System and method for identifying solder joint defects
AssigneeAgilent Technologies, Inc.
InventorTracy Kristine Ragland
Life of this patent
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Abstract
An improved circuit inspection system incorporates an automated measuring technique that accounts for acceptable Z-axis elevation variance across both a printed-circuit device and a mounting surface when making solder-joint pass/fail decisions. The improved solder-joint inspection system applies a near neighbor solder joint diameter error analysis for each solder joint on a printed-circuit device. A near neighbor solder joint diameter error outlier analysis is used to identify solder joint defects with improved accuracy.
Claims47
A method for adapting test thresholds, comprising the following steps:
- acquiring location information for a plurality of solder joints on a printed-circuit device;
- obtaining information indicative of the variation in distance between a mounting surface of the printed-circuit device and a printed-circuit board;
- recording a measurement of a physical property of a plurality of solder joints used to couple the printed-circuit device to the printed-circuit board;
- estimating a range of acceptable measurements for respective solder joints responsive to variation in distance between the mounting surface of the printed-circuit device and the printed-circuit board;
- and
- setting at least one threshold responsive to the range.
A method for identifying solder joint defects, comprising the steps of:
- recording a measurement associated with a plurality of solder joints on a printed-circuit device;
- estimating an expected value for the plurality of solder joints that accounts for acceptable variance in the distance between the mounting surfaces of a printed-circuit device and a printed-circuit board coupled by the solder joints;
- comparing the recorded measurement with the expected value for the plurality of solder joints to generate a respective error value;
- and
- identifying defective solder joints by applying an error value outlier analysis to the plurality of error values.
An improved solder-joint inspection system, comprising:
- means for measuring at least one characteristic of a plurality of solder joints on a printed-circuit device;
- means for computing an expected value for the measured characteristic for each of the plurality of solder joints that varies as a function of distance between the mounting surface of the printed-circuit device and a printed-circuit board;
- and
- means for formulating an error value as a function of the measured characteristic and the expected value for the plurality of solder joints.
A solder-joint defect analysis detection program stored on a computer-readable medium, comprising:
- logic configured to record at least one characteristic of a plurality of solder joints on a printed-circuit device;
- logic configured to determine an expected value for the at least one characteristic for the plurality of solder joints responsive to low frequency change in a solder joint characteristics across the device;
- logic configured to generate an error value from a mathematical combination of the expected value and the recorded characteristic for the plurality of solder joints on the printed-circuit device;
- and
- logic configured to identify error value outliers.
Dependencies are inferred from the claim text.