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ARCHIVE >  July 2013 Issue >  Special Features: Test and Measurement > 

Camera-Assisted Automation Enhances Bond Testing
This virtual point-and-click map was created by bond tester software.

Bond testing grows in importance with every advance in semiconductor packaging technology. The bond testing capabilities of many facilities are being challenged to characterize the integrity of interconnections within semiconductor devices with ultrafine pitches, containing stacked die and/or multilayer wire bonds and within hybrid packages containing mixed device technologies with small but critical interconnections. New developments and advances in bond testing technology are needed to keep pace with the requirements for aligning bond load tools, to support high-throughput, automated bond testing that can be performed reliably, repeatably, and cost-effectively in high-volume-production environments.

Bond testing is instrumental to a number of characterization applications for different devices, including for shear testing of small-geometry, on-wafer interconnections, including microbumps, copper pillars, and flip chip devices. Bond testing is also vital for pull-and-shear testing on semiconductor lead frames, including ultrafine-pitch semiconductor devices, stacked die, and multilayer wire bonds, as well as pull-and-shear testing on hybrid microcircuits, including those in automotive packages and high-reliability mixed-technology packages and substrates.

Of critical importance when conducting bond testing is that accuracy and repeatability be maintained throughout the testing process. Full-scale deflection (FSD) of a selected load range should be maintained typically within ±0.1 percent, with a step-back accuracy that is within ±1.0 micron. This high precision positioning and high resolution force capture provide bond testing capability with integrity.

Automated Bond Testing
Automated bond testing can provide tremendous benefits in high-volume production schemes, but a traditional challenge in establishing an automated bond testing system and solution was the time needed to train operators as well as the down test system time lost for testing during the training period. Proper automated bond testing requires, first of all, creation and/or selection of the proper test pattern, and selection by an operator of the correct test markers for the test equipment to optimally recognize the position of a sample to be tested. These steps are subject to operator errors and inaccuracy, and can result in flawed tests and bond testing measurement results.

To overcome these traditional problems in automated bond testing, with knowledge and experience based on an automated bond testing pedigree of more than two decades, Nordson DAGE (www.nordson.com) developed its 4000Plus bond tester platform using the latest camera-assisted automation. The camera-assisted automation system is built around a unique multifunction load cartridge (MFC), making the camera-assisted automation system ideally suited for applications such as pull-and-shear testing of wafer interconnections, lead frames, hybrid microcircuits, or automotive electronic packages. As examples, the standard 4000Plus system can perform shear tests to 500 kg, pull tests to 100 kg, and push tests to 50 kg, operating on a large X-Y stage. The system features ease of programming using fiducial camera assist and vector stage nudge buttons for precise X-Y stage alignment. The 4000Plus system facilitates rapid changeover for a variety of bond testing applications.

Sequential Testing
Sequential testing of bonds or wires is straightforward with programming of bond or wires locations with point-and-click on the first bond and simple point-and-click operation to move to the second and subsequent bond or wire locations. Wire-pull or bond-shear test parameters are displayed on a computer screen and a virtual wire-pull or bond-shear map is created automatically as an engineer or technician begins programming wire positions for bond testing.
These on-screen windows show Paragon support for a multifunction cartridge.


The 4000Plus system's operation is made somewhat simpler, with less downtime for training, as a result of its accompanying software. Its Paragon bond tester software provides a user-friendly interface with semiautomatic test routines, automatic gage repeatability and reproducibility (GR&R) calculations, unique database search engine wizard, and superior data reporting for unsurpassed data accuracy and repeatability.

Test Methodologies
On the 4000Plus bond tester system, test points are programmed with a simple point and click of a computer mouse identifying all bonds within a device to be tested. The system incorporates high-quality light-emitting-diode (LED) illumination on both the bond tester mainframe and the image capture camera to capture the highest-quality images. The brightness of these LED light sources is independently adjusted by means of software-controlled sliders.
This ball shear testing screen shows tri-camera and side camera images.


The 4000Plus bond tester system features a typically large work area, providing an X-Y stage that extends 210 x 300 mm. The large stage area is made easier to use by means of joystick control and independent Z-axis motion with tool rotation joystick control. Independent "nudge" buttons on the 4000Plus keypad enable fine-motion control across the X and Y stages with vector assistance in the alignment process, which is critical for achieving high bond test accuracy.

The camera-assisted automation of the 4000Plus bond tester system, in conjunction with its unique MFC, makes it possible to execute a six-second application changeover from wire-pull to ball-shear functions. The MFC features a built-in "park" position so that all the transducers are protected when not in use.

No Compromises
In spite of its ease of use and operating efficiency, the 4000Plus bond testing system makes no compromises on loads in accordance with industry standards; it executes simple calibration procedures using traceable weights and maintains compliance with industry specifications. The system is directly linked to an external computer control by means of a Universal Serial Bus (USB) connection. The system's dual arm optics mounting limits the effects of induced vibration in typical production test environments.

An important capability of the 4000Plus bond tester system is capturing a post bond tested image for further analysis of failure mode or to record test events in real time for analysis and better understand of the bond characteristics. The camera-assisted automation functionality of the 4000Plus system makes use of the on-board image capture camera (no special pattern recognition system is necessary); once this option is installed, an operator is aided by the enhanced automation capabilities and improved image capture capabilities. For improved image capture quality, the 4000Plus system can be equipped with another option, a tri-camera, side camera, or borescope. The system will also accept a variety of load cartridges for the MFC, including cartridges that provide multiple load functions for semiconductors as well as for hybrid devices.

The bond tester system provides extensive on-board statistical functions as part of its analysis capabilities, including statistical-process-control (SPC) and gauge repeatability and GR&R calculations. The bond tester system's operating system is compatible with Windows 7, Vista, or Windows XP, with output data available in a variety of formats, such as SQL, CSV, RS-232, and PDF formats; in addition, test results can be copied to a computer clip board.

The fine pitches and dimensions of newer semiconductor devices and their packages continue to foster the use of ultrafine pitch devices, stacked die, and multilayer wire bonds, adding to the challenges of systems designed to test these devices. But with a properly equipped bond tester system, supported by camera-assisted automation, bond testing can be performed reliably, efficiently, and accurately even in high-volume production environments.


Contact: Nordson DAGE, 48065 Fremont Blvd., Fremont, CA 94538 510-683-3930 Web:
http://www.nordsondage.com

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