Via/poly and pad/ground question

Community PCB Design
1

I’m working on a capacitive touch PCB, and have a couple issues that I hope y’all can answer for me:

  1. I’ve installed vias to tie the sensor copper pad on Top to the Bottom layer. However, it looks like these pads have a dead zone around them, whereas I actually want the larger copper pad to be integrated with them. Is there a way to adjust the via holes, or should I be approaching this differently?

  2. Pin 12 on my connector will carry ground to the sensor board for signal shielding, but my hatched polygon ground fill is not attaching to it. I thought assigning “GND” to the pad and the poly would connect them. What have I done wrong here?

I’ve attached a .png of the board.

And kinda goes without saying: I’d love any other comments on the PCB design. I’m quite the n00b here.

Mucho Thanks,

-g

2

Oop. Using Eagle.

Thx!

3

Question #1 was solved by setting the pad and wire signal to the same value. Eagle closed the poly onto the via’s pad.

I’m still trying to figure out Q#2 : how to tie the ground poly onto that pad.

4

Attach your .sch and .brd files and I will take a look.

Also, if you have a schematic or board that you are basing your design off of, post a link to that as well.

5

I tried to attach the .brd to my original post… it won’t allow that extension :frowning: … I’ve attached it as .txt (so just rename it, to open it). There is no .sch since this is just a set of capacitive sensors.

Thanks!!

6

First, how did you make the pads? Just by the rectangle tool? I am asking because I can’t even click on the pads.

Second, Are those pads for a SMD header?

Also, that is not how you design a Ground fill.

The main reason why you are having trouble is that you do not have a schematic. A schematic in Eagle makes sure you have all the components connected and in the right locations.

My advice to you is to make a schematic, then layout your board.

7

Yup, an SMD header. I can’t use thru-hole since glass will lay directly on the Top face of the board. The pads were placed using the “SMD” tool in the part’s package.

How should the ground layer be done? The only goal of that is to protect the copper sensors on the Top layer from noise behind the board. There aren’t any parts to be grounded, and the hatching is preferred for capacitive applications.

I’m not sure what I should put on the schematic. Just a header? That doesn’t seem very useful. I guess that I could create some parts called “copper sensor pad” or somesuch.

I’ll try the schematic, and see if that makes the pads active.

Thx.

8

A friend of mine explained the issue: the pad was defined as its own net. And that net was not GND, and could not be selected/changed. Thus, Eagle was keeping the pad separate from the ground hatch-fill. Taking codlink’s and my buddy’s advice, creating a barebones schematic allowed me to attach GND to that pin/pad, and then Eagle connected it to the GND fill.

Thanks, all, and I hope this post will help others with a similar issue. It all boiled down to signals/nets, and matching them up.