Drying and gas or vapor contact with solids – Apparatus – For diverse operations on treated material
Reexamination Certificate
2000-10-12
2002-03-19
Walberg, Teresa (Department: 3742)
Drying and gas or vapor contact with solids
Apparatus
For diverse operations on treated material
C073S618000, C073S620000
Reexamination Certificate
active
06357136
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to scanning acoustic microscopes, commonly abbreviated “SAMs”, used in the non-destructive testing of microcircuit parts, and is addressed specifically to a novel system for enhancing the capability of such systems in handling the parts under test.
A scanning acoustic microscope typically has an ultrasonic beam generator that is traversed rapidly back and forth over a part under test. To traverse the entire part, either the beam generator is scanned in two dimensions, or in one dimension, as the part is translated through the beam in the orthogonal dimension.
The image output of the scanning acoustic microscope is employed for the non-destructive analysis of the internal physical characteristics of the part. Operating at a very high frequency, the scanning acoustic microscope is able to penetrate through the part surface and image microscopic internal features in solids such as metals, ceramics, polymers, and composites. Typical components tested include microelectronic components such as integrated circuits (IC's), multi-layer ceramic capacitors, and multi-chip modules. Such components are commonly carried to the scanning station in trays known in the art as JEDEC trays. Faults typical of the parts tested include delaminations, cracks, tilts of discrete layers, disbonds, underfill coverage, and voiding.
It is a characteristic of high-frequency ultrasound that, while able to penetrate solids such as those described, high frequency ultrasound beams cannot pass through an air gap between the ultrasound beam generator and the part under test without severe attenuation. A fluid medium is therefore used to couple the high-frequency output of the scanning head of the ultrasonic beam generator to the part. The fluid medium is usually water, although alcohol and other fluids may be used. In one common approach, a coupling fluid is dispensed in a stream which embraces the ultrasonic beam.
It is the inevitable design trend in microelectronics that parts such as IC's are getting ever smaller. And as they diminish in size, the parts become more difficult to handle and manipulate, especially when tested in a production environment. In particular, a coupling fluid stream is very apt to agitate and dislodge such small parts from the trays as they move through the SAM.
U.S. Pat. No. 5,684,252 to Kessler et al, of common ownership herewith, shows a tray-fed SAM system in which trays of parts are each paired with an open mesh screen to hold the parts in the trays as they pass through the scanning station. The screens are removed from the trays after the scanning operation has been completed. This technique suffers from a requirement for a large number of screens of various sizes and configurations to accommodate different tray sizes and configurations. The screens represent an added capital and maintenance expense, and their handling a labor cost and delay.
OBJECTS OF THE INVENTION
It is an object of the invention to enhance the capability of a scanning acoustic microscope to acoustically inspect very small microelectronic ICs and other parts.
It is yet another object of the invention to provide an improved tray-scanning SAM station for handling trays of small, loosely held parts in a testing environment.
It is a more specific object of the invention to provide means and method for preventing the dislodgment of small parts from trays inspected in a SAM, or by a subsequent drying process.
It is an object of the invention to prevent dislodging of very small, loosely held parts from the trays by the turbulence in the coupling fluid dispensed by the scanning head in its traverse of the trays.
It is another object to provide means for re-nesting partially dislodged parts in the trays as they pass through a scanning station.
REFERENCES:
patent: 3737573 (1973-06-01), Kessler
patent: 3790281 (1974-02-01), Kessler et al.
patent: 3850027 (1974-11-01), Nakanishi et al.
patent: 3886793 (1975-06-01), Cramer et al.
patent: 3898839 (1975-08-01), White
patent: 4008602 (1977-02-01), Love
patent: 4012951 (1977-03-01), Kessler
patent: 4208915 (1980-06-01), Edwards
patent: 4332016 (1982-05-01), Bernsten
patent: 4518992 (1985-05-01), Kessler et al.
patent: 5077695 (1991-12-01), Khuri-Yakub et al.
patent: 5431054 (1995-07-01), Reeves et al.
patent: 5600068 (1997-02-01), Kessler et al.
patent: 5684252 (1997-11-01), Kesser et al.
Erickson Daniel M.
Schackmuth Bryan P.
Coult John H.
Dahbour Fadi H.
Sonoscan, Inc.
Walberg Teresa
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