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78 I-CONNECT007 MAGAZINE I JANUARY 2026 ULTRA-HIGH STAKES Will UHDI Enter the Mainstream for Low- and Mid-volume? The casual observer might think it is easier to make a low-volume product than a high-volume product. However, making anything in low volume means for- going the extensive ramp-ups and process fine-tun- ing that are more easily amortized where high vol- umes are concerned. Why do I note this? Well, UHDI is capital-intensive to introduce and a challenge to shake down a process with limited volumes. But there are signs that, at least in the arena of designs down to 25-micron line widths, that more fabricators are starting to test the waters. As industry knowledge builds, so should the adop- tion. UHDI is long established and shaken down in high-volume markets—phones/tablets, etc.—but the production world they inhabit is far removed from the low-volume specialist market, which now dominates U.S. and European fabrication. Modelling and Measurement Since last addressing this topic at Polar, we have had the chance to build, model, measure electrically, and SEM measure sectioned traces from a low-vol- ume specialist provider. Initial results look positive, provided you de-embed the DC resistance from the traces, which, at a couple of mils or less, look more like resistors than pure conductors. I mused whether we would uncover an as-yet-undetected electrical effect that would make the measurement/modelling scenario more complex than before, but so far, so good. Papers should follow in due course. T H E PU L S E Feature Column BY MARTYN GAUDION, POL AR INSTRUMENTS LTD. Figure 1: A 4-inch, 50 Ohm transmission line could look like 55 Ohms if you fail to de-embed the line resistance.