What Is a Lubricant Aluminum Entry Board?
In PCB mechanical drilling, an entry board is placed on top of the PCB stack before the drill enters the first panel. A lubricant aluminum entry board adds a functional lubricating layer to an aluminum entry sheet. The industry uses several overlapping names—LE Sheet, lubricated entry sheet, lubricant aluminum entry sheet, self-lubricating entry board and coated aluminum entry sheet—but two products should not be treated as equivalent until their coating chemistry, base thickness and drilling qualification are checked.
| Entity | Meaning | Why it matters |
|---|---|---|
| Aluminum base | Metal entry substrate that provides flatness, rigidity and thermal conduction | Controls entry geometry and part of total stack thickness |
| Lubricating layer | Functional polymer/lubricant coating on the entry side | Reduces friction and changes drill/chip behavior |
| LE Sheet | Established industry term for a lubricated aluminum entry sheet | Common supplier/specification language |
| Mechanical drilling | High-speed carbide drill process for through-holes / small holes | The primary process context for this material family |
Entity Dimension 1 — Materials & Construction
Aluminum sheet / foil
The aluminum layer supplies a flat entry plane, mechanical support and heat-spreading capacity. Commercial PCB entry products often use high-purity 1xxx-series aluminum; the exact alloy and temper must come from the supplier TDS.
Lubricant / polymer layer
The functional layer may be formulated as a water-soluble or other engineered coating. Its job is to reduce friction at drill entry and improve chip/tool interaction during the drilling cycle.
Two-layer entry material
The industry reference architecture is a lubricating layer over an aluminum sheet. Do not assume single-sided vs double-sided coating, exact coating thickness or chemistry without grade-specific documentation.
Entity Dimension 2 — Coating Chemistry & Physical Properties
| Property / entity | Engineering question | Buyer wording | How to validate |
|---|---|---|---|
| Coating chemistry | Does it melt/soften? Is it heat-stable? Is rinsing required? | water-soluble / hot-melt / thermoset / polymer coating | TDS + SDS + drilling test |
| Coating thickness | How much lubricant is available and how uniform is it? | lubricant layer thickness / coating weight | cross-section / thickness data / Cpk where available |
| Aluminum base thickness | How rigid is the entry layer and what does it add to total stack? | foil thickness / aluminum base | micrometer / TDS |
| Total thickness | Does the material fit the drill diameter and stack geometry? | 0.xx mm total thickness | incoming inspection |
| Flatness | Does the sheet maintain a repeatable top reference? | flatness / warpage | lot inspection |
| Water solubility / cleanability | Can residue be removed before wet processing? | water rinse / washable coating | supplier method + line trial |
| Thermal behavior | Does the coating reduce frictional heat or remain stable at higher temperature? | drill tip temperature / thermal stability | controlled drilling comparison |
Industry reference — not a YUESHAN specification
Mitsubishi Gas Chemical describes its LE SHEET as a lubricating layer on an aluminum sheet and publishes aluminum-sheet thicknesses in the approximately 70–150 µm class. Its public lineup covers different PCB thicknesses and drill diameters, including very small diameters. These figures are useful for understanding the product category, but they should not be copied into a YUESHAN purchase order unless YUESHAN's current TDS confirms the same value.
How Lubricant Entry Material Changes the Drilling Process
| Mechanism | What happens at the drill | Engineering output |
|---|---|---|
| Reduced friction | Lubricant forms a lower-friction interface around the rotating bit and chips | Lower tool wear / lower frictional heat |
| Lubricant transfer around the bit | For water-soluble / hot-melt systems, the lubricant can melt or soften and coat the bit during drilling | Smoother cutting and chip evacuation |
| Heat management | Reduced friction lowers heat generation; aluminum also spreads heat at the entry side | Lower smear risk / improved tool life |
| Entry stabilization | Flat aluminum base and lubricated interface reduce skid tendency | Improved hole-position accuracy |
| Debris evacuation | Lubrication helps chips move along the flute rather than dragging against the wall | Lower wall roughness / wicking / smear risk |
What a Lubricant Aluminum Entry Board Is — and Is Not
| Material | Same entity? | Main purpose | When to choose |
|---|---|---|---|
| Plain 1100 H18 aluminum entry board | No | Entry guidance, top-surface protection, heat spreading | Standard via drilling where plain aluminum is sufficient |
| Lubricant aluminum entry board / LE Sheet | Yes | Entry guidance + active lubrication/friction control | Small holes, HDI, higher stack or tool-life constraints |
| Back-drill aluminum sheet | No | Controlled-depth / Z-reference function for back drilling | Back-drill / via-stub control |
| Backup board | No | Bottom-side drill-exit support | Every drilling stack needs an exit-side support strategy |
| Phenolic / melamine backup material | No | Backup-side support, not entry lubrication | Selected by exit burr, hardness, moisture and stack needs |
Entity Dimension 3 — Applications & PCB Types
HDI PCB
As hole diameter falls and hole density rises, drill wear, skid, thermal load and hole-position variation become more sensitive to entry material.
