When someone or something discharges a static charge to an electronic component, at the microscopic level of modern circuitry the damage can be catastrophic and potentially fatal as well. ESD trays are used to control static and protect sensitive electronics in manufacturing, transportation, and storage.
Importance of ESD Trays in Electronics Manufacturing
Any time a person picks up, touches, or even gets close to a part that is electrically grounded, there’s risk of an ESD “event”, a jolt of electricity jumping from the person to the part, like a mini-lightning strike. ESD trays reduce those risks.
Any time parts slide along a surface, whether it is in an auto loader, a pick and place machine, or simply moving things out of the way on a workbench, there’s risk of an ESD event. ESD trays reduce those risks.
Any time electronics are powered up or tested, there may be a remaining charge on the parts, even after power is removed. A grounded person touching a charged part or moving that part to a workbench or a metal tray can create a rapid discharge, an ESD event, that damages the part. ESD trays reduce those risks.
The damage from an ESD event may be immediately obvious – catastrophic failure – the part no longer works. The damage may be hidden – a bit of internal circuitry is damaged, a carbon track is created that acts as an unintended conductive path – and a damaged part is assembled into a finished product. ESD trays reduce these risks also.
Wherever trays are used to handle electronics, ESD trays should be used.
Benefits of ESD Trays
An ESD tray should protect its contents while enhancing the process in which it is used. You should expect any, or all, of the following benefits.
- Electrical protection
- Mechanical protection
- Improved handling
- Automation compatibility
- Increased productivity and yield
Specifications of ESD Trays
Two basic types of ESD Trays
- Generic trays are similar to totes and corrugated boxes. Generic ESD trays are simple trays that get loaded randomly, in bulk, and are best for manual transportation of items that are already packaged and individually protected. Generic trays are not good for fragile components or parts.
- Custom trays are optimized for your parts and your process. Through collaboration with your ESD tray supplier, your tray specification will be created. The tray specification becomes the roadmap for the design and manufacture of your tray. It will include:
- Mechanical details of your parts that will be used with the tray
- Mechanical details of the tray that will hold your parts and be compatible with your process
- Electrical properties of the trays – most ESD trays will be specified as “dissipative trays” or “antistatic trays”, although sometimes they will be described as “conductive trays”
- Temperature rating – high temp, bakeable trays are available for parts that must go through a heating process for moisture removal, curing, or other elevated temperature exposures
- Other requirements such as chemical compatibility, automation requirements, and other process or product needs
JEDEC Trays – a shortcut for specifying ESD Trays
JEDEC matrix trays are a reliable, proven method to handle and process parts in an automated environment. They have spread beyond the originating semiconductor industry and are being used for other types of electronic components, optical and photonic products, and purely mechanical parts. Pick and place automation, ESD protection, and utilization of standardized process equipment are the most common reasons companies choose to use JEDEC trays.
JEDEC Tray Standards define shared characteristics to allow commonality among equipment, hardware, and other support products. The external tray dimensions and features provide reference points for device location and features to allow the use of automated handling systems.
What to expect in an ESD Tray Specification
Material:
Most ESD trays are molded of some type of conductive plastic. We use our NoStat® ESD-safe composite polymers which are formulated for a range of temperature requirements. ABS is a popular material for non-bakeable trays and PES is recommended for applications requiring continuous use at temperatures up to 180℃. For more information, read about conductive plastics here.
Caution: Some trays are manufactured with MPPO polymers, a low cost engineering thermoplastic, and labeled as bakeable trays with a variety of temperature limits. We consider these materials to be unsuitable at most baking temperatures. Although they may not melt at rated temperature, UL and the manufacturers of MPPO material usually list the continuous service temperature in the range of 100°C and we have seen multiple examples of MPPO trays rated for 150°C that have distorted badly after baking at the higher temperature.
ESD trays must be electrically conductive. The most common materials include carbon. Carbon fiber, rather than carbon powder, is preferred to provide electrical conductivity. Although carbon powder is lower cost than fiber, the amount needed to ensure dissipative properties results in carbon sloughing – you can literally write with trays made with powder-filled materials. The risk of contamination and decreased mechanical strength is high when carbon powder is used. In contrast, carbon fiber improves mechanical performance and is non-sloughing, resulting in cleaner, stronger trays.
We also have the option of using a topical antistatic coating to make ESD trays using non-conductive plastics. We use it most for 3D printed ESD trays, when conductive materials are not offered, and for a select group of low cost JEDEC shipping trays. The coating is not considered permanent and washes off easily so its use is restricted to appropriate applications.
Surface Resistivity:
Expressed as “ohms per square” (Ω/sq.), surface resistivity is the preferred way to measure ESD tray conductivity. It is easier and more repeatable to measure than surface resistance or decay rates.
Size:
ESD trays can be made in almost any shape and size but most often they conform to the JEDEC outline. The popular JEDEC Matrix Tray Outline requires a nominal length of 315mm (12.4”) and width of 135.9mm (5.35”).
