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Contents
1. Executive Summary.........................................................................................................................2
2. Introduction ....................................................................................................................................3
3. Rework Process...............................................................................................................................4
4. Equipment List ................................................................................................................................6
5. Conclusion.......................................................................................................................................8
6. Bibliography ....................................................................................................................................9
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1. Executive Summary
This report outlines the importance of correctly handling static sensitive electronic components while
reworking printed circuit boards (PCBs) by implementing and enforcing an Electrostatic Discharge
(ESD) Control Program to minimise the risk of component damage.
It opens with an introduction explaining what electrostatic charge is, how it is generated and what
effects a discharge can have on PCBs or components. It follows by describing which measures can be
put in place to combat ESD through the use of a Control Program and the application of the relevant
British Standards.
The main body of the document provides an overview of the manual rework process and discusses
the ESD safety requirements, storage methodologies and choice of materials from which a fully costed
equipment list for the static sensitive area is derived.
Finally the report concludes with a brief paragraph stressing the effects on the reliability of the static
sensitive equipment throughout the rework process and its effects thereafter if we do not implement
an ESD Control Program.
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2. Introduction
Static electricity is an unavoidable everyday occurrence. During the handling process devices can be
subjected to electrostatic charge generated by the contact and separation of bodies at differing
electrical potentials. Factors such as size, shape and the type of material govern the amount of charge.
When a charged device finds a path to ground, either directly or by contact through a charged operator
or tool, a discharge of current takes place. This can result in a catastrophic or latent failure, where the
discharged current can burn holes in an integrated circuit (IC) or, worse, degrade the function of the
equipment so that it fails at a later date in the presence of the consumer.
The implications of field failures, recalls, repairs and reputation damage are very real and could
adversely affect this facility. To combat these undesirable ESD circumstances, Tom Watkins (2011)
maintains that the rework environment and the product must be kept Neutral. This is achieved by
avoiding the use of insulators such as plastics which allow the build-up of charge and utilising
grounding conductors in an effort to dissipate charge both safely and gradually.
The current mandatory Standard BS EN 61340-5-1 (British Standards Institute, 2007) provides
direction on the protection of electronic devices from electrostatic phenomena. It is supported by a
recommended User Guide PD CLC/TR 61340-5-2 (British Standards Institute, 2008) which aids the
Design Engineer in the application of an ESD Control Program. Puszczewicz (2011) provides an example
of such a Program, where unprotected ESD sensitive parts are handled, which comprises of the
following key elements:
ESD training for all personnel.
Definition of an ESD Protected Area (EPA).
Personal and equipment grounding methods.
Inclusion of an Ionisation system.
A safe scheme for ESD handling and storage
A compliance verification plan.
The main objective of this report will be to comply with BS EN 61340-5-1 while specifying the technical
requirements for the design, use, monitoring and control of an EPA. Within this dedicated, clearly
identified zone, electronic devices susceptible to damage by discharges of ≥100V human body model
(HBM) can then be handled through the complete rework process with minimal risk.
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3. Rework Process
The manual rework process diagram, shown in Figure 2 on the next page, illustrates the complete
operational cycle from delivery into the EPA, through inspection, unpacking, rework, testing, and
finally back into storage to await redistribution.
Adherence to proven manufacturing systems of inventory control like Kanban and First in First out
(FIFO) storage methods will maximise efficiency, prevent obsolesce by optimising shelf life, and
maintain long term reliability by ensuring stock does not end up forgotten on a shelf only to oxidise.
The entire process must be monitored and subjected to regular quality audits by a designated,
qualified individual. To carry out their roles effectively it is important that the team of operatives who
work within the EPA receive the appropriate training in the following Standards (Ipc.org, 2015):
J-STD-001: Requirements for Soldered Electrical and Electronic Assemblies.
IPC-A-610: Acceptability of Electronics Assemblies.
IPC-7711/7721: Rework, Repair and Modification.
