nRF52840 Module PCB Manufacturing

[Radio]

Hi All,

I am in the process of fabricating my own PCB for the first time using nRF52840 chip. 

The design will be somewhat similar to the nRF52840 Dongle design with slight modifications.

My plan is to fabricate using the manufacture PCBWay (https://www.pcbway.com/HighQualityOrderOnline.aspx).

I want to try to get a similar quality as the nRF52840 Dongle boards. However, there are certain things I am quite not sure about.

1. What type of FR4 material is best to use?  (Options I have are: Tg140 FR-4/ Tg150 FR-4/ Tg170 FR-4/ Tg150 FR-4(Halogen-free)/ Tg170 FR-4(Halogen-free). 

2. Any idea what is the material used in nRF52840 Dongle design?

3. Should I use Via in pad/ Via filled with resin?

4. Is HDI(Buried/blid vias) is a better option?

Thanks a lot!

[Kaja]

Hi, 

I will get back to you within the end of the week. 

Best regards,
Kaja

[Radio]

Sure Thanks!

[Kaja]

Hi, 

see: https://www.pcbgogo.com/blog/What_Is_High_TG_PCB_.html

you should figure out what's the best for your specific design, discussing with the manufacture house. 

Filled and capped vias is recommended to ensure good soldering, see our app note: Circuit Board Guidelines for aQFN Package

Best regards,
Kaja

[Radio]

Hi Kaja,

Thanks for the reply.

I am trying to use the same bluetooth antenna provided in the nRF52840 dongle reference design. When I open the given hardware files, the substrate definitions and the microstrip dimensions are:

Dielectric - 4.8

h - 78.74 mil

trace width - 10 mil

Therefore, I wanted to make sure these same dimensions are preserved, otherwise it is going to affect antenna matching. If there are any further details on the nRF52840 Dongle subrate material please share with me.

Thanks

[Kaja]

I see, 

so regardless of what antenna, and type of PCB the track between the radio matching network and the antenna should be a 50 Ohm transmission line. This means that you have to calculate the width and distance to ground, based on what pcb, substrate you end up using. 

Best regards,
Kaja

[Radio]

Thanks!!