LE Sheet & Lubricant-Coated Aluminum for PCB Drilling — Material Profile

Material Profile — Not a Product Listing

This page explains the LE Sheet / lubricant-coated aluminum material system: construction, coating chemistry, water solubility, heat/friction behavior and drilling-quality entities. For YUESHAN commercial grades, samples, TDS/SDS and quotations, use the Lubricant Aluminum product page.

What Is an LE Sheet?

Mitsubishi Gas Chemical (MGC), a primary industry source for the term, defines LE SHEET as an entry sheet for mechanical drilling consisting of a lubricating layer and an aluminum sheet. The material is used above printed wiring boards during drilling.

Across search results, the same material family appears under several related phrases: LE Sheet, lubricated entry sheet, lubricant aluminum entry sheet, lubricating aluminum entry board, coated aluminum entry sheet, lube sheet and PCB drilling entry sheet. These are useful semantic variants, but coating chemistry and construction must still be checked before treating two grades as equivalent.

LE Sheet Construction: Lubricating Layer + Aluminum Base

The basic material architecture is simple:

1. Aluminum base: provides a flat, dimensionally stable entry layer and conducts heat away from the initial drill contact.
2. Lubricating layer: reduces friction between the drill, chips and entry interface. Depending on chemistry, it may be water-soluble / hot-melt or a heat-stable coated film.

MGC publishes aluminum-sheet thicknesses in roughly the 70–150 μm class for its LE Sheet system. Chinese industry pages commonly publish total thickness, aluminum-base thickness and lubricant-layer thickness separately — for example 0.13 mm total with a 0.10 mm aluminum base plus 0.03 mm lubricant layer. These are useful benchmark categories, not YUESHAN specifications unless confirmed by the current TDS.

How the Lubricating Layer Works During Drilling

For water-soluble hot-melt systems, drilling heat softens or melts the lubricant at the contact zone. The lubricant can coat the drill and reduce friction while helping chips move up the flute. MGC states that this lowers frictional heat generation, reduces wear and helps debris discharge smoothly.

The material mechanism connects directly to the entities engineers search for:

• drill-bit wear / drill life;
• hole-position accuracy;
• hole-wall roughness;
• resin smear;
• wicking / plating soak-in;
• micro-cracks between glass fiber and resin;
• chip evacuation;
• stack height / number of overlaid boards;
• drilling cost per good hole.

Water-Soluble vs Thermoset Coating Systems

Coating system	Material behavior	Engineering questions
Water-soluble / hot-melt lubricant	Softens or melts under drilling heat and can be removed with water rinse	Solubility, rinse conditions, humidity sensitivity, coating thickness, residue
Thermoset / heat-stable coating	Designed to remain dimensionally stable at higher temperature while providing a low-friction interface	Thermal stability, film uniformity, adhesion, drilling residue, compatibility with downstream cleaning

Do not assume “LE Sheet” automatically means one chemistry. MGC's well-known LE Sheet is water-soluble; other suppliers market thermoset or alternative coated entry systems. Qualification should therefore specify both base aluminum and coating chemistry.

Hole Quality Entities: Smear, Wicking and Wall Roughness

MGC's published technical pages are especially useful because they describe the output variables rather than only the material. Their reported benefits include less hole-wall roughness, less wicking, less resin smear, improved hole-position accuracy, increased stack height and longer drill-bit life.

These terms should also guide internal process qualification. Instead of asking only “Did the coated sheet reduce temperature?”, track:

• position error / CpK;
• wall roughness after drilling;
• smear incidence after sectioning;
• wicking or resin/glass interface damage;
• drill wear after a defined hit count;
• breakage frequency;
• maximum qualified stack height;
• cleanability before subsequent plating.

Engineering Variables to Specify

Variable	Why it matters	Common search / procurement wording
Aluminum alloy / base	Controls base-sheet mechanical and thermal behavior	1100 aluminum, 1060 aluminum, aluminum foil base
Base thickness	Affects entry rigidity and total material thickness	70–150 μm, 0.10 mm, 0.12 mm, 0.15 mm
Lubricant-layer thickness	Influences friction, heat transfer and coating consumption	lubricating layer, coating thickness, resin layer
Total thickness	Must fit drill diameter and stack geometry	0.13 mm, 0.16 mm, 0.18 mm, 0.20 mm
Coating chemistry	Determines melting / thermal behavior and cleaning route	water-soluble, hot-melt, thermoset, polymer coating
Flatness / thickness tolerance	Supports repeatable Z geometry and drill entry	flatness, dimensional accuracy, thickness tolerance
Water solubility / cleanability	Relevant before PTH or downstream wet processing	water rinse, residue, washable coating
Hole-quality output	Validates the material under real drilling conditions	roughness, smear, wicking, CpK, drill life, stack height

When to Evaluate Lubricant-Coated Entry Material

A lubricant-coated entry sheet becomes especially relevant as drill diameter decreases, hole density rises, stack height increases or the laminate becomes more sensitive to heat and smear. MGC's product lineup explicitly differentiates grades by PCB thickness and drill diameter, including very small-diameter drilling.

For YUESHAN commercial selection, use the Lubricant Aluminum product page. For application diagnosis, see the signs you need a lubricated entry sheet and lubricant coating thickness calculator.

External Technical References

• Mitsubishi Gas Chemical — LE SHEET overview
• MGC — LE SHEET effects: roughness, smear, wicking, position accuracy and drill life
• MGC — LE SHEET lineup by hole diameter
• IPC design standards

External references are cited for material terminology and drilling-mechanism context only; they do not imply endorsement of YUESHAN.

LE Sheet Material FAQ