Posts
One of the responsibilities of an ESD Coordinator is to verify the effectiveness of the ESD Control program of his organization.
The only way to do that is by conducting an ESD Compliance verification or conducting an ESD audit.
ESD coordinator is required to plan out the ESD auditing activity. The ESD Compliance verification or ESD audit plan should at least contain information of where and when the audit to be conducted.
The ESD audit plan should be communicated to the organization about the planned ESD audit. Area manager should assign an auditee during the ESD audit when ESD Control program plan compliance verification is done.
Effectiveness of the ESD audit would not be successfully evaluated without a proper ESD Audit Checklist.
ESD coordinator should plan out the ESD audit checklist ahead before conducting the ESD audit. The ESD audit checklist should cover both the verification compliance of the ESD Control program plan Technical elements and the general requirements of the ESD Control program plan.
The ESD audit results should be analyzed in statistical manner and trend of results should be studied.
The ESD audit results should also be communicated to the Managements of the organization and support from the Managements should be sought to ensure the ESD Control program is running effectively.
Besides conducting a formal ESD Compliance verification or ESD audit periodically, the effectiveness of the ESD Control program could be further enhanced when an informal or a surprise audit is carried out.
In general, ESD Compliance verification or ESD auditing should not be taken lightly, rather it should be given utmost attention and seen as a very important tool to improve the organization’s ESD Control Program.
ESD Protective Packaging Material for ESD Control Program
ESD sensitive items are not only susceptible to esd damage, but they are also susceptible to damage by shock and vibration during handling, transportation and storage.
Many ESD protective packaging materials are created by industries expert with the intent to protect ESD sensitive items from being damage by electrostatic discharge, shock and vibration.
Example of ESD protective packaging materials in the market place are:
• ESD box
• ESD bag
• ESD foam and bubble
• ESD tray
• Anti static tube
• ESD tape and film
• ESD rubber band
It is the responsibility of an ESD Coordinator to select and evaluate ESD packaging materials before they are introduced and used inside the ESD Protected area or EPA.
The ESD protective packaging materials can be evaluated and tested based on ANSI/ESD S541 standard which outline the testing methods and the performance limit for the ESD packaging materials.
Anything that is used outside the EPA area should be:
• low charging
• dissipative or conductive for intimate contact
• provide shielding from electric field and ESD
The definitions of material property are:
Dissipative:
A dissipative material has a surface resistance which falls in the range of
1x10E4 to <1x10E11 ohm or Volume resistance in the range of 1x10E4 to <1X10E11 ohm when tested in accordance to ANSI/ESD STM11.11 and ANSI/ESD STM 11.12 respectively.
Conductive:
A surface conductive material has a surface resistance < 1x10E4 ohm or a volume conductive material has a resistance < 1x10E4 ohm when tested in accordance to ANSI/ESD STM11.11 and ANSI/ESD STM 11.12 respectively.
Low charging:
A low charging material is a material which has a low charge generation when come in contact and separated from the other material.
And there is no correlation between resistance measurement and the ability of the material to be low charging.
Electric field shielding:
An electric field shielding material has a surface resistance < 1x10E3 ohm or a volume resistance < 1x10E3 ohm when tested in accordance to ANSI/ESD STM11.11 and ANSI/ESD STM 11.12 respectively.
This material has the ability to attenuate electric field emanating from a charged object.
Electrostatic discharge shielding:
An electrostatic discharge shielding material has the ability to attenuate the effect of ESD. The ESD shielding bag has < 50 nanojoules energy inside when tested in accordance to ANSI/ESD STM 11.31.
Many of the ESD protective packaging materials that are used inside EPA can be evaluated and tested by using an appropriate Surface Resistance Test kit.
It is the responsibility of the ESD Coordinator to decide the ESD packaging materials for use in his/her ESD Control Program.
Many ESD protective packaging materials are created by industries expert with the intent to protect ESD sensitive items from being damage by electrostatic discharge, shock and vibration.
Example of ESD protective packaging materials in the market place are:
• ESD box
• ESD bag
• ESD foam and bubble
• ESD tray
• Anti static tube
• ESD tape and film
• ESD rubber band
It is the responsibility of an ESD Coordinator to select and evaluate ESD packaging materials before they are introduced and used inside the ESD Protected area or EPA.
The ESD protective packaging materials can be evaluated and tested based on ANSI/ESD S541 standard which outline the testing methods and the performance limit for the ESD packaging materials.
Anything that is used outside the EPA area should be:
• low charging
• dissipative or conductive for intimate contact
• provide shielding from electric field and ESD
The definitions of material property are:
Dissipative:
A dissipative material has a surface resistance which falls in the range of
1x10E4 to <1x10E11 ohm or Volume resistance in the range of 1x10E4 to <1X10E11 ohm when tested in accordance to ANSI/ESD STM11.11 and ANSI/ESD STM 11.12 respectively.
Conductive:
A surface conductive material has a surface resistance < 1x10E4 ohm or a volume conductive material has a resistance < 1x10E4 ohm when tested in accordance to ANSI/ESD STM11.11 and ANSI/ESD STM 11.12 respectively.
