Five bags off the internet, one pass
Pink poly is the default answer for shipping anything with a circuit board in it. It is cheap, it is pink, and it says antistatic on the box. Cortec’s film plant ordered five pink poly antistatic bags from online sellers and ran them through the surface resistance test in its quality control lab. The requirement is ANSI/ESD STM11.11: less than 1 x 10^11 ohms on the outer surface. One of the five passed. The other four were, for ESD purposes, ordinary poly bags.
In the same test, Cortec’s VpCI-125 HP Permanent ESD bags measured up to 60 times better than the requirement. The two-minute video above shows the meter readings. This post covers why the results split the way they did and what it means for a shop that ships sensors, control boards, motor drives or instrument assemblies.
Why pink poly fails: the antistatic is a coating, not the film
Most pink poly gets its antistatic property from a surfactant added to the film. The surfactant migrates to the surface and attracts a thin layer of moisture from the air, and that moisture layer is what bleeds off static. It is a humidity-dependent, time-limited effect. In a dry warehouse in January, or after the bag has sat on a shelf for a year, or after it has been handled and rubbed, the surface resistance climbs and the bag stops doing its job. Nothing about the bag looks different. That is why four out of five off-the-shelf bags failed a test the buyer assumed they would pass.
Permanent ESD film builds the dissipative property into the polymer itself. The surface resistance does not depend on humidity, does not wear off with handling and does not age out on the shelf. That is the difference the meter is measuring in the video, and it is the difference between a bag that protects a board in Phoenix in July and one that only protects it in a lab at 50 percent relative humidity.
The second problem pink poly never addressed: corrosion
ESD is only one of the two things that damage electronics between the plant that builds them and the plant that installs them. The other is corrosion on connector pins, solder joints, relay contacts, terminal blocks and the steel or aluminum housing the board is mounted in. A control board travels through a trailer, a cross-dock, an unheated warehouse and a job site. Every temperature swing along the way condenses moisture on the coldest metal in the package.
Cortec’s article on protecting aircraft avionics in the supply chain makes the point that even when installation and operation are tightly controlled, the handling, storage and transport stages in between are where the exposure happens. The same is true of an industrial VFD or a machine control panel.
VpCI-125 HP film handles both problems in one bag. The film is permanently dissipative, and it releases a vapor phase corrosion inhibitor that forms a molecular layer on every metal surface inside the package, including contacts and pins that no coating can reach. The layer dissipates when the bag is opened and leaves nothing on the board. No separate desiccant, no separate VCI insert.
Where this applies in the plants we serve
- Panel builders and machine builders shipping control assemblies to integrators or end users, where the panel may sit on a construction site for weeks before power-up.
- Repair and reman shops returning drives, servo amplifiers and boards to customers. A board that arrives with a corroded connector is a warranty call.
- Manufacturers of instruments and sensors that go into export shipments, where the container is the harshest environment the product will ever see.
- Aerospace and defense suppliers, where both the corrosion requirement and the ESD requirement are written into the purchase order and the pink poly bag will not pass an audit.
- Spare parts cribs holding boards and drives for years. This is the shelf-life case where surfactant-based antistatic bags quietly stop working.
For boards that need ESD protection but are wrapped or interleaved rather than bagged, EcoSonic ESD paper gives the same dual protection in a kraft paper format, and for electronic assemblies that need corrosion protection but are not static sensitive, standard VpCI-126 bags are the lower-cost choice.
One related cross-over: if the housing or chassis that the board mounts in has been through your wash line or blast booth before assembly, it is clean bare metal and will rust faster than a painted part. Bagging the finished assembly in VpCI-125 or VpCI-126 covers the housing and the electronics together.
Which products
- EcoSonic VpCI-125 HP Permanent ESD bags, 4 x 5 inch and 10 x 12 inch; other stock sizes and custom sizes by quote
- EcoSonic ESD multimetal VCI kraft paper in 35# and 60# rolls for wrapping and interleaving
- VpCI-126 Blue zip-close bags for non-static-sensitive assemblies
- BioPad emitters for cartons with air space, and VpCI-101 emitter devices inside control panels and electronics enclosures
Use the VpCI product selection guide to match metal type and shipping environment to the film.
Talk to us
If you are buying pink poly today and have never put a meter on it, we would rather you know before your customer does. Tell us what you ship and how long it sits, and we will recommend a bag or paper and send a sample. Contact us.
Source: Cortec Corporation published test video and product data. ANSI/ESD STM11.11 surface resistance method.
