This invention relates to electrostatic discharge (ESD) and apparatus and techniques for minimizing or eliminating ESD, and more specifically, apparatus for use in the grounding of benches, ESD bench mats, carts, shelving, and other equipment to reduce the risks from ESD.
Static electricity is commonly defined as an electrical charge resulting from the imbalance of electrons on the surface of a material. Most people are quite familiar with the everyday effects of static electricity—it is the shock one receives when touching a doorknob after walking across a carpet. The technical name for the electrical shock just described is electrostatic discharge. ESD is technically described as the transfer of electrical charge between bodies—for instance, a human hand and a doorknob—that are at different electrical potentials.
In most everyday situations, ESD can be a bother but rarely a problem. However, the problems resulting from ESD are magnified in industrial settings, where ESD is a major concern. Among the many problems that static discharge can cause are the unintentional ignition of flammable materials, damage to electronic components and systems, and the attraction of contaminants such as charged dust particles in clean room environments. Even centuries ago military forces were aware that ESD could cause the unintentional ignition of black powder. To alleviate this sometimes-catastrophic problem, ESD control measures were used as early as the 14th century to protect black powder stores. Today, many industries—from high tech manufacturing plants to businesses commonly thought of as “smoke stack” industries—are concerned with ESD and its control, since controlling ESD can lead to a safer work environment and reduction or elimination of damage resulting from ESD.
While nearly all industries are or should be concerned with controlling ESD, the concern is most acutely felt by businesses in the electronics industry. To give just a few examples of the damage that ESD can cause in the electronics industry, it can destroy or degrade semiconductor devices by changing operational characteristics. It can cause disruptions to the normal operation of an electronic system—sometimes leading to equipment failure, and in clean rooms it can cause charged particles to adhere tightly to the surface of a silicon wafer, resulting in distinct problems with wafer production and efficiency.
Given these problems and the economic damage that can result from them, control of ESD is a major concern and a complete industry has grown up around the field of ESD control.
A critical component of an ESD control program is dissipating and neutralizing ESD during handling, transporting and storing of ESD sensitive materials.
Some very common ESD protective measures are to use conductive floors, benches, bench and floor mats, wrist straps, containers, storage shelves, and transport carts all connected to a common electrical ground to reduce any build-up of electrical potential between objects or people, thereby reducing the risk of an ESD event. In addition, there are several known ESD grounding devices that are commonly used—some of these are described below and shown in the drawings.
The present invention defines an apparatus for eliminating the risks of ESD. The inventive apparatus easily installs onto an ESD mat, a workbench, or equipment, to provide an ESD ground for the device as well as ground plugs to ground operators or other devices. Unlike prior art ESD mat grounding devices that require drilling or cutting holes to install an attachment snap, the invention attaches directly to the mat without damaging the mat and can quickly and easily be moved to a new location without causing damage to the mat.
The present invention also includes multiple receptacles to attach ground wires and banana plugs and built-in mounting holes as a means to attach to equipment, on or under a workbench or onto nearly any location that requires a ground. If attached to a grounded mat or equipment frame, the present invention can use the mat or equipment ground to provide a grounding point for other devices such as wrist straps or other equipment. Additionally, if the present invention is connected to ground with a grounding wire, it can ground an ungrounded mat or equipment frame as well as provide wrist strap grounds for operators or grounds for other equipment.
Several objects and advantages of the invention described herein and shown in the drawings include but are not limited to:
Other objects and advantages of the invention will be evident upon review of the description and drawings. These include:
A. An ESD grounding apparatus for establishing an electrical pathway from a base that is in electrical contact with a mat to an adaptor for attaching a grounding wire;
B. An ESD grounding apparatus for establishing an electrical pathway from a base that is in electrical contact with a mat to an adaptor for attaching a grounding wire without damaging the integrity of the mat;
C. An ESD grounding apparatus that may be attached to a mat for establishing an electrical pathway from the apparatus to a conductive layer in the mat and for attaching a grounding wire to the apparatus to thereby ground the mat.
D. An ESD grounding apparatus wherein a conductive member makes electrical contact with an electrically conductive layer in the mat and the conductive member includes an electrical connection for attaching a grounding wire to thereby ground the mat.