HDI & IC substrate solution →Multilayer PCB
Lubricant entry material can be evaluated when stack height, tool life or wall quality becomes the throughput constraint.
Multilayer drilling guide →FPC / Rigid-Flex
Thin and flexible constructions may need tighter support and more careful material qualification; do not transfer a rigid-board recipe without testing.
BGA / IC substrate
Fine drilling and demanding hole quality raise the value of controlled lubrication, surface uniformity and consistent entry geometry.
RF / high-frequency PCB
Heat and smear control can matter more when laminate systems are sensitive to thermal/mechanical damage.
Back-drill support use
Lubricant-coated material may be useful for thermal/friction control, but controlled-depth back-drilling has a separate Z-reference requirement.
Back-drill selection guide →The Lubricant Entry Board in the PCB Drilling Process Chain
Hole diameter, PCB type, stack and failure mode
Total thickness, flatness, coating uniformity, surface defects
Entry board + PCB panels + qualified backup board
RPM, feed, chip load, drill geometry and hit count
Position, wall roughness, smear, wicking, breakage and cleanability
Machines, Tools & Process Parameters Connected to This Entity
| Entity | Why it is connected | Useful YUESHAN asset |
|---|---|---|
| High-speed PCB drill spindle | RPM and runout directly change cutting behavior | PCB Drill RPM Calculator |
| Tungsten-carbide / carbide micro drill | Diameter, flute geometry and wear determine how much lubrication matters | Tool Life Calculator |
| Feed rate | Changes chip load, heat and wall finish | Feed Rate Calculator |
| Chip load | Connects feed, RPM and flutes | Chip Load Calculator |
| Stack height | Changes tool engagement and productivity | Stack Height Calculator |
| Hole density | Higher density increases thermal and wear accumulation | Hole Density Calculator |
Entity Dimension 5 — Engineering Problems This Material Is Used to Solve
| Observed problem | Why lubricant entry material may help | Other variables that must be checked |
|---|---|---|
| Frequent micro-drill breakage | Lower friction and improved chip/tool interaction can reduce tool stress | RPM, feed, runout, drill wear, stack height, backup support |
| Hole-position deviation / drill skid | Lubricated, stable entry interface can improve entry behavior | Spindle runout, entry flatness, press-foot setup, drill geometry |
| Resin smear | Reduced frictional heat and smoother debris removal can reduce smear tendency | Laminate Tg, drill wear, feed, hit count, desmear process |
| Rough hole wall / wicking | Lubrication and chip evacuation can reduce damaging interaction with resin/glass | Drill geometry, laminate, parameters, wear |
| Short drill life | Lower wear at entry and during chip evacuation can extend usable hits | Bit quality, hole count, regrind policy, material stack |
| Cannot increase stacked panels | Better drilling stability can support higher stack in a qualified process | Flute length, machine capacity, positional tolerance, total stack |
Decision Matrix — Plain Aluminum vs Lubricant Entry vs Back-Drill Entry
| Decision factor | Plain aluminum entry | Lubricant aluminum / LE Sheet | Dedicated back-drill entry |
|---|---|---|---|
| Standard through-hole guidance | Strong fit | Strong fit | Possible but not the primary intent |
| Small-hole / HDI lubrication | Limited | Primary strength | Depends on coating system |
| Drill-wear reduction | Baseline | Designed for this | Secondary to depth-control function |
| Water-soluble cleanability | Not applicable | Available on classic LE Sheet systems | Grade-specific |
| Controlled-depth Z-reference | Not specialized | Not the primary role | Primary strength |
| Best buyer question | “Do I need more than plain aluminum?” | “How do I improve fine-hole drilling?” | “How do I hold back-drill depth/stub?” |
What Should Be on a Lubricant Aluminum Entry Board RFQ?
