Category Archives: Article

Pink Vs Black – Use the Right ESD Foam for Your Application

 You might have asked yourself, what is the big difference is between pink ESD foam and black ESD foam? The differences are significant, although one is not necessarily better than the other. Which one you choose depends on what your needs are.

 Pink Static Dissipative FoamPinkFoam_New

  • Static dissipative polyurethane <1011 ohms
  • Antistatic low charging – minimizing electrostatic charge generation
  • Provides protection from physical shock during handling, packaging, shipping, and storage of ESD sensitive devices
  • Ideal for short term use
  • Easy to adapt for custom uses by die-cutting, laminating, etc.PinkFoam_Yellowed_new
  • Non-contaminating, non-corrosive, and non-sloughing
  • Economical

 Usage Consideration

  • Not recommend for lead insertion applications
  • When exposed to the environment, the foam will discolor (turn yellow) over time
  • Will lose electrical properties over time

 

Black Conductive FoamBlackFoam

  • Conductive polyurethane 1 x 103 to < 1 x 105 ohms per ANSI/ESD STM11.11
  • Low density conductive polyurethane foam
  • Permanently conductive; will not lose electrical properties – can be used in applications where permanent ESD properties are required
  • Provides protection from physical shock during handling, packaging, shipping, and storage of ESD sensitive devices
  • Foam will not discolor over time

Usage Consideration

  • Better value for long term applications
  • Not recommended in applications where Static Dissipative properties are required

While each foam is made of the same material (polyurethane), they have very distinct differences. Which one you use will depend on the application of the foam, how long you intend to use the foam,  and even cost considerations.

Learn more about all Protektive Pak foam options. Click Here.

11 Steps to Establishing an ESD Control Plan

1. Define what you are trying to protect.

What is the Human-Body Model (HBM) withstand voltage of the most sensitive item? A prerequisite of ESD control is the accurate and consistent identification of ESD susceptible items. Some companies assume that all electronic components are ESD susceptible. However, others write their ESD control plan based on the device and item susceptibility or withstand voltage of the most sensitive components used in the facility.  A general rule is treat any device or component that is received in ESD packaging as an ESD susceptible item.

2. Become familiar with the industry standards for ESD control.

A complimentary .pdf of ANSI/ESD S20.20-2014 can be downloaded from the ESD Association web site at www.ESDA.org. Also consider purchasing the ESDA’s ESD Handbook ESD TR20.20-2008.

3. Select a grounding / equipotential bonding system.

The 3rd-wire AC electrical equipment ground is the preferred, recommended ground reference.

4. Determine the method of ground for operators (Personnel Grounding).

The two options for grounding an operator are a wrist strap or foot grounders.  Wrist straps must be worn if the operator is seated. If foot grounders are used, an ESD flooring system must be used.  In some cases both wrist strap and foot grounders will be used. The 3rd-wire AC electrical equipment ground is the preferred, recommended ground reference.

5. Establish & Identify EPA(s) – ESD Protected Area(s).

ESD Control Plans must evolve to keep pace with costs, device sensitivities, and the way devices are manufactured. Define the departments and areas to be considered part of the ESD Protected Area.  Consider if customers and/or subcontractors should be included. Implement access control devices, signs, and aisle marking tape to identify and control access to the ESD Protected Area(s).

6. Select ESD control items to be used in the EPA based on your manufacturing process.

Elements that should be considered include: worksurfaces, flooring, seating, ionization, shelving, mobile equipment (carts), and garments.

7. Develop Packaging (Materials Handling & Storage) Plan.

When moving ESD susceptible devices outside an ESD protected area, it is necessary for the product to be packaged in an enclosed ESD Shielding Packaging.

8.  Use proper markings for ESD susceptible items, system or packaging.

From ANSI/ESD S20.20-2014 section 8.5: “the Organization, in developing the ESD Control Program Plan, shall consider the need for marking.”

9. Implement a Compliance Verification Plan.

From ANSI/ESD S20.20-2014 section 7.4: “A Compliance Verification Plan shall be established to ensure the Organization’s fulfillment of the technical requ.rements of the ESD Control Program Plan”.

10. Develop Training Plan.

From ANSI/ESD S20.20-2014 section 7.2: “Initial and recurrent ESD awareness and prevention training shall be provided to all personnel who handle or otherwise come into contact with any ESDS items.”

