[SOLVED] What are the dot metal around screwholes on a motherboard? Do I need my screws to touch those metal dots ?

[Iamcid]

Hi,

I'm currently assembling a motherboard in a case and I've noticed it's screws don't touch the little dot metal around the screw holes. Does the screws need to touch those little dot metals ? What are they? Thank you in advance

 

[kanewolf]

Hi,

I'm currently assembling a motherboard in a case and I've noticed it's screws don't touch the little dot metal around the screw holes. Does the screws need to touch those little dot metals ? What are they? Thank you in advance

Those are ground points. The standoff screws should touch them. Double check thst you are using the correct screws.

 

[critofur]

The little dots are solder.

If you don't over tighten the screws, you'll be fine - if you have other, slightly wider screws that do touch the solder bits then the force of the screw is spread over a wider area thus less possibility of damage to the PCB.

Do the smaller screws that you're using have the correct threads? I've seen both types of threads (the two common threads used w/PCs - one being the finer threads which go into places like the sides of optical internal drives, and the coarser threads which you might call "case threads") used on stand offs, but it's usually the coarser ones which are the same type that screw into the backs of power supplies.

Even if the screws don't make contact w/the metal bits, the standoff on the bottom might be, in case you're worried about grounding - but, multiple ground wires coming from your power supply do reach the motherboard regardless.

 

[Iamcid]

The little dots are solder.

If you don't over tighten the screws, you'll be fine - if you have other, slightly wider screws that do touch the solder bits then the force of the screw is spread over a wider area thus less possibility of damage to the PCB.

Do the smaller screws that you're using have the correct threads? I've seen both types of threads (the two common threads used w/PCs - one being the finer threads which go into places like the sides of optical internal drives, and the coarser threads which you might call "case threads") used on stand offs, but it's usually the coarser ones which are the same type that screw into the backs of power supplies.

Even if the screws don't make contact w/the metal bits, the standoff on the bottom might be, in case you're worried about grounding - but, multiple ground wires coming from your power supply do reach the motherboard regardless.

So I should be fine if I'm using smaller screws that don't touch those tiny metal dots? I presume as you said that the standoffs touching the mobo from the back should be enough for grounding, but I'm no expert. That's why I'm asking you guys.

 

[drea.drechsler]

So I should be fine if I'm using smaller screws that don't touch those tiny metal dots? I presume as you said that the standoffs touching the mobo from the back should be enough for grounding, but I'm no expert. That's why I'm asking you guys.

Those dots are connected to the board's ground plane(s). It's a very good idea that the screws contact at least one of those dots to prevent ground loops that can present odd, often intermittent, problems. It also suggests the screw heads are too small which can lead to crushing the fibers of the board if tightened too hard.

I'd suggest putting a washer under the screw head and that should avoid any of those problems. Either that or look through the hardware kit for your case to find a the correct screw, possibly one with a hex head and flattened on the mating side, kind of like a washer that's pre-installed. You could be using a screw that's meant to be used for mounting drives or something similar.

 

[geofelt]

Can you post a pic of your issue?
Parts should fit without needing other measures.
Consider that you are doing something wrong.

Check your case parts and test fit a screw into a motherboard standoff.
Many screws look similar.
The motherboard should fit the rear i/o plate cleanly and all motherboard mounting holes should match up to the case mounting posts.

 

[Iamcid]

Can you post a pic of your issue?
Parts should fit without needing other measures.
Consider that you are doing something wrong.

Check your case parts and test fit a screw into a motherboard standoff.
Many screws look similar.
The motherboard should fit the rear i/o plate cleanly and all motherboard mounting holes should match up to the case mounting posts.

https://imgur.com/4OsA7I1

It kinda looks like this, the screw are not touching the tiny metal dots. But the screws are supposedly for MOBOS. Should I go out to buy hex head insteads in hope that they reach the tiny dots ? On the back of the mobo I can't take a picture.

 

[geofelt]

If these are the screws supplied by the case,
I think you are ok if you want to do nothing.
The hidden part is probably doing the grounding sufficiently well.

 

[Iamcid]

If these are the screws supplied by the case,
I think you are ok if you want to do nothing.
The hidden part is probably doing the grounding sufficiently well.

Well they are not, but they fit perfectly. My only concern is that they don't reach the metalic dots on the MOBO. On the back I presume they do. It's a B550 gaming X v2 Gigabyte.

 

[Karadjgne]

Those solder points aren't used for ground purposes but heat purposes. All of the components on the motherboard, especially any transistors, mosfets etc, will dump heat into the ground plane. The ground plane on the motherboard is designed to handle all that heat independently of other avenues. The solder points just add extension from the ground plane to the motherboard tray if you use metal screws and they touch. But it's not required. Most motherboard screws actually come 0.5mm - 1mm longer than standard and use a paper gasket, just to avoid the ground loops and RFI interference and noise, as mentioned by @drea.drechsler. The motherboard itself only requires grounding through the black wires in the 24pin psu connector.