The invention will be better understood and its numerous objects and advantages will be apparent by reference to the following detailed description of the invention when taken in conjunction with the following drawings in which the series of drawings
Various elements of prior art devices are shown in
Illustrated embodiments of the present invention are shown in
Prior to describing the present invention in detail the known prior art will be described in order to provide some measure of background. In the figures like structures are often identified with the same reference numbers.
Common types of ESD grounding used for work benches, floors, and people in the electronics, laboratories, and other industries are shown in
Conventional ESD mat grounding devices are illustrated in
Work benches 23, bench ESD mats 1, floor ESD mats 24, equipment, and the like such as those in
It is common practice in manufacturing, engineering and lab settings to create flexible workstations that can be easily reconfigured to accommodate different products, tests, or other needs.
Although the prior art mat grounding devices can be removed by un-snapping them from the female snap attached to the mat, there are two problems that are created. The first is that the female snap that remains on the mat is frequently in the way and does not allow items to lie flat on the mat. Placing a heavy item, such as a tester or computer, on top of the snap often damages the snap to the point that it requires replacement, which typically a new hole or several slots to be cut into the mat. Each new hole damages the mat by creating a weak spot in the mat, and it is common to see mats with corners torn or missing. The second problem caused by removing the grounding device is that the mat still requires a ground to be attached in a new location. As a result, yet another grounding snap must be installed, thereby creating more holes in the mat.
The present invention will now be described in detail with reference to the drawings of
Preferred and illustrated embodiment of an ESD grounding apparatus 100 according to the invention shown in
Apparatus 100 comprises a main body 30 and a base 30-A. A slot 30-B is defined in main body 30 between the base 30-A and the upper body section 33 of the main body 30. More specifically, as best seen in
Although the entire apparatus 100 may be electrically conductive, the areas that are required to be conductive would be from each of the receptacles 2 to the base 30-A to define an electrically conductive path from the receptacles to the base. The entire apparatus 100 may be fabricated in a mono-lithic, unitary piece or may be fabricated in separate pieces that are attached to one another with appropriate fasteners or adhesives. For instance, the base 30-A may be fabricated as a first piece and the upper body section 33 may be fabricated as a second piece (which in side elevation would be L-shaped). The base 30-A would be directly attached to the upper body section in the orientation shown in, for example,
The main body 30 is shown with two receptacles 2 on each side of the four-sided body, each receptacle 2 sized appropriately for banana plugs 11 (e.g.,
The bottom layer 1-B of mat 1 is highly conductive. Tensioning screw 31 is effective to clamp the mat and with its highly conductive bottom layer 1-B against the base 30-A and thereby provides a low resistance electrical connection between the bottom layer 1-B of the mat and the base 30-A. Since the base 30-A is electrically connected to the receptacles 2 in the body 30, the base 30-A, the bottom layer 1-B, and the receptacles are electrically connected.
In addition to attaching to an ESD mat 1, auxiliary mounting holes 32 in the base 30-A also provide means to secure the apparatus 100 to nearly any surface or equipment as in
Apparatus 100 is attached to a mat 1 with the edge of the mat in slot 30-B as described above and as shown in the drawings, especially
To ground apparatus 100 by means of a grounded ESD mat 1, attach the apparatus to a grounded mat as shown In
To ground the apparatus 100 by means of a ground wire 3, attach a ground wire 3 by means of banana plug 11 and attach the other end of ground wire 3 to common, electrical, or building ground 4 as shown In
To ground a mat 1 using the apparatus 100, install a grounded apparatus 100 onto any edge of a mat 1 as shown In
To ground an ungrounded conductive material or equipment frame 27 such as in
Unlike the prior art, no snap is required to install the apparatus 100 according to the present invention, allowing the present invention to be installed essentially anywhere around the perimeter of the mat 1. Moreover, unlike the prior art the apparatus 100 does not require the drilling, cutting, or punching of holes in the mat 1, so there is no unused snap 6, 8 or holes 9, 9-A left in the previous location as seen in
To install multiple Preferred Embodiments as shown
To remove apparatus 100 from a mat 1 and install it at a new location on the mat 1 or to move to a different mat 1, the tensioning screw 31 is loosened until the mat 1 may be easily removed from the slot 30-B. To ground an operator's ESD wrist strap 25, connect the banana plug 12 of an ESD wrist strap 25 into one of the receptacles 2 on a grounded Preferred Embodiment as shown in
It will be appreciated that the apparatus 100 as described above may be formed in several different structural configurations. Several different embodiments are described below. A second illustrated embodiment of an apparatus 200 according to the present invention is shown in
Although the entire device can be conductive, the areas that are required to be conductive would be from each of the receptacles 2 to an L-shaped cantilever member 42 that is defined by an upwardly extending segment 43-A that is attached to the main body 46 and a cantilever free end 43-B that defines the base of apparatus 100 and which functions to clamp the mat 1 in a slot 45. The L-shaped cantilever member 42 thus has a first leg 43-B that is defined by the free end and a second leg 43-A that is attached to the main body 40. To have the optional snap 5 electrically connected to the base 42, the main body 40 and the cantilever screw 44 would require conductive material, coating, or inserts as well.
