LCP plastic

LCP plastic is a thermoplastic high-performance material for particularly precise, thin-walled and thermally stressed components. Liquid Crystal Polymers combine high heat deflection temperature with very low moisture absorption, good chemical resistance and excellent electrical properties.

Typical areas of application are connectors, bobbins, sensor components, chip carriers and other miniature components for the electronics and semiconductor industries. Which LCP type is suitable, however, depends strongly on the temperature load, the mechanical stress, the required approvals and the intended processing.

What is LCP plastic?

The abbreviation LCP stands for Liquid Crystal Polymer. This is not a single plastic, but a group of aromatic, thermoplastic high-performance polymers.

The polymer chains align strongly in the direction of flow during processing. This ordered molecular structure gives LCP high strength and stiffness, but at the same time leads to direction-dependent, so-called anisotropic material properties. Component design, the position of weld lines and the orientation of the fibres must therefore be taken into account already at the design stage.

LCP is one of the engineering plastics for demanding applications. An overarching comparison of suitable materials is provided by the guide to material selection for high-performance plastics.

Properties of LCP plastic

High temperature resistance

Depending on the polymer structure, reinforcement and material type, LCP exhibits a high heat deflection temperature. For short periods, many types can withstand the high temperatures of modern soldering processes. The material is therefore frequently used for electronic components that are processed in reflow or wave soldering.

However, the actually permissible continuous service temperature must not be stated across the board as 300 °C. It must be taken from the technical data sheet of the specific LCP type and additionally depends on the duration of load, component geometry and ambient conditions.

High strength and stiffness

In particular glass-fibre or mineral-reinforced LCP compounds achieve high stiffness and mechanical strength. The material is therefore suitable for very small, delicate components in which thin wall thicknesses must be combined with high dimensional accuracy.

Due to the strong molecular orientation, strength, shrinkage and thermal expansion differ in and transverse to the direction of flow. LCP components must therefore be designed in a manner appropriate to the material and processing.

Very good dimensional stability

The low water absorption and the low thermal expansion of many LCP compounds support high dimensional accuracy. Compared with hygroscopic plastics such as polyamide, moisture causes only slight dimensional changes.

This is particularly important for plug contacts, micro components and precise electrical components whose function depends on tight tolerances.

Low water absorption

LCP absorbs very little moisture. As a result, electrical and mechanical properties remain largely stable even under changing humidity. The exact value depends on the respective type and the test method used.

This property also facilitates processing. Nevertheless, the drying specifications of the material manufacturer must be observed, as residual moisture can impair surface quality and process reliability.

Good chemical resistance

LCP is resistant to numerous fuels, oils, greases, alcohols, acids and other industrial media. However, the resistance depends on the specific chemical, its concentration, the temperature and the duration of exposure.

Before use in aggressive media, an application-specific resistance test is therefore always required. For applications with particularly high chemical exposure, PTFE, PEEK or PPS may also be suitable alternatives depending on the mechanical requirements.

Electrical insulating properties

LCP offers good electrical insulating properties, a high dielectric strength and, with suitable types, favourable dielectric properties for high-frequency applications. The low moisture absorption helps to keep these values comparatively stable under changing ambient conditions.

The material is therefore frequently used for connectors, bobbins, relay components, sensor housings and other components of the electronics industry and electrical industry.

Flame retardancy

Many commercial LCP types are formulated to be flame retardant and achieve demanding classifications according to UL 94 at low wall thicknesses. However, a specific fire protection class may only be stated for the specifically tested material type and component thickness.

Low melt viscosity

In the melt, LCP has very good flowability. This allows long flow paths, fine structures and very thin wall thicknesses to be realised. This property is a key reason for its use in miniaturised electronic components.

LCP properties at a glance

Property	Significance for the application
High heat deflection temperature	Suitable for thermally stressed components and high-temperature soldering processes
High stiffness	Dimensionally stable components even at low wall thicknesses
Very low water absorption	Low moisture-related changes in dimensions and properties
Good chemical resistance	Use in contact with many industrial media possible
Good electrical insulation	Suitable for connectors, bobbins and sensor components
Very good flowability	Production of delicate and thin-walled injection-moulded parts
Low shrinkage	High dimensional accuracy with suitable mould and process design
Anisotropic material behaviour	Direction of flow and fibre orientation must be taken into account in the design

LCP types and material modifications

LCP is predominantly used as a modified compound. Fillers and reinforcing materials specifically change the mechanical, thermal and electrical properties.

• Unreinforced LCP: for applications with high requirements for flowability, surface quality or electrical properties
• Glass-fibre reinforced LCP: for higher strength, stiffness and heat deflection temperature
• Mineral-filled LCP: for reduced shrinkage, dimensional accuracy and controlled warpage behaviour
• Glass-fibre and mineral-filled LCP: as a balanced material for precise technical components
• Conductively modified LCP: for components with requirements for electrical conductivity or electrostatic dissipation
• Flame-retardant LCP: for electrical and electronic applications with defined fire protection requirements

The selection must not be made on the basis of the polymer designation alone. What is decisive is the specific data sheet, the approvals and the properties tested for the component. Further information on specifically adapted materials can be found under modified plastics.

