Should You Use Filled Or Untreated Vias For Your PCB - Miracle Electronics

Most manufacturers are opting for the surface mount technology for building PCBs, rather than the through hole technology, so as to allocate lesser space on the board, making them smaller and easier to install. But, with the rising use of surface mount technology components, more vias are being used too. Vias are holes for electrically connecting stacked pads on different circuit layers. 

While all vias essentially perform this same function, there can be different types of vias, depending upon their appearance on the PCB surface, namely through vias, blind vias, and buried vias.

Treating the vias

In order to improve the thermal performance of the PCB, there can also be done some additional treatments on the vias, such as filling, covering, capping, plugging, or tenting. Such treatments can help eliminate several assembly issues like shorting between component pads, or wicking down of the solder through the hole of a via. It can also eliminate expensive troubleshooting and reworking.

Filling – This treatment fills a regular or encroached via with non-conductive epoxy paste. These filles vias have the solder mask stopping short of the pad by a few mils, making it a good compromise for medium-density PCBs, as the presence of the solder mask reduces the likelihood of the solder bridging between the via and neighbouring pad.

Plugging – This treatment plugs one or both ends of the via with a non-conductive epoxy paste to prevent solder flow-through or wicking during soldering. But, in order to allow the epoxy to plug the hole effectively, the diameter of the via should be limited to a maximum of 20 mils.

Tenting – This treatment covers both pads at the end of the hole with a non-conductive solder mask, effectively sealing the openings. A dry film with a 4-mil thickness is adequate for covering even large holes effectively, without breaking down much. But today, manufacturers are opting out of the traditional dry film, and choosing modern LPI solder mask instead, which is only one-tenth the thickness of dry films.

Advantages of filled vias

Filling the vias can have several advantages over untreated ones, some of the benefits being high routing density, better conductivity (both thermal and electrical), and EMI reduction. Being very small in size, micro-vias allow high routing density on the PCB, allowing substantial reduction in the overall PCB size, and lowering the number of layers. All of this ultimately reduces the cost of the PCB. With a smaller size, there is also reduction in the distance between the components, which in turn reduces the overall resistance of the tracks, resulting in better electrical conductivity. This high conductivity in turn helps to lower the EMI reduction. Hence, filled micro-vias are particularly helpful for conducting a large amount of heat away from a hot component. The metallic nature of the filling wicks heat naturally away from the chip to the other side of the board for further dissipation by a heat sink.

If you want to take advantage of such filled micro-vias, you can always get in touch with Miracle Electronics to get your preferred customized PCB assembly from India. Get in touch and explain all your requirements and purposes, and you’ll get the most apt PCB assembly for your application, reliable and safe.