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The following information may be useful in developing processes for handling and assembly using National Semiconductor Products.
Dry Pack
Why does National Dry Pack?
When there is a significant amount of moisture in a plastic surface mount package, the solder reflow process can cause a crack that extends from the die attach pad to the bottom surface of the package. The crack gives contaminants a direct path to the package die.
To eliminate the package-cracking problem, National's moisture-sensitive SMDs are dry packed with desiccant in hermetically sealed shipping bags within their maximum allowed moisture exposure time. If this time is exceeded, bake is done immediately prior to final pack.
For Additional Information: Dry Pack and Handling and MSL Rating (pdf 179KB)
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Shelf Life of Packaged Integrated Circuits
Typically, material shipped direct from NATIONAL SEMICONDUCTOR to the customer is less than 2 year old from date of manufacture.
The Maximum storage temperature/RH for dry-pack parts is 36 months at <=40°C / 90%RH. The Maximum storage temperature/RH for non dry-pack parts is 36 months at <= 30°C / 85% RH.
If prolonged shelf life is desired with respect to solderability, it is recommended to use a hermetic bag with desiccant. Following prolonged storage, a series of tests is recommended prior to board assembly e.g.,
- Solderability Test,
- Functional Test, and
- Check of humidity indicator. If the humidity indicator has expired, we recommend baking the parts according to JEDEC Standard J-STD- 033A.
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Sales Dice and Chip On Glass (COG) Storage
Proper storage conditions are necessary to prevent product contamination and/or degradation after shipment from National Semiconductor Corp.
1.0 Sales Dice & Sales Wafer
1.1 Unsawn wafers and singulated die can be stored for up to 12 months when in the original sealed packaging at room temperature (45% +/- 15% RH controlled environment).
1.2 Unsawn wafers and singulated die that have been opened can be stored for up to 30 days when returned to their containers and placed in a Nitrogen purged cabinet, at room temperature (45% +/- 15% RH controlled environment).
Note: To reduce the risk of contamination or degradation, it is recommended that product not being used in the assembly process be returned to their original containers and resealed with a vacuum seal process.
1.3 Die shipped as sawn wafers on film frames or die shipped as tape & reel with Surf Tape® carrier tape have a shelf life of 6 months when in the original sealed packaging at room temperature. This is primarily due to the nature of the adhesive tape used for mounting the product.
2.0 COG
2.1 Can be store for up to 24 months when in the original sealed packaging at room temperature (45% +/- 15% RH controlled environment).
2.2 COG die that have been opened can be stored for up to 30 days when returned to their containers and placed in a Nitrogen purged cabinet, at room temperature (45% +/- 15% RH controlled environment).
Note: To reduce the risk of contamination or degradation, it is recommended that product not being used in the assembly process be returned to their original containers and resealed with a vacuum seal process.
In all cases, the customer must determine the applicability of extended storage durations and conditions with respect to their assembly process and end product criteria.
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Recommended Soldering Profiles
The following document reflects recommended parameter profiles for various soldering technique/technology choices.Recommended Soldering Profiles (pdf 47KB)
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Traceability Systems
- Backward traceability to die run number based on part marking
- Forward traceability to Customer based on manufacturing details
- Root causes can be identified quickly, down to responsible process step: e.g. Machine, Operator, etc.
- Extent of problem can be determined accurately, narrowing the impact to only affected Lots / Customers
- Efficient containment plan can be implemented.
- Impact is reduced by timely, accurate Problem Notification
- Corrective action made possible by knowledge of ROOT CAUSE
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ESD Protection
Prevent ESD Damage to IC's, Boards, and Electronic Products
Virtually all semiconductor devices are subject to damage by an electrostatic discharge (ESD) event. While some can withstand tens of thousand of volts before damage, some can be damaged by less than 200 volts. To avoid this, it is important that proper precautions and handling procedures be understood and followed.
People tend to believe their senses. If they don't see or feel it, they assume nothing happened. However, because IC's can be easily damaged by ESD voltages that are not "felt," people can be fooled. While they may not feel the event, the circuit did.