Throughput targets are maintained by doubling up on rework operatives and so to meet production
demands a team of ten individuals is recommended as shown in Figure 1 below:
QTY POSITION FUNCTION
1 Supervisor. Planning and managerial.
1 Production technician. Auditing, break coverage and general support.
1 Incoming materials handler. Unpacking, inspection, recording and distribution.
1 Incoming tester. PCB functional testing*.
2 Rework operative. De-soldering and removal of upgradable component**.
2 Rework operative. Replacement and re-soldering upgradable component.
1 Outgoing tester. PCB functional testing and identification.
1 Outgoing materials handler. Recording, re-packing, inspection and distribution.
Figure 1 – Resource requirement and function.
* Any PCB’s that fail the functional test before the upgradable component is fitted will be returned to
the manufacturer as a non-conformance.
** Brown (2015) insists that the recycling of electronic devices or components must comply with the
Restriction of Hazardous Substances (RoHS) Directive 2002/95/EC, and all defective parts must be
disposed of safely under the European Community Directive 2012/19/EU for Waste Electrical and
Electronic Equipment (WEEE).
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Figure 2 – Rework process.
RESOLDER UPGRADEABLE
COMPONENT
TEST PCB
PALLET OF PCB’S
DELIVERED TO EPA
UNPACKING AND
INSPECTION
REPLACE UPGRADABLE
COMPONENT
DESOLDER UPGRADABLE
COMPONENT
TEST PCB TO VERIFY
FUNCTIONALITY
DISTRIBUTE TO WORK
BENCH STORAGE
RECORD PCB SERIAL
NUMBERS
IDENTIFY UPGRADED
COMPONENT ON PCB
RECORD UPGRADED PCB
SERIAL NUMBER
REPACKING AND
INSPECTION
DISTRIBUTE TO PALLET
STORAGE AREA
PASS
FAIL
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4. Equipment List
Asuni (2015) insists that material selection used within the EPA is of great importance and
consideration should be given to the triboelectric effect of all material choices. Flooring, work
surfaces, furniture, clothing, packing, tools and equipment should all be carefully selected for their
electrostatic properties, while taking care to avoid the use of any insulating materials like glass, plastic
or even dry air. To that end one must ensure that the ESD equipment meets the static dissipative
requirements of BS EN 61340-5-1.
This proposal recommends the use of low maintenance ESD dissipative acrylic floor paint having
evaluated the relatively small size of the rework facility (125m2
) and determined that it undergoes a
low level of activity. Acrylic painted flooring is highly abrasion proof and is not influenced by humidity,
requiring only routine cleaning, stripping and buffing to preserve its electrical properties.
Overhead Ionisers were chosen over the cheaper bench top blower variety mainly because they
prevent the operatives from suffering Dry Eyes, while covering the entire surface area of the
workstation without being obstructed by any bench top obstacles, Watkins (2011).
While important in the workplace, humidity control as a method of ESD prevention has been excluded
from the program as it can bring other issues such as moisture contamination, oxidisation, and
possible high voltage leakage paths.
Rework equipment and electronic PCB assembly tools have been selected with conductive tips for
removal and replacement of faulty components. Additionally, hot air rework tooling has been included
as it is ideal for damage-free repair. Consideration was given to temperature profiling and an
inspection station, but was deemed unnecessary as the upgradeable component was a simple,
accessible through-hole mounted resistor.
Figure 3, below, provides a comprehensive list of the equipment required to implement an ESD Control
Program at our facility for 10 operatives, but excludes ESD training expenses. The table includes
quantities, individual costs which also double as hyperlinks to the suppliers’ website, and packaging
consumables which have to be stock managed. All components were chosen from reputable online
suppliers of readily available technology, compliant with BS EN 61340-5-1.
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EPA EQUIPMENT LISTOPERATIVES
QTY EQUIPMENT FUNCTION COST (£)
10 Unisex ESD lab coat, white. Cover clothing in chest & arm area. 27.45
10 Dissipative gloves, medium. Handling static sensitive devices. 8.67
20 Full coverage foot strap, medium. ESD grounding of all operatives. 5.71
10 Antistatic face mask ESD prevention (optional). 22.50
4 Dual wire wrist strap and 3700mm
lead.
ESD grounding for up to 4 mobile
operatives as required
30.29
TOOLS
2 ESD mobile trolley, with earth drag
chains.
