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LCP

Polímero de Cristal Líquido

LCP·High Performance·Semi-crystalline

LCP (Liquid Crystal Polymer) is the strangest and most expensive plastic in the mass injection market, and at the same time the only one that lets you mold fine-pitch SMT connectors that survive 260°C reflow without deforming. Its unique feature: molecules are rigid aromatic rods that in the molten state form a nematic liquid-crystal phase —they align in parallel like logs in a river. When you inject, that orientation "freezes" into the part, generating extreme anisotropy: CTE of 5-10 ppm/K in flow direction (similar to aluminum!), 50-80 ppm/K perpendicular.

The two major families: Vectra (Celanese, naphthalene-based, melt 285-335°C) and Xydar (Solvay, biphenol-based, melt 370-450°C — for extremes). Japan leads with Sumikasuper (Sumitomo) and Laperos (Polyplastics). DuPont had Zenite. The dominant application is SMT connectors —fine-pitch board-to-board, DDR, USB-C, HDMI— where lead-free reflow tolerance and <0.3 mm wall moldability are critical.

Other virtues: moisture absorption <0.05% (the lowest of any thermoplastic), HDT 200-280°C+, inherent V-0 without halogens, UV stability 90%+ after 2000h. Flipside: high cost ($15-30/kg), weak weld lines because orientation doesn't recover entanglement. Are you running LCP in electronics? Share your experience with thin walls and warpage in the comments.

The ranges shown in these data tables were compiled by the MVPS team from various parameter sheets and literature, integrating the lower and upper limits for each material type.

This information must be carefully reviewed when developing injection molding processes. Final ranges and processing tolerances are the responsibility of the engineer in charge.

These ranges are not recommended for developing specific process tolerances. MVPS always recommends requesting and consulting the supplier's data sheet.

General Properties

Chemical StructureSemi-crystalline
Specific Gravity (Density)1.76:1
L/D Ratio18 – 24
Compression Ratio2 – 3
Tonnage Factor6.18 – 9.27kN/cm²
Thermal Diffusivity0.307mm²/s
Max Shear Rate60,0001/s
Shrinkage0.1 – 0.6%
Regrind⚠ Caution
Heat Deflection (HDT) @ 1.82 MPa183°C
Glass Transition (Tg) @ 10°C/min120°C
Vicat Softening @ 50N144°C

Drying

Drying Temperature149 – 179°C
Drying Time2 – 8h
Recommended Moisture0.03%
Recommended Dryer TypeDesiccant
Dew Point-28.9°C

Temperatures

Melt279 – 343°C
Nozzle288 – 354°C
Front277 – 346°C
Middle271 – 343°C
Rear268 – 349°C
Demolding102 – 132°C
Mold (Cooling)85 – 121°C
Feed Throat35 – 79°C

Processing

Back Pressure1.4 – 6.9bar
Screw Speed40 – 70RPM
Injection SpeedHigh
Barrel Occupancy25 – 75%
Injection Pressure800 – 1,300Pbar
Holding Pressure200 – 1,040Pbar
Cushion6.4 – 12.7mm

Mold

Runner Diameter2.03 – 4.06mm
Gate Diameter0.51 – 1.02mm
Gate Area0.2 – 0.81mm²
Wall Thickness0.3 – 1.52mm

Venting

Depth (Vent Depth)0.0102 – 0.0305mm
Land (Vent Land)0.762 – 1.52mm
Width (Vent / Clearance)4.06 – 12.7mm
Relief (Relief Channel)0.2032 – 0.4064mm

