Question: We are currently experiencing difficulties with static electricity in our paint booth. All of our products cannot be cleaned well enough before topcoating and we are looking into several solutions, but wondering which actually works. I also can’t get the color to go on evenly. The sprayed paint seems to dance before landing on the sheet in funny patterns.
In the painting industry, electrostatic discharge is a constant challenge in a world where perfection is the only option–and dust and static are a constant. Static attracts dust and unwanted particles, making it very difficult to keep surfaces clean, causing blemishes in paint finishes and other work surfaces. It’s absolutely essential to eliminate static from the environment–at every stage of painting–in order to avoid costly reworking.
Specialty ionizers for the auto body industry are used to eliminate surface contamination. These ionizers allow you to keep the surface clean so you can avoid unnecessary reworking and buffing, saving both time and money. The guns work twofold: as a forceful blow off gun that easily removes particulate from surfaces and as a neutralizer to remove the charges responsible for the attraction of contaminants to product surfaces in the first place.
Anti-static wipers have been developed to clean off surfaces and can be used to clean surfaces as well. Static is caused by friction, so wiping down surfaces to remove dirt can actually make the static problem worse. The anti-static wipers are made with a specially designed fabric that will not tribocharge and will not lead to more static buildup.
ESD inspection/assembly gloves are designed to be worn when handling items that can be affected by static. They are made with dissipative nylon fibers that reduce charge generation. The gloves will decrease contamination to parts due to oils, dust and fingerprints. Cut resistant ESD inspection gloves are also available if you must handle items with sharp edges such as glass and metal.
Transforming Technologies provides comprehensive knowledge of electrostatic issues, effective solution-oriented products and outstanding, friendly service.
Because customer needs periodically include requirements for consultation, training, auditing or verification, we offer Professional ESD Services such as trainings or audits.
Please contact us for more information on our professional services and insure that your static control program is as effective and efficient as possible.
General Static Charge Audit
Find out if your facility has static charge in locations that can be harmful to your manufacturing process. The work includes benchmarking of each step of the production line, measuring electric fields and electromagnetic interference caused by electrostatic discharge. A report is supplied with interpretation of results and assessment of the magnitude of each item found.
Additionally, this service can also include a search for ESD induced transient EMI. This can be important in facilities with lots of computer-driven robotics or automated testing. This type of EMI can disturb microprocessor operations resulting in locked up or stopped robots, other robotic unexplained behavior or cause good parts to test bad.
Includes a complete static charge audit and detailed review of each step in the manufacturing process. If you prefer, the study can focus on one part of the manufacturing process, for example photolithography.
Where problems are identified a selection of choices of solutions are recommended. In addition. The study focuses on identifying the steps required to achieve best practices concerning personnel grounding, garments, equipment grounding, hand tools, chairs, work surfaces and automated handling procedures. A report is supplied with recommended upgrades to the facility intended to improve facility ESD safety.
Ionizer Performance Verification
Find out if the ionizers in the process are working properly and if they are correctly designed in so that they can achieve the results required, If the ionizers are in need of maintenance or adjustment you will know it. If ther ionizers can be made to work better, you will receive recommendations. If the ionizers used are the wrong type or if additional ionizers are required, the report will include these facts.
Ionizer Service: Clean and Calibrate
Corona ionizers collect material from the environment much like a dust precipitator. That material lowers the efficiency of the ionizer and must be removed. Also as tools and fixtures are moved in the cleanroom, the balance of the ionizer is effected. For both of these reasons and because the control circuitry in the ionizer drifts over time, the ionizers require maintenence.
No ESD control program can succeed without the help and cooperation of the production team. LBL offers a seminar to teach the people manning your production floor about static charge and how the various steps in a control program work.
ESD Issues for the Senior Manager
LBL understands the complex issues that arise from being in charge of quality management and safety. LBL will work with senior management to consolidate best the practices and drive standardization across the organization.
