Burn-in Testing
Burn-in testing is the process by which a system detects early failures in semiconductor components (infant mortality), thereby increasing a semiconductor component reliability. Normally burn-in tests are performed on electronic devices such as laser diodes with an Automatic Test Equipment laser diode burn-in system that runs the component for an extended period of time to detect problems.
A burn-in system will use cutting-edge technology to test the component and provide precision temperature control, power and optical (if required) measurements to ensure the precision and reliability required for manufacturing, engineering evaluation, and R&D applications.
Burn-in testing may be conducted to ensure that a device or system functions properly before it leaves the manufacturing plant or to confirm new semiconductors from the R&D lab are meeting designed operating requirements.
It is best to burn-in at the component level when the cost of testing and replacing parts is lowest. Burn-in of a board or an assembly is difficult because different components have different limits.
It is important to note that burn-in test is usually used to filter out devices that fail during the “infant mortality stage” (beginning of bathtub curve) and does not take into count the “lifetime” or wearout (end of the bath tub curve) – this is where reliability testing comes into play.
Wearout is the natural end-of-life of a component or system related to continuous use as a result of materials interaction with the environment. This regime of failure is of particular concern in denoting the lifetime of the product. It is possible to describe wearout mathematically allowing the concept of reliability and, hence, lifetime prediction.
What Causes Components to Fail During Burn-in?
The root cause of fails detected during burn-in testing can be identified as dielectric failures, conductor failures, metallization failures, electromigration, etc. These faults are dormant and randomly manifest into device failures during device life-cycle. With burn-in testing, an Automatic Test Equipment (ATE) will stress the device, accelerating these dormant faults to manifest as failures and screen out failures during the infant mortality stage.
Burn-in testing detects faults that are generally due to imperfections in manufacturing and packaging processes, which are becoming more common with the increasing circuit complexity and aggressive technology scaling.
Burn-in Testing Parameters
A burn-in test specification varies depending on the device and testing standard (military or telecom standards). It usually requires the electrical and thermal testing of a product, using an expected operating electrical cycle (extreme of operating condition), typically over a time period of 48-168 hours. The thermal temperature of the burn-in test chamber can range from 25°C to 140°C .
Burn-in is applied to products as they are made, to detect early failures caused by faults in manufacturing practice.
Burn In Fundamentally performs the following:
Stress + Extreme Conditions + Prolong Time = Acceleration of “Normal/Useful life”
Types of Burn-in Tests
Dynamic Burn-in : the device is exposed to high voltage and temperature extremes while being subjected to various input stimuli .
A burn-in system applies various electrical stimuli to each device while the device is exposed to extreme temperature and voltage. The advantage of dynamic burn-in is its ability to stress more internal circuits, causing additional failure mechanisms to occur. However, dynamic burn-in is limited because it cannot completely simulate what the device would experience during actual use, so all the circuit nodes may not get stressed.
Static Burn-in : Device under test (DUT) is stressed at elevated constant temperature for an extended period of time.
A burn-in system applies extreme voltage or currents and temperatures to each device without operating or exercising the device. The advantages of static burn-in are its low cost and simplicity.
How is a Burn-In Test Performed?
The semiconductor device is placed onto special Burn-in Boards (BiB) while the test is executed inside special Burn-in Chamber (BIC).
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Burn-in Chamber
A burn-in chamber is an environmental oven used to evaluates the reliability of multiple semiconductor devices and performs large capacity screenings for premature failure (infant mortality). These environmental chambers are designed for static and dynamic burn-in of integrated circuits (ICs) and other electronic devices such as laser diodes.
Selecting Chamber Size
The chamber size depends on the size of the burn-in board, the number of products in each burn-in board, and the number of batches required per day to meet production requirements. If the interior space is too small, insufficient space between parts results in poor performance. If it is too large, space, time and energy are wasted.
Companies that are purchasing a new burn-in set-up should work with the vendor to ensure the heat source has enough steady-state and maximum capacity to match the load for the DUT.
When using forced recirculating airflow, parts benefit from spacing, but the oven can be loaded more densely vertically because airflow is distributed along the entire side wall. Parts should be kept 2-3 inches (5.1 – 7.6cm) from the oven walls.
Burn-in Chamber Design Specs
Temperature Range
Depending on the requirements of the Device Under Test (DUT) select a chamber that has a dynamic range such as 15°C above ambient to 300°C (572°F)
Temperature Accuracy
It is important that the temperature does not fluctuate. Uniformity is the maximum difference between the highest and lowest temperatures in a chamber at a specified setting. A specification of at least 1% setpoint for uniformity and 1.0°C control accuracy is acceptable in most semiconductor burn-in applications.
