ESD TR Handbook for the Development of an Electrostatic Discharge Control Program for the Protection of Electronic Parts, Assemblies and Equipment. Posts about ESD Handbook ESD TR written by Desco. Alligator clip attached to dissipative mat is not recommended per ESD Handbook ESD TR wrist strap section Wrist Strap Ground Cord: “The.
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Effective ESD control can be a key to improving:. Anybody who handles electrical or electronic parts, assemblies or equipment that are susceptible to damage by electrostatic discharges should take necessary precautions.
Just like viruses or bacteria that can infect the human body, ESD can be a hidden threat unable to be detected by human eyes. The same principles apply to ESD control: If an ionizer is out of balance, instead of neutralizing charges, it will produce primarily positive or negative ions. This results in placing an electrostatic charge on items that are not grounded, potentially discharging and causing ESD damage to nearby sensitive items.
These will alert you when maintenance is required. Maintenance intervals for ionizers vary widely depending on the type of ionization equipment and use environment. Critical clean room use will generally require more frequent attention. It is important to set up a routine schedule for ionizer service.
However, without proper electrical bonds to a grounding system they are not grounded! If you need more information on ESD garments, we recommend having a look at this post. Companies can invest thousands of dollars in purchasing and installing ESD control products but then waste their investment by never checking their ESD items. This results in ESD equipment that is out of specification. Without the tools in place to check their ESD items, companies may have no idea if they are actually working correctly.
ESD products like any other product are subject to wear and tear, and other errors when workstations get moved, ground cords get disconnected…etc. The list goes on.
We provide detailed instructions on how to create a Compliance Verification Plan in this post.
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When used properly, they handhook a Faraday Cage effect which causes charges to be conducted around the outside surface.
Use a system of labels to identify when the bag has gone through five 5 handling cycles. When there are five broken labels, the bag is discarded. Inside an EPA, low charging and static dissipative materials may provide adequate protection.
Outside an EPA, low charging and static discharge shielding materials are recommended. While these materials are not discussed in. Many household cleaners contain silicone or other insulative contaminants which create that lovely shine you get when wiping surfaces in your home.
The problem is that silicone and other chemical contaminates can create an insulative layer which reduces the grounding performance of the mat. What mistakes do you commonly see when walking through an EPA? Let us know what you commonly see in the comments and your solutions for fixing them! While ESD damage can post a danger, there is another risk factor many operators forget: If you have been following along with our blogs, you will be well aware handblok the problems ESD damage can cause.
ESD Handbook ESD TR | Protektive Pak Blog
Moisture, on the other hand, may be a new issue to you. In addition to the bags, Desiccant Packs and Humidity Indicator Cards must be used for proper moisture protection. Most manufacturers of the Moisture Sensitive Devices MSD will tr20.20 how their product should be stored, shipped, ese. It is particularly important to consider what happens to the interior of a package if the environment has high humidity. If the temperature varies across the handbooi point of the established interior environment of the package, condensation may occur.
The interior of a package should either contain desiccant or the air should be evacuated from the package during the sealing process. The package itself should have a low WVTR. Use this desiccant calculator to determine the minimum amounts of desiccant to be used with Moisture Barrier Bags.
Humidity Indicator Cards HICs are printed with moisture sensitive spots which respond to various levels hanxbook humidity with a visible color change from blue to pink. The humidity inside barrier bags can be monitored by the HIC inside. Examining the card when you open the bag will indicate the humidity level the components are experiencing so the user can determine if baking the devices is required.
The Moisture Sensitive Level MSL label tells you how long the devices can stay outside the bag before they should be soldered onto the board. This label is applied to the outside of the bag. With the steps handbool above, your package should now be properly sealed from moisture and protected from ElectroStatic discharge.
Looking for a moisture barrier bag for your application? But what do you do if an item in your EPA is essential to assembly and it cannot be grounded? Let us explain a couple of options which will allow you to use the non-groundable item in question.
