What is the difference between conductive and static dissipative plastics?

Surface resistance. Conductive materials measure below 10 to the 6th power ohms per square and bleed charges away almost instantly, which can be too fast for energised boards. Static dissipative materials measure between 10 to the 6th and 10 to the 9th power ohms and bleed charges slowly enough to be safe around powered assemblies. Both protect devices; the speed differs.

What does anti-static actually mean?

Anti-static means the material resists generating a triboelectric charge when it rubs against itself or other materials. It is a charge prevention property, not a discharge path. An anti-static bag that prevents charging but does not ground you will not protect a board from a charged operator, which is why ESD programmes combine anti-static with dissipative or conductive paths.

Which ESD class do I need for SMT line totes?

Most SMT and PCB handling uses static dissipative containers in the 10 to the 6th to 10 to the 9th ohm range, because they are safe near populated boards. Conductive containers below 10 to the 6th ohms suit component storage and grounded trolley runs where fast bleed is wanted. Match the class to your ESD control plan, not to the sales sheet.

How do I verify a container is really ESD safe?

Measure surface resistance with a calibrated megohmmeter at standard humidity, and ask the supplier for lot test reports rather than a one-time certificate. ESD properties in plastics come from conductive fillers that can vary between resin lots, and humidity shifts readings by an order of magnitude, so test at your actual plant conditions.

ESD Material Classification: Conductive vs Dissipative

Conductive, static dissipative, anti-static — three terms that get used interchangeably and mean three different things. The difference is measured in ohms, and picking the wrong class either fails to protect the board or dumps a charge through it too fast. This guide lays out the resistance bands, what each class does, and which electronics applications each one belongs to. For application context, see our ESD turnover boxes vs trays guide and ESD plastic pallets for SMT guide.

ESD conductive plastic pallets for electronics manufacturing — ESD pallets and containers. The class is defined by surface resistance, not by colour.

The resistance ladder

ESS classification is a ladder of surface resistance, measured per square (surface resistivity) or point-to-point. The industry anchors, from ANSI/ESD and IEC standards, look like this:

Class	Surface resistance	Charge behaviour	Typical colour convention
Insulative (not ESD)	> 10¹² Ω	Holds charge; generates tribocharge	Any — ordinary plastic
Anti-static	10¹⁰–10¹² Ω (typical)	Resists generating charge; bleeds very slowly	Often pink (amine-free)
Static dissipative	10⁶–10⁹ Ω	Bleeds charge in milliseconds — safe near powered boards	Often black or grey
Conductive	< 10⁶ Ω	Bleeds charge almost instantly; needs grounding	Black (carbon-filled)

Read the ladder as speed control. Conductive is a fast lane, dissipative is a speed limiter, insulative is a wall. The art of ESD control is choosing the bleed speed appropriate to what is inside the container.

Why faster is not always better

Beginners assume conductive is the “best” class. It is not that simple:

A charged operator touching a conductive container creates a hard discharge path. The container bleeds instantly — and the current spike can couple into nearby components.
Energised or populated boards should not sit on surfaces that can create low-ohm paths between their nodes.
Dissipative surfaces bleed a charge in milliseconds — fast enough to prevent field build-up, slow enough to avoid the spark.

Rule of thumb: storage and transport of raw components → conductive is fine; populated and powered assemblies → dissipative. Many plants run conductive shelving and trolleys (always grounded) with dissipative containers on top.

What anti-static really means

Anti-static is not on the same axis as conductive vs dissipative. It describes tribocharge generation: an anti-static material resists building charge when rubbed. It says nothing about how fast a charge, once present, leaves the material.

Practical consequences:

An anti-static pink bag prevents charging itself but will not protect a board from a charged person.
A conductive tote bleeds charges but can still generate tribocharge on its surface in dry air.
The best ESD plastics combine both: low tribo generation and a dissipative bleed path. Carbon-filled dissipative compounds generally achieve this; ask for tribocharge test data if handling is friction-heavy.

Application mapping

Conductive (< 10⁶ Ω)

Component storage totes and reels on grounded shelving
ESD floor mats, trolley frames, grounding trolleys
Trays for bare boards between process steps on grounded lines

Static dissipative (10⁶–10⁹ Ω)

PCB turnover boxes moving between SMT, test and rework — including populated boards
Workbench mats and container lids handled near powered equipment
Battery trays and panels (see our ESD boxes vs trays comparison)

Anti-static (tribocharge control)

Outer bags and film for shipping
Cover shrouds and liners where the priority is not generating charge
General plant items — chairs, bins, packaging — inside an EPA

Humidity: the silent variable

Surface resistance in plastics moves with humidity — a container that measures 10⁸ Ω at 50% RH can read 10¹⁰ Ω at 20% RH in a dry winter plant, crossing class boundaries. Two practical defences:

Specify the test humidity in your purchase spec (typically 12% RH per ANSI/ESD STM11.11 for worst-case dry conditions, or standard lab conditions for comparison).
Re-measure seasonally with a calibrated megohmmeter if your plant runs dry in winter.

How ESD properties are built into the plastic

Ordinary plastics are insulators. ESD plastic gets its conductivity from fillers mixed into the resin:

Carbon black — the workhorse: cheap, effective, black. Dominates conductive and many dissipative grades.
Inherently dissipative polymers (IDP) — alloyed into the base resin for permanent, humidity-stable, lighter-coloured dissipative compounds.
Surface treatments (topical anti-stats) — cheap but wear off with washing. Acceptable for shipping film, not for containers that go through wash loops.

The filler is why ESD containers cost more than standard ones and why lot consistency matters: filler dispersion varies between batches, and a poorly dispersed lot measures fine in places and insulative in others.

Procurement checklist

Pick the class from your ESD control plan: conductive for grounded storage, dissipative near populated boards.
Specify surface resistance range and the test standard with humidity.
Ask for lot-level test reports, not a single certificate from three years ago.
Confirm the ESD property is permanent (filler or IDP), not topical, if containers are washed.
For wash-loop containers, verify resistance survives your wash chemistry and temperature.
Ground the mobile fleet: ESD trolleys need grounding wheels or drag chains regardless of container class.

ESD containers from a factory that moulds them

LSY Plastic injection-moulds ESD turnover boxes, trays, parts boxes and pallets in Foshan on Japanese-imported machines from 180T to 2500T, with an in-house mould workshop — the same plant that supplies ESD logistics components alongside OEM parts for BYD, OPPO, vivo and Desay. Resin lots are compounded with conductive filler to a specified resistance band, so the class on the datasheet is the class in the crate.

Get an ESD container specification

Tell us your ESD control plan resistance bands, what the containers carry (bare components vs populated boards), and your washing process. We will propose the compound class, format and test protocol.

WhatsApp: +86 19311059570
Email: fstyx01@lsyplastic.com