On July 1st, Toshiba Corporation's Semiconductor Company and Storage Products Company consolidated to form Semiconductor & Storage Products Company.This page describes reliability information of semiconductor products.
Optical Semiconductor Products
[As of April, 2011]
Section 1 describes the handling precautions common to all optical semiconductor devices, and Sections 2 to 6 describe the handling precautions for devices classified by product group. When using this document, be sure to read the precautions common to all devices in Section 1 as well as those specific to the device group used in your design.
- Precautions Common to All Optical Semiconductor Devices
- Visible LEDs (LED Lamps, LED Displays, LED Matrix Modules)
- Photosensors (Infrared LEDs, Photodetectors, Photointerrupters, Photoreflective Sensors)
- Photocouplers
- Fiber-Optic Devices
- Semiconductor Lasers
Safety Precautions
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Do not look into the laser beam or look through the optical system when a semiconductor laser is operating. Doing so may damage your eyesight or, in the worst case, cause blindness. When inspecting the optical characteristics of the laser using laser protective glasses, be sure the glasses comply with JISC6802. |
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The laser beams emitted from a device are extremely dangerous if they enter directly upon human eyes. Direct entering of Laser beams to human eyes may damage eyesight or, in the worst case, cause blindness. Therefore, designers of equipment that incorporate laser devices should include proper handling precautions and ways to avoid such dangers in accordance with JISC6802 in the instructions for workers engaged in inspection, test and equipment adjustments, and in the user's manuals for systems in which the device is mounted. |
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Do not apply voltage or current into the LED device that exceeds the device's absolute maximum rating. With resin-packaged LED devices in particular, excessive voltage or current may cause the package resin to explode, scattering resin fragments and may result injury. |
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When evaluating and testing the dielectric strength voltage of a photo coupler, use equipment that can shut off the supply voltage if a leakage current exceeding 100µA is detected. Failure to do so may result in the continuous flow of a large short-circuit current, causing the device to explode or combust, resulting in fire or injury. |
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When designing a semiconductor laser, use the built-in or another light-receiving element to stabilize optical output so as to ensure that laser beams exceeding the laser’s rated optical output are not emitted. If this stabilization function does not work properly and the laser beams output exceeds the rated output, not only the device may break down but also injury may result by the laser beam. |
1. Precautions Common to All Optical Semiconductor Devices
Moisture-Proof Packing
The conditions for moisture removal for moisture-proof packing of optical semiconductor devices differs from that used for regular plastic package devices packed in moisture-proof taping due to differences in their respective package resin characteristics. For details of moisture removal, refer to the individual technical datasheets and databooks for each device.
Design
- Derating
The lifetime characteristics of optical semiconductor devices are closely associated with operating conditions, case temperature and the operating humidity environment. From this perspective, in addition to regular derating, the fluctuation and deterioration rates for each of the device’s primary characteristics (such as luminous intensity, optical output and current conversion efficiency), and the operating and environment conditions should be fully taken into consideration at the design stage. - Fail-Safe Implementation
If there is a possibility that failure in optical semiconductor device, deterioration of characteristics (such as luminous intensity, optical output, current conversion efficiency or laser light output) or functional abnormality will have a significant adverse impact on the safe operation of the system, design a fail-safe measure in accordance with the system application.
Inspection, Test and Evaluation
When inspecting devices, be sure to observe the standards stated in the individual technical datasheets and databooks for each device. In particular, the reverse voltage/reverse current characteristics differ according to the type of light-emitting material. If current is forced to flow in the reverse polarity, device characteristics can fail at a high rate.
Safety Standards
The resin used in packages where light transmittance is an important characteristic does not meet the combustion resistance required in safety standards. Because resin is not self-extinguishing, it can not only generate poisonous gases when burned but also cause secondary ignition. During the mounting design phase, be sure to take this into account when selecting the ambient environment and casing material.
Disposal
For details of the precautions related to device disposal, refer to the relevant databook.
2. Visible LEDs
Impact and Vibration
- Matrix Modules
If an excessive impact is applied to the device packing, the relative positions of the display substrate and drive substrate may shift, making it impossible to mount the device using the specified installation pitch.
