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Four-layer stack-up design in PCB Design - Cell-by-Cell Formula Trace

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Concept Flow

[Identify Layers] → [List Materials] → [Note Thickness] → [Sum Thickness] → [Result: Total PCB Thickness]

This flow shows the steps to understand and calculate the total thickness of a four-layer PCB stack-up by identifying each layer, its material, thickness, and summing all thicknesses.

Formula

Total Thickness = SUM(C2:C5)

This formula adds the thickness values from cells C2 to C5 to calculate the total thickness of the PCB stack-up.

Step-by-Step Trace

Step	Operation	Layers Considered	Thickness Values (mil)	Sum Result (mil)
1	Start sum	None	-	0
2	Add Top Layer thickness	Top Layer	0 + 1.4	1.4
3	Add Prepreg thickness	Top Layer, Prepreg	1.4 + 4.0	5.4
4	Add Inner Layer thickness	Top Layer, Prepreg, Inner Layer	5.4 + 1.4	6.8
5	Add Core thickness	All layers	6.8 + 62.0	68.8

Final total thickness of the four-layer PCB stack-up is 68.8 mil.

Variable Tracker

Step	Variable	Value Before	Operation	Value After
1	Total Thickness	0	Initialize sum	0
2	Total Thickness	0	Add 1.4 (Top Layer)	1.4
3	Total Thickness	1.4	Add 4.0 (Prepreg)	5.4
4	Total Thickness	5.4	Add 1.4 (Inner Layer)	6.8
5	Total Thickness	6.8	Add 62.0 (Core)	68.8

Key Moments

Why do we add the thickness values of all layers?

What role does the Core layer play in the stack-up?

Why is the Prepreg layer important despite being thinner than the Core?

Sheet Trace Quiz - 3 Questions

Test your understanding

What is the total thickness of the four-layer PCB stack-up?

A66.8 mil

B4.0 mil

C68.8 mil

D1.4 mil

Key Result

A four-layer PCB stack-up consists of Top Layer (signal), Prepreg (insulation), Inner Layer (ground plane), and Core (mechanical support). Total thickness is the sum of all layers' thicknesses.

Transcript

We start by identifying each layer in the PCB stack-up and noting its material and thickness. Then, we sum the thickness values from the Top Layer, Prepreg, Inner Layer, and Core to find the total PCB thickness. This total thickness is important for mechanical and electrical design considerations in PCB manufacturing.