11.  Make the ESD Control Plan part of your internal quality system requirements.

A written ESD Control Plan provides the “rules and regulations”, the technical requirements for your ESD Control Program. This should be a controlled document, approved by upper management initially and over time when revisions are made. The written plan should include following:

  • Qualified Products List (QPL)A list of EPA ESD control items is used in the ESD control Plan
  • Compliance Verification Plan- Includes periodic checking of EPA ESD control items, and calibration of test equipment per manufacturer and industry recommendations.
  • Training Plan- An ESD Program is only as good as the use of the products by personnel. When personnel understand the concepts of ESD, the importance to the company of the ESD control program, and the proper use of ESD products, they will implement a better ESD control program improving quality, productivity, and reliability.

Do Protektive Pak In-Plant Handlers Need to Have Lids on While ESD Sensitive Items are in Them?

37150CircuitBoard

 Outside the ESD protected area (EPA), the Protektive Pak lids need to be in place to provide the electrostatic discharge shielding ESD control property which is required by the Packaging standard ANSI/ESD S541. Per section 6.2 Outside an EPA “Transportation of sensitive products outside of an EPA shall require packaging that provides: 1. Low charge generation. 2. Dissipative or conductive materials for intimate contact. 3. A structure that provides electrostatic discharge shielding.”

Inside the EPA, it would still be a good idea to have the lid in place, but it is not a requirement. The Protektive Pak impregnated corrugated has a buried shielding layer. In shielding, we utilize the fact that electrostatic charges and discharges take the path of least resistance. The charge will be either positive or negative; otherwise the charge would balance out and be no charge.

Like charges repel and so the electrostatic charge will reside on the outer conductive surface.

Faraday

A Faraday Cage effect can protect ESDS contents in a container with a shielding layer (this is what a shielding bag has). This Faraday Cage effect protects people in real life when a lightning bolt strikes an airplane or automobile with the charge residing on the outer metal fuselage or car body.

The Faraday cage effect causes charges to be conducted around the outside the surface of the conductor. Since like charges repel, charges will rest on the exterior.

To complete the enclosure, make sure to place lids on boxes or containers, and close shielding bags. Packaging with holes, tears, or gaps should not be used as the contents may be able to extend outside the enclosure and lose their shielding as well as mechanical protection.

To ask an ESD question Click Here

To view In-Plant Handlers Click Here

What is the Real Cost of ESD Damage?

 Article written by Terry Welsher, courtesy of InCompliance Magazine 4Cbw

What percentage of electronic failures are latent defects? What’s the cost to industry? According to the ESD Association “It is relatively easy with the proper equipment to confirm that a device has experienced catastrophic failure. Basic performance tests will substantiate device damage. However, latent defects are extremely difficult to prove or detect using current technology, especially after the device is assembled into a finished product.” So there is the view that, by definition, it is impossible to quantify the amount of latent damage. However, for most companies, the cost of customer returns and field service warranty expense greatly exceeds in-house scrap & re-work expense.

Per the ESD Association: “The age of electronics brought with it new problems associated with static electricity and electrostatic discharge. And, as electronic devices became faster and smaller, their sensitivity to ESD increased. Today, ESD impacts productivity and product reliability in virtually every aspect of today’s electronics environment. Industry experts have estimated average product losses due to static to range [up to] 33%. Others estimate the actual cost of ESD damage to the electronics industry as running into the billions of dollars annually.”

Some major companies report that 25% of all identified electronic part failure is due to ESD. As an ESD Control Program improves, a resulting decrease in unidentified field failures and ”no problem found” returns should occur. Reducing latent defect field failures is what allows companies to report return on investments of 10:1 from their ESD Control Programs.

To continue reading The “Real” Cost of ESD Damage Click Here.

Why Use ESD Shielding vs Non-Shielding Containers

ShieldingVsNonShieldingElectroStatic Discharge (ESD) is silent, quick and potentially lethal to electronic parts. When electronic parts are not properly handled during manufacturing, assembly, storage, or shipping, damage from ESD can reach into the millions of dollars each year.