The main body 40 is shown with two receptacles 2 on each side, sized appropriately for a banana plug such as shown as 11 and 12. Slot 45 between the main body 40 and the cantilever base 43-A, as shown in
The cantilever 42 clamps the highly conductive bottom layer 1-B of mat 1 against the base 40 and provides a low resistance electrical connection between the bottom layer 1-B of the mat and the main body 40 and therefore to receptacles 2 in the body 40.
In addition to attaching to an ESD mat 1, auxiliary mounting holes such as holes 32 on the apparatus 100 described above could be added by increasing the width of the cantilever base 43 and adding holes. Because the base cantilever member 42 is electrically conductive and electrically connected to receptacles 2, this apparatus 200 can be grounded by attaching it to a grounded conductive frame 27 as shown in
To install apparatus 200 onto a mat 1, an edge of a mat 1 is fit into slot 45 between the free end 43-B of cantilever member 42 as shown in
To move apparatus 200 to a new location on the mat 1 or to move to a different mat 1, the cantilever screw 44 is loosed until the apparatus can be easily removed from the mat 1.
To ground a mat 1, a ground wire 3 is connected a receptacle 2 by means of banana plug 11 as described above and the other end of ground wire 3 is attached to common, electrical, or building ground 4.
Multiples of this embodiment 200 may be installed in a similar manner to the embodiment 100 described above, and providing a ground for an operator's ESD wrist strap 25 would be done in a similar manner to that described above.
Yet another, third embodiment of an ESD grounding apparatus 300 is shown in
In apparatus 300 a spring clamp 52 is adapted to capture a main body 50 between opposed upper arm 57 and lower arm 59 of the spring clamp 42. The spring clamp is constructed of a resilient material such as spring steel. A handle 53 is attached to the terminal end of each of the upper and lower arms, 57 and 59, and may be constructed from a material such as carbon steel or any material with sufficient strength that the handles can open the spring clamp 52.
Although the entire apparatus 300 can be conductive, the areas that are required to be conductive would be from each of the receptacles 2 of main body 50 to the spring clamp 52.
The main body 50 is shown with two receptacles 2 on each side, sized appropriately for a banana plug such as shown as 11 and 12. The slot 58 between the main body 50 and the lower arm 59 of the spring clamp 52, as shown in
The spring clamp 52 clamps the highly conductive bottom layer 1-B of mat 1 against the main body 50 and provides a low resistance electrical connection between the bottom layer 1-B of the mat and the main body 50 and therefore to receptacles 2 in the main body 50.
In addition to attaching to an ESD mat 1, auxiliary mounting holes such as those on the previously described embodiments may be added by increasing the width of the at least the lower arm 59 of the spring clamp 52 and adding holes. Because the spring clamp 52 is electrically conductive and electrically connected to receptacles 2, this device can be grounded by attaching it to a grounded conductive frame 27 as shown in
In a relaxed position the apparatus 300 is in the configuration shown in
To move apparatus 300 to a new location on the mat 1 or to move to a different mat 1, the handles 53 are moved to the position shown in
To ground a mat 1, a ground wire 3 is inserted into a receptacle 2 by means of banana plug 11 with the opposite end of the ground wire 3 connected to common ground 4, which connects to electrical, or building ground.
Multiples of this apparatus 300 are installed in a similar manner to the preferred embodiment and providing a ground for an operator's ESD wrist strap would be done in a similar manner above.
A fourth embodiment of an ESD grounding apparatus 400 is shown in
Although the entire apparatus 400 can be conductive, the areas that are required to be conductive would be from each of the receptacles 2 to the base 61.
