Metro Electronics Storage Guide: ESD and PCB Solutions

In electronics manufacturing, precision and reliability are of the utmost importance. Every circuit board, microchip, and connector plays an integral role in the functionality and performance of the final product. Therefore, manufacturers must adhere to specific ESD (electrostatic discharge) protocols to maintain a safe working environment and guarantee product quality.

Nothing is more frustrating (and cost-prohibitive) than spending time and money manufacturing electronic devices only to find out they don’t work because of a damaged component. Even worse is when a product goes to an end user and fails to work properly due to an ESD issue. No engineer wants their product to make it into the field and be a “dud.”

ESD may not always be perceptible to humans, but it poses a significant threat to electronic components. Even the slightest discharge can cause significant damage. For example, while 100 volts is the typical threshold in most settings, as little as 10 volts can damage microelectronics to some degree. For some perspective, it takes close to 3000 volts to be perceptible to a human, and up to 30k volts can be generated by just walking across a floor.

It's also important to note that damage does not always cause immediate failure. In many instances, ESD impedes performance in the field and/or leads to a future failure in the field. Since the repercussions of such damage can be unpredictable, mitigating ESD risks is non-negotiable.

At Metro, we understand the importance of ESD safety for Electronic Manufacturing Services (EMS). That's why we offer a full range of effective ESD management solutions to ensure a safe working environment and uphold uncompromising product quality standards.

Learn more about our ESD and PCB storage solutions.

What is ESD, and How Does it Affect Electronics?

ESD refers to a typically invisible and sudden discharge of electrical current. ESD typically occurs when two objects close to one another create a highly charged electrostatic field.

Before an electrostatic discharge event occurs, an electron imbalance on the material's surface causes an electrostatic charge to build. Several events can produce this charge, such as shoes scuffing against a surface or rubbing certain materials together. The buildup of electrical charge leads to one surface gaining electrons, resulting in a negative charge, while the other loses electrons, resulting in a positive charge. The electrical charge is brought back into balance during the ESD event by transferring electrons via current. (Source)

One of the biggest dangers of ESD is that it can occur at almost any stage of the manufacturing process, and because it’s “invisible,” it can happen unknowingly. Any static buildup can damage electronic components such as printed circuit boards (PCBs), impacting functionality and creating long-term problems.

In addition to causing physical damage, ESD can create a logistical nightmare. Static charges can affect everything from delays in manufacturing and delivery to the equipment involved with the event. We often think of how static discharge can physically damage circuitry. However, it can also cause issues with measurement devices and the performance of precision robotics (e.g., autonomous robots in distribution centers). Manufacturers must prioritize ESD safety and ensure their workstations are static-safe to avoid technical and practical complications resulting in financial loss.

How To Prevent ESD in an Electronics Manufacturing Environment

Since internal damage from ESD is not always visible but can lead to shortened component lifespans and premature failure, prevention is key. All electrical components should only be handled in an ESD-protected area (EPA) where electrostatic fields and voltages are at low levels.

To prevent the generation and accumulation of ESD, it's essential to minimize or eliminate sources of static electricity. This can be achieved by using materials that do not generate or hold static charges, such as conductive or dissipative plastics, metals, or fabrics.

Grounding yourself and your equipment is an important method to prevent ESD damage. This process involves connecting all electrically conductive and dissipative items in the workplace to ground with a low electric potential, such as the floor. Ground provides a point of low electrical potential that enables areas of high electrical potential to funnel through, allowing residual current or buildup to escape. It is important to note that the floor isn’t automatically grounded.

electronics manufacturing

Metro’s Electronics Storage Solutions

At Metro, we carry various ESD products that help eliminate the risk of ESD damage by preventing electrical charge buildup during manufacturing and storage. Our ESD solutions can be used for semiconductor manufacturing, PCB manufacturing, PCB and electronics assembly/handling, battery manufacturing, and more.

Metro PCB Handling Cart with SmartTray ESD-Safe Trays

When working with circuit boards and SMT components, it's important to handle them carefully. Metro’s SmartTray cart system has been designed to maximize productivity and safely store and transport sensitive components during PCB manufacturing and electronics assembly/handling.

Each preconfigured PCB cart includes Metro ESD trays in both economy and premium tray options to provide superior ESD protection. The premium trays include ESD tray inlays.

The carts come in two size options: one that can manage 20 trays and one that can hold and transport 30 trays. PCB handling carts are also available in front-load and side-load options depending on the most convenient load design for your facility.

Carts can also be outfitted with grounding wires and other accessories for a variety of applications.


  • Offers permanent ESD protection for sensitive electronic parts.
  • Trays can be suspended in the cart for optimum ergonomic access.
  • Bar code labeling and color coding allow trays & tray contents to be tracked throughout the manufacturing/assembly process.
  • Trays and tray contents can be scanned while in cart, as opposed to scanning each item individually.
  • Carts, trays, and tray contents can be sorted & categorized according to product type, application, or dedicated to a specific production line.

Metro PCB Handling Cart with SmartTray ESD-Safe Trays


Molded from Metrostat™, a material offering premium ESD protection, the SmartTray fits all Metro tray cart systems, all competitive side load and end load models, and most tray-based cart systems. Utilizing smart trays for PCB material handling and storage helps minimize damage and provides superior ESD protection.

SmartTray ESD Tray Inlays

Optional ESD tray inlays can be used with Metro SmartTrays for maximum ESD protection. In addition to providing ESD protection, they also can be added for maximum product protection. The inlay surface provides grip, ensuring your PCBs and other components don’t slide around on the hard plastic surface.

