AWR6843: AWR6843

Please refe to below

How much of the solder mask sholud be opend? (below blue box)

Hi Kim,

The distance from the RF ball center till package edge is 1.5mm as shown in the below snap. The solder mask can also be seen in violet.

Regards,

Sreedeep

Hi, Sreedeep.

Thanks for your reply.

I wonder why the solder mask sholud be opend between ball and edge of package.

(What are the disadvanctages of not opening the solder mask from the ball to the edge of pacakge? Solder mask of package outside is surely opend)

 And please share the detail layout guideline. How much of the solder mask should be opend? (between ball to edge of package)

(The snap is just for EVK, and some parts between ball to edge is not open solder mask.)

I absolutely check the EVK layout. But I want to know how to design PCB for antenna area, when I use another stack-up.

Thanks,

Hi Kim,

The solder mask is opened at the ball pads to allow for proper soldering between the package balls and the pads. The space is left between the ball till the package boundary to avoid solder improper contacts.

Kindly refer to the below PCB design guidelines document.

https://www.ti.com/lit/an/spracg5/spracg5.pdf 

The solder mask shouldn't be a major concern when designing the antenna.

Regards,

Sreedeep

HI, Sreedeep,

Thanks for your kind reply.

I already review the spracg5 document, but this document describe just 1 case. (for 77Ghz, particular stack-up)

if we use the RO3003 materials, should the signal pattern be 213um and solder mask open area be 102um?

I think the signal pattern should be designed to fit our stack-up, and signal pattern will be designed as 50 ohm impendance.

How about the area of the solder mask opening? I want to normal guideline for AWR6843. (not particular case)

Thanks,

Hi Kim,

Yes. The signal trace width is calculated from the dielectric constant and the height of the material used.

You can follow the solder mask opening recommendations mentioned in the AWR6843 datasheet land pattern as shown below:

The solder mask opening is recommended to be as little as possible within the package boundary. There are no specific guidelines on this.

Regards,

Sreedeep

Hi Sreedeep,

Thanks for your comment.

I understand there is no specific guidelines. But should be open the solder mask in package? (ball to edge of package)

if right, why sholud be open the solder mask in package? is it better to antenna performance?

if solder mask is not opend in package, what will be happend?

Please give the answer!

Thanks,

Hello Sreedeep K S,

Could you please provide answer for below customer questions? They would like to know 1)if we have PCB guideline for AWRL6843 AND 2) if we have any guidance from ball to outside(edge) of package. Your kind help would be appreciated.

Regards,

Victor Park

Hi Victor,

Kindly give me a day to check with the internal team for any PCB guideline for AWR6843.

The solder mask is not laid over the antenna section as it can change the dielectric constant (solder mask can have different non-zero dielectric value) and disrupt the antenna performance. Hence the solder mask is opened on the ball pad and kept only till the package edge to avoid solder paste to overflow. After the package boundary the solder mask is opened on the antenna section. Hence on the RF traces the solder mask should be as little as possible. 

Do share any doubts you have on this explanation.

Regards,

Sreedeep

Hi, Sreedeep.

I have already asked, I'm curious about the solder mask around the pattern inside the package. Please check again. (Yellow boc in the picture below)

And, Please share the any PCB guideline for AWR6843/AWRL6843.

Thanks,

Manwoo Kim

Hi Kim,

PFA the hardware design checklist for AWR6843.

/cfs-file/__key/communityserver-discussions-components-files/1023/2548.HardwareDesignChecklist_5F00_V0p8_5F00_IWR6843.xlsx

I will confirm more about the solder mask pattern in a day or two.

Regards,

Sreedeep 

Hi Kim,

In the above snap, the green structure is the solder mask and you can see that it is opened at the ball pads and the antenna traces. The solder mask is about 0.23mm long from the ball pad edge to the edge of solder mask marked by red arrow. 

Please share back any queries and apologies for the confusion.

Regards,

Sreedeep

Hi, Sreedeep.

Does this apply consistently regardless of stack-up or frequency?

How to determine the length below blue arrow?

Thanks,

Hi Kim,

There is no consistent figure for this mask opening length. Also, this has very minimal impact to RF performance. Only consideration is that there happens no solder paste overflow.

Regards,

Sreedeep

Hi, Sreedeep.

Thanks for your kind reply.

Add, you shared the HW design checklist. Is there a checklist for IWRL/AWRL6843?

Thanks,

Manwoo Kim

Hi Kim,

There is no Low power variant for 6843. A new upgraded low power device AWRL6844 is to be released soon and the checklist design for that device is under progress.

Regards,

Sreedeep