In ESD Control, we differentiate items as conductors and insulators. Materials that easily transfer electrons are called conductors.
Insulators are materials that do not easily transfer electrons are non-conductors by definition. Some well-known insulators are common plastics, polystyrene foam, and glass.
Electrostatic charges can effectively be removed from conductive or dissipative conductors by grounding them. To ground all conductors per the first ESD Control principal, all surfaces, products and people are electrically bonded to ground. Bonding means linking or connecting, usually through a resistance of between 1 and 10 megohms. Wrist straps and worksurface mats are some of the most common devices used to remove static charges: If the static charge in question is on something that cannot be grounded, i.
Well, nothing in life is black and white. Most ESD workstations will have some insulators or isolated conductors that cannot be removed or replaced. These should be addressed with ionization. Examples of some common process essential insulators are a PC board substrate, insulative test fixtures and product plastic housings.
An example of isolated conductors are conductive traces or components loaded on a PC board that is not in contact with the ESD worksurface.
An ionizer creates great numbers of positively and negatively charged ions. Fans help the ions flow over the work area. Ionization can neutralize static charges on an insulator in a matter of seconds, thereby reducing their potential to cause ESD damage. For more information on ionizers and how to choose the right type of ionizer for your application, read this post.
The best way to keep electrostatic sensitive devices ESDs from damage is to ground all conductive objects and remove insulators. Insulatorsby definition, are non-conductors and therefore cannot be grounded, but they can be controlled to minimize potential ESD damage.
Do your employees handle ESD-sensitive high-end components that are expensive to replace if they failed? Wrist straps are the most common personnel grounding device and are used to link people to ground. They are required if the operator is sitting.
Components of a Wrist Strap. Dual-Wire Wrist Straps have two conductors compared to single-wire monitors which have only one conductor inside the insulation of the coiled cord. They offer a reduced risk of damaging ESD sensitive devices because if one conductor is severed or damaged, the operator still has a reliable path-to-ground with the second conductor. For that reason, they dual-wire wrist straps are generally used in critical applications. Advantages of using Dual-Wire Wrist Straps: For maximum benefit, dual-wire wrist straps should be used together with dual-wire continuous monitors.
Instead of connecting a coil cord directly to a common grounding point, the operator connects to a continuous monitor. The operator is grounded through the continuous monitor and the operator-to-ground connection is monitored. One of the most common ways to ground people is with a wrist strap. Ensuring that wrist straps are functional and are connected to people and ground is a continuous task. The failure of a wrist strap between checks may expose products to damage from electrostatic charge.
Wrist straps are stressed and flexed to their limits at a workstation. While a wrist strap is being checked, it is not stressed, as it would be under working conditions. When a person is wearing a wrist strap, the monitor observes the resistance of the loop, consisting of a wire, a person, a wristband, and a second wire.
If any part of the loop should open become disconnected or have out of limit resistancethe circuit will go into the alarm state. Pulsed DC signals were developed because of concerns about skin irritation.
However, pulse DC units introduce periods of off time seconds when the system is not being monitored. Dual Polarity Technology provides true continuous monitoring of wrist strap functionality and operator safety according to accepted industry standards. Dual-wire systems are used to create redundancy. In critical applications redundancy is built-in to have a backup if the primary source fails.
With dual-wire wrist straps the redundancy is there as a protection rather than an alternative. If you are monitoring your dual-wire wrist strap and one wire fails, then the unit will alarm. You will still be grounded by the other wire, so there will be a significantly reduced risk of damaging ESD sensitive components if you happen to be handling them when the wrist strap fails. The wrist strap still needs to be replaced immediately.
And there you have it: We get a lot of inquiries regarding wrist straps: If there is something we did not cover in the blog post make sure you ask us in the comments! The most common personnel grounding device is a wrist strap which is used to connect people to ground.
A wrist strap in general is a conductive wristband which provides an electrical connection to skin of an operator and, in turn, is connected to a known ground point at a workbench or a tool.