LPKF ProtoMat 93s Manual
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7.10 Basis material
Technically, it is possible to process all base materials.
However, the most basic phenol resin qualities (FR 2) can adversely affect milling
quality.
Glass fiber reinforced epoxy material (FR 4 or G 10) can be a health hazard due
to the milling dust produced (allergies, risk of cancer). Tool service life is also
substantially reduced.
Attention ! Never work without extractor!
We recommend epoxy material without glass fiber (FR 3). With top milling quality
and a high tool service life, no disadvantages with regard to FR 4 are known other
than a slightly reduced mechanical strength (breakage). This drawback should
not be of any significant importance for prototype boards unless particularly heavy
components are to be mounted. The adhesive quality of the copper on the base
material is slightly reduced which might lead to the removal of smaller pads.
Normally, a total thickness of 1.5 mm and a Cu thickness of 35 µm are used. With
17 µm material even fine milling channels can be engraved at a higher density.
For galvanically through-hole-plated, double-sided PCBs, 5 - 17 µm Cu thickness
is used to prevent an excessively thick copper layer after galvanic copper
application.
With 70 µm material, compromises must be made when setting milling depth. I.e.
a deeper milling depth results in wider milling channels of 0.5 to 0.7 mm.
Special base materials with a thicker copper layer of up to 300 µm can no longer
be machined with the LPKF universal milling cutter. Contour milling cutters or
special tools are needed for this. In these cases, we would ask that you consult us
and send sample material so that tests can be carried out if appropriate.
Teflon materials can be machined, but the following points must be borne in mind:
1. As the material is very soft and therefore often extremely uneven, a constant
milling width often cannot be maintained unless the material is smoothed first.
2. Because the material is so soft, it is not possible to mill such as isolation
tracks as in epoxy material.
