The Importance of Testing & Monitoring Your ESD Grounding Devices – Guest Blog

by Craig Zander, Transforming Technologies

In Craig’s debut Guest Blog for Q Source, he explains the importance of testing and monitoring of ESD grounding devices.

Transforming Technologies PDT 800K Test Station

The first line of defense for protecting electronic devices and assemblies from damage due to Electrostatic Discharge (ESD) is to properly ground all personnel that come in contact with the product. When a person is effectively grounded, all of the voltage that accumulates on their body when moving rapidly travels to ground before it can affect the product.

The most common and reliable method for grounding operators is the wrist strap and coil cord combination. The conductive materials inside the wrist band contact the skin and transfer the voltage from the operator through the cord and to ground. When worn correctly, and tested or monitored, wrist straps are the preferred method for grounding people.

When grounding a person through a wrist strap, ANSI/ESD S20.20 requires the resistance of the person to equipment ground to be less than 3.5 x 107 ohm (35 meg ohm). Typically, the resistance to ground of a person properly connected with a wrist strap is just over 1 meg ohm (the value of the resistor in the cord assembly).

Wrist strap and coil cord assemblies need to be tested or monitored regularly. Some companies chose to test the wrist strap system one or more times per day at central testing stations (for example, the PDT 800K Test Station). Other companies opt to continuously monitor (using a device such as the CM1602 Constant Monitor) the wrist strap connection so that product is not handled if the grounding system fails.
 

Transforming Technologies CM1602 Constant Monitor

There are situations, however, when being connected to a ground jack via a cord is not conducive to efficient or even safe operation. Operations that involve frequent transportation of product within the facility, as well as operations that involve machinery, present a challenge to the wrist strap and coil cord grounding method. In these cases, factories may use a combination of conductive flooring and foot grounders to effectively ground the operator.

The requirements for grounding a person through flooring and footwear have changed in the ANSI/ESD S20.20 2014 Standard. Previous versions of ANSI/ESD S20.20 provided you with two options. If the resistance from the person through the footwear, through the floor and to ground was less than 35 megohm, no further testing was necessary. If the resistance was greater than 35 megohm, you could still meet the requirements of the standard if the resistance was less than 1.0 x 109 ohms and you can demonstrate that the operators generate less than 100 volts. The latest version of S20.20 (ANSI/ESD S20.20-2014) requires the resistance test and the walking voltage test for qualifying flooring and footwear materials together. While many flooring and footwear options may pass the resistance test, it has been discovered that some combinations of floor materials and foot grounding materials do not work well together.

To test the walking voltage generation of flooring and footwear systems you use ANSI/ESD STM 97.2 Floor Materials and Footwear - Voltage Measurement in Combination with a Person. This test involves recording the voltage of a person while they perform a repetitive walking pattern. To record the voltage you can use a charge plate monitor with data recording capability, or a similar instrument with the same specifications listed in the test method.

Body voltage measurement test set-up.
The new software “Digilloscope”
can mark the five highest
peaks automatically and calculate
the average value.

Transforming Technologies developed the Warmbier WT5000 Walking Test Kit to meet the needs of the ANSI/ESD STM 97.2 test. The WT5000 is a battery-operated instrument that is easily transported to various areas of the factory floor. The system includes the trademarked data acquisition and analysis software “Digilloscope for Windows™.”

The WT5000 records the voltage on the operator while they are performing the walking steps called out in the standard. Once several repetitions of the pattern are complete, the software will provide the peak voltage and average value. The data is used to confirm compliance to standards and to determine the lowest possible voltage device (Human Body Model Discharge Threshold) that can be handled in the facility.

Thanks for that very important information about ESD control and testing, Craig. We look forward to future Guest Blogs to learn from your expertise.

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Olympic Storage Company Shelving Products Added to QSource.com

We’ve recently added another new line of quality products to QSource.com. Come check out Olympic Storage Company’s selection of shelving and shelving-related products and accessories.

QSource.com’s Olympic Storage offerings include carts, security enclosure kits, wire shelves, dunnage racks, and accessories like posts, casters, and dividers. Olympic products are used in a variety of industries including commercial, healthcare, food service, and industrial.

Visit our Olympic Storage Company page to make a purchase. For additional information or questions about Olympic Storage, you may contact us by phone (800-966-6020), email, or via our Web site.

For additional Q Source product information, reviews, how-to articles, and special offers please subscribe to our email newsletter.

QSource.com Adds Keystone Safety & TechNiGlove International Lines for Cleanroom/Controlled Environments

QSource.com recently added new product lines from Keystone Safety and TechNiGlove International. These products are focused on cleanroom, contamination control, and related environments.

