JLCPCB Bonus holes

[phil from seattle]

So, I got my latest assembly order amazingly fast - 6 days from order placed to boards in hand.  All the components look properly placed with no tombstones or placement errors.  but...

Each board has 2 extra holes that aren't in the gerbers I sent, don't show up in their gerber viewer but are definitely on the board.  They look innocuous.   But what if they put them some where that breaks a trace or some such. See the pix. First is their gerber viewer, 2nd is a full board shot (bonus holes in upper left and lower right) and 3rd is a microscope shot of the upper left one. They don't appear to be plated through but you can see that copper pour is recessed from the hole so it was in some gerber they used. What is strange, this is a reorder and I sent the exact same gerbers as before - those boards came out perfect. I have a message into them. After the rotated pads issue and now this, I'm a little uncertain about using them for more boards.

[edit] ugh. just realized I put it in the wrong subforum. meant to put it in manufacturing. Sorry 'bout that. Maybe some kind admin could move it?

[TimNJ]

Since you ordered assembly service, presumably they added tooling holes to the PCB to help facilitate some assembly step(s). It's a bit unusual because (usually) these holes are placed on the side-rails of the PCB panel, not on the actual design. But for prototype assembly, unless the size of your board is large or you order a lot of them, you don't get your own panel, so they need to treat each board individually during assembly.

Ed: I should note that they could have added side rails to your design, and still put your design in a shared panel...but maybe they've decided that those rails are just wasted space on the panel, and would rather put the holes on your design. Par for the course, I guess.

[Mecanix]

Tempting to sell that microscope I just got and have the fab house do the bulk work :/ Looks good!


 

[phil from seattle]

Since you ordered assembly service, presumably they added tooling holes to the PCB to help facilitate some assembly step(s). It's a bit unusual because (usually) these holes are placed on the side-rails of the PCB panel, not on the actual design. But for prototype assembly, unless the size of your board is large or you order a lot of them, you don't get your own panel, so they need to treat each board individually during assembly.

Ed: I should note that they could have added side rails to your design, and still put your design in a shared panel...but maybe they've decided that those rails are just wasted space on the panel, and would rather put the holes on your design. Par for the course, I guess.

Well, maybe.  But I think not - it changes my ground plane, they didn't do it to the exact same gerbers in the previous order and it doesn't show up in their gerber viewer. Also, those holes are so small (look like 30 mil or so).  I ordered 30 btw.

[Mecanix]

You probably received the hole that I've offset by half-and inch in my last less-than-experienced layout! Failed to notice and forgot to remove it from the Drill NC file before sending it over My PCB must have been a side job to yours on that large FR-4 panel. Can't think of anything else... (sh*t happen, sorry!)

[phil from seattle]

Tempting to sell that microscope I just got and have the fab house do the bulk work :/ Looks good!

Oh, you will need the scope no matter who does your assembly.  But, I am definitely of the opinion that it's a good deal as long as they don't change the board electrically from what I intended.

[Mecanix]

Just noticed/realized you've ordered 30x, so can't be the errant hole I've stupidly offset (I'm out of trouble!). Got to be that Drill Devil then. Not cool...
See if they are keen on giving you sort of a 'financial' break on the next batch.

[CoteRotie]

If I recall correctly there's a well hidden page on the JLCPCB site that tells you that you have to add 2 tooling holes to your board if you want them to do SMT assembly.  If you don't add the holes they will.  I think they're pretty careful to put them somewhere where they won't impact a trace or a plane (much).

EDIT- From the website: https://support.jlcpcb.com/article/92-how-to-add-tooling-holes-for-smt-assembly-order
How to add tooling holes for SMT assembly order
When adding tooling holes, please keep the following in mind:

1. Two or three tooling holes should be added on the PCB, they should be placed in opposite corners of the PCB and as far apart from one another as practical.
2. Tooling holes should be 1.152mm(45.4mil) round non-plated holes with 0.148mm solder mask expansion.
3. Tooling holes are only required for SMT assembly orders.
4. Please try to add tooling holes on empty space and keep them away from traces. If there is no enough room, you can add them to the copper area.

[Mecanix]

Good find, CoteRotie.
Man quite a lot of stuff to learn from those fab houses in a day... glad you've put up this thread, Phil.

[phil from seattle]

wow.  I never saw that before and I've had 5 boards assembled by them.  This is the first time they added the holes. thanks.

[edit] well hidden it sure is.  there is nothing in their "How to order" https://support.jlcpcb.com/article/68-instructions-for-ordering about tooling holes other than "if you need tooling holes".  Makes it sound like it's optional.

[TimNJ]

Since you ordered assembly service, presumably they added tooling holes to the PCB to help facilitate some assembly step(s). It's a bit unusual because (usually) these holes are placed on the side-rails of the PCB panel, not on the actual design. But for prototype assembly, unless the size of your board is large or you order a lot of them, you don't get your own panel, so they need to treat each board individually during assembly.

Ed: I should note that they could have added side rails to your design, and still put your design in a shared panel...but maybe they've decided that those rails are just wasted space on the panel, and would rather put the holes on your design. Par for the course, I guess.

Well, maybe.  But I think not - it changes my ground plane, they didn't do it to the exact same gerbers in the previous order and it doesn't show up in their gerber viewer. Also, those holes are so small (look like 30 mil or so).  I ordered 30 btw.

You “think not” what? Unless this is a very high performance analog or high speed digital design, I don’t see how those holes will have any impact on electrical performance. I agree I’d prefer for them to ask you your opinion first before choosing the hole location.

[phil from seattle]

Do you want some fab changing your board?  Yes, I agree this change is innocuous but I designed it a specific way and don't want them making decisions about it.  I don't think that's at all unreasonable a position.

[Mecanix]

None of my business how they do what they do, I'm literally clueless and learning along, but why aren't they not fixturing/tooling up and using customer's mounting hole(s) as opposed to modifying the layouts is rather hard to understand. Looks like there's been quite a significant amount of work in Phil's design. Last thing I'd want are my design randomly holed up 

Not much of any issue for that $10 qfn breakout test pcb with a few leds. Not entirely sure how I'd like that for a larger project... I'd probably put 5 attorneys and 2 prosecutors on the case and cry out my hard-to-fit little usb connector lol

[nuclearcat]

As nice gesture they can add automatic detection of missing tooling holes and red warning about that...

[CoteRotie]

This is the first time they added the holes. thanks.

I think maybe if they find holes that are close enough to what they need they don't have to add them.  If there aren't any that meet the parameters then they do.  That's my current working theory anyway....

[phil from seattle]

This is the first time they added the holes. thanks.

I think maybe if they find holes that are close enough to what they need they don't have to add them.  If there aren't any that meet the parameters then they do.  That's my current working theory anyway....

Not a bad theory except this is a repeat order and for the first one (with the exact same gerbers) they didn't add the holes.

[CoteRotie]

This is the first time they added the holes. thanks.

I think maybe if they find holes that are close enough to what they need they don't have to add them.  If there aren't any that meet the parameters then they do.  That's my current working theory anyway....

Not a bad theory except this is a repeat order and for the first one (with the exact same gerbers) they didn't add the holes.

Or it's just totally random and depends on whichever person is running the process that day 

[phil from seattle]

Yeah  I'm thinking that's exactly it.

[bson]

It might have made more sense to put the tooling holes under TH parts.