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
Équipement de test environnemental de fiabilité combiné à des applications de contrôle et de détection de température multi-pistesL'équipement de test environnemental comprend une chambre d'essai à température et humidité constantes, une chambre d'essai de choc chaud et froid, une chambre d'essai de cycle de température, pas de four à vent... Ces équipements de test sont tous dans l'environnement simulé de la température, de l'impact de l'humidité sur le produit, pour le savoir. la conception, la production, le stockage, le transport et le processus d'utilisation peuvent apparaître des défauts du produit, auparavant seulement la température de l'air de la zone de test simulée, mais dans les nouvelles normes internationales et les nouvelles conditions de test de l'usine internationale, le début des exigences basées sur la température de l'air ne l'est pas. C'est la température de surface du produit testé. De plus, la température de surface doit également être mesurée et enregistrée de manière synchrone pendant le processus de test pour une analyse post-test. L'équipement d'essai environnemental pertinent doit être combiné avec le contrôle de la température de surface et l'application de la mesure de la température de surface est résumée comme suit. Application de détection de température de table d'essai de chambre d'essai de température et d'humidité constantes : Description : Chambre de test de température et d'humidité constantes dans le processus de test, combinée à une détection de température multipiste, une température et une humidité élevées, une condensation (condensation), une température et une humidité combinées, un cycle de température lent... Pendant le processus de test, le capteur est apposé sur la surface du produit testé, qui peut être utilisé pour mesurer la température de surface ou la température interne du produit testé. Grâce à ce module de détection de température multipiste, les conditions définies, la température et l'humidité réelles, la température de surface du produit testé, ainsi que les mêmes mesures et enregistrements peuvent être intégrés dans un fichier de courbe synchrone pour un stockage et une analyse ultérieurs.Applications de contrôle et de détection de la température de surface de la chambre d'essai de choc thermique : [temps de séjour basé sur le contrôle de la température de surface], [enregistrement de mesure de la température de surface du processus de choc thermique] Description : Le capteur de température à 8 rails est fixé à la surface du produit testé et appliqué au processus de choc thermique. Le temps de séjour peut être décompté en fonction de l'arrivée de la température de surface. Pendant le processus d'impact, les conditions de prise, la température de test, la température de surface du produit de test, ainsi que les mêmes mesures et enregistrements peuvent être intégrés dans une courbe synchrone.Application de contrôle et de détection de la température de surface de la chambre d'essai de cycle de température : [La variabilité de la température du cycle de température et le temps de séjour sont contrôlés en fonction de la température de surface du produit testé] Description : Le test de cycle de température est différent du test de choc thermique. Le test de choc thermique utilise l'énergie maximale du système pour effectuer des changements de température entre des températures élevées et basses, et son taux de changement de température peut atteindre 30 ~ 40 ℃/min. Le test du cycle de température nécessite un processus de changements de température élevés et faibles, et sa variabilité de température peut être réglée et contrôlée. Cependant, les nouvelles spécifications et les conditions de test des fabricants internationaux ont commencé à exiger que la variabilité de la température se réfère à la température de surface du produit testé, et non à la température de l'air, et au contrôle actuel de la variabilité de la température des spécifications du cycle de température. Selon les spécifications de surface du produit testé sont [JEDEC-22A-104F, IEC60749-25, IPC9701, ISO16750, AEC-Q100, LV124, GMW3172]... De plus, le temps de séjour des températures élevées et basses peut également être basé sur la surface d’essai, plutôt que la température de l’air.Applications de contrôle et de détection de la température de surface de la chambre d'essai de dépistage des contraintes cycliques en température : Instructions : Machine d'essai de dépistage des contraintes du cycle de température, combinée à une mesure