Design
- Application
LED lamps are devices designed for display purposes. Using an LED lamp as a photosensor light source is prohibited. If a light source for a photosensor is required, choose a device developed specifically for that purpose. - Heat Radiation
For display systems formed using an array of visible LED devices, be sure to sufficiently take into account heat radiation. Partial temperature non-equilibrium should be taken into account since it may reduce luminous intensity due to temperature dependency caused by the physical properties of the LED device, impairing the device’s display quality and giving rise to differences in the luminous intensity deterioration characteristics. - Eyesight Protection
The safety of visible LEDs with respect to eyesight as defined in IEC825-1 applies to end products, not to individual LED lamps. In consequence, when designing LEDs external optical systems and LEDs operating conditions, the safety of the end product (set) with respect to the human eye should be taken into account. - Chemical Resistance
In the case of resin-package devices in particular, failure to select an appropriate chemical for washing and wiping may change the resin characteristics, adversely affecting optical characteristics and reliability. That is, when an inappropriate chemical is used, chemical changes in the resin may alter the optical characteristics of the device, causing cracks in the package resin. Therefore, when selecting a new chemical, first conduct evaluations in advance or confirm your nearest Toshiba office or distributor. - Lifetime Characteristics
The lifetime of LEDs is greatly affected by the operating conditions and operating environment as well as the characteristics specific to the device. In consequence, it is recommended that lifetime characteristics be checked before selecting the LED device. If control of the light output fluctuation rate is required, Toshiba suggests constructing a system which operates using a control circuit based on a light output monitor, or a system which can adjust light output using such as an alarm display. - Usage Restrictions
With GaAlAs LEDs, a light-adsorption layer forms on the chip surface when current is applied, sometimes reducing luminous intensity. In consequence, it is recommended that lifetime characteristics be checked before selecting the device. With high-temperature, high-humidity environments especially, usage restrictions are required.
Mounting
- Mounting LED Lamps with Radial Taping
LED lamps employ leads made of relatively hard material. Thus, the lifetime of the clinch-cut blades can be significantly shortened if, for instance, the timing of the clinching and cutting of an automatic mounting device becomes out of synchronization for each lead. Adequate coordination and maintenance are required. - Prohibition of Stress on Resin Packages
With automatic mounting, selection of devices with stoppers installed on the lead roots is recommended. If the leads do not have stoppers, the tensile stress applied during clinching may cause stress on the package’s resin area, deteriorating reliability. - Designing the Hole Diameter on Printed Circuit Boards
Do not design the lead insertion holes on PCBs with diameters greater than the values recommended by the manufacturer of the automatic mounting device. Setting the appropriate hole diameter will reduce stress on the package’s resin area during lead clinching and prevent solder holes forming.
Operating Environment
When voltage is applied to the optical devices under high humidity, shorts is possible to occur between electrode metals due to ion migration. Particularly, if voltage is applied to the devices under dew condensation, ion migration is more possible to occur. To prevent this problem, it should be coated with moisture - proof materials on the printed circuit board mounted the optical devices and the driver circuits.
3. Photosensors
Design
- Application
Use of a visible LED lamp designed for displays as a light source for a photosensor is prohibited.
If a light source for a photosensor is required, choose a device developed specifically for that purpose. - Reliability Design
The optical output of LED devices is closely associated with factors such as the device’s operating conditions, package temperature and operating humidity environment. If the deterioration of optical output critically hinders system safety, design a safety measure, such as a closed loop control for radiant intensity using a radiant intensity monitor, or some other fail-safe measure. - Dust and Oil
Dust accumulated on or oil adhesion to the lens surface of a device may affect the device’s optical characteristics, making it impossible to obtain the designed optical output or light sensitivity. Also, the dust or oil may generate a chemical reaction with the device, having an adverse effect similar to corrosive gas on the device.
Mounting
- Lens Cleaning and Level Shift
To prevent system malfunction due to the deterioration of characteristics caused by an accumulation of dust on the lens surfaces of light emitting and light receiving parts, Toshiba recommends that you periodically wipe off accumulated dust. After cleaning, check to see if the photosensor operates properly and that no level shift has occurred.
4. Photocouplers
Design
- Dust and Oil
Dust accumulation on or oil adhesion to devices causes a reduction in the device’s dielectric strength between the input and the output. Also, the dust or oil may generate a chemical reaction with the device, having an adverse effect similar to corrosive gas on the device. If a reduction in the input-to-output dielectric strength of a device or an increase in leakage current through its package could critically affect system functionality, measures such as resin impregnation should be considered during at the design phase. - Observing the Operating Range
The lifetime characteristics of a light-emitting device are closely associated with factors such as operating current and package temperature. From this standpoint, in addition to regular derating, the relationship between the fluctuation rate of the coupling characteristics of the device, such as the current transfer ratio (CTR) and trigger LED current (IFT), and the operating current and operating temperature should be fully taken into account in the design phase. - Combustibility of Package Resin
The resin used in packages is a V-0 grade resin under UL-94 standards. However, since this resin is not non-combustible, it may emit smoke or ignite if subjected to abnormal heating beyond its combustion temperature. To prevent the propagation of fire caused by a smoking or ignited Toshiba product and to ensure that Toshiba products do not emit smoke or ignite due to surrounding conditions, do not use Toshiba products in close proximity to a combustible thing, heat-generating thing, igniting material or flammable materials.
