A unique differentiation in your data between plated-through holes (PTH) and non plated- through holes (npth) is of fundamental importance!
This means that you must, additional to your Gerber data, output a separate drilling program for pth- and npth drill holes, e.g. as Excellon or Sieb&Meyer data. This applies also to press-fit technology and blind and buried vias in multilayers. ODB++ data contain the necessary information automatically!
Component holes need the accurate hole diamater, vias may have a smaller final diameter due to electroplating (plated through) and PCB surface. Basically, we assume holes < 0,5mm are vias.
Attention:
- Please always specify the final hole diameter within the PCB data.
- Hole diameter ≥ 0,5mm will be final diameters.
- Component holes ≤ 0,4mm need to be specified in the order!
- Component holes ≤ 0,6mm must be manufactured with a chemical surface, otherwise these holes will be filled with tin during the HAL process!
Producible hole diameters
Holes with Ø smaller than 0,2mm have a low machining speed (= surcharge).
| Processing | Smallest Ø | Largest Ø | Max. aspect ratio |
|---|---|---|---|
| Laser drilling | 0,075mm | - | 1:1 (rfq 1:1,2) |
| Drilling | 0,1mm | 5,9mm (larger = milling) | 1:10 (rfq 1:20) |
| Milling* | 6,0mm | unlimited | - |
Aspect ratio
The aspect ratio indicates the relationship between the technically producible final diameter depending on the material thickness. Multi-CB can produce aspect ratios up to a maximum of 1:10 (rfq 1:20), for blind vias 1:1 (rfq 1:1,2).
Drilling tools are available in 0.05mm steps. For odd values, round up to the nearest 0.05mm.
Sample aspect ratios
| Material thickness | drill-Ø min. w/ aspect ratio 1:10 | drill-Ø min. w/ aspect ratio 1:20* |
|---|---|---|
| 6,0mm | 0,6mm | 0,3mm |
| 2,4mm | 0,25mm | 0,15mm |
| 1,55mm | 0,15mm | 0,1mm |
| 1,0mm | 0,1mm | 0,1mm |
| 0,8mm | 0,1mm | 0,1mm |
PTH Component holes
For manufacturing reasons, PTH component holes are drilled larger than the final diameter defined by you. The final diameter is only achieved after plating.
You should design the annular rings as large as possible (annular ring ≥ 125µm). It is normally advisable to select the hole diameter in the upper tolerance region of the corresponding part.
Attention:
- Please specify component holes ≤ 0,4mm with your order!
- Component holes ≤ 0,6mm must be manufactured with a chemical surface, otherwise these holes will be filled with tin during the HAL process!