Frequently asked questions on Low Pressure Overmoulding

How long is a typical injection cycle?

The moulding cycle is dependent on the size and material section thickness of

the component and the type of equipment being used. Typical cycle times range

from 15 to 45 seconds. Multiple cavity moulds can be used to reduce the actual

processing time per part.

Can you over-mould a PCB with surface mounted components?

 Yes, The relativity low processing temperatures of the polyamide materials

typically 218°C (425°F) are much lower than the reflow soldering temperatures.

Tests show that material injected at 218°C (425°F) typically will cool down to

less than 150°C (300°F) by the time it reaches the board.

Can the overmoulded assembly be distorted in any way within this process?

No, not if proper design guidelines are followed. (Uneven encapsulation such as

a very thick material section on one side of a PCB with a thin layer on the other

could result in warping).

Will the part maintain dimensional stability after moulding?

Shrinkage ranges from 1 to 1.5% for the different Macromelt materials.

How can air bubbles be avoided in the final moulded part?

Ensuring that the mould-set is vented correctly and optimising the injection

profile is the key to avoiding air bubbles. Densely populated circuit boards may

require several steps in the injection profile to avoid any “shadow effects” behind

components. We would typically start by optimising flow with translucent

materials to detect where voids occur and then change to black materials for


Can batteries be over-moulded without reducing their effectiveness?

Many types of batteries have been successfully over-moulded with Macromelt.

However, simple prototype over-moulding for a particular battery is

recommended before starting full-scale production.

Which wires, cables, circuit boards and solder masks do these materials adhere to?

Macromelt® adheres well to most substrates including PVC wires and PCB’s.

Henkel Corporation offers adhesion testing of their Macromelt® materials on any

specific substrates; this type of testing will identify the most suitable material for

a given application.

When should this technology be considered for grommets and strain relief moulding?

The adhesive properties of the Macromelt® material will offer great seal and

strain relief to most wire and cable materials. When true strain relief is needed

especially for sensitive cables/applications such as Cat 6 patch cords and

connectors, the Macromelt® materials are superior.

Are over-moulded parts water proof?

Over-moulded components will typically meet or exceed IP 67 rating for the type

of environment it is capable of operating in. This means they are dust tight and

protected against the effects of immersion. The selection of Macromelt® material

 grade is critical as there are different degrees of water resistance.

Why do you recommend Low Pressure Overmoulding over traditional potting or other encapsulation processes?

LPO is a 3 step process ( insert assembly > overmould > test ) versus an 8 step process for potting. This removal of process steps reduces manufacturing time, overall labour and material costs and improves throughput, resulting in increased ROI. There is zero waste, scrap is often recyclable and the process is environmentally friendly, giving off no toxic fumes.

What materials do you use or recommend?

We use Thermoplasitc polymers ( Polyamide and Polyolefin )  i.e. polymers that become pliable or mouldable above a specific temperature and return to a solid state on cooling. They also possess excellent adhesive, moisture and UV light resistance properties, are quick to cure and are the preferred materials for low pressure overmoulding.

The performance of these materials varies according to the options chosen and require careful selection relating to their properties ( e.g solvent or moisture resistance ), in order to meet the environmental conditions the finished product resides in.

What type of mould tool do you recommend?

For most applications we recommend aluminium mould tools, which are quicker and less costly to produce than steel. They offer excellent performance for volumes typically from 100 – 500,000, for simple to complex moulding applications that need production quickly on a tight budget. Where there are no cost constraints and volumes are in the millions, steel mould tools provide better longevity and would be recommended.

Can you incorporate branding/logos on my moulded assembly?

Yes, logos, product ID’s and text can be engraved on mould tools either in recessed or protruding format.

Can you produce overmoulded assemblies in different colours?

Amber or black are the standard colour choices available. Some custom colours are available. Please contact us for details.

What is the maximum size of overmoulded assembly you can make?

Circa 110mm x 90mm

Are the overmoulded assemblies you produce RoHS/WEEE compliant?

Yes, we use suppliers that only ship RoHS and WEEE compliant materials.

Can you use existing 3D CAD data to produce a mould tool?

Yes, our toolmaking associates have been crafting precision low pressure moulding tools in aluminium that have been used world-wide since the process evolved during the mid 90’s. They have the skills to create a precision mould tool by importing 3D CAD model data using the STEP ( ISO 10303) standard to network directly with their state of the art four and five axis CNC mills. They can work to tolerances expressed in microns if necessary.

What information do you need in order to quote if no CAD data exists?

We can usually quote if you can provide a sample or a drawing or picture of the assembly you require overmoulding, plus its dimensions. We need to know what environment the overmoulded product will be subject to in order to determine its properties required ( e.g. heat or UV light resistance etc.  ). We also need to know batch sizes and frequency required.

Why should we use EC Electronics as our preferred supplier?

Our background in electronics overmoulding goes back many years, providing a wealth of experience in overmoulding Cable Assemblies to provide connector sealing and strain relief.

Today, in addition to overmoulding Cable Assemblies, we provide the latest and most cost effective moulding process for the protection and encapsulation of Printed Circuit Board Assemblies ( PCB’s ).

Low Pressure Overmoulding ( LPO ) protects sensitive electronic components on assembled printed circuit boards from moisture, dust, vibration and after market tampering. It leaves your electronics undamaged, overmoulds directly onto your electronics and seals to IP67 rating. There is no need for a separate housing or potting.

LPO is also used to provide protection for Cable Assemblies, where connector sealing and strain relief is needed.

EC Electronics is the first contract manufacturer in the UK to offer LPO as a complete turnkey service, embracing PCB & Cable Assembly, Electrical Test and Overmoulding.