Plated Through Slot With Signal

On 28/08/2016 4:35 a.m., Dave Wills wrote:

Hi,

 

I've been scratching my head on how to do this.  I've created a library

part which has a slot required for the device (a connector).  I'd like to

connect the slot to GND which is the shield of the connector.

 

I've tried 3 times to create gerbers that the fab company can build to, but

no success so far.

 

The Eagle library has through hole pads and SMD pads.  Through hole pads

will connect to inner layers appropriatly and of course SMD pads won't.  I

don't see a way to create a slot that is also a pad so that it connects

internal layers.

 

My last attempt was to put the plated slot on top of a through hole pad.

But the fab company skipped the slot, just doing the through hole pad.

 

Any suggestions on how I might do this?  I'm looking for a solution that

can't be misinterpretted so I can use it on multiple boards without

worrying about the fab house.

 

Thanks!

 

Dave

 

Hi Dave

PCB CAD and the manufacturing process are separate worlds that you need

to bring together. There are considerations on both sides and you need

to understand the process on both sides. The fab house often has

guidance on their web site of what they require. It pays to understand

how PCBs are manufactured, then you would have realised for yourself

what I say below.

As for your slot.

Because you want it plated (THP), there must be copper on both sides of

the board at that point. This a basic board house stipulated rule.

Because its a slot you need to define it on a milling layer.

Commonly, milling by default is one of the last steps as that action

cuts out the board and chops out any openings/millings in the board, the

ones you don't need THP.

Milling that must be plated is an additional layer and occurs earlier

when the top to bottom drills are done, before both are thru hole plated.

So for a plated slot you will need to provide a Gerber of the layer

defining the slot and additionally make the fab house aware of it.

HTH

Warren

warrenbrayshaw wrote on Sat, 27 August 2016 18:26

On 28/08/2016 4:35 a.m., Dave Wills wrote:

Hi,

 

I've been scratching my head on how to do this.  I've created a

library

part which has a slot required for the device (a connector).  I'd

like to

connect the slot to GND which is the shield of the connector.

 

I've tried 3 times to create gerbers that the fab company can

build to, but

no success so far.

 

The Eagle library has through hole pads and SMD pads.  Through

hole pads

will connect to inner layers appropriatly and of course SMD pads

won't.  I

don't see a way to create a slot that is also a pad so that it

connects

internal layers.

 

My last attempt was to put the plated slot on top of a through

hole pad.

But the fab company skipped the slot, just doing the through hole

pad.

 

Any suggestions on how I might do this?  I'm looking for a

solution that

can't be misinterpretted so I can use it on multiple boards

without

worrying about the fab house.

 

Thanks!

 

Dave

 

 

Hi Dave

PCB CAD and the manufacturing process are separate worlds that you need

 

to bring together. There are considerations on both sides and you need

 

to understand the process on both sides. The fab house often has

guidance on their web site of what they require. It pays to understand

 

how PCBs are manufactured, then you would have realised for yourself

what I say below.

 

As for your slot.

Because you want it plated (THP), there must be copper on both sides of

 

the board at that point. This a basic board house stipulated rule.

 

Because its a slot you need to define it on a milling layer.

 

Commonly, milling by default is one of the last steps as that action

cuts out the board and chops out any openings/millings in the board,

the

ones you don't need THP.

 

Milling that must be plated is an additional layer and occurs earlier

when the top to bottom drills are done, before both are thru hole

plated.

 

So for a plated slot you will need to provide a Gerber of the layer

defining the slot and additionally make the fab house aware of it.

 

HTH

Warren

Hi Warren,

Thanks (again) for the reply.

Yes, bringing together the CAD and fab worlds is what I've been trying to

do.

There is copper on both sides of the board.  It is there with a through

hole pad.  The pad overlaps the slot.  The pad is supposed to be connected

to an inner layer ground plane, but as yet it is not.

The existence of both a through hole pad and the overlapping slot confused

the fab house, so they omitted the slot.  I'm trying to make it foolproof

so I don't need to worry about who the fab house is.

