Problems with Annular Rings / Restrings

[chipdesk]

I've configured the "Annular Rings" or "Restrings" in Eagle as follows:

So I expect to get Annular Rings of minimally 0.125mm wide. The DRC Check doesn't generate errors, so everything seems fine.

Unfortunately, my board manufacturer Eurocircuits complains when I insert the Gerber files for analysis:

I wonder how Eurocircuits can detect Annular Rings of 0.075mm?

Note: OAR is abbreviation used by Eurocircuits for "Outer Annular Ring".

I also notice that Eurocircuits doesn't mark all the via's as wrong, only some. There are three possibilities:

- I made a mistake

- Eagle has a bug

- Eurocircuits analysis software has a bug

What do you think?

[rachaelATWH4]

Hi Kristof,

I came across this a little while ago. After discussions with Eurocircuits I think it turned out to be that they are taking the EAGLE drill size to be the finished hole size therefore using a larger drill than the drill size specified in EAGLE so after plating it will match the specification, which therefore reduces the OAR.

Best Regards,

Rachael

[chipdesk]

Hi Rachael,

Thank you for your response. Before I even started routing in Eagle, I contacted Eurocircuits and sent them the following figure:

Eurocircuits confirmed that the figure was correct. So I have designed my board with drill holes of 0.25mm and annular rings of 0.125mm, which results in a total via diameter of:

0.25 + ( 2 * 0.125 ) = 0.50 mm

As you stated correctly, the drill holes effectively shrink from 0.25mm to 0.15mm during metallization. This process actually enlarges my annular rings from 0.125mm to 0.175mm.

But I am certainly not relying on this "annular ring enlargement". In fact, I make sure that my annular rings meet the minimum requirements of 0.125mm before the metallization process starts.

Despite my careful analysis and despite getting approval from Eurocircuits that the figure above is correct, the Eurocircuits analysis software still insists that my annular rings are too small ...

Their software claims my annular rings are only 0.075mm, where in fact I have clearly defined them to be 0.125mm in Eagle. What should I do?

[aa4649]

It seems to be a manufacturing company that designates a finished dimension of 0.25 mm. I think it is a little unusual.

As pointed out, we would like to design a hole of 0.25 mm / 0.5 mm in diameter, but the manufacturer seems to guarantee a finished hole of 0.25 mm with a tool of 0.35 mm / 0.5 mm diameter. Indeed it seems to be difficult to make (I think that 0.2 mm hole / 0.5 mm diameter is good, if you can make it anywhere in the world, specify 0.3 mm hole / 0.6 mm diameter)

So how about if you designate this to the manufacturing company.
"0.25 mm of the drill list uses 0.5 mm diameter, 0.25 mm tool, not specifying the finished hole diameter (=about 0.15 mm is good)"

Of course you can edit the gerber data and edit the drill list as small as 0.1 mm each, but such a manufacturing company is not common.

[rachaelATWH4]

---

@chipdesk wrote:

Despite my careful analysis and despite getting approval from Eurocircuits that the figure above is correct, the Eurocircuits analysis software still insists that my annular rings are too small ...

Their software claims my annular rings are only 0.075mm, where in fact I have clearly defined them to be 0.125mm in Eagle. What should I do?

---

What have you set your drill size to be? This is their finished hole size so you should set your drill size to 0.15mm so that when they drill it they use a 0.25mm drill. The problem is I am not sure what their minimum drill size is, if you are right on the edge of their capabilities it might be tricky to get something that works. I ran into this issue and had to find another manufacturer who were able to do laser drilling so I could get my design to work.

Best Regards,

Rachael

[chipdesk]

Hi Rachael,

Thank you for replying 🙂

I just checked my .dri file (which is in the gerber folder that Eagle created).

This is how it looks like:

Generated by EAGLE CAM Processor 8.3.2

Drill Station Info File: C:/Users/Kristof/Dropbox/Charger/charger_AN/charger.dri

 Date              : 23/09/2017 15:35
 Drills            : generated
 Device            : Excellon drill station, coordinate format 2.5 inch

Parameter settings:

 Tolerance Drill + :  2.50 %
 Tolerance Drill - :  2.50 %
 Rotate            : no
 Mirror            : no
 Optimize          : yes
 Auto fit          : yes
 OffsetX           : 0inch
 OffsetY           : 0inch
 Layers            : Drills Holes

Drill File Info:

 Data Mode         : Absolute
 Units             : 1/100000 Inch

Drills used:

 Code  Size       used

 T01   0.0098inch   859
 T02   0.0197inch    40
 T03   0.0217inch   196
 T04   0.0236inch     3
 T05   0.0394inch     7
 T06   0.0787inch     8

Total number of drills: 1113

Plotfiles:

 C:/Users/Kristof/Dropbox/Charger/charger_AN/charger.drd

Note that this .dri file specifies the drill diameters used. The smallest drill is for my vias:

0.0098 inch = 0.24892 mm

So that drill is 0.25 mm. At least, that's what you get if you round the number a bit. Anyway, this file tells Eurocircuits: "hey, this guy wants us to use a drill with diameter 0.25 mm for his vias". At least, that's what I hoped.

But you're saying that Eurocircuits interprets this as "hey, this guy wants to get vias with a finished hole diameter of 0.25 mm, so let's use a 0.35 mm drill to make his vias". Correct?

If that is the source of the mistake, I should perhaps change that line in the .dri file. I'm going to try that now. Hopefully it will work 🙂

[rachaelATWH4 · Accepted solution]

---

@chipdesk wrote:

But you're saying that Eurocircuits interprets this as "hey, this guy wants to get vias with a finished hole diameter of 0.25 mm, so let's use a 0.35 mm drill to make his vias". Correct? 

---

Yes this is correct.

---

@chipdesk wrote:

If that is the source of the mistake, I should perhaps change that line in the .dri file. I'm going to try that now. Hopefully it will work 🙂

---

I'm not sure... this might not work... It might be worth a try but I think you'd be better to change the drill diameters for the vias in EAGLE, making sure to set the restring such that your annular ring stays the same size as it is now (i.e take 0.1mm off your drill and add 0.1mm to the annular ring setting). Then either regenerate your Gerber files or just upload the .brd file directly (Eurocircuits takes these as a preferred option, not sure if you need to export as v7.7 for it to work, I haven't tried a v8 format file with them yet).

I hope you get this working. I'm not going to be online for the next week so unfortunately won't be able to help you any further, but I think you probably have a handle on what the issue is and will be able to fix it now anyway. Good luck!

Best Regards,

Rachael

[chipdesk]

Hi Rachael,

You're recommendation to make changes in Eagle worked:

---

    "Take 0.1mm off your drill and add 0.1mm to the annular ring setting"

---

Well, actually, I had to add 0.05mm to the annular ring which results in an increase of 0.1mm of its diameter. But I know that's what you meant. And it works perfectly now!

Thank you once again for helping me.

Kind greetings,

Kristof