Low charging:
A low charging material is a material which has a low charge generation when come in contact and separated from the other material.
And there is no correlation between resistance measurement and the ability of the material to be low charging.
Electric field shielding:
An electric field shielding material has a surface resistance < 1x10E3 ohm or a volume resistance < 1x10E3 ohm when tested in accordance to ANSI/ESD STM11.11 and ANSI/ESD STM 11.12 respectively.
This material has the ability to attenuate electric field emanating from a charged object.
Electrostatic discharge shielding:
An electrostatic discharge shielding material has the ability to attenuate the effect of ESD. The ESD shielding bag has < 50 nanojoules energy inside when tested in accordance to ANSI/ESD STM 11.31.
Many of the ESD protective packaging materials that are used inside EPA can be evaluated and tested by using an appropriate Surface Resistance Test kit.
It is the responsibility of the ESD Coordinator to decide the ESD packaging materials for use in his/her ESD Control Program.
ESD sensitive (ESDS) device classification
It is the responsibility of the ESD Coordinator find out the ESDS device classification once he knows the ESD Sensitivity level for the most sensitive device for his product.
This is important as it will tell the ESD Coordinator whether the device is a Class Zero device.
If the device or component is a Class Zero device, the device ESD withstand voltage is less than 250 Volts.
Human Body Model (HBM) ESDS Component Sensitivity Classification, per ANSI/ESD STM5.1
Class 0: < 250 Volts
Class 1A: 250 Volts to < 500 Volts
Class 1B: 500 Volts to < 1000 Volts
Class 1C: 1000 Volts to < 2000 Volts
Class 2: 2000 Volts to < 4000 Volts
Class 3A: 4000 Volts to < 8000 Volts
Class 3B: >=8000 Volts
Machine Model (MM) ESDS Component Sensitivity Classification, per ANSI/ESD STM5.2
Class M1: < 100 Volts
Class M2: 100 Volts to < 200 Volts
Class M3: 200 Volts to < 400 Volts
Class M4 : > or = 400 Volts
Charge Device Model (CDM) ESDS Component Sensitivity Classification, per ANSI/ESD STM5.3.1
Class C1: < 125 Volts
Class C2: 125 Volts to < 250 Volts
Class C3: 250 Volts to < 500 Volts
Class C4: 500 Volts to < 1000 Volts
Class C5: 1000 Volts to < 1500 Volts
Class C6: 1500 Volts to < 2000 Volts
Class C7 : > or = 2000 Volts
A Class Zero device is susceptible to damage by human body voltage greater than or equal to 250 Volts.
An ESD Control program which is set up in accordance to the ANSI/ESD S20.20 Standard requirement has the capability to provide protection for ESDS device which is susceptible to damage by human body voltage greater than or equal to 100 Volts.
In another word, ESD Control program which is set up in accordance to the ANSI/ESD S20.20 standard requirement is capable to provide protection for Class Zero devices which has HBM ESD withstand voltage from 100 Volts to < 250 Volts.
Electronic devices which are susceptible to damage by human body voltage less than 100 Volts requires more stringent ESD control limit than those limit specified in the ANSI/ESD S20.20 standard.
This is important as it will tell the ESD Coordinator whether the device is a Class Zero device.
If the device or component is a Class Zero device, the device ESD withstand voltage is less than 250 Volts.
Human Body Model (HBM) ESDS Component Sensitivity Classification, per ANSI/ESD STM5.1
Class 0: < 250 Volts
Class 1A: 250 Volts to < 500 Volts
Class 1B: 500 Volts to < 1000 Volts
Class 1C: 1000 Volts to < 2000 Volts
Class 2: 2000 Volts to < 4000 Volts
Class 3A: 4000 Volts to < 8000 Volts
Class 3B: >=8000 Volts
Machine Model (MM) ESDS Component Sensitivity Classification, per ANSI/ESD STM5.2
Class M1: < 100 Volts
Class M2: 100 Volts to < 200 Volts
Class M3: 200 Volts to < 400 Volts
Class M4 : > or = 400 Volts
Charge Device Model (CDM) ESDS Component Sensitivity Classification, per ANSI/ESD STM5.3.1
Class C1: < 125 Volts
Class C2: 125 Volts to < 250 Volts
Class C3: 250 Volts to < 500 Volts
Class C4: 500 Volts to < 1000 Volts
Class C5: 1000 Volts to < 1500 Volts
Class C6: 1500 Volts to < 2000 Volts
Class C7 : > or = 2000 Volts
A Class Zero device is susceptible to damage by human body voltage greater than or equal to 250 Volts.
An ESD Control program which is set up in accordance to the ANSI/ESD S20.20 Standard requirement has the capability to provide protection for ESDS device which is susceptible to damage by human body voltage greater than or equal to 100 Volts.
In another word, ESD Control program which is set up in accordance to the ANSI/ESD S20.20 standard requirement is capable to provide protection for Class Zero devices which has HBM ESD withstand voltage from 100 Volts to < 250 Volts.
Electronic devices which are susceptible to damage by human body voltage less than 100 Volts requires more stringent ESD control limit than those limit specified in the ANSI/ESD S20.20 standard.
