Medical devices are highly specialized products, unlike other consumer electronics. They require extremely rigorous inspection and testing to ensure their reliability and stability. Here, DOTAUS Design has compiled and shared some reliability testing items for mutual learning and exchange.
Component environmental reliability testing
High temperature test
High temperatures have many effects on products, such as aging, oxidation, chemical changes, thermal diffusion, electromigration, metal migration, melting, vaporization, and deformation. Generally, for every 10°C increase in ambient temperature, the product lifespan is reduced by one-quarter; when the ambient temperature rises by 20°C, the product lifespan is reduced by half. Product lifespan follows the "10°C rule." Therefore, high-temperature testing is the most commonly used test for screening components and complete machines, aging tests, life tests, and accelerated life tests. It also plays an important role in the verification of failure analysis.
Test range: <200℃
Test parameters: less than 1m³ to 16m³
High temperature test Low temperature test
Low temperatures have many effects on products, such as embrittlement, freezing, increased viscosity, curing, reduced mechanical strength, and physical shrinkage. Low temperature tests are used to assess the adaptability of products to storage and use in low temperature environments. They are often used for type testing of products during the development stage and screening tests of components.
Test range: 0℃~-70℃
Test parameters: less than 1m³, 1m³, 18.9m³
Test range: -40℃ to -70℃
Test parameters: None required
Alternating damp heat test
Alternating heat and humidity tests simulate the environment of a tropical rainforest to determine the suitability of products and materials for use and storage under temperature changes and condensation on product surfaces. They are commonly used in life testing, evaluation testing, and comprehensive testing.
Test range: Temperature: -70℃~180℃
Humidity: 5%~98%
Test parameters: less than 1m³, 1m³, 18.9m³
Humidity < 20% (only C340 boxes can be used, low temperature ≥ -40℃)
Constant temperature and humidity test
Humidity accounts for over 40% of product failures, making humidity testing essential in environmental testing. It is commonly used in life testing, evaluation testing, and comprehensive testing, and plays a crucial role in failure analysis. This test is particularly necessary for products containing resin materials during product development and quality assessment. The commonly used "double 85" test refers to a temperature of 85℃ and a humidity of 85%RH.
Temperature/humidity environment, temperature dwell time
Test range: Temperature: -70℃~180℃
Humidity: 5%~98%
Test parameters: less than 1m³, 1m³, 18.9m³
Humidity <20%
thermal shock test
The purpose of temperature shock testing is to identify changes in product characteristics and malfunctions caused by the different coefficients of thermal expansion of dissimilar materials used in component manufacturing within a short period of time. These changes can be observed by rapidly and alternately exposing components to ultra-high and ultra-low temperature test environments. Thermal shock differs from environmental simulation testing; it uses temperature shock to uncover potential faults that are difficult to detect at room temperature.
Test range: Temperature: -75~220℃
Conversion time < 10 seconds
Test parameters: 770*650*610mm
Rapid temperature change test
Rapid temperature change is a temperature change with a specified rate of temperature change. It often simulates environments with large day-night temperature differences and can also be used for life testing to evaluate the appearance, mechanical properties, and electrical properties of components or products.
Test range: Temperature: -70℃~150℃
Test parameters: Temperature change rate ≤10℃/minute
Temperature change rate: 10~25℃/minute
Low pressure test
Low-pressure test chambers are mainly used in aviation, aerospace, information, electronics and other fields to determine the environmental adaptability and reliability of instruments, electrical products, materials, components and equipment under single or simultaneous low pressure, high temperature and low temperature.
Test range: Pressure: Atmospheric pressure ~ 10 kPa
Temperature: Room temperature ~ 200℃
Test parameters: 1 cubic meter
Ozone test
Ozone testing is applicable to testing the ozone aging resistance and aging cracking performance of rubber products, non-metallic materials, and organic materials (such as coatings, paints, rubber, plastics, and their products).
Test range: Concentration: 0~500 pphm
Temperature: Room temperature ~ 50℃
Test parameters: 550*500*700mm
High-pressure cooking (HAST)
The high-pressure boiling test uses high-pressure and high-humidity conditions to assess the comprehensive impact on electronic devices such as plastic-encapsulated semiconductor integrated circuits. It is a high-acceleration test method to evaluate the ability of electronic products to withstand damp heat and is often used in product development, quality assessment, and failure verification.
Test range: Temperature: 105~142.9℃
Humidity: 75%~100%
Pressure: 0.02~0.186Mpa
Test parameters: 400*280*270mm
Dustproof and waterproof test / IP rating
Dust and water resistance tests/IP ratings are mainly for electronic products and equipment used outdoors or in harsh environments. They are represented as IPXX. The first characteristic digit indicates the level of protection against approaching dangerous parts and the ingress of solid foreign objects, while the second characteristic digit indicates the level of protection against water ingress.
