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High mass, heat-sinking, lead-free PCBs have met their match.
PACE introduces the PH 100 low profile IR preheater for the most challenging PCBs
The PACE PH100 is a high powered (1600W), non-contact infrared heating system with an ergonomic, low-profile design which permits operators to safely pre-heat PCBs for fast, efficient soldering, rework or repair
Features:
• Sleek, incredibly low working height improves operator comfort and reduces fatigue, perfect for under microscope
• Intuitive 3.5" resistive Touch Screen Display for all operations • Large 300mm x 300mm (11.8" x 11.8") heating area
1-877-882-7223
www.paceworldwide.com
www.us-
tech.com
December, 2016
Reducing the PCB Bone Pile Continued from page 47
l What is the volume of boards to be
tested? l Should a third party handle the responsibility?
Very large boards can eliminate
certain types of test options, such as the use of flying probers. Similarly, boards with a large number of test points may require a vacuum or com- pressed air system to engage the UUT with the test pins. RF boards may require testing within a shielded (Faraday cage) enclosure to protect against electromag- netic influences. High-volt- age boards require addition- al fail-safes and trip switch- es to guard the user from dangerous power supplies or from the UUT itself. In each of these cases, the fix- ture supplier is a valuable friend and can offer advice on many aspects of fixture design, or on whether or not it is possible to use a gener- ic, reconfigurable system.
Choosing Test Equipment
The test fixture itself Soldering, Desoldering and Rework Solutions Since 1958.
is simply the access mecha- nism that allows the user to probe specific test points on the UUT with the required fidelity. On its own it is mostly useless so it should be com- bined with an optimized set of test equipment. Some smaller businesses will try to use the same test equip- ment that the developer used to debug during design. However, most design tools are not made to withstand the rigors of production testing and do not always support production test soft- ware that allows them to be integrat- ed into broader test strategies. Pushing forward with a mismatched test strategy can lead to a confusing and compromising system that may include multiple user interfaces and create a complicated, possibly illogi- cal, test procedure. It might be prefer- able to decide first on the test execu- tive and then select instruments that can be controlled by it. The next decision is to deter-
mine the diagnostics resolution that the process requires, which affects the types of instruments needed. In the earlier flashlight example, the simple functional test of turning it on and off gives a diagnostics resolution of the entire device. But, by using a digital multimeter (DMM),
for
instance, the battery voltage, the switch open and close resistance, the bulb’s impedance, and the continuity of the interconnections could all be measured. The diagnostic resolution is then much higher, allowing for repair and rework rather than scrap- ping the entire product. For a basic (structural) auto-
RoHS
mated test equipment (ATE) system, such as a manufacturing defects ana- lyzer (MDA), only a few simple meas- urements are necessary — voltage, frequency, timer, and continuity across a few hundred channels. Adding pattern generation and detection, i.e. digital I/O channels then allows testing to be extended into the functional domain. The fur- ther addition of JTAG/boundary scan (IEEE Std. 1149.1) interfaces intro- duces possibilities for full device-to- device interconnection testing, mem- ory cluster connection tests, logic
tests, device programming (flash memory, CPLDs), and more. All of these features can be found in JTAG Technologies’ JT 5705/FXT module, an ultra-compact tester. The JT 5705 can provide almost everything neces- sary for the required diagnostic reso- lution. If the application has other requirements, it is easy to select spe- cialized instruments to augment the tester’s capabilities, including oscil- loscopes, RF generators, power meters, timer counters, and matrix switchers. Testers that combine
Mixed-signal I/O module for existing JTAG controllers.
functional and structural test
aspects are commonly known as “combinational testers.” FPGA technology also allows
flexibility in test systems by allowing reconfigurable instruments to be embedded within the fabric of a device and are typically controlled by PXI or JTAG interfaces. JTAG Technologies’ JT 5705 and JT 5112 MIOS units are reconfigurable tester modules that may be controlled and reprogrammed by JTAG. Test instru- ments that can be built include seri- al bus interfaces (SPI, CAN, I2C, Ethernet), DDRx memory interfaces, and others.
Software for Combinational Testers
After selecting the fixture,
instruments and power supplies, the next step is to choose a test executive software solution. Some of the more popular software options include National Instruments, Python, Micro - soft .NET framework, Marvin’s AT - Easy, Keysight VEE, and JTAG Technologies AEX manager. National Instruments offers a
range of options from the ubiquitous LabVIEW to LabWindows/CVI and TestStand. The LabVIEW graphical programming system was originally designed as a tool for research scien- tists but now appeals to many non- programmers in the ATE world. LabVIEW/CVI offers a more conven- tional programmers interface (API) but is not a full implementation of ANSI C. National Instruments soft- ware is well-supported by a host of instrument drivers often written by the instrument vendor. Often known as the engineer’s
programming tool, Python is praised for having the simplicity of BASIC with many of the advanced features and flexibilities of C. Another major attraction is that it is open-source and thus essentially free. PyVISA is a Python “wrapper” that offers easy access to shared DLLs built into the Virtual Instrument Software Archi - tecture specification laid down in the
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