LCP plastic data sheet and technical characteristics

The technical characteristics of LCP differ considerably depending on the polymer structure, glass-fibre or mineral filling and the specific material type. Values for temperature resistance, tensile strength, modulus of elasticity, density, shrinkage and electrical properties should therefore always be taken from the data sheet of the respective LCP compound.

Processing of LCP

LCP in injection moulding

Injection moulding is the most important processing method for LCP. The low melt viscosity enables complex cavities and very thin wall areas to be filled. The material is therefore particularly suitable for miniature components and highly integrated functional components.

Nevertheless, processing places high demands on the mould and process control. The following must be taken into account in particular:

• sufficiently high and stable melt temperature
• suitable mould temperature control
• correct drying in accordance with the material data sheet
• high injection speed with controlled process
• material-appropriate gate and flow path design
• minimisation of critical weld lines
• consideration of direction-dependent shrinkage

Due to the pronounced orientation, mechanical weak points can arise if weld lines or load directions are arranged unfavourably. Early coordination between design, mould making and material selection is therefore particularly important.

Extrusion of LCP

Depending on the material type, LCP can also be extruded into films, fibres or thin profiles. Extruded LCP films are used, for example, in flexible electrical circuits and high-frequency applications.

Information on the manufacturing options available at Martan Plastics can be found in the section extruding plastic. Whether a specific LCP type and geometry can be extruded must be checked on a project-specific basis.

Machining of LCP

In principle, LCP can be milled, drilled or turned. In practice, however, the material is predominantly processed directly by injection moulding, as LCP semi-finished products are less widespread than semi-finished products made of PEEK, PTFE or other engineering plastics.

With filled and reinforced types, abrasive constituents can lead to increased tool wear. Sharp tools, stable clamping and adapted cutting parameters help to avoid chipping and damage to delicate contours.

For individually manufactured components, Martan Plastics offers various methods of plastic machining as well as precise CNC turning of plastic parts. The technical feasibility depends on the material type, semi-finished product availability, geometry and quantity.

Bonding, welding and coating

Bonding LCP can be demanding due to the low surface energy and the chemically resistant surface. Pretreatments such as plasma, corona or chemical activation can improve adhesion. The adhesive and pretreatment must be matched to the specific LCP type and the operating conditions.

Depending on the component geometry and type, thermal joining methods, ultrasonic welding or laser welding are possible. Metallising and coating of LCP are also used in electronic applications, but require suitable surface pretreatments and matched processes.

Areas of application of LCP plastic

Electronics and electrical engineering

The electronics industry is one of the most important areas of application for LCP. The material combines electrical insulation, dimensional accuracy, flame retardancy and soldering heat resistance with very good processability at thin wall thicknesses.

Typical components are:

• connectors and connector housings
• bobbins
• relay bases and switch components
• chip carriers and component sockets
• sensor housings
• antenna components
• high-frequency components
• components for flexible circuits

Semiconductor industry

In the semiconductor industry, LCP is used for precise carrier, insulation and connection components. The low moisture absorption and high dimensional accuracy are particularly advantageous with small component dimensions and tight electrical clearances.

Depending on the application, purity, outgassing behaviour, electrostatic properties and particle formation must also be checked.

Vehicle construction

In vehicle construction, LCP is used primarily for electrical and electronic components in temperature-stressed areas. Examples are connectors, sensor components, bobbins and housing components.

Before use, resistance to fuels, oils, coolants and other vehicle media as well as the mechanical requirements of the component must be checked.

Aerospace

In aerospace, LCP can be used for lightweight electrical insulation and connection components. In addition to temperature and media resistance, requirements for flame behaviour, smoke gas development, outgassing and traceability are often relevant.

Suitability must be demonstrated on the basis of the specific material type and the respective applicable aerospace requirements.

Medical technology

LCP can be of interest for small, precise components in medical technology. These include, for example, components in analytical devices, sensors, instruments or medical electronic systems.

However, LCP must not be described across the board as biocompatible or suitable for every sterilisation method. For medical applications, a correspondingly tested material type, documented biocompatibility and approval for the intended sterilisation method are required.

Industrial sensor technology and automation

The combination of dimensional accuracy, electrical insulation and temperature resistance makes LCP of interest for sensors, actuators, plug-in systems and other components in industrial automation. In systems with chemical exposure, media resistance must be checked for the specific operating case.

LCP compared with PEEK, PPS and PTFE

LCP is not fundamentally superior to other high-performance plastics. The materials solve different technical tasks.