Test range: IPXX
Test parameters: Dustproof: 1~4X
Dustproof: 5~6X
Waterproof: X1~7
UV aging test
Used to simulate the destructive effects of sunlight, humidity, and temperature on materials; material aging includes fading, loss of gloss, reduced strength, cracking, peeling, powdering, and oxidation.
Test range: UVA340/UVB313/UVA351
Test parameters: Single sample size is 6*9cm
Xenon lamp aging/solar radiation
Using xenon arc lamps that simulate the full solar spectrum to reproduce destructive light waves present in different environments can provide corresponding environmental simulation and accelerated testing for scientific research, product development, and quality control.
Test range: Blackboard temperature range is 25℃~90℃
Test parameters: XE-3-HSC
Gas corrosion test
Gas corrosion testing is mainly applied to contact points and connectors. The evaluation criteria after the test are changes in contact resistance, followed by changes in appearance. The main corrosive gases are sulfur dioxide, hydrogen sulfide, nitrogen dioxide, and chlorine. One or more gases can be selected for testing depending on the operating environment.
Test range: SO2/H2S/NO2/Cl2 concentration: 0.01~100ppm; Temperature: 0℃~90℃; Humidity: 10%~98%
Test parameters: 870*735*520mm
Salt spray test
Salt spray testing simulates the climate of a marine or humid region and is used to assess the resistance of products, materials, and their protective coatings to salt spray corrosion. There are two types of tests: salt spray testing and alternating salt spray testing. It is commonly used for quality assessment and failure verification under special conditions.
Test scope: NSS, AASS, CASS
Test parameters: 900*600mm
Test parameters: 1m³
Test Scope: NSS
Test parameters: 2400*1500mm
Flame retardancy test
Flame retardancy of materials refers to their ability to burn with a flame under specified test conditions. It includes characteristics such as ease of ignition and the ability to sustain combustion. Over the years, flame retardancy testing has developed into several standards, becoming a crucial testing item in related industries. 1. GB/T2408-2008 Determination of the flammability of plastics—Horizontal and vertical methods; 2. GB/T5169.16-2008 Fire hazard testing of electrical and electronic products—Part 16: Test flame 50W—Horizontal and vertical flame test methods; 3. GB4943.1-2011 Information technology equipment.
1. Gas used: 99.99% pure methane
2. Power: 50W (20mm nozzle), 500W (125mm nozzle)
3. Flame height adjustment: Adjustable from 20mm to 125mm according to standard requirements.
4. Internal volume ≥ 0.8 m³
5. Blowtorch angles: 20°, 45°, 90°
6. Time setting: Flame application time/afterflame time/afterglow time: 0～99min99s can be set, with a time accuracy of ≤0.1s.
Electrical reliability testing
Breakdown voltage
Under specified test conditions, the voltage at which the sample breaks down is expressed in kV.
Reference standards:
ASTM D149-09(2013)
GB/T1408.1-2006
IEC60243-1-2013
ASTMD1000-10
GB/T4677-2002
Dielectric strength
Under specified test conditions, the breakdown voltage is the quotient of the distance between the two electrodes (i.e., the sample thickness) to which the applied voltage is applied. Unit: kV/mm
Reference standards:
ASTM D149-09(2013)
GB/T1408.1-2006
IEC60243-1-2013
ASTMD1000-10
GB/T4677-2002
Dielectric constant
When the space between and around the electrodes of a capacitor is completely filled with insulating material, the ratio of its capacitance Cx to the vacuum capacitance C0 formed by the same electrodes is εr = Cx/C0.
Reference standards:
GB/T1409-2006
GB/T1693-2007
ASTM D150-11
Dielectric loss
The complementary angle between the phase difference between the voltage applied to a capacitor using insulating material as the dielectric and the current generated therefrom is called the dielectric loss angle, and its tangent is the dielectric loss factor.
Reference standards:
GB/T1409-2006
GB/T1693-2007
ASTMD150-11
Volume resistivity
The volume resistivity is the quotient of the prevailing electric field strength and the steady-state current density within an insulating material; its unit is Ω·cm or Ω·m.
Reference standards:
GB/T3048.3-2007
GB/T1410-2006
GB/T15662-1995
ASTM D257-14
Surface resistivity
The surface resistance of an insulating material is the ratio of the DC electric field strength to the linear current density within its surface layer; the unit is Ω/sq.
