Static Control Tips and Tricks Archives

ST 925 SMT Rework System–Three favorites combined into one nice savings


Save a few steps--and some money--with the Pace 925 SMT Rework System Pace has introduced a new low-cost “combination” system ideal for surface mount technology (SMT) rework. It’s worth adding up the savings by comparing the a la carte prices Read more

Metcal’s CV-5200 Connection Validation Soldering Station Changes Everything


You may or may not have heard about Metcal’s new soldering station, the CV-5200. The evolutionary tool removes much of the reliance on visual inspection of hand-soldered joints and adds a second, more technology-driven method for validating a successful Read more

Seven Things to Know About Qualifying Your Product to a U.S. Military Specification (MIL-SPEC)


Qualifying the SCS 81705 Series anti-static shield bags to military standards There are a few, sometimes complicated steps to go through before your product can qualify for a particular military specification. SCS recently introduced their new 81705 Series static shield Read more

Dry Air Static Control and Ionizers

Posted on by Barb N. in ESD News, Static Control Tips and Tricks Leave a comment

Dry air and ESD control

The specifications and devices being assembled determine the recommended humidity range for a manufacturing facility. When the air is dry, static control becomes much more challenging. Although ESD events may be reduced by increasing the humidity, unfortunately that same humidity may cause a reduction in the quality of moisture-sensitive devices because of corrosion, soldering defects and the popcorn effect.

Ionizer choices for reducing ESD

Although ionizers cannot replace grounding or shielding of ESD work surfaces, ionization can lessen ESD events in areas where dry air is normal.  Desco has number of ionization products available through All-Spec.

  1. Benchtop and overhead Ionizers – work surface ionizers create positively and negatively charged ions that are moved to the controlled area with fan-driven airflow.
  2. Point-of-use air ionizers – use compressed gas to combat electrostatic attraction neutralizing charges on particles causing contamination or visual defects on products.
  3. Laminar flow ionization bars – used with laminar flow hoods, controlled chambers and other contained applications.
  4. Room Ionization – reduces electrostatic discharge (ESD) and electrostatic attraction (ESA) in cleanroom environments.

For more information, consult the ESDA’s TR20.20-2008 RH information. Below find some of the significant statements about dry air and static electricity.

dry-air-popcorn-effectESD Handbook ESD TR20.20-2008 Section 2.3 Nature of Static Electricity:

  • Static electricity in the form of static cling and static shocks are more prevalent when the air is dry.
  • Heating interior air in the winter months dries out the already dry air in the higher latitudes.
  • Static charge accumulation is easier on dry materials since moisture on surfaces tends to allow charges to slowly dissipate or recombine.
  • Humidity control alone cannot provide static control since static charges are developed even at relative humidity levels of 90% and greater.
  • For most situations, 30 to 70% RH is considered the appropriate range.
  • Special areas, such as wafer fabrication, may require lower humidity control for processes that are affected by moisture (e.g., photoresist application).
  • Soldering is known to be affected by high relative humidity conditions (>70%).
  • Ionization is an important consideration in areas with low ambient humidity to aid in reducing charge accumulation levels and provide neutralization of charges after they are developed but before they can cause difficulties.

 

desco-point-of-use-air-ionizerESD Handbook ESD TR20.20-2008 Section 5.3.16 Humidity:

  • Humidity is beneficial in all ESD control program plans.
  • Contact and separation of dry materials generates greater electrostatic charges than moist materials because moisture provides conductivity that helps to dissipate charge.
  • ESD effects are most noticeable in the winter since heating systems reduce building environment moisture.
  • Geographic location (desert vs. coastland) is a major contributor to ambient conditions inside buildings.
  • Any circumstance that results in a low relative humidity will permit a greater accumulation of electrostatic charges.
  • Relative humidity above 30% in ESD protective areas is desirable as long as other adverse conditions are not created as a result of humidity levels.
  • In general, an upper limit of 70% is desirable to prevent corrosive effects on the metal portions of electronic devices and assemblies.
  • Dry air increases the tendency to generate electrostatic charges on dry materials and performance of many ESD protective materials degrade.
  • When exposed to low humidity conditions, some ESD protective materials become totally ineffective or become sources of electrostatic charges.
  • Evaluation of ESD control materials should include performance testing in controlled environments at the lowest expected operating relative humidity level.
  • Manufacturers of ESD protective materials should be able to provide performance data in regards to relative humidity.
  • Materials should be tested in moderate humidity conditions as well to ensure they do not become “too conductive” and present a potential safety hazard to personnel working with substantial voltages. See the Personnel Safety section of this handbook for further guidance in this area.