Criterion	LCP	PEEK	PPS	PTFE
Thin-walled injection moulding	Very good	Good	Good	Unsuitable for classic injection moulding
Dimensional stability	Very high, but direction-dependent	Very high	High	Limited by creep tendency
Mechanical load capacity	High in the orientation direction	Very high and balanced	High, often reinforced	Comparatively low
Chemical resistance	Very good	Very good	Very good	Exceptionally high
Sliding and anti-adhesive properties	Not a primary advantage	Can be well modified	Type-dependent	Very good
Availability as semi-finished product	Limited	Good	Good	Very good
Typical strength	Miniaturised electronic components	Highly stressed precision parts	Chemically and thermally stressed series parts	Seals, insulation and sliding components

PEEK plastic is often more suitable when high mechanical load capacity in several directions, toughness, wear resistance or production from semi-finished products is required.

PPS plastic offers a good combination of chemical resistance, temperature resistance and cost-effectiveness for industrial series parts.

PTFE plastic is particularly interesting when a very low coefficient of friction, anti-adhesive properties or exceptionally broad chemical resistance are more important than high strength and dimensional accuracy.

Advantages of LCP plastic

• very good flowability for thin-walled components
• high heat deflection temperature
• low water absorption
• high dimensional accuracy
• good electrical insulating properties
• good chemical resistance
• low moulded part shrinkage
• high stiffness with reinforced types
• suitable for complex miniature components
• flame retardant with suitable types

Disadvantages and limits of LCP

The special properties of the material also bring constructive and economic limitations:

• strongly direction-dependent mechanical properties
• critical weld lines with unfavourable mould design
• partly low toughness transverse to the direction of flow
• higher material price than standard plastics
• limited availability as sheet or rod
• demanding bondability and coatability
• increased tool wear with heavily filled types
• type-dependent approvals and property profiles

When is LCP the right material?

LCP is particularly interesting when a component must be very small, thin-walled, dimensionally accurate and electrically insulating and at the same time must withstand increased process temperatures. This particularly often applies to connectors and other series components in electronics.

When selecting the material, at least the following questions should be answered:

• What continuous and peak temperatures occur?
• What mechanical forces act in which direction?
• What media come into contact with the component?
• What electrical characteristics are required?
• What wall thicknesses and tolerances are intended?
• Are there requirements for flame retardancy or approvals?
• Is an injection-moulded part or a machined finished part required?
• What quantity is to be manufactured economically?

If high toughness, pronounced wear resistance or good availability as a semi-finished product are decisive, another high-performance plastic may be more suitable. The selection should therefore always be made on the basis of the specific requirement specification.

LCP components and material selection with Martan Plastics

Martan Plastics supports industrial companies in the selection of suitable plastic materials and in the technical assessment of individual components. Among other things, temperature, media contact, mechanical load, electrical requirements, geometry, tolerances and quantity are taken into account.

For a well-founded assessment, a drawing or a 3D model, the intended application, the required quantity as well as existing material and approval specifications are ideally provided. On this basis, it can be assessed whether LCP or an alternative high-performance plastic represents the technically and economically appropriate solution.

Frequently asked questions about LCP plastic

What does the abbreviation LCP stand for?

LCP stands for Liquid Crystal Polymer. It is a group of aromatic thermoplastic high-performance plastics.

Is LCP a thermoplastic?

Yes. LCP is a thermoplastic plastic and can be melted and processed at a suitable temperature. The most important processing method is injection moulding.

How temperature-resistant is LCP?

The temperature resistance depends strongly on the specific LCP type, the reinforcement and the duration of load. Many types withstand high soldering temperatures for short periods. The permissible continuous service temperature must be taken from the respective technical data sheet.

Why is LCP used for connectors?

LCP can be processed with very thin walls, absorbs little water and offers good electrical insulating properties. In addition, suitable types are dimensionally accurate, flame retardant and resistant to the temperatures of modern soldering processes.

Is LCP chemically resistant?

LCP is resistant to many industrial chemicals. However, suitability depends on the medium, concentration, temperature, duration of exposure and material type and must be checked for the specific application.

Is LCP suitable for medical applications?

Certain LCP types can be suitable for medical technology applications. However, a tested material type, the appropriate biocompatibility evidence and approval for the intended sterilisation method are required.

Can LCP be milled or turned?

In principle, machining is possible. However, LCP is mostly used as an injection-moulded part, as semi-finished products are only available to a limited extent. The feasibility depends on the material type, dimensions, tolerances and component geometry.

What is the difference between LCP and PEEK?

LCP is particularly suitable for thin-walled, precise injection-moulded parts in electronics. PEEK often offers more balanced mechanical load capacity, high toughness and better availability as a semi-finished product for machined finished parts.

What information is required for an LCP enquiry?

A technical drawing or a 3D model, quantity, tolerances, temperature range, media contact, mechanical load, electrical requirements and required approvals are helpful. This allows the suitable LCP type or a possible material alternative to be checked in a targeted manner.

How is LCP plastic processed?

LCP plastic is predominantly processed by injection moulding. Due to its low melt viscosity, the material is particularly suitable for thin-walled and complex moulded parts. Depending on the LCP type, extrusion and machining are also possible.