Current Collector Assembly for Lithium-Ion Batteries [12 Steps]

By 2035, the European Union will ban the sales of gas and diesel cars. Electric vehicles (EVs) are the future of automotive. As you know, currently, EVs' power source is the lithium-ion battery pack. The current collectors (CCs) module, made from a flexible printed circuit board assembly (PCBA) module, is a necessary component of the lithium battery system.

This article reveals the whole assembly process for the CCs module, from flexible PCB fabrication, and flexible PCB assembly, to current collector assembly and inspections.

For a quick look, you can see the video below to see flex PCB fabrication and assembly and CCs module assembly.

Dive to see details of flex PCBA and current collector assembly below:

Part 1: CCs Module for Lithium Battery Pack

A current collectors (CCs) module is the cover of the lithium-ion battery pack of EVs. It comprises a flexible PCBA module, black films, and nickel sheets. And it is custom-made according to the placement of your batteries.

A CCs module collects electric currents from the lithium-ion batteries to drive the EV or from the charging station to the batteries to charge. The flexible PCBA embedded in or on the surface of the CCs module collects signals of the lithium batteries and transfers them to the battery management system (BMS) so that the BMS can manage the status of the batteries.

Part 2: Current Collector Assembly Methods

The current collector assembly for lithium-ion batteries is assembling the flex PCBA module, black films, and nickel sheets to be a CCs module. There are two methods of current collector assembly: thermal lamination and blister tray processing.

This is a CCs module that we fabricated by thermal laminating the flex PCBA, black films, and nickel sheets. The flexible PCBA is embedded in the CCs.

We manufactured the above CCs module by fixing the flex PCBA at the bottom of black films and nickel sheets with screw connecting and blister processing.

Before the current collector assembly, we completed flex PCBA manufacturing and nickel sheet mold opening. The current collector assembly step is just laminating them to be whole.

As you can see, the most critical process of current collector assembly is flex PCBA manufacturing, which is made by surface mounting small nickel sheets and connectors on a flexible printed circuit board and glue dispensing. You can check how we fabricate and test the flexible PCBA in Part 4.

Part 3: One-Stop Current Collector Assembly Manufacturer

PCBONLINE is a one-stop flexible PCB manufacturer for automotive, medical, industrial, and consumer electronics. We can fabricate the flexible PCB assemblies and further process them into current collectors for lithium-ion battery packs of EVs.

We are a source manufacturer and complete the current collector assembly process independently, including fabricating flexible PCBs (FPC), flex PCB assembly, nickel sheet mold opening, thermal laminating the CCs, and testing.

By working with PCBONLINE for current collector assembly, you can enjoy many benefits:

PCBONLINE has rich experience in fabricating FPC modules and further processing them into CCs modules. If you need flex PCB assembly or current collector modules for lithium-ion batteries, you can send your Gerber to info@pcbonline.com for a quote. We will offer you one-on-one engineering support throughout your project and free samples for bulky production.

Part 4: Flexible PCBA and Current Collector Assembly Process and Testing

The fabrication of a flexible PCBA module is the most important process of current collector assembly. The flex PCBA and CCs module manufacturing process from PCBONINE is revealed step by step.

Step 1. Cut lamination

PCBONLINE completes the fabrication and assembly of flex PCBs at one-stop. The first step is to prepare the flexible PCB laminates and cut them in tolls to be at the required width.

Step 2. Circuit generation

Circuit generation is in the toll-to-toll way, which means we etch circuits while rolling up the copper foil toll. The long circuit generation line includes procedures of exposing > developing > checking > etching > checking > film stripping > checking. The maximum width of the copper foil we can etch is 250mm.

Step 3. Surface finish

OSP is the most affordable and common surface finish for flexible PCBs. Besides OSP, we can also apply the other surface finish immersion gold on flex PCBs.

Step 4. Automatic optical inspection (AOI)

After circuit generation, we have to make sure the circuits gave no surface mistakes, such as short or open circuits.

Step 5. Cutting coverlay

Coverlay is the solder mask of flexible PCBs to protect the circuits and materials. We need to cut the coverlay films to match the size of the flex PCB production panel. It is done in an automatic machine without human touching.

Step 6. Attaching coverlay

This is also done automatically without human touching. The coverlay films are attached to the copper foil while soldering the mask opening.

Step 7. Lamination

At this step, we put the flex PCBs in an oven to laminate the flex boards at high temperatures and pressure so that the copper layers and coverlay films form a whole.

Step 8. Silkscreen printing

At this step, we silkscreen print the characters, component codes, company names, and quality icons on the flex PCBs as you want.

Step 9. Electrical testing

Before electrical testing, we have already fabricated the custom jigs for testing the flex PCBs. At this step, we put the flex PCBs on the jigs for electrical testing to ensure the circuits work properly.

Step 10. Surface-mount (SMT) assembly

Before SMT assembly, we have already made custom jigs for fixing the flexible PCBs during the assembly process. We place the flex PCB panel in a jig and then place it in an SMT assembly machine. The machine picks and places components on the flex PCB to become a flex PCBA. For current collector uses, the components of a flex PCBA include small nickel sheets and connectors. We assemble components on the flex PCB while glue dispensing it.

Step 11. Current collector assembly

Before the current collector assembly, we completed the nickel sheets mold opening and prepared black films. At this step, we can thermally laminate the black films and nickel sheets on top and bottom of the flex PCBA to make it a CCs module. The other way is to laminate the nickel sheets and black films and then fix the flex PCBA at the bottom with screws and the blister trays process to make them a CCs module.

Step 12. Testing

PCBONLINE has comprehensive tests to make sure the flexible PCBA or CCs modules we manufactured for you have the best quality. The tests include electric tension testing, bending testing, hand sweat testing, environmental protection testing, metallographic microscope inspection, bridge testing, fuse fusing testing, DC resistance inspection, withstand voltage testing, impedance testing, and salt spray testing.

During the flex PCB fabrication, we can add stiffeners to the boards. The stiffener materials include polyimide, FR4, and stainless steel. Flex PCBs used in the current collector module for lithium-ion batteries for EVs have only one circuit layer and no plating through holes, so the above manufacturing process is simpler. PCBONLINE also fabricates multilayer flex PCBs and transparent flex PCBs, and you can read our previous article to know the fabrication process of flex PCBs that are more complex.

Conclusion

Current collector assembly is a process of manufacturing the flexible PCBA and laminating with black films and nickel sheets to make them a CCs module. Automotive electronics are not complex to fabricate, but the quality standard is high because it involves human safety. If you are an automotive original equipment manufacturer and need flex PCBA and current collector assembly, don't miss the source factory manufacturer PCBONLNE.

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