DuPont streamlines bus bar overmolding for xEV High Voltage Components

DuPont Mobility & Materials is breaking new ground for manufacturers of xEV components with a combined material-process-service solution for overmolding bus bars with Zytel® HTN material. Bus bars are a workhorse component essential for distributing power in xEV batteries, motors, and power electronics.

Laminated metal bus bars are found in virtually every xEV system. They transfer electrical energy from high-power battery packs to inverters, so that it can be converted to AC electricity the engine can use. With the right materials, a bus bar can enhance a battery’s thermal management and power distribution systems. However, it must be adequately insulated if the battery overheats, a condition known as thermal runaway.

“Although small, bus bar components are numerous, and also critical to the efficiency and durability of xEV batteries, motors, and power electronics,” said Giacomo Parisi, marketing director for automotive electrification at DuPont. “Our goal is to provide an excellent material for the application, along with assisting customers in their bus bar design and overmolding, to help them achieve their performance and production goals.”

Bus bars within xEV batteries must meet several requirements, including:

•          Resistance to thermal runaway without loss of function

•          Qualification via demanding thermal cycling and electrical tests

•          Efficient production to reduce manufacturing time and cost

•          Stable orange color to indicate high voltage, even after prolonged exposure to high temperatures

Utilizing a host of production equipment, lab testing, and engineering capabilities at these facilities, the company has fine-tuned an overmolding process for bus bars that incorporates Zytel® HTN material along with robust technical and processing support. Using sophisticated computer-aided analysis tools, DuPont collaborates with customers to reduce manufacturing time and cost, yet maintain performance and safety standards.

Zytel® HTN has been identified as an elegant material solution in this area. For example, safety standards dictate that bus bars maintain a stable orange color indicating high voltage, even after repeated exposure to high heat. Zytel® HTN accelerated aging testing shows no noticeable color shifts, even at 130°C. It also contributes insulative properties for safer thermal runaway, and easily overmolds onto aluminum or copper, the most common bus bar metals.

Additionally, Zytel® HTN insulation materials for bus bars resist multiple thermal shock cycles (typically 1000 cycles) at the temperatures (-40°C to 150°C) normally needed for motors and power electronics applications. This means the material resists cracks after being overmolded onto metal conductors. Further, the material has excellent chemical resistance to the fluids used for thermal management and a high comparative tracking index (CTI) at elevated temperatures.

DuPont Mobility & Materials will showcase advances in bus bar overmolding and other cutting-edge solutions and technology innovations in Hall 6, Stand C43 at the upcoming K 2022. Considered the world’s leading trade fair for the plastics and rubber industry, this triennial international event takes place from 19 to 26 October in Düsseldorf, Germany.