 

Humidity control alternatives

 Humidity control in factories or physically large areas or buildings can be difficult and expensive. In smaller rooms or areas, it may be possible to use portable humidifiers to raise the immediate area humidity. However, in many large facilities and factories the environmental systems need to include steam generation and monitoring equipment to control humidity. This type of equipment is expensive to install and purchase especially in pre-existing facilities. To reduce the total cost impact, companies should consider the need for humidification equipment when planning new facility construction.


The Benefits of ESD-Safe Turntables -Take One for a Spin

Posted on by Barb N. in Cleanroom, ESD News, Product Reviews, Static Control Tips and Tricks, Technical Articles Leave a comment

Remember the lazy Susan?

imagesOnce a staple on every dining room table where with a spin of a wooden disc your salt and pepper shakers suddenly appeared in front of you. The same idea works for an ESD-safe turntable, however this disc does much more than turn.

Just like the revolving server, the turntable rotates to make working on large products and assemblies easier. With an ESD-safe turntable you avoid lifting heavy objects and–potential back injuries. With just a turn of the wheel you can access your next work area with ease—no lifting, lugging or jostling into place. And of course, the turntable eliminates electrostatic build-up.

The devices can be used on grounded or ungrounded surfaces, however on ungrounded surfaces the turntable must be grounded. The sizes range from 12” to 20” and come in different shapes depending on your application and preference.

esd-turntable

ESD-Safe Turntable – Not for use with food. Great for heavy objects.

The ESD-safe turntable can be an invaluable tool in the electronics industry and has become a staple in its own right at many workstations. See a choice of ESD-safe turntables at All-Spec including these brands – Protektive Pak, Fancort, Sovella and Desco.

Summary –

  • Keeps heavy objects grounded and shielded from static
  • Eliminates heavy lifting or transport
  • Protects workers, products and components
  • Useful all kinds of heavy assembly, rework or maintenance jobs
  • Removes charges on contact with grounded ESD surfaces

 

 

SEE HOW IT WORKS – Protektive Pak ESD Turntable


Putting Your Components to the ESD Test

Posted on by Barb N. in ESD News, ESD Testing, Static Control Tips and Tricks Leave a comment

Testing ESD Sensitivity 

Testing the sensitivity of components to ESD can be done in a couple of different ways. Either way, you’re determining what it takes to make a device fail when subjected to an electrostatic discharge (ESD). The two primary models for ESD testing include Human Body Model (HBM) and Charged Device Model (CDM) testing.

The models can simulate events; though they can’t completely mimic the entire range of potential ESD events. These two tests, HBM and CDM however have proven to be successful at reproducing more than 99% of ESD field failure signatures. Through these tests industries can –

  • Create and quantify suitable on-chip protection
  • Make comparisons between devices
  • Form a classification system for ESD sensitivity to help ESD design and monitoring requirements of manufacturing and assembly settings
  • Access documented test procedures to substantiate reliable and repeatable results

Human Body Model (HBM) Testing

Kid with hair standing up ESD

Human Body Model (HBM) testing

It doesn’t take much to cause a discharge. Walk across the floor in your socks and you’ you add an electrostatic charge to your body. After doing so, if you were to touch your finger to a lead on a ESDS device or assembly, the body could discharge and possibly cause damage to the device.

The oldest and most common form of testing to classify ESD sensitivity–using an ESD simulator with a special output circuit called the Human Body Model (HBM). The device is placed in a test system and contact is made through a relay matrix and the device is zapped with ESDs.

The device is considered to have failed if it doesn’t meet the datasheet parameters using parametric and functional testing. Failures usually include junction damage, metal penetration, melting of metal layers, contact spiking and damaged gate oxides.

Charged Device Model (CDM) Testing

charged device model testing

Charged Device Model (CDM) testing

A charge can also come from an ESDS device and cause an ESD event. For instance, if a device slides down a feeder in an automated assembler, the device can become charged. If it were to touch the insertion head or another conductive device, a quick discharge may take place. This represents a Charged Device Model (CDM) event and is potentially more destructive than an HBM event. Damage can take place in as little as a nanosecond.