For an ESD control container to be effective against ElectroStatic Discharge, it must possess certain electrical characteristics:

  • Surface resistance <1 x 1011 ohms per ANSI/ESD STM11.11
  • Energy penetration <50 nanoJoules per ANSI/ESD STM11.31

Non-shielding containers might be cheaper, but they are not less costly when it comes to handling ESD sensitive items. Anytime ESD sensitive parts and assemblies are handled, regular containers are not a sound option, even part of the time, as the risk of ESD damage is always lingering. As a result, costs will be incurred, either via ESD damage or as an additional investment in discharge shielding packaging and material handling containers.

The disadvantages of cross-using shielding and non-shielding containers include:

  • Increased cost
  • Risk from ESD damage
  • Handling inconvenience

The cost of a discharge shielding container is far less than the cost associated with damaged parts or extra handling that result with a “less expensive” non-shielding container.

ESD Control – Other Considerations

Application Photo of Surface Resistance Test Kit

OTHER CONSIDERATIONS
Discipline
A significant increase in the discipline of implementing the fundamentals of ESD control noted in ANSI/ESD S20.20 Foreword, calls for:

  • Ground all conductors in the EPA including people
  • Remove all insulators from the EPA or use ionizers for process necessary insulators
  • Package ESD sensitive items going outside the EPA in packaging that provides electrostatic discharge shielding

Insulators
We encourage developing a hatred for insulators. The alternatives are:

    Remove the insulative item from the EPA

  • Substitute the item with an ESD protective version (such as tape, document holders, material handling containers, plastic bottles, etc.)
  • Periodically treat insulative surface with a topical antistat
  • Neutralize electrostatic charges using ionization

Other ESD Control Items
Other EPA ESD control items to add to the ESD control program might include shelving, mobile equipment (carts), gloves, and/or seating.

Improve Compliance Verification Plan

  • Consider greater frequency of internal audits per ESD TR53
  • Use of computer data collection system for wrist straps and footwear testing, continuous monitors, and ionizers
  • Use of ground continuous monitors for worksurfaces and other ESD elements
  • Test ionizers more frequently, consider self monitoring ionizers, consider computer based data collection
  • Increased testing using static field meter to verify that automated processes (like auto insertion, tape and reel, etc) are not generating charges above acceptable limits.

Application Photo of Volt Meter and Software in Factory STM97.2 Testing Voltage Charge on Person (Photograph courtesy of TREK, INC.)

Improve Training

  • ESD awareness training for all in the EPA or who may come into the EPA including suppliers
  • Testing to verify comprehension and training adequacy
  • Training on the proper use of test equipment
  • Training on proper compliance verification test procedures

Application Photo CD-ROM ESD Training

Conclusion
Just to maintain a company’s current level of quality and reliability may require a substantial improvement in a company’s ESD control program. Now is the time for improvement as ESD sensitivity withstand voltages continue to get lower and companies may soon be handling class 0A HBM items. To combat HBM failures improved personnel grounding is required. For example, heel grounders should be replaced with full coverage foot grounders. However, most failures are CDM. To combat CDM failures, ionization should be added or improved, and conductive surfaces should be covered with dissipative material. In general, disciple should be enhanced implementing ESD control fundamentals, compliance verification testing should be increased, and training should be improved.

From published article “Now is the Time for ESD Control Programs to be Improved” by Fred Tenzer and Gene Felder. See full article at InCompliance Magazine- September 2012

Tips for Addressing Charged Device Model Failures


CHARGED DEVICE MODEL

It may seem to some that CDM has newly arrived as a problem for ESD control programs. However, the ESD Association first published ANSI/ESD STM5.3.1 in 1999 – ESD Association Standard for Electrostatic Discharge Sensitivity Testing – Charged Device Model (CDM) – Component Level. Basically, CDM testing has to do with “testing, evaluating and classifying the electrostatic discharge (ESD) sensitivity of components to the defined charged device model (CDM)” … “to allow for accurate comparisons of component CDM ESD sensitivity levels.”

JESD22-C101C Field-Induced Charged-Device Model Test Method for Electrostatic-Discharge-Withstand Thresholds of Microelectronic Components Table 3
Devices shall be classified as follows:
CLASS I <200 volts
CLASS II 200 to <500 volts
CLASS III 500 to 1000 volts
CLASS IV >1000 volts

The importance of CDM came about primarily because of the increased use of automated component handling systems. The Foreword of ANSI/ESD STM5.3.1 states “In the CDM a component itself becomes charged (e.g., by sliding on a surface (tribocharging) or by electric field induction) and is rapidly discharged (by an ESD event) as it closely approaches a conductive object.”

