The Tech Blog

BackToBasics: PCB Vias and their types

Posted under Back to Basics, Technology on September 8th, 2024 by Amaldev

This is one topic I wish someone had taught me when I first started designing boards. Back then, finding content online wasn’t as easy as it is today. Vias are essentially small holes that create electrical connections between different layers of a PCB. Whether a PCB has just 1 layer or several, vias are the key to connecting layers and routing signals between them.

The most common via is the Through-hole via, drilled from the top to the bottom layer, connecting one or more layers in between. It doesn’t need to connect all layers, but the hole goes completely through the PCB. It’s the cheapest option due to easy manufacturing (drill once through all layers). However, it takes up space, and you can’t place parts or pads on both sides unless you use a via-in-pad. If the signal doesn’t connect the top and bottom layers, the metallic hole can create stubs(We can discuss this in the future) that cause reflections in high-speed designs.

Blind Vias connect one outer layer to one or more inner layers but do not go all the way through the board. Useful when you want to save on space and can do part mounting on the other layer that you haven’t connected to.

Buried Vias as the name suggests, is buried inside the PCB, in the inner layers, with no direct connection to the 2 outer layers. Pros: Excellent for multi-layer PCBs, no impact on the outer layers, great for high-density designs. Both Buried and Blind vias are expensive as they require multiple stacking and drilling processes.

Micro vias are a special type of via with an aspect ratio of 1:1 or less and a hole depth of less than 0.25mm, typically used for single-layer transitions. Unlike traditional cylindrical vias, micro vias have a conical structure that tapers from one layer to the next. Categorized into two types: Stacked Vias, where multiple micro vias are aligned vertically across different layers (one on top of the other), and Staggered Vias, where vias are placed on different layers but do not align directly with each other.

Always weigh the trade-offs between cost and space requirements for your next PCB design.

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Cool Tech (Literally!)

Posted under Educational, Product Design, Product Reviews, Technology on September 1st, 2024 by Amaldev

If you’ve been keeping an eye on the cooling and thermal solutions space recently, you might have noticed a significant shift in the last year. A new tech is emerging that could eventually replace traditional cooling fans, working in tandem with vapor chambers (check my previous posts for more on that) and heat pipes. The key player driving this innovation is Frore Systems, which introduced its ultra-thin (just 2.5mm high) cooling solution last year at CES. Let’s dive into the tech behind it.

From what I’ve gathered through patents and videos, this technology revolves around active piezoelectric coolers. Piezoelectric materials have a unique property: they can deform or move when an alternating voltage is applied. They ingeniously leveraged this by creating a mechanical system where many tiny piezoelectric elements move in unison to generate airflow. Essentially, it’s a piezoelectric microelectromechanical (MEMS) system.

Why is this exciting? These MEMS devices can be produced using standard IC fabrication methods, meaning they can be scaled up for mass production. In terms of specs, they can generate nearly 1700Pa of static pressure, which allows them to push air through very small spaces at high speeds on an ultra-thin profile and even through filter membranes(Which means no dust in laptops!). There are already videos out there showing how laptops and phones retrofitted with these units achieve better cooling with virtually no additional noise. It’s easy to see how this could become the new standard for cooling consumer electronics.

I’m writing about this now because just last week, a new competitor entered the market: xMEMS Labs. They’ve demonstrated a 1mm-thick chip capable of cooling, likely using similar principles. However, xMEMS appears to be leveraging MEMS speaker technology to move air directly over the chip. Imagine a speaker displacing air at ultra-high frequencies beyond the audible range – this could be connected in parallel across a surface to achieve similar cooling effects. Read up more on them. I need to stop because of character count limitations.

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