Premium inlay: Our premium inlay option also offers superior resistance to heat, abrasions, and chemicals. The soft, dissipative top layer is ideal for soldering and assembly areas. Our premium ESD inlays have the option of being both dissipative and conductive. For a dissipative solution, place the mat on the tray with the blue side up. For a conductive solution, face the black side out.

Economy inlay: Our economy option also provides static dissipative ESD protection and a cushioned surface for PCB transport. The economy tray should not be used in soldering and assembly applications. Unlike our premium inlays, these are just dissipative.

ESD tray with ESD inlay

ESD Cart Covers

We carry ESD Cart Covers for our PCB Handling Carts to provide extra protection when storing or transporting PCBs and SMT components. The durable cover material is conductive on the outside and dissipative on the inside, with a brass zippered front flap and side paperwork pouch. Cart covers are especially useful when transporting ESD-sensitive materials through a non-ESD location within the production facility or when storing/staging products overnight.

Metro ESD cart Cover

Metro Shelving Tote Boxes

Proper storage and organization are key elements to maintaining an EPA. We carry storage totes made from electrically conductive and electrically dissipative materials, so you can choose the right product for your electronic parts handling requirements.

CAS — Refers to Bentron, a conductive polypropylene-base material. This material contains a carbon additive to provide an electrically conductive path through the material. Bentron has a surface resistivity of less than 1 x 10 5 ohms/sq. Our conductive shelving tote boxes are black in color.

BAS — Refers to Benstat, Metro’s patented static dissipative polypropylene-base material. Benstat has a surface resistivity of more than 1 x 10 5 ohms/sq. and less than 1 x 1012 ohms/sq. Our dissipative shelving tote boxes are blue.

ESD tote boxes

PCB Grid Boards

PCB Grid Boards are an optional accessory for standard Metro totes to maximize storage density within the containers. These inserts provide a pattern of slots where boards can be captured by the bottom edge, allowing PCBs to be stored vertically. PCB Grid Boards are available in conductive and static dissipative materials to fit the TB91000, TB92000, and TB93000 series footprints.

Metro PCB grid boards

Kitting Carts

Metro Kitting Carts (PT Trucks for PCB Carriers) efficiently handle totes, PCB carriers, trays, or other material handling containers. With mobile kit carts, boards and other electronic components are kept safe during the manufacturing or assembling process.

Metro Super Erecta PCB handling carts are available in many configurations, including adjustable or fixed width. You can also choose from single-bay, double-bay, and triple-bay options with 2-brake and 2-swivel casters in your choice of resilient rubber or polyurethane. Units can also be made conductive by utilizing a grounding bracket and grounding cable.

metro kitting carts pcb carriers

SMT Reel Shelves

Many electronics manufacturing industries utilize surface-mount technology (SMT) to mount electrical components directly onto the surface of a printed circuit board. During the pick-and place process, the components are often delivered to the production line wound on reels. The pick-and-place machines remove the parts from the tapes and place them on the PCB.

Metro’s SMT component reel shelving offers an efficient method of storing and transporting standard-size reels backed by the durability of our Super Erecta wire shelving platform. These Super Erecta Brite-plated shelves can be mixed and matched with standard Super Erecta shelving, posts, and casters to create a reel handling and storage system to address the precise needs of PCB manufacturers.

Benefits and features:

  • 15 reel capacity for 13" (330mm) — 15" (381mm) reels*; 78 reel capacity for 7" (178mm) reels
  • Can be configured and reconfigured to meet your exact needs
  • Integrates with standard SES components
  • Conductive with the use of aluminum or polymer conductive split sleeves

MEtro SMT reel shelves

Stencil Racks

Stenciling is the process of taking a raw board and printing (stenciling) the pathways. This process utilizes metal stencils (usually a thin sheet of stainless steel) with laser-cut openings and solder paste to attach surface-mounted components to a circuit board. Once the components are placed, the board goes into an oven, which melts the solder and seals the connection.

Metro’s SMT Stencil Frame Rack allows you to create a compartmentalized stencil storage solution utilizing the Metro Super Erecta Shelving System. SMT stencil racks are available in chrome or Type 304 stainless steel and can be made conductive with the use of conductive split sleeves and 5MESD conductive casters for mobile applications.

Metro SES Stencil Frame Rack ESD

Electronics Casters

Metro’s electrically conducive caster wheels fit Super Erecta Shelf posts to create mobile units like shelf carts. We carry conductive stem casters and conductive stem casters with non-marking wheel treads, both of which are available with optional foot-operated brakes.

These casters are designed to prevent electrostatic discharge in ESD-safe environments by conducting static electricity out of the cart, through the wheels, and into the conductive floor. If you need to transport sensitive electronic components like circuit boards, using conductive casters in conjunction with aluminum split sleeves and a grounding cable ensure that mobile units are properly grounded to ESD floor surfaces.

We recommend using both a drag chain and ESD caster for redundant paths for the current to travel to ground, thus maximizing ESD protection.

Metro ESD casters

Ensure You Have a Safe Working Environment with Metro’s ESD and PCB Solutions

According to industry experts, product losses due to electrostatic discharge (ESD) are estimated to range from 8% to 33%. Even at the lowest estimate, this figure is still too high for something that can be better avoided, especially considering the demand for PCBs and other components for the growing EMS market.

Manufacturing engineers can take many steps to limit their direct involvement in ESD damage, such as wrist straps, heel straps, shoe covers, and anti-static clothing. But it is also important to consider environmental solutions, particularly related to storage and transport.

At Metro, technological advancements are at the forefront of our product designs. We offer cutting-edge smart solutions for maintaining a safe environment when working with PCBs, hard drives, sub-assemblies, and other sensitive electronic components.

Ready to learn more about how we can help you build an ESD-safe environment? Visit our website to shop all Metro electronics solutions.