Specific Problem Solving
Wether you are just starting your ESD control program or static discharge has been a main concern for years, LBL understands that every static problem is unique, ranging from the simple to the incredibly complex. Contact LBL to discuss any issues, big or small that you may have.
Contact us today for more information on ESD professional services
Introducing Transforming Technologies ESD Mat Selection Guide
Whether it be an ESD Table Mat or an ESD Floor Mat, making the best choice can be difficult. With the help of our ESD Mat Selection Guides, we have condensed all the selection criteria such as material construction, resistance ranges, surface, color, style, or size into two separate charts for your convenience.
Ionizers remove static from surfaces that cannot be grounded. You will find two common types: AC or Alternating Current and DC or Direct Current. This presentation reviews the pros and cons of each technology and will help you decide which ionizer will work best for your application.
For more information, contact Transforming Technologies 419-841-9552.
The difference between DC and AC ionization is the way the emitter points function. In AC, like the Transforming Technologies Ptec & BFN Ionizers, the same emitter point alternates between releasing positive and negative ions. This means they inherently have a voltage balance. This is because if an emitter gets dirty and isn’t functioning, the other emitters are still alternating between positive and negative ions. This also means that the ions are closer together which makes it more likely for them to recombine. This means normally higher fan speeds are needed to reduce the time between the fan and the surface that needs to be ionized.
DC ionizers have separate emitters for positive and negative ions. This means that it’s a little more difficult to ensure a low voltage balance and if one emitter stops working, it throws the unit out of balance. These types of units require a lot more consistent maintenance/monitoring to ensure a good voltage balance. The benefits are that the emitters are separate so there is less of a chance of recombination of the ions. This allows the DC units to operate at a lower fan speed which is very beneficial when your components are small or you are in a clean room.
This week’s ESD Q&A question is about Constant Monitors:
Question: What would be the the advantages or disadvantages of using a single wire or dual wire monitor?
Single wire constant monitors are ideal for general use applications. They are cost effective and simple to use. Dual wire constant monitors, on the other-hand, should be used for very sensitive applications. They are more expensive, but dual wire constant monitors are the most accurate wrist strap monitoring technology available.
Single Wire Constant Monitors Explained:
Single wire constant monitors work on capacitance technology and use single wire wrist straps. The monitors send a signal down the wire to the wrist strap and measures for capacitance. If there is a mass indicated (approximately that of a person) at the end of the coil cord, the monitor assumes that the person is connected and puts the monitor into an unalarmed state.
Single wire continuous monitor systems are used widely, but they can be fooled. Some people have dry skin and do not make good contact with the wrist strap. The single wire monitors are not able to detect if the person is actually electrically connected. For most applications, this is not a concern. But if you have a very senstive process, you should consider using Dual Wire Continuous monitors.
Dual Wire Constant Monitors Explained:
Dual wire monitors use resistance based technology and dual wire wrist straps. The monitors send a small current through the wrist strap wire and measures resistance of the current as it returns back. Dual wire wrist straps must be used because they are specially designed to rely on the operator’s skin to close that current loop. When this happens you can be assured that the operator is connected and that voltage is being drained through the wrist strap. If the wrist strap breaks or the operator’s skin is dry and does not allow for the current to flow from one side of the strap to the other, the alarm will sound.
Dual wire monitoring is the most accurate wrist strap monitoring technology available. Single wire systems are very common and cost effective, but they simply detect that a person is wearing a wrist strap and put the monitor into an unalarmed state. Resistance monitors actually measure the resistance of the wrist strap in combination with the person and alarm if the product exceeds preset levels. This accurate measurement ensures reliability.
Transforming Technologies offers three constant monitor families:
Ohm Metrics CM400 Series – Single Wire Constant Monitors
Spartan CM300 Series – Single Wire Constant Monitors
Resistance Ranger CM1600 Series – Dual Wire Constant Monitors
All of Transforming Technologies’ Constant Monitors can be found on the web here:
This week’s ESD Q&A question comes from StaticCare reader Tim, he asks:
Question: What type of instrument should I use to measure the resistance on our conveyor belt?