The slot is defined in a separate slot file.  It is quite clear and is also

shown in the fab house internal gerber views.

The order for the boards gave me an option for plated or unplated slots.  I

chose unplated for the proto run.  But they still missed the slots.

I'm going to take a look at making the slot with overlapping through hole

pads in the library.  I don't know if the fab house would not interpret

that correctly either.  Here's a picture of the current design:

Thanks,

Dave

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Attachments:

I have a few thoughts

If the service you are using is does not entitle one to plated slots, that

would be a reason for them not producing a plated slot.

If you specifically asked for the plated slot and they did not provide it,

they should make a new board for free.

If there is contention in the files you provided to the board house they

should alert you before proceding. As they did not you should consider

changing your board house.

Endeavour to have your the slot width match one of their standard milling

tool widths.

You could maually remove the drill hole from the drill file. But that's a

step you may forget to do some times.

HTH

Warren.

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Web access to CadSoft support forums at www.eaglecentral.ca.  Where the CadSoft EAGLE community meets.

On 08/28/2016 03:17 PM, Dave Wills wrote:

I

chose unplated for the proto run.  But they still missed the slots.

I am not an expert on pcb manufacturing but it seems that slots can be

cut before or after plating or both before and after plating.

With before and after is an extra step so it would cost more. I also

suspect that some board houses cut the slots last when they depanelize

so a plated slot may be more.

Paul R.

warrenbrayshaw wrote on Sun, 28 August 2016 17:44

I have a few thoughts

 

If the service you are using is does not entitle one to plated slots,

that would be a reason for them not producing a plated slot.

If you specifically asked for the plated slot and they did not provide

it, they should make a new board for free.

If there is contention in the files you provided to the board house

they should alert you before proceding. As they did not you should

consider changing your board house.

 

Endeavour to have your the slot width match one of their standard

milling tool widths.

You could maually remove the drill hole from the drill file. But that's

a step you may forget to do some times.

 

HTH

Warren.

Hi Warren,

The fab house I'm using does do plated through slots.

They have offered to remake the board for free.  But since I only did

prototypes, it was much faster for me to have a machine shop drill the

slots for now.  I'm just trying to insure when I do a much larger run that

I don't have problems.

Yes, they should have alerted me of contention.  They admit they dropped

the ball, part of them agreeing to remade the boards.  I won't try another

fab house yet.

I think my best option at this point is to delete the through hole entirely

and go to SMD pads with a slot.  If I really do need to connect the slot to

ground (which I don't believe I do), then I can do it post-routing.

Thanks again for the help.  BTW, just where in the U.K. are you located?

Dave

--

Web access to CadSoft support forums at www.eaglecentral.ca.  Where the CadSoft EAGLE community meets.

warrenbrayshaw wrote on Sun, 28 August 2016 17:44

I have a few thoughts

 

If the service you are using is does not entitle one to plated slots,

that would be a reason for them not producing a plated slot.

If you specifically asked for the plated slot and they did not provide

it, they should make a new board for free.

If there is contention in the files you provided to the board house

they should alert you before proceding. As they did not you should

consider changing your board house.

 

Endeavour to have your the slot width match one of their standard

milling tool widths.

You could maually remove the drill hole from the drill file. But that's

a step you may forget to do some times.

 

HTH

Warren.

Hi Warren,

The fab house I'm using does do plated through slots.

They have offered to remake the board for free.  But since I only did

prototypes, it was much faster for me to have a machine shop drill the

slots for now.  I'm just trying to insure when I do a much larger run that

I don't have problems.

Yes, they should have alerted me of contention.  They admit they dropped

the ball, part of them agreeing to remade the boards.  I won't try another

fab house yet.

I think my best option at this point is to delete the through hole entirely

and go to SMD pads with a slot.  If I really do need to connect the slot to

ground (which I don't believe I do), then I can do it post-routing.

Thanks again for the help.  BTW, just where in the U.K. are you located?

Dave

--

Web access to CadSoft support forums at www.eaglecentral.ca.  Where the CadSoft EAGLE community meets.