KEYSTONE SAFETY

Keystone Safety, a prominent manufacturer since 1925, produces durable, cost-effective products for a variety of uses such as food processing, cleanrooms, contamination control, etc. Their core items include aprons/sleeves, caps/hair nets, coveralls, lab coats & shoe covers. Since their revolutionary Adjustable Cap debuted in 1925, Keystone has grown their offerings to more than 100 different products.

TECHNIGLOVE INTERNATIONAL

TechNiGlove International, founded in 1998, is a leading manufacturer of disposable gloves for use in contamination-controlled environments including cleanrooms, sterile non-medical environments, pharmaceutical, and industrial settings. TechNiGlove is the innovator behind color-coded nitrile gloves, the TechNiPack (the 100% plastic dispenser box), and the refillable TechNiTote (large-capacity, refillable). TechNiGlove products are available in nitrile, sterile nitrile, and latex.

Visit our Keystone Safety and TechNiGlove International pages to place your order. For additional information or questions about these leading brands, you may contact us by phone (800-966-6020), email, or via our Web site.

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Flux Cleaning Myths: The Basics - Guest Blog

by Steve Allen, VP Marketing and Innovation, ACL Staticide
 
In Steve’s latest Guest Blog he focuses on a few myths about flux cleaning

There are many myths and misunderstandings about cleaning solder flux from printed circuit boards. Let’s address some of those primary PCB cleaning & preparation myths and concerns for a variety of rework and repair operations.

To begin, we clean and remove most flux residues to prevent metal oxidation and generally poor electronic circuit connections.

Technologists and technicians alike are often advised to clean boards post-soldering processes with isopropyl alcohol (i.e., IPA). But there are proven chemical reasons for not using a hygroscopic solvent like IPA (hygroscopic solvents draw moisture from the air to themselves as an equilibrium mechanism) for basic board cleaning and further process preparation.

In most instances, IPA is too aggressive for most plastics and can intrude into parts and spaces creating undesirable effects. IPA is known to dissolve polystyrene and other types of plastic capacitors. By dissolving various materials, a potential low-ohm and conductive film is spread over the surface of the PCB while the flux itself (typically a very high solids material) is left untouched in a host of board surface areas, and in particular, at the solder joints. Leftover flux materials can be detrimentally conductive in many instances.

A LOOK AT FLUX MATERIALS

Rosin-based flux is generally not conductive unless it is baked on at extremely high temperatures (caramel or black in color). Generally, no-clean flux is just that. It does not always require cleaning and you may leave it on. Many low-solids flux materials, when applied under a correctly controlled process, will completely evaporate with time. Most water-soluble fluxes need to be removed simply because they leave behind a soap-scum-like residue, which is generally conductive.

Additionally, there are some very aggressive fluxes like RA that must be removed as they contain very acidic substances. RMA is the most prevalent rosin flux (RMA rosin = mildly activated and RA rosin = less activated). It is actually not the rosin that performs the flux activity, but another substance in the flux compound, which promotes spreading and adhesion. The basic rosin material is simply a carrying vessel for the active flux ingredient.

FLUX WORKS ON TWO FRONTS

When activated (and temperature controls this; most fluxes kick in around 100° C or 212° F), flux is a very reactive element that wants to bind with oxygen molecules. It is so reactive it can strip oxygen molecules that have already bonded with copper. So, it converts copper oxide back into basic copper. The second thing flux does is lower the surface tension of the solder. This lets the solder flow over the soldered surface, spread, and adhere.

Under a correctly controlled process, the flux is given some time to activate and do its work before solder is applied. Wave solder machines apply warm flux to the board first, then let it soak for a few seconds as the conveyor moves over a warming plate, and finally the flux is fully activated. The board then passes through the solder wave where the flux totally evaporates and essential leaves behind a clean board.

Solder paste works in a similar way. When conducting reflow processes, you have a ramp up to flux activation, a hold phase to let the flux do its work and evaporate, and finally, a ramp up to liquid phase where the solder melts and flows on the remaining flux. In theory, if reflow operations are done correctly, there should be minimal flux residue and board washing is simple or may not be required at all.

Boards that have been reworked (e.g., manually touching one individual component) will have residue and require washing with flux removers. The flux in solder wire is a different composition than the flux found in pens or liquid form. The flux in solder wire is dry powder and is more aggressive than paste as it has a shorter time to do its work.

Plus, there are specially formulated fluxes like the gel fluxes or tacky fluxes. These are formulated for the rework process, and the practice is to use a lot of it; so much of it that there is excessive residue and you need to remove it. The same goes for pen fluxes, which are also for rework. Most fluxes for wave soldering come in a 55-gallon drum, which is not something most end-users keep on the workbench!