ESD sensitive (ESDS) device sensitivity level
The most important thing that an ESD Coordinator must know before setting up an ESD Control program for his organization is the ESD sensitivity level for the most sensitive component or part used in the product manufactured by the organization.
By knowing the ESD sensitivity level of the most sensitive ESDS component, it helps the ESD coordinator to establish the ESD controls required for his ESD Control program.
Basically an ESDS electronic device can be damaged by three common mechanisms:
• Discharge from a charged human body into the ESDS device a.k.a Human Body Model (HBM) damage mechanism
• Discharge from a charged conductive part of a machine into the ESDS device a.k.a Machine Model (MM) damage mechanism
• Discharge from a charged ESDS device to a grounded conductive surface a.k.a Charged Device Model (CDM) damage mechanism
The ESD sensitivity level of the ESDS electronic device is commonly documented in the
Material or Component Data sheet or Component Reliability Data sheet.
Some ESDS electronic component manufacturer would tabulate out all the three, i.e. HBM, MM and CDM ESD withstand voltage level and some would only tabulate out only the common HBM and MM ESD withstand voltage level of the device.
ESD withstand voltage is the maximum ESD level that the ESDS can withstand without being damaged.
Anything above the ESD withstand voltage level, the ESDS device or component would either be malfunctioned or damaged permanently.
There is a variety of testers available in the marketplace where semiconductor electronic device manufacturers could test their devices in accordance to the ANSI/ESD standards.
• HBM ESD testing : ANSI/ESD STM 5.1
• MM ESD testing : ANSI/ESD STM 5.2
• CDM ESD testing : ANSI/ESD STM 5.3.1
Knowing the ESD sensitivity levels of the most sensitive ESDS device being handled in the organization would not only help the ESD coordinator to set up appropriate ESD Controls but also would help the ESD coordinator to set up an ESD Control program which is cost effective for his organization.
Under certain circumstances where the ESD sensitivity level for the most sensitive ESDS component is unknown which occurs most of the time, the ESD coordinator can set up his ESD Control program based on ANSI/ESD S20.20 standard requirement. ANSI/ESD S20.20 standard specify controls which provide protection for ESDS component from damage by Human Body voltage greater than or equal to 100V.
By knowing the ESD sensitivity level of the most sensitive ESDS component, it helps the ESD coordinator to establish the ESD controls required for his ESD Control program.
Basically an ESDS electronic device can be damaged by three common mechanisms:
• Discharge from a charged human body into the ESDS device a.k.a Human Body Model (HBM) damage mechanism
• Discharge from a charged conductive part of a machine into the ESDS device a.k.a Machine Model (MM) damage mechanism
• Discharge from a charged ESDS device to a grounded conductive surface a.k.a Charged Device Model (CDM) damage mechanism
The ESD sensitivity level of the ESDS electronic device is commonly documented in the
Material or Component Data sheet or Component Reliability Data sheet.
Some ESDS electronic component manufacturer would tabulate out all the three, i.e. HBM, MM and CDM ESD withstand voltage level and some would only tabulate out only the common HBM and MM ESD withstand voltage level of the device.
ESD withstand voltage is the maximum ESD level that the ESDS can withstand without being damaged.
Anything above the ESD withstand voltage level, the ESDS device or component would either be malfunctioned or damaged permanently.
There is a variety of testers available in the marketplace where semiconductor electronic device manufacturers could test their devices in accordance to the ANSI/ESD standards.
• HBM ESD testing : ANSI/ESD STM 5.1
• MM ESD testing : ANSI/ESD STM 5.2
• CDM ESD testing : ANSI/ESD STM 5.3.1
Knowing the ESD sensitivity levels of the most sensitive ESDS device being handled in the organization would not only help the ESD coordinator to set up appropriate ESD Controls but also would help the ESD coordinator to set up an ESD Control program which is cost effective for his organization.
Under certain circumstances where the ESD sensitivity level for the most sensitive ESDS component is unknown which occurs most of the time, the ESD coordinator can set up his ESD Control program based on ANSI/ESD S20.20 standard requirement. ANSI/ESD S20.20 standard specify controls which provide protection for ESDS component from damage by Human Body voltage greater than or equal to 100V.
ESD marking and ESD symbol
ESD Control program is setup with the sole intention to protect ESD sensitive or ESD susceptible (ESDS) items such as Integrated Circuits, Boards and Assemblies from ESD damage.
In the Electronics manufacturing line or assembly, we will notice that a variety of ESD materials and ESD equipments are used as part of an ESD control system to protect the ESD sensitive items from ESD damage.
Some of the ESD materials are:
• ESD wrist strap
• ESD flooring material
• ESD shoes
• ESD garment
• ESD foot grounder
• ESD mat
Some of the ESD equipments are:
• ESD hand tool
• ESD air ionizer
• ESD trolley or ESD cart
As there are many electronic devices, materials and equipments used in the ESD protected area, it is important for the employee to be able to distinguish those ESDS electronic devices, ESD materials or ESD equipments from those that are not.
The electronic devices that are susceptible to ESD damage can be distinguished through the ESD susceptibility symbol which it is either paper labeled or molded permanently on the plastic packaging that hold them.