2 operatives transporting and
temporarily storing materials.
341.50
4 ESD toolkit, drivers and cutters. 4 operatives reworking the PCB’s. 33.95
4 ESD soldering iron, 80W. 4 operatives reworking the PCB’s. 149.02
4 SMD rework station, hot air. 4 operatives reworking the PCB’s. 91.25
ESDAREA
10 ESD dissipative acrylic paint, light
grey, 5L
Used on floors for ESD dissipation
where the activity is not so intense.
139.10
8 ESD anti-static chair with feet (IS-
AS2)
8 operatives using seating with
static dissipation directly to earth.
88.00
7 ESD static dissipative workbench
with legs.
6 operatives repairing and testing
PCB’s, plus 1 bench for supervisor.
384.60
4 Meech A221-600 standard ioniser. 4 operatives reworking the PCB’s. 655.70
6 Neostat C2 workstation kit include-
ing wrist strap, 1000 x 600mm.
4 operatives reworking the PCB’s,
plus 2 operatives testing the PCB’s.
54.70
6 Plated shelving racks. For delivery and storage of PCB’s. 64.40
12 PCB rack, 406mm x 275mm x
150mm.
Workbench storage of ESD
sensitive PCB’s.
24.90
4 Small parts cabinet with 48
drawers.
Storage of upgradable components
for rework.
104.00
5 Floor marking tape, 50mm x 66m For marking the boundaries of the
EPA.
11.10
4 Floor, wall and door sign, 300mm
dia.
For use in and around electrostatic
discharge areas.
23.00
2 EPA exit packaging reminder sign,
300mm.
Informative sign. 10.90
2 Wear your wrist strap sign, 300mm Informative sign. 10.90
PACKING
10 Pink static dissipative stretch film,
500mm wide x 300m long.
Storage and packaging. 23.50
10 Packaging bags, 100 off, various. Numerous types have been
selected for storage and handling.
49.47
10 Antistatic cellulose printed tape,
66m long x 48mm wide.
Storage and packaging. 12.90
AUDIT
1 Combo tester with stand and
footplate.
For testing wrist straps and
footwear at the EPA entrance/exit.
277.11
1 Multi-range megohmeter. For carrying out audits and testing. 403.60
1 ESD Standard. Requirements of
ESD control program.
Design aid, BS EN 61340-5-1:2007. 54.00
3 ESD User Guide, handbook. Design aid, PD CLC/TR 61340-5-2. 113.00
TOTAL COST (£) 13564
Figure 3 – EPA Equipment List
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5. Conclusion
Static charge, as Watkins (2011) summarises, is a normal consequence of any component handling
process. There is no escaping the ESD phenomena in todays’ electronic production environment and
the development and execution of a management backed ESD program is crucial for the safe handling
of static sensitive components in our manual rework process. Only in this way can we instil a culture
of conformance to the ESD standards, procedures and control mechanisms.
Ignoring a recommendation to implement an ESD Control Program to protect these components will
place the product at severe risk. We would most certainly see an increase of electrostatic discharge
induced component failures. Some of these faults may not cause malfunction until the device has left
the factory unit, leaving us open to the embarrassment of public scrutiny or even prosecution.
A white paper by Microscan Systems, Inc. (2011) tells us that ESD costs the electronics industry billions
of dollars every year, accounting for as much as 8 to 33% of total product losses. The paper infers that
the most costly type of failure is the one that reaches the customer. This can be harmful to the
reputation of the product and ultimately lead to a loss of potential sales. Further associated costs
would come in the form of increased repairs, replacement parts, shipping, and the inclusion of service
personnel and facilities.
In conclusion the £13.6K investment spent on the implementation of the ESD Control Program will
guarantee a reduction in losses, scrap parts, rework and cycle times resulting in a much quicker Return
on Investment (ROI). Gorajia (2011) supports this in his blog as he discusses the use of Overall
Equipment Effectiveness (OEE) as a metric to gauge and reduce these types of losses.
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6. Bibliography
Asuni, N. (2015). 3. An Overview of ESD Control Procedures and Materials. [online] Technick.net.