A useful RFQ should define the process and the material—not just say “LE sheet.”
Material / dimensional inputs
- Required sheet size
- Aluminum alloy / temper if specified
- Aluminum-base thickness
- Lubricant/coating type
- Total thickness and tolerance
- Flatness requirement
- Coating thickness / uniformity if controlled
Drilling / qualification inputs
- Smallest drill diameter
- PCB material and layer count
- Panels per stack
- RPM / feed / hit target
- Hole-position tolerance
- Wall roughness / smear / wicking criteria
- Current drill-life or breakage baseline
Send your current drilling window—not just a product name
YUESHAN can recommend a commercial lubricant aluminum grade faster when the request includes drill diameter, PCB material, stack height, RPM/feed, current entry sheet and the failure you want to improve.
How to Qualify a Lubricant Aluminum Entry Board
- Choose a representative production panel. Prefer a stable, high-volume board where the current breakage / smear / position baseline is known.
- Hold the process constant. Same machine, drill lot, backup board, program, feed, RPM and stack.
- Compare plain aluminum vs candidate lubricant entry. Do not change multiple variables at once.
- Measure outputs that matter. Hole-position accuracy, wall roughness, smear, wicking, drill wear, breakage, maximum qualified stack and cleanability.
- Calculate cost per good hole. Material price matters only after yield, drill life and throughput are included.
Evidence Layer — What Can Be Cited, and What Must Stay Grade-Specific?
MGC LE SHEET
MGC publicly describes LE SHEET as a lubricating layer plus aluminum sheet and states benefits in drill wear, through-hole quality, hole-position accuracy, stack height and drill life.
Industry category evidence, not YUESHAN product certification.
Water-soluble polymer / aluminum structures
Patent literature documents water-soluble polymer layers over aluminum foil for PCB drilling and describes reductions in frictional heat, drill wear and positional problems.
Useful mechanism evidence; not a substitute for current commercial TDS.
Production comparisons
YUESHAN publishes line-specific comparisons for thermoset-coated entry material, drill breakage, temperature and stack behavior. Each result should be read with its process conditions.
View YUESHAN drilling data →Technical References & Source Hierarchy
A-level / primary product-category sources
- Mitsubishi Gas Chemical — LE SHEET product overview
- Mitsubishi Gas Chemical — Effects of LE SHEET
- Mitsubishi Gas Chemical — LE SHEET lineup by hole diameter
B-level / patent & technical mechanism sources
- EP2124513A2 — lubricant sheet with water-soluble polymer layer + aluminum foil for PCB drilling
- US6890664B2 — entry boards for drilling small holes; lubricant layer on aluminum base
- Related patent literature on lubricated PCB drilling sheets
YUESHAN source layer
Related Entity Cluster
Lubricant Aluminum Entry Board FAQ
What is the difference between an LE Sheet and plain aluminum entry board?
Plain aluminum provides entry guidance and heat spreading. An LE Sheet adds a lubricating layer designed to reduce friction, tool wear and drilling-quality problems, especially as hole diameter decreases.
Is every lubricant aluminum entry board water-soluble?
No. Mitsubishi Gas Chemical's classic LE Sheet uses a water-soluble lubricant system, while the broader market includes other engineered coating systems, including heat-stable coatings. Always specify the coating chemistry rather than relying on the generic product name.
What PCB applications benefit most?
The material is most relevant when small hole diameter, high hole density, high stack height, drill wear, hole-position accuracy, roughness or smear are limiting production. HDI, BGA, IC-substrate and demanding multilayer drilling are common evaluation cases.
Does a lubricant entry board automatically eliminate drill breakage?
No. It can reduce one source of friction and tool stress, but drill quality also depends on spindle runout, RPM, feed/chip load, drill geometry, wear, PCB material, stack height and backup support.
What should be measured in a qualification test?
At minimum: hole-position accuracy, wall roughness, smear, wicking or interface damage, drill wear/hit count, breakage frequency, maximum qualified stack height and cleanability before downstream processing.
Next Step: Match the Entry Material to Your Drilling Problem
If you are comparing plain aluminum, water-soluble LE Sheet and thermally stable coated aluminum, send the smallest drill diameter, PCB type/layer count, current stack and your main failure mode. YUESHAN can prepare a grade recommendation, TDS/SDS and sample plan for a controlled side-by-side test.