Thank you for taking the time to submit your question to Transforming Technologies.
You will want to use a surface resistance meter with a 2.27 Kg (5lb) electrode, such as the SRM500K, for the measurement. For a flat belt conveyor, you can put the electrode on the conveyor belt and measure the resistance to equipment ground. For an edge belt conveyor, place a metal plate on the conveyor and measure the resistance from the plate to equipment ground. You may want to isolate one side of the plate from the belt to make sure that each belt is grounded.
Transforming Technologies will answer questions concerning all things ESD: static causes, threats, ESD prevention, best practices and all things static in a feature we call ESD Q&A. If you have ESD questions that you would like to be answered, email firstname.lastname@example.org with Q&A in the subject line.
Question: What measurement or measurements do I need to make when auditing an ESD worksurface?
There are three primary measurements for evaluating a work surface; Resistance Point to Point (RTT – also known as Resistance Top to Top), Resistance to Groundable Point (RTGP) and Resistance to Ground (RTG).
Figure 1 – Resistance To Ground (RTG)
Resistance to Ground Measurement
For general auditing purposes, the primary measurement is RTG. This measurement is made using a 5 lb electrode connected to the positive terminal of the resistance meter. The electrode is placed on the work surface in the most heavily used area. The negative lead is connected to electrical ground. This measurement assures that the mat is connected to AC Equipment Ground. ESD standard procedure says to test at 10 volts, and if the measurement exceeds 1.0 x 106 ohms, switch to 100 volts. If you are certain that your worksurface material has a resistance greater than 1.0 x 106 ohms, you may want to start at 100 volts to save time.
A simple and safe way to connect to AC Ground is by using a grounding plug, such as the Transforming Technologies AD22. The AD22 assures a solid connection to the third wire ground of an AC outlet, while insulating the plug from the hot and neutral wires. Always check electrical outlets for proper wiring before using grounding plugs.
If the resulting RTG measurement is within your required limits, no further work surface testing is required and you can proceed to the next work surface. Should the RTG measurement exceed your limits, clean the work surface with an approved cleaning product, check all wiring connections to make sure that they are secure and re-test. Should the measurements still exceed your limits you will then want to conduct a Resistance to Groundable Point (RTGP) measurement.
Figure 2 – Resistance Point To Groundable Point (RTGP)
Resistance to Groundable Point Measurement
This measurement is similar to the RTG measurement except that the negative lead is attached to the grounding point (snap) of the work surface. The testing is performed using 100 volts when the expected resistance is greater than 1.0 x 106 ohms.
Should this measurement provide a reading that is within your requirements the problem is somewhere between the snap and AC Ground. Typically, either the ground wire became disconnected or it is faulty. Check and verify all wiring between the work surface and the AC equipment ground.
If this measurement also provides a value that exceeds your requirements, then there may be a problem with the work surface. A point-to-point resistance measurement can be done to verify the performance of the work surface material.
Figure 3 – Resistance Point To Point (RTT)
RTT – Resistance Point-to-Point
This measurement is made using two 5 lb electrodes. The electrodes are placed 10” apart on the work surface in various locations. Figure 3 is an example of a point-to-point test.
The testing is performed using 100 volts when the expected resistance is greater than 1.0 x 106 ohms.
If the reading meets your requirements, there is possibly a connection problem with the groundable point. Should the reading exceed your limits the work surface is likely faulty and should be replaced.
It is important that RTG measurements be made regularly. The frequency of testing is dependent up on internal requirements and testing history. RTG testing must be performed even if constant monitoring is in place, as constant monitors verify ground connection of the worksurface, but not the performance of the worksuface.
Question: Is there really a need for an ESD wastebasket?
It is fair to wonder why there is a need for ESD wastebaskets. If the waste basket resides underneath a workstation and stays there permanently, it is extremely unlikely that a wastebasket could present a danger to ESD sensitive devices, regardless of the field voltage that may exist on the basket.
