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The use of flying probe testers has become increasingly popular in recent times, mainly due to the affordability of the equipment and also the reduced cost of testing, as no dedicated or “bed of nails” fixture is required. When using flying probes to test military product, one must be diligent to make sure the test method is allowable. Grid test machines provide full net to net testing for isolation of all nets and full continuity of individual nets. This is referred to as full simultaneous test. When a flying probe is used there are two modes of operation: Direct or indirect.
When a direct test is used the machine will test every board in resistance mode, meaning that every net will be resistively tested for both opens and shorts. Each board will take the same time to test. When the isolation (shorts) test is performed, nets will be tested using an adjacency window. This is different than a bed of nails whereby which each net is tested simultaneously to all other nets using the voltage and isolation resistance thresholds. With a flying probe only nets within the adjacency window are tested to others. Industry accepted practice for this adjacency window is 0.050” (1.27 mm). Also to be considered is the type of adjacency used. Standard practice is X,Y adjacency or “line of sight,” meaning only on the same layer. If Z-axis adjacency is added, the adjacency window becomes three-dimensional and isolation testing is done not only on the same layer, but within the adjacency window on layers above and below.
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Editor's Note: This column originally appeared in the June 2014 issue of The PCB Magazine.
Nolan Johnson, I-Connect007
In the news this week we found a synchrony of topics. Much of the world is aware of the speaking points from U.S. President Joe Biden’s State of the Union address this past Tuesday. In that speech, President Biden talked prominently about U.S. legislation in process to bring more technology manufacturing back to the states. In fact, Intel CEO Pat Gelsinger was not only an invited guest, but was referred to directly in the speech as a positive example. I can only assume that President Biden meant that moment to be a motivator for other CEOs in the industry.
Pete Starkey, I-Connect007
Continuing the highly successful series of EIPC’s Technical Snapshots, and featuring a programme that attracted a record attendance, the 14th online event was held on January 19. The opening presentation came from the ever-cheerful Didrik Bech, of Elmatica, who promised to provide thoughts and ideas about how to secure the supply chain to ensure compliance, not only to reduce the risks but also to increase the opportunities. Stan Heltzel from ESA Materials and Processes Section in the Netherlands gave a fascinating detailed insight into ESA’s approach to microvia reliability. And Liisa Hakola, senior scientist and project manager at the VTT Technical Research Centre of Finland gave the final presentation on how sustainability creates new opportunities for electronics industry.
Dan Beaulieu, D.B. Management Group
It’s always great to see two very good companies form a mutually beneficial alliance. I was lucky enough to watch this particular strategic partnership come to fruition this year between RBP Chemical and Schlötter. I wanted to talk to both companies, so I sat down with Matthias Hampel, global executive representative-PCB and electronics at Schlötter, and Ernest Litynski, president of RBP Chemical Technology, to get the inside story.