The ESD susceptibility symbol has a reaching hand inside a triangle, with a slash across the hand. Although the color for the symbol is arbitrary, the common color is yellow for the hand with black as the background. Red color, however is not allowed as it suggests hazard to employee.
When the ESD susceptibility symbol is seen on a packaging material, it basically means that the devices inside the packaging is susceptible to ESD damage and necessary ESD precaution is required by the employee when handling the devices.
Similarly the ESD materials and ESD equipments can be distinguished through the ESD protective symbol placing on them.
The ESD protective symbol has a reaching hand inside a triangle and an arc outside the triangle. The arc is in bold. Again the color for the symbol is arbitrary; the common color used is yellow for the hand and black as the background. Red color, however is not allowed as it suggests hazard to employee.
When ESD protective symbol is seen on the any material or equipment, it simply means that the material or the equipment is safe to be used in the EPA area. They are able to provide protection to the ESDS electronic devices or assemblies being handled.
ESD symbol or ESD marking for ESDS electronic devices, ESD material and ESD equipment are crucial in the ESD Control program. Without them, many of the ESDS electronic devices may be wrongly handled without proper ESD precaution and many of the ESD materials or ESD equipments may be wrongly interpreted of their functionality.
ESD symbol or ESD marking on ESD materials or ESD equipments is definitely an advantage. However, it still remain the responsibility of the ESD coordinator to select and evaluate the ESD materials and ESD equipments by following the ESD documents and standards to ensure the material or equipments are fit for use in the EPA.
In the Electronics manufacturing line or assembly, we will notice that a variety of ESD materials and ESD equipments are used as part of an ESD control system to protect the ESD sensitive items from ESD damage.
Some of the ESD materials are:
• ESD wrist strap
• ESD flooring material
• ESD shoes
• ESD garment
• ESD foot grounder
• ESD mat
Some of the ESD equipments are:
• ESD hand tool
• ESD air ionizer
• ESD trolley or ESD cart
As there are many electronic devices, materials and equipments used in the ESD protected area, it is important for the employee to be able to distinguish those ESDS electronic devices, ESD materials or ESD equipments from those that are not.
The electronic devices that are susceptible to ESD damage can be distinguished through the ESD susceptibility symbol which it is either paper labeled or molded permanently on the plastic packaging that hold them.
The ESD susceptibility symbol has a reaching hand inside a triangle, with a slash across the hand. Although the color for the symbol is arbitrary, the common color is yellow for the hand with black as the background. Red color, however is not allowed as it suggests hazard to employee.
When the ESD susceptibility symbol is seen on a packaging material, it basically means that the devices inside the packaging is susceptible to ESD damage and necessary ESD precaution is required by the employee when handling the devices.
Similarly the ESD materials and ESD equipments can be distinguished through the ESD protective symbol placing on them.
The ESD protective symbol has a reaching hand inside a triangle and an arc outside the triangle. The arc is in bold. Again the color for the symbol is arbitrary; the common color used is yellow for the hand and black as the background. Red color, however is not allowed as it suggests hazard to employee.
When ESD protective symbol is seen on the any material or equipment, it simply means that the material or the equipment is safe to be used in the EPA area. They are able to provide protection to the ESDS electronic devices or assemblies being handled.
ESD symbol or ESD marking for ESDS electronic devices, ESD material and ESD equipment are crucial in the ESD Control program. Without them, many of the ESDS electronic devices may be wrongly handled without proper ESD precaution and many of the ESD materials or ESD equipments may be wrongly interpreted of their functionality.
ESD symbol or ESD marking on ESD materials or ESD equipments is definitely an advantage. However, it still remain the responsibility of the ESD coordinator to select and evaluate the ESD materials and ESD equipments by following the ESD documents and standards to ensure the material or equipments are fit for use in the EPA.
ESD Protected area or EPA
An ESD Protected area or rather known as EPA is an area where workers work and deal with ESD sensitive items in a safe environment from harmful electrostatic charges. From a quick glance, this EPA is decorated with many and different type of ESD protective materials and equipments which are used to control the generation and accumulation of electrostatic charges, such as ESD mat, ESD wrist strap, ESD tote box, ESD air ionizer, ESD chair, ESD flooring etc. The EPA is normally identified with a clear signage to indicate that the area is an ESD Protected area.
Controls at EPA
When working in an EPA, workers are required to wear wrist strap while handling the ESD sensitive parts in a seated position.
Tailoring could be made when workers are dealing with hazardous voltage. The use of wrist strap can be exempted with some technical justifications.
The work surface shall be grounded and both conductive and dissipative work surfaces are allowed to be in the EPA, depending on the product’s requirement.
Non essential process insulator such as coffee cup, plastic bottle and personal plastic bag are not allowed to be in an ESD Protected workstation. When essential process insulators are needed on the workstation, the 2kV/inch rule is applied.
When scanning the workstation with a static field meter, a source that gives any reading above the 2Kv in an inch distance shall be kept in a distance at least 30 cm away from the ESD sensitive parts.
Alternatively, ESD air ionizers can be used to neutralize the electrostatic charges on the insulative source or other mitigating ways such as shielding technique can be applied.
