LGA-72 Fanout in Kicad

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1

I am using an IC in my board whose package is 6 mm × 5 mm, 72-lead LGA package.I have not done complex boards in Kicad.I believe this one is complex for a beginner like me.

The board contains 3 of these IC’s ,a microcontroller(Most probably STM32), and a BT module.The board size is not a constraint for me.

I did some literature study and come up with a fanout paln for this package.It is given below.May I know your thoughts.

Also any fanout tool exists for Kicad.

Category Specification
IC Package 72-pin LGA, 0.5 mm pitch
Trace Width 6 mil (0.152 mm)
Trace Spacing 6 mil (0.152 mm)
Via Type Standard via
Via Drill Size 0.2 mm
Via Pad Size 0.4 mm
Fanout Strategy Dogbone for outer pads, via-in-pad optional
Stackup (6-layer)
- Layer 1 Top Layer (Signal)
- Layer 2 Ground Plane
- Layer 3 Inner Signal 1
- Layer 4 Inner Signal 2
- Layer 5 Power Plane
- Layer 6 Bottom Layer (Signal)

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2

Not sure I understand the question in relation to KiCad, what is your KiCad specifically related question ?

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The main Kicad related question is I need to know any Kicad tools exits for fanouting

2nd I would like to know the opinion of experienced people ,whether my strategy,I given in the table is fine or not.I mean do I need to make any changes or not

4

OK, but just so you realise, this is a KiCad focussed forum and not suited or meant for general electronics or general ECad questions, we try hard to keep the focus just to KiCad . . . whilst trying to be as helpful as possible :wink:

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Okay sorry for my mistake.I will take care of it.

May I know any fanout tools exists for Kicad

6

So there is a great fanout plugin for Kicad.
OneKiwiTech/kicad-fanout-tool

its not visible in the default kicad plugin library so you need to follow the instructions to add it to the plugin manager

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7

Thank you.

But it does not support LGA.

8

from the perspective of the fanout tool: aren’t BGA and LGA the same?

9

Well…
square pad vs round pad so how teh tool finds the optimal point for the via may be in question.
But the tool does appear to work if you select the correct reference

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10

“Fanout routing” is a strange term that’s come into fashion somehow.
“Fanout” is normallyan electronics term that refers to the output drive capabilities of logic circuits.

What you are looking for is also called “breakout routing” or “escape routing”.

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11

In the options I did not see LGA so I did not proceed further.I will try this

12

That looks like a very easy fanout. Doable in 4L for sure, probably even in 2L. Just drop a via from each pad of the inner rings, they’ve left plenty of space in there.

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13

If you don’t mind can you show a pictorial representation.

14

A web search for fanout layout finds hits which aren’t accidental. Semantic meanings of words tend to change, you can complain but you are fighting against windmills if you’re trying to stop the change.

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Or look at Downloads Form | Analog Devices

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“Fanout” was up for grabs since nobody has designed logic circuits it was relevant to for the past several decades.

Altium has literally an entire menu for fanout routing commands, you’re not going to win this one.

17

This whole thread should have been the original post followed by a couple of useful replies from @Naib. Instead, it’s 16 posts of hall-monitoring and off-topic nitpicking. I had an AI generate a flowchart for acceptable behavior since we humans can’t seem to figure this out.

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