Frequently asked questions

An **LCP** is a thermoplastic whose molecules are **rigid mesogens** —typically chains of aromatic rings linked by ester bonds (p-hydroxybenzoate, hydroxynaphthoate, biphenol). In the molten state, those rigid rods don't coil randomly like a conventional polymer: **they align in parallel** forming a **nematic liquid-crystal state**. When you inject, flow orients those rods, and upon solidification they remain frozen in orientation —generating parts with extreme anisotropic properties.
- **Vectra** (Celanese, originally Hoechst Celanese 1985): **naphthalene-based** copolymer (p-hydroxybenzoate + hydroxynaphthoate). Melt 285-335°C. HDT 180-240°C. Easier to process, **SMT market standard**. - **Xydar** (Solvay, originally Amoco): **biphenol-based** (terephthalic + dihydroxybiphenyl + p-hydroxybenzoate). Melt **370-450°C**. HDT up to **350°C**. The "high-end" of high-end — used where temperature is extreme (microwave, cookware). - **Sumikasuper** (Sumitomo) and **Laperos** (Polyplastics) are the Japanese equivalents of Vectra.
Five unique technical reasons: - **(1) Lead-free reflow tolerance** (260-265°C peak): standard-grade HDT >250°C withstands without deforming. - **(2) Ultra-thin wall moldability**: oriented flow keeps viscosity very low under high shear —pins can be molded at 0.3 mm pitch with 0.15 mm walls. - **(3) Exceptional dimensional stability**: the part doesn't move between molding and SMT due to extremely low moisture absorption. - **(4) Inherent V-0 flammability** without bromated additives (RoHS clean). - **(5) Dielectric insulator** stable up to GHz.
Chains oriented in flow direction (MD) give the part **dramatically different properties depending on direction**: - **MD (flow direction)**: high modulus, almost metallic thermal expansion (5-10 ppm/K), excellent tensile strength. - **TD (transverse direction)**: much lower modulus and strength, **thermal expansion 5-10× higher** (50-80 ppm/K). **Design consequence**: you must think about **gate layout** and **flow pattern** because they define orientation in each zone of the part. A part with radial flow from the center behaves differently than one with linear flow.
**The big weakness of LCP**. When two flow fronts meet, oriented chains **don't re-entangle** —the rigid rods coming from each side just collide in different orientations without fusing. Result: **weld line strength can drop to 20-40%** of base material. **Mitigations**: minimize number of gates (prefer single central gate), avoid thin cores that generate divergent-convergent flow, increase mold temperature to 130-140°C to improve local mixing. In connectors, designs are deliberately laid out so weld lines fall in non-critical areas.
For Vectra (standard): - **Drying**: 150°C × 4-6 h in desiccant dryer (critical). - **Melt**: 285-335°C (natural grades) up to 350°C (reinforced). - **Mold**: 90-140°C (hot — improves flow and reduces surface orientation stress). - **Residence**: max 4-5 min. - **Injection speed**: fast —LCP benefits from extreme shear thinning. For Xydar: - **Drying**: 150-170°C × 4-6 h. - **Melt**: 370-450°C —requires special high-temperature screw and barrel. - **Mold**: 180-260°C.
- **LCP**: **#1 for fine-pitch SMT** and high-frequency connectors (USB, DDR). Ultra-thin walls. Medium-high cost. Anisotropic. - **PPS** ([Polyphenylene Sulfide](/en/desktop/datos-de-resina/pps)): second option for more robust SMT, better weld lines, less anisotropy. Similar HDT (~260°C). Medium cost. - **PEEK** ([Polyether Ether Ketone](/en/desktop/datos-de-resina/peek)): aerospace, implantable medical, maximum temperature (HDT 320°C continuous). Very high cost ($50-100/kg). Not for volume SMT. **2026 rule**: SMT volume → LCP. Robust SMT with weld lines → PPS. Implants/aerospace → PEEK.
**Anisotropic and very low in MD**: - **MD (flow direction)**: 0.0-0.3% (practically zero!) —chain orientation resists contraction. - **TD (transverse)**: 0.4-0.8%. - **Thickness (Z)**: 0.4-1.0%. Low MD shrinkage is what allows **micron-order dimensional tolerances** in connectors —tolerances that only other LCPs or fiber-reinforced materials can achieve.
**Mechanically yes**, **but with limitations**. Vectra and Xydar maintain acceptable properties after 1-3 recyclings, but **crystalline orientation gradually degrades** —chains break with each screw pass, lowering molecular weight. For critical applications like SMT connectors, **regrind is not used**. For less critical applications (cookware, automotive internal parts), 10-25% regrind is accepted without issues. The **high virgin cost** justifies closed-loop programs at many electronics OEMs.
**$15-30/kg for Vectra**, **$30-60/kg for Xydar**, vs $2-5 for an engineering plastic commodity like PA66 or ABS. Reasons: - **Expensive monomers**: p-hydroxybenzoate, hydroxynaphthoate, and biphenol are low-scale chemical intermediates vs ethylene or propylene. - **Complex polymerization**: high-temperature condensation with byproduct extraction. - **Low-volume production**: ~50-100 thousand tons/year globally (vs 50+ million for PE), minimal economy of scale. - **Captive high-end market**: inelastic electronics demand allows high prices. The good news: for the thickness you need (0.3-0.5 mm in connectors), an LCP part weighs **grams**, not kilograms —the per-part cost stays reasonable.

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