Why Korean PCB Makers Choose Lubricated Aluminum Entry Sheets

South Korea is home to some of the most advanced PCB manufacturers on the planet, producing HDI substrates, IC packages, and telecom backplanes for smartphones, AI servers, 5G base stations and automotive electronics — boards where via diameters routinely fall below 0.15 mm and layer counts climb past 20.

At that level of precision, the aluminum entry sheet stops being a commodity. It becomes a process-critical component. And increasingly, Korean engineers specify lubricated aluminum entry sheets — coated aluminum entry boards with a functional resin layer — over plain 1100 H18 aluminum.

The Eight Pain Points

For high-end PCB makers, eight challenges drive the shift toward coated entry sheets:

1. Hole position accuracy — at sub-0.15 mm vias, a wobbling bit destroys the board. A soft resin coating centers the bit on entry.
2. Drill bit breakage — micro-vias are brutal on bits; lubrication cuts friction heat and extends bit life.
3. Burr reduction — exit burrs mean deburring cost and damage risk.
4. Nail heading / wicking — inner-layer copper deformation at material interfaces, worsened by vibration.
5. Water-soluble, easy-clean coating — Korean fabs run tight cleanliness standards; a coating that washes off with water and leaves no residue is a real advantage.
6. Higher stack height — more panels per hit means more throughput per shift.
7. Small-hole capability (<0.15 mm) — HDI and IC substrates live here.
8. Compatibility with High-Tg / halogen-free / thick copper — the materials Korean fabs specialize in.

A plain aluminum entry board addresses almost none of these. A lubricated aluminum entry board addresses most of them at once.

What a Lubricated Coated Aluminum Entry Sheet Does

The resin coating on a coated aluminum sheet performs three jobs during drilling:

• Centering: the soft resin film guides the bit precisely into position, improving hole position accuracy on micro-vias.
• Cooling: the coating absorbs friction heat as it melts, dropping bit temperature by up to 30% (cooling index 8-9/10).
• Lubrication: a continuous lubricating film cleans and coats the bit, reducing wear and preventing drill bit breakage.

Two Resin Types Matter

• thermoset-coated (thermoset): heat-resistant to 220°C, storage-friendly, best for HDI micro-vias, BGA and IC substrates below Ø0.10 mm. Our recommended default for fine-feature drilling.
• Water-soluble type: fully dissolves in water for easy cleaning with no residue — ideal for fabs with strict cleanliness requirements, and supports moderate increase in stack height.

For BGA and IC substrates (vias <Ø0.10 mm), use thermoset-coated only. Water-soluble coatings can soften at drilling temperatures and create "hole melt rings."

Why This Matters for Advanced PCB Manufacturers

For makers of HDI, IC substrate and high-layer-count boards, the value proposition of a qualified coated aluminum supply is straightforward:

• Same spec, better cost structure. 1100 H18 base, ±0.005 mm thickness tolerance, thermoset or water-soluble coating — matching the performance advanced fabs expect, at a competitive landed cost.
• Fast sampling. Sample kits ship within 5-7 working days; side-by-side comparison against a current supplier is standard.
• Full stack compatibility. Coated aluminum entry + UV Melamine backup + back-drill sheet from one source.

What to Verify Before You Qualify a Supplier

• Aluminum grade and temper: 1100 H18, thickness tolerance ≤±0.005 mm
• Coating type matches your application (thermoset L.C.O for <Ø0.10 mm; water-soluble for general HDI)
• Cooling index ≥8/10, lubrication index ≥8/10
• Water-soluble option leaves no residue after cleaning
• Flatness of backup board ≤0.10 mm (the entry sheet cannot fix a bad backup)
• TDS / MSDS available; SGS / RoHS documentation on request

For more detail, see our HDI & IC Substrate solution page and the backup board selection guide.