PCB prototype supplier meeting nRF52840 via-in-pad requirements

[Beat]

Hi folks,

I'm trying to find a pcb prototype manufacturer which supports the via-in-pad requirements for the nRF52840 package (i.e. 0.15mm hole size with 0.1mm annular ring). However, most pcb protottype suppliers demand either minimum 0.2mm hole size and/or minimum 0.15mm annular ring.

The only supplier I found is www.multi-cb.de from Germany. They seem trustful. The only downside: Their offer has a very long manufacturing time (6 weeks), if a fixed layer stack for 50Ohm RF traces is required.

Does anybody know a good PCB supplier, capable of fullfilling the nRF52840 via-in-pad requirements and having not too long lead times?

Thanks for your hints!

[AmbystomaLabs]

There are many, many pcb manufacturers capable of doing via in pad.  I think your issue is that you are searching the wrong way.  Almost none of the via in pad is done with traditional drilling techniques.  A 3 mil drill is just too small and breaks easily.

You need to look for manufacturers with laser drilling equipment.  Via in pad is normally done with laser drilled via and then you complement the board with traditional drilled vias. Via in pad is a 20 year old technique and is manufactured worldwide.

[AmbystomaLabs]

Again, you just need to google HDI, laser drilled, microvia, etc.  There are at least a hundred manufacturers out there.

This is Sierra Circuits capabilities.  I have never used them so can't give a personal reference.

https://www.protoexpress.com/content/capability.jsp

Here's some company called ESI touting their pretty CO2 lasers.

https://www.esi.com/solutions/pcb-processing/high-density-interconnect/

[Beat]

Thanks for your hint about HDI and microvias...

However, it seems that it's not as simple as that:

Würth clearly offers HDI capabilities, but they stated by Email, that they cannot do this small size of via-in-pad.

On the other hand Eurocircuits will do the job, but they do not mention HDI nor microvias on their website.

However, I found a few suppliers who can do it (see my summary in my reply to Simon, above).

Thanks for all your support, guys.

[Radio]

Hi Beat,

I am trying to fabricate a PCB/PCBA for the first time and looking for a recommended manufacture. I am not planning to do any production level manufacturing. Just for prototyping.

I would like to know your experience with Eurocircuits if I am going to design a PCB based on nRF52840. Or any other manufacture you have tried with?

Do they also do PCBA?

How about the cost (e.g. a PCB with dimension 4cm x 4 cm)?

Thanks a lot.

[Beat]

We usually use Eurocircuits or Multi-CB for prototype manufacturing. Often Multi-CB is cheaper.

However, for the nRF52840 we used Eurocircuits, because they were able to produce via-in-pad. This feature is only required if you are going to use any GPIO on the inner pad row. If you stick to the outer pad row, then you may use any other PCB manufacturer.

If you wanna use the inner pad row for GPIOs and thus via-in-pads, then ask for a quote with special via requirements. In your Gerber data you should add a mechanical layer which marks the special via-in-pads.

And yes, Eurocircuits does PCBA, but we never used this service. So I haven't got experience here with Eurocircuits.

Hope, I could help.

[Radio]

Hi Beat,

Many thanks for the reply. My design is something similar to a nRF52840 dongle. Its a small design. I am not going to have GPIO on the inner pad row. Will using other Via types affects my performance? 

Thanks a lot!

[Beat]

No, to my knowledge no performance issue at all.

You just have only 26 GPIOs to use instead of 48. Should be no problem for a small design.

[Simonr]

Hi

I just wanted to confirm that Beat is absolutely correct. Using these other vias should not cause any performance issues.

Best regards,

Simon

[Radio]

Hi Beat/Simonr,

Thanks for the information. One quick question.

When you mentioned via-in-pad, did you also mean, ground vias which is just underneath the  aQFN73 package pad?

Thanks!

[Beat]

Oh no. The center pad ground vias are a must !  It's only about via-in-pad in the pad ring.

Ah, and check also this document: http://infocenter.nordicsemi.com/pdf/nan_040.pdf