Reference standards:
GB/T3048.3-2007
GB/T1410-2006
GB/T15662-1995
ASTM D257-14
Withstand voltage
Withstand voltage is a test that measures the ability of insulation to withstand working voltage or overvoltage and to check the manufacturing or maintenance quality of electrical equipment insulation. It requires the use of a withstand voltage tester.
A withstand voltage test is an instrument used to measure withstand voltage strength. It can intuitively, accurately, quickly, and reliably test the withstand voltage, breakdown voltage, leakage current, and other electrical safety performance indicators of various tested objects. Its main purposes are: a. To test the ability of insulation to withstand working voltage or overvoltage. b. To inspect the manufacturing or maintenance quality of electrical equipment insulation. c. To eliminate damage to insulation caused by raw materials, processing, or transportation, reducing the early failure rate of products. d. To inspect the electrical clearances and creepage distances of insulation.
Reference standards:
EIA-364-20C
Equipment parameters:
Agilent/34420A
Contact resistance
Contact resistance is the resistance that exists between conductors.
Generally, contact resistance is required to be below 10-20 mohm. Some switches require it to be below 100-500 uohm. Some circuits are very sensitive to changes in contact resistance. It should be noted that the contact resistance of a switch is the maximum allowable contact resistance over a number of contacts.
On a circuit board, this specifically refers to the resistance at the contact point between the gold fingers and the connector, where current flows. To reduce the formation of oxides on the metal surface, the positive gold fingers and the female clips of the connector are usually plated with metal to suppress the occurrence of "contact resistance." Contact resistance also exists between the plugs of other electrical appliances and their sockets, or between the pins and the socket.
Reference standards:
EIA-364-06C
Equipment parameters:
Agilent/34420A
Insulation resistance
Modern life is changing rapidly, and people cannot live without electricity. However, electrical safety issues arise during electricity use, particularly with electrical equipment such as motors, cables, and household appliances.
DC resistance of an insulator under specified conditions.
Insulation resistance is the most basic insulation indicator for electrical equipment and wiring. For acceptance testing of low-voltage electrical installations, the insulation resistance of motors, distribution equipment, and distribution lines at room temperature should not be less than 0.5 MΩ (for operating equipment and lines, the insulation resistance should not be less than 1 MΩ/kV). The insulation resistance of low-voltage electrical appliances and their connecting cables and secondary circuits should generally not be less than 1 MΩ; in relatively humid environments, it should not be less than 0.5 MΩ; the insulation resistance of secondary circuit busbars should not be less than 10 MΩ. The insulation resistance of Class I hand-held power tools should not be less than 2 MΩ.
Insulation resistance: When a DC voltage is applied to a dielectric, after a certain period of polarization, the resistance corresponding to the leakage current flowing through the dielectric is called insulation resistance.
Reference standards:
EIA-364-21C
Equipment parameters:
Taiwan GW Instek / GPT-9803
Temperature rise
Temperature rise refers to the temperature of various components in electronic and electrical equipment above the ambient temperature. When current flows through a conductor, it generates a heating effect, and over time, the surface temperature of the conductor continuously rises until it stabilizes. The condition for stabilization is that the temperature difference within 3 hours does not exceed 2°C. The temperature measured at this point is the final temperature of the conductor, and the unit of temperature is degrees Celsius (°C). The portion of the temperature rise that exceeds the ambient air temperature is called the temperature rise, and the unit of temperature rise is Kelvin (K). Some articles, test reports, and exam questions on temperature rise often use degrees Celsius (°C) to represent temperature rise, which is inappropriate. It should be expressed as (K/W). To verify the lifespan, stability, and other characteristics of electronic products, the temperature rise of their important components (such as IC chips) is usually tested. The device under test is placed at a specific temperature (T=70°C) higher than its rated operating temperature (T=25°C), and after stabilization, the temperature rise of the components above the ambient temperature is recorded to verify the rationality of the product's design. In electrical products, the rated temperature rise of an electric motor refers to the maximum permissible temperature rise of the motor windings under the designed ambient temperature (plus 40℃). It depends on the insulation class of the windings. The temperature rise depends on the heat generation and heat dissipation during motor operation. The temperature rise is often used to judge whether the motor's heat dissipation is normal. Motor temperature refers to the actual heat generation temperature of various parts of the motor. It has a significant impact on the motor's insulation material; excessively high temperatures can cause insulation aging, shorten the motor's lifespan, and even lead to insulation failure. To prevent insulation aging and failure, the temperature of various parts of the motor, such as the windings, is subject to periodic limits; these temperature limits are the permissible temperatures of the motor.
Reference standards:
EIA-364-70B
Equipment parameters:
Agilent/34970
