A coated aluminum entry board is a thin aluminium sheet with a resin lubricant film applied to the drill-entry surface. The film cools and lubricates the bit during microvia drilling, reducing drill wear and improving hole-position accuracy below what plain aluminum can achieve.
A coated aluminum entry board is a thin aluminium sheet with a resin lubricant film on the drill-entry surface. The film cools and lubricates the bit during microvia drilling, reducing wear and improving hole-position accuracy versus plain 1100 H18 foil, which relies only on the metal's natural softening to centre the bit.
A coated aluminum entry board (also called lubricant aluminum, thermoset-coated entry, or coated entry sheet) is an aluminum entry board with a resin-based lubricant film on the surface that contacts the drill bit. The film serves two purposes: it cools the drill tip by absorbing friction heat, and it lubricates the drill flutes to reduce wear and prevent resin smear on hole walls.
Where plain 1100 H18 aluminum entry boards rely on the metal's natural softening behaviour to centre the bit, coated boards add an engineered film layer that provides additional thermal and mechanical margin for the most demanding applications: HDI microvia, BGA and IC substrate drilling.
The sheet underneath the film is a standard aluminium entry board — its alloy, temper and thickness set the mechanical baseline the coating builds on.
As hole diameters shrink below Ø0.15 mm, the margin for error narrows. A plain aluminum entry board works well for standard drilling, but at microvia scale the friction heat becomes concentrated enough to affect bit life and hole quality. The coated film addresses this by:
Two main coating chemistries are available, selected based on hole size, climate and cost target — and the commercial half of the choice (quote structure, MOQ, spec lines) is in the coated entry board buying guide:
A heat-stable resin film that does not soften at drilling temperature. This prevents hole-wall melt rings and provides the most consistent lubrication. The preferred choice for HDI microvia below Ø0.15 mm, BGA and IC substrate, and humid plants where water-soluble films would degrade.
Full thermoset coated specifications →
A soluble resin film that costs less than thermoset but is sensitive to humidity. Suitable for general HDI drilling above Ø0.10 mm in climate-controlled factories. The film rinses off in post-drill cleaning.
Base thickness affects drill-depth reference and coating uniformity as much as coating chemistry does, and the aluminium entry board thickness guide explains how to choose it.
The coated aluminum entry board is the top sheet in the consumable stack for HDI and microvia production. It pairs with:
The full product range is covered under Lubricant & Coated Aluminum overview, which includes the subtype comparison table and coating option details.
If the choice still depends on your exact hole sizes and stack, the entry board selector narrows plain, coated and back-drill options from a few inputs.
| Factor | Plain 1100 H18 | Coated Aluminum |
|---|---|---|
| Smallest hole | ≥Ø0.20 mm | ≥Ø0.075 mm (with thermoset) |
| Bit life gain | Baseline | +30–50% vs plain |
| Hole position CpK | ≥1.33 | ≥1.67 achievable |
| Best for | Standard multilayer | HDI / BGA / IC / microvia |
| Cost per sheet | $ | $$ |
For a detailed comparison of all entry board types, see the aluminum entry board selection guide.
The plain side of this comparison is AA1100 H18 aluminium — see the 1100 H18 alloy, temper and thickness specifications for what each number means and how to check a supplier's sheet.
Coating is only one of the variables in play, so weigh hole size, stack and plant conditions against the seven factors for choosing an aluminium entry board.
A coated aluminum entry board has a resin lubricant film that cools and lubricates the drill bit. Used for HDI, BGA and IC substrate microvia drilling where plain aluminum cannot deliver the required precision.
For microvia below Ø0.15 mm and humid plants, use thermoset (220°C). Water-soluble fits general HDI above Ø0.10 mm where cost leads and humidity is controlled.
Yes. YUESHAN thermoset coated aluminum is engineered as an leading coated-aluminum alternative. See the How We Compare to L.C.O for details.
UV Melamine 880 or 950 for HDI microvia, or Phenolic PHE for IC substrate. The backup board controls exit burr while the coated entry controls location accuracy.
If the choice still depends on your specific hole sizes and stack, the entry board selector narrows coated, plain and back-drill options in a few inputs.
Need to qualify a coated aluminum entry board for a new HDI program? Send your smallest hole size, stack-up and current entry board spec — our engineers will recommend the right coating type and base thickness within one business day and ship samples within 5–7 days. Reach Mr. Lucky Xu on WhatsApp or email.