Electricity: electrical systems and devices – Discharging or preventing accumulation of electric charge
Reexamination Certificate
2000-02-09
2003-01-28
Fleming, Fritz (Department: 2836)
Electricity: electrical systems and devices
Discharging or preventing accumulation of electric charge
C361S220000, C439S510000
Reexamination Certificate
active
06512664
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field of electrical connectors. More particularly, this invention relates to a shunt or jumper for connecting pins in computers and components of computers, such as disc drives.
BACKGROUND OF THE INVENTION
Shunts or jumper connectors include a conductive path that is surrounded by an insulative housing. The insulative housing retains a static charge that accumulates and may not dissipate. The insulative housing on some shunts may develop a static charge as high as 2000 volts. Typically, a shunt is connected to a pin or connector on a circuit board when setting up a device. Certain devices or computers have features and options that the purchaser or customer can configure externally. These options are selected by placing a jumper or shunt over a set of pins to enable options or features of the device or computer. The options or features that can be selected are limitless. For example, in a computer a jumper or shunt may be used to select features such as memory size, Central Processing Unit (CPU) clock speed, and other features. In a disc drive, options that are selected might relate to features such as motor delay, write protect, master/slave, or identification bit selection.
Typically, the housing material of shunts is a very good insulator. Charges can be built up on the insulative material due to handling of the shunt. Any handling of an insulator can build up charges. Physical rubbing generates a static charge on the housing material. A static charge can even be produced by rubbing the shunt or jumper on an electrostatic discharge mat. In most instances, a static charge remains on the larger flat sides of the shunt. Once charged, the insulative property of the housing material prevents movement of charge. For example, when a charged shunt or jumper is placed on a grounded stainless steel plate, the charge from the side of the shunt contacting the grounded plate is discharged while the charge from the opposite side remains. The shunt can remain on the grounded plate for hours without movement of the charge from the ungrounded side of the shunt.
FIG. 10
is an isometric view of a shunt
1000
having a non-static dissipative housing
1004
. The shunt
1000
includes a housing
1004
and an electrical conductor
1003
. As shown, static charge, shown as plus symbols (+), accumulates on the housing
1004
. When a shunt is charged, the metal connector
1003
inside the shunt or jumper takes on the opposite charge from the charge on the insulative housing
1004
, as depicted by negative charge signs (−). The opposite charge occurs in response to the field on the housing material. When the jumper or shunt is attached to a set of pins, the static charge, if any, is immediately discharged into the circuit formed. If the metal connector first contacts a ground pin, the static charge is passed to ground. In this instance, no failure occurs. A problem occurs when the metal connector first contacts the microchip or microprocessor side of the circuit formed. When the charge is dissipated in a microprocessor or microchip, failures may occur, especially in microchips with thinner lines or traces which are on close centers.
When a shunt is charged, the metal connector inside the shunt or jumper takes on the opposite charge of the insulative housing. The opposite charge occurs in response to the field on the housing material. When the jumper or shunt is attached to a set of pins, the induced charge on the metal connector is immediately discharged into the circuit formed. If the metal connector first contacts a ground pin, the static charge is passed to ground. In this instance, no failure occurs. The problems occur when the metal connector first contacts the microchip or microprocessor side of the circuit formed. When the charge is dissipated in a microprocessor or microchip, failures may occur, especially in microchips with reduced features sizes (thinner traces and dielectrics, and smaller junctions).
Microchips with reduced features sizes are pervasive in today's electronic devices. In the past, microchips with larger features sizes had less susceptibility to Electro-Static Discharge (ESD) damage. In essence, the microchips with larger feature sizes are sufficiently substantial to withstand an electrostatic discharge caused by a static charge on the housing of a shunt or jumper.
A constant goal of microchip manufacturers is to miniaturize the device by reducing feature sizes. Some microprocessors have in excess of 10,000,000 gates or junctions on a single chip. The miniaturization of electronic components in semiconductor devices, such as the integrated circuits of microchips, results in extremely small feature sizes. In other words, miniaturization of microchips and more specifically the number of features. The small feature sizes make microchips more vulnerable to ESD damage.
Miniaturization of the feature sizes within microchips has reached a point where configuring options using jumpers or shunts have made microchips susceptible to ESD damage.
One solution to the problem is to provide the circuit with filters capable of withstanding an ESD event. The filters pass ESD spikes to ground or absorb the ESD spike before it damages the circuit. Adding filters is contrary to miniaturization of semiconductor devices. Filters and the related connectors require space. The use of filters also adds to the cost of the semiconductor devices or components. Adding filters increases the complexity of circuit design. Increased complexity also makes incorporating changes to a circuit more difficult.
One way to avoid ESD events in the situation where a shunt is going to be used is to place the shunts on circuits in an ionized environment. In the ionized environment, the static charges are neutralized. This solution is fine for a factory, however, many of the users do not have access to such an environment. Many of the users are placing shunts on circuits in a home or work environment, so this is a less than optimal solution.
What is needed is a method or apparatus that prevents an ESD event or lessens the severity of an ESD event resulting from placing a jumper or shunt onto a circuit which includes microprocessors or microchips. If the ESD event can be prevented or lessened, then failures in microchips having small feature sizes will be prevented or much less likely to occur. What is also needed is a method or apparatus that can be used in a home or work environment without resulting in ESD damage.
SUMMARY OF THE INVENTION
A shunt or jumper type electrical connector is disclosed. The electrical connector, includes a housing, made of a near insulator material, such as polybutylene terephthalate. The near insulator material acts as an insulator but has the characteristic of dissipating an electrostatic charge. Thus, rather than maintaining an electrostatic charge on the housing of the shunt for a long period of time, the housing dissipates the electrostatic charge rather quickly. As a result, when the shunt or jumper is placed by the user to select various options or features of an electronic device, the static charge on the housing and induced charge on the electrical contact within the housing is either eliminated or dramatically reduced to a level that will not cause a failure in a microchip or microprocessor.
As previously mentioned, the disclosed shunt connector includes a housing made of a near insulative material, and an electrical contact positioned within the housing of near insulative material. The electrical contact is for connecting two pins in an electrical device. The near insulative material has a resistance to current flow in the presence of voltage and has a surface resistivity that allows sufficient charge movement to dissipate static electrical charges. The housing material for an ESD shunt application must have its surface resistivity range within 10
4
to 10
10
ohms per square. One such housing material is polybutylene terephthalate.
Advantageously, the connection between the shunt housing, and the i
Bork Randy A.
Parson Ron F.
Pushee William F.
Smith Charles H. A.
Ulrich Scott D.
Buenzow Jennifer
Fleming Fritz
LandOfFree
Static dissipative shunt housing does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Static dissipative shunt housing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Static dissipative shunt housing will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3050782