What Is Every Layer Interconnect PCB?

As PCBs become increasingly thinner and get more and more layers, new methods are needed to enhance the density of interconnects. Every layer interconnect (ELIC) is the name of a modern HDI routing and stackup design technique that is perhaps the most intricate technique in use today.

To route signals on high density interconnects between any group of layers in the PCB, this routing method simply extends microvias throughout the whole PCB stackup. While this may appear as a harmless approach, it, however, imposes limitations on the PCB's production procedure and material sets. In this piece, we'll examine ELIC in greater detail.

What Is Every Layer Interconnect (ELIC) PCB?

Every Layer Interconnect (ELIC) is the name for a technology that enables PCB designers to design and manufacture extremely flexible and thin PCBs with great functional density. These cutting-edge HDI boards have numerous layers of stacked, copper-filled in-pad microvias that allow for even more intricate interconnections.

Some people also refer to ELIC as any-layer HDI. When using a PCB based on ELIC technology, every layer has its own laser-drilled, copper-filled microvia. Only microvias filled with copper are used in ELIC PCBs for the purpose of establishing a connection through each layer. Once the layers are stacked, this enables connections to be created between any two layers of the PCB. In addition to providing more flexibility, this also enables designers to maximize the density of interconnects.

Since all connections on the board are made during the first building, through-hole vias are no longer necessary. Since the ELIC uses a copper-filled construction, VIPPO or any other plating technique is no longer necessary for filled vias. According to IPC standards, the stacked microvias should not span across the entire PCB stackup since it can compromise the reliability of the microvias.

Not all fabricators can provide yield for ELIC PCBs free of latent reflow faults. Make sure to implement their DFM guidelines when choosing a manufacturer who can offer these guarantees if you want to make sure your board will meet quality and acceptance standards.

Hemeixin is one of the leading electronics manufacturing businesses that provides ELIC PCBs tailored specifically to your needs. Our manufacturing process is compliant with all DFM rules and guarantees that your PCBs pass the acceptance and quality criteria.

DFM for ELIC PCBs

Floor-planning an HDI PCB that will employ ELIC should generally adhere to a few straightforward DFM guidelines. A qualified manufacturer will always be adherent of incorporating these general rules into their process while being considerate of your application requirements and needs, just as Hemeixin does. Following are the main DFM rules for ELIC PCBs:

• For the fabricated bare board to be reliable, use the proper microvia aspect ratio.
• To enable you to use your fanout approach, carefully coordinate layer thickness with clearance and trace width for impedance regulated lines.
• To avoid voiding/dimpling, be careful to provide filled microvias in the interior layers.
• The device's layer arrangement must be symmetrical throughout.

Generally, these DFM rules help with the standardization of components and materials, the reduction of the number of parts, and the minimization of the number of manufacturing procedures needed on parts during assembly.

ELIC PCB Applications

The improved flexibility and sophistication of ELIC PCBs has allowed them to replace the outdated rigid flex PCBs used in many of our daily-life devices such as computers and laptops. Specifically speaking, ELIC PCBs have found a home in memory cards, GPUs, and other components that go inside computers, gaming consoles, cameras, and more.

Additionally, ELIC PCBs can also be utilized in the manufacturing of modern tablets, smartwatches, and smartphones. High pin count and fine pitch components are frequently needed for these applications. These boards also usually have 10 layers or more. The benefit of using ELIC PCBs for these applications is that designers can route the necessary interconnects on boards within a compact footprint.

Furthermore, high-speed applications that demand high IO density, including in FPGAs where several interfaces are being instantiated in the device, also often employ ELIC PCB stackups. Some boards that need to support RF routing on PTFE materials may also employ ELIC. Since routes can sometimes be brief, return loss and impedance mismatch will predominate in these lines in any case.

These boards can be routed across layers without leaving stubs because backdrilling is not required. Keep in mind, however, that the length of the useful trace will be limited as a result of the dominance of dielectric losses on longer pathways. Consider these points as you choose the materials for your HDI board.

Some HDI rigid-flex PCBs now frequently use ELIC as well. Folded rigid-flex boards and ELIC-capable PCBs are often used together in a single package. This allows the package sizes to be further reduced, provided that the bend region, if present, is chosen to minimize stress on the microvia stacks.

Flex ribbons can be designed using ELIC as well. While the designing technique for the flex remains the same as the standard design procedure, the use of ELIC enables designers to house the ribbons into smaller PCBs.

In high-speed, high-density designs, inner signal layers tend to have multiple power/ground planes which can assist insulate signal layers from one another and mitigate crosstalk. By blocking off excess radiation, this promotes EMC compliance. Creative layout techniques in ELIC PCBs can also assist in keeping signal layer counts low and allow the usage of more ground, which has the dual effect of lowering crosstalk and EMI.

Conclusion

Every Layer Interconnect (ELIC) is a PCB technology that enables designers to create incredibly thin and flexible PCBs with high functional densities. These state-of-the-art HDI boards support even more complex interconnections thanks to their layers of stacked, copper-filled in-pad microvias. This has allowed them to be used in many of the modern devices we use today, such as smartphones, wearables, graphic cards, and more.

Hemeixin PCB is a leading electronics manufacturing company that specializes in a variety of PCBs and circuitry. Our services include semi rigid-flex PCB, rigid PCB, Flex PCB, and of course, Every Layer Interconnect (ELIC) PCBs. To get a quote on our services or learn how we can help you, contact us today!