Available at: http://www.technick.net/public/code/cp_dpage.php?aiocp_dp=guide_esd_003
[Accessed 09 Dec. 2015].
Barnes, J. (2001). Designing Electronic Equipment for ESD Immunity. [online]
Available at: http://www.eetimes.com/document.asp?doc_id=1143824
[Accessed 09 Dec. 2015].
British Standards Institute (2007) BS EN 61340-5-1:2007 - Electrostatics. Protection of electronic devices
from electrostatic phenomena. General requirements. [online]
Available at: http://shop.bsigroup.com/ProductDetail/?pid=000000000030082389
[Accessed 09 Dec. 2015].
British Standards Institute (2008) PD CLC/TR 61340-5-2:2008 - Electrostatics. Protection of electronic
devices from electrostatic phenomena. User guide. [online]
Available at: http://shop.bsigroup.com/ProductDetail/?pid=000000000030207324
[Accessed 09 Dec. 2015].
Brown, J. (2015) Waste Electrical & Electronic Equipment & RoHS Directives. [online]
Available at: http://www.jamesmbrown.co.uk/weee-and-rohs-directives
[Accessed 09 Dec. 2015].
Electrostatics Solutions Ltd (2009) Overview of 61340-5-1:2007. [online]
Available at: http://www.electrostatics.net/ESD_Guide/technical/overview.htm
[Accessed 09 Dec. 2015].
Gorajia, J. (2011) ‘Achieving Optimal Manufacturing Flow using OEE (Part 4)’, Blogs.mentor.com, 9
February. [online]
Available at: https://blogs.mentor.com/jay-gorajia/blog/2011/02/09/achieving-optimal-manufacturing-
flow-using-oee-part-4/
[Accessed 09 Dec. 2015].
Ipc.org, (2015). IPC Free Documents | IPC. [online]
Available at: http://www.ipc.org/ContentPage.aspx?pageid=IPC-Free-Documents
[Accessed 09 Dec. 2015].
Microscan Systems, Inc. (2011) Technical Considerations for Controlling ESD in Electronics Manufacturing.
[online]
Available at: http://www.indatasys.com/technical_ESD_paper.pdf
[Accessed 09 Dec. 2015].
Manasa.K. (2012). Challenges in Integrated Electronic System Designs. [online]
Available at: http://www.slideshare.net/ManasaSushmitha/challenges-in-electronic-system-design
[Accessed 09 Dec. 2015].
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Perfectproduction.com, (2015). Overall Equipment Effectiveness. [online]
Available at: http://www.perfectproduction.com/oee.htm
[Accessed 09 Dec. 2015].
Puszczewicz, E. (2011) ESD Basics and Protection. [online] Transforming Technologies.
Available at: http://www.slideshare.net/ericpuszczewicz/esd-basics-by-transforming-
technologies?related=1
[Accessed 09 Dec. 2015].
Smallwood, J. (2015). A Guide to ESD. [online]
Available at: http://www.compliance-club.com/archive/old_archive/030923.htm
[Accessed 09 Dec. 2015].
Solutions.3m.co.uk, (2015). [online] Available at:
http://solutions.3m.co.uk/3MContentRetrievalAPI/BlobServlet?lmd=1154017253000&locale=en_US&asse
tType=MMM_Image&assetId=1114279231283&blobAttribute=ImageFile
[Accessed 09 Dec. 2015].
Staticworx, I. (2015). Taking Charge of ESD on the Manufacturing Floor. [online] Staticworx, Inc.
Available at: http://www.staticworx.com/articles/removing-esd-from-manufacturing-floor.php
[Accessed 09 Dec. 2015].
Voldman, S. (2004). ESD Physics and Devices. Chichester, West Sussex, England: John Wiley & Sons.
Watkins, T. (2011) Esd control-in-electronic-assembly. [online] Transforming Technologies.
Available at: http://www.slideshare.net/TransformingTech/esd-
controlinelectronicassembly?qid=1be0c508-1be2-4796-823d-e830ff00a64c&v=qf1&b=&from_search=1
[Accessed 09 Dec. 2015].
