Any semiconductor devices have inherently a certain rate of failure. The possibility of failure is greatly affected by the conditions in which they are used (circuit conditions, environmental conditions, etc.). This page describes precautions that must be observed to minimize the chance of failure and to obtain higher reliability from your FUJITSU SEMICONDUCTOR devices.
Precaution for Product Design
This section describes precautions when designing electronic equipment using semiconductor devices.
Absolute Maximum Ratings
Semiconductor devices can be permanently damaged by application of stress (voltage, current, temperature,etc.) in excess of certain established limits, called absolute maximum ratings. Do not exceed these ratings.
Recommended Operating Conditions
Recommended operating conditions are normal operating ranges for the semiconductor device. All the device's electrical characteristics are warranted when operated within these ranges.
Always use semiconductor devices within the recommended operating conditions. Operation outside these ranges may adversely affect reliability and could result in device failure.
No warranty is made with respect to uses , operating conditions, or combinations not represented on the data sheet. Users considering application outside the listed conditions are advised to contact their FUJITSU SEMICONDUCTOR sales representative beforehand.
Processing and Protection of Pins
These precautions must be followed when handling the pins which connect semiconductor devices to power supply and input/output functions.
Preventing Over-Voltage and Over-Current Conditions Exposure to voltage or current levels in excess of maximum ratings at any pin is likely to cause deterioration within the device, and in extreme cases leads to permanent damage of the device. Try to prevent such overvoltage or over-current conditions at the design stage.
Protection of Output Pins
Shorting of output pins to supply pins or other output pins, or connection to large capacitance can cause large current flows. Such conditions if present for extended periods of time can damage the device. Therefore, avoid this type of connection.
Handling of Unused Input Pins
Unconnected input pins with very high impedance levels can adversely affect stability of operation. Such pins should be connected through an appropriate resistance to a power supply pin or ground pin.
Semiconductor devices are constructed by the formation of P-type and N-type areas on a substrate. When subjected to abnormally high voltages, internal parasitic PNPN junctions (called thyristor structures) may be formed, causing large current levels in excess of several hundred mA to flow continuously at the power supply pin. This condition is called latch-up.The occurrence of latch-up not only causes loss of reliability in the semiconductor device, but can cause injury or damage from high heat, smoke or flame. To prevent this from happening, do the following:
Be sure that voltages applied to pins do not exceed the absolute maximum ratings. This should include attention to abnormal noise, surge levels, etc.
Be sure that abnormal current flows do not occur during the power-on sequence.
Observance of Safety Regulations and Standards
Most countries in the world have established standards and regulations regarding safety, protection from electromagnetic interference, etc. Customers are requested to observe applicable regulations and standards in the design of products.
Any semiconductor devices have inherently a certain rate of failure. You must protect against injury, damage or loss from such failures by incorporating safety design measures into your facility and equipment such as redundancy, fire protection, and prevention of over-current levels and other abnormal operating conditions.
Precautions Related to Usage of Devices
FUJITSU SEMICONDUCTOR devices are intended for use in standard applications (computers, office automation and other office equipment, industrial, communications, and measurement equipment, personal or household devices, etc.).Customers considering the use of our products in special applications where failure or abnormal operation may directly affect human lives or cause physical injury or property damage, or where extremely high levels of reliability are demanded (such as aerospace systems, atomic energy controls, sea floor repeaters, vehicle operating controls, medical devices for life support, etc.) are requested to consult with FUJITSU SEMICONDUCTOR sales representatives before such use. The company will not be responsible for damages arising from such use without prior approval.
Precautions for Package Mounting
For heat resistance during molding with solder, you should only mount under FUJITSU SEMICONDUCTOR 's recommended conditions. For detailed information about mount conditions, contact your FUJITSU SEMICONDUCTOR sales representative.
Surface mount packaging has long and thin leads, and therefore leads are more easily deformed or bent. The use of packages with higher pin counts and narrower pin pitch results in increased susceptibility to open connections caused by deformed pins, or shorting due to solder bridges. You must use appropriate mounting techniques. FUJITSU SEMICONDUCTOR recommends the solder reflow method, and has established a ranking of mounting conditions for each product. Users are advised to mount packages in accordance with FUJITSU SEMICONDUCTOR ranking of recommended conditions.
Storage of Semiconductor Devices
Because plastic chip packages are formed from plastic resins, exposure to natural environmental conditions will cause absorption of moisture. During mounting, the application of heat to a package that has absorbed moisture can cause surfaces to peel, reducing moisture resistance and causing packages to crack. To prevent, do the following:
Avoid exposure to rapid temperature changes, which cause moisture to condense inside the product. Store products in locations where temperature changes are slight.
Use dry boxes for product storage.
When necessary, FUJITSU SEMICONDUCTOR packages semiconductor devices in highly moisture-resistant aluminum laminate bags, with a silica gel desiccant. Devices should be sealed in their aluminum laminate bags for storage.
Avoid storing packages where they are exposed to corrosive gases or high levels of dust.
Because semiconductor devices are particularly susceptible to damage by static electricity, you must take the following precautions:
Avoid low humidity condition such as relative humidity 40%RH or less in the work environment. Use of an apparatus for ion generation may be needed to remove electricity.
Electrically ground all conveyors, solder vessels, soldering irons and peripheral equipment.
Eliminate static body electricity by the use of rings or bracelets connected to ground through high resistance (on the level of 1MΩ).Wearing of conductive clothing and shoes, use of conductive floor mats and other measures to minimize shock loads are recommended.
Ground all fixtures and instruments, or protect with anti-static measures.
Avoid the use of styrofoam or other highly static-prone materials for storage of completed board assemblies.
Precautions for Use Environment
Reliability of semiconductor devices depends on ambient temperature and other conditions as described above. For reliable performance, do the following:
Prolonged use in high humidity can lead to leakage in devices as well as printed circuit boards. If high humidity levels are anticipated, consider anti-humidity processing.
Discharge of Static Electricity
When high-voltage charges exist close to semiconductor devices, discharges can cause abnormal operation. In such cases, use anti-static measures or processing to prevent discharges.
Corrosive Gases, Dust, or Oil
Exposure to corrosive gases or contact with dust or oil may lead to chemical reactions that will adversely affect the device. If you use devices in such conditions, consider ways to prevent such exposure or to protect the devices.
Plastic molded devices are flammable, and therefore should not be used near combustible substances. If devices begin to smoke or burn, there is danger of the release of toxic gases.
Customers considering the use of FUJITSU SEMICONDUCTOR products in other special environmental conditions should consult with FUJITSU SEMICONDUCTOR sales representatives.