Over-Molding for Electrical Assemblies

Over-molding is the process of surrounding a component with plastic. In the case of electrical assemblies, a plastic resin is injected around critical electrical connections under controlled conditions. The over-molding of cables improves their overall longevity and reliability, and oftentimes reduces the total cost of ownership.

KEY ATTRIBUTES:

Over-molding creates a product that is highly robust and durable with several key attributes.

• Ingress protection: During the over-molding process, the materials used and the mold configuration are both highly controlled. This allows a material bond to be formed around cables and connections, which in turn creates watertight joints. Properly molded connectors can typically pass stringent industry standards.

• Vibration protection: The space around the internal components of an electrical assembly are completely filled by over-molding, leaving no air gaps. This prevents the electrical components from shifting within the assembly, thus helping eliminate fatigue and other types of damage.

• Protection from physical abuse: Certain molding materials are better than others at providing extreme resistance to physical abuse. Polyurethane is often used for harsh and rugged environments.

• Compact assembly: Over-molding produces a final product that is generally smaller than other types of assembly methods, such as mechanical back-shells or enclosures.

• Integration: The over-mold process can accommodate additional items into the assembly. Some of these items include diodes for reverse polarity protection, resistors for circuit analysis, pc board assemblies, electrical switches, and small steel cables.

• Strain and flex relief: The flex life of an over-molded assembly is generally enhanced by a factor of two times. Some types of strain relief geometry include: straight, 45 degrees and 90 degrees.

• Cosmetic features: In addition to the aesthetic finish, the over-mold offers opportunities for performance additives and cost-reduction benefits. Product identification, color-coding, and connector orientation features can be added to the final product.

Overmolded D Sub Cable	Circuit Board
Overmolded Circuit Board	Close-up of Strain Relief

TYPES OF OVER-MOLDING:

There are two primary processes for over-molding: high pressure and low pressure. High-pressure molding offers the widest range of material choices, however, low-pressure molding allows delicate components to be molded without damage. Low-pressure molding utilizes an adhesive thermoplastic that provides sealing and a durable outer surface.

AND FINALLY…

If you still have questions regarding over-molding for electrical components, please feel free to contact us for additional information.