Production Board Test
This FAQ answers frequently asked questions about the Framescan vectorless test techniques that are used for detecting open pins on Teradyne TestStation in-circuit test systems.
Framescan is a vectorless test technique that was originally developed by Teradyne for detecting open pins on component packages and connectors. Framescan uses a capacitive test technique that tests for open pins by applying an AC signal to a node on an un-powered printed circuit board and measuring the voltage that is coupled to a plate that is positioned in close proximity to the component package or connector that is being tested.
The Framescan software automatically learns the voltages that are coupled to the capacitive plate for each pin and sets appropriate voltage thresholds. During production testing, any pins that fall below the minimum learned voltage thresholds are reported as open.
The capacitive opens technique is fast to implement, provides precise pin diagnostics, and does not require the creation of complicated test vectors.
Framescan FX 2.0 is Teradyne’s 3rd generation vectorless test solution designed with advanced measurement hardware and improved software algorithms that was developed to improve the ability to measure opens reliably on today’s smaller device packages and connector technologies that are being used on new board designs. The hardware improvements include a new low noise amplifier that increases the front-end gain of the active probe to minimize the effects of noise components at other stages in the measurement circuit and a new multiplexer/selector board designed with low noise circuit devices and a circuit topology that rejects common mode noise. The software improvements include an automatic precision mode that increases the number of measurement samples for low measurement signals and a new threshold setting algorithm that is optimized for increased fault coverage and the elimination of false positive and false failure diagnostic results.
Framescan FX 2.0 uses a different Amplifier and Selector board than the previous generation. The Framescan FX amplifier has the Teradyne logo and silkscreen to identify the positive and negative terminals of the amplifier. The Framescan FX amplifier also has a conformal coating to improve its noise immunity.
The Selector board routes the signals from the sensor plate/amplifiers in the fixture to the tester’s voltmeter. The Selector board requires three separate voltages to power-up (the TestStation system must be configured with the Fixed Power Supply option). The newer Framescan FX 2.0 Selector Board uses different components and the difference in component placement is significant between the two board types.
Teradyne recommends that all new fixture designs use the latest Framescan FX 2.0 Selector board and FX Amplifiers because they provide improved noise rejection, increased signal path gain, and higher signal to noise ratio.
Most in-circuit fixture manufacturers keep a stock of Framescan hardware components so that they can quickly satisfy customer requests. You can also order parts directly by contacting your local Teradyne Sales representative.
- Framescan FX 2.0 Kit
- Framescan FX Horizontal 10 Amp Kit – this is a kit of 10 high performance Framescan FX amplifiers with a standard horizontal orientation.
- Framescan FX Vertical 10 Amp Kit – This is a kit of 10 high performance Framescan FX amplifiers with a vertical orientation to make it easier to test very small parts with tight spacing.
- Framescan Sensor .375″ x .475″ (kit of 10 assemblies)
- Framescan Sensor .425″ x .575″ (kit of 10 assemblies)
- Framescan Sensor .500″ x .625″ (kit of 1 assembly)
- Framescan Sensor 1.25″ x 1.25″ (kit of 10 assemblies)
- Framescan Sensor 2.56″ x 2.56″ (kit of 1 assembly)
- INSULATOR, Sheet 5.25″ x 7.25″ (kit of 10 sheets)
The Opens Xpress capacitive opens technique is available as an option on all GR228X and TestStation testers and still remains effective for many device packages and connector components. If manufacturers are developing programs and fixtures that need to run on older GR228X and TestStation non-UltraPin test systems, then Opens Xpress or the original Framescan hardware can be used.
Since the Framescan vectorless technique is capable of measuring smaller signals and is less susceptible to noise in the manufacturing environment, Teradyne recommends that Framescan be used instead of Opens Xpress in most situations.
Teradyne has performed evaluations comparing the capabilities of Opens Xpress, Framescan, and Framescan FX 2.0:
- The active probe plate used by the orginal Framescan technique improved the Signal-to-Noise ratio by more than 3 to 1 compared to the passive probe plate (no amplifier approach that is employed by Opens Xpress.
- The low impedance measurement path of the Framescan hardware is less likely to be affected by noise sources in the manufacturing environment. Using a signal generator as a noise source and placing it close to the measurement probe proved this. The Framescan S/N ratio was only slightly affected by the noise source (reduction of 2dbV: 43dbV to 41dbV) while the effect on the Opens Xpress S/N ratio was much greater (reduction of 46dbV: 50dBV to 4dbV).
- Standard Framescan measurements averaged 2-4 times higher than Opens Xpress measurements (some pins measured greater than 10 times higher with Framescan).
- Standard Framescan measurements with FX amplifier probes averaged 6-7 times higher than Opens Xpress measurements (some pins measured greater than 70 times higher with Framescan FX). The opens pin falut coverage differences between the three techniques had small to large variations depending on the device packaging and lead frame sizes. The Framescan with FX probe vectorless opens test technique had the best pin fault coverage for all package types.
- The higher measurement signal and Signal-to-Noise ratio of the Framescan with FX amplifier technique decreased the likelihood of false failure and false passes. Framescan FX was able to correctly diagnose all the device pins that had open pin faults.
- The new Framescan FX 2.0 Selector board had on average a 2 to 1 improvement in measurement signal, a 2 to 1 improvement in Signal-to-Noise ratio, and a better than 10 to 1 improvement in noise rejection compared to the original Framescan Plus Selector board.
- The Framescan FX 2.0 Selector board also demonstrated the same or better open pin fault coverage compared to the Framescan Plus Selector board.
Existing test programs and fixtures that are using Opens Xpress and Framescan will not be affected by the vectorless test improvements in the new Framescan FX 2.0 software release. These tests will continue to work and users do not have to re-learn their Opens Xpress data or create new POD files.
If you want to take advantage of the new Framescan FX 2.0 software algorithms that are available in software version 6.3.0 and later releases, then you must relearn and create a new POD file to obtain new measurement limits. Re-learning the Framescan tests is fast and simple and can be accomplished in seconds using the Vectorless Test user interface.
- Junctions Xpress and DeltaScan – these techniques detect open pins on semiconductor devices by injecting a signal on a pin and measuring the affect of that signal at another pin on the device. These tests are fast and easy to implement since they do not require any special fixture hardware or wiring. They can only be used on devices that have semiconductor junctions and unlike the capacitive vectorless tests they do not work on connectors and sockets. These junction diode techniques are more susceptible to false failures because they require a reliable low impedance fixture connection, however they can be very effective at supplementing the coverage of pins that are not detected by other techniques.
- Orient Xpress – this is an extension of the Opens Xpress capacitive technique that detects when components are placed on the PCB with an incorrect orientation. Framescan FX does not support the Orient Xpress technique because it requires an active guard instrument setup and Framescan uses a fixed ground guard technique. Mi-soriented components will usually be diagnosed as open pins by Framescan FX.
- Cap Xpress – this also is an extension of the Opens Xpress technique that is able to detect when polarized capacitors are mis-oriented on the PCB. Framescan FX also supports the Cap Xpress feature.
Teradyne has made creation of the Vectorless tests simple and fast. At test generation time, the user simply selects which components they want to test with the vectorless test tools. The fixture generation software then creates a file that the fixture manufacturer can use to assemble the fixture with the appropriate vectorless test hardware.
During debug, the test developer uses a graphical user interface that can automatically learn the measurement values for the vectorless tests in seconds. The user interface also has options that allow the user to customize the tests and view the measurement values.