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Miniaturization has created unique challenges for today's new high-tech products. In addition to their shrinking size, products now have hidden features that must be measured and inspected. X-ray systems are being used in many instances to address these issues.
A specific example of this occurs when mounting high density interconnect components on a printed circuit board (PCB). Each of these components can have hundreds of connections that must be connected correctly to the other components on the board. This only can be accomplished through the use of a multi-layer circuit board-a number of very thin PCBs laminated together, insulated from each other-but connected to each other at precise locations through "via holes." In order for this to happen, each of the layers must be precisely aligned one to the other, in some cases up to 80 layers. As can be imagined, the dimensional attributes of each layer are critical as they are subjected to considerable amounts of heat, vacuum and pressure during the lamination process.
Operations Technology Inc. (Blairstown, NJ) created the Optek InnerVision 712XA, the world's first X-ray coordinate measuring machine, in response to these demands. It measures and reports the position of internal coupon pads on the inner layers of these multilayer PCBs, as well as reinforcements and fastener inserts in composite structures, and other such encapsulated or laminated features.
The images and measurements obtained by the InnerVision reveal and quantify offset, skew, stretch, shrink and other distortions that may affect the location of internal details. The data provided allows fabrication processes such as lamination, molding, drilling and machining to be controlled.
No-maintenance precision linear motors position the stage accurately, quietly and quickly. The stage is close-looped to 1/10 micron linear scales for precise positioning. The system combines specialized real-time X-ray imaging with automated positioning and precision video-based metrology capabilities. The result is one of the most sophisticated X-ray inspection and measurement systems available today.
The system uses advanced metrology software to provide a powerful programming environment and a high degree of programming flexibility. The system has versatile video tools such as Line Width, Circle, Center-of-Mass and Buffer that speed the measuring process.
The Microsoft Windows environment is used with on-line help to ease training. "It usually takes two to three days of on-site training for operators to get up to speed," says Rich Amon, president of Optek. "The machine comes with a syllabus and a
factory-trained engineer goes to the company to accomplish the training."
The multitasking Intel Pentium series processor permits rapid feature detection and high-speed transport control. The network capability is standard. Electronic file or printout of dimensional data and images is available for storage or further analysis.
The system reports the position of features allowing optimization of the operator's fabrication process.
Tolerancing to Cartesian, as well as true position, least material condition and maximum material condition is provided. "Tolerancing ensures that the layers are being manufactured and aligned to the proper dimensions," Amon says.
Programs can be automatically created from computer-aided design (CAD) data or by recording steps while manually measuring a part. A large 19-inch LCD color monitor displays metrology data and X-ray images. The system has an adjustable ergonomic workstation including a compact control panel and standard keyboard to maximize operator performance. A massive granite base and cantilever provide superior machine stability. A high-resolution, intensified X-ray camera provides a brilliant X-ray image while a video "spotter" camera guides the operator to the area of interest. Subsurface features can be illuminated with programmable X-ray voltage and current. An array of image processing tools includes Offset, Gain, Integration and Exposure.
A selection of mini-focus and micro-focus X-ray sources is available to handle many substrate compositions and thicknesses. Pneumatic tooling clamps hold samples of various thicknesses securely to the transport system. A dual-stage camera provides two distinctly different magnifications, each of which is pixel calibrated. "Raw circuit boards are a major application that is aided by this type of camera," says Amon. "Because of its measuring capability, it can look at layers on PCBs and ensure proper measurement."
These challenges are not unique to the electronics industry. Other applications are being considered for this equipment as this article goes to press. Steady improvements in X-ray componentry and performance will enable the accomplishment of chores previously thought impossible. The quest to see things that were formally invisible is just beginning.
For more information on
the Optek InnerVision 712XA, contact:
Operations Technology Inc.
P.O. Box 408
Blairstown, NJ 07825
E-mail: firstname.lastname@example.org, URL: www.optek.net
• The system measures and reports the position of internal coupon pads on the inner layers of these multilayer printed circuit boards.
• The system uses advanced metrology software to provide a powerful programming environment and a high degree of programming flexibility.
• Programs can be automatically created from CAD data or by recording steps while manually measuring a part.
• Transports are driven quietly on precision linear ways and air bearings by sophisticated, no-maintenance, balanced linear motors, which are close-looped to 1/10 micron, or 0.000004 inch, precision scales.