X-ray or gamma ray systems or devices – Specific application – Absorption
Reexamination Certificate
2002-12-10
2004-05-18
Bruce, David V (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Absorption
C378S062000
Reexamination Certificate
active
06738450
ABSTRACT:
TECHNICAL FIELD
The present invention relates in general to classification of objects under inspection, and more particularly to a system and method for cost-effective classification of an object, such as solder joints, in one of a plurality of different classes.
BACKGROUND OF THE INVENTION
A key challenge facing electronics manufacturers is quality analysis of their products. That is, electronics manufacturers typically want to ensure that their products are of high quality both structurally and functionally. Accordingly, certain techniques for testing the quality of electronic products have been developed. Considering the trend toward smaller components, increased manufacturing complexity, new packaging technologies, and higher functionality boards, new challenges continue to arise in quality testing of electronic products. Additionally, electronics manufacturers typically face extreme cost and time pressures such that it becomes important to implement a quality testing technique that does not substantially increase the cost and/or time associated with the manufacturing process. Preferably, the quality testing technique should aid the manufacturer in reducing the cost and/or time associated with the manufacturing process, e.g., by detecting defects in products as early as possible in the manufacturing process to enable timely correction of such defects and/or to avoid wasted time and expense in further manufacturing of a defected part.
One area in which quality analysis is often desired in electronic products is analysis of solder joints included therein. It is important for solder joints to be of an acceptable quality in electronic products to ensure that the soldered components are structurally and functionally sound. That is, it is important for a solder joint to be of good quality to ensure that the soldered component is securely coupled to the board in a structurally sound manner, and it is important for a solder joint to be of good quality to ensure that the soldered component is electrically coupled to the board in a manner that enables communication of electrical signals to/from the component through such solder joint so that the product can function as desired. As the complexity of electronic products increases, the number of solder joints present in such products tends to increase. For example, many high-complexity products have as many as 20,000 or 30,000 solder joints. A defect with any one of the solder joints in a product may result in the product being structurally and/or functionally unacceptable.
Thus, solder joints impact the structural and functional soundness of electronic products, and it is therefore typically desirable to test the quality of such solder joints to ensure that the products are of desired quality. Of course, it is also desirable to have a quality analysis technique that is reliable and does not substantially increase the cost and/or time involved in the manufacturing process. Automated image processing techniques have been used for analyzing the quality of solder joints. For example, automated optical inspection (AOI) and automated X-ray inspection (AXI) techniques have been developed and implemented for analyzing the quality of solder joints in electronic products. An example of an image processing solution for testing the quality of solder joints is provided in the SJ-50 automated optical inspection system commercially available from Agilent Technologies.
An example of a laminography system that may be utilized for electronics inspection is described further in U.S. Pat. No. 6,201,850 entitled “ENHANCED THICKNESS CALIBRATION AND SHADING CORRECTION FOR AUTOMATIC X-RAY INSPECTION”, which is assigned to the assignee of this application and the disclosure of which is hereby incorporated herein by reference. Further examples of laminography systems that may be utilized for electronics inspection are described in the following patents: 1) U.S. Pat. No. 4,926,452 entitled “AUTOMATED LAMINOGRAPHY SYSTEM FOR INSPECTION of ELECTRONICS”, issued to Baker et al.; 2) U.S. Pat. No. 5,097,492 entitled “AUTOMATED LAMINOGRAPHY SYSTEM FOR INSPECTION OF ELECTRONICS”, issued to Baker et al.; 3) U.S. Pat. No. 5,081,656 entitled “AUTOMATED LAMINOGRAPHY SYSTEM FOR INSPECTION OF ELECTRONICS”, issued to Baker et al.; 4) U.S. Pat. No. 5,291,535 entitled “METHOD AND APPARATUS FOR DETECTING EXCESS/INSUFFICIENT SOLDER DEFECTS”, issued to Baker et al.; 5) U.S. Pat. No. 5,621,811 entitled “LEARNING METHOD AND APPARATUS FOR DETECTING AND CONTROLLING SOLDER DEFECTS”, issued to Roder et al; 6) U.S. Pat. No. 5,561,696 “METHOD & APPARATUS FOR INSPECTING ELECTRICAL CONNECTIONS”, issued to Adams et al.; 7) U.S. Pat. No. 5,199,054 entitled “METHOD AND APPARATUS FOR HIGH RESOLUTION INSPECTION OF ELECTRONIC ITEMS”, issued to Adams et al.; 8) U.S. Pat. No. 5,259,012 entitled “LAMINOGRAPHY SYSTEM AND METHOD WITH ELECTROMAGNETICALLY DIRECTED MULTIPATH RADIATION SOURCE”, issued to Baker et al.; 9) U.S. Pat. No. 5,583,904 entitled “CONTINUOUS LINEAR SCAN LAMINOGRAPHY SYSTEM AND METHOD”, issued to Adams; and 10) U.S. Pat. No. 5,687,209 entitled “AUTOMATIC WARP COMPENSATION FOR LAMINOGRAPHIC CIRCUIT BOARD INSPECTION”, issued to Adams. The entirety of each of the above referenced patents is hereby incorporated herein by reference.
Another imaging technique used in inspection systems is known as tomosynthesis. Tomosynthesis is an approximation to laminography in which multiple projections (or views) are acquired and combined. As the number of views becomes large, the resulting combined image generally becomes identical to that obtained using laminography with the same geometry. Tomosynthesis may be performed as an analog method, for example, by superimposing sheets of exposed film. Tomosynthesis may, instead, be performed as a digital method. In digital tomosynthesis, the individual views are divided into pixels, and digitized and combined via computer software. Three-dimensional computed tomography, such as “cone-beam tomography” for example, is another well-known image processing technique that may be used in inspection of an object. Example tomosynthesis (or tomography) systems that have been proposed for use in industrial inspection systems include, as examples, those disclosed in U.S. Pat. No. 6,002,739 entitled “COMPUTED TOMOGRAPHY WITH ITERATIVE RECONSTRUCTION OF THIN CROSS-SECTIONAL PLANES” and U.S. Patent No. 6,178,223 entitled “IMAGE RECONSTRUCTION METHOD AND APPARATUS,” the disclosures of which are hereby incorporated herein by reference in their entirety.
In addition to image processing techniques, various other tests of an electronic product, such as in-circuit tests (ICTs) and function tests (FTs) may be performed for testing the functionality of the electronic product. A common test strategy for high-complexity printed circuit boards (PCBs) is to use a combination of AXI, ICT, and FT in which AXI tests the structural integrity of the solder joints, ICT tests the electrical integrity of the components and PCB, and FT verifies the PCB's performance characteristics. On complex boards, typically about 80 to 90 percent of all defects found are structural or process defects. AXI testing generally provides about 95 percent coverage of the structural defects. Therefore, it is generally advantageous to use AXI before ICT and FT testing of an electronic product as filtering out of those defective products detected with AXI significantly reduces the number of defects arising during ICT and FT. In addition, AXI typically pinpoints the exact location of the defects (e.g., identifies the specific solder joint that is defective), thus enabling the defect to be repaired in a timely and cost-effective manner before undergoing ICT and FT testing.
Generally, an automated inspection system classifies objects (e.g., solder joints) based on measurements taken of the object being inspected. For example, in a manufacturing inspection system, a customary goal is to determine whether a given object of manufacture is either “good” or “bad” (i.e., belongs to a class of good objects or a class
Agilent Technologie,s Inc.
Bruce David V
LandOfFree
System and method for cost-effective classification of an... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System and method for cost-effective classification of an..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System and method for cost-effective classification of an... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3259994