This embodiment is not shown with the optional snap 5, but one could be easily added with an adjustment of the size of either to the base 61 or to the body 60 to allow for the installation.
The main body 60 is shown with two receptacles 2 on each side, sized appropriately for a banana plug such as shown as 11 and 12. The slot 65 between the main body 60 and the base 61, as shown in
The lever nose 64-B clamps the highly conductive bottom layer 1-B of mat 1 against the base 61, which provides a low resistance electrical connection between the bottom layer 1-B of the mat and the base 61 and therefore to the upper part of the base 61 and to the receptacles 2 in the body 60 in the same manner as detailed above with other alternatives.
Like other embodiments described herein, the embodiment shown in
To install the apparatus 400 of the fourth embodiment onto a mat 1, the lever 62 is moved to the open position as shown in
To remove the apparatus 400 from a mat 1, the lever 62 is rotated to the open position as shown in
To ground a mat 1, a ground wire 3 is inserted into a receptacle 2 by means of banana plug 11 and the other end of ground wire 3 to common ground 4, which connects to electrical, or building ground.
Multiples of this embodiment are installed in a similar manner to the embodiment described above and a ground for an operator's ESD wrist strap would be done in a similar manner to that already discussed.
As with the other embodiments, this embodiment would provide grounding points and provide a ground for ungrounded equipment in a similar manner to the embodiment shown in
A final alternative embodiment of an apparatus 500 according to the invention is shown n in
The base 71-A and 71-B is similar to the base 61 of the prior embodiment except that is has been bifurcated in order to allow a continuous ground monitoring system to test to see if a conductive mat is in place between the base left side 71-A and base right side 71-B, and that it is connected to ground 4.
If a shorting wire is connected between one of the receptacles on the left 72-A and receptacles on the right 72-B, this embodiment is essentially the same as the apparatus 400 of the prior embodiment.
The main body 70 should be made of insulative, rather than a conductive material.
This embodiment is not shown with the optional snap 5, but one could be easily added with an adjustment of the size of either to the base 71-A, 71-B, or both and could also be used for an auxiliary ground or for a connection to a ground monitoring system.
In contrast to apparatus 400, with the apparatus 500 the base is bifurcated into 71-A and 71-B, which makes receptacles 72-A and 72-B electrically isolated from one another.
The same method that is used with the apparatus 100 described above is used with apparatus 500 to install, remove, move, or ground apparatus.
To use the apparatus 500 as a mat 1 continuity monitoring connection device for ground a mat 1, install the apparatus to a mat 1 and attach a ground wire 3 into a receptacle 72-A by means of banana plug 11. Attach the other end of ground wire 3 to common ground 4. Attach a cable from the continuity test device to a receptacle 72-B on the other side. The testing device tests from receptacle 72-B through mat 1 to receptacle 72-A to ground 4.
Providing a ground for an operator's ESD wrist strap would be done in a similar manner to the preferred embodiment.
As with the other embodiments, this embodiment would provide grounding points and provide a ground for ungrounded equipment in a similar manner to the embodiment shown in
It will be evident from the foregoing description and drawings that there are numerous modifications that may be made to the ESD grounding apparatus of the invention that fall within the bounds of the invention. Such modifications may include, for example:
A. mounting a conventional snap to the body of any of the embodiments of an ESD grounding apparatus described herein so that the device may be used with conventional snap-to-wire connections;
B. use of other types of plugs and connectors instead of banana plugs in order to establish an electrical connection;
C. in addition to the embodiments specifically described above, other structural and functional approaches to attach the ESD grounding apparatus to a mat, including for example a magnetic attachment;
D. the ESD grounding apparatus defines a body that is clamped or otherwise attached to a mat and which established an electrical connection between a conductive layer in the mat and the body so that a grounding wire attached to the body grounds the mat. There are many different structures equivalent to those described above and shown in the drawings that are functionally equal;
E. with respect to the embodiment of
F. the use of securement members of a different structure from, for example, the threaded screw 31-A of
While the present invention has been described in terms of preferred and illustrated embodiments, it will be appreciated by those of ordinary skill that the spirit and scope of the invention is not limited to those embodiments, but extend to the various modifications and equivalents as defined in the appended claims.
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Number | Date | Country | |
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62062971 | Oct 2014 | US |