In November 2002, Roger Peirce published an article entitled “The Most Common Causes of ESD Damage”. There were actually 23 causes. As the founder and president of ESD Technical Services, Roger had investigated hundreds of companies for over eight years. All 23 causes were CDM failure modes. So CDM is really not so new, it has just received a lot of attention in the last few years.


TACKLING CDM

So, what are the things companies should look at to improve their ESD control program regarding CDM? It would seem to be easy: don’t slide ESDS devices and assemblies unless grounded at all times, keep insulators at least 12” away from ESDS, and don’t allow ESDS items to make contact with a conductive surface. Seems simple, but in actual application . . . not so easy.

If the ESD control program has not used ionization that should be considered. If the ESDS items becomes charged, ionization will help neutralize the charge. The primary function of ionizers with regard to ESDS items are:

  • To remove / neutralize charges from process necessary insulators, which can charge ESDS items, thus creating the potential for a damaging CDM event
  • Remember that the PCB substrate is a process necessary insulator and can become charged during automated handling processes
  • To remove / neutralize charges from a charged, isolated/floating conductor, which, when grounded can result in a potentially damaging CDM event
  • Remember that during automated handling processes, the ESDS devices on the PCB are isolated or floating conductors

Application Photo Overhead Ionizer

The ESD Standards Committee has a Working Group (WG-17) which is currently involved with developing a Standard for Process Assessment to help the electronics community assess their manufacturing and handling processes to determine what levels of devices their process can handle. Once one fully understands where their process is with regards to ESDS devices and assemblies, they will have a clearer picture on what actions need to be taken to further improve the ESD Control Program.

If ionizers are already in use, the company should consider reducing the ionizer offset voltage limit of ±50 volts (the required limit in ANSI/ESD S20.20) to ±25 volts and maybe less, depending on the application and device sensitivity. Discharge times are user defined and should be considered for reducing the time required to neutralize a ± 1,000 volt charge to ± 100 volts.

The required limit for worksurfaces per ANSI/ESD S20.20 is less than 1 x 10^9 ohms with no lower limit. Most companies handling electronics should be following the recommendation of Worksurface standard ANSI/ESD S4.1 that the lower limit be 1 x 10^6 ohms. To combat CDM failures, all surfaces that might come into contact with ESDS items should be dissipative at the 1 x 10^6 to less than 1 x 10^9 ohms range used for worksurfaces where possible. Items such as Static Shielding bags will have a higher resistance on the interior & exterior surfaces, but it still must be less than 1 x 10^11 ohms.

Application Photo Statfree Worksurface Mat

From published article “Now is the Time for ESD Control Programs to be Improved” by Fred Tenzer and Gene Felder. See full article at InCompliance Magazine- September 2012

What’s Happening to Electronics Device ESD Sensitivity

Factory ESD control is expected to play an ever-increasing critical role as the industry is flooded with even more HBM (Human Body Model) and CDM (Charged Device Model) sensitive
designs.

ElectroStatic Discharge (ESD) is the hidden enemy within your factory. You cannot feel or see most ESD events but they can cause electronic components to fail or cause mysterious and annoying problems. There are two types of ESD damage: 1) catastrophic failures, and 2) latent defects. By definition, normal quality control inspections are able to identify catastrophic failures, but are not able to detect latent defects.

In general, the ESD susceptibility of modern electronics are more sensitive to ElectroStatic Discharge; that is the withstand voltages are lower. This is due to the drive for miniaturization and with electronic devices operating faster. Thus the semiconductor circuitry is getting smaller. What’s happening currently? The width of electronic device structures continues to get smaller. Intel began selling its 32nm processors in 2010 that would be 0.032 micrometer equal to 0.000032 millimeter or 0.00000128 inch.

