Author Topic: Applying a Chamfer to a PCB Post Production  (Read 641 times)

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Offline Inhibit

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Applying a Chamfer to a PCB Post Production
« on: October 27, 2021, 01:00:50 pm »
I had some cheap test PCBs made up for an edge connection (cartridge port). And I'm curious how well applying a chamfer (since the board itself seems to be ideally sized) post-production will work out.

To do it I'm thinking of making a jig for one of my small grinding wheels and seeing how well it does. And dust collection because my lungs make horrible filters!

And I'll post a follow up if anyone's interested to see the results.

Anyone have experience with this? Horrible idea? Okay but not practical?
 

Offline elecman14

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Re: Applying a Chamfer to a PCB Post Production
« Reply #1 on: October 27, 2021, 01:51:21 pm »
Would be concerned about delamination due to removal and possible exposure of the copper and core. This would be especially bad if it was a more than 2 layer board. Believe the beveling process is typically done prior to adding the surface finish in most cases. Usually that area has a mechanical keep out to prevent copper removal during the process. You also did not specify surface finish or expected mating cycles but if you are using enig or hasl that has a shorter life than say hardened gold. Not sure how comfortable I would be shipping a product using this method but if it was for porotype on in house use it may be fine. If you talk to your board house they typically can do this and would be happy to separate you from your money due to it not following their standard process  ;D
 

Offline sandalcandal

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Re: Applying a Chamfer to a PCB Post Production
« Reply #2 on: October 27, 2021, 01:57:52 pm »
Haven't done it before but I'd suggest maybe a mini router table with a chamfer bit?
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Offline Inhibit

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Re: Applying a Chamfer to a PCB Post Production
« Reply #3 on: October 27, 2021, 04:28:26 pm »
Good points. In this case there's a (possibly) large enough area from the board process without hitting the fingers. With no other routing down there. This is a HASL process dual layer FR4(?) board as a prototype prior to a SMD redesign.

Although I looked at SMD versions of the memory and whooooo boy, not for those prices.

With these I'm looking at my 5 pack of prototype boards and wondering if I could design a process to easily give them a bit of a round or chamfer on the leading edge. Maybe a little easier than "apply file". And I really only need one or two reserved to think about the design with. The rest need to be dedicated to science so they won't end up in a bottomless pit of unused "stuff".

Honestly I couldn't recall having ever sanded off part of a fiberglass resin board for any reason and didn't know if I was missing something obvious that'd make it a non-starter.
 

Offline langwadt

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Re: Applying a Chamfer to a PCB Post Production
« Reply #4 on: October 27, 2021, 04:35:44 pm »
Would be concerned about delamination due to removal and possible exposure of the copper and core. This would be especially bad if it was a more than 2 layer board. Believe the beveling process is typically done prior to adding the surface finish in most cases. Usually that area has a mechanical keep out to prevent copper removal during the process. You also did not specify surface finish or expected mating cycles but if you are using enig or hasl that has a shorter life than say hardened gold. Not sure how comfortable I would be shipping a product using this method but if it was for porotype on in house use it may be fine. If you talk to your board house they typically can do this and would be happy to separate you from your money due to it not following their standard process  ;D

beveling has to be done last because to do hard gold for fingers they have to be shorted together, the trace shorting them is milled off after gold plating
 
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Offline srb1954

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Re: Applying a Chamfer to a PCB Post Production
« Reply #5 on: October 27, 2021, 09:24:19 pm »
I had some cheap test PCBs made up for an edge connection (cartridge port). And I'm curious how well applying a chamfer (since the board itself seems to be ideally sized) post-production will work out.

To do it I'm thinking of making a jig for one of my small grinding wheels and seeing how well it does. And dust collection because my lungs make horrible filters!

And I'll post a follow up if anyone's interested to see the results.

Anyone have experience with this? Horrible idea? Okay but not practical?
If these PCBs already have components on them then don't use a grinder.  Safest way would be to use a hand file (with ESD strap).

One firm I worked at had some assembled PCBs that were slightly oversized and wouldn't fit the case. The factory staff decided that the simplest solution would be to grind the PCB edges down with a grinder. The net result was that all the boards had severe ESD damage to the electronics and the PCBs had to be written off.


 

Offline thm_w

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Re: Applying a Chamfer to a PCB Post Production
« Reply #6 on: October 27, 2021, 09:53:58 pm »
If these PCBs already have components on them then don't use a grinder.  Safest way would be to use a hand file (with ESD strap).

One firm I worked at had some assembled PCBs that were slightly oversized and wouldn't fit the case. The factory staff decided that the simplest solution would be to grind the PCB edges down with a grinder. The net result was that all the boards had severe ESD damage to the electronics and the PCBs had to be written off.

Good point, although if it absolutely needed to be done you could use a carbide burr, and some carbon brushes to the shaft of the tool, to bleed off any charge to ground.

 

Offline IconicPCB

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Re: Applying a Chamfer to a PCB Post Production
« Reply #7 on: October 29, 2021, 08:12:01 am »
Many years ago there used to be a company in the states... RADOL design... they made an edge chamfering machine.
A scraping unit which would take the PCB and drive it against a scraping knife thus forming the edge profile.
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