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US 4,287,766 AGranted
Inspection of solder joints by acoustic impedance
AssigneeBattelle Development Corporation
InventorDale Ensminger
Life of this patent
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Abstract
A method for detection of unacceptable solder joints, especially solder pads on printed circuit boards (PCBs), by means of the application of acoustic vibrations over a range of frequencies to the solder joint and observation of the acoustic impedance of the joint as reflected back through the driver to the acoustic generator or through an acoustic detector near the generator to electrical detecting apparatus.
Claims7
A method for qualitatively inspecting the integrity of a solder joint joining first and second conductors comprising
- (a) applying acoustic vibrations to the solder joint over a range of frequencies which includes at least one natural resonant frequency of the solder joint,
- (b) receiving the acoustic vibrations, as modulated thereby, from the solder joint with a receiving transducer converting acoustic vibrations into electrical signals,
- (c) observing the spectral response of the receiving transducer, and
- (d) comparing the spectral response of the receiving transducer with previously determined spectral responses characteristic of either unacceptable or acceptable solder bonds whereby to determine the acceptability of the solder bond.
1 more element
Dependencies are inferred from the claim text.