de température multi-rails, dans la variabilité de la température du dépistage des contraintes, vous pouvez choisir d'utiliser [température de l'air] ou [température de la surface du produit testé] pour contrôler la variabilité de la température, en plus, dans le processus résident à haute et basse température, le temps réciproque peut également être contrôlé en fonction de la surface du produit testé. Conformément aux spécifications pertinentes (GJB1032, IEST) et aux exigences des organisations internationales, selon la définition de GJB1032 dans le temps de séjour et le point de mesure de la température de dépistage des contraintes, 1. Le nombre de thermocouples fixés sur le produit ne doit pas être inférieur à 3, et le point de mesure de la température du système de refroidissement ne doit pas être inférieur à 6, 2. Assurez-vous que la température des 2/3 des thermocouples sur le produit est réglée à ± 10 ℃, en outre, conformément aux exigences de l'IEST (International Association for Environmental Science and Technology), le temps de séjour doit atteindre le temps de stabilisation de la température plus 5 minutes ou le temps de test de performance. Application de détection de température de surface sans four à air (chambre d'essai à convection naturelle) : Description : Grâce à la combinaison d'un four sans vent (chambre d'essai à convection naturelle) et d'un module de détection de température multipiste, l'environnement de température sans ventilateur (convection naturelle) est généré et le test de détection de température pertinent est intégré. Cette solution peut être appliquée au test de température ambiante réelle des produits électroniques (tels que : serveur Cloud, 5G, intérieur de véhicule électrique, intérieur sans environnement de climatisation, onduleur solaire, grand téléviseur LCD, partage Internet domestique, bureau 3C, ordinateur portable, ordinateur de bureau. , console de jeux....... Etc.).
Objectif du test de choc thermiqueTest environnemental de fiabilité En plus des cycles combinés haute température, basse température, haute température et humidité élevée, température et humidité, le choc thermique (choc froid et chaud) est également un projet de test courant, les tests de choc thermique (test de choc thermique, test de choc thermique , appelé : TST), le but du test de choc thermique est de découvrir les défauts de conception et de processus du produit à travers les changements de température sévères qui dépassent l'environnement naturel [variabilité de la température supérieure à 20 ℃/min, et même jusqu'à à 30 ~ 40℃/min], mais il arrive souvent que le cycle de température soit confondu avec le choc thermique. « Cycle de température » signifie que dans le processus de changement de température haute et basse, le taux de changement de température est spécifié et contrôlé ; Le taux de changement de température du « choc thermique » (choc chaud et froid) n'est pas spécifié (temps de rampe), nécessite principalement un temps de récupération, selon la spécification CEI, il existe trois types de méthodes de test de cycle de température [Na, Nb, NC] . Le choc thermique est l'un des trois éléments de test [Na] [changement rapide de température avec un temps de conversion spécifié ; milieu : air], les principaux paramètres du choc thermique (choc thermique) sont : les conditions de température élevée et basse, le temps de séjour, le temps de retour, le nombre de cycles, dans des conditions de température élevée et basse et le temps de séjour, la nouvelle spécification actuelle sera basée sur la température de surface du produit testé, plutôt que sur la température de l'air dans la zone de test de l'équipement de test.Chambre d'essai de choc thermique :Il est utilisé pour tester la structure du matériau ou du matériau composite, en un instant dans un environnement continu de température extrêmement élevée et extrêmement basse, le degré de tolérance, de manière à tester les changements chimiques ou les dommages physiques causés par la dilatation et la contraction thermiques. dans les plus brefs délais, les objets applicables incluent le métal, le plastique, le caoutchouc, l'électronique.... Ces matériaux peuvent être utilisés comme base ou référence pour l'amélioration de ses produits.Le processus de test de choc froid et thermique (choc thermique) peut identifier les défauts de produit suivants :Coefficient de dilatation différent causé par le dénudage du jointL'eau entre après fissuration avec un coefficient de dilatation différentTest accéléré de corrosion et de court-circuit provoqués