Resolution
A high-temperature resolution of 0.1°C will provide the best control to meet burn-in requirements
Environmental Savings
Consider a burn-in chamber that has a refrigerant that has a zero ozone layer depletion coefficient. Burn-in chambers with refrigeration are related to chambers operating in temperatures below 0 degrees Celsius down to – 55°C.
Chamber configuration
The chamber can be designed with card cages, card-slots, and access doors to simplify connecting DUT boards and driver boards with ATE stations.
Chamber Air Flow
In most cases a forced convection oven with recirculating airflow will provide the best distribution of heat and significantly speeds the time-to-temperature and heat transfer to parts. Temperature uniformity and performance depends on a fan design that directs air to all areas of the chamber.
The chamber can be design with a horizontal or vertical airflow. It is important to know the direction of inserting the DUT based on the airflow of the chamber.
Custom ATE Wiring
When it comes to measuring over hundreds of devices, inserting wires through an aperture or test hole may not be practical. Custom wiring connectors can be mounted directly to the oven to facilitate the electrical monitoring of the device with an ATE.
How A Burn-in Oven Controls Temperature
The burn-in oven uses a temperature controller executing a standard PID (proportional, integral, derivative) algorithm. The controller senses the actual temperature value versus the desired setpoint value, and issues corrective signals to the heater calling for application ranging anywhere from no heat to full heat. A fan is also used to equalize the temperature through the chamber.
The most common sensor used for accurate temperature control of the environmental oven is a Resistance Temperature Detector (RTD) which a platinum-based unit typically referred to as a PT100.
Sizing The Chamber
If you are using an existing oven, basic thermal modelling based on factors such as the oven’s thermal capacity and losses, heat-source output, and DUT mass will allow you to verify that the oven and heat source are sufficient to reach desired temperature with a thermal time constant short enough for tight loop response under the controller’s direction.
High Temperature Aging Cabinet
High temperature aging cabinet is a type of aging equipment used to remove early failure of non-conforming product parts.
Use of temperature aging cabinet, aging oven:
This test equipment is a test equipment for aviation, automobile, home appliances, scientific research and other fields, which is used to test and determine the parameters and performance of electrical, electronic and other products and materials after temperature environment changes in high temperature, low temperature, alternating between temperature and humidity or constant temperature and humidity.
The chamber of the test equipment is sprayed with steel plate after treatment, and the spray color is optional, generally beige. SUS304 mirror stainless steel is used in the inner room, with a large window tempered glass, real-time observation of internal aging products.
Features of temperature aging cabinet, aging oven:
1. PLC processing industry touch screen programming combination control, balanced temperature control system: aging specimen room temperature rise start the ventilation fan, balance the sample heat, aging cabinet is divided into product area and load area
2. PID+SSR temperature control system: according to the temperature change in the specimen box, the heat of the heating tube is automatically adjusted to achieve the temperature balance, so that the heating heat of the system is equal to its heat loss and achieve the temperature balance control, so it can run stably for a long time; The fluctuation of temperature control is less than ±0.5℃
3. The air transport system is composed of three-phase asynchronous electronic multi-wing wind wheel and wind drum. The wind pressure is large, the wind speed is uniform, and the uniformity of each temperature point is met
4. High precision PT100 platinum resistance for temperature acquisition, high accuracy for temperature acquisition
5. Load control, the load control system provides ON/OFF control and timing control two functional options to meet the different test requirements of the product
(1)ON/OFF function introduction: The switch time, stop time, and cycle times can be set, the test product can be switched according to the setting requirements of the system, the stop cycle control, the aging cycle number reaches the set value, the system will automatically sound and light prompt
(2) Timing control function: the system can set the running time of the test product. When the load starts, the product power supply starts timing. When the actual timing time reaches the time set by the system, the power supply to the product is stopped
6. System operation safety and stability: The use of PLC industrial touch screen control system, stable operation, strong anti-interference, convenient program change, simple line. Perfect alarm protection device (see protection mode), real-time monitoring of the operating status of the system, with the function of automatic maintenance of temperature data during operation, in order to query the temperature historical data when the product is aging, the data can be copied to the computer through the USB interface for analysis (format is EXCEL), with historical data curve display function, It intuitively reflects the temperature change in the product area during the product test, and its curve can be copied to the computer in BMP format through the USB interface, so as to facilitate the operator to make the test product report. The system has the function of fault query, the system will automatically record the alarm situation, when the equipment fails, the software will automatically pop up the alarm screen to remind the cause of the fault and its solution; Stop the power supply to the test product to ensure the safety of the test product and the equipment itself, and record the fault situation and occurrence time for future maintenance.