Workers shall be trained periodically while working in an EPA. Any untrained visitors such as vendors, customers and external auditors shall be accompanied by a trained worker while in the EPA.
Jigs, tools or surface of automated equipment that has direct contact with the ESD sensitive parts shall be dissipative or conductive in nature and grounded.
ESD garments that are worn by workers shall be checked periodically to ensure
continuous functionality during use in the EPA.
Most established organizations have installed ESD flooring in the EPA. While the presence of ESD flooring definitely make ESD controls much easier, it must be noted that ESD flooring does not work alone and in fact it only works effectively with the presence of ESD footwear.
It is the role of the ESD Coordinator to ensure ESD controls at the ESD Protected area is complying with ANSI/ESD S20.20 standard requirements.
Controls at EPA
When working in an EPA, workers are required to wear wrist strap while handling the ESD sensitive parts in a seated position.
Tailoring could be made when workers are dealing with hazardous voltage. The use of wrist strap can be exempted with some technical justifications.
The work surface shall be grounded and both conductive and dissipative work surfaces are allowed to be in the EPA, depending on the product’s requirement.
Non essential process insulator such as coffee cup, plastic bottle and personal plastic bag are not allowed to be in an ESD Protected workstation. When essential process insulators are needed on the workstation, the 2kV/inch rule is applied.
When scanning the workstation with a static field meter, a source that gives any reading above the 2Kv in an inch distance shall be kept in a distance at least 30 cm away from the ESD sensitive parts.
Alternatively, ESD air ionizers can be used to neutralize the electrostatic charges on the insulative source or other mitigating ways such as shielding technique can be applied.
Workers shall be trained periodically while working in an EPA. Any untrained visitors such as vendors, customers and external auditors shall be accompanied by a trained worker while in the EPA.
Jigs, tools or surface of automated equipment that has direct contact with the ESD sensitive parts shall be dissipative or conductive in nature and grounded.
ESD garments that are worn by workers shall be checked periodically to ensure
continuous functionality during use in the EPA.
Most established organizations have installed ESD flooring in the EPA. While the presence of ESD flooring definitely make ESD controls much easier, it must be noted that ESD flooring does not work alone and in fact it only works effectively with the presence of ESD footwear.
It is the role of the ESD Coordinator to ensure ESD controls at the ESD Protected area is complying with ANSI/ESD S20.20 standard requirements.
ESD Personnel grounding
Still up to today, people remains as the main culprit contributing the most in destroying the sensitive electronic chips used in electronic equipments and gadgets. Because of this reason, ESD Association established an ANSI/ESD S20.20 standard to provide guidelines to organizations across the globe on the protection of their ESD sensitive items from ESD damage greater than or equal to 100 Volts Human Body Model (HBM).
When a person walks, electrostatic charges continuously build up on the person body through the contact and separation process that takes place between the person’s shoe sole and the flooring material.
The electrostatic charges start to discharge from the person when he touches a conductive material. That explains the reason why a person would feel a jolt when he touches a conductive door knob in a cold and dry weather.. Static jolt is felt when static electricity of at least 3000 Volt build up in a person body. But a mere 10 Volts can kill a Tunneling Magnetoresistive head(TMR)straight away without the person knowledge.
In any organization, ESD personnel grounding are given the most attention.
There are two common ways where ESD personnel grounding are controlled:
• Wearing an ESD wrist strap
• Wearing an ESD shoes
ESD wrist strap
When wearing an ESD wrist strap, the wearer has to ensure that the wrist strap band is making an intimate contact with his bare skin. This is to ensure the wearer is really bonded to the ground via the wrist strap.
A good wrist strap usually comes with a 1 Megohm +/- 10%, ¼ Watt resistor to protect the wearer from the hazardous current or electrical shock.
The ESD wrist strap is used to drain the electrostatic charges from the wearer body to the ground.
The lower the resistance measured from the wearer to the ground when the ESD wrist strap is in use, the lower the body voltage would be. This is because the electrostatic charges flow faster to the ground when the total wrist strap resistance is lower.
The total wrist strap system resistance when wrist strap is in use has to be less than 35 Megohm to get a body voltage less than 100 Volts.
ESD shoes
Before buying any ESD shoes, the organization has to ensure that the esd shoes are evaluated with the presence of the ESD flooring. This is because the esd shoes and esd flooring has to work hand in hand like husband and wife to ensure full effectiveness.
To get a body voltage less than 100 Volts, the total system resistance from the wearer through the esd shoes and esd flooring to the ground shall be less than 35 Megohm.
If the organization has a total system resistance greater than 35 Megohm but less than 1000 Megohm, this condition is still acceptable as long as the body voltage of a person is less than 100 Volts.
When an organization is dealing with a more sensitive device which can be easily damaged by a 50 Volts human body voltage, then a total system resistance of the ESD personnel grounding device when in use to ground must be less than 10 Megohm.
When a person walks, electrostatic charges continuously build up on the person body through the contact and separation process that takes place between the person’s shoe sole and the flooring material.
The electrostatic charges start to discharge from the person when he touches a conductive material. That explains the reason why a person would feel a jolt when he touches a conductive door knob in a cold and dry weather.. Static jolt is felt when static electricity of at least 3000 Volt build up in a person body. But a mere 10 Volts can kill a Tunneling Magnetoresistive head(TMR)straight away without the person knowledge.
