Flux AI Tutorial - Automatic Micro Via Placement

Introduction

In the advanced realm of PCB design, efficiency in space utilization is paramount. As engineers strive for more compact and high-performance devices, traditional through-hole vias often fall short in achieving the required interconnect density. This is where High-Density Interconnect (HDI) design plays a crucial role. HDI allows for the integration of more functionality within smaller footprints by utilizing advanced via technology, including micro vias, blind vias, and buried vias.

Understanding Vias

Blind Vias

Blind vias start at one of the outer layers of the PCB and extend to an inner layer. They are particularly useful for connecting surface-mounted components to inner layers without necessitating traces that traverse the entire board. Blind vias can be drilled after board assembly, although they can also be manufactured before the layers are connected.

Buried Vias

As the name suggests, buried vias are completely confined within the inner layers of the PCB. They are essential for connecting internal layers without consuming surface real estate, making them highly functional for dense designs. Typically, buried vias are drilled before the board undergoes complete assembly.

Micro Vias

Micro vias are exceptionally small and have diameters ranging from 25 to 150 micrometers. These vias typically require laser drilling for precision. However, the diameter is confined by the hole depth-to-hole diameter aspect ratio, with different manufacturers having varying capabilities regarding PCB production.

Configurations of Vias

Vias can be organized in two main configurations:

1. Stacked Vias - Where vias are perfectly aligned and placed directly over one another across multiple layers.
2. Staggered Vias - Which are offset across different layers, resembling steps on a staircase.

Using Flux for Via Management

Now that we have a solid grasp of the different types of vias, let’s delve into how to effectively manage them in Flux.

Creating a New Project

1. Start by navigating to your profile and selecting "New Project" to create a blank project.
2. Once the project is created, add a few schematic components to facilitate the demonstration of smart via placement.

Configuring the Stackup

• In the PCB editor, access the layout from the object tree list.
• In the inspect panel on the right, locate the object-specific rules section. Click "Add" and search for "stackup."
• Choose the desired stackup configuration from the drop-down menu or click the pen icon to directly open the stackup editor for advanced control.

Managing Via Configurations

In the stackup editor, you can manage layers as well as via configurations:

• Add or delete layers as needed.
• For added via configurations, set parameters including start and end layers, drill types, and sizes. Your chosen configurations will feature in future layout designs.

Prioritizing Vias

The position of the via configurations from left to right determines their priority during routing. Flux will utilize the highest priority via for connections unless specified otherwise.

Using Smart Vias

You can place smart vias in several ways during routing:

• Right-click on the canvas and choose from layer options.
• Use the shortcut key "V" for a cyclic placement of vias.
• Access the object list, right-click, go to "Add," and then select "Smart Via."

Changing Via Types

In Flux, you can alter the type of via a smart via uses without needing to adjust the via prioritization manually. By selecting the smart via, you can change its properties in the options toolbar, allowing Flux to automatically switch to the next highest priority via that fulfills the necessary electrical connection.

This setup allows for highly efficient workflows in compact designs, greatly enhancing productivity and reducing design times.

Keywords

• PCB Design
• HDI
• Vias
• Blind Vias
• Buried Vias
• Micro Vias
• Smart Vias
• Routing
• Stackup Configurations

FAQ

What are the types of vias used in PCB design?

The main types of vias are blind vias, buried vias, and micro vias.

How can I create a new project in Flux?

Go to your profile, select "New Project," and choose to create a blank project.

What is the benefit of using HDI design?

HDI designs allow for higher interconnect densities, enabling more functionality in smaller board footprints.

How do I prioritize vias in my PCB design?

The prioritization of vias is determined by their position in the via configurations, arranged from left to right.

Can I change the type of via used in a smart via without reconfiguring the stackup?

Yes, you can modify the via type directly in the options toolbar by selecting the smart via and adjusting its properties.