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WHAT CAUSES ELECTROSTATIC CHARGE?

When any two surfaces make contact and then separate, ‘tribocharging’ occurs – electrons move from one surface to the other causing an imbalance. The amount of static electricity generated depends upon the materials involved, the area of contact, and the relative humidity of the environment (with charge generation increasing significantly as the environment becomes drier).

 

Typical electrostatic voltages:

 

Walking across a carpet: 1,500 – 35,000 volts

Walking across an untreated vinyl floor; 250- 12,000 volts

Unwinding a roll of tape: 9,000 – 15,000 volts

 

The higher voltage is generated at low humidity – a typical air-conditioned electronic manufacturing environment. 

WHY IS IT A PROBLEM?

ELECTROSTATIC DISCHARGE, ESD, is the spontaneous transfer of this electrostatic charge from one item to another. It can generate heat and melt circuitry in electronic components.

As little as 100 volts can damage an electronic component. To feel an ESD event it must be 2,000 volts.

As we use more electronic components in more compact designs, our ESD risk increases. The smaller a component, the more sensitive it is, and therefore more likely to be destroyed or damaged by a sudden surge of static charge. 

 

Types of damage:  

In a catastrophic failure the component is destroyed, can normally be detected in an inspection and therefore repaired or replaced. Latent defects pose a more serious problem: a component is damaged but not destroyed, may pass the inspection phase undetected and then be installed in the field. 

Early field failure can involve costly repair work for the customer, and a loss of business and reputational damage for the supplier.

 

One study calculated the repair costs to fix a component failure as:

£7 if the device fails

£70 if the device fails on the board

£700 if the device on the board fails in the system

£7000 if the system fails due to the device on board

 

ESD controls limit and prevent ESD events, saving you time and money. 

 WHAT SHOULD YOU DO ABOUT IT?

  • Define your ESD Protected Area (EPA)
  • Identify the materials within your EPA – conductors, insulators, ESD sensitive items – and how to protect them
  • Control access to your EPA and monitor your ESD equipment

 

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Static Control Packaging

Look at our ESD Product range

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ESD Explained

Learn about ESD with our 'ESD Explained' article

Identify the types of materials in your ESD protection area, and how to protect them:

  • Conductors (including people) – electrical current passes easily through them, and they can be grounded. See our range here:
    • Personnel grounding devices:
      • Wrist straps
      • Foot grounders
      • Personnel grounding test devices
    • Workstation grounding devices:
      • Dissipative work surfaces (and associated ESD cleaners)
      • Conductive floor mats
      • ESD workstation monitors

 

  • Insulators – electrical current does not flow easily through them, they hold the charge, and cannot be grounded. These items must be removed from the EPA, ‘neutralised’ with ionisers, or replaced with an ESD protective version.
    • Ionisers:
      • Bench top ionisers
      • Neutralizing air nozzles / hand gun
      • Overhead ionisers                 
    • ESD protected products:
      • ESD garments and gloves
      • Conductive foam and shunt bars
      • Conductive and dissipative flooring
      • ESD carpeting, tiles, etc
      • Dissipative floor finishes
      • Dissipative binders and document protectors
      • ESD workstation equipment
      • ESD packaging:
        • Bags, boxes, etc.
        • ESD tape
      • ESD material handling containers
      • ESD Field service kit
      • ESD sensitive items – must be shielded when stored or transported outside the EPA.
        • ESD packaging:
          • Bags, boxes, etc.
          • ESD tape
        • ESD material handling containers
        • ESD Field service kit

ESD SURVEYS- BOOK YOUR NO-CHARGE ESD SURVEY TODAY

What happens in an ESD survey?

Your Inelco Hunter Business Manager will visit you along with a Desco specialist if required, and will carry out a survey to provide quantifiable data to allow you to make improvements to your ESD process. Following the path of component parts from goods inwards to the end of your production line, they will visually assess and use specialist equipment to test selected areas in your facility: goods in, stores, production area, testing area, despatch. They will test leads, earthing points, flooring and work benches; assess the movement of people and the control of access to sensitive areas; and they will provide you with verbal explanations as you accompany them. A survey will usually take 1-2 hours depending upon the size of your facility and the complexity of your production.

 

Following your survey you will be sent a written Assessment Report that will include numeric findings, gaps between the programme and industry standard EN 61340-5-1, ANSI/ESD S20.20 and IPC-A-610E, references to best practices and recommendations for improvements and suitable products. This report can be used for your next audit.

STATIC MANAGEMENT PROGRAMME

A Static Management Programme (SMP) continuously monitors your ESD process control system throughout all stages of manufacturing. It captures data from workstations, equipment and ESD event continuous monitors, and provides a real-time picture of critical manufacturing processes.

This includes:

  • System based on continuous detection in production areas
  • Ongoing readings at every stage where product could be damaged
  • Constant collection, reporting and analysis of data
  • Equal attention to machine, bench and personnel monitoring
  • User-friendly tools for non-specialist ESD coordinators
  • Ability to demonstrate robust static control measures to customers
  • Transition away from reactive, fire-fighting approaches to proactive programs based on active management of entire ESD environment

EQUIPMENT USED IN THE SMP:

Ground Master (Equipment Ground Monitor): The Ground Master Monitor provides continuous monitoring of proper grounding for up to eight tools: measuring impedance in accordance with ANSI/ESD S20.20; monitoring EMI voltage signals on each ground to assist in equipment diagnostics; providing intelligent information to a facility monitoring system with detailed status on each ground connection.

 

WS Aware (Workstation Monitor): The WS Aware Monitor is a dual workstation continuous monitor for operators, ESD work surfaces and metal tools. It continuously monitors all grounding parameters for either two metal and two ‘soft’ grounds, or for four metal grounds, with optional ‘big brother’ alarm for occasions when the operator approaches sensitive components before correctly plugging in his or her wrist strap. 

 

EM Aware (ESD Event Monitor): The EM Aware Monitor monitors three key parameters that keep you aware of critical symptoms of ESD problems: ESD events, change in static voltage field, and ionizer performance. The thresholds for these parameters are fully adjustable.

 

 

SMP ADVANTAGES

  • Companies can now determine and evaluate their Return On Investment
  • Savings may be realized from:
  • Higher yields & process efficiencies
  • Elimination of costly inspections
  • Fewer customer complaints
  • Less re-work and lower field returns
  • Budgets driven by performance data
  • Leverage SMP to attract and retain customers
  • New source of competitive advantage – compliance as a selling point
  • Tip the scale in project negotiations