Semiconductor Chip-Car Gauge Chip
A new energy vehicle is divided into several systems, MCU belongs to the body control and vehicle system, is one of the most important systems.
MCU chips are divided into 5 levels: consumer, industrial, vehicle gauge, QJ, GJ. Among them, the car gauge chip is the current vane product. So what does the car gauge chip mean? From the name, it can be seen that the car gauge chip is the chip used in the car. Different from ordinary consumer and industrial chips, the reliability and stability of the car gauge chip is extremely important, so as to ensure the safety of the car at work.
The certification standard of the car gauge level chip is AEC-Q100, which contains four temperature levels, the smaller the number, the higher the level, the higher the requirements for the chip.
It is precisely because the requirements of the car gauge chip are so high, it is necessary to carry out a strict Burn In test before the factory, BI test requires the use of professional BI oven, our BI oven can meet the BI test of today's car gauge chip.
Connect the EMS system, so that each batch of baked chips can be traced at any time. High temperature and low temperature vacuum anaerobic environment, real-time monitoring of baking curve to ensure baking safety and effect.
Burn-in Oven
Burn-in is an electrical stress test that employs voltage and temperature to accelerate the electrical failure of a device. Burn-in essentially simulates the operating life of the device, since the electrical excitation applied during burn-in may mirror the worst-case bias that the device will be subjected to in the course of its useable life. Depending on the burn-in duration used, the reliability information obtained may pertain to the device's early life or its wear-out. Burn-in may be used as a reliability monitor or as a production screen to weed out potential infant mortalities from the lot.
Burn-in is usually done at 125 deg C, with electrical excitation applied to the samples. The burn-in process is facilitated by using burn-in boards (see Fig. 1) where the samples are loaded. These burn-in boards are then inserted into the burn-in oven (see Fig. 2), which supplies the necessary voltages to the samples while maintaining the oven temperature at 125 deg C. The electrical bias applied may either be static or dynamic, depending on the failure mechanism being accelerated.
Figure 1. Photo of Bare and Socket-populated Burn-in Boards
The operating life cycle distribution of a population of devices may be modeled as a bath tub curve, if the failures are plotted on the y-axis against the operating life in the x-axis. The bath tub curve shows that the highest failure rates experienced by a population of devices occur during the early stage of the life cycle, or early life, and during the wear-out period of the life cycle. Between the early life and wear-out stages is a long period wherein the devices fail very sparingly.
Figure 2. Burn-in ovens
Early life failure (ELF) monitor burn-in, as the name implies, is performed to screen out potential early life failures. It is conducted for a duration of 168 hours or less, and normally for only 48 hours. Electrical failures after ELF monitor burn-in are known as early life failures or infant mortality, which means that these units will fail prematurely if they were used in their normal operation.
High Temperature Operating Life (HTOL) Test is the opposite of ELF monitor burn-in, testing the reliability of the samples in their wear-out phase. HTOL is conducted for a duration of 1000 hours, with intermediate read points at 168 H and 500 H.
Although the electrical excitation applied to the samples are often defined in terms of voltages, failure mechanisms accelerated by current (such as electromigration) and electric fields (such as dielectric rupture) are understandably accelerated by burn-in as well.
Lab Ovens and Lab Furnaces
Design with sample protection as the primary goal
Lab ovens are an indispensable utility for your daily workflow, from simple glassware drying to very complex temperature-controlled heating applications. Our portfolio of heating and drying ovens provides temperature stability and reproducibility for all your application needs. LABCOMPANION heating and drying ovens are designed with sample protection as a primary goal, contributing to superior efficiency, safety and ease of use.
Understand natural and mechanical convection
Principle of natural convection:
In a natural convection oven, hot air flows from bottom to bottom, so that the temperature is evenly distributed (see figure above). No fan actively blows the air inside the box. The advantage of this technology is ultra-low air turbulence, which allows for mild drying and heating.
Principle of mechanical convection:
In a mechanical convection (forced air drive) oven, an integrated fan actively drives the air inside the oven to achieve uniform temperature distribution throughout the chamber (see figure above). A major advantage is excellent temperature uniformity, which enables reproducible results in applications such as material testing, as well as for drying solutions with very demanding temperature requirements. Another advantage is that the drying rate is much faster than natural convection. After opening the door, the temperature in the mechanical convection oven will be restored to the set temperature level more quickly.
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