Machine model numbers get written on enquiries far more often than they decide the answer. What actually decides it is the machine class, the stack it carries and the pressure foot it uses — start from what the backup board does in the stack, then narrow the grade with the selection route.
An enquiry that opens with a machine model is a good enquiry, because it tells us the spindle class and the stack. It is not, on its own, enough to name a grade. The same model runs different stacks at different plants, and the grade follows the stack. This page sets out what the machine tells us, what it does not, and the six numbers that close the gap.
Two plants with the same machine can need different backup boards for the same board design, because the decision is driven by stack height, panels per stack, hole size and the pressure foot, not by the badge on the enclosure. Conversely, two different machines at similar spindle speeds, feeding similar stacks, usually land on the same grade family.
So the useful question is not “what do you recommend for machine X” but “what does this stack need”. The machine tells us the second half of that answer: how much support the stack gets, and how much the tool can be trusted not to wander.
| Machine class | Typical stack | What the material has to do | What fails first |
|---|---|---|---|
| High-speed mechanical CNC with pressure foot | 2–4 panels plus entry and backup, 0.2–0.35 mm holes | Hold a flat, stable surface under the foot; resist compression over a long hit count | Backup compresses or shifts, and positional accuracy drifts before burr does |
| Standard mechanical CNC, light stack | 1–2 panels, 0.3 mm and above | Deliver a clean exit with a cost-effective grade | Exit burr and hole-wall roughness, not position |
| Mechanical line running thick copper | Heavy copper, fewer panels, higher heat | Carry heat away and keep the exit flat as the bit wears | Bit wear accelerates and burr rises through the run rather than between runs |
| Laser or hybrid HDI line | Microvia, thin dielectric, no mechanical entry on the laser pass | Support the panel during the mechanical steps around the laser pass | Particle embedment and handling damage, not drill burr |
Notice that in three of the four rows the failure mode is not the one people ask about. Only the second row fails on burr first; the others fail earlier, on position or on heat. That is also why a grade that fixed a burr problem on one line can make no measurable difference on another.
Send these and the recommendation stops being generic.
With those six, the grade family usually narrows to two or three candidates, and a sample decides between them. Without them, any recommendation is a guess dressed as expertise.
Brand is a weak signal and a useful one at the same time. It is weak because the same brand spans several machine generations with very different spindle behaviour. It is useful because it tells us which support and consumable ecosystem the plant is used to, and therefore which questions they already know how to answer.
| What the brand hints at | What we then ask |
|---|---|
| High-rpm spindle, pressure foot controlled | Foot diameter against the smallest pad pitch, and whether the stack is pinned or taped |
| Older controller, fixed depth referencing | Where Z is zeroed, and whether board thickness variation is compensated |
| Line configured for back-drilling | Depth measurement method and the stub tolerance they can hold |
| Mixed fleet, several generations | Which machine runs the critical code, since that is the one the grade has to suit |
We deliberately do not publish a model-to-grade table. A table like that looks authoritative and is wrong for most plants, because it ignores the stack. What we do instead is map the machine plus the six numbers against sheets we already run, and say plainly which part is measured and which part is inference.
If the question is which grade family to start from, the backup board selector narrows it by hole size and board type. If it is how much room the stack has, the stack height calculator gives the thickness budget. The commercial side — sheet price, MOQ tiers and what a landed cost sheet has to contain — is in price, MOQ and landed cost. Where the stack-height question is really a throughput question, the drilling throughput calculator scores panels per hour against the added risk of the taller stack. If the limit is strokes per shift rather than panels per stroke, the drilling cycle time calculator converts hit count and stack into minutes per panel.
For the material behind each grade, the profiles are in HDF, melamine laminate and UV melamine. If the failure you are chasing is positional rather than a hole-quality problem, hole position accuracy sets out the stack-side causes.
We can narrow it to two or three candidates, but not name one from the model alone. The same machine runs different stacks at different plants, and the stack decides the grade. Send the six numbers on this page and the recommendation becomes specific.
Not directly. Higher speed changes heat and wear, which changes what the exit side sees over a long run. The harder question is whether the grade holds its flatness and density through the run, which is a stability question rather than a hardness one.
Then the stack has to provide its own stability, and the backup grade becomes more important rather than less. It also raises the value of pinning or taping the stack, which is a process change rather than a material one.
Yes. On a back-drill pass the depth is referenced from the drilled surface, so flatness and thickness consistency matter more than burr behaviour. The design-side requirements are in the back-drill design rules page.