The typical way to make printed circuit boards is by buying copper-clad glass-reinforced epoxy circuit boards and etching away part of the copper — either with ferric chloride, with air-regenerated cupric chloride, or with electrolytic etching. Occasionally people will instead use end-mills in milling machines instead, which inevitably cuts into the highly-abrasive GRP board and spreads glass dust. Typically the copper is around 25 microns thick. But what if we could laser-cut the metal instead?
Well, copper is hard to laser-cut. It heats at 24.4 J/mol/°, boils at 2562°, sucks up 300kJ/mol, and from yellow well into the infrared, it reflects more than 90% of incoming light. (It only reflects about 60% of blue light, giving it its characteristic red or orange color.) But all the kinds of blue and ultraviolet lasers I know about are a real pain in the ass. So you’re just about stuck with an extra factor of ten or so in the already-gigantic energy. (Maybe you could avoid the extra factor of ten by pre-oxidizing the surface.)
(Calculating: 2540° · 24.4 J/mol/° + 300kJ/mol ≈ 360kJ/mol; multiply by another factor of ten or so and you need 3.6MJ/mol for copper. At an atomic weight of 63.5 that’s 5.7kJ/g; at a density of 9.0g/cc it's 51.3 J/cc. I’m leaving out heat of fusion because it’s quite small.)
Zinc might seem like a more reasonable metal to laser-cut. It weighs 65.4 g/mol, boils at 907°, heats at 25.5 J/mol/°, weighs 7.1 g/cc, and sucks up 115 kJ/mol to boil, and typically has about 80% reflectance across the VNIR spectrum, with an inconvenient peak in the red, but a very convenient dip well below 70% in the 1μ range. Its conductivity is about a fourth of copper’s, at 59 nΩm to copper’s 17 nΩm, which you’d have to compensate for by making it four times as thick. So you need 885° · 25.5 J/mol/° + 115 kJ/mol ≈ 138 kJ/mol to ablate it, and if you get ⅓ laser efficiency, you need 0.4MJ/mol, an order of magnitude less ablation energy than copper. But then you lose most of that again with the factor of four increased thickness, making laser energy ablate only about two or three times as much circuit board area per joule.
(Or, if your laser pulses are longer time scales, maybe more, because copper conducts heat at 400 W/m/° while zinc only conducts it at 120 W/m/°. But I’m assuming the laser pulses are short enough that this isn’t a consideration.)
Zinc has a major disadvantage for circuit boards: it tends to form zinc whiskers. It may be possible to fix this by alloying it with some other metal, such as copper (forming brass) or tin (forming a sort of pewter).
I don’t know if it’s possible to reduce the boiling point of metals by forming positive-azeotrope alloys from them.
Other candidate metals might include magnesium (1090°), bismuth (1560°), manganese (1962°), indium (2000°), and tin (2270°). Ytterbium (1466°) and thallium (1473°) are too unstable and toxic, thulium is too expensive, and aluminum doesn’t boil until 2470° and is particularly highly reflective.
Other candidate methods for thermal ablation of metal coatings include arc heating, electron-beam heating, and ion-beam heating.