However, there are a number of circumstances when the wastebasket could present a significant hazard to electronic products. The following are just a few examples of potentially risky scenarios:
Work surface cleaning: The operator lifts the wastebasket to the edge of the work station to collect the debris being removed. Should product be present on the work surface and not contained in a shielding container, there is a good opportunity for exposure to electrostatic fields that exceed safe limits.
Lead trimming/board cleaning operations: When trimming component leads or using aerosol cleaners on PCBs (Printed Circuit Boards), some operators will hold the PCB over the wastebasket to catch the clippings or solvent run-off. Many times the PCB will be placed well into the waste container to assure catching the unwanted materials. This operation puts PCBs and ESD sensitive devices very close to potentially significant electrostatic fields.
Aisle proximity: Some wastebaskets have been observed in close proximity to production floor aisles where product transfer carts pass or may be parked. ANSI/ESD S2020 requires items that generate 2000 volts or more (measured at 1” from the item) be kept at least 12” from ESD sensitive devices. Using ESD wastebaskets eliminates the risk of carts being parked next to static generating baskets.
Taking out the trash: The simple action of removing trash from the ESD sensitive area could generate a dangerous amount of static. Static is caused by movement, specifically friction. So moving the trash cans to empty them or removing the plastic trash bags from the can generates voltage and they could come in close proximity to sensitive components on the way out of the area.
While company ESD policies may prohibit some of the actions mentioned above, it does not mean that they will not occur from time to time. ESD wastebaskets provided assurance that the wastebasket will never be an ESD threat to your product.
What Do ESD Standards Say?
The ANSI/ESD S20.20 standard says to remove all insulators from the ESD protected Area (EPA). There is nothing specifically mentioned in the standard about Trash Cans or Waste Baskets. But most trash cans as well as trash bags are plastic, which is an insulators that can generate significant charges. It is better to be safe than sorry when is comes to static damage which is why we developed ESD-Safe Trash Cans and Waste Baskets.
Transforming Technologies offers three ESD wastebaskets in static dissipative polypropylene :
Question: When measuring ESD Product such as ESD Mat resistance, I have noticed that the resistance measures higher on some of my older ESD rubber mats when using 10V and will sometimes be greater than 10^9 ohms. Switching to 100V will lower the resistance into the green, passable range(less than 10^9 ohms). If the mat passes at 100V, is that sufficient to give the mat a pass? When should I use 10 volts vs. 100 volts?
Industry standards specify the test voltage required when testing or verifying ESD control items (i.e. mats). For verification of mats, or work surfaces, you can reference the ESD Association TR53 Compliance Verification document. This is a free download at www.esda.org (select the Standards tab and scroll down to TR53).
The following rule applies for resistance testing of ESD control items:
Perform the test at 10 volts. If the resistance is < 1.0 x 10^6 ohms record the reading.
If the measurement at 10 volts is ≥1.0 x 10^6 ohms, switch to 100 volts, make your measurement and record the result.
Most ESD mat materials are designed to have a resistance greater than 1.0 x 10^6 ohms, so you can start your testing at 100 volts. In the example that you stated, the mat that you tested meets the requirements. If you are seeing the values creep higher it would be wise to test the older mats more frequently to verify that they are still under 1.0 x 10^9 ohms.
Periodically, Transforming Technologies will answer questions concerning all things ESD: static causes, threats, ESD prevention, best practices and all things static in a feature we call ESD Q&A. If you have ESD questions that you would like to be answered, email email@example.com with Q&A in the subject line.
Question: What materials are the biggest cause ESD damage?
Answer: Plastics and other synthetic materials cause the most trouble because they are insulators and trap charges on their surfaces.
Materials that are insulators hold an electric charge and cannot easily transfer the charge and cannot be grounded to earth by common means. Conductors are just the opposite. They are materials that easily transfer a charge. Examples are metals, water, carbon and people. Understanding insulators and conductors is an important part of creating an ESD action plan.