In laser drilling, the shape of the hole follows the shape of the beam. A standard laser beam has a Gaussian intensity profile: energy is concentrated in the centre and tapers off towards the edges. The material in the middle of the spot therefore sees far more energy than the material at its border — and the result is visible in the via. Top hat optics change that profile. Instead of a peak, the beam is shaped into a flat, uniform intensity distribution with a sharply defined edge — a cross-section that looks like a top hat, which is where the name comes from.
For the extremely small blind microvias, that geometry is not a cosmetic matter. The uniform energy distribution treats the target pad more gently, since energy is no longer concentrated in a single hot centre point.
Top hat beam shaping is available as part of our laser drilling systems and can be combined with the laser sources in our portfolio to match the material and the application — from dielectric drilling to copper direct drilling and fine structuring on flexible substrates. Which configuration makes sense depends on the stack-up, the via geometry and the thickness of the copper in the inner layers.
Contact us to know more — our sales team will be glad to advise you.
