The capability extract shows in thirty seconds what runs as standard and what carries a surcharge.
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To the data check →The plated through-hole is the oldest interconnect on the board and still the most common. Two numbers govern it: the diameter, and how deep the plating chemistry has to reach relative to that diameter.
A via is a drilled hole whose wall is chemically activated and then electroplated with copper, joining every layer the hole passes through. The plating has to reach the middle of the hole with enough throwing power to build a continuous barrel, and that is where the aspect ratio comes in: board thickness divided by hole diameter. At 8 : 1 the process is routine; rigid builds are verified up to 14 : 1 on a 0.20 mm hole and 16 : 1 on a 0.25 mm hole, and towards that limit the barrel thins in the centre.
The second constraint is registration. The drill has to land inside the pad on every layer, and layer-to-layer registration is finite. What remains of the pad around the hole is the annular ring, and our standard design rule is at least 125 µm of it, with 75 µm the verified minimum on 18 and 35 µm copper. Undersized pads are the single most common reason a design comes back as a query.
Cheapest, best understood, most robust. Unless density or signal integrity forces something else, a plated through-hole is the right answer.
A via array under a thermal pad is a legitimate heat path into an inner plane — cheaper and often more effective than a specialist material.
Every net is verified in the 100 % electrical test, and barrel quality is verified by microsection on request.
| Parameter | Standard | Advanced | Note |
|---|---|---|---|
| Min. drill Ø | 0.20 mm | 0.10 mm | Mechanical drilling, tolerance ± 0.05 mm |
| Aspect ratio | 8 : 1 | up to 16 : 1 | 14 : 1 at Ø 0.20 mm, 16 : 1 at Ø 0.25 mm; rigid-flex 10 : 1 / 12 : 1 |
| Annular ring | ≥ 125 µm | ≥ 75 µm | Standard design rule; 75 µm verified on 18 and 35 µm copper |
| Barrel copper | ≥ 20 µm | ≥ 25 µm | Average wall thickness, Class 2 / Class 3 |
| Pad Ø | drill + 0.40 mm | drill + 0.35 mm | The rule that decides annular ring |
| Via to via pitch | ≥ 0.65 mm | ≥ 0.50 mm | Centre to centre |
| Copper to hole wall | ≥ 0.25 mm | ≥ 0.20 mm | On layers the via does not connect to |
| Hole tolerance | ± 75 µm | ± 50 µm | Plated final diameter |
Guide values for pre-selection. Binding values are confirmed per project against your data.
The points below are what most often comes back as a query after data review. Settling them before layout freeze saves a loop.
Pad diameter should be the finished hole plus 0.35 mm minimum. Designers who set the pad first and then shrink the drill to fit end up below the annular ring standard.
A 0.2 mm hole is fine in a 1.6 mm board and beyond the 14 : 1 limit in a 3 mm one. The ratio, not the diameter, is what the plating process actually cares about.
Every plane the via passes through without connecting needs an anti-pad. Too tight a clearance risks a short after registration tolerance is consumed.
Paste wicks down the barrel during reflow and starves the joint. If the via must be in the pad, it has to be filled and capped.
0.10 mm is the verified minimum for mechanical drilling, with a tolerance of ± 0.05 mm. From 0.20 mm upwards is the preferred range — below it tool wear and aspect ratio drive the price, and a laser microvia is often the better answer.
Drill breakout. Registration tolerance means the hole never lands perfectly centred; the ring is the margin that keeps the barrel connected to the pad on the worst-case layer.
Yes, and it is one of the cheapest thermal measures available. An array of 0.3 mm vias under a thermal pad, connected to an inner copper plane, moves a surprising amount of heat.
Class 2 covers most industrial and consumer work. Class 3 tightens annular ring and barrel copper and is normal for automotive safety, medical and aerospace. Say which one applies — it changes the acceptance criteria, not the design.
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