The present disclosure relates generally to printed circuit board structures, and more specifically fusible ground plane structures for printed circuit boards.
Electronic controllers, and other electronic devices that utilize printed circuit board (PCB) technology, typically include at least a power plane and a ground plane separated by an insulating material within the PCB. Alternative constructions can include additional power planes and ground planes, with the increasing number of power planes and ground planes dictating a corresponding decrease in the thickness of each layer. Such constructions can experience an error condition where the power plane of the PCB and the ground plane of the PCB are shorted together.
This can occur when capacitors, power integrated circuits (ICs), or any similar components mounted to the PCB experience certain types of faults. When such a fault occurs, it is possible for the PCB to experience a large destruction event due to the substantial current levels passing through the ground plane, and it is easy for thermal damage to propagate through the planes of the PCB due to the high current capacity.
In one exemplary embodiment a printed circuit board includes a ground plane including a fusible region, a power plane isolated from the ground plane by an insulating layer, and at least one circuit component mounted to the ground plane within the fusible region.
In another example of the above described printed circuit board the fusible region is a mesh pad mounted to a solid ground plane body.
Another example of any of the above described printed circuit boards further includes an insulating pad disposed between a majority of the mesh pad and the solid ground plane body.
In another example of any of the above described printed circuit boards the mesh pad is a consistent material configuration.
In another example of any of the above described printed circuit boards the mesh pad includes a first material in a first fusible configuration and a second material in a second non-fusible configuration, and wherein the second material is surrounded by the first material.
In another example of any of the above described printed circuit boards the first material and the second material have a distinct material composition.
In another example of any of the above described printed circuit boards the ground plan includes a mesh grid connected to the insulating layer.
In another example of any of the above described printed circuit boards an entirety of the mesh grid is fusible.
In another example of any of the above described printed circuit boards at least one region of the mesh grid is surrounded by fusible portions of the mesh grid.
In another example of any of the above described printed circuit boards rein the ground plane consists of the mesh grid.
In another example of any of the above described printed circuit boards the fusible region is a mesh grid embedded in a solid ground plane.
In another example of any of the above described printed circuit boards the mesh grid comprises multiple grid lines, and each line of the mesh grid is fusible.
In another example of any of the above described printed circuit boards at least a portion of the mesh grid is non-fusible, and wherein the non-fusible portion is surrounded by a fusible portion of the mesh grid.
Another example of any of the above described printed circuit boards further includes at least one additional power plane and at least one additional ground plane.
An exemplary method for preventing propagation of short circuits on a printed circuit board includes defining a least a portion of a ground plane using a fusible mesh grid, and disconnecting a sub-portion of the fusible mesh grid from a remainder of the ground plane via fuse action when a short circuit is present.
In another example of the above described exemplary method for preventing propagation of short circuits on a printed circuit board defining at least the portion of the ground plane using the fusible mesh grid comprises disposing a mesh grid pad on a solid ground plane body.
In another example of any of the above described exemplary methods for preventing propagation of short circuits on a printed circuit board defining at least a portion of the ground plane using the fusible mesh grid comprises embedding a mesh grid portion within a ground plane body.
In another example of any of the above described exemplary methods for preventing propagation of short circuits on a printed circuit board defining at least the portion of the ground plane using the fusible mesh grid comprises constructing an entirety of the ground plane using the fusible mesh grid.
In another example of any of the above described exemplary methods for preventing propagation of short circuits on a printed circuit board the fusible mesh grid is entirely fusible.
In another example of any of the above described exemplary methods for preventing propagation of short circuits on a printed circuit board the fusible mesh grid includes an exterior circumference, and the exterior circumference is fusible.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
When a short circuit occurs between the ground layer 2 and the power layer 3, large amounts of current pass through the power layer 3 to the ground layer 2. The large amounts of current, in turn, generate large amounts of heat that can damage or destroy large sections of the PCB 1 if they are allowed to propagate. Short circuits, such as those described herein, can occur via a fault in a power component or due to mechanical stresses on the PCB 1. In the event of mechanical stresses, the fault can occur even absent the presence of the circuit components 5.
In order to mitigate the damage caused when a short between the ground layer 2 and the power layer 3 occurs, the conventional solid ground layer 2 can be entirely, or partially, replaced with a mesh grid when the mesh is configured to operate as a fuse and open (disconnect) when a high current occurs, while still maintaining high EMC efficiency. This configuration is referred to as a fusible mesh grid. In another example, the fusible mesh grid can be applied to the solid ground layer 2, with circuit components 5 mounted to the fusible mesh grid.
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In some examples, the entirety of the mesh grid 21, 31, 41 can be constructed of a single material, with the material being disposed on the ground plan in a manner that will fuse when excess current is passed through the material. In alternate examples, portions of the mesh can be non-fusible, and only segments surrounding select circuit components can be constructed of the fusible material or in the fusible configuration.
Further, it is appreciated that the alternate examples can be used independently or in conjunction with each other in any given embodiment, and the ground plane constructions are not mutually exclusive.
It is further understood that any of the above described concepts can be used alone or in combination with any or all of the other above described concepts. Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
This application claims priority to U.S. Provisional Patent Application No. 62/785,793 filed on Dec. 28, 2018.
Number | Date | Country | |
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62785793 | Dec 2018 | US |