See www.ESDA.org, the ESD Association’s latest White Paper “Electrostatic Discharge (ESD) Technology Roadmap” Revised April 2010” forecasts increased ESD sensitivities continuing the recent “trend, the ICs became even more sensitive to ESD events in the years between 2005 and 2009. Therefore, the prevailing trend is circuit performance at the expense of ESD protection levels.” The White Paper’s conclusions include:

  • With devices becoming more sensitive through 2010-2015 and beyond, it is imperative that companies begin to scrutinize the ESD capabilities of their handling processes. Factory ESD control is expected to play an ever-increasing critical role as the industry is flooded with even more HBM (Human Body Model) and CDM (Charged Device Model) sensitive designs. For people handling ESD sensitive devices, personnel grounding systems must be designed to limit body voltages to less than 100 volts.
  • To protect against metal-to-device discharges, all conductive elements that contact ESD sensitive devices must be grounded.
  • To limit the possibilities of a field induced CDM ESD event, users of ESD sensitive devices should ensure that the maximum voltage induced on their devices is kept below 50 volts.
  • To limit CDM ESD events, device pins should be contacted with static-dissipative material instead of metal wherever possible.

See May 2010 article by Dr. Terry L. Welsher The “Real” Cost of ESD Damage which includes “Recent data and experience reported by several companies and laboratories now suggest that many failures previously classified as EOS [Electrical Overstress] may instead be the result of ESD failures due to Charged Board Events (CBE). Some companies have estimated that about 50% of failures originally designated as EOS were actually CBE or CDE [Charged Device Events].”

ANSI/ESD S20.20, the ESD Association document covering the development of an ESD control program, lists numerous ESD Protected Area (EPA) ESD control items. Each company can pick and choose which ones are appropriate for their program. The selection of specific ESD control procedures or materials is at the option of the ESD Control Program Plan preparer and should be based on risk assessment and the established electrostatic discharge sensitivities of parts, assemblies, and equipment.” [ANSI/ESD S20.20-2007 Annex B] “An EPA [ESD protected area] shall be established wherever ESDS [ESD Sensitive] products are handled. However, there are many different ways to establish ESD controls within an EPA. Table 3 lists some optional ESD control items which can be used to control static electricity. [ANSI/ESD S20.20-2007 section 8.3 ESD Protected Areas (EPAs)]

There are companies with good ESD control programs who are pleased with their quality and reliability results. But to maintain that level, they would be wise to consider ESD control program improvements. Now might be a good time to do that.

From published article “Now is the Time for ESD Control Programs to be Improved” by Fred Tenzer and Gene Felder. See full article at InCompliance Magazine– September 2012

Images of ESD Damage

Seeing ElectroStatic Discharge (ESD) damage is basically impossible. Damage to semiconductor device structure is NOT visible at ordinary magnifications of an optical microscope. If the microscope is capable of 1000X-1500X magnifications, you just might be able to “see” something. The method used, only occasionally as there is considerable expense, is by delayering and etch enhancement producing high magnification photographs using a scanning electron micrograph (SEM). See Images of ESD Damage, photos of Human Body Model (HBM) ESD damage provided by Hi-Rel Laboratories, Inc. at 6116 N Freya, Spokane, Washington 99217 (509-325-5800 or www.hrlabs.com). Used with their permission.

ElectroStatic Discharge (ESD) Person Can Feel

It typically takes a ESD discharge greater than 2,000 or 3,000 volts for a person to feel the “zap”.

There is no exact voltage number where a person starts to feel a discharge. The ESD Association addresses this topic three times in the ESD Handbook ESD TR20.20 using these phrases:

  • “greater than 2000 volts”
  • “about 3,000 volts”
  • “exceed 3,000 volts”

The sensitivity of people is different and measuring the voltage is imprecise, so neither 2,000 nor 3,000 is to be an exact number.

Per ESD Handbook ESD TR20.20 Wrist Strap section 5.3.2.1 “Static electricity is a natural phenomenon that occurs in all climates and at all levels of relative humidity year round. Most people cannot feel an electrostatic discharge unless the static voltage is greater than 2000 volts.”

Per ESD Handbook ESD TR20.20 section 2.3 Nature of Static Electricity “The quantity, charge, is difficult for most people to visualize without some reference. As an example, an average person has a capacitance of about 100 picofarads (pF) and can feel a static discharge at their fingertips when the potential difference between their body and a grounded conductive object is about 3,000 volts (3 kV).”

Per ESD Handbook ESD TR20.20 ionizer section 5.3.6.5.3.3 Discharge Time and Product Sensitivity “Most personnel will not notice static discharges from the human body until they exceed 3,000 volts.”

The point, of course, is just because you cannot see or feel an ESD event, it does mean that ESD events are not occurring. Human beings are insensitive unless the ESD is several thousand volts. Many electronic components can be damaged by much smaller discharges.