Help with understanding some layout features

I am studying board layout using other projects to study extra topics.

So I found this board here.

It has some metal boxes over some components for shielding RF parts of the circuit.

It also has two metal areas exposed along two edges of the board. I am having a hard time understanding their needs but my guess is it is used to connect something external maybe to act as a heatsink.

Also, a second question I have is regarding the fixation holes. Is it a good practice to connect all of them on the ground or in the carrier board? Or is it better to just connect one, or none of them?

I am not sure if these are good questions for this forum, but it would be nice if someone could give me a hint on this topic or indicate another place for asking these questions.

FYI…

Once upon a time I taught EMC to our engineering staff and found this book was the best resource (at the time, 30 yrs ago). But, still very valid… Especially for designing PCB’s…

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I’d rather suppose solid connecting to metal box (may be it has springs there) being a shield for the whole PCB. And mounting holes ensuring solid connection can also suggest the same.
In one my design I have done exposed track along the pcb edge but, even it was gnd it was separated from gnd fill near it and connected to gnd fill only in one point near the USB connector (the only connector that PCB has). I was thinking several weeks how it should be done and it was the construction being the best according to my imagination about what electrons like to do. But I’m not sure if it is really the best solution. The problem I wanted to solve was credit card size plastic box of this device made of two parts with the possibility of ESD getting inside along the side edges of the housing. My idea was to take such sparks out of my element gnd connections and direct it the shortest way out of my circuit to the USB cable shield.
In case my description was no clear enough you can see its photo here:

I think there is no one and only one answer to this question.
I have plastic boxes and have all holes at PCB grounded. I don’t know if pieces of metal (screws) not connected to ground are a problem or not. Maybe a strong field can generate sparks between the screws and ground, but not if they are connected.

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Sorry but not a Kicad question

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Thanks for the comments guys.

I eventually found what those pieces of metal were doing on this particular board. Actually, the squares of metal were just “saving space” for something to sit on top or under. But they were also exposed allowing the heat to move with the thing that sits there.

There is the source link in the end but I am going to paste the images here just in case.

image

Also this one

image

Here is the source link, it has other valid links inside.
https://docs.novatel.com/OEM7/Content/Core_Installation/MountingPrintedCircuitBoard.htm

Yeah, this is not a Kicad question but it was posted in the Projects section so I was thinking that I could use this place to discuss some questions regarding the projects we are working on. But sorry if it is not a good place to do that.

Plastic can be different when it comes to the HF signal… sometimes the radio is transparent, sometimes it’s not… in general, for an HF screen, plastic is a bad option… I once took measurements with a spectrum analyzer and plastic quite strongly influenced the characteristics of the signal… but there are a lot of but … frequency? purpose ? operating conditions of the device? Is there a power supply or other sources of interference nearby? etc… if you want to be sure and there is no way to check, use an aluminum alloy…

There needs to be a KiCad related question in Project discussion, this is after all a KiCad forum :wink:

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Well, this is your problem😜, and I am using Kicad.

Using Kicad and asking your above question are mutually exclusive events.

I also believe the problem is yours, @leoheck , and am pleased to read the original question is solved so this thread can be closed because it is not Kicad related. :slightly_smiling_face:

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