Another popular ESD tray format is the waffle pack chip tray. Waffle packs were first used by the semiconductor chip fabs to handle bare silicon die and that remains the most common use. However they are also used for other small parts that may benefit from the waffle pack format and process compatibility. The most common size is 2” square but 3” and 4” waffle packs are also used.
Capacity:
The tray specification should state the maximum number of components the trays can hold (e.g., 40 parts) and of the pocket matrix (e.g., 4 x 10).
Color:
Most ESD-safe materials use carbon to create electrical conductivity so the default color for most ESD trays is black. We have formulated our most popular non-bakeable NoStat® polymer in blue to help prevent accidental baking. We also offer low temp ESD trays in a few other colors. Custom color formulations are possible at additional cost and minimum order quantities.
Applications of ESD Trays
ESD trays offer the obvious benefit of protecting parts from damage due to static electricity. But because they don’t carry a static charge well, they are less likely to attract dust and dirt. This makes ESD trays great for handling dust-sensitive parts or working in a clean environment. Some examples include:
- Semiconductor and electronic manufacturing
- Photonics, optics, and sensor manufacturing
- Component handling and storage
- Transportation and shipping
- Cleanroom and laboratory environments
How to Choose the Right ESD Tray
Choosing the correct tray for your application requires consideration of the parts going into the tray, where and how the tray will be used, the quantity of trays needed, the tray manufacturer, the cost, and the availability.
Your parts:
The size, shape, fragility (mechanically and electrically), value, and consistency are primary factors to include when choosing a tray.
Your process:
You want a tray that can withstand normal, and possibly abnormal, use. Know how you will be handling and moving the trays. Include details about chemicals and temperatures to which the trays will be exposed. If third-party equipment or automation will be used, get their requirements. If the trays will be used for storage or shipment, what are the size, space, and weight constraints?
How many trays:
Determine whether trays will be used over and over repeatedly or once through and gone. Different materials and manufacturing processes will be used to make tens of trays vs. tens of thousands.
Success through partnership:
Your tray manufacturer can be a valuable team member. Chances are good that your needs are not unique. Choosing a tray manufacturer who understands your application, asks the right questions, and has knowledge to share greatly improves your chance of success and makes your job easier and more enjoyable.
Lead time:
The timing of your needs, together with the quantity needed, will help define the best manufacturing technology to use for your ESD trays. Be realistic so that you get the best solution, which may not be the fastest.
Price:
Tray price usually turns out to be one of the least important selection criteria. When you consider the value of your parts, the impact the tray can have on achieving a reliable process, the risks of losing parts, shutting down production, or missing dates, getting the best quality ESD tray from a trusted supplier is a great investment in your success.
ESD Tray Maintenance and Handling
In many ways, ESD trays are simply precision packaging. They should be handled with care, avoiding unnecessary roughness or drops or environmental exposures. Most ESD trays will stack and it is usually best practice to keep them stacked to avoid damage. This is especially true if trays are being reused. Do not toss them randomly into a box where they can get chipped or cracked.
Most ESD trays are made of some type of plastic and may be sensitive to both heat and chemical exposure. Be aware of the temperature limit of your trays and avoid contact with solvents if you have not confirmed compatibility. If you must clean your trays, compressed air and brushing are good options. If liquid cleaning is required, aqueous processes are best and isopropyl alcohol is usually acceptable, but check first.
If you choose to use ESD trays that are not permanently conductive, and instead have an antistatic coating, avoid any liquid exposure as it may remove the coating and, with it, the ESD protection.
Pricing & Availability
The cost of an ESD tray can range from a few dollars to hundreds of dollars each. When the tray design and/or usage warrants building a new, custom mold, the NRE charge can be $10k to $100k. But there are other options to get a new custom ESD tray that require no new tooling. The design, size, material, and quantity are all important factors. Here are some general guidelines
- Small order quantities usually have higher unit prices than high volume.
- Price increases exponentially with tray size because of material content and the cost of manufacturing equipment for large trays.
- High temperature ESD trays also have higher cost because of raw material prices.
- Using a standard format tray like JEDEC matrix trays can be much less costly than developing a completely new tray design.
Availability usually depends on the manufacturing process used. In general, ESD trays are custom designed and manufactured. Off-the-shelf simply means a manufacturer has enough demand for a specific custom tray that they carry some inventory.
We have some ESD trays for a few common part types that are stocked and available for shipment. Most ESD trays we supply are custom manufactured to order and are shipped in a few weeks after receipt of order.
Request a Quote
ESD Trays are the best answer to many questions. Your next step is to tell us about your needs so we can build the correct tray for your application. A drawing, model or sample of your part and a few simple details are all we need to connect you with your custom ESD tray.
Here is the information we will use to determine your best tray option and generate your quotation.
- Sample, CAD model, or drawing of your part with accurate dimensions (± .005”/0.13mm)
- Quantity of parts for which you will need trays, now and overall, and anticipated ordering quantities
- Timeline for your tray requirements
- Temperature requirements – Do you need bakeable trays (rated up to 180°C) or non-bakeable (rated up to 60°C) or another tem
- How tray will be used – shipping, storage, processing, automated or manual handling
- Any special requirements for your process
Call us, send an email, or click here to receive your quote.