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Game-Changer in EV Battery Manufacturing: Ennovi’s Flexible Die-cut Circuit (FDC)

Overview

Electronically controlled automotives have come a long way since their inception. Today, electric vehicles control functions such as GPS, anti-lock brakes, and vehicle stability control, among many others. Continued progress in EV technology has given rise to the development of self-driving vehicles, infrastructure information sharing, automatic parking, and even major changes in the powertrain for future vehicles.

Vehicle electrification also signals a deviation from the use of fossil fuels, but to do this, a total modification of the powertrain and other electronic components for EV functionality.

Electric vehicles need tight integration of various functions, which are made up of components such as the control printed circuit board (PCB). This refers to the medium connecting, or ‘wiring’, components to one another in a circuit. It may resemble a sandwich structure composed of conductive and insulating layers. PCBs serve as the electrical connection and mechanical support to circuit components.

Flexible die-cut circuit vs. flexible printed circuit: what’s the difference?

A flexible circuit is a type of PCB that features a pattern of conductors on a bendable film, which in turn acts as an insulating base material. Flexible circuits are needed for the quicker construction of an electronic device.

The flexible circuit is a core part of an EV battery cell contacting system. ENNOVI launched what is called the flexible die-cut circuit (FDC) technology, a more sustainable way to produce flexible circuits for low voltage signals in EV battery cell contacting systems.

These are manufactured reel-to-reel with no size limitations while still exhibiting similar performance to that of flexible printed circuits (FPCs). 

Meanwhile, FPCs are traditionally used in battery cell contacting systems. The problem, however, is that it tends to be the most expensive component in current collector assembly (CCA). 

FPCs are produced through a multi-stage, batch photolithography process to etch copper traces for the flexible circuit. These use corrosive chemicals to dissolve the unneeded copper, which is time- and energy-consuming and difficult to recycle. Furthermore, there is a size limitation of 600x600mm for these circuits.

What are the benefits of FDC technology?

FDC technology is a sustainable, flexible flat device with fewer processes, reduced production time, and lower costs. It is ideal for low voltage solutions.

FDC technology is cost-efficient, saving 25 to 50% of costs, without cutting corners in terms of operations. There is a faster cycle time as it cuts production process steps by 50%, compared to FPC. Recycling too, is made easier. This technology promotes sustainability due to the recyclable process and recycling of clean copper waste material.

What are the features of FDCs?

What makes this technology cutting-edge? Below are some features of FDC technology:

Dielectric material options

The dielectric layer of flexible die-cut circuits comes in two options: polyimide (PI) and polyethylene terephthalate (PET).

PI has excellent flexibility, tensile strength, thermal conductivity, and chemical resistance. Meanwhile, PET also has good flexibility as well as high chemical and moisture resistance. 

Additionally, FDC technology offers cold and hot lamination processes.

Traces

FDC technology provides high-precision die-cutting that results in tight tolerances, while continuous copper traces provide a reliable signal. The double stack layer traces have the capability to enhance packaging efficiency.

Fuses

Based on what the customer requires, FDC technology provides built-in fuse traces or surface mount (SMT) fuses.

Other features include: thermal sensors, to which off-the-shelf negative temperature coefficient (NTC) can be added via SMT and reflow soldering processes; current collector tabs, made of nickel soldered to copper traces to meet tight packaging space requirements and to achieve reliable signals; and connectors that are compatible with copper traces, as well as solder connector tabs to FDC copper traces.

What are the applications of FDCs?

Flexible die-cut circuit technology has a vast array of applications ranging from electric vehicles, commercial transportation, energy storage systems, and personal mobility.

ENNOVI, a leader in mobility electrification solutions, employs FDC in CellConnect-Prism, their prismatic cell contacting system. 

ENNOVI-CellConnect-Prism allows for the smooth integration of individual prismatic cells to form larger battery modules or advanced cell-to-pack (CTP) and cell-to-chassis (CTC) configurations. Often, the most expensive component in EVs is the battery pack. CellConnect-Prism combines step processes into a one-stop lamination process, thereby saving costs by up to 15%.

It also renders unnecessary traditional insulation methods by integrating voltage and temperature sensors into the assembly, optimizing material usage and production efficiency.

The streamlined assembly process enables the cell contacting system to get rid of inefficiencies and speed up battery pack production, all the while cutting costs and improving usage of materials. 

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