Featured Snippet: Hole Density (holes/cm2) = Holes / PanelArea(cm2)
Free PCB panel hole density calculator. Compute holes per cm2 / per in2 from hole count and panel area, and classify low/medium/high density. the material grades these numbers apply to carries the material data the model assumes; the selection guide explains how to choose between grades.
Suitable for:
Compute hole density.
| Hole density | -- /cm2 |
| In imperial | -- /in2 |
| Class | -- |
Use routed (usable) panel area, not raw sheet, for a true density.
Hole density (holes per unit area, or CPP) tells you how hole-rich a panel is - directly driving drilling time, hit count demand and micro-via strategy. This tool converts your hole count and panel area into holes/cm2 and holes/in2 and classifies the density.
Low-density panels drill fast on standard bits; high-density HDI panels are hole-rich and push toward laser drilling for micro-vias and toward higher hit count demand. Knowing CPP helps you size cycle time and choose entry/backup boards. See our lubricant aluminum page.
| Material | Throughput Impact | Hole Quality | Cost per Panel |
|---|---|---|---|
| UV Melamine backup board | High hit count | Excellent exit burr control | $$$ |
| HDF backup board | Standard hit count | Good burr control | $$ |
| Phenolic backup board | Moderate hit count | Good for back-drill | $ |
| Lubricated aluminum entry | +20-40% stack height | Excellent micro-via quality | $$$ |
| Standard aluminum entry | Baseline | Good universal protection | $$ |
Stable feed rate and clean exits are what let you push hit count without micro-drill breakage. Pair the right board with the parameters from this tool — see our backup board range and aluminum entry boards.
| Material | RPM | Chip load | Feed (m/min) | Entry | Backup |
|---|---|---|---|---|---|
| FR4 (standard multilayer) | 90,000 | 0.012 | 2.16 | Aluminum entry sheet | HDF backup board |
| HDI / micro-via | 110,000 | 0.008 | 1.76 | Lubricant aluminum | UV melamine 880 backup board |
| Rogers (high-frequency) | 80,000 | 0.010 | 1.60 | Aluminum entry sheet | Phenolic backup board |
| PTFE / Teflon | 60,000 | 0.008 | 0.96 | Aluminum entry sheet | Phenolic backup board |
| IC substrate (ABF) | 120,000 | 0.006 | 1.44 | Lubricant aluminum | UV melamine 950 backup board |
| Ceramic PCB | 50,000 | 0.008 | 0.80 | Aluminum entry sheet | Phenolic backup board |
| Aluminum PCB (IMS) | 40,000 | 0.010 | 0.80 | Aluminum entry sheet | Phenolic backup board |
| Copper-core PCB | 30,000 | 0.010 | 0.60 | Aluminum entry sheet | Phenolic backup board |
Figures are qualified starting points cross-checked with published fabrication guidance and supplier benchmarks — validate on your own panels.
Hole density (HDI panel)
Representative field benchmarks for a 0.20 mm drill on standard FR4; actual results vary with stackup, machine and consumables — validate on your own panels.
Hole density is what turns a panel count into a heat and wear forecast: two panels with the same board area can differ by an order of magnitude in hits per panel, and the denser one consumes drill life, entry film and backup surface proportionally. Density also feeds back into the drilling program — dense zones concentrate exit-support wear on the backup board, so those zones are rotated or the sheet replaced sooner than the panel average suggests.
What is hole density? Holes per unit panel area (CPP) - how hole-rich a panel is.
What is a high-density panel? Many holes per area, typical of HDI and fine-pitch builds.
What is a micro-via? A tiny via (often <0.15 mm) for HDI; usually laser-formed.
What is laser drilling? UV/CO2 laser ablation of micro-vias, beating mechanical aspect-ratio limits.
What is hit count? Holes per bit; dense panels demand more of it.
What is cycle time? Seconds per panel; density drives drilling time.
What is mechanical drilling? Drilling with a coated bit for standard through-holes.
What is HDI? High-density interconnect with fine lines and micro-vias.
What is panel utilization? Share of panel area carrying holes.
What entry board for dense panels? A lubricant aluminum sheet for micro-hole cooling and centring.
What backup board for dense panels? UV melamine 880 for HDI/clean exits; HDF for cost FR4.
What is the difference between CPP and aspect ratio? CPP is area density; aspect ratio is depth vs hole size.
Cycle time per hole is the sum of feed time (stack height / feed rate), retract time, and table positioning. Throughput (holes/hour) is the inverse of cycle time multiplied by spindle count. A move from 2-up to 3-up stacking can increase throughput by 50% — if the entry board supports it.
Excellon — PCB drilling machines ↗
Panel drilling cost = (drill bit cost + entry board cost + backup board cost + machine time cost + overhead) ÷ good panels out. Scrap from drilling defects often dominates the cost equation. Reducing breakage and burr defects through better consumable selection frequently pays for itself within weeks.
IPC — PCB cost factors (IPC-2221) ↗
First-pass yield in drilling is driven by positional accuracy, hole wall quality, and burr height. Defect rate calculators on this site help model the impact of parameter shifts. A 1% improvement in yield on high-layer-count boards can save thousands of dollars per month.
Sierra Circuits — Back-drilling ↗
Spindle utilization (actual drilling time ÷ total shift time) is the key machine efficiency metric. Unplanned downtime for drill breakage (15–45 min per event) is the largest utilization killer. Consistent consumable quality reduces breakage frequency and improves OEE.
Posalux — PCB drilling solutions ↗
Back-drilling requires controlled-depth accuracy ±0.05 mm to remove the stub without damaging the target layer. The entry board choice matters: a dedicated back-drill entry sheet with coating provides consistent Z-reference for depth registration and protects the surface from the larger back-drill bit.
YUESHAN — Back-drill depth control guide
Drill resharpening can recover 60–80% of original tool life at 30–50% of new bit cost. The decision to resharpen depends on the number of regrinds possible (typically 3–5 for micro-drills) and the quality requirement of the target holes. Resharpening is most economical for standard-diameter drills above 0.3 mm.
Process and CAM engineers use these numbers across demanding builds:
Density alone rarely decides yield; how the drill behaves at that density is covered in the PCB drilling process: speed, accuracy & defect control.
The right entry and backup board is what actually lets you hold a stable feed rate without breakage. Explore the product lines:
HDF, UV melamine and phenolic backup boards for stable exits and burr control.
Product Page →Plain and coated aluminum entry boards, including lubricated grades for micro-holes.
PCB Aluminum Entry Board & Lubricant Entry Sheet →Self-lubricating entry sheets that cool and center the bit on HDI / micro-via drilling.
Lubricant-Coated Aluminum Entry Board →Coated back-drill entry sheets built for controlled-depth second-pass accuracy.
Back-Drill Aluminum HW600/HW900 →← Tools Hub Request TDS & Free Sample →