1. Our CAM systems ALWAYS
2. Drill’s tool increments 0.05mm one each other ( till 6.5mm size): so we convert the drill sizes given in the drill files or tool lists into millimeters and round to the nearest 0.05mm.
Example:
- Drill size of 35mil is converted to 0.889mm and then rounded to 0.9mm.
- Drill size of 26mil is converted to 0.660mm and then rounded to 0.65mm.
3. Separate drill files for plated (PTH) and non-plated (NPTH) holes are kindly suggested. If this is not possible, always specify different tools for PTH and NPTH holes and mark clearly which tools are PTH and which tools are NPTH. When no PTH/NPTH info
For
For
- Non-connected holes without copper pads.
- Non-connected holes where the copper pad size is equal to or smaller than the drill tool size (attention that this is
- Connected holes with a copper pad only on 1 outer side, no connection on any other layer (outer or inner) and no copper pad on the other outer side.
In these last 4
4. Important:
- the nominal hole size could
- the standard diameter size tolerance will be different from other Cu-plated holes.
5. It is to be considered that to produce Cu-plated holes with nominal end size diameter as for drill requirement we are obliged to drill the holes at a larger size prior to
- VIA HOLES –> drilled hole diameter = end size hole diameter + 0.10mm (4mil)
- PTH -> drilled hole diameter = end size hole diameter + 0.15mm (6mil)
- NPTH -> drilled hole diameter = end size hole diameter
Using this rules the tolerances for hole diameter size are:
NPTH -> +0.05mm/-0.1mm (+2mil/-4mil)
PTH with diameter
PTH with diameter
When no tolerances are specified in
Only PcbOnDemand service allows different tolerances but these should be clearly indicated in the mechanical layer and/or drill tool list. Considering the higher cost of this service, our suggestion is that different tolerances have not to be used without a compelling reason.
6. Drilled holes that overlap the board contour can be:
- NPTH holes without copper pads: these NPTH holes will be realized as a part of the board outline ( by routing process).
- PTH holes with copper pads: these will be taken as “plated holes on the board edge” or “Contour Cut PTH drills” and should be clearly indicated in the mechanical layer or one other specific file. Remark: these plated holes cut by the board edge are not available in the PcbSaving service.
7. Overlapping drill holes.
It is kindly requested to not overlap drill holes in the files even if connected to the same electrical net. These could cause broken drill tools and/or wrong roughness of the hole wall: material residual and small pieces of material left behind may cause voids in the Cu plated hole barrels. It is to be kept a minimum hole to hole (
In the case of
8. Annular Rings of oblong pads.
- on the smallest side of the oblong
- on the longest side of the oblong pad (both over or above the hole) the minimum