This type of event generally happens in automated-manufacturing environments where machines may always stay turned on and cause electronic integrated circuits (ICs) to become charged. If the part touches a grounded conductor, the built-up storage of energy discharges. CDM discharge depends mostly on the parasitic parameters of the discharge as well as the size and type of component package.

To test, the device is placed on a field plate with the leads pointing up; then the device is charged and discharged.

 

All-Spec EOS/ESD Audit Kit

All-Spec EOS/ESD Audit Kit

All-Spec carries a large selection of quality ESD testing and measurement equipment such as EOS/ESD audit kits, electrostatic field meters and static locators; surface resistivity meters; and ESD event, EMI field and RF signal detectors.

All-Spec also carries a comprehensive range of ESD-safe, static control grounding supplies and partners with industry leaders like  SCS, Desco, Simco-Ion and more to offer the best static control products on the market.

 


ESD–Smaller Parts, Bigger Problems

Posted on by Barb N. in ESD News, Static Control Tips and Tricks, Technical Articles Leave a comment

ESD Sparks Conversation

It’s no shock that smaller electronic parts have been causing bigger ESD (electrostatic dissipation) problems–serious problems that cause component damage and money. How much damage depends on the sensitivity or susceptibility of the device.

Thankfully you can put controls in place to significantly reduce ESD incidents. Preplanning, understanding causes and solutions, and wearing special fabrics and components will help.

Preplanning

  1. Design products and assemblies to be as protected as practical from ESD damage
  2. Decide how much of the environment needs to be controlled
  3. Identify the areas needing protection and ESD sensitive parts
  4. Define the electrostatic protected areas (EPAs)
  5. Define the areas where ESD sensitive parts (ESDs) will be handled
  6. Eliminate static generating processes to reduce electrostatic charge generation; keep processes and materials at the same electrostatic potential; provide appropriate ground paths to minimize charge generation and accumulation
  7. Use grounding, ionization, and conductive and dissipative static control materials to dissipate and neutralize
  8. Use grounding, ionization, and conductive and dissipative static control materials to dissipate and neutralize
  9. Protect products from ESD with proper grounding or shunting, static control packaging and material handling products

Areas needing ESD protection

Causes and effective solutions

ESD is a tiny version of lightning. As the current dissipates through an object, it’s seeking a low impedance path to ground to equalize potentials. In most cases, ESD currents will travel to ground via the metal chassis frame of a device. However, it’s well known that current will travel on every available path.

Table showing esd causes and solutions

Control the area

The first step is to ground all components of the workstation and the personnel (work surfaces, equipment, etc.) to the same electrical ground point, called the “common point ground” i.e., system or method for connecting two or more grounding conductors to the same electrical potential.

All-Spec carries all of the products listed below to help you control your environment and keep it safe from ESD.

ESD control materials

 


Anti-Static Mats: How to Protect Your Bottom Line from Catastrophe

Posted on by Kathy S. in Static Control Tips and Tricks Leave a comment

Anti-Static Mats--How to Protect Your Bottom Line from CatastropheWhen an ESD catastrophe strikes your workplace, the ensuing damage can be—well, catastrophic. But, it can also be latent.  Do you know the difference? And, what can you do to help prevent damage of any kind?

Static is generated when two materials come into contact and are separated, causing electrical particles to be transferred from one object to the other. ESD or an electrostatic discharge takes place when the charged object comes into contact with a conductor, and the static escapes.

What does that mean for your sensitive devices? If they aren’t protected, they could experience either catastrophic damage or latent damage. It’s catastrophic if your components are immediately destroyed and latent if the damage is delayed. Either way can be catastrophic to your bottom line.

So, how do you combat ESD? While you can’t eliminate static generation or discharge, you can neutralize any charges as they occur with a properly grounded anti-static mat that allows the charges to move across its surface slowly.

Anti-static mats come in a variety of styles for the benchtop and the floor—from the laboratory to the cleanroom. Don’t know which kind is best for your environment? All-Spec’s mat selection guides take the guesswork out of the process, so you can escape any and all of ESD’s catastrophes.


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