In general, when performing handwork, you will need to clean the board unless no-clean is used, when doing reflow or wave soldering. If aesthetics are key, it’s important to clean. And, every kind of flux has its own specific flux remover. Some flux removers are broad spectrum. Most flux removers require flood cleaning; you need to use a substantial amount to effectively clean and wash a board. Simply squirting a tiny bit on does not work. It just leaves goop all over the board like a sticky film. You need to flood it on, let it soak for a few seconds, and in many cases, scrub with a brush. Then repeat the spray process to wash the “spent” material off the board. As a final process, let the board drip out and spray once more. If needed, apply warm air to dry. Never blow air using your mouth (human breath actually contains saliva, which is acidic). As the flux evaporates, it cools down the board which pulls moisture out of the air. Always use your reflow hot air gun for any type of final finishing and drying.

When it comes to technical cleaning, ACL Staticide manufactures top-quality rework and repair cleaning products and compliments, and QSource.com is your resource for all of them.

Thank you Steve, for that informative Guest Blog and for clearing up those flux cleaning myths. We look forward to your next blog submission.

For information about ACL Staticide and their related products, please visit our ACL Staticide Department at QSource.com. You may also contact us via email or phone at 800-966-6020 and one of our associates will be happy to assist you.

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Q Source Adds Innovative Berkshire Line for Cleanroom Apps

QSource.com has added a new resource for your cleanroom/critical environment needs: Introducing Berkshire Corporation cleanroom and contamination control products. Hundreds of Berkshire solutions for critical surfaces and controlled environment applications are now available at discounted prices.

Based in Great Barrington, MA, Berkshire has been a global innovator in manufacturing cleanroom/contamination control products since the mid-1960s. Berkshire products are used in the following industries:

• Aerospace & Defense – Manufactured to meet the demanding surface prep and cleaning standards set by the government, Berkshire low-linting disposables ensure compliance for everything from equipment and parts manufacturing to everyday maintenance and repair
• Automotive – Berkshire's low-linting dry and pre-wetted critically clean products enable clean, smooth results throughout the surface preparation and refinishing process
• Food & Beverage – Utilize Berkshire's patented, low-linting contamination control products to meet quality goals, comply with rigorous government regulations, and improve HACCP (hazard analysis and critical control points) and SSOPs (sanitation standard operating procedures)
• Healthcare – Protect patients, workers/staff, and visitors with Berkshire's economical, low linting cleanroom products, which address critical contamination control concerns
• Medical Device – Berkshire's low-linting surface cleaning and preparation disposables support a wide range of critical biomedical device manufacturing methods, and support the production of catheters, contact lenses, heart valves, pacemakers, and more
• Microelectronics – Facilitate the highest contamination-control levels for precision electronics, printed circuitry, microelectronic and semiconductor manufacturing applications with Berkshire's ultra-clean low-lint, low-ion products
• Optics – Berkshire's non-abrasive, soft wipers protect scratch-sensitive surfaces like lenses, mirrors, and other optical components in critical optics and photonics manufacturing and maintenance
• Pharmaceutical – Need to observe strict regulations? Berkshire's critical contamination control products help you adhere to cGMP practices and lot traceability in standardized and government-regulated industries
• Print – Use Berkshire's low-lint contamination-control products for low-cost/high-quality cleaning of industrial inkjet printers, typesetting machines, and imaging equipment
• University/Research – For research/laboratory settings focused on topics like nanotechnology, engineering, physics, astronomy, and bioprocessing, use Berkshire's contamination control products and low-linting surface cleaning supplies

ENGINEERED CLEAN

QSource.com now offers all of the popular Berkshire series (e.g., CapSure, Choice, Labx, SatPax, ValuSeal, and others). These include Berkshire's wide variety of cleanroom/contamination control products in the following categories:

• Dry Wipers – Low-linting, low-shedding dry cleanroom wipes for contamination control and surface cleaning
• Pre-Wetted Wipers – Sterile and non-sterile pre-wetted wipes saturated with various alcohol and ethanol formulas
• Swabs – Berkshire’s Lab-Tips® swabs for precision cleaning, surface sampling, validation procedures, and the application of lubricants or other liquids
• Cleanroom Paper – Low-linting cleanroom bond paper reams, notebooks, and documentation/writing systems
• Glove Liners – Soft, lightweight, long-term comfort BCR® Glove Liners for use with latex, vinyl, and nitrile gloves
• Facemasks – Non-shedding face masks for particle and bacterial filtration
• Mops & Accessories – Mop systems, tools, and accessories for cleaning isolator and cleanroom floors, walls, and ceiling surfaces

These high-quality cleanroom and contamination-control products are now available in our Berkshire Corp. Department at QSource.com. If you have further questions about how Berkshire products can work in your controlled environment, please contact us via email, our Web site form, or by calling us at 800-966-6020.

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