Method and apparatus for strain monitoring of printed circuit board assemblies
First Claim
1. A printed circuit board assembly comprising:
- a circuit board substrate;
a plurality of mounting points for receiving electrical components carried on the circuit board substrate;
a plurality of electrically conductive pathways carried on the circuit board substrate between mounting points; and
at least one strain detector mounted on the circuit board substrate, the strain detector formed of a non-ductile material;
wherein the strain detector has a portion composed of alumina to provide desired failure of the alumina at an appropriate strain level.
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Accused Products
Abstract
A technique of monitoring strain on a printed circuit board assembly involves the use of a strain detector mounted on a printed circuit board. The strain detector is formed of a non-ductile material. The strain detector has a narrowed portion forming a weak link that has a characteristic of breaking when a critical strain limit is exceeded. The method of monitoring can include visual or electrical inspection. The electrical inspection can include having a strain monitoring device. The strain monitoring device has a timer connected to at least one strain detector and a memory for storing results connected to the timer. The capacitance of at least one of the strain detectors is sampled and any change in capacitance is recorded to the memory. In one embodiment, a time stamp occurs in the memory based on when an electrical property changes across at least one of the strain detectors.
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Citations
16 Claims
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1. A printed circuit board assembly comprising:
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a circuit board substrate; a plurality of mounting points for receiving electrical components carried on the circuit board substrate; a plurality of electrically conductive pathways carried on the circuit board substrate between mounting points; and at least one strain detector mounted on the circuit board substrate, the strain detector formed of a non-ductile material; wherein the strain detector has a portion composed of alumina to provide desired failure of the alumina at an appropriate strain level. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of testing a printed circuit board assembly for failure comprising the following steps:
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providing a printed circuit board; mounting at least one strain detector having a sensing portion formed of a non-ductile material on the printed circuit board; monitoring the sensing portion of the strain detector on the printed circuit board to determine if strain related failure has occurred; wherein monitoring the sensing portion of the strain detector includes determining if failure has occurred at a pre-defined location on a narrowed portion of the sensing portion of the strain detector that forms a weak link in the detector; wherein monitoring includes electrically inspecting the sensing portion to determine if an electrical property of the strain detector has changed mounting at least one integrated circuit package to the printed circuit board, the integrated circuit package having a plurality of corners; wherein the step of mounting at least one strain detector comprises mounting at least three strain detectors, each of the strain detectors located in proximity to a corner of the integrated circuit package, the longitudinal axis of the strain detector bisecting the adjacent corner; and wherein the step of observation is done by electronic method comprising the step of providing a strain monitoring device having a timer connected to at least one strain detector and a memory for storing results connected to the timer; sampling the capacitance of at least one of the strain detectors; and recording when the capacitance changes. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A printed circuit board assembly comprising:
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a circuit board substrate; a plurality of mounting points for receiving electrical components carried on the circuit board substrate; a plurality of electrically conductive pathways carried on the circuit board substrate between mounting points; and at least one strain detector mounted on the circuit board substrate, the strain detector formed of a non-ductile material; wherein one of the electrical components is an integrated circuit package having a plurality of corners, and further comprising; at least three strain detectors, each of the strain detectors located in proximity to a corner of the integrated circuit package, the longitudinal axis of the strain detector bisecting the adjacent corner; and a strain monitoring device having a timer connected to at least one strain detector and a memory for storing results connected to the timer. - View Dependent Claims (15, 16)
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Specification