Overmolded busbars in automotive

As an engineering service provider, M.TEC develops solutions in the field of overmolded busbars for electromobility.

Overmolded automotive busbar - CAD view

Overmolded automotive busbar (Engineering by M.TEC)

Design aspects and goals: Highly stressed hybrid component, Highest safety requirements – Safe, Compact, Powerful, Precise, Robust

Services by M.TEC in this project:

In the automotive sector, the overmolded busbar is used to safely conduct the electrical current between high-voltage storage unit, control unit, drive and charging unit. Key challenges in development & design:

Electrical separation / insulation 

The main functions of the busbar are the safe, short-circuit-free conduction of electrical energy between the drive and charging components and the protection of assembly and workshop personnel from touching live components.

Functional performance and manufacturability contradictions

Thermal shock test, thermal shock resistance

Automotive components are subjected to severe temperature cycling and thermal shock tests. Busbars are made of several materials (copper, thermoplastics, elastomers) with very different thermal properties (coefficient of thermal expansion). These thermal shock tests, in which the components are stressed by storage in hot and cold environments, can lead to damage to the components and failure to pass the tests. Possible faults or damage include excessive component distortion, cracks in the plastic material or a separation of the connection between plastic and copper. The result is loss of the insulation effect, penetration of moisture and thus corrosion and electrical short circuits.

Early validation of technical concepts

Powering tests

Powering tests of the busbars simulate driving cycles and charging cycles under different climatic conditions in a particularly sharp form. In doing so, large temperature differences and changes are deliberately generated in the busbar, which result from the driving operation.

Due to the different materials the busbars are made of, large thermal stresses occur in the components. This can lead to faults and damage, such as severe component distortion, cracks in the plastic or detachment of the plastic from the copper conductor. The essential component functions are thereby disturbed or no longer exist, the components fail and the tests are not passed.

Powering tests: Realistic predictions using thermal simulations

Sealing / tightness

If the seal is not completely tight, media can penetrate from the outside (moisture, dust, dirt particles, salts, cleaning agents, oils, greases, brake fluid, etc.) This results in malfunctions or damage to the conductor rail and connected components. In the worst case, a short circuit may occur, which also damages the battery and electronics. Other types of damage that develop over a longer period of time and ultimately lead to functional failure include creeping corrosion and wear on plug contacts. As a rule, the seal must function just as reliably as before even after the component has been removed for maintenance purposes and reassembled.

Seal design - warpage and tolerances

High durability

The busbar must function faultlessly throughout its service life. If a failure occurs, high repair costs are incurred in individual cases and in the event of a systemic fault, recall actions must be carried out. The reasons for failure are the stresses and strains during installation in the vehicle, driving operation and environmental influences. During operation, the busbar is mainly subjected to thermal loads and mechanical forces, e. g. vibrations, impacts or torsion. Environmental pollution is mainly caused by the influence of media such as water, dust, sand, salt and chemicals, often in combination with climatic influences.

Durability: Understanding loads and material properties correctly

Phoenix Contact
Your Contact
Ulf Seefeldt
Ulf Seefeldt
Business Development Manager
+49 2407 9573-7361
+49 2407 9573-7325
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