 

[Iamcid]

Those solder points aren't used for ground purposes but heat purposes. All of the components on the motherboard, especially any transistors, mosfets etc, will dump heat into the ground plane. The ground plane on the motherboard is designed to handle all that heat independently of other avenues. The solder points just add extension from the ground plane to the motherboard tray if you use metal screws and they touch. But it's not required. Most motherboard screws actually come 0.5mm - 1mm longer than standard and use a paper gasket, just to avoid the ground loops and RFI interference and noise, as mentioned by @drea.drechsler. The motherboard itself only requires grounding through the black wires in the 24pin psu connector.

Thank you. You understood my concern perfectly. Yes, I was afraid that I need grounding from those tiny metals around the screw holes. Mines are not touching because they are not from my case. MOBOs screw holes can come in various forms. I have another one here that doesn't have dots, but instead it has this form which will literally touch any type of screw:

https://imgur.com/2KbO1RP

 

[drea.drechsler]

Those solder points aren't used for ground purposes but heat purposes. All of the components on the motherboard, especially any transistors, mosfets etc, will dump heat into the ground plane. The ground plane on the motherboard is designed to handle all that heat independently of other avenues. The solder points just add extension from the ground plane to the motherboard tray if you use metal screws and they touch. But it's not required. Most motherboard screws actually come 0.5mm - 1mm longer than standard and use a paper gasket, just to avoid the ground loops and RFI interference and noise, as mentioned by @drea.drechsler. The motherboard itself only requires grounding through the black wires in the 24pin psu connector.

Have to disagree...I've put an ohmeter on the dots and have confirmed they are connected to the ground plane on my board. It's very dumb design to put them so close to an attachment point if it's not the intended purpose: to make solid ground connection to they case.

As an engineer who's worked on high frequency RF circuits I can tell you with a practiced certainty that a circuit board can almost never have too many ground points.

I've never seen a fiber gasket in any case hardware kit. I have seen them (usually plastic, actually) in some heatsinks to prevent shorting a screw or backplate to a motherboard trace.

 

[Iamcid]

Have to disagree...I've put an ohmeter on the dots and have confirmed they are connected to the ground plane on my board. It's very dumb design to put them so close to an attachment point if it's not the intended purpose: to make solid ground connection to they case.

As an engineer who's worked on high frequency RF circuits I can tell you with a practiced certainty that a circuit board can almost never have too many ground points.

I've never seen a fiber gasket in any case hardware kit. I have seen them (usually plastic, actually) in some heatsinks to prevent shorting a screw or backplate to a motherboard trace.

So, I should look for hex headed screws and try to reach those metalic dots ?

 

[drea.drechsler]

So, I should look for hex headed screws and try to reach those metalic dots ?

I would look for the correct screws. But if you're not experiencing any problems you might also take the redneck approach: "if it ain't broke, don't fix it". Secure grounding through the attach points is more a security policy against potential random problems and not going to be hazardous to either yourself or the hardware if missing.

 

[Iamcid]

I would look for the correct screws. But if you're not experiencing any problems you might also take the redneck approach: "if it ain't broke, don't fix it". Secure grounding through the attach points is more a security policy against potential random problems and not going to be hazardous to either yourself or the hardware if missing.

Well it's up and running for 2 years and no issues whatsoever. Correct screws means the ones that actually touch those small metal dots ? and also how dangerous can it be for the hardware itself if I leave them like this from your experience ?

 

[Karadjgne]

@drea.drechsler
Motherboards used to come with plastic clips, some still do. When you have metal to metal contact between the ground plane and solder tips and a brass screw and a metal motherboard tray, the obvious connection is going to be a ground, but that's not its primary purpose. It's purpose is a leech field to help drain off motherboard heat from the components.

The motherboard itself doesn't need either a screw attached ground, nor a thermal sink, it works perfectly fine without either, just sitting on a cardboard box, they are just added bonuses.
https://www.walmart.com/ip/M3-Compu...ashers-Set-Security-Screws-20-Pack/1383287217

The motherboard may or may not have solder dimples on the back side, some do, some don't, some replacement or even OEM kits come with washers, some don't. Doesn't hurt either way, with or without. Some cases have upto 5 plastic alignment pins, only 4x screws in the corners to hold the motherboard, to a plastic tray. But thats usually low powered, low end, uber cheap prebuilts.

Point is, regardless of original intention or design, it doesn't mean that it can't be also used for other purposes. So yes, the screw holes can act as a ground, but they are not required to do so.

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Most higher end mobo's use large amounts of power, between the VRM's and other chipsets like the super i/o, pch, Sata etc, they dump a lot of heat into the ground plane. It only makes sense to leech that extra heat as much as possible out of the board. So higher end units will generally not use washers, opting instead to use larger solder points, metal screws in direct contact to the motherboard tray and frame. It just also happens to be a ground path.

 

[Iamcid]

@Karadjgne , I presume having a motherboard with screw holes looking like this won't hurt the system also right? This system is 10 years old and had no issue with it's screw holes looking like this.

https://imgur.com/a/b2sQG5K

View: https://imgur.com/a/b2sQG5K

 

[Karadjgne]

The solder points can be as torn up and raggedy looking as they can be and all is good. As long as they don't spread outwards to adjacent points or components or the voltage planes.

It's like having a car with a bunch of dents, does nothing to affect its performance or drivability, unless the dents affect how the wheels travel etc.

 

[Iamcid]

Thank you very much. I've learned new things today. Very informative. Thank you.