All IC manufacturers and users should be aware of the adverse results ESD can have on product reliability, along with the impact on product quality and cost. To help with this awareness, National Semiconductor prints ESD caution and warning symbols on the protective packaging containing its products.
These industry standard ESD symbols are printed on the packing material to notify distributors and users that ESD precautions and proper handling procedures must be utilized to insure the reliability and quality of both the IC's inside as well as the electronic end products that will utilize them.
This page provides basic information on the key principles of ESD protection. National Semiconductor's employees, distributors and customers must implement these practices in order to protect products.
Basic Electrostatic Discharge Information
ESD is the rapid flow of electrons between two bodies of unequal charge. It can also occur between one charged body and ground with an electronic circuit being the path of least resistance between the two. It generally occurs when ESD handling precautions are overlooked or inadequate.
The sensitivity of IC's to ESD is classified according to the voltage levels that may cause potential damage. There are three classes as shown in the table below.
| Class |
Sensitivity Level |
| Class 1 |
Less than 1,000 volts |
| Class 2 |
1,000 to 4,000 volts |
| Class 3 |
4,000 to 15,000 volts |
Protected Work Area
A protected work area must be provided wherever ESD sensitive parts, assemblies and equipment are handled. This protected area must be constructed, equipped and maintained with the necessary ESD protective materials and equipment to insure that voltages are below the sensitivity level of the most ESD sensitive item handled in the work place.
EIA-625 (Requirements for Handling Electrostatic Discharge Sensitive Devices) is a good specification to use as a reference. It identifies the key elements in handling ESD devices. It also provides a check list for performing an ESD handling audit.
An ESD protected work area should address the following items:
- Grounded ESD protective work surface
- ESD safe flooring (mats or permanent installed ESD flooring)
- Personnel grounding (wrist straps or ESD shoes in conjunction with grounded ESD flooring)
- Removal or control of static generating sources so that no voltages are present greater than the threshold established for safe ESD handling of the most sensitive device used.
- Usage of ESD smocks when personnel's clothing generates charges greater than the established threshold
- Installation of air ionizers where essential equipment and material exceed the established threshold
- Identification of ESD safe workstations
All items included in the protected work area should be tested at a prescribed frequency to insure their continued effectiveness. The EIA-625 specification provides minimum frequencies and acceptable measurement limits. Measurement records should be maintained for at least two years.
Other Precautions
To maintain a high level of quality, audits should be performed on each operation where processing, handling, and storage of ESD sensitive devices occur. Each operation should be audited at least annually with audit records kept for a minimum of two years.
ESD training programs help ensure all personnel have a basic understanding of safe handling procedures and are capable of applying their knowledge in the workplace. Training records should also be maintained for a minimum of two years.
There are various types and brands of inspection, test, measuring and monitoring equipment involved in proper ESD operations. Equipment should be selected based on the need to measure voltages of the established threshold and greater. It must be capable of measuring all the elements of the ESD work area. This equipment also needs to be properly maintained. This should be controlled by a calibration system that is compliant with MIL-STD 45662 or ANSI/ASQC-Q900s and ANSI/ASQC-M1.
Other Sources of Information
It may be a real advantage to have membership in an organization such as the ESD Association to stay current with the industry and its standards. Identify someone who is current in ESD to take a leadership role in a good ESD program to insure compliance and continuous improvement.
As with most things, there are many ESD related web sites on the Internet that can provide additional, and more detailed, information.
EOS/ESD Information
A reference derived from the knowledge gained at National Semiconductor's own Quality, Reliability, and Failure Analysis Groups.
http://www.eosesd.org
The ESD Association promotes the exchange of technical information focusing on the advancement of the theory and practice of electrical overstress avoidance with an emphasis on the electrostatic discharge phenomena.
http://www.esdjournal.com
The ESD Journal provides timely information on topics ranging from electrostatic discharge, static electricity, laboratories, testing and consulting to instruments and vendors.
http://www.eia.org
The Electronic Industries Alliance encompasses several industry sectors and groups
http://www.ansi.org
The American National Standards Institute's on-line site provides information on the latest national and international standards-related activities
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