes de que el equipo salga de fábrica, utilice IC de aluminio (7,5 kg) para la simulación de carga para confirmar que el equipo puede satisfacer la demanda.Ubicación del sensor de choque de temperatura: Se puede seleccionar la salida de aire y la salida de aire de retorno en el área de prueba o se pueden instalar ambas, lo que cumple con la especificación de prueba MIL-STD. Además de cumplir con los requisitos de la especificación, también se acerca más al efecto de impacto del producto de prueba durante la prueba, lo que reduce la incertidumbre de la prueba y la uniformidad de la distribución.
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