Inspection, Test and Evaluation
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When evaluating and testing the dielectric strength voltage of a photo coupler, use equipment that can shut off the supply voltage if a leakage current exceeding 100µA is detected. Failure to do so may result in the continuous flow of a large short-circuit current, causing the device to explode or combust, resulting in fire or injury. |
- Dielectric Strength of a Device Between Input and Output
- Control Standards and Mounting Restrictions
The performance of Dielectric Strength of a Device Between Input and Output is stipulated and tested based on methods defined in UL (American), VDE (German) and other component standards. The stipulated insulation performance retention time for devices is 1 minute. Therefore, use of these devices in applications designed to provide long-term continuous high-voltage insulation is not recommended.
- Control Standards and Mounting Restrictions
Mounting
- Resin Impregnation
- Before applying resin impregnation, check that it will not affect the device.
- Before applying resin impregnation, first clean off the dirt and impurities and remove the moisture from the device adequately. For the resign impregnation method, inform the resin manufacturer of the voltages applied between the device’s input and output and follow their instructions.
Usage Environment
Light striking a semiconductor device generates electromotive force due to photoelectric effects, it may cause malfunction. Strong light such as sunlight, strobe light or a search light exposing upon a photocoupler-based system may cause the system to malfunction. A device light-shield suitable to the application is required.
5. Fiber-Optic Devices (TOSLINK)
Design
- External Noise
To improve the noise resistance of an optical reception module (simplex type) and transmission/reception module (duplex type), connect the module’s package-fixing reinforcement pins to the "SIGNAL-GND" when mounting. At this time, make sure that the module’s package does not touch the power supply lines or any other circuits. - When using an optical transmission or reception module or an optical transmission/reception module in a location that is easily affected by noise, test the device’s noise resistance in advance and take the following measures as necessary:
- If power supply ripples are large, enhance the noise filter connected to the power supply line.
- Cover the optical transmission or optical reception module or optical transmission/reception module and the power supply filter with metal covers to enhance the shield. At this time, make sure the module’s case does not come in contact with the metal cover.
- Dust and Oil
Devices do not employ a dust-proof mechanism. When using a device in a dusty environment or in a location where oil may splash, incorporate a dust-proofing cover that will enclose all and protect the optical transmission/reception module with the optical fibers (and connectors) connected. - Vibration
When mounting optical modules in equipment subjected to a great amount of vibration, resonance or mechanical shock, incorporate a structural measure into the design to alleviate the effects. In particular, if a system with optical fibers (and optical connectors) installed is subjected to vibration or shock, the optical module’s package-fixing reinforcement pins may be sheared by inertial stress. So, attention is required.
Optical modules in ceramic packages are hollow and therefore require even more consideration with regard to vibration, resonance and shock in comparison with the resin-molded type. - Laying Optical Fiber Cables
When laying optical fiber cables, bend them at six to 10 times of the stipulated minimum bending radius.
Inspection, Test and Evaluation
- Optical Reception Module Output Pins
Do not connect the output pins directly to the power supply or GND.
Doing so can cause a large current to flow into the device, and the device may break down.
If the output pins need to be pulled up or pulled down, be sure to connect a resistor.
For details on how to select the resistance value, refer to the individual technical datasheets and databooks for the device.
Mounting
Since optical transmission/reception modules are optical components, avoid using a soldering method that will be adversely affected by flux. In addition, cleaning is not recommended. When installing optical transmission/reception modules onto a printed circuit board, follow the sequence below:
- Solder the circuit components other than the optical transmission/reception module.
- Clean the board.
- Solder the optical transmission/reception module using a solder iron.
Maintenance
- When an optical module is not in use, attach a protective cap to the optical connector insertion area. Light (including external light) entering on an optical module with no protective cap particularly an optical reception module, may adversely affect the other circuits.
- Toshiba recommends that you stipulate in system maintenance specifications that the system’s fiber-optical output be periodically checked.
6. Semiconductor Lasers
Design
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The laser beams emitted from a device are extremely dangerous if they enter directly upon human eyes. Direct entering of Laser beams to human eyes may damage eyesight or, in the worst case, cause blindness. Therefore, designers of equipment that incorporate laser devices should include proper handling precautions and ways to avoid such dangers in accordance with JISC6802 in the instructions for workers engaged in inspection, test and equipment adjustments, and in the user’s manuals for systems in which the device is mounted. |
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When designing a semiconductor laser, use the built-in or another light-receiving element to stabilize optical output so as to ensure that laser beams exceeding the laser's rated optical output are not emitted. If this stabilization function does not work properly and the laser beams output exceeds the rated output, not only the device may break down but also injury may result by the laser beam. |
- Head Radiation
Large amounts of heat emanate from the PN junctions of semiconductor lasers, a sufficient level of heat radiation is necessary.
