Abstract:
A scanning acoustic microscope includes a transducer mounted in a cup below a particular elevation capable of producing ultrasonic energy and a coupling fluid source disposed below the particular elevation, which is configured to introduce coupling fluid into the cup. Ultrasonic energy is directed upwardly through coupling fluid disposed between and contacting the transducer and a first surface of a part to be inspected. The part is disposed at the particular elevation such that a second surface of the part is not contacted by coupling fluid during testing.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/304,070, filed Nov. 23, 2011, which claims the benefit of U.S. Provisional Patent Application No. 61/416,610, filed Nov. 23, 2010, which are hereby incorporated by reference herein in their entireties. 
    
    
     REFERENCE REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable 
     SEQUENTIAL LISTING 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a scanning acoustic microscope with an inverted transducer and bubbler functionality for inspecting a part. 
     2. Description of the Background of the Invention 
     U.S. Pat. No. 7,584,664 is entitled “acoustic micro imaging device having at least one balanced linear motor assembly.” U.S. Pat. No. 7,522,780 is entitled “frequency domain processing of scanning acoustic imaging signals.” U.S. Pat. No. 7,395,713 is entitled “tray-fed scanning microscope system and method primarily for immobilizing parts during inspection.” U.S. Pat. No. 7,000,475 is entitled “acoustic micro imaging method and apparatus for capturing 4D acoustic reflection virtual samples.” U.S. Pat. No. 6,981,417 is entitled “scanning acoustic micro imaging method and apparatus for non-rectangular bounded files.” U.S. Pat. No. 6,895,820 is entitled “acoustic micro imaging method and apparatus for capturing 4D acoustic reflection virtual samples.” U.S. Pat. No. 6,890,302 is entitled “frequency domain processing of scanning acoustic imaging signals.” U.S. Pat. No. 6,880,387 is entitled “acoustic micro imaging method providing improved information derivation and visualization.” U.S. Pat. No. 6,460,414 is entitled “automated acoustic micro imaging system and method.” U.S. Pat. No. 6,357,136 is entitled “scanning acoustic microscope system and method for handling small parts.” U.S. Pat. No. 5,684,252 is entitled “method and apparatus for ultrasonic inspection of electronic components.” U.S. Pat. No. 5,600,068 is entitled “controlled-immersion inspection.” U.S. Pat. No. 4,866,986 is entitled “method and system for dual phase scanning acoustic microscopy.” U.S. Pat. No. 4,781,067 is entitled “balanced scanning mechanism.” U.S. Pat. No. 4,518,992 is entitled “acoustic imaging system and method.” U.S. Patent Application Pub. No. 20090095086 is entitled “scanning acoustic microscope with a profilometer function.” U.S. Provisional Application Ser. No. 61/362,131 is entitled “acoustic micro imaging device with a scan while loading feature.” The contents of all of the aforementioned patents, publications and applications are incorporated by reference into this application as if fully set forth herein. 
     SUMMARY OF THE INVENTION 
     According to one aspect, a scanning acoustic microscope includes a transducer mounted in a cup below a particular elevation capable of producing ultrasonic energy, and a coupling fluid source disposed below the particular elevation, which is configured to introduce coupling fluid into the cup. Ultrasonic energy is directed upwardly through coupling fluid disposed between and contacting the transducer and a first surface of a part to be inspected. The part is disposed at the particular elevation and a second surface of the part is not contacted by coupling fluid during testing. 
     According to another aspect, a scanning acoustic microscope includes a transducer mounted in a cup below a particular elevation, and a coupling fluid source disposed below the particular elevation, which is configured to introduce coupling fluid into the cup. The scanning acoustic microscope also includes a pump connected to the cup for pressurizing the coupling fluid before it enters the cup. The scanning acoustic microscope further includes a controller operable to control the transducer and the coupling fluid source during testing such that ultrasonic energy is directed upwardly through coupling fluid disposed between and contacting the transducer and a first surface of a part to be tested. The part is disposed at the particular elevation and a second surface of the part is not contacted by coupling fluid during testing. 
     According to yet another aspect, a method of scanning a part using a scanning acoustic microscope includes the steps of mounting a transducer mounted in a cup below a particular elevation and disposing a coupling fluid source at the particular elevation. The coupling fluid source is configured to introduce coupling fluid into the cup. The method also includes the step of providing a controller for controlling the transducer and the coupling fluid source during testing such that ultrasonic energy is directed upwardly through coupling fluid disposed between and contacting the transducer and a bottom surface of the part to be inspected. The part is disposed at the particular elevation and an upper surface of the part is not contacted by coupling fluid during testing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various examples objects, features and attendant advantages of the present invention will become fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
         FIG. 1A  is a top view of a tray of parts that is designed to support various large microelectronic samples for transport through a scanning acoustic microscope illustrated in the remaining figures; 
         FIG. 1B  is a side view, partly in cross section, of a portion of an embodiment of a scanning acoustic microscope having an inverted transducer and a bubbler functionality; 
         FIG. 2  is a combined diagrammatic view and block diagram showing the transport of coupling fluid through the microscope of  FIG. 1B ; and 
         FIG. 3  is a block diagram showing the electrical connections of the microscope of  FIG. 1B . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiment illustrated. It should be further understood that the title of this section of this specification, namely, “Detailed Description of the Preferred Embodiments” relates to a requirement of the United States Patent Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein. 
     In the present disclosure, the words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular. 
     The description in this document concerns a scanning acoustic microscope having an inverted transducer and a bubbler feature. It is the applicants&#39; intention to preserve the ability to claim a device that includes an inverted transducer and a bubbler feature in combination with none, any, some or all of the other acoustic microscopy features disclosed in the patents and other information incorporated by reference into this document as if fully set forth herein as noted in the background of the invention section. 