In any organization, ESD personnel grounding are given the most attention.
There are two common ways where ESD personnel grounding are controlled:
• Wearing an ESD wrist strap
• Wearing an ESD shoes
ESD wrist strap
When wearing an ESD wrist strap, the wearer has to ensure that the wrist strap band is making an intimate contact with his bare skin. This is to ensure the wearer is really bonded to the ground via the wrist strap.
A good wrist strap usually comes with a 1 Megohm +/- 10%, ¼ Watt resistor to protect the wearer from the hazardous current or electrical shock.
The ESD wrist strap is used to drain the electrostatic charges from the wearer body to the ground.
The lower the resistance measured from the wearer to the ground when the ESD wrist strap is in use, the lower the body voltage would be. This is because the electrostatic charges flow faster to the ground when the total wrist strap resistance is lower.
The total wrist strap system resistance when wrist strap is in use has to be less than 35 Megohm to get a body voltage less than 100 Volts.
ESD shoes
Before buying any ESD shoes, the organization has to ensure that the esd shoes are evaluated with the presence of the ESD flooring. This is because the esd shoes and esd flooring has to work hand in hand like husband and wife to ensure full effectiveness.
To get a body voltage less than 100 Volts, the total system resistance from the wearer through the esd shoes and esd flooring to the ground shall be less than 35 Megohm.
If the organization has a total system resistance greater than 35 Megohm but less than 1000 Megohm, this condition is still acceptable as long as the body voltage of a person is less than 100 Volts.
When an organization is dealing with a more sensitive device which can be easily damaged by a 50 Volts human body voltage, then a total system resistance of the ESD personnel grounding device when in use to ground must be less than 10 Megohm.
ESD grounding or ESD bonding reference point
The vital part of an ESD Control Program is the grounding. Grounding provides a path for electrostatic charges to flow to ground.
ESD grounding or ESD bonding reference point is the ground point where ESD Technical elements are connected to. This ESD grounding/bonding system can be any of the following:
• AC equipment ground
• Auxiliary ground
• Equipotential bonding
AC equipment ground:
AC equipment ground is preferred as the ESD grounding/bonding reference point. It is the 3rd terminal of an ac power receptacle. When ESD Technical elements such as wrist strap, floor mat, cart and work surface are connected the AC equipment ground, they are brought to near or to the same electrical potential with other AC powered equipments or tools used within the ESD Protected area or also known as EPA.
When AC equipment ground is used as the ESD grounding system, it has to be verified periodically as defined in the ESD Control program plan.
The followings have to be verified by using an Impedance meter:
• Wiring orientation of the Hot, Neutral and equipment grounding conductor are not reversed.
• The impedance of the equipment grounding conductor from the AC equipment receptacle to the neutral bus in the main service equipment panel shall be less than 1 ohm.
• The neutral and the equipment grounding conductor are not connected at the AC power receptacle.
Auxiliary ground:
An auxiliary ground is basically a separate supplemental grounding conductor used to provide a grounding path for the ESD Technical elements.
Some organizations require the use of an auxiliary ground as their ESD grounding system.
Again, the auxiliary ESD ground has to be verified to ensure its integrity and adequacy as the ESD grounding/bonding reference point.
The resistance between the Auxiliary ground and the AC equipment ground shall be less than 25 ohm.
Equipotential bonding:
When AC equipment ground is not available for example out in the field service area, equipotential bonding system can be used to safely handle ESD sensitive parts.
All the ESD Technical elements, tools and equipments and materials are bonded and connected to the same common connection point. This methodology helps to equalize all the electrostatic charges that present in the total system, and as a result there is no hazard electrical potential difference between the items in the system that could potentially cause ESD damage.
ESD grounding or ESD bonding reference point is the ground point where ESD Technical elements are connected to. This ESD grounding/bonding system can be any of the following:
• AC equipment ground
• Auxiliary ground
• Equipotential bonding
AC equipment ground:
AC equipment ground is preferred as the ESD grounding/bonding reference point. It is the 3rd terminal of an ac power receptacle. When ESD Technical elements such as wrist strap, floor mat, cart and work surface are connected the AC equipment ground, they are brought to near or to the same electrical potential with other AC powered equipments or tools used within the ESD Protected area or also known as EPA.
When AC equipment ground is used as the ESD grounding system, it has to be verified periodically as defined in the ESD Control program plan.
The followings have to be verified by using an Impedance meter:
• Wiring orientation of the Hot, Neutral and equipment grounding conductor are not reversed.
• The impedance of the equipment grounding conductor from the AC equipment receptacle to the neutral bus in the main service equipment panel shall be less than 1 ohm.
• The neutral and the equipment grounding conductor are not connected at the AC power receptacle.
Auxiliary ground:
An auxiliary ground is basically a separate supplemental grounding conductor used to provide a grounding path for the ESD Technical elements.
Some organizations require the use of an auxiliary ground as their ESD grounding system.
Again, the auxiliary ESD ground has to be verified to ensure its integrity and adequacy as the ESD grounding/bonding reference point.