Semiconductors laser chips are constructed in such a way that the heat is efficiently conducted to the heat radiating section of the package.
Metal can packages require a design that ensures that the external heat sink sufficiently contacts the flange section.
For lead frame type open packages, attach closely the heat-radiating surface at the bottom of the product and the external heat sink.
To further improve heat radiation, apply an approximate 5N load evenly on the cap section on top of the product. When such a load is applied, the material and surface status of the external heat sink affect the heat radiation characteristics of the device . Be sure, therefore, to set a load after sufficient verification of the effects. - Dust and Dew Condensation
For lead frame type open packages, avoid operation under conditions of dew condensation.
Operation with dew condensation may result not only in deterioration of the product’s optical characteristics, but also device breakdown caused by internal shorts.
In addition, for lead frame type open packages, take care to ensure that dirt does not adhere to the chip end surface.
Also, when using silicon grease for heat radiation, be careful that the grease does not adhere to the chip end surface. - Operation under High Temperature, High Humidity for Extended Periods
For open packages with built-in monitor photodiodes, do not apply bias voltage to the photodiodes. - Power Supplies and External Noise
Before operating a product, check that the product does not exceed the absolute maximum ratings due to the spike currents generated when the power is turned on or off.
If chattering or overshoot is observed, incorporate a filter such as a CR circuit or a soft start circuit into your design to eliminate the noise.
In addition, when induced noise or surge voltages are applied from external sources, the rated output may be exceeded, causing the device to break down. For this reason, Toshiba recommends carrying out protective measures.
Inspection, Test and Evaluation
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Do not look into the laser beam or look through the optical system when a semiconductor laser is operating. Doing so may damage your eyesight or, in the worst case, cause blindness. When inspecting the optical characteristics of the laser using laser protective glasses, be sure the glasses comply with JISC6802. |
Mounting
Metal Can Packages
- When installing a device to a heat sink, fix it by its flange.
Avoid pinching the device’s cap by the heat sink, because pinching the device’s cap by the heat sink will cause damage to the window glass.
When using screws to install the device’s flange to the heat sink, tighten the screws in stages to approximately 0.8Nm. Do not tighten one screw fully before tightening the rest. - Device packages are hermetically sealed. Applying excessive stress to the area between the lead and case or glass surfaces will cause the hermetic seal to degrade.
- Be careful not to scratch or stain the window glass. The device’s optical output may decrease or the far-field pattern may become deformed. In addition, avoid wiping the glass surface to remove adhered dirt with such as cotton swabs. This can make another scratch on the window glass.
- Avoid cleaning the devices. Not only does cleaning reduce the adhesive strength of the window glass, it also causes a decrease in the device’s optical output or deformation of the far-field pattern due to impurities adhering to the window glass.
Lead Frame Type Open Packages
- Use the product with an aluminum or copper heat sink attached closely to the heat radiating bottom surface.
To further improve radiation performance stability, apply an approximate 5N load evenly on the cap section on top of the product. - Do not apply excessive loads to the package cap. In addition, avoid applying loads that accumulate at a single point. Doing so will not only cause fluctuation of the monitor current value of the built-in monitor photodiode, but also cap deformation and breakdown.
- Do not excessively twist or apply impact to the product before installing the product to the heat sink.
- Fix the product by not only applying a load to the cap but by also fixing the product wing area using an adhesive or screws.
- The product package is not hermetically sealed. Avoid operation under conditions of dew
condensation.
Operation under conditions of dew condensation may not only result in deterioration of the product’s optical characteristics, but also in device breakdown caused by internal shorts.
Also, avoid cleaning the products. - When assembling the device to equipment, pay attentions to ensure that dirt does not adhere to the chip end on the front of the product. Also, give due attention to ventilation to ensure that organic gases emitted from radiated material and fixing adhesives do not accumulate in the product interior. The effect on the product interior differs according to the adhesive or radiated material. Be sure to conduct a thorough product check after curing, including a high-temperature operation test.
- Combustibility of Package Resin
The resin used in packages is a V-HB grade resin under UL-94 standards. However, since this resin is not non-combustible, it may emit smoke or ignite if subjected to abnormal heating beyond its combustion temperature. To prevent the propagation of fire caused by a smoking or ignited Toshiba product and to ensure that Toshiba products do not emit smoke or ignite due to surrounding conditions, do not use Toshiba products in close proximity to a combustible thing, heat-generating thing, igniting material or flammable materials.
On July 1st, Toshiba Corporation's Semiconductor Company and Storage Products Company consolidated to form Semiconductor & Storage Products Company.This page describes reliability information of semiconductor products.