       FIG. 1A  is a top view of a tray  10  that is designed to support a number of large microelectronic samples for transport through a scanning acoustic microscope having an inverted transducer and a bubbler feature. In the illustrated embodiment, tray  10  includes four part support areas  12 ,  14 ,  16  and  18  that are defined by ledges  20 ,  22 ,  24  and  26 . A suitable target such as, for example, a microelectronic sample part  36  (shown in  FIG. 1B ) can be supported on the ledges  20 - 26  within the support areas  12 - 18  of the tray  10 . 
       FIG. 1B  is a side, partial cross sectional view of a portion of an embodiment of a scanning acoustic microscope  28  having an inverted transducer and a bubbler functionality. Scanning acoustic microscope  28  includes a waterproof ultrasonic transducer  30  that is designed to emit pulses of ultrasonic energy along axis  32  towards an underside  34  of a sample part  36  that, in use, is generally opposite to the force of gravity. An outer portion of sample part  36  rests on one of the ledges  20 - 26  defining one of the part support areas  12 - 18  in tray  10 . Transducer  30  is connected to suitable control circuitry (not shown) via line  38 . 
     In the illustrated embodiment of the invention, transducer  30  is secured to a bottom surface of a spray cup  40  by, for example, a threaded connection. A water inlet tube  42  is inserted through a side aperture in spray cup  40  with sufficient pressure to allow water (or any other suitable coupling fluid) to fully immerse the transducer  30  inside of spray cup  40  and then travel upwards in a laminar flow (so that bubbles or entrained air do not form in the flow, at lease until the water deflects off the part) and contact the underside  34  of sample part  36 . One aspect of the invention is that, for example, the water pressure is sufficiently high to cause a water flow to cover the distance between the end of the spray cup  40  and the underside  34  of the sample part  36  without blowing the part  36  off of the tray  10  if the water pressure were too high. As discussed in greater detail hereinafter, the appropriate water pressure for a given application can be determined by visual inspection and then set and thereafter automatically applied for subsequent acoustic microscopic inspection of trays of parts as they are moved into and then out of the scanning acoustic microscope  28 . Furthermore, it is may be preferable (depending upon, among other things, coupling fluid supply pressure) that a gap be maintained between the sample part  36  and the spray cup  40  to prevent water pressure from becoming too high such that the water pressure causes the part to be lifted off of the tray  10 . 
     In addition, the sample part  36  may have a critical and non-critical side wherein the critical side cannot get wet. To prevent water from seeping up around the ledges  20 - 26  during the inspection of the non-critical side, a fan or air knife can be used to blow air toward the critical side of the sample part  36 . The fan or air knife is preferably located above the tray  10  and scanning microscope  28  and may be of sufficient capacity to generate a stream of air that covers the entire tray  10 . Alternatively, the fan or air knife may cover only a single part  36  or portion of a part, for example the edges(s) of a part  36 , as desired. The fan or knife blower may also be used to maintain the sample part  36  in place if the pressure of the water flow increases. 
     Another feature of the invention disclosed herein involves the utilization of a drain saucer  43  that, in an exemplary embodiment of the invention, is connected to an outer and lower external surface of spray cup  40 . The drain saucer  43  includes a raised outer rim  44  that is sufficiently wide to be able to capture all of the water emitted from the spray cup as it splashes off of the sample part  36  and the tray  10  and falls back towards the drain saucer  43  due to the force of gravity. A drain tube  46  is inserted in an aperture formed in a bottom portion of drain saucer  43  that is shaped so that all water caught by the drain saucer  43  is directed towards the drain tube  46 . 
       FIG. 2  is a schematic diagram showing the transport of water through the scanning acoustic microscope  28 . An inlet pump  48  draws water from reservoir  50  via tube  52 , pressurizes the water to a suitable level, and then provides the pressurized water to spray cup  40  via tube  42 . A drain pump  54  draws water from the drain saucer  43  via drain tube  46  and then provides the collected water back to reservoir  50  via tube  56 . 
       FIG. 3  is a schematic diagram showing the electrical connections of the scanning acoustic microscope  28 . The transducer assembly  58  includes, in the illustrated embodiment, the transducer  30 , the spray cup  40  and the drain saucer  43  shown in  FIG. 1B . Electrical signals between, to, and from the transducer  30  to the controller  60  pass along line  38 . Controller is electrically connected to x, y, z stage drivers  62  via line  64  so that the x, y, z stage drives can cause transducer assembly  58  to be moved in operative relation with respect to the tray  10  by means of actuators  66  to allow for non-destructive testing of the samples on tray  10  to take place. For example, this action can cause transducer  10  to be moved in an x-y raster scan of each sample. 
     Controller  60  also is electrically connected to pumps  48  and  54  via lines  68  and  70 . The pumps  48  and  54  are turned on and off as needed for non-destructive testing purposes of samples disposed on the tray  10 . Information about the scanning process and the scan results are caused to be shown on the display  74  by controller  60 . For example, both time domain and frequency domain images of a particular sample can be appropriately color coded and then shown to an operator for analysis. Controller  60  is electrically connected to a memory  72  so that, if desired, data for scans can be stored for later analysis or retrieved therefrom and transmitted to others via suitable transport (e.g., email or a memory stick). 
     INDUSTRIAL APPLICABILITY 
     Numerous modifications to the present invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is presented for the purpose of enabling those skilled in the art to make and use the invention and to teach the best mode of carrying out same. The exclusive rights to all modifications which come within the scope of the appended claims are reserved.