par une infiltration d'eauSelon la norme internationale CEI, les conditions suivantes sont des changements de température courants :1. Lorsque l'équipement est transféré d'un environnement intérieur chaud à un environnement extérieur froid, ou vice versa2. Lorsque l'équipement est soudainement refroidi par la pluie ou l'eau froide3. Installé dans les équipements aéroportés extérieurs (tels que : automobile, 5G, système de surveillance extérieur, énergie solaire)4. Sous certaines conditions de transport [voiture, bateau, air] et de stockage [entrepôt non climatisé]L’impact de la température peut être divisé en deux types d’impact à deux cases et d’impact à trois cases :Instructions : L'impact de la température est une méthode courante [haute température → basse température, basse température → haute température], cette méthode est également appelée [impact à deux boîtes], une autre soi-disant [impact à trois boîtes], le processus est [haute température → température normale → basse température, basse température → température normale → haute température], inséré entre la haute température et la basse température, pour éviter d'ajouter un tampon entre les deux températures extrêmes. Si vous regardez les spécifications et les conditions de test, il existe généralement une condition de température normale, les températures hautes et basses seront extrêmement élevées et très basses, dans les spécifications militaires et les réglementations sur les véhicules, vous verrez qu'il existe une condition d'impact de température normale.Conditions d’essai de choc thermique CEI :Haute température : 30, 40, 55, 70, 85, 100, 125, 155℃Basse température : 5, -5, -10, -25, -40, -55, -65℃Temps de séjour : 10min, 30min, 1h, 2h, 3h (si non précisé, 3h)Description du temps de séjour du choc thermique :Le temps de séjour du choc thermique, en plus des exigences de la spécification, dépendra en partie du poids du produit testé et de la température de surface du produit testé.Les spécifications du temps de séjour du choc thermique en fonction du poids sont :GJB360A-96-107, MIL-202F-107, EIAJ ED4701/100, JASO-D001... Attendons.Le temps de séjour du choc thermique est basé sur les spécifications de contrôle de la température de surface : MIL-STD-883K, MIL-STD-202H (air au-dessus de l'objet à tester)Exigences MIL883K-2016 pour la spécification [choc thermique] :1. Une fois que la température de l'air atteint la valeur définie, la surface du produit testé doit arriver dans les 16 minutes (le temps de séjour n'est pas inférieur à 10 minutes).2. Les impacts à haute et basse température sont supérieurs à la valeur définie, mais pas plus de 10 ℃.Action de suivi du test de choc thermique CEIRaison : Il est préférable de considérer la méthode d'essai de température CEI dans le cadre d'une série d'essais, car certaines défaillances peuvent ne pas être immédiatement apparentes une fois la méthode d'essai terminée.Éléments de test de suivi :Test d'étanchéité IEC60068-2-17Vibration sinusoïdale IEC60068-2-6Chaleur humide constante IEC60068-2-78IEC60068-2-30 Cycle de température chaude et humideConditions de test d'impact en température des moustaches d'étain (moustaches) finition :1. - 55 (+ 0 / -) 10 ℃ s'il vous plaît - 85 (+ / - 0) 10 ℃, 20 min / 1 cycle (vérifiez à nouveau le cycle 500)1 000 cycles, 1 500 cycles, 2 000 cycles, 3 000 cycles2. 85(±5)℃←→-40(+5/-15)℃, 20 min/1 cycle, 500 cycles3.-35 ± 5 ℃ ← → 125 ± 5 ℃, rester pendant 7 min, 500 ± 4 cycles4. - 55 (+ 0 / -) 10 ℃ s'il vous plaît - 80 (+ / - 0) 10 ℃, 7 min de résidence, 20 min / 1 cycle, 1000 cyclesCaractéristiques du produit de la machine d'essai de choc thermique :Fréquence de dégivrage : dégivrage tous les 600 cycles [Condition de test : +150 ℃ ~ -55 ℃]Fonction de réglage de la charge : Le système peut s'ajuster automatiquement en fonction de la charge du produit à tester, sans réglage manuelCharge de poids élevée : avant que l'équipement ne quitte l'usine, utilisez un circuit intégré en aluminium (7,5 kg) pour la simulation de charge afin de confirmer que l'équipement peut répondre à la demande.Emplacement du capteur de choc thermique : La sortie d'air et la sortie d'air de retour dans la zone de test peuvent être sélectionnées ou les deux peuvent être installées, ce qui est conforme aux spécifications de test MIL-STD. En plus de répondre aux exigences de la spécification, il est également plus proche de l'effet d'impact du produit testé pendant le test, réduisant ainsi l'incertitude du test et l'uniformité de la distribution.
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