The resistance between the Auxiliary ground and the AC equipment ground shall be less than 25 ohm.
Equipotential bonding:
When AC equipment ground is not available for example out in the field service area, equipotential bonding system can be used to safely handle ESD sensitive parts.
All the ESD Technical elements, tools and equipments and materials are bonded and connected to the same common connection point. This methodology helps to equalize all the electrostatic charges that present in the total system, and as a result there is no hazard electrical potential difference between the items in the system that could potentially cause ESD damage.
ESD Training Plan
While ESD training is necessary for those who set up and maintain the effectiveness of the company ESD Control Program, it is also important for all employees who handle the ESD sensitive items in the organization.
The ESD Coordinator or ESD Control Program Manager can get himself/herself trained on ESD by reliable ESD consultants in the neighborhood or through resources available in the internet.
Some of the ESD consultants available for ESD training and consultancy are:
•Steve Halperin and Associates
His products includes ESD training and seminar, ESD materials evaluation and testing, Facility auditing and evaluation, ESD S20.20 Program design and Product development.
His teams comprises of Ron Gibson and John Kinnear, both are famous ESD S20.20 Training gurus.
•Ted Dangelmayer and Associates
Ted has come out with a team called ESD Dream Team. His team comprises of 4 PhD Experts and 3 Global ESD Program Managers. Ted also wrote a book called ESD Program Management that is widely used by most ESD coordinators across the globe. Famous for Class 0 ESD training program and teams have vast experience in ICs and heads.
•Dr Jeremy Smallwood
Dr Jeremy Smallwood is from England, offering ESD Training and consultancy and Research support in the area of ESD and ignition energy study, ESD test and measurement according to British and International Standards.
•Bob Vermillion
Bob Vermillion is a key technical person in RMV Technology group. RMV is a 3rd Party Independent ESD Investigative Auditing & Testing arm for USA Manufacturing Sites in China, Malaysia, Korea, Taiwan, Philippines, South America and Europe.
Bob is a specialist in ESD packaging and widely recognized across the globe.
The ESD coordinator or ESD Control Program Manager can acquire and improve his/her competency through periodic training either trough External training or through self study from resources available on the internet.
It has become part of the responsibility of ESD Coordinator to establish the ESD Training plan for the organization.
The ESD training plan should specify
• when the ESD training is given
• the techniques or methods used for ESD training
• the ESD training frequency
• the method used to gauge the trainee comprehension and training adequacy
Although the ESD training material contents is at the organization’s discretion, it should address the basic of ESD and controls that the organization wants the employee to follow.
The ESD training materials should also be reviewed from time to time to reflect new changes and controls that complies with the changing ESD requirements by the ESD standards and customer’s requirements.
The ESD Coordinator or ESD Control Program Manager can get himself/herself trained on ESD by reliable ESD consultants in the neighborhood or through resources available in the internet.
Some of the ESD consultants available for ESD training and consultancy are:
•Steve Halperin and Associates
His products includes ESD training and seminar, ESD materials evaluation and testing, Facility auditing and evaluation, ESD S20.20 Program design and Product development.
His teams comprises of Ron Gibson and John Kinnear, both are famous ESD S20.20 Training gurus.
•Ted Dangelmayer and Associates
Ted has come out with a team called ESD Dream Team. His team comprises of 4 PhD Experts and 3 Global ESD Program Managers. Ted also wrote a book called ESD Program Management that is widely used by most ESD coordinators across the globe. Famous for Class 0 ESD training program and teams have vast experience in ICs and heads.
•Dr Jeremy Smallwood
Dr Jeremy Smallwood is from England, offering ESD Training and consultancy and Research support in the area of ESD and ignition energy study, ESD test and measurement according to British and International Standards.
•Bob Vermillion
Bob Vermillion is a key technical person in RMV Technology group. RMV is a 3rd Party Independent ESD Investigative Auditing & Testing arm for USA Manufacturing Sites in China, Malaysia, Korea, Taiwan, Philippines, South America and Europe.
Bob is a specialist in ESD packaging and widely recognized across the globe.
The ESD coordinator or ESD Control Program Manager can acquire and improve his/her competency through periodic training either trough External training or through self study from resources available on the internet.
It has become part of the responsibility of ESD Coordinator to establish the ESD Training plan for the organization.
The ESD training plan should specify
• when the ESD training is given
• the techniques or methods used for ESD training
• the ESD training frequency
• the method used to gauge the trainee comprehension and training adequacy
Although the ESD training material contents is at the organization’s discretion, it should address the basic of ESD and controls that the organization wants the employee to follow.
The ESD training materials should also be reviewed from time to time to reflect new changes and controls that complies with the changing ESD requirements by the ESD standards and customer’s requirements.
ESD Control Program plan requirements
ESD Control program plan basically is a living document which is used by an organization to verify the compliance of the Program against its ESD requirements.
ESD requirements for an organization can be established by referring to ANSI/ESD S20.20 standard. This ANSI/ESD S20.20 standard is applicable to all electronics industry such as Semiconductor Wafer processing fab, Semiconductor Assembly and Test, Printed Circuit Board (PCB) assembly, Disk drive, Flat Panel Display and any other industry which involve in producing or assembling ESD sensitive parts.
As the ESD Control program is established with the intention to protect the ESD sensitive parts from being damaged by Electrostatic discharge (ESD), therefore the most sensitive level of the ESD sensitive parts being handled in the plant must be addressed upfront in the ESD Control program plan.
The ESD sensitivity level of most electronic components can be known by inquiring the information from the Design department or from the Material Data Sheet of the part.
When this information is not available, the organization can set up his ESD control as per the ANSI/ESD S20.20 standard scope requirement to protect ESD sensitive part with ESD sensitivity level equal to or greater than 100 volts HBM.
More stringent ESD requirements are needed for protecting the more sensitive ESD parts.
Besides addressing the protection capability of the ESD Control program, the ESD Control program plan shall also address both the Administrative and Technical requirements that support its provision and protection capability for the most ESD sensitive part that the organization can safely handle.
The ESD Control program administrative requirements include:
• Training
• Compliance Verification
Training plan: Under the Training plan, the organization shall include both its initial and recurrent ESD awareness and prevention training program to all his employee who handle or otherwise come into contact with the ESD sensitive parts. Methodology of ESD training provision shall be defined along with the training frequency.
The organization also needs to define the method used to verify the comprehension of the trainee on the subject being trained and its training adequacy and the method of maintaining the training records.
Compliance verification: Under the Compliance verification plan, the organization is basically verifying the ESD compliance of the controls being set up in the ESD Control program plan. That includes verifying the Technical requirements compliance and other ESD control compliance. The former verification involves measurement monitoring and the latter usually is a non-measurement monitoring process.
The compliance verification activity shall be established and documented, including the technical elements to be verified, the verifying frequency and the measurement control limits, the methods and equipments used during the verification process.
The ESD compliance records shall then be maintained as evidence of conformity to the controls of the ESD control program plan.
The ESD Control program plan technical requirements basically include:
• Grounding/ Equipotential bonding system
• Personnel grounding
• ESD Protected area requirements
• Packaging systems
• Marking
• Equipment
• Handling
Verifying the Technical elements shall be done based on method spelled out in the standards referenced in the ANSI/ESD S20.20 standard.
Tailoring statement must be documented in the ESD control program plan when the method used by the organization differs from those in the standards.
The ESD Control program plan needs to be reviewed periodically to ensure the ESD sensitive parts being handled in the plant is safely protected from esd damage.
ESD requirements for an organization can be established by referring to ANSI/ESD S20.20 standard. This ANSI/ESD S20.20 standard is applicable to all electronics industry such as Semiconductor Wafer processing fab, Semiconductor Assembly and Test, Printed Circuit Board (PCB) assembly, Disk drive, Flat Panel Display and any other industry which involve in producing or assembling ESD sensitive parts.
As the ESD Control program is established with the intention to protect the ESD sensitive parts from being damaged by Electrostatic discharge (ESD), therefore the most sensitive level of the ESD sensitive parts being handled in the plant must be addressed upfront in the ESD Control program plan.
The ESD sensitivity level of most electronic components can be known by inquiring the information from the Design department or from the Material Data Sheet of the part.
When this information is not available, the organization can set up his ESD control as per the ANSI/ESD S20.20 standard scope requirement to protect ESD sensitive part with ESD sensitivity level equal to or greater than 100 volts HBM.
More stringent ESD requirements are needed for protecting the more sensitive ESD parts.
Besides addressing the protection capability of the ESD Control program, the ESD Control program plan shall also address both the Administrative and Technical requirements that support its provision and protection capability for the most ESD sensitive part that the organization can safely handle.
The ESD Control program administrative requirements include:
• Training
• Compliance Verification
Training plan: Under the Training plan, the organization shall include both its initial and recurrent ESD awareness and prevention training program to all his employee who handle or otherwise come into contact with the ESD sensitive parts. Methodology of ESD training provision shall be defined along with the training frequency.
The organization also needs to define the method used to verify the comprehension of the trainee on the subject being trained and its training adequacy and the method of maintaining the training records.
Compliance verification: Under the Compliance verification plan, the organization is basically verifying the ESD compliance of the controls being set up in the ESD Control program plan. That includes verifying the Technical requirements compliance and other ESD control compliance. The former verification involves measurement monitoring and the latter usually is a non-measurement monitoring process.
The compliance verification activity shall be established and documented, including the technical elements to be verified, the verifying frequency and the measurement control limits, the methods and equipments used during the verification process.
The ESD compliance records shall then be maintained as evidence of conformity to the controls of the ESD control program plan.
The ESD Control program plan technical requirements basically include:
• Grounding/ Equipotential bonding system
• Personnel grounding
• ESD Protected area requirements
• Packaging systems
• Marking
• Equipment
• Handling
Verifying the Technical elements shall be done based on method spelled out in the standards referenced in the ANSI/ESD S20.20 standard.
Tailoring statement must be documented in the ESD control program plan when the method used by the organization differs from those in the standards.
The ESD Control program plan needs to be reviewed periodically to ensure the ESD sensitive parts being handled in the plant is safely protected from esd damage.
Subscribe to:
Posts (Atom)
