Method of Detecting Power Shorts On Low Resistance Electronic Parts.
Original Publication Date: 2005-Mar-07
Included in the Prior Art Database: 2005-Mar-07
With the current semiconductor technology level used in IBM large systems, the effective resistance between power and ground is very low( typically less than 0.2 ohms) and this creates a problem in detecting shorts between power planes. Systems have been powered on after the modules have been mounted on the boards resulting in board burns. These board burns have be caused by modules with shorts, shorts caused by the interposer(fuzz buttons), and shorts on the board itself. This is very costly to the company. When the modules are mounted on the circuit boards of the large systems a short condition won't be detected if its higher than 0.2 ohms because that is the effective resistance of a good module. A method is needed to check for these short conditions prior to power on of the board and module assembly(node). Previously no tests were performed because the board and modules were KGD(known good die).
Method of Detecting Power Shorts On Low Resistance Electronic Parts .
The idea is have a tester characterize and test the modules just prior to being used in a node. When the node is being assembled, the tester would test the board for shorts, then have the operator preassemble the node, and using the characterization data, test the module on the board with very tight limits based on the characterization data. If these tests pass, then the tester would let the operator complete assembly and do a final test based on the characterization data done previously. This would catch any shorts on the board, module, and any shorts associated with the interposer(fuzz buttons).
The invention works in the following steps:
MODULE CHARACTERIZATION SECTION:
A. The module shipped from IMD would be placed in a fixture with pogo pins to establish contact with ground, and power pads of the BSM. B. The fixture would be wired to a Multiplexer that connects these pads to a meter that would make measurements sourcing current and reading voltage. C. A sequence of measurements would be performed and the data recorded for the power planes to ground and between power planes. D. This data would be tested to some limits established for this product type to ensure it still doesn't have any shorts that were created in the shipping process. E. When this module is being used to build a node. The node tester would recall this data for parts of its tests.
NODE TESTING SECTION:
A. The board is conne...