PCB Drills & Throughplating

Printed Circuit Board drill tool and throughplating

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

Type	Smallest Ø	Largest Ø	Max. aspect ratio
Type	Drill hole npth	Smallest Ø	200µm	Largest Ø	6,0mm (larger = milling)	Max. aspect ratio	1:10 (rfq 1:12)
Type	Drill hole pth	Smallest Ø	75µm*	Largest Ø	6,0mm	Max. aspect ratio	1:12
Type	Blind via**	Smallest Ø	75µm*	Largest Ø	0,4mm	Max. aspect ratio	1:1 (rfq 1:1,2)
Type	Buried via	Smallest Ø	75µm*	Largest Ø	0,4mm	Max. aspect ratio	1:12

_{* Final diameter after surface finishing!
** Not possible with HAL surface!}

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 1:12, for blind vias 1:1,2.

Sample aspect ratios

Material thickness	drill-Ø min	final-Ø min.*
Material thickness	6,0mm	drill-Ø min	600µm	final-Ø min.*	550µm
Material thickness	3,0mm	drill-Ø min	300µm	final-Ø min.*	250µm
Material thickness	2,0mm	drill-Ø min	200µm	final-Ø min.*	150µm

_{* Final diameter after through-plating}

Tooling / assembly holes (npth)

Tooling or assembly holes (normally with diam. = 3.05mm) should be placed in the same drilling program as pth drill holes, by the customer. Thus, there are no additional tolerances for re-placement into the drill- / milling machine.

Component holes

For manufacturing reasons, component holes are drilled larger than the final diameter defined by you (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!