Microvias PCB

16 January 2020
New

A microvias pcb is obviously smaller via PCB, but exactly how small are they? Most people consider microvias to be a via with a diameter of less than 150 µm. These tiny holes are drilled by lasers, a process that is constantly being improved. New advances in laser drilling techniques could reduce microvias down to 15 µm. The lasers involved can only drill through one layer at a time. However, HDI microvias pcb manufacturers can make through microvias by drilling them separately in multiple layers and stacking them.

Microvias PCB have a lower potential for manufacturing defects than normal vias. This is because laser drilling doesn’t leave any material behind in the drilled out holes. However, microvias PCB have the same risks as normal vias when it comes to plating and solder reflow. Thus, it’s important that you discuss tenting or filling your microvias with your manufacturer.

I need some help with my microvias PCB. I will design a 10 Layer microvias PCB with micro-vias and buried-vias. I asked my microvias PCB manufaturer for a matching microvias PCB stack-up and for the design rules.

Now I need micro-vias from the top-layer to the inner 1 layer and from the inner 8 layers to the bottom layer. That works fine, i can choose it in the microvias PCB board settings. But, I need also buried-vias from the inner 1 layer to the inner 8 layers, and there is my problem because I can’t choose it. Have you guys any suggestions how I can solve this problem?

Microvias PCB is used in conjunction with build-up layers and are generally blind or buried vias; they connect one or two (maximum) build-up layers to the copper top or bottom. If you are unable to select this option in the PCB Properties, it is likely that you do not have any build-up layers on the top/bottom of the board. Here are some general steps to follow to place micro vias:

1. Under Options > PCB Properties, check the Micro Vias box found under the Vias Support group (note: you must have build-up layers on the top or bottom of your board. You can change the number of single-layer build-ups on the left)
2. In the Allowed Vias box, select the layers between which you would like to allow micro vias (If you would like to allow micro vias between more than one layer (maximum of two), you can change the settings in the Pads/Vias tab under Maximum Layer Span. Make sure to click Apply before you return to the PCB Properties tab)
3. After you have finished selecting the allowable layers, click OK and return to your design
4. Place a via (Place > Via)
5. In the dialog that pops up, select the layers between which you would like the via place. If you select a combination of layers that was enabled in the PCB Properties, Ultiboard will automatically know that you would like to place a micro via and will configure the hole size and annular ring based on this. Now if you double-click on the via that was just placed, the heading of the properties dialog should say Micro Via Properties, which will show you that if you have configured it properly.

If you need a via that goes all the way through the board, I do not believe this fits the actual definition of micro via. You should really contact your microvias PCB board manufacturer to find out how small they are willing to go, but based on the IPC-2222 Sectional Design Standards for Rigid Organic Printed Boards, the minimum drilled hole sizes for plated-through hole vias should be at least 0.2 mm, but obviously larger as the thickness of the board increases. And then you also have to take into account the annular ring of the via.

The via-in-pad process supports more technology on fewer layers, proving that bigger is not always better. Since the late 1980’s we have seen video cameras using cartridges the size of a novel, shrink to fit in the palm of your hand. Mobile computing and working from home pushed the technology further to make computers faster and lighter, allowing the consumer to work remotely from anywhere.

HDI microvias PCB Technology is the leading reason for these transformations. Products do more, weigh less and are physically smaller. Specialty equipment, mini-components, and thinner materials have allowed for electronics to shrink in size while expanding technology, quality, and speed.