Welcome to HW Design Minute Tips Vol. 1!
In this quick post, I want to share a real-life situation that shows what can happen when vias are placed incorrectly. During our recent rapid prototyping project, we noticed on a PCB, that one of the pads on a 1210 capacitor had less solder than the other. And guess what? It turns out there were some vias chilling inside those pads!
Here's the deal: These vias were through-hole ones that weren't filled, so the soldering paste could sneak its way into the holes. As a result, there wasn't enough solder on the pad. And let me tell you, this issue gets worse when the vias are big. In our case, they had a diameter of 0.35mm. But hey, take a look at the pictures, and you'll see it for yourself.
For now, the prototypes are still working fine, but the problem is that the solder could weaken and break after a couple of months. And that's definitely not what we want, right? During prototyping, we can fix it by manually adding more solder after the reflow process. It's not a huge deal, just a bit of extra work that could've been avoided with better design steps.
I get it, sometimes you can't avoid using vias like this, especially when you have a lot of components packed tightly together. In those cases, you can try using smaller diameter vias, around 0.15 - 0.2mm, consider filling the vias, although it's not a standard priced process, or improve the stencil printing by using a thicker stencil ,if the other components can handle more paste. In the current case luckily we have plenty of space therefore we can move the vias out of the pad and next time we will get a better result.
So remember, by being careful with via placement and taking some simple precautions, you can make your designs more reliable and long-lasting. It's all about thinking ahead during the design phase to save yourself from unnecessary